ovs-vswitchd.conf.db(5)       Open vSwitch Manual      ovs-vswitchd.conf.db(5)



NAME
       ovs-vswitchd.conf.db - Open_vSwitch database schema

       A  database  with  this  schema  holds  the  configuration for one Open
       vSwitch daemon.  The top-level configuration  for  the  daemon  is  the
       Open_vSwitch  table,  which  must  have exactly one record.  Records in
       other tables are significant only when they can be reached directly  or
       indirectly from the Open_vSwitch table.  Records that are not reachable
       from the Open_vSwitch table are automatically deleted  from  the  data‐
       base, except for records in a few distinguished ``root set’’ tables.

   Common Columns
       Most  tables contain two special columns, named other_config and exter
       nal_ids.  These columns have the same form and purpose each place  that
       they appear, so we describe them here to save space later.

              other_config: map of string-string pairs
                     Key-value  pairs  for  configuring  rarely used features.
                     Supported keys, along with the forms taken by their  val‐
                     ues, are documented individually for each table.

                     A  few tables do not have other_config columns because no
                     key-value pairs have yet been defined for them.

              external_ids: map of string-string pairs
                     Key-value pairs for use by external frameworks that inte‐
                     grate  with  Open  vSwitch,  rather  than by Open vSwitch
                     itself.  System integrators should either  use  the  Open
                     vSwitch  development mailing list to coordinate on common
                     key-value definitions,  or  choose  key  names  that  are
                     likely  to  be  unique.   In  some cases, where key-value
                     pairs have been defined that are likely to be widely use‐
                     ful, they are documented individually for each table.

TABLE SUMMARY
       The  following list summarizes the purpose of each of the tables in the
       Open_vSwitch database.  Each table is described in  more  detail  on  a
       later page.

       Table     Purpose
       Open_vSwitch
                 Open vSwitch configuration.
       Bridge    Bridge configuration.
       Port      Port configuration.
       Interface One physical network device in a Port.
       Flow_Table
                 OpenFlow table configuration
       QoS       Quality of Service configuration
       Queue     QoS output queue.
       Mirror    Port mirroring.
       Controller
                 OpenFlow controller configuration.
       Manager   OVSDB management connection.
       NetFlow   NetFlow configuration.
       SSL       SSL configuration.
       sFlow     sFlow configuration.
       IPFIX     IPFIX configuration.
       Flow_Sample_Collector_Set
                 Flow_Sample_Collector_Set configuration.
       AutoAttach
                 AutoAttach configuration.

Open_vSwitch TABLE
       Configuration  for  an  Open vSwitch daemon.  There must be exactly one
       record in the Open_vSwitch table.

   Summary:
       Configuration:
         bridges                     set of Bridges
         ssl                         optional SSL
         external_ids : system-id    optional string
         external_ids : xs-system-uuid
                                     optional string
         other_config : stats-update-interval
                                     optional string, containing  an  integer,
                                     at least 5,000
         other_config : flow-restore-wait
                                     optional string, either true or false
         other_config : flow-limit   optional  string,  containing an integer,
                                     at least 0
         other_config : max-idle     optional string, containing  an  integer,
                                     at least 500
         other_config : n-dpdk-rxqs  optional  string,  containing an integer,
                                     at least 1
         other_config : pmd-cpu-mask
                                     optional string
         other_config : n-handler-threads
                                     optional string, containing  an  integer,
                                     at least 1
         other_config : n-revalidator-threads
                                     optional  string,  containing an integer,
                                     at least 1
       Status:
         next_cfg                    integer
         cur_cfg                     integer
         Statistics:
            other_config : enable-statistics
                                     optional string, either true or false
            statistics : cpu         optional string, containing  an  integer,
                                     at least 1
            statistics : load_average
                                     optional string
            statistics : memory      optional string
            statistics : process_NAME
                                     optional string
            statistics : file_systems
                                     optional string
       Version Reporting:
         ovs_version                 optional string
         db_version                  optional string
         system_type                 optional string
         system_version              optional string
       Capabilities:
         datapath_types              set of strings
         iface_types                 set of strings
       Database Configuration:
         manager_options             set of Managers
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Configuration:

       bridges: set of Bridges
              Set of bridges managed by the daemon.

       ssl: optional SSL
              SSL used globally by the daemon.

       external_ids : system-id: optional string
              A  unique  identifier for the Open vSwitch’s physical host.  The
              form of the identifier depends on the type of the  host.   On  a
              Citrix  XenServer,  this  will  likely  be  the  same  as exter
              nal_ids:xs-system-uuid.

       external_ids : xs-system-uuid: optional string
              The Citrix XenServer universally unique identifier for the phys‐
              ical host as displayed by xe host-list.

       other_config  :  stats-update-interval:  optional string, containing an
       integer, at least 5,000
              Interval for updating statistics to the database,  in  millisec‐
              onds.  This option will affect the update of the statistics col‐
              umn in the following tables: Port, Interface , Mirror.

              Default value is 5000 ms.

              Getting statistics more frequently can be achieved via OpenFlow.

       other_config : flow-restore-wait: optional string, either true or false
              When ovs-vswitchd starts up, it has  an  empty  flow  table  and
              therefore it handles all arriving packets in its default fashion
              according to its configuration, by dropping them or sending them
              to  an  OpenFlow  controller  or  switching them as a standalone
              switch.  This behavior is  ordinarily  desirable.   However,  if
              ovs-vswitchd  is  restarting  as part of a ``hot-upgrade,’’ then
              this leads to a relatively long period during which packets  are
              mishandled.

              This  option  allows  for improvement.  When ovs-vswitchd starts
              with this value set as true, it will  neither  flush  or  expire
              previously  set  datapath flows nor will it send and receive any
              packets to or from the datapath.  When this value is  later  set
              to  false,  ovs-vswitchd  will  start receiving packets from the
              datapath and re-setup the flows.

              Thus, with this option,  the  procedure  for  a  hot-upgrade  of
              ovs-vswitchd becomes roughly the following:

              1.
                Stop ovs-vswitchd.

              2.
                Set other_config:flow-restore-wait to true.

              3.
                Start ovs-vswitchd.

              4.
                Use ovs-ofctl (or some other program, such as an OpenFlow con‐
                troller) to restore the OpenFlow flow  table  to  the  desired
                state.

              5.
                Set  other_config:flow-restore-wait  to  false  (or  remove it
                entirely from the database).

              The ovs-ctl’s ``restart’’  and  ``force-reload-kmod’’  functions
              use the above config option during hot upgrades.

       other_config  :  flow-limit: optional string, containing an integer, at
       least 0
              The maximum number of flows allowed in the datapath flow  table.
              Internally  OVS  will  choose  a flow limit which will likely be
              lower than this number, based on real time  network  conditions.
              Tweaking  this value is discouraged unless you know exactly what
              you’re doing.

              The default is 200000.

       other_config : max-idle: optional string,  containing  an  integer,  at
       least 500
              The  maximum  time (in ms) that idle flows will remain cached in
              the datapath. Internally OVS will check the validity and  activ‐
              ity  for  datapath  flows regularly and may expire flows quicker
              than this number, based on real time network conditions.  Tweak‐
              ing  this  value  is  discouraged  unless  you know exactly what
              you’re doing.

              The default is 10000.

       other_config : n-dpdk-rxqs: optional string, containing an integer,  at
       least 1
              Specifies the maximum number of rx queues to be created for each
              dpdk interface.  If not specified or  specified  to  0,  one  rx
              queue will be created for each dpdk interface by default.

       other_config : pmd-cpu-mask: optional string
              Specifies  CPU  mask  for  setting the cpu affinity of PMD (Poll
              Mode Driver) threads.  Value  should  be  in  the  form  of  hex
              string,  similar  to  the dpdk EAL ’-c COREMASK’ option input or
              the ’taskset’ mask input.

              The lowest order bit corresponds to the first CPU core.   A  set
              bit  means  the corresponding core is available and a pmd thread
              will be created and pinned to it.  If the input does  not  cover
              all cores, those uncovered cores are considered not set.

              If  not  specified, one pmd thread will be created for each numa
              node and pinned to any  available  core  on  the  numa  node  by
              default.

       other_config  : n-handler-threads: optional string, containing an inte‐
       ger, at least 1
              Specifies the number of threads for software  datapaths  to  use
              for  handling  new  flows.  The default the number of online CPU
              cores minus the number of revalidators.

              This configuration is per datapath.  If you have more  than  one
              software  datapath  (e.g.  some  system  bridges and some netdev
              bridges), then the total number of threads is  n-handler-threads
              times the number of software datapaths.

       other_config  :  n-revalidator-threads:  optional string, containing an
       integer, at least 1
              Specifies the number of threads for software  datapaths  to  use
              for  revalidating  flows in the datapath.  Typically, there is a
              direct correlation between the number  of  revalidator  threads,
              and the number of flows allowed in the datapath.  The default is
              the number of cpu cores divided by four  plus  one.   If  n-han
              dler-threads  is  set,  the default changes to the number of cpu
              cores minus the number of handler threads.

              This configuration is per datapath.  If you have more  than  one
              software  datapath  (e.g.  some  system  bridges and some netdev
              bridges), then the total number of threads is  n-handler-threads
              times the number of software datapaths.

     Status:

       next_cfg: integer
              Sequence number for client to increment.  When a client modifies
              any part of the database configuration and wishes  to  wait  for
              Open  vSwitch  to  finish applying the changes, it may increment
              this sequence number.

       cur_cfg: integer
              Sequence number that Open vSwitch sets to the current  value  of
              next_cfg  after  it  finishes  applying  a  set of configuration
              changes.

     Statistics:
       The statistics column contains key-value pairs that  report  statistics
       about a system running an Open vSwitch.  These are updated periodically
       (currently, every 5 seconds).  Key-value pairs that  cannot  be  deter‐
       mined or that do not apply to a platform are omitted.

       other_config : enable-statistics: optional string, either true or false
              Statistics are disabled by default to avoid overhead in the com‐
              mon case when statistics gathering  is  not  useful.   Set  this
              value  to  true to enable populating the statistics column or to
              false to explicitly disable it.

       statistics : cpu: optional string, containing an integer, at least 1
              Number of CPU processors, threads, or cores currently online and
              available  to the operating system on which Open vSwitch is run‐
              ning,  as  an  integer.   This  may  be  less  than  the  number
              installed,  if  some are not online or if they are not available
              to the operating system.

              Open vSwitch userspace processes are not multithreaded, but  the
              Linux kernel-based datapath is.

       statistics : load_average: optional string
              A  comma-separated  list of three floating-point numbers, repre‐
              senting the system load average over the last 1, 5, and 15  min‐
              utes, respectively.

       statistics : memory: optional string
              A  comma-separated  list of integers, each of which represents a
              quantity of memory in kilobytes  that  describes  the  operating
              system  on  which Open vSwitch is running.  In respective order,
              these values are:

              1.
                Total amount of RAM allocated to the OS.

              2.
                RAM allocated to the OS that is in use.

              3.
                RAM that can be flushed out to disk or otherwise discarded  if
                that space is needed for another purpose.  This number is nec‐
                essarily less than or equal to the previous value.

              4.
                Total disk space allocated for swap.

              5.
                Swap space currently in use.

              On Linux, all five values can be determined  and  are  included.
              On  other  operating  systems,  only the first two values can be
              determined, so the list will only have two values.

       statistics : process_NAME: optional string
              One such key-value pair, with NAME replaced by a  process  name,
              will  exist  for  each running Open vSwitch daemon process, with
              name replaced by the daemon’s name (e.g.  process_ovs-vswitchd).
              The  value  is a comma-separated list of integers.  The integers
              represent the following, with memory measured in  kilobytes  and
              durations in milliseconds:

              1.
                The process’s virtual memory size.

              2.
                The process’s resident set size.

              3.
                The  amount  of  user  and  system  CPU  time  consumed by the
                process.

              4.
                The number of times that the  process  has  crashed  and  been
                automatically restarted by the monitor.

              5.
                The duration since the process was started.

              6.
                The duration for which the process has been running.

              The  interpretation  of  some of these values depends on whether
              the process was started with the --monitor.  If it was not, then
              the  crash  count  will  always  be 0 and the two durations will
              always be the same.  If --monitor  was  given,  then  the  crash
              count  may  be  positive;  if  it is, the latter duration is the
              amount of time since the most recent crash and restart.

              There will be one key-value pair for each file in Open vSwitch’s
              ``run directory’’ (usually /var/run/openvswitch) whose name ends
              in .pid, whose contents are a process ID, and which is locked by
              a running process.  The name is taken from the pidfile’s name.

              Currently  Open  vSwitch is only able to obtain all of the above
              detail on Linux systems.  On other systems, the  same  key-value
              pairs  will  be  present but the values will always be the empty
              string.

       statistics : file_systems: optional string
              A space-separated list of information on  local,  writable  file
              systems.   Each  item  in the list describes one file system and
              consists in turn of a comma-separated list of the following:

              1.
                Mount point, e.g. / or /var/log.  Any spaces or commas in  the
                mount point are replaced by underscores.

              2.
                Total size, in kilobytes, as an integer.

              3.
                Amount of storage in use, in kilobytes, as an integer.

              This  key-value  pair is omitted if there are no local, writable
              file systems or if Open vSwitch cannot obtain the needed  infor‐
              mation.

     Version Reporting:
       These  columns  report the types and versions of the hardware and soft‐
       ware running Open vSwitch.   We  recommend  in  general  that  software
       should  test whether specific features are supported instead of relying
       on version number checks.  These  values  are  primarily  intended  for
       reporting to human administrators.

       ovs_version: optional string
              The Open vSwitch version number, e.g. 1.1.0.

       db_version: optional string
              The    database    schema    version    number   in   the   form
              major.minor.tweak, e.g. 1.2.3.  Whenever the database schema  is
              changed in a non-backward compatible way (e.g. deleting a column
              or a table), major is incremented.  When the database schema  is
              changed in a backward compatible way (e.g. adding a new column),
              minor is incremented.  When the database schema is changed  cos‐
              metically (e.g. reindenting its syntax), tweak is incremented.

              The  schema  version  is  part of the database schema, so it can
              also be retrieved by fetching the schema using the Open  vSwitch
              database protocol.

       system_type: optional string
              An  identifier  for  the  type  of  system  on top of which Open
              vSwitch runs, e.g. XenServer or KVM.

              System integrators are responsible for choosing and  setting  an
              appropriate value for this column.

       system_version: optional string
              The  version  of  the  system  identified  by  system_type, e.g.
              5.6.100-39265p on XenServer 5.6.100 build 39265.

              System integrators are responsible for choosing and  setting  an
              appropriate value for this column.

     Capabilities:
       These columns report capabilities of the Open vSwitch instance.

       datapath_types: set of strings
              This column reports the different dpifs registered with the sys‐
              tem.  These are the values that this instance  supports  in  the
              datapath_type column of the Bridge table.

       iface_types: set of strings
              This  column  reports  the different netdevs registered with the
              system.  These are the values that this instance supports in the
              type column of the Interface table.

     Database Configuration:
       These   columns   primarily   configure   the   Open  vSwitch  database
       (ovsdb-server), not the Open vSwitch switch (ovs-vswitchd).  The  OVSDB
       database also uses the ssl settings.

       The  Open vSwitch switch does read the database configuration to deter‐
       mine remote IP addresses to which in-band control should apply.

       manager_options: set of Managers
              Database clients to  which  the  Open  vSwitch  database  server
              should  connect or to which it should listen, along with options
              for how these connection should be configured.  See the  Manager
              table for more information.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Bridge TABLE
       Configuration for a bridge within an Open_vSwitch.

       A Bridge  record  represents  an  Ethernet  switch  with  one  or  more
       ``ports,’’  which are the Port records pointed to by the Bridge’s ports
       column.

   Summary:
       Core Features:
         name                        immutable string (must be  unique  within
                                     table)
         ports                       set of Ports
         mirrors                     set of Mirrors
         netflow                     optional NetFlow
         sflow                       optional sFlow
         ipfix                       optional IPFIX
         flood_vlans                 set  of  up to 4,096 integers, in range 0
                                     to 4,095
         auto_attach                 optional AutoAttach
       OpenFlow Configuration:
         controller                  set of Controllers
         flow_tables                 map of integer-Flow_Table pairs,  key  in
                                     range 0 to 254
         fail_mode                   optional  string, either secure or stand
                                     alone
         datapath_id                 optional string
         datapath_version            string
         other_config : datapath-id  optional string
         other_config : dp-desc      optional string
         other_config : disable-in-band
                                     optional string, either true or false
         other_config : in-band-queue
                                     optional string, containing  an  integer,
                                     in range 0 to 4,294,967,295
         protocols                   set  of strings, one of OpenFlow11, Open
                                     Flow10,  OpenFlow13,  OpenFlow12,   Open
                                     Flow15, or OpenFlow14
       Spanning Tree Configuration:
         STP Configuration:
            stp_enable               boolean
            other_config : stp-system-id
                                     optional string
            other_config : stp-priority
                                     optional  string,  containing an integer,
                                     in range 0 to 65,535
            other_config : stp-hello-time
                                     optional string, containing  an  integer,
                                     in range 1 to 10
            other_config : stp-max-age
                                     optional  string,  containing an integer,
                                     in range 6 to 40
            other_config : stp-forward-delay
                                     optional string, containing  an  integer,
                                     in range 4 to 30
            other_config : mcast-snooping-aging-time
                                     optional  string,  containing an integer,
                                     at least 1
            other_config : mcast-snooping-table-size
                                     optional string, containing  an  integer,
                                     at least 1
            other_config : mcast-snooping-disable-flood-unregistered
                                     optional string, either true or false
         STP Status:
            status : stp_bridge_id   optional string
            status : stp_designated_root
                                     optional string
            status : stp_root_path_cost
                                     optional string
       Rapid Spanning Tree:
         RSTP Configuration:
            rstp_enable              boolean
            other_config : rstp-address
                                     optional string
            other_config : rstp-priority
                                     optional  string,  containing an integer,
                                     in range 0 to 61,440
            other_config : rstp-ageing-time
                                     optional string, containing  an  integer,
                                     in range 10 to 1,000,000
            other_config : rstp-force-protocol-version
                                     optional string, containing an integer
            other_config : rstp-max-age
                                     optional  string,  containing an integer,
                                     in range 6 to 40
            other_config : rstp-forward-delay
                                     optional string, containing  an  integer,
                                     in range 4 to 30
            other_config : rstp-transmit-hold-count
                                     optional  string,  containing an integer,
                                     in range 1 to 10
         RSTP Status:
            rstp_status : rstp_bridge_id
                                     optional string
            rstp_status : rstp_root_id
                                     optional string
            rstp_status : rstp_root_path_cost
                                     optional string, containing  an  integer,
                                     at least 0
            rstp_status : rstp_designated_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_bridge_port_id
                                     optional string
       Multicast Snooping Configuration:
         mcast_snooping_enable       boolean
       Other Features:
         datapath_type               string
         external_ids : bridge-id    optional string
         external_ids : xs-network-uuids
                                     optional string
         other_config : hwaddr       optional string
         other_config : forward-bpdu
                                     optional string, either true or false
         other_config : mac-aging-time
                                     optional  string,  containing an integer,
                                     at least 1
         other_config : mac-table-size
                                     optional string, containing  an  integer,
                                     at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Bridge  identifier.   Should  be  alphanumeric  and no more than
              about 8 bytes long.  Must be unique among the  names  of  ports,
              interfaces, and bridges on a host.

       ports: set of Ports
              Ports included in the bridge.

       mirrors: set of Mirrors
              Port mirroring configuration.

       netflow: optional NetFlow
              NetFlow configuration.

       sflow: optional sFlow
              sFlow(R) configuration.

       ipfix: optional IPFIX
              IPFIX configuration.

       flood_vlans: set of up to 4,096 integers, in range 0 to 4,095
              VLAN  IDs  of VLANs on which MAC address learning should be dis‐
              abled, so that packets are flooded instead of being sent to spe‐
              cific  ports  that  are believed to contain packets’ destination
              MACs.  This should ordinarily be used to disable MAC learning on
              VLANs  used  for mirroring (RSPAN VLANs).  It may also be useful
              for debugging.

              SLB bonding (see the bond_mode column  in  the  Port  table)  is
              incompatible  with  flood_vlans.  Consider using another bonding
              mode or a different type of mirror instead.

       auto_attach: optional AutoAttach
              Auto Attach configuration.

     OpenFlow Configuration:

       controller: set of Controllers
              OpenFlow controller set.  If unset, then no OpenFlow controllers
              will be used.

              If  there  are  primary controllers, removing all of them clears
              the flow table.  If there are no primary controllers, adding one
              also  clears  the  flow table.  Other changes to the set of con‐
              trollers, such as  adding  or  removing  a  service  controller,
              adding another primary controller to supplement an existing pri‐
              mary controller, or  removing  only  one  of  two  primary  con‐
              trollers, have no effect on the flow table.

       flow_tables: map of integer-Flow_Table pairs, key in range 0 to 254
              Configuration for OpenFlow tables.  Each pair maps from an Open‐
              Flow table ID to configuration for that table.

       fail_mode: optional string, either secure or standalone
              When a controller is configured, it is, ordinarily,  responsible
              for setting up all flows on the switch.  Thus, if the connection
              to the controller fails, no new network connections can  be  set
              up.  If the connection to the controller stays down long enough,
              no packets can pass through the switch  at  all.   This  setting
              determines the switch’s response to such a situation.  It may be
              set to one of the following:

              standalone
                     If no message is received from the controller  for  three
                     times   the   inactivity  probe  interval  (see  inactiv
                     ity_probe), then Open vSwitch will take over responsibil‐
                     ity  for  setting  up  flows.  In this mode, Open vSwitch
                     causes the bridge to act like  an  ordinary  MAC-learning
                     switch.   Open  vSwitch will continue to retry connecting
                     to the controller in the background and, when the connec‐
                     tion  succeeds, it will discontinue its standalone behav‐
                     ior.

              secure Open vSwitch will not set up flows on its  own  when  the
                     controller  connection  fails  or when no controllers are
                     defined.  The bridge will continue to retry connecting to
                     any defined controllers forever.

              The default is standalone if the value is unset, but future ver‐
              sions of Open vSwitch may change the default.

              The standalone mode can create forwarding loops on a bridge that
              has  more  than one uplink port unless STP is enabled.  To avoid
              loops on such a bridge, configure secure mode or enable STP (see
              stp_enable).

              When  more  than one controller is configured, fail_mode is con‐
              sidered only when none of the configured controllers can be con‐
              tacted.

              Changing  fail_mode  when  no primary controllers are configured
              clears the flow table.

       datapath_id: optional string
              Reports the OpenFlow datapath ID in use.  Exactly 16 hex digits.
              (Setting  this  column  has  no  useful  effect.  Set other-con
              fig:datapath-id instead.)

       datapath_version: string
              Reports the version number of the Open vSwitch datapath in  use.
              This  allows management software to detect and report discrepan‐
              cies between Open vSwitch userspace and datapath versions.  (The
              ovs_version  column in the Open_vSwitch reports the Open vSwitch
              userspace version.)  The version reported depends on  the  data‐
              path in use:

              ·      When  the  kernel  module  included  in  the Open vSwitch
                     source tree is used, this column reports the Open vSwitch
                     version from which the module was taken.

              ·      When the kernel module that is part of the upstream Linux
                     kernel is used, this column reports unknown>gt;>gt;.

              ·      When the datapath is built into the ovs-vswitchd  binary,
                     this  column  reports built-in>gt;>gt;.  A built-in datapath is
                     by definition the same version as the rest  of  the  Open
                     VSwitch userspace.

              ·      Other  datapaths  (such  as  the Hyper-V kernel datapath)
                     currently report unknown>gt;>gt;.

              A version discrepancy between ovs-vswitchd and the  datapath  in
              use  is  not  normally cause for alarm.  The Open vSwitch kernel
              datapaths for Linux and Hyper-V, in particular, are designed for
              maximum inter-version compatibility: any userspace version works
              with with any kernel version.  Some reasons do exist  to  insist
              on  particular  user/kernel  pairings.  First, newer kernel ver‐
              sions add new features, that can  only  be  used  by  new-enough
              userspace,   e.g.   VXLAN  tunneling  requires  certain  minimal
              userspace and kernel versions.  Second, as an extension  to  the
              first  reason,  some  newer kernel versions add new features for
              enhancing performance that only  new-enough  userspace  versions
              can take advantage of.

       other_config : datapath-id: optional string
              Exactly  16 hex digits to set the OpenFlow datapath ID to a spe‐
              cific value.  May not be all-zero.

       other_config : dp-desc: optional string
              Human readable description of datapath.  It  it  a  maximum  256
              byte-long  free-form  string to describe the datapath for debug‐
              ging purposes, e.g. switch3 in room 3120.

       other_config : disable-in-band: optional string, either true or false
              If set to true, disable in-band control on the bridge regardless
              of controller and manager settings.

       other_config  :  in-band-queue: optional string, containing an integer,
       in range 0 to 4,294,967,295
              A queue ID as a nonnegative integer.   This  sets  the  OpenFlow
              queue ID that will be used by flows set up by in-band control on
              this bridge.  If unset, or if the port used by an  in-band  con‐
              trol  flow does not have QoS configured, or if the port does not
              have a queue with the specified ID, the default  queue  is  used
              instead.

       protocols:  set  of strings, one of OpenFlow11, OpenFlow10, OpenFlow13,
       OpenFlow12, OpenFlow15, or OpenFlow14
              List of OpenFlow protocols that may be used when  negotiating  a
              connection  with  a controller.  OpenFlow 1.0, 1.1, 1.2, and 1.3
              are enabled by default if this column is empty.

              OpenFlow 1.4 is not enabled by default because  its  implementa‐
              tion is missing features.

              OpenFlow  1.5 has the same risks as OpenFlow 1.4, but it is even
              more experimental because  the  OpenFlow  1.5  specification  is
              still  under  development  and  thus  subject  to  change.  Pass
              --enable-of15 to  ovs-vswitchd  to  allow  OpenFlow  1.5  to  be
              enabled.

     Spanning Tree Configuration:
       The IEEE 802.1D Spanning Tree Protocol (STP) is a network protocol that
       ensures loop-free topologies.  It allows redundant links to be included
       in  the  network  to provide automatic backup paths if the active links
       fails.

       These settings configure the slower-to-converge but still  widely  sup‐
       ported   version   of   Spanning  Tree  Protocol,  sometimes  known  as
       802.1D-1998.  Open vSwitch also supports the newer Rapid Spanning  Tree
       Protocol  (RSTP), documented later in the section titled Rapid Spanning
       Tree Configuration.

     STP Configuration:

       stp_enable: boolean
              Enable spanning tree on the bridge.  By default, STP is disabled
              on  bridges.  Bond, internal, and mirror ports are not supported
              and will not participate in the spanning tree.

              STP and RSTP are mutually exclusive.  If both are enabled,  RSTP
              will be used.

       other_config : stp-system-id: optional string
              The bridge’s STP identifier (the lower 48 bits of the bridge-id)
              in the form xx:xx:xx:xx:xx:xx.  By default,  the  identifier  is
              the MAC address of the bridge.

       other_config : stp-priority: optional string, containing an integer, in
       range 0 to 65,535
              The bridge’s relative priority value for  determining  the  root
              bridge  (the upper 16 bits of the bridge-id).  A bridge with the
              lowest bridge-id is elected the root.  By default, the  priority
              is 0x8000.

       other_config  : stp-hello-time: optional string, containing an integer,
       in range 1 to 10
              The interval between transmissions of hello messages  by  desig‐
              nated  ports,  in  seconds.   By default the hello interval is 2
              seconds.

       other_config : stp-max-age: optional string, containing an integer,  in
       range 6 to 40
              The  maximum  age  of  the information transmitted by the bridge
              when it is the root bridge, in seconds.  By default, the maximum
              age is 20 seconds.

       other_config  : stp-forward-delay: optional string, containing an inte‐
       ger, in range 4 to 30
              The delay to wait  between  transitioning  root  and  designated
              ports  to  forwarding,  in  seconds.  By default, the forwarding
              delay is 15 seconds.

       other_config : mcast-snooping-aging-time: optional  string,  containing
       an integer, at least 1
              The  maximum  number  of  seconds to retain a multicast snooping
              entry for which no packets have been seen.  The default is  cur‐
              rently  300  seconds  (5  minutes).  The value, if specified, is
              forced into a reasonable range, currently 15 to 3600 seconds.

       other_config : mcast-snooping-table-size: optional  string,  containing
       an integer, at least 1
              The  maximum  number  of  multicast snooping addresses to learn.
              The default is currently 2048.   The  value,  if  specified,  is
              forced into a reasonable range, currently 10 to 1,000,000.

       other_config   :   mcast-snooping-disable-flood-unregistered:  optional
       string, either true or false
              If set to false, unregistered multicast packets are forwarded to
              all  ports.   If set to true, unregistered multicast packets are
              forwarded to ports connected to multicast routers.

     STP Status:
       These key-value pairs report  the  status  of  802.1D-1998.   They  are
       present only if STP is enabled (via the stp_enable column).

       status : stp_bridge_id: optional string
              The  bridge ID used in spanning tree advertisements, in the form
              xxxx.yyyyyyyyyyyy where the xs are the STP priority, the ys  are
              the STP system ID, and each x and y is a hex digit.

       status : stp_designated_root: optional string
              The  designated root for this spanning tree, in the same form as
              status:stp_bridge_id.  If this bridge is  the  root,  this  will
              have  the  same value as status:stp_bridge_id, otherwise it will
              differ.

       status : stp_root_path_cost: optional string
              The path cost of reaching the designated bridge.  A lower number
              is better.  The value is 0 if this bridge is the root, otherwise
              it is higher.

     Rapid Spanning Tree:
       Rapid Spanning Tree Protocol (RSTP), like STP, is  a  network  protocol
       that ensures loop-free topologies.  RSTP superseded STP with the publi‐
       cation of 802.1D-2004.  Compared to STP, RSTP  converges  more  quickly
       and recovers more quickly from failures.

     RSTP Configuration:

       rstp_enable: boolean
              Enable  Rapid  Spanning Tree on the bridge.  By default, RSTP is
              disabled on bridges.  Bond, internal, and mirror ports  are  not
              supported and will not participate in the spanning tree.

              STP  and RSTP are mutually exclusive.  If both are enabled, RSTP
              will be used.

       other_config : rstp-address: optional string
              The bridge’s RSTP address (the lower 48 bits of  the  bridge-id)
              in  the  form xx:xx:xx:xx:xx:xx.  By default, the address is the
              MAC address of the bridge.

       other_config : rstp-priority: optional string, containing  an  integer,
       in range 0 to 61,440
              The  bridge’s  relative  priority value for determining the root
              bridge (the upper 16 bits of the bridge-id).  A bridge with  the
              lowest  bridge-id is elected the root.  By default, the priority
              is 0x8000 (32768).  This value needs to be a multiple  of  4096,
              otherwise it’s rounded to the nearest inferior one.

       other_config  :  rstp-ageing-time: optional string, containing an inte‐
       ger, in range 10 to 1,000,000
              The Ageing Time parameter for the Bridge.  The default value  is
              300 seconds.

       other_config : rstp-force-protocol-version: optional string, containing
       an integer
              The Force Protocol Version parameter for the Bridge.   This  can
              take  the  value  0  (STP Compatibility mode) or 2 (the default,
              normal operation).

       other_config : rstp-max-age: optional string, containing an integer, in
       range 6 to 40
              The  maximum  age  of  the information transmitted by the Bridge
              when it is the Root Bridge.  The default value is 20.

       other_config : rstp-forward-delay: optional string, containing an inte‐
       ger, in range 4 to 30
              The  delay used by STP Bridges to transition Root and Designated
              Ports to Forwarding.  The default value is 15.

       other_config : rstp-transmit-hold-count: optional string, containing an
       integer, in range 1 to 10
              The  Transmit Hold Count used by the Port Transmit state machine
              to limit transmission rate.  The default value is 6.

     RSTP Status:
       These key-value pairs report  the  status  of  802.1D-2004.   They  are
       present only if RSTP is enabled (via the rstp_enable column).

       rstp_status : rstp_bridge_id: optional string
              The bridge ID used in rapid spanning tree advertisements, in the
              form x.yyy.zzzzzzzzzzzz where x is the RSTP priority, the ys are
              a  locally assigned system ID extension, the zs are the STP sys‐
              tem ID, and each x, y, or z is a hex digit.

       rstp_status : rstp_root_id: optional string
              The root of this spanning tree, in the same  form  as  rstp_sta
              tus:rstp_bridge_id.   If this bridge is the root, this will have
              the same value as rstp_status:rstp_bridge_id, otherwise it  will
              differ.

       rstp_status : rstp_root_path_cost: optional string, containing an inte‐
       ger, at least 0
              The path cost of reaching the root.  A lower number  is  better.
              The  value  is  0  if  this  bridge is the root, otherwise it is
              higher.

       rstp_status : rstp_designated_id: optional string
              The  RSTP  designated  ID,  in  the  same  form   as   rstp_sta
              tus:rstp_bridge_id.

       rstp_status : rstp_designated_port_id: optional string
              The RSTP designated port ID, as a 4-digit hex number.

       rstp_status : rstp_bridge_port_id: optional string
              The RSTP bridge port ID, as a 4-digit hex number.

     Multicast Snooping Configuration:
       Multicast  snooping  (RFC  4541) monitors the Internet Group Management
       Protocol (IGMP) and Multicast Listener Discovery traffic between  hosts
       and  multicast  routers.   The  switch  uses what IGMP and MLD snooping
       learns to forward multicast traffic only to interfaces  that  are  con‐
       nected  to interested receivers.  Currently it supports IGMPv1, IGMPv2,
       IGMPv3, MLDv1 and MLDv2 protocols.

       mcast_snooping_enable: boolean
              Enable multicast snooping on the bridge. For now, the default is
              disabled.

     Other Features:

       datapath_type: string
              Name of datapath provider.  The kernel datapath has type system.
              The userspace datapath has type netdev.  A manager may refer  to
              the  datapath_types  column of the Open_vSwitch table for a list
              of the types accepted by this Open vSwitch instance.

       external_ids : bridge-id: optional string
              A unique identifier of the bridge.   On  Citrix  XenServer  this
              will commonly be the same as external_ids:xs-network-uuids.

       external_ids : xs-network-uuids: optional string
              Semicolon-delimited  set of universally unique identifier(s) for
              the network with which this bridge is  associated  on  a  Citrix
              XenServer  host.   The network identifiers are RFC 4122 UUIDs as
              displayed by, e.g., xe network-list.

       other_config : hwaddr: optional string
              An Ethernet address in the form  xx:xx:xx:xx:xx:xx  to  set  the
              hardware  address  of  the local port and influence the datapath
              ID.

       other_config : forward-bpdu: optional string, either true or false
              Controls forwarding of BPDUs and other  network  control  frames
              when  NORMAL  action  is  invoked.  When this option is false or
              unset, frames with reserved Ethernet addresses (see table below)
              will  not  be  forwarded.  When this option is true, such frames
              will not be treated specially.

              The above general rule has the following exceptions:

              ·      If STP is enabled on the bridge (see the stp_enable  col‐
                     umn  in  the  Bridge  table),  the  bridge  processes all
                     received STP packets and never passes them to OpenFlow or
                     forwards  them.   This is true even if STP is disabled on
                     an individual port.

              ·      If LLDP is enabled on an interface (see the  lldp  column
                     in the Interface table), the interface processes received
                     LLDP packets and never passes them to  OpenFlow  or  for‐
                     wards them.

              Set this option to true if the Open vSwitch bridge connects dif‐
              ferent Ethernet networks and is not configured to participate in
              STP.

              This  option  affects packets with the following destination MAC
              addresses:

              01:80:c2:00:00:00
                     IEEE 802.1D Spanning Tree Protocol (STP).

              01:80:c2:00:00:01
                     IEEE Pause frame.

              01:80:c2:00:00:0x
                     Other reserved protocols.

              00:e0:2b:00:00:00
                     Extreme Discovery Protocol (EDP).

              00:e0:2b:00:00:04 and 00:e0:2b:00:00:06
                     Ethernet Automatic Protection Switching (EAPS).

              01:00:0c:cc:cc:cc
                     Cisco Discovery Protocol (CDP),  VLAN  Trunking  Protocol
                     (VTP),  Dynamic Trunking Protocol (DTP), Port Aggregation
                     Protocol (PAgP), and others.

              01:00:0c:cc:cc:cd
                     Cisco Shared Spanning Tree Protocol PVSTP+.

              01:00:0c:cd:cd:cd
                     Cisco STP Uplink Fast.

              01:00:0c:00:00:00
                     Cisco Inter Switch Link.

              01:00:0c:cc:cc:cx
                     Cisco CFM.

       other_config : mac-aging-time: optional string, containing an  integer,
       at least 1
              The maximum number of seconds to retain a MAC learning entry for
              which no packets have been seen.  The default is  currently  300
              seconds  (5 minutes).  The value, if specified, is forced into a
              reasonable range, currently 15 to 3600 seconds.

              A short MAC aging time allows a network to more  quickly  detect
              that  a  host is no longer connected to a switch port.  However,
              it also makes it more likely that packets will be flooded unnec‐
              essarily,  when  they  are  addressed  to  a connected host that
              rarely transmits packets.  To reduce the incidence  of  unneces‐
              sary  flooding,  use  a  MAC  aging time longer than the maximum
              interval at which a host will ordinarily transmit packets.

       other_config : mac-table-size: optional string, containing an  integer,
       at least 1
              The  maximum  number  of MAC addresses to learn.  The default is
              currently 2048.  The value, if specified, is forced into a  rea‐
              sonable range, currently 10 to 1,000,000.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Port TABLE
       A port within a Bridge.

       Most commonly, a port has exactly one ``interface,’’ pointed to by  its
       interfaces  column.   Such  a port logically corresponds to a port on a
       physical Ethernet switch.  A port with more than  one  interface  is  a
       ``bonded port’’ (see Bonding Configuration).

       Some  properties  that one might think as belonging to a port are actu‐
       ally part of the port’s Interface members.

   Summary:
       name                          immutable string (must be  unique  within
                                     table)
       interfaces                    set of 1 or more Interfaces
       VLAN Configuration:
         vlan_mode                   optional    string,    one   of   access,
                                     native-tagged, native-untagged, or trunk
         tag                         optional integer, in range 0 to 4,095
         trunks                      set of up to 4,096 integers, in  range  0
                                     to 4,095
         other_config : priority-tags
                                     optional string, either true or false
       Bonding Configuration:
         bond_mode                   optional  string,  one  of active-backup,
                                     balance-tcp, or balance-slb
         other_config : bond-hash-basis
                                     optional string, containing an integer
         Link Failure Detection:
            other_config : bond-detect-mode
                                     optional string, either miimon or carrier
            other_config : bond-miimon-interval
                                     optional string, containing an integer
            bond_updelay             integer
            bond_downdelay           integer
         LACP Configuration:
            lacp                     optional string, one of active,  passive,
                                     or off
            other_config : lacp-system-id
                                     optional string
            other_config : lacp-system-priority
                                     optional  string,  containing an integer,
                                     in range 1 to 65,535
            other_config : lacp-time optional string, either slow or fast
            other_config : lacp-fallback-ab
                                     optional string, either true or false
         Rebalancing Configuration:
            other_config : bond-rebalance-interval
                                     optional string, containing  an  integer,
                                     in range 0 to 10,000
         bond_fake_iface             boolean
       Spanning Tree Protocol:
         STP Configuration:
            other_config : stp-enable
                                     optional string, either true or false
            other_config : stp-port-num
                                     optional  string,  containing an integer,
                                     in range 1 to 255
            other_config : stp-port-priority
                                     optional string, containing  an  integer,
                                     in range 0 to 255
            other_config : stp-path-cost
                                     optional  string,  containing an integer,
                                     in range 0 to 65,535
         STP Status:
            status : stp_port_id     optional string
            status : stp_state       optional string, one  of  disabled,  for
                                     warding, learning, listening, or blocking
            status : stp_sec_in_state
                                     optional  string,  containing an integer,
                                     at least 0
            status : stp_role        optional  string,  one   of   designated,
                                     alternate, or root
       Rapid Spanning Tree Protocol:
         RSTP Configuration:
            other_config : rstp-enable
                                     optional string, either true or false
            other_config : rstp-port-priority
                                     optional  string,  containing an integer,
                                     in range 0 to 240
            other_config : rstp-port-num
                                     optional string, containing  an  integer,
                                     in range 1 to 4,095
            other_config : rstp-port-path-cost
                                     optional string, containing an integer
            other_config : rstp-port-admin-edge
                                     optional string, either true or false
            other_config : rstp-port-auto-edge
                                     optional string, either true or false
            other_config : rstp-port-mcheck
                                     optional string, either true or false
         RSTP Status:
            rstp_status : rstp_port_id
                                     optional string
            rstp_status : rstp_port_role
                                     optional  string,  one  of Backup, Desig
                                     nated, Alternate, Root, or Disabled
            rstp_status : rstp_port_state
                                     optional string, one  of  Disabled,  Dis
                                     carding, Forwarding, or Learning
            rstp_status : rstp_designated_bridge_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_designated_path_cost
                                     optional string, containing an integer
         RSTP Statistics:
            rstp_statistics : rstp_tx_count
                                     optional integer
            rstp_statistics : rstp_rx_count
                                     optional integer
            rstp_statistics : rstp_error_count
                                     optional integer
            rstp_statistics : rstp_uptime
                                     optional integer
       Multicast Snooping:
         other_config : mcast-snooping-flood
                                     optional string, either true or false
         other_config : mcast-snooping-flood-reports
                                     optional string, either true or false
       Other Features:
         qos                         optional QoS
         mac                         optional string
         fake_bridge                 boolean
         external_ids : fake-bridge-id-*
                                     optional string
         other_config : transient    optional string, either true or false
       bond_active_slave             optional string
       Port Statistics:
         Statistics: STP transmit and receive counters:
            statistics : stp_tx_count
                                     optional integer
            statistics : stp_rx_count
                                     optional integer
            statistics : stp_error_count
                                     optional integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       name: immutable string (must be unique within table)
              Port  name.   Should  be  alphanumeric  and no more than about 8
              bytes long.  May be the same as the  interface  name,  for  non-
              bonded  ports.   Must  otherwise  be  unique  among the names of
              ports, interfaces, and bridges on a host.

       interfaces: set of 1 or more Interfaces
              The port’s interfaces.  If there is more than  one,  this  is  a
              bonded Port.

     VLAN Configuration:
       Bridge ports support the following types of VLAN configuration:

              trunk  A  trunk  port  carries  packets on one or more specified
                     VLANs specified in the trunks  column  (often,  on  every
                     VLAN).  A packet that ingresses on a trunk port is in the
                     VLAN specified in its 802.1Q header, or  VLAN  0  if  the
                     packet  has  no  802.1Q  header.   A packet that egresses
                     through a trunk port will have an 802.1Q header if it has
                     a nonzero VLAN ID.

                     Any  packet  that ingresses on a trunk port tagged with a
                     VLAN that the port does not trunk is dropped.

              access An access port carries packets on exactly one VLAN speci‐
                     fied  in  the tag column.  Packets egressing on an access
                     port have no 802.1Q header.

                     Any packet with an 802.1Q header with a nonzero  VLAN  ID
                     that  ingresses  on an access port is dropped, regardless
                     of whether the VLAN ID in the header is the access port’s
                     VLAN ID.

              native-tagged
                     A  native-tagged  port  resembles  a trunk port, with the
                     exception that a packet without  an  802.1Q  header  that
                     ingresses  on  a  native-tagged  port  is in the ``native
                     VLAN’’ (specified in the tag column).

              native-untagged
                     A native-untagged port resembles  a  native-tagged  port,
                     with  the  exception  that  a  packet  that egresses on a
                     native-untagged port in the native VLAN will not have  an
                     802.1Q header.

       A  packet  will only egress through bridge ports that carry the VLAN of
       the packet, as described by the rules above.

       vlan_mode:   optional   string,   one   of    access,    native-tagged,
       native-untagged, or trunk
              The VLAN mode of the port, as described above.  When this column
              is empty, a default mode is selected as follows:

              ·      If tag contains a value, the port is an access port.  The
                     trunks column should be empty.

              ·      Otherwise,  the  port is a trunk port.  The trunks column
                     value is honored if it is present.

       tag: optional integer, in range 0 to 4,095
              For an access port, the port’s implicitly tagged  VLAN.   For  a
              native-tagged  or  native-untagged port, the port’s native VLAN.
              Must be empty if this is a trunk port.

       trunks: set of up to 4,096 integers, in range 0 to 4,095
              For a trunk, native-tagged, or native-untagged port, the  802.1Q
              VLAN  or  VLANs  that this port trunks; if it is empty, then the
              port trunks all VLANs.  Must be empty if this is an access port.

              A native-tagged or native-untagged port always trunks its native
              VLAN, regardless of whether trunks includes that VLAN.

       other_config : priority-tags: optional string, either true or false
              An 802.1Q header contains two important pieces of information: a
              VLAN ID and a priority.  A frame with a zero VLAN ID,  called  a
              ``priority-tagged’’  frame,  is  supposed to be treated the same
              way as a frame without an 802.1Q header at all (except  for  the
              priority).

              However,  some network elements ignore any frame that has 802.1Q
              header at all, even when the VLAN ID  is  zero.   Therefore,  by
              default  Open  vSwitch  does  not output priority-tagged frames,
              instead omitting the 802.1Q header entirely if the  VLAN  ID  is
              zero.   Set this key to true to enable priority-tagged frames on
              a port.

              Regardless of this setting, Open vSwitch omits the 802.1Q header
              on output if both the VLAN ID and priority would be zero.

              All frames output to native-tagged ports have a nonzero VLAN ID,
              so this setting is not meaningful on native-tagged ports.

     Bonding Configuration:
       A port that has more than one interface is a ``bonded  port.’’  Bonding
       allows for load balancing and fail-over.

       The  following  types  of  bonding  will work with any kind of upstream
       switch.  On the upstream switch, do not configure the interfaces  as  a
       bond:

              balance-slb
                     Balances  flows  among slaves based on source MAC address
                     and output VLAN, with  periodic  rebalancing  as  traffic
                     patterns change.

              active-backup
                     Assigns  all flows to one slave, failing over to a backup
                     slave when the active slave is  disabled.   This  is  the
                     only bonding mode in which interfaces may be plugged into
                     different upstream switches.

       The following modes require the upstream switch to support 802.3ad with
       successful  LACP  negotiation. If LACP negotiation fails and other-con‐
       fig:lacp-fallback-ab is true, then active-backup mode is used:

              balance-tcp
                     Balances flows among slaves based on L2, L3, and L4  pro‐
                     tocol  information  such  as  destination MAC address, IP
                     address, and TCP port.

       These columns apply only to bonded ports.  Their values  are  otherwise
       ignored.

       bond_mode:  optional string, one of active-backup, balance-tcp, or bal
       ance-slb
              The type of  bonding  used  for  a  bonded  port.   Defaults  to
              active-backup if unset.

       other_config : bond-hash-basis: optional string, containing an integer
              An  integer  hashed along with flows when choosing output slaves
              in load  balanced  bonds.   When  changed,  all  flows  will  be
              assigned  different hash values possibly causing slave selection
              decisions to change.  Does not affect bonding modes which do not
              employ load balancing such as active-backup.

     Link Failure Detection:
       An  important  part of link bonding is detecting that links are down so
       that they may be disabled.  These settings determine how  Open  vSwitch
       detects link failure.

       other_config : bond-detect-mode: optional string, either miimon or car
       rier
              The means used to detect link  failures.   Defaults  to  carrier
              which  uses  each  interface’s carrier to detect failures.  When
              set to miimon, will check for failures by  polling  each  inter‐
              face’s MII.

       other_config  :  bond-miimon-interval:  optional  string, containing an
       integer
              The interval, in milliseconds, between  successive  attempts  to
              poll  each  interface’s  MII.   Relevant  only  when  other_con
              fig:bond-detect-mode is miimon.

       bond_updelay: integer
              The number of milliseconds for which the link must stay up on an
              interface  before the interface is considered to be up.  Specify
              0 to enable the interface immediately.

              This setting is honored only when at least one bonded  interface
              is  already  enabled.   When no interfaces are enabled, then the
              first bond interface to come up is enabled immediately.

       bond_downdelay: integer
              The number of milliseconds for which the link must stay down  on
              an  interface  before  the  interface  is considered to be down.
              Specify 0 to disable the interface immediately.

     LACP Configuration:
       LACP, the Link Aggregation Control Protocol, is an IEEE  standard  that
       allows switches to automatically detect that they are connected by mul‐
       tiple links and aggregate across those links.  These  settings  control
       LACP behavior.

       lacp: optional string, one of active, passive, or off
              Configures  LACP  on  this port.  LACP allows directly connected
              switches to negotiate which links may be bonded.   LACP  may  be
              enabled on non-bonded ports for the benefit of any switches they
              may be connected to.  active ports are allowed to initiate  LACP
              negotiations.   passive ports are allowed to participate in LACP
              negotiations initiated by a remote switch, but  not  allowed  to
              initiate  such negotiations themselves.  If LACP is enabled on a
              port whose partner switch does not support LACP, the  bond  will
              be  disabled,  unless  other-config:lacp-fallback-ab  is  set to
              true.  Defaults to off if unset.

       other_config : lacp-system-id: optional string
              The LACP system ID of this Port.  The system ID of a  LACP  bond
              is  used  to identify itself to its partners.  Must be a nonzero
              MAC address. Defaults to the bridge Ethernet address if unset.

       other_config : lacp-system-priority:  optional  string,  containing  an
       integer, in range 1 to 65,535
              The  LACP  system  priority of this Port.  In LACP negotiations,
              link status decisions are made by the system  with  the  numeri‐
              cally lower priority.

       other_config : lacp-time: optional string, either slow or fast
              The  LACP  timing which should be used on this Port.  By default
              slow is used.  When configured to be fast  LACP  heartbeats  are
              requested  at  a  rate  of  once per second causing connectivity
              problems to be detected more quickly.  In slow mode,  heartbeats
              are requested at a rate of once every 30 seconds.

       other_config : lacp-fallback-ab: optional string, either true or false
              Determines the behavior of openvswitch bond in LACP mode. If the
              partner switch does not support LACP,  setting  this  option  to
              true  allows  openvswitch  to  fallback to active-backup. If the
              option is set to false, the bond will be disabled. In  both  the
              cases,  once  the partner switch is configured to LACP mode, the
              bond will use LACP.

     Rebalancing Configuration:
       These settings control behavior when a bond is in balance-slb  or  bal
       ance-tcp mode.

       other_config  : bond-rebalance-interval: optional string, containing an
       integer, in range 0 to 10,000
              For a load balanced bonded  port,  the  number  of  milliseconds
              between  successive  attempts to rebalance the bond, that is, to
              move flows from one interface on  the  bond  to  another  in  an
              attempt to keep usage of each interface roughly equal.  If zero,
              load balancing is disabled on the bond (link failure still cause
              flows  to  move).   If  less than 1000ms, the rebalance interval
              will be 1000ms.

       bond_fake_iface: boolean
              For a bonded port, whether to create a fake  internal  interface
              with  the  name  of  the  port.  Use only for compatibility with
              legacy software that requires this.

     Spanning Tree Protocol:
       The configuration here is only meaningful, and the status is only popu‐
       lated, when 802.1D-1998 Spanning Tree Protocol is enabled on the port’s
       Bridge with its stp_enable column.

     STP Configuration:

       other_config : stp-enable: optional string, either true or false
              When STP is enabled on a bridge, it is enabled by default on all
              of  the  bridge’s  ports except bond, internal, and mirror ports
              (which do not work with STP).  If this column’s value is  false,
              STP is disabled on the port.

       other_config : stp-port-num: optional string, containing an integer, in
       range 1 to 255
              The port number used for the lower 8 bits of  the  port-id.   By
              default,  the  numbers  will  be assigned automatically.  If any
              port’s number is manually configured on a bridge, then they must
              all be.

       other_config  : stp-port-priority: optional string, containing an inte‐
       ger, in range 0 to 255
              The port’s relative priority value for determining the root port
              (the  upper 8 bits of the port-id).  A port with a lower port-id
              will be chosen as the root port.  By default,  the  priority  is
              0x80.

       other_config  :  stp-path-cost: optional string, containing an integer,
       in range 0 to 65,535
              Spanning tree path cost for the port.  A lower number  indicates
              a  faster  link.   By  default, the cost is based on the maximum
              speed of the link.

     STP Status:

       status : stp_port_id: optional string
              The port ID used in spanning tree advertisements for this  port,
              as  4  hex  digits.  Configuring the port ID is described in the
              stp-port-num and stp-port-priority keys of the other_config sec‐
              tion earlier.

       status  :  stp_state:  optional  string,  one  of disabled, forwarding,
       learning, listening, or blocking
              STP state of the port.

       status : stp_sec_in_state: optional string, containing an  integer,  at
       least 0
              The  amount of time this port has been in the current STP state,
              in seconds.

       status : stp_role: optional string, one of  designated,  alternate,  or
       root
              STP role of the port.

     Rapid Spanning Tree Protocol:
       The  configuration  here is only meaningful, and the status and statis‐
       tics are only populated, when 802.1D-1998  Spanning  Tree  Protocol  is
       enabled on the port’s Bridge with its stp_enable column.

     RSTP Configuration:

       other_config : rstp-enable: optional string, either true or false
              When  RSTP  is  enabled on a bridge, it is enabled by default on
              all of the bridge’s ports  except  bond,  internal,  and  mirror
              ports  (which do not work with RSTP).  If this column’s value is
              false, RSTP is disabled on the port.

       other_config : rstp-port-priority: optional string, containing an inte‐
       ger, in range 0 to 240
              The  port’s  relative  priority  value  for determining the root
              port, in multiples of 16.  By default, the port priority is 0x80
              (128).   Any value in the lower 4 bits is rounded off.  The sig‐
              nificant upper 4 bits become the upper 4 bits of the port-id.  A
              port with the lowest port-id is elected as the root.

       other_config  :  rstp-port-num: optional string, containing an integer,
       in range 1 to 4,095
              The local RSTP port number, used as the lower  12  bits  of  the
              port-id.   By  default  the  port numbers are assigned automati‐
              cally, and typically may not correspond  to  the  OpenFlow  port
              numbers.  A port with the lowest port-id is elected as the root.

       other_config  :  rstp-port-path-cost:  optional  string,  containing an
       integer
              The port path cost.  The Port’s contribution,  when  it  is  the
              Root Port, to the Root Path Cost for the Bridge.  By default the
              cost is automatically calculated from the port’s speed.

       other_config : rstp-port-admin-edge: optional string,  either  true  or
       false
              The admin edge port parameter for the Port.  Default is false.

       other_config  :  rstp-port-auto-edge:  optional  string, either true or
       false
              The auto edge port parameter for the Port.  Default is true.

       other_config : rstp-port-mcheck: optional string, either true or false
              The mcheck port parameter for the Port.  Default is false.   May
              be  set  to  force  the Port Protocol Migration state machine to
              transmit RST BPDUs for a MigrateTime period, to test whether all
              STP  Bridges  on the attached LAN have been removed and the Port
              can continue to transmit RSTP  BPDUs.   Setting  mcheck  has  no
              effect if the Bridge is operating in STP Compatibility mode.

              Changing  the  value from true to false has no effect, but needs
              to be done if this behavior is to be triggered again  by  subse‐
              quently changing the value from false to true.

     RSTP Status:

       rstp_status : rstp_port_id: optional string
              The  port ID used in spanning tree advertisements for this port,
              as 4 hex digits.  Configuring the port ID is  described  in  the
              rstp-port-num  and  rstp-port-priority  keys of the other_config
              section earlier.

       rstp_status : rstp_port_role: optional string, one  of  Backup,  Desig
       nated, Alternate, Root, or Disabled
              RSTP role of the port.

       rstp_status  :  rstp_port_state: optional string, one of Disabled, Dis
       carding, Forwarding, or Learning
              RSTP state of the port.

       rstp_status : rstp_designated_bridge_id: optional string
              The port’s RSTP designated  bridge  ID,  in  the  same  form  as
              rstp_status:rstp_bridge_id in the Bridge table.

       rstp_status : rstp_designated_port_id: optional string
              The port’s RSTP designated port ID, as 4 hex digits.

       rstp_status : rstp_designated_path_cost: optional string, containing an
       integer
              The port’s RSTP designated path cost.  Lower is better.

     RSTP Statistics:

       rstp_statistics : rstp_tx_count: optional integer
              Number of RSTP BPDUs transmitted through this port.

       rstp_statistics : rstp_rx_count: optional integer
              Number of valid RSTP BPDUs received by this port.

       rstp_statistics : rstp_error_count: optional integer
              Number of invalid RSTP BPDUs received by this port.

       rstp_statistics : rstp_uptime: optional integer
              The duration covered by the other RSTP statistics, in seconds.

     Multicast Snooping:

       other_config : mcast-snooping-flood: optional string,  either  true  or
       false
              If  set to true, multicast packets (except Reports) are uncondi‐
              tionally forwarded to the specific port.

       other_config : mcast-snooping-flood-reports:  optional  string,  either
       true or false
              If  set to true, multicast Reports are unconditionally forwarded
              to the specific port.

     Other Features:

       qos: optional QoS
              Quality of Service configuration for this port.

       mac: optional string
              The MAC address to use for this port for the purpose of choosing
              the  bridge’s  MAC  address.   This  column does not necessarily
              reflect the port’s actual  MAC  address,  nor  will  setting  it
              change the port’s actual MAC address.

       fake_bridge: boolean
              Does this port represent a sub-bridge for its tagged VLAN within
              the Bridge?  See ovs-vsctl(8) for more information.

       external_ids : fake-bridge-id-*: optional string
              External IDs for a fake bridge (see the fake_bridge column)  are
              defined   by   prefixing   a   Bridge   external_ids   key  with
              fake-bridge-, e.g. fake-bridge-xs-network-uuids.

       other_config : transient: optional string, either true or false
              If set to true, the port will  be  removed  when  ovs-ctl  start
              --delete-transient-ports is used.

       bond_active_slave: optional string
              For  a bonded port, record the mac address of the current active
              slave.

     Port Statistics:
       Key-value pairs that report port statistics.  The update period is con‐
       trolled  by  other_config:stats-update-interval in the Open_vSwitch ta‐
       ble.

     Statistics: STP transmit and receive counters:

       statistics : stp_tx_count: optional integer
              Number of STP BPDUs sent on  this  port  by  the  spanning  tree
              library.

       statistics : stp_rx_count: optional integer
              Number  of  STP  BPDUs received on this port and accepted by the
              spanning tree library.

       statistics : stp_error_count: optional integer
              Number of bad STP  BPDUs  received  on  this  port.   Bad  BPDUs
              include runt packets and those with an unexpected protocol ID.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Interface TABLE
       An interface within a Port.

   Summary:
       Core Features:
         name                        immutable string (must be  unique  within
                                     table)
         ifindex                     optional   integer,   in   range   0   to
                                     4,294,967,295
         mac_in_use                  optional string
         mac                         optional string
         error                       optional string
         OpenFlow Port Number:
            ofport                   optional integer
            ofport_request           optional integer, in range 1 to 65,279
       System-Specific Details:
         type                        string
       Tunnel Options:
         options : remote_ip         optional string
         options : local_ip          optional string
         options : in_key            optional string
         options : out_key           optional string
         options : key               optional string
         options : tos               optional string
         options : ttl               optional string
         options : df_default        optional string, either true or false
         Tunnel Options: vxlan only:
            options : exts           optional string
         Tunnel Options: gre, ipsec_gre, geneve, and vxlan:
            options : csum           optional string, either true or false
         Tunnel Options: ipsec_gre only:
            options : peer_cert      optional string
            options : certificate    optional string
            options : private_key    optional string
            options : psk            optional string
       Patch Options:
         options : peer              optional string
       Interface Status:
         admin_state                 optional string, either down or up
         link_state                  optional string, either down or up
         link_resets                 optional integer
         link_speed                  optional integer
         duplex                      optional string, either full or half
         mtu                         optional integer
         lacp_current                optional boolean
         status                      map of string-string pairs
         status : driver_name        optional string
         status : driver_version     optional string
         status : firmware_version   optional string
         status : source_ip          optional string
         status : tunnel_egress_iface
                                     optional string
         status : tunnel_egress_iface_carrier
                                     optional string, either down or up
       Statistics:
         Statistics: Successful transmit and receive counters:
            statistics : rx_packets  optional integer
            statistics : rx_bytes    optional integer
            statistics : tx_packets  optional integer
            statistics : tx_bytes    optional integer
         Statistics: Receive errors:
            statistics : rx_dropped  optional integer
            statistics : rx_frame_err
                                     optional integer
            statistics : rx_over_err optional integer
            statistics : rx_crc_err  optional integer
            statistics : rx_errors   optional integer
         Statistics: Transmit errors:
            statistics : tx_dropped  optional integer
            statistics : collisions  optional integer
            statistics : tx_errors   optional integer
       Ingress Policing:
         ingress_policing_rate       integer, at least 0
         ingress_policing_burst      integer, at least 0
       Bidirectional Forwarding Detection (BFD):
         BFD Configuration:
            bfd : enable             optional string, either true or false
            bfd : min_rx             optional string, containing  an  integer,
                                     at least 1
            bfd : min_tx             optional  string,  containing an integer,
                                     at least 1
            bfd : decay_min_rx       optional string, containing an integer
            bfd : forwarding_if_rx   optional string, either true or false
            bfd : cpath_down         optional string, either true or false
            bfd : check_tnl_key      optional string, either true or false
            bfd : bfd_local_src_mac  optional string
            bfd : bfd_local_dst_mac  optional string
            bfd : bfd_remote_dst_mac optional string
            bfd : bfd_src_ip         optional string
            bfd : bfd_dst_ip         optional string
         BFD Status:
            bfd_status : state       optional string, one of down,  init,  up,
                                     or admin_down
            bfd_status : forwarding  optional string, either true or false
            bfd_status : diagnostic  optional string
            bfd_status : remote_state
                                     optional  string,  one of down, init, up,
                                     or admin_down
            bfd_status : remote_diagnostic
                                     optional string
            bfd_status : flap_count  optional string, containing  an  integer,
                                     at least 0
       Connectivity Fault Management:
         cfm_mpid                    optional integer
         cfm_flap_count              optional integer
         cfm_fault                   optional boolean
         cfm_fault_status : recv     none
         cfm_fault_status : rdi      none
         cfm_fault_status : maid     none
         cfm_fault_status : loopback
                                     none
         cfm_fault_status : overflow
                                     none
         cfm_fault_status : override
                                     none
         cfm_fault_status : interval
                                     none
         cfm_remote_opstate          optional string, either down or up
         cfm_health                  optional integer, in range 0 to 100
         cfm_remote_mpids            set of integers
         other_config : cfm_interval
                                     optional string, containing an integer
         other_config : cfm_extended
                                     optional string, either true or false
         other_config : cfm_demand   optional string, either true or false
         other_config : cfm_opstate  optional string, either down or up
         other_config : cfm_ccm_vlan
                                     optional  string,  containing an integer,
                                     in range 1 to 4,095
         other_config : cfm_ccm_pcp  optional string, containing  an  integer,
                                     in range 1 to 7
       Bonding Configuration:
         other_config : lacp-port-id
                                     optional  string,  containing an integer,
                                     in range 1 to 65,535
         other_config : lacp-port-priority
                                     optional string, containing  an  integer,
                                     in range 1 to 65,535
         other_config : lacp-aggregation-key
                                     optional  string,  containing an integer,
                                     in range 1 to 65,535
       Virtual Machine Identifiers:
         external_ids : attached-mac
                                     optional string
         external_ids : iface-id     optional string
         external_ids : iface-status
                                     optional string, either active  or  inac
                                     tive
         external_ids : xs-vif-uuid  optional string
         external_ids : xs-network-uuid
                                     optional string
         external_ids : vm-id        optional string
         external_ids : xs-vm-uuid   optional string
       VLAN Splinters:
         other_config : enable-vlan-splinters
                                     optional string, either true or false
       Auto Attach Configuration:
         lldp : enable               optional string, either true or false
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Interface name.  Should be alphanumeric and no more than about 8
              bytes long.  May be the same as the port  name,  for  non-bonded
              ports.   Must  otherwise  be  unique  among  the names of ports,
              interfaces, and bridges on a host.

       ifindex: optional integer, in range 0 to 4,294,967,295
              A positive interface index as defined for SNMP  MIB-II  in  RFCs
              1213  and  2863,  if  the  interface  has one, otherwise 0.  The
              ifindex is useful for seamless integration with  protocols  such
              as SNMP and sFlow.

       mac_in_use: optional string
              The MAC address in use by this interface.

       mac: optional string
              Ethernet  address  to set for this interface.  If unset then the
              default MAC address is used:

              ·      For the local interface, the default is  the  lowest-num‐
                     bered  MAC  address  among the other bridge ports, either
                     the value of the mac in its Port record, if set,  or  its
                     actual  MAC (for bonded ports, the MAC of its slave whose
                     name is first in alphabetical order).  Internal ports and
                     bridge ports that are used as port mirroring destinations
                     (see the Mirror table) are ignored.

              ·      For other internal interfaces, the default  MAC  is  ran‐
                     domly generated.

              ·      External  interfaces typically have a MAC address associ‐
                     ated with their hardware.

              Some  interfaces  may  not  have  a  software-controllable   MAC
              address.

       error: optional string
              If  the  configuration of the port failed, as indicated by -1 in
              ofport, Open vSwitch sets this column to an error description in
              human  readable  form.  Otherwise, Open vSwitch clears this col‐
              umn.

     OpenFlow Port Number:
       When a client adds a new interface, Open vSwitch  chooses  an  OpenFlow
       port  number  for the new port.  If the client that adds the port fills
       in ofport_request, then Open vSwitch tries to  use  its  value  as  the
       OpenFlow  port  number.   Otherwise, or if the requested port number is
       already in use or cannot be used for another reason, Open vSwitch auto‐
       matically  assigns a free port number.  Regardless of how the port num‐
       ber was obtained, Open vSwitch then reports in ofport the  port  number
       actually assigned.

       Open  vSwitch  limits the port numbers that it automatically assigns to
       the range 1 through 32,767, inclusive.  Controllers therefore have free
       use of ports 32,768 and up.

       ofport: optional integer
              OpenFlow port number for this interface.  Open vSwitch sets this
              column’s value, so other clients should treat it as read-only.

              The OpenFlow ``local’’ port (OFPP_LOCAL) is 65,534.   The  other
              valid  port  numbers  are  in  the range 1 to 65,279, inclusive.
              Value -1 indicates an error adding the interface.

       ofport_request: optional integer, in range 1 to 65,279
              Requested OpenFlow port number for this interface.

              A client should ideally set this  column’s  value  in  the  same
              database transaction that it uses to create the interface.  Open
              vSwitch version 2.1 and later will honor a later request  for  a
              specific  port  number,  althuogh  it  might  confuse  some con‐
              trollers: OpenFlow does not have a way to announce a port number
              change,  so  Open  vSwitch represents it over OpenFlow as a port
              deletion followed immediately by a port addition.

              If ofport_request is set or changed to some other  port’s  auto‐
              matically  assigned port number, Open vSwitch chooses a new port
              number for the latter port.

     System-Specific Details:

       type: string
              The  interface  type.   The  types  supported  by  a  particular
              instance of Open vSwitch are listed in the iface_types column in
              the Open_vSwitch table.  The following types are defined:

              system An ordinary network device, e.g. eth0  on  Linux.   Some‐
                     times  referred  to as ``external interfaces’’ since they
                     are generally connected to hardware external to  that  on
                     which the Open vSwitch is running.  The empty string is a
                     synonym for system.

              internal
                     A simulated network device that sends and receives  traf‐
                     fic.  An internal interface whose name is the same as its
                     bridge’s name is called the ``local interface.’’  It does
                     not  make  sense  to  bond  an internal interface, so the
                     terms ``port’’ and ``interface’’ are  often  used  impre‐
                     cisely for internal interfaces.

              tap    A TUN/TAP device managed by Open vSwitch.

              geneve An             Ethernet            over            Geneve
                     (http://tools.ietf.org/html/draft-ietf-nvo3-geneve-00)
                     IPv4  tunnel.  A description of how to match and set Gen‐
                     eve options can be found in the ovs-ofctl manual page.

              gre    An Ethernet over RFC 2890 Generic  Routing  Encapsulation
                     over IPv4 tunnel.

              ipsec_gre
                     An  Ethernet  over RFC 2890 Generic Routing Encapsulation
                     over IPv4 IPsec tunnel.

              vxlan  An Ethernet tunnel  over  the  UDP-based  VXLAN  protocol
                     described in RFC 7348.

                     Open  vSwitch uses UDP destination port 4789.  The source
                     port used for VXLAN traffic varies on  a  per-flow  basis
                     and is in the ephemeral port range.

              lisp   A  layer  3 tunnel over the experimental, UDP-based Loca‐
                     tor/ID Separation Protocol (RFC 6830).

                     Only IPv4 and IPv6 packets are supported by the protocol,
                     and  they  are  sent  and  received  without  an Ethernet
                     header.  Traffic to/from LISP ports  is  expected  to  be
                     configured  explicitly, and the ports are not intended to
                     participate in learning based switching.  As  such,  they
                     are always excluded from packet flooding.

              stt    The  Stateless  TCP  Tunnel  (STT) is particularly useful
                     when tunnel endpoints are in end-systems, as it  utilizes
                     the  capabilities  of standard network interface cards to
                     improve performance.   STT  utilizes  a  TCP-like  header
                     inside  the IP header. It is stateless, i.e., there is no
                     TCP connection state of any kind associated with the tun‐
                     nel.   The  TCP-like header is used to leverage the capa‐
                     bilities of existing network interface cards, but  should
                     not  be  interpreted  as  implying any sort of connection
                     state between endpoints.  Since the STT protocol does not
                     engage  in the usual TCP 3-way handshake, so it will have
                     difficulty traversing stateful firewalls.   The  protocol
                     is  documented  at  http://www.ietf.org/archive/id/draft-
                     davie-stt-06.txt All traffic uses a  default  destination
                     port of 7471. STT is only available in kernel datapath on
                     kernel 3.5 or newer.

              patch  A pair of virtual devices that act as a patch cable.

              null   An ignored interface. Deprecated and slated  for  removal
                     in February 2013.

     Tunnel Options:
       These  options apply to interfaces with type of geneve, gre, ipsec_gre,
       vxlan, lisp and stt.

       Each tunnel must be uniquely identified by  the  combination  of  type,
       options:remote_ip,  options:local_ip, and options:in_key.  If two ports
       are defined that are the same except one has an optional identifier and
       the   other   does  not,  the  more  specific  one  is  matched  first.
       options:in_key is considered more specific than options:local_ip  if  a
       port defines one and another port defines the other.

       options : remote_ip: optional string
              Required.  The remote tunnel endpoint, one of:

              ·      An  IPv4  address  (not  a DNS name), e.g. 192.168.0.123.
                     Only unicast endpoints are supported.

              ·      The word flow.   The  tunnel  accepts  packets  from  any
                     remote  tunnel  endpoint.  To process only packets from a
                     specific remote tunnel endpoint,  the  flow  entries  may
                     match  on  the  tun_src field.  When sending packets to a
                     remote_ip=flow tunnel, the flow actions  must  explicitly
                     set  the  tun_dst  field to the IP address of the desired
                     remote tunnel endpoint, e.g. with a set_field action.

              The remote tunnel endpoint for any packet received from a tunnel
              is  available  in the tun_src field for matching in the flow ta‐
              ble.

       options : local_ip: optional string
              Optional.  The tunnel destination IP that received packets  must
              match.  Default is to match all addresses.  If specified, may be
              one of:

              ·      An IPv4 address (not a DNS name), e.g. 192.168.12.3.

              ·      The word flow.  The tunnel accepts packets sent to any of
                     the  local  IP  addresses  of the system running OVS.  To
                     process only packets sent to a specific IP  address,  the
                     flow  entries may match on the tun_dst field.  When send‐
                     ing packets to a local_ip=flow tunnel, the  flow  actions
                     may  explicitly  set  the tun_src field to the desired IP
                     address, e.g. with a set_field  action.   However,  while
                     routing  the  tunneled  packet  out, the local system may
                     override the specified address with the local IP  address
                     configured for the outgoing system interface.

                     This  option  is  valid  only for tunnels also configured
                     with the remote_ip=flow option.

              The tunnel destination IP address for any packet received from a
              tunnel  is  available  in  the tun_dst field for matching in the
              flow table.

       options : in_key: optional string
              Optional.  The key that received packets must contain, one of:

              ·      0.  The tunnel receives packets with no key or with a key
                     of 0.  This is equivalent to specifying no options:in_key
                     at all.

              ·      A positive 24-bit (for Geneve, VXLAN, and  LISP),  32-bit
                     (for  GRE)  or  64-bit  (for  STT)  number.   The  tunnel
                     receives only packets with the specified key.

              ·      The word flow.  The tunnel accepts packets with any  key.
                     The  key  will be placed in the tun_id field for matching
                     in the flow table.  The ovs-ofctl  manual  page  contains
                     additional  information about matching fields in OpenFlow
                     flows.

       options : out_key: optional string
              Optional.  The key to be set on outgoing packets, one of:

              ·      0.  Packets sent through the tunnel  will  have  no  key.
                     This  is  equivalent  to specifying no options:out_key at
                     all.

              ·      A positive 24-bit (for Geneve, VXLAN  and  LISP),  32-bit
                     (for  GRE)  or  64-bit  (for  STT)  number.  Packets sent
                     through the tunnel will have the specified key.

              ·      The word flow.  Packets sent through the tunnel will have
                     the  key  set using the set_tunnel Nicira OpenFlow vendor
                     extension (0 is used in the absence of an  action).   The
                     ovs-ofctl  manual  page  contains  additional information
                     about the Nicira OpenFlow vendor extensions.

       options : key: optional string
              Optional.  Shorthand to set in_key and out_key at the same time.

       options : tos: optional string
              Optional.  The value of the ToS bits to be set on  the  encapsu‐
              lating  packet.   ToS  is  interpreted as DSCP and ECN bits, ECN
              part must be zero.  It may also be the word  inherit,  in  which
              case  the ToS will be copied from the inner packet if it is IPv4
              or IPv6 (otherwise it will be 0).  The  ECN  fields  are  always
              inherited.  Default is 0.

       options : ttl: optional string
              Optional.   The  TTL  to be set on the encapsulating packet.  It
              may also be the word inherit, in which  case  the  TTL  will  be
              copied from the inner packet if it is IPv4 or IPv6 (otherwise it
              will be the system default, typically 64).  Default is the  sys‐
              tem default TTL.

       options : df_default: optional string, either true or false
              Optional.   If  enabled,  the  Don’t Fragment bit will be set on
              tunnel outer headers to allow path  MTU  discovery.  Default  is
              enabled; set to false to disable.

     Tunnel Options: vxlan only:

       options : exts: optional string
              Optional.   Comma separated list of optional VXLAN extensions to
              enable. The following extensions are supported:

              ·      gbp: VXLAN-GBP allows to transport the group policy  con‐
                     text of a packet across the VXLAN tunnel to other network
                     peers.  See  the  field  description  of  tun_gbp_id  and
                     tun_gbp_flags in ovs-ofctl(8) for additional information.
                     (https://tools.ietf.org/html/draft-smith-vxlan-group-pol
                     icy)

     Tunnel Options: gre, ipsec_gre, geneve, and vxlan:
       gre, ipsec_gre, geneve, and vxlan interfaces support these options.

       options : csum: optional string, either true or false
              Optional.   Compute  encapsulation  header  (either  GRE or UDP)
              checksums on outgoing packets.  Default is disabled, set to true
              to  enable.  Checksums present on incoming packets will be vali‐
              dated regardless of this setting.

              When using the upstream  Linux  kernel  module,  computation  of
              checksums for geneve and vxlan requires Linux kernel version 4.0
              or higher. gre supports  checksums  for  all  versions  of  Open
              vSwitch  that  support  GRE.  The out of tree kernel module dis‐
              tributed as part of OVS can compute all tunnel checksums on  any
              kernel version that it is compatible with.

              This  option  is supported for ipsec_gre, but not useful because
              GRE checksums are weaker than, and redundant with, IPsec payload
              authentication.

     Tunnel Options: ipsec_gre only:
       Only ipsec_gre interfaces support these options.

       options : peer_cert: optional string
              Required  for  certificate  authentication.  A string containing
              the peer’s certificate in PEM format.  Additionally  the  host’s
              certificate must be specified with the certificate option.

       options : certificate: optional string
              Required for certificate authentication.  The name of a PEM file
              containing a certificate that will be presented to the peer dur‐
              ing authentication.

       options : private_key: optional string
              Optional for certificate authentication.  The name of a PEM file
              containing the private key associated with certificate.  If cer
              tificate contains the private key, this option may be omitted.

       options : psk: optional string
              Required  for  pre-shared  key authentication.  Specifies a pre-
              shared key for authentication that must  be  identical  on  both
              sides of the tunnel.

     Patch Options:
       Only patch interfaces support these options.

       options : peer: optional string
              The  name of the Interface for the other side of the patch.  The
              named Interface’s own peer option must specify this  Interface’s
              name.  That is, the two patch interfaces must have reversed name
              and peer values.

     Interface Status:
       Status information about interfaces attached to bridges, updated  every
       5  seconds.   Not  all interfaces have all of these properties; virtual
       interfaces don’t have a link speed, for example.   Non-applicable  col‐
       umns will have empty values.

       admin_state: optional string, either down or up
              The administrative state of the physical network link.

       link_state: optional string, either down or up
              The  observed state of the physical network link.  This is ordi‐
              narily the link’s carrier status.  If the interface’s Port is  a
              bond configured for miimon monitoring, it is instead the network
              link’s miimon status.

       link_resets: optional integer
              The number of times Open vSwitch has observed the link_state  of
              this Interface change.

       link_speed: optional integer
              The negotiated speed of the physical network link.  Valid values
              are positive integers greater than 0.

       duplex: optional string, either full or half
              The duplex mode of the physical network link.

       mtu: optional integer
              The MTU (maximum transmission unit); i.e. the largest amount  of
              data  that  can  fit into a single Ethernet frame.  The standard
              Ethernet MTU is 1500 bytes.  Some physical media and many  kinds
              of virtual interfaces can be configured with higher MTUs.

              This column will be empty for an interface that does not have an
              MTU as, for example, some kinds of tunnels do not.

       lacp_current: optional boolean
              Boolean value indicating LACP status  for  this  interface.   If
              true, this interface has current LACP information about its LACP
              partner.  This information may be used to monitor the health  of
              interfaces in a LACP enabled port.  This column will be empty if
              LACP is not enabled.

       status: map of string-string pairs
              Key-value pairs that report port status.  Supported status  val‐
              ues  are  type-dependent;  some  interfaces may not have a valid
              status:driver_name, for example.

       status : driver_name: optional string
              The name of the device driver controlling the network adapter.

       status : driver_version: optional string
              The version string of the device driver controlling the  network
              adapter.

       status : firmware_version: optional string
              The  version string of the network adapter’s firmware, if avail‐
              able.

       status : source_ip: optional string
              The source IP address used for an IPv4 tunnel end-point, such as
              gre.

       status : tunnel_egress_iface: optional string
              Egress  interface for tunnels.  Currently only relevant for tun‐
              nels on Linux systems, this column will show  the  name  of  the
              interface  which is responsible for routing traffic destined for
              the configured options:remote_ip.  This  could  be  an  internal
              interface such as a bridge port.

       status  :  tunnel_egress_iface_carrier: optional string, either down or
       up
              Whether carrier is detected on status:tunnel_egress_iface.

     Statistics:
       Key-value pairs that report interface statistics.  The  current  imple‐
       mentation  updates  these  counters periodically.  The update period is
       controlled by other_config:stats-update-interval  in  the  Open_vSwitch
       table.   Future  implementations  may  update them when an interface is
       created, when they are queried (e.g. using an OVSDB select  operation),
       and  just  before an interface is deleted due to virtual interface hot-
       unplug or VM shutdown, and perhaps at other times, but not on any regu‐
       lar periodic basis.

       These  are  the  same  statistics  reported  by  OpenFlow in its struct
       ofp_port_stats structure.  If an interface does  not  support  a  given
       statistic, then that pair is omitted.

     Statistics: Successful transmit and receive counters:

       statistics : rx_packets: optional integer
              Number of received packets.

       statistics : rx_bytes: optional integer
              Number of received bytes.

       statistics : tx_packets: optional integer
              Number of transmitted packets.

       statistics : tx_bytes: optional integer
              Number of transmitted bytes.

     Statistics: Receive errors:

       statistics : rx_dropped: optional integer
              Number of packets dropped by RX.

       statistics : rx_frame_err: optional integer
              Number of frame alignment errors.

       statistics : rx_over_err: optional integer
              Number of packets with RX overrun.

       statistics : rx_crc_err: optional integer
              Number of CRC errors.

       statistics : rx_errors: optional integer
              Total number of receive errors, greater than or equal to the sum
              of the above.

     Statistics: Transmit errors:

       statistics : tx_dropped: optional integer
              Number of packets dropped by TX.

       statistics : collisions: optional integer
              Number of collisions.

       statistics : tx_errors: optional integer
              Total number of transmit errors, greater than or  equal  to  the
              sum of the above.

     Ingress Policing:
       These  settings  control  ingress policing for packets received on this
       interface.  On a physical interface, this  limits  the  rate  at  which
       traffic  is  allowed  into  the  system  from the outside; on a virtual
       interface (one connected to a virtual machine), this limits the rate at
       which the VM is able to transmit.

       Policing is a simple form of quality-of-service that simply drops pack‐
       ets received in excess of the configured rate.  Due to its  simplicity,
       policing  is  usually  less accurate and less effective than egress QoS
       (which is configured using the QoS and Queue tables).

       Policing is currently implemented only on Linux.  The Linux implementa‐
       tion uses a simple ``token bucket’’ approach:

              ·      The  size  of  the  bucket  corresponds to ingress_polic
                     ing_burst.  Initially the bucket is full.

              ·      Whenever a packet is received,  its  size  (converted  to
                     tokens)  is compared to the number of tokens currently in
                     the bucket.  If the required number of tokens are  avail‐
                     able, they are removed and the packet is forwarded.  Oth‐
                     erwise, the packet is dropped.

              ·      Whenever it is not full,  the  bucket  is  refilled  with
                     tokens at the rate specified by ingress_policing_rate.

       Policing  interacts  badly  with some network protocols, and especially
       with fragmented IP packets.   Suppose  that  there  is  enough  network
       activity to keep the bucket nearly empty all the time.  Then this token
       bucket algorithm will forward a single packet every so often, with  the
       period depending on packet size and on the configured rate.  All of the
       fragments of an IP packets are normally transmitted back-to-back, as  a
       group.   In  such  a  situation, therefore, only one of these fragments
       will be forwarded and the rest will be dropped.  IP  does  not  provide
       any  way for the intended recipient to ask for only the remaining frag‐
       ments.  In such a case there are two likely possibilities for what will
       happen next: either all of the fragments will eventually be retransmit‐
       ted (as TCP will do), in which case the same problem will recur, or the
       sender  will not realize that its packet has been dropped and data will
       simply be lost (as some UDP-based protocols will do).  Either  way,  it
       is possible that no forward progress will ever occur.

       ingress_policing_rate: integer, at least 0
              Maximum rate for data received on this interface, in kbps.  Data
              received faster than this  rate  is  dropped.   Set  to  0  (the
              default) to disable policing.

       ingress_policing_burst: integer, at least 0
              Maximum  burst  size for data received on this interface, in kb.
              The default burst size if set to 0 is 1000 kb.  This  value  has
              no effect if ingress_policing_rate is 0.

              Specifying  a  larger burst size lets the algorithm be more for‐
              giving, which is important for protocols like TCP that react se‐
              verely  to  dropped  packets.  The burst size should be at least
              the size of the interface’s MTU.  Specifying  a  value  that  is
              numerically  at  least  as large as 10% of ingress_policing_rate
              helps TCP come closer to achieving the full rate.

     Bidirectional Forwarding Detection (BFD):
       BFD, defined in RFC 5880 and RFC 5881, allows point-to-point  detection
       of connectivity failures by occasional transmission of BFD control mes‐
       sages.  Open vSwitch implements BFD to serve  as  a  more  popular  and
       standards compliant alternative to CFM.

       BFD  operates  by regularly transmitting BFD control messages at a rate
       negotiated independently in each direction.   Each  endpoint  specifies
       the  rate at which it expects to receive control messages, and the rate
       at which it is willing to transmit them.  Open vSwitch uses a detection
       multiplier  of  three,  meaning that an endpoint signals a connectivity
       fault if three consecutive BFD control messages fail to arrive.  In the
       case  of  a unidirectional connectivity issue, the system not receiving
       BFD control messages signals the problem to its peer in the messages it
       transmits.

       The  Open  vSwitch implementation of BFD aims to comply faithfully with
       RFC 5880 requirements.  Open vSwitch does not  implement  the  optional
       Authentication or ``Echo Mode’’ features.

     BFD Configuration:
       A  controller  sets  up key-value pairs in the bfd column to enable and
       configure BFD.

       bfd : enable: optional string, either true or false
              True to enable BFD on this Interface.   If  not  specified,  BFD
              will not be enabled by default.

       bfd : min_rx: optional string, containing an integer, at least 1
              The  shortest  interval, in milliseconds, at which this BFD ses‐
              sion offers to receive BFD control messages.   The  remote  end‐
              point may choose to send messages at a slower rate.  Defaults to
              1000.

       bfd : min_tx: optional string, containing an integer, at least 1
              The shortest interval, in milliseconds, at which this  BFD  ses‐
              sion is willing to transmit BFD control messages.  Messages will
              actually be transmitted at a slower rate if the remote  endpoint
              is  not willing to receive as quickly as specified.  Defaults to
              100.

       bfd : decay_min_rx: optional string, containing an integer
              An alternate receive interval, in  milliseconds,  that  must  be
              greater   than  or  equal  to  bfd:min_rx.   The  implementation
              switches from bfd:min_rx to bfd:decay_min_rx when  there  is  no
              obvious  incoming  data  traffic at the interface, to reduce the
              CPU and bandwidth cost of monitoring an  idle  interface.   This
              feature  may  be disabled by setting a value of 0.  This feature
              is reset whenever bfd:decay_min_rx or bfd:min_rx changes.

       bfd : forwarding_if_rx: optional string, either true or false
              When true, traffic received on the Interface is used to indicate
              the  capability  of  packet  I/O.  BFD control packets are still
              transmitted and received.  At least one BFD control packet  must
              be  received  every 100 * bfd:min_rx amount of time.  Otherwise,
              even if traffic are received, the bfd:forwarding will be false.

       bfd : cpath_down: optional string, either true or false
              Set to true to notify the remote endpoint  that  traffic  should
              not  be  forwarded  to  this system for some reason other than a
              connectivty failure on the interface being monitored.  The typi‐
              cal  underlying  reason  is ``concatenated path down,’’ that is,
              that connectivity beyond the local system is down.  Defaults  to
              false.

       bfd : check_tnl_key: optional string, either true or false
              Set to true to make BFD accept only control messages with a tun‐
              nel key of zero.  By default, BFD accepts control messages  with
              any tunnel key.

       bfd : bfd_local_src_mac: optional string
              Set  to an Ethernet address in the form xx:xx:xx:xx:xx:xx to set
              the MAC used as source for transmitted BFD packets.  The default
              is the mac address of the BFD enabled interface.

       bfd : bfd_local_dst_mac: optional string
              Set  to an Ethernet address in the form xx:xx:xx:xx:xx:xx to set
              the MAC used as destination for transmitted  BFD  packets.   The
              default is 00:23:20:00:00:01.

       bfd : bfd_remote_dst_mac: optional string
              Set  to an Ethernet address in the form xx:xx:xx:xx:xx:xx to set
              the MAC used for checking the destination of received BFD  pack‐
              ets.  Packets with different destination MAC will not be consid‐
              ered as BFD packets.   If  not  specified  the  destination  MAC
              address of received BFD packets are not checked.

       bfd : bfd_src_ip: optional string
              Set  to an IPv4 address to set the IP address used as source for
              transmitted BFD packets.  The default is 169.254.1.1.

       bfd : bfd_dst_ip: optional string
              Set to an IPv4 address to set the IP address used as destination
              for transmitted BFD packets.  The default is 169.254.1.0.

     BFD Status:
       The  switch sets key-value pairs in the bfd_status column to report the
       status of BFD on  this  interface.   When  BFD  is  not  enabled,  with
       bfd:enable, the switch clears all key-value pairs from bfd_status.

       bfd_status  :  state:  optional  string,  one  of  down,  init,  up, or
       admin_down
              Reports the state of the BFD session.  The BFD session is  fully
              healthy and negotiated if UP.

       bfd_status : forwarding: optional string, either true or false
              Reports  whether  the BFD session believes this Interface may be
              used to forward traffic.  Typically this means the local session
              is signaling UP, and the remote system isn’t signaling a problem
              such as concatenated path down.

       bfd_status : diagnostic: optional string
              A diagnostic code specifying the local system’s reason  for  the
              last  change in session state. The error messages are defined in
              section 4.1 of [RFC 5880].

       bfd_status : remote_state: optional string, one of down, init,  up,  or
       admin_down
              Reports the state of the remote endpoint’s BFD session.

       bfd_status : remote_diagnostic: optional string
              A  diagnostic code specifying the remote system’s reason for the
              last change in session state. The error messages are defined  in
              section 4.1 of [RFC 5880].

       bfd_status  :  flap_count:  optional  string, containing an integer, at
       least 0
              Counts the number of bfd_status:forwarding flaps since start.  A
              flap  is  considered  as  a  change of the bfd_status:forwarding
              value.

     Connectivity Fault Management:
       802.1ag Connectivity Fault Management (CFM) allows a group  of  Mainte‐
       nance Points (MPs) called a Maintenance Association (MA) to detect con‐
       nectivity problems with each other.  MPs within a MA should  have  com‐
       plete  and  exclusive interconnectivity.  This is verified by occasion‐
       ally broadcasting Continuity Check Messages (CCMs)  at  a  configurable
       transmission interval.

       According  to  the 802.1ag specification, each Maintenance Point should
       be configured out-of-band with a list of Remote Maintenance  Points  it
       should  have connectivity to.  Open vSwitch differs from the specifica‐
       tion in this area.  It simply assumes the link is faulted if no  Remote
       Maintenance  Points  are reachable, and considers it not faulted other‐
       wise.

       When operating over tunnels which have no in_key, or an in_key of flow.
       CFM will only accept CCMs with a tunnel key of zero.

       cfm_mpid: optional integer
              A  Maintenance Point ID (MPID) uniquely identifies each endpoint
              within a Maintenance Association.  The MPID is used to  identify
              this  endpoint  to other Maintenance Points in the MA.  Each end
              of a link being monitored should have a different MPID.  Must be
              configured to enable CFM on this Interface.

              According  to  the  802.1ag  specification, MPIDs can only range
              between [1,  8191].   However,  extended  mode  (see  other_con
              fig:cfm_extended) supports eight byte MPIDs.

       cfm_flap_count: optional integer
              Counts  the  number  of  cfm fault flapps since boot.  A flap is
              considered to be a change of the cfm_fault value.

       cfm_fault: optional boolean
              Indicates a connectivity fault  triggered  by  an  inability  to
              receive  heartbeats  from  any remote endpoint.  When a fault is
              triggered on Interfaces participating in  bonds,  they  will  be
              disabled.

              Faults  can  be triggered for several reasons.  Most importantly
              they are triggered when no CCMs are received for a period of 3.5
              times  the transmission interval. Faults are also triggered when
              any CCMs indicate that a Remote Maintenance Point is not receiv‐
              ing  CCMs  but able to send them.  Finally, a fault is triggered
              if a CCM is received which indicates  unexpected  configuration.
              Notably,  this  case  arises when a CCM is received which adver‐
              tises the local MPID.

       cfm_fault_status : recv: none
              Indicates a CFM fault was  triggered  due  to  a  lack  of  CCMs
              received on the Interface.

       cfm_fault_status : rdi: none
              Indicates  a  CFM  fault was triggered due to the reception of a
              CCM with the RDI bit flagged.  Endpoints  set  the  RDI  bit  in
              their  CCMs  when  they are not receiving CCMs themselves.  This
              typically indicates a unidirectional connectivity failure.

       cfm_fault_status : maid: none
              Indicates a CFM fault was triggered due to the  reception  of  a
              CCM  with  a  MAID  other  than  the one Open vSwitch uses.  CFM
              broadcasts are tagged with an identification number in  addition
              to the MPID called the MAID.  Open vSwitch only supports receiv‐
              ing CCM broadcasts tagged with the MAID it uses internally.

       cfm_fault_status : loopback: none
              Indicates a CFM fault was triggered due to the  reception  of  a
              CCM  advertising the same MPID configured in the cfm_mpid column
              of this Interface.  This may indicate a loop in the network.

       cfm_fault_status : overflow: none
              Indicates a CFM fault  was  triggered  because  the  CFM  module
              received  CCMs from more remote endpoints than it can keep track
              of.

       cfm_fault_status : override: none
              Indicates a CFM fault was manually triggered by an administrator
              using an ovs-appctl command.

       cfm_fault_status : interval: none
              Indicates  a  CFM  fault was triggered due to the reception of a
              CCM frame having an invalid interval.

       cfm_remote_opstate: optional string, either down or up
              When in extended mode, indicates the operational  state  of  the
              remote   endpoint   as   either  up  or  down.   See  other_con
              fig:cfm_opstate.

       cfm_health: optional integer, in range 0 to 100
              Indicates the health of the interface as  a  percentage  of  CCM
              frames  received over 21 other_config:cfm_intervals.  The health
              of an interface is undefined if it is  communicating  with  more
              than one cfm_remote_mpids.  It reduces if healthy heartbeats are
              not received at the expected rate,  and  gradually  improves  as
              healthy  heartbeats  are  received at the desired rate. Every 21
              other_config:cfm_intervals,  the  health  of  the  interface  is
              refreshed.

              As mentioned above, the faults can be triggered for several rea‐
              sons.  The link health will deteriorate even if  heartbeats  are
              received  but  they  are reported to be unhealthy.  An unhealthy
              heartbeat in this context is a heartbeat for which  either  some
              fault is set or is out of sequence.  The interface health can be
              100 only on receiving healthy heartbeats at the desired rate.

       cfm_remote_mpids: set of integers
              When CFM is properly configured, Open vSwitch will  occasionally
              receive  CCM  broadcasts.   These broadcasts contain the MPID of
              the sending Maintenance Point.  The list  of  MPIDs  from  which
              this  Interface  is  receiving broadcasts from is regularly col‐
              lected and written to this column.

       other_config : cfm_interval: optional string, containing an integer
              The interval, in  milliseconds,  between  transmissions  of  CFM
              heartbeats.   Three  missed heartbeat receptions indicate a con‐
              nectivity fault.

              In standard operation only  intervals  of  3,  10,  100,  1,000,
              10,000,  60,000, or 600,000 ms are supported.  Other values will
              be rounded down to the nearest value on the list.  Extended mode
              (see  other_config:cfm_extended)  supports  any  interval  up to
              65,535 ms.  In either mode, the default is 1000 ms.

              We do not recommend using intervals less than 100 ms.

       other_config : cfm_extended: optional string, either true or false
              When true, the CFM module operates in extended mode. This causes
              it to use a nonstandard destination address to avoid conflicting
              with compliant implementations which may be running concurrently
              on  the  network. Furthermore, extended mode increases the accu‐
              racy of the cfm_interval  configuration  parameter  by  breaking
              wire  compatibility with 802.1ag compliant implementations.  And
              extended mode allows eight byte MPIDs.  Defaults to false.

       other_config : cfm_demand: optional string, either true or false
              When true, and other_config:cfm_extended is true, the CFM module
              operates  in demand mode.  When in demand mode, traffic received
              on the Interface is used to indicate liveness.  CCMs  are  still
              transmitted  and  received.   At  least one CCM must be received
              every 100 * other_config:cfm_interval amount  of  time.   Other‐
              wise,  even  if  traffic are received, the CFM module will raise
              the connectivity fault.

              Demand mode has a couple of caveats:

              ·      To ensure that ovs-vswitchd has enough time to pull  sta‐
                     tistics  from  the datapath, the fault detection interval
                     is set to 3.5 * MAX(other_config:cfm_interval, 500) ms.

              ·      To avoid ambiguity,  demand  mode  disables  itself  when
                     there are multiple remote maintenance points.

              ·      If  the  Interface  is heavily congested, CCMs containing
                     the other_config:cfm_opstate status may be dropped  caus‐
                     ing changes in the operational state to be delayed.  Sim‐
                     ilarly, if CCMs containing the RDI bit are not  received,
                     unidirectional link failures may not be detected.

       other_config : cfm_opstate: optional string, either down or up
              When  down, the CFM module marks all CCMs it generates as opera‐
              tionally down without triggering a fault.   This  allows  remote
              maintenance  points  to  choose  not  to  forward traffic to the
              Interface on which this CFM module is  running.   Currently,  in
              Open vSwitch, the opdown bit of CCMs affects Interfaces partici‐
              pating in bonds, and the bundle OpenFlow action. This setting is
              ignored when CFM is not in extended mode.  Defaults to up.

       other_config : cfm_ccm_vlan: optional string, containing an integer, in
       range 1 to 4,095
              When set, the CFM module will apply a VLAN tag to  all  CCMs  it
              generates  with  the  given  value.  May be the string random in
              which case each CCM will be tagged  with  a  different  randomly
              generated VLAN.

       other_config  : cfm_ccm_pcp: optional string, containing an integer, in
       range 1 to 7
              When set, the CFM module will apply a VLAN tag to  all  CCMs  it
              generates  with  the  given PCP value, the VLAN ID of the tag is
              governed  by  the   value   of   other_config:cfm_ccm_vlan.   If
              other_config:cfm_ccm_vlan is unset, a VLAN ID of zero is used.

     Bonding Configuration:

       other_config : lacp-port-id: optional string, containing an integer, in
       range 1 to 65,535
              The LACP port ID of this Interface.  Port IDs are used  in  LACP
              negotiations  to  identify  individual  ports participating in a
              bond.

       other_config : lacp-port-priority: optional string, containing an inte‐
       ger, in range 1 to 65,535
              The  LACP port priority of this Interface.  In LACP negotiations
              Interfaces with numerically lower priorities are  preferred  for
              aggregation.

       other_config  :  lacp-aggregation-key:  optional  string, containing an
       integer, in range 1 to 65,535
              The LACP aggregation key of  this  Interface.   Interfaces  with
              different aggregation keys may not be active within a given Port
              at the same time.

     Virtual Machine Identifiers:
       These key-value pairs specifically apply to an  interface  that  repre‐
       sents  a  virtual  Ethernet  interface  connected to a virtual machine.
       These key-value pairs should not be present for other types  of  inter‐
       faces.   Keys  whose names end in -uuid have values that uniquely iden‐
       tify the entity in question.  For a Citrix XenServer hypervisor,  these
       values  are  UUIDs in RFC 4122 format.  Other hypervisors may use other
       formats.

       external_ids : attached-mac: optional string
              The MAC address programmed into  the  ``virtual  hardware’’  for
              this  interface,  in  the  form  xx:xx:xx:xx:xx:xx.   For Citrix
              XenServer, this is the value of the MAC field in the VIF  record
              for this interface.

       external_ids : iface-id: optional string
              A  system-unique  identifier  for  the interface.  On XenServer,
              this will commonly be the same as external_ids:xs-vif-uuid.

       external_ids : iface-status: optional string, either active or inactive
              Hypervisors may sometimes have more than one  interface  associ‐
              ated  with  a  given external_ids:iface-id, only one of which is
              actually in use at a given time.  For example, in  some  circum‐
              stances XenServer has both a ``tap’’ and a ``vif’’ interface for
              a single external_ids:iface-id, but only uses one of them  at  a
              time.   A  hypervisor  that  behaves this way must mark the cur‐
              rently in use interface  active  and  the  others  inactive.   A
              hypervisor  that  never  has more than one interface for a given
              external_ids:iface-id may mark that  interface  active  or  omit
              external_ids:iface-status entirely.

              During  VM  migration, a given external_ids:iface-id might tran‐
              siently be marked active on two different hypervisors.  That is,
              active  means  that  this  external_ids:iface-id  is  the active
              instance within a single hypervisor, not  in  a  broader  scope.
              There  is  one exception: some hypervisors support ``migration’’
              from a given hypervisor to itself  (most  often  for  test  pur‐
              poses).   During such a ``migration,’’ two instances of a single
              external_ids:iface-id might both be briefly marked active  on  a
              single hypervisor.

       external_ids : xs-vif-uuid: optional string
              The virtual interface associated with this interface.

       external_ids : xs-network-uuid: optional string
              The virtual network to which this interface is attached.

       external_ids : vm-id: optional string
              The  VM to which this interface belongs. On XenServer, this will
              be the same as external_ids:xs-vm-uuid.

       external_ids : xs-vm-uuid: optional string
              The VM to which this interface belongs.

     VLAN Splinters:
       The ``VLAN splinters’’ feature  increases  Open  vSwitch  compatibility
       with  buggy  network drivers in old versions of Linux that do not prop‐
       erly support VLANs when VLAN devices are not used, at some cost in mem‐
       ory and performance.

       When VLAN splinters are enabled on a particular interface, Open vSwitch
       creates a VLAN device for each in-use VLAN.  For sending traffic tagged
       with  a VLAN on the interface, it substitutes the VLAN device.  Traffic
       received on the VLAN device is treated as if it had  been  received  on
       the interface on the particular VLAN.

       VLAN splinters consider a VLAN to be in use if:

              ·      The VLAN is the tag value in any Port record.

              ·      The  VLAN  is listed within the trunks column of the Port
                     record of  an  interface  on  which  VLAN  splinters  are
                     enabled.   An  empty trunks does not influence the in-use
                     VLANs: creating 4,096 VLAN devices is impractical because
                     it will exceed the current 1,024 port per datapath limit.

              ·      An OpenFlow flow within any bridge matches the VLAN.

       The  same  set of in-use VLANs applies to every interface on which VLAN
       splinters are enabled.  That is, the set is not chosen  separately  for
       each interface but selected once as the union of all in-use VLANs based
       on the rules above.

       It does not make sense to enable VLAN splinters on an interface for  an
       access port, or on an interface that is not a physical port.

       VLAN  splinters  are  deprecated.   When  broken  device drivers are no
       longer in widespread use, we will delete this feature.

       other_config : enable-vlan-splinters: optional string, either  true  or
       false
              Set  to  true  to  enable  VLAN  splinters  on  this  interface.
              Defaults to false.

              VLAN splinters increase kernel and userspace memory overhead, so
              do not use them unless they are needed.

              VLAN  splinters  do  not support 802.1p priority tags.  Received
              priorities will appear to be 0, regardless of their actual  val‐
              ues,  and priorities on transmitted packets will also be cleared
              to 0.

     Auto Attach Configuration:
       Auto Attach configuration for a particular interface.

       lldp : enable: optional string, either true or false
              True to enable LLDP on this Interface.  If not  specified,  LLDP
              will be disabled by default.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Flow_Table TABLE
       Configuration for a particular OpenFlow table.

   Summary:
       name                          optional string
       Eviction Policy:
         flow_limit                  optional integer, at least 0
         overflow_policy             optional string, either refuse or evict
         groups                      set of strings
       Classifier Optimization:
         prefixes                    set of up to 3 strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: optional string
              The table’s name.  Set this column to change the name that  con‐
              trollers  will  receive when they request table statistics, e.g.
              ovs-ofctl dump-tables.  The name does not affect  switch  behav‐
              ior.

     Eviction Policy:
       Open  vSwitch  supports  limiting  the  number  of  flows  that  may be
       installed in a flow table, via the flow_limit column.   When  adding  a
       flow would exceed this limit, by default Open vSwitch reports an error,
       but there are two ways to configure  Open  vSwitch  to  instead  delete
       (``evict’’) a flow to make room for the new one:

              ·      Set the overflow_policy column to evict.

              ·      Send  an  OpenFlow  1.4+  ``table mod request’’ to enable
                     eviction for the flow table (e.g. ovs-ofctl -O OpenFlow14
                     mod-table  br0 0 evict to enable eviction on flow table 0
                     of bridge br0).

       When a flow must be evicted due to overflow, the flow to evict is  cho‐
       sen  through  an  approximation of the following algorithm.  This algo‐
       rithm is used regardless of how eviction was enabled:

              1.
                Divide the flows in the table into groups based on the  values
                of  the fields or subfields specified in the groups column, so
                that all of the flows in a given group have  the  same  values
                for  those  fields.  If a flow does not specify a given field,
                that field’s value is treated as 0.  If groups is empty,  then
                all  of  the  flows  in the flow table are treated as a single
                group.

              2.
                Consider the flows in the largest group, that  is,  the  group
                that  contains  the  greatest number of flows.  If two or more
                groups all have the same largest number of flows, consider the
                flows in all of those groups.

              3.
                If  the  flows  under  consideration have different importance
                values, eliminate from consideration any  flows  except  those
                with the lowest importance.  (``Importance,’’ a 16-bit integer
                value attached to each flow, was introduced in  OpenFlow  1.4.
                Flows  inserted with older versions of OpenFlow always have an
                importance of 0.)

              4.
                Among the flows under  consideration,  choose  the  flow  that
                expires soonest for eviction.

       The  eviction process only considers flows that have an idle timeout or
       a hard timeout.  That  is,  eviction  never  deletes  permanent  flows.
       (Permanent flows do count against flow_limit.)

       flow_limit: optional integer, at least 0
              If  set, limits the number of flows that may be added to the ta‐
              ble.  Open vSwitch may limit the number of flows in a table  for
              other  reasons, e.g. due to hardware limitations or for resource
              availability or performance reasons.

       overflow_policy: optional string, either refuse or evict
              Controls the switch’s behavior when an OpenFlow flow table modi‐
              fication  request  would add flows in excess of flow_limit.  The
              supported values are:

              refuse Refuse to add the  flow  or  flows.   This  is  also  the
                     default policy when overflow_policy is unset.

              evict  Delete a flow chosen according to the algorithm described
                     above.

       groups: set of strings
              When overflow_policy is evict, this controls how flows are  cho‐
              sen  for  eviction  when  the  flow table would otherwise exceed
              flow_limit flows.  Its value is a set  of  NXM  fields  or  sub-
              fields,  each  of  which  takes  one  of  the  forms  field[] or
              field[start..end],   e.g.    NXM_OF_IN_PORT[].     Please    see
              nicira-ext.h for a complete list of NXM field names.

              Open  vSwitch  ignores  any  invalid or unknown field specifica‐
              tions.

              When eviction is not enabled, via overflow_policy or an OpenFlow
              1.4+ ``table mod,’’ this column has no effect.

     Classifier Optimization:

       prefixes: set of up to 3 strings
              This  string  set  specifies  which  fields  should  be used for
              address prefix tracking.  Prefix tracking allows the  classifier
              to  skip rules with longer than necessary prefixes, resulting in
              better wildcarding for datapath flows.

              Prefix tracking may be beneficial when  a  flow  table  contains
              matches on IP address fields with different prefix lengths.  For
              example, when a flow table contains IP address matches  on  both
              full  addresses  and  proper  prefixes, the full address matches
              will typically cause the datapath flow to un-wildcard the  whole
              address  field  (depending  on  flow entry priorities).  In this
              case each packet with a different address  gets  handed  to  the
              userspace  for  flow  processing  and generates its own datapath
              flow.  With prefix tracking enabled for  the  address  field  in
              question  packets with addresses matching shorter prefixes would
              generate datapath flows where the irrelevant  address  bits  are
              wildcarded,  allowing  the  same datapath flow to handle all the
              packets within the  prefix  in  question.   In  this  case  many
              userspace upcalls can be avoided and the overall performance can
              be better.

              This is a performance optimization only, so packets will receive
              the same treatment with or without prefix tracking.

              The  supported  fields  are:  tun_id,  tun_src, tun_dst, nw_src,
              nw_dst (or aliases ip_src and ip_dst), ipv6_src,  and  ipv6_dst.
              (Using this feature for tun_id would only make sense if the tun‐
              nel IDs have prefix structure similar to IP addresses.)

              By default, the prefixes=ip_dst,ip_src are used on each flow ta‐
              ble.   This instructs the flow classifier to track the IP desti‐
              nation and source addresses used by the rules in  this  specific
              flow table.

              The  keyword  none  is recognized as an explicit override of the
              default values, causing no prefix fields to be tracked.

              To set the prefix fields, the flow table record needs to exist:

              ovs-vsctl set Bridge br0 flow_tables:0=@N1  --  --id=@N1  create
              Flow_Table name=table0
                     Creates a flow table record for the OpenFlow table number
                     0.

              ovs-vsctl set Flow_Table table0 prefixes=ip_dst,ip_src
                     Enables prefix tracking for  IP  source  and  destination
                     address fields.

              There  is a maximum number of fields that can be enabled for any
              one flow table.  Currently this limit is 3.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

QoS TABLE
       Quality  of  Service  (QoS) configuration for each Port that references
       it.

   Summary:
       type                          string
       queues                        map of integer-Queue pairs, key in  range
                                     0 to 4,294,967,295
       Configuration for linux-htb and linux-hfsc:
         other_config : max-rate     optional string, containing an integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       type: string
              The  type  of  QoS to implement. The currently defined types are
              listed below:

              linux-htb
                     Linux ``hierarchy token  bucket’’  classifier.   See  tc-
                     htb(8)  (also  at  http://linux.die.net/man/8/tc-htb) and
                     the HTB  manual  (http://luxik.cdi.cz/~devik/qos/htb/man
                     ual/userg.htm)  for  information  on  how this classifier
                     works and how to configure it.

              linux-hfsc
                     Linux "Hierarchical Fair Service Curve" classifier.   See
                     http://linux-ip.net/articles/hfsc.en/  for information on
                     how this classifier works.

              linux-sfq
                     Linux ``Stochastic Fairness  Queueing’’  classifier.  See
                     tc-sfq(8) (also at http://linux.die.net/man/8/tc-sfq) for
                     information on how this classifier works.

              linux-codel
                     Linux ``Controlled Delay’’  classifier.  See  tc-codel(8)
                     (also                                                  at
                     http://man7.org/linux/man-pages/man8/tc-codel.8.html) for
                     information on how this classifier works.

              linux-fq_codel
                     Linux  ``Fair Queuing with Controlled Delay’’ classifier.
                     See           tc-fq_codel(8)           (also           at
                     http://man7.org/linux/man-pages/man8/tc-fq_codel.8.html)
                     for information on how this classifier works.

       queues: map of integer-Queue pairs, key in range 0 to 4,294,967,295
              A map from queue numbers to Queue records.  The supported  range
              of queue numbers depend on type.  The queue numbers are the same
              as the queue_id used in OpenFlow  in  struct  ofp_action_enqueue
              and other structures.

              Queue 0 is the ``default queue.’’  It is used by OpenFlow output
              actions when no specific queue has been set.  When no configura‐
              tion  for  queue 0 is present, it is automatically configured as
              if a Queue record with empty dscp and other_config  columns  had
              been  specified.   (Before version 1.6, Open vSwitch would leave
              queue 0 unconfigured in this case.   With  some  queuing  disci‐
              plines,  this  dropped  all  packets  destined  for  the default
              queue.)

     Configuration for linux-htb and linux-hfsc:
       The linux-htb and linux-hfsc classes support  the  following  key-value
       pair:

       other_config : max-rate: optional string, containing an integer
              Maximum  rate shared by all queued traffic, in bit/s.  Optional.
              If not specified, for physical interfaces, the  default  is  the
              link  rate.   For other interfaces or if the link rate cannot be
              determined, the default is currently 100 Mbps.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Queue TABLE
       A configuration for a port output queue, used in configuring Quality of
       Service (QoS) features.  May be referenced by queues column in QoS  ta‐
       ble.

   Summary:
       dscp                          optional integer, in range 0 to 63
       Configuration for linux-htb QoS:
         other_config : min-rate     optional  string,  containing an integer,
                                     at least 1
         other_config : max-rate     optional string, containing  an  integer,
                                     at least 1
         other_config : burst        optional  string,  containing an integer,
                                     at least 1
         other_config : priority     optional string, containing  an  integer,
                                     in range 0 to 4,294,967,295
       Configuration for linux-hfsc QoS:
         other_config : min-rate     optional  string,  containing an integer,
                                     at least 1
         other_config : max-rate     optional string, containing  an  integer,
                                     at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       dscp: optional integer, in range 0 to 63
              If  set, Open vSwitch will mark all traffic egressing this Queue
              with the given DSCP bits.  Traffic egressing the  default  Queue
              is only marked if it was explicitly selected as the Queue at the
              time the packet was output.  If unset, the DSCP bits of  traffic
              egressing this Queue will remain unchanged.

     Configuration for linux-htb QoS:
       QoS  type linux-htb may use queue_ids less than 61440.  It has the fol‐
       lowing key-value pairs defined.

       other_config : min-rate: optional string,  containing  an  integer,  at
       least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config  :  max-rate:  optional  string, containing an integer, at
       least 1
              Maximum allowed bandwidth, in bit/s.  Optional.   If  specified,
              the  queue’s  rate  will  not be allowed to exceed the specified
              value, even if excess bandwidth is available.   If  unspecified,
              defaults to no limit.

       other_config  : burst: optional string, containing an integer, at least
       1
              Burst size, in bits.  This is the maximum amount of  ``credits’’
              that  a  queue  can  accumulate  while  it  is  idle.  Optional.
              Details of the linux-htb implementation require a minimum  burst
              size, so a too-small burst will be silently ignored.

       other_config  :  priority:  optional  string, containing an integer, in
       range 0 to 4,294,967,295
              A queue with a smaller priority  will  receive  all  the  excess
              bandwidth  that  it  can  use before a queue with a larger value
              receives any.  Specific priority values  are  unimportant;  only
              relative ordering matters.  Defaults to 0 if unspecified.

     Configuration for linux-hfsc QoS:
       QoS type linux-hfsc may use queue_ids less than 61440.  It has the fol‐
       lowing key-value pairs defined.

       other_config : min-rate: optional string,  containing  an  integer,  at
       least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config  :  max-rate:  optional  string, containing an integer, at
       least 1
              Maximum allowed bandwidth, in bit/s.  Optional.   If  specified,
              the  queue’s  rate  will  not be allowed to exceed the specified
              value, even if excess bandwidth is available.   If  unspecified,
              defaults to no limit.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Mirror TABLE
       A port mirror within a Bridge.

       A port mirror configures a bridge to send selected  frames  to  special
       ``mirrored’’  ports, in addition to their normal destinations.  Mirror‐
       ing traffic may also be referred to as SPAN or RSPAN, depending on  how
       the mirrored traffic is sent.

       When  a  packet  enters an Open vSwitch bridge, it becomes eligible for
       mirroring based on its ingress port and VLAN.  As  the  packet  travels
       through  the  flow tables, each time it is output to a port, it becomes
       eligible for mirroring based on the egress  port  and  VLAN.   In  Open
       vSwitch  2.5  and  later,  mirroring  occurs  just after a packet first
       becomes eligible, using the packet as it exists at that point; in  Open
       vSwitch  2.4 and earlier, mirroring occurs only after a packet has tra‐
       versed all the flow tables, using the original packet as it entered the
       bridge.   This makes a difference only when the flow table modifies the
       packet: in Open vSwitch 2.4, the modifications  are  never  visible  to
       mirrors,  whereas  in  Open  vSwitch  2.5  and later modifications made
       before the first output that makes it eligible for mirroring to a  par‐
       ticular destination are visible.

       A packet that enters an Open vSwitch bridge is mirrored to a particular
       destination only once, even if it is  eligible  for  multiple  reasons.
       For  example,  a  packet  would be mirrored to a particular output_port
       only once, even if it  is  selected  for  mirroring  to  that  port  by
       select_dst_port  and  select_src_port  in  the same or different Mirror
       records.

   Summary:
       name                          string
       Selecting Packets for Mirroring:
         select_all                  boolean
         select_dst_port             set of weak reference to Ports
         select_src_port             set of weak reference to Ports
         select_vlan                 set of up to 4,096 integers, in  range  0
                                     to 4,095
       Mirroring Destination Configuration:
         output_port                 optional weak reference to Port
         output_vlan                 optional integer, in range 1 to 4,095
       Statistics: Mirror counters:
         statistics : tx_packets     optional integer
         statistics : tx_bytes       optional integer
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string
              Arbitrary identifier for the Mirror.

     Selecting Packets for Mirroring:
       To  be  selected  for mirroring, a given packet must enter or leave the
       bridge through a selected port and it  must  also  be  in  one  of  the
       selected VLANs.

       select_all: boolean
              If  true,  every  packet  arriving  or  departing on any port is
              selected for mirroring.

       select_dst_port: set of weak reference to Ports
              Ports on which departing packets are selected for mirroring.

       select_src_port: set of weak reference to Ports
              Ports on which arriving packets are selected for mirroring.

       select_vlan: set of up to 4,096 integers, in range 0 to 4,095
              VLANs on which packets are selected for mirroring.  An empty set
              selects packets on all VLANs.

     Mirroring Destination Configuration:
       These  columns  are  mutually  exclusive.   Exactly one of them must be
       nonempty.

       output_port: optional weak reference to Port
              Output port for selected packets, if nonempty.

              Specifying a port for mirror output reserves  that  port  exclu‐
              sively  for  mirroring.  No frames other than those selected for
              mirroring via this column will be forwarded to the port, and any
              frames received on the port will be discarded.

              The  output  port  may  be  any  kind  of port supported by Open
              vSwitch.  It may be, for example,  a  physical  port  (sometimes
              called SPAN) or a GRE tunnel.

       output_vlan: optional integer, in range 1 to 4,095
              Output VLAN for selected packets, if nonempty.

              The frames will be sent out all ports that trunk output_vlan, as
              well as any ports with implicit VLAN output_vlan.  When  a  mir‐
              rored  frame is sent out a trunk port, the frame’s VLAN tag will
              be set to output_vlan, replacing any existing tag;  when  it  is
              sent  out  an  implicit VLAN port, the frame will not be tagged.
              This type of mirroring is sometimes called RSPAN.

              See  the  documentation  for  other_config:forward-bpdu  in  the
              Interface  table  for  a list of destination MAC addresses which
              will not be mirrored to a VLAN to avoid confusing switches  that
              interpret the protocols that they represent.

              Please note: Mirroring to a VLAN can disrupt a network that con‐
              tains unmanaged switches.  Consider an unmanaged physical switch
              with  two  ports:  port 1, connected to an end host, and port 2,
              connected to an Open vSwitch configured to mirror received pack‐
              ets  into VLAN 123 on port 2.  Suppose that the end host sends a
              packet on port 1 that the physical switch forwards  to  port  2.
              The  Open  vSwitch  forwards  this packet to its destination and
              then reflects it back on port 2 in  VLAN  123.   This  reflected
              packet  causes  the unmanaged physical switch to replace the MAC
              learning table entry, which correctly pointed to  port  1,  with
              one  that incorrectly points to port 2.  Afterward, the physical
              switch will direct packets destined for the end host to the Open
              vSwitch  on  port  2, instead of to the end host on port 1, dis‐
              rupting connectivity.  If mirroring to a VLAN is desired in this
              scenario,  then the physical switch must be replaced by one that
              learns Ethernet addresses on a  per-VLAN  basis.   In  addition,
              learning  should  be  disabled  on  the VLAN containing mirrored
              traffic. If this is not done  then  intermediate  switches  will
              learn  the  MAC address of each end host from the mirrored traf‐
              fic.  If packets being sent to that end host are also  mirrored,
              then  they will be dropped since the switch will attempt to send
              them out the input port. Disabling learning for  the  VLAN  will
              cause the switch to correctly send the packet out all ports con‐
              figured for that VLAN.  If Open vSwitch  is  being  used  as  an
              intermediate switch, learning can be disabled by adding the mir‐
              rored VLAN to flood_vlans in the  appropriate  Bridge  table  or
              tables.

              Mirroring  to a GRE tunnel has fewer caveats than mirroring to a
              VLAN and should generally be preferred.

     Statistics: Mirror counters:
       Key-value pairs that report mirror statistics.  The  update  period  is
       controlled  by  other_config:stats-update-interval  in the Open_vSwitch
       table.

       statistics : tx_packets: optional integer
              Number of packets transmitted through this mirror.

       statistics : tx_bytes: optional integer
              Number of bytes transmitted through this mirror.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

Controller TABLE
       An OpenFlow controller.

       Open vSwitch supports two kinds of OpenFlow controllers:

              Primary controllers
                     This is the kind of controller envisioned by the OpenFlow
                     1.0 specification.  Usually, a primary controller  imple‐
                     ments  a  network policy by taking charge of the switch’s
                     flow table.

                     Open vSwitch initiates and maintains  persistent  connec‐
                     tions  to  primary  controllers,  retrying the connection
                     each time it fails or drops.  The fail_mode column in the
                     Bridge table applies to primary controllers.

                     Open  vSwitch permits a bridge to have any number of pri‐
                     mary controllers.  When multiple controllers are  config‐
                     ured,  Open  vSwitch  connects  to all of them simultane‐
                     ously.  Because OpenFlow 1.0 does not specify how  multi‐
                     ple  controllers  coordinate in interacting with a single
                     switch, more than one primary controller should be speci‐
                     fied  only  if the controllers are themselves designed to
                     coordinate with each other.  (The Nicira-defined NXT_ROLE
                     OpenFlow vendor extension may be useful for this.)

              Service controllers
                     These   kinds  of  OpenFlow  controller  connections  are
                     intended for occasional support and maintenance use, e.g.
                     with  ovs-ofctl.   Usually  a service controller connects
                     only briefly to inspect or  modify  some  of  a  switch’s
                     state.

                     Open  vSwitch  listens for incoming connections from ser‐
                     vice controllers.  The service controllers initiate  and,
                     if  necessary,  maintain  the connections from their end.
                     The fail_mode column in the Bridge table does  not  apply
                     to service controllers.

                     Open  vSwitch  supports configuring any number of service
                     controllers.

       The target determines the type of controller.

   Summary:
       Core Features:
         target                      string
         connection_mode             optional  string,   either   in-band   or
                                     out-of-band
       Controller Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Asynchronous Messages:
         enable_async_messages       optional boolean
         Controller Rate Limiting:
            controller_rate_limit    optional integer, at least 100
            controller_burst_limit   optional integer, at least 25
            Controller Rate Limiting Statistics:
              status : packet-in-TYPE-bypassed
                                     optional  string,  containing an integer,
                                     at least 0
              status : packet-in-TYPE-queued
                                     optional string, containing  an  integer,
                                     at least 0
              status : packet-in-TYPE-dropped
                                     optional  string,  containing an integer,
                                     at least 0
              status : packet-in-TYPE-backlog
                                     optional string, containing  an  integer,
                                     at least 0
       Additional In-Band Configuration:
         local_ip                    optional string
         local_netmask               optional string
         local_gateway               optional string
       Controller Status:
         is_connected                boolean
         role                        optional  string, one of slave, other, or
                                     master
         status : last_error         optional string
         status : state              optional string,  one  of  ACTIVE,  VOID,
                                     CONNECTING, IDLE, or BACKOFF
         status : sec_since_connect  optional  string,  containing an integer,
                                     at least 0
         status : sec_since_disconnect
                                     optional string, containing  an  integer,
                                     at least 1
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       target: string
              Connection method for controller.

              The  following  connection  methods  are currently supported for
              primary controllers:

              ssl:ip[:port]
                     The specified SSL port on the host at the given ip, which
                     must be expressed as an IP address (not a DNS name).  The
                     ssl column in the Open_vSwitch  table  must  point  to  a
                     valid SSL configuration when this form is used.

                     If port is not specified, it defaults to 6653.

                     SSL  support  is  an  optional feature that is not always
                     built as part of Open vSwitch.

              tcp:ip[:port]
                     The specified TCP port on the host at the given ip, which
                     must  be  expressed  as  an  IP address (not a DNS name),
                     where ip can be IPv4 or IPv6 address.  If ip is  an  IPv6
                     address, wrap it in square brackets, e.g. tcp:[::1]:6653.

                     If port is not specified, it defaults to 6653.

              The  following  connection  methods  are currently supported for
              service controllers:

              pssl:[port][:ip]
                     Listens for SSL connections on the  specified  TCP  port.
                     If  ip,  which  must be expressed as an IP address (not a
                     DNS name), is specified, then connections are  restricted
                     to  the specified local IP address (either IPv4 or IPv6).
                     If ip is an IPv6 address, wrap  it  in  square  brackets,
                     e.g. pssl:6653:[::1].

                     If  port is not specified, it defaults to 6653.  If ip is
                     not specified then it listens only on IPv4 (but not IPv6)
                     addresses.  The ssl column in the Open_vSwitch table must
                     point to a valid SSL  configuration  when  this  form  is
                     used.

                     If port is not specified, it currently to 6653.

                     SSL  support  is  an  optional feature that is not always
                     built as part of Open vSwitch.

              ptcp:[port][:ip]
                     Listens for connections on the specified  TCP  port.   If
                     ip,  which  must be expressed as an IP address (not a DNS
                     name), is specified, then connections are  restricted  to
                     the specified local IP address (either IPv4 or IPv6).  If
                     ip is an IPv6 address, wrap it in square  brackets,  e.g.
                     ptcp:6653:[::1].  If  ip is not specified then it listens
                     only on IPv4 addresses.

                     If port is not specified, it defaults to 6653.

              When multiple controllers are configured for  a  single  bridge,
              the target values must be unique.  Duplicate target values yield
              unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If it is specified, this setting must be one  of  the  following
              strings  that  describes how Open vSwitch contacts this OpenFlow
              controller over the network:

              in-band
                     In this mode, this controller’s OpenFlow traffic  travels
                     over  the  bridge  associated  with the controller.  With
                     this setting, Open vSwitch allows traffic to and from the
                     controller  regardless  of  the  contents of the OpenFlow
                     flow table.  (Otherwise, Open vSwitch would never be able
                     to  connect  to the controller, because it did not have a
                     flow to enable it.)  This is the most  common  connection
                     mode because it is not necessary to maintain two indepen‐
                     dent networks.

              out-of-band
                     In this mode, OpenFlow traffic  uses  a  control  network
                     separate from the bridge associated with this controller,
                     that is, the bridge does not use any of its  own  network
                     devices  to communicate with the controller.  The control
                     network must be configured separately,  before  or  after
                     ovs-vswitchd is started.

              If not specified, the default is implementation-specific.

     Controller Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum  number  of  milliseconds  to  wait  between  connection
              attempts.  Default is implementation-specific.

       inactivity_probe: optional integer
              Maximum number of milliseconds of idle  time  on  connection  to
              controller  before sending an inactivity probe message.  If Open
              vSwitch does not communicate with the controller for the  speci‐
              fied  number of seconds, it will send a probe.  If a response is
              not received for  the  same  additional  amount  of  time,  Open
              vSwitch  assumes  the connection has been broken and attempts to
              reconnect.  Default is implementation-specific.  A  value  of  0
              disables inactivity probes.

     Asynchronous Messages:
       OpenFlow  switches send certain messages to controllers spontanenously,
       that is, not in response to any request  from  the  controller.   These
       messages  are  called  ``asynchronous  messages.’’  These columns allow
       asynchronous messages to be limited or disabled to ensure the best  use
       of network resources.

       enable_async_messages: optional boolean
              The  OpenFlow  protocol enables asynchronous messages at time of
              connection establishment, which  means  that  a  controller  can
              receive asynchronous messages, potentially many of them, even if
              it turns them off immediately after connecting.  Set this column
              to false to change Open vSwitch behavior to disable, by default,
              all  asynchronous  messages.   The  controller   can   use   the
              NXT_SET_ASYNC_CONFIG Nicira extension to OpenFlow to turn on any
              messages that it does want to receive, if any.

     Controller Rate Limiting:
       A switch can forward packets to a controller over the  OpenFlow  proto‐
       col.   Forwarding  packets  this way at too high a rate can overwhelm a
       controller, frustrate use of the OpenFlow  connection  for  other  pur‐
       poses,  increase  the  latency  of  flow setup, and use an unreasonable
       amount of bandwidth.  Therefore, Open  vSwitch  supports  limiting  the
       rate of packet forwarding to a controller.

       There  are  two  main  reasons in OpenFlow for a packet to be sent to a
       controller: either the packet ``misses’’ in the flow  table,  that  is,
       there  is  no  matching  flow,  or a flow table action says to send the
       packet to the controller.  Open vSwitch limits the rate of each kind of
       packet  separately  at the configured rate.  Therefore, the actual rate
       that packets are sent to the controller can be up to twice the  config‐
       ured rate, when packets are sent for both reasons.

       This feature is specific to forwarding packets over an OpenFlow connec‐
       tion.  It is not general-purpose QoS.  See the QoS table for quality of
       service configuration, and ingress_policing_rate in the Interface table
       for ingress policing configuration.

       controller_rate_limit: optional integer, at least 100
              The maximum rate at which the switch will forward packets to the
              OpenFlow  controller,  in  packets  per  second.  If no value is
              specified, rate limiting is disabled.

       controller_burst_limit: optional integer, at least 25
              When a high rate triggers  rate-limiting,  Open  vSwitch  queues
              packets  to  the  controller for each port and transmits them to
              the controller at the configured rate.  This  value  limits  the
              number  of  queued  packets.  Ports on a bridge share the packet
              queue fairly.

              This value has no effect unless controller_rate_limit is config‐
              ured.   The  current default when this value is not specified is
              one-quarter of controller_rate_limit, meaning that  queuing  can
              delay forwarding a packet to the controller by up to 250 ms.

     Controller Rate Limiting Statistics:
       These  values  report  the  effects of rate limiting.  Their values are
       relative to establishment of the most recent  OpenFlow  connection,  or
       since  rate  limiting  was  enabled,  whichever happened more recently.
       Each consists of two values, one with TYPE replaced by  miss  for  rate
       limiting  flow table misses, and the other with TYPE replaced by action
       for rate limiting packets sent by OpenFlow actions.

       These statistics are reported only when  controller  rate  limiting  is
       enabled.

       status  : packet-in-TYPE-bypassed: optional string, containing an inte‐
       ger, at least 0
              Number of packets sent directly to the controller, without queu‐
              ing, because the rate did not exceed the configured maximum.

       status : packet-in-TYPE-queued: optional string, containing an integer,
       at least 0
              Number of packets added to the queue to send later.

       status : packet-in-TYPE-dropped: optional string, containing  an  inte‐
       ger, at least 0
              Number of packets added to the queue that were later dropped due
              to overflow.  This value is less than or equal to status:packet-
              in-TYPE-queued.

       status  :  packet-in-TYPE-backlog: optional string, containing an inte‐
       ger, at least 0
              Number  of  packets  currently  queued.   The  other  statistics
              increase  monotonically,  but  this one fluctuates between 0 and
              the controller_burst_limit as conditions change.

     Additional In-Band Configuration:
       These values are considered only in in-band control mode  (see  connec
       tion_mode).

       When  multiple  controllers  are  configured  on a single bridge, there
       should be only one set of unique values in these columns.  If different
       values  are  set for these columns in different controllers, the effect
       is unspecified.

       local_ip: optional string
              The  IP  address  to  configure  on   the   local   port,   e.g.
              192.168.0.123.   If  this value is unset, then local_netmask and
              local_gateway are ignored.

       local_netmask: optional string
              The  IP  netmask  to  configure  on   the   local   port,   e.g.
              255.255.255.0.  If local_ip is set but this value is unset, then
              the default is chosen based on whether the IP address  is  class
              A, B, or C.

       local_gateway: optional string
              The IP address of the gateway to configure on the local port, as
              a string, e.g. 192.168.0.1.  Leave this  column  unset  if  this
              network has no gateway.

     Controller Status:

       is_connected: boolean
              true if currently connected to this controller, false otherwise.

       role: optional string, one of slave, other, or master
              The  level  of  authority  this controller has on the associated
              bridge. Possible values are:

              other  Allows the controller access to all OpenFlow features.

              master Equivalent to other, except that there may be at most one
                     master  controller  at a time.  When a controller config‐
                     ures itself as master, any existing master is demoted  to
                     the slave role.

              slave  Allows  the  controller read-only access to OpenFlow fea‐
                     tures.   Attempts  to  modify  the  flow  table  will  be
                     rejected with an error.  Slave controllers do not receive
                     OFPT_PACKET_IN or OFPT_FLOW_REMOVED messages, but they do
                     receive OFPT_PORT_STATUS messages.

       status : last_error: optional string
              A human-readable description of the last error on the connection
              to the controller; i.e. strerror(errno).  This  key  will  exist
              only if an error has occurred.

       status : state: optional string, one of ACTIVE, VOID, CONNECTING, IDLE,
       or BACKOFF
              The state of the connection to the controller:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle.  Waiting for response to keep-alive.

              These values may change in the future.  They are  provided  only
              for human consumption.

       status  : sec_since_connect: optional string, containing an integer, at
       least 0
              The amount of time since this controller last successfully  con‐
              nected to the switch (in seconds).  Value is empty if controller
              has never successfully connected.

       status : sec_since_disconnect: optional string, containing an  integer,
       at least 1
              The  amount of time since this controller last disconnected from
              the switch (in seconds). Value is empty if controller has  never
              disconnected.

     Connection Parameters:
       Additional  configuration  for  a connection between the controller and
       the Open vSwitch.

       other_config : dscp: optional string, containing an integer
              The Differentiated Service Code Point (DSCP) is specified  using
              6 bits in the Type of Service (TOS) field in the IP header. DSCP
              provides a mechanism to classify the network traffic and provide
              Quality  of Service (QoS) on IP networks.  The DSCP value speci‐
              fied here is used when establishing the connection  between  the
              controller  and  the  Open vSwitch.  If no value is specified, a
              default value of 48 is chosen.  Valid DSCP values must be in the
              range 0 to 63.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

Manager TABLE
       Configuration for a database connection to  an  Open  vSwitch  database
       (OVSDB) client.

       This   table   primarily   configures   the   Open   vSwitch   database
       (ovsdb-server), not the Open vSwitch switch (ovs-vswitchd).  The switch
       does  read the table to determine what connections should be treated as
       in-band.

       The Open vSwitch database server can initiate and maintain active  con‐
       nections  to  remote  clients.  It can also listen for database connec‐
       tions.

   Summary:
       Core Features:
         target                      string (must be unique within table)
         connection_mode             optional  string,   either   in-band   or
                                     out-of-band
       Client Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Status:
         is_connected                boolean
         status : last_error         optional string
         status : state              optional  string,  one  of  ACTIVE, VOID,
                                     CONNECTING, IDLE, or BACKOFF
         status : sec_since_connect  optional string, containing  an  integer,
                                     at least 0
         status : sec_since_disconnect
                                     optional  string,  containing an integer,
                                     at least 0
         status : locks_held         optional string
         status : locks_waiting      optional string
         status : locks_lost         optional string
         status : n_connections      optional string, containing  an  integer,
                                     at least 2
         status : bound_port         optional string, containing an integer
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       target: string (must be unique within table)
              Connection method for managers.

              The following connection methods are currently supported:

              ssl:ip[:port]
                     The specified SSL port on the host at the given ip, which
                     must be expressed as an IP address (not a DNS name).  The
                     ssl  column  in  the  Open_vSwitch  table must point to a
                     valid SSL configuration when this form is used.

                     If port is not specified, it defaults to 6640.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              tcp:ip[:port]
                     The specified TCP port on the host at the given ip, which
                     must be expressed as an IP  address  (not  a  DNS  name),
                     where  ip  can be IPv4 or IPv6 address.  If ip is an IPv6
                     address, wrap it in square brackets, e.g. tcp:[::1]:6640.

                     If port is not specified, it defaults to 6640.

              pssl:[port][:ip]
                     Listens for SSL connections on the  specified  TCP  port.
                     Specify  0  for  port  to  have  the kernel automatically
                     choose an available port.  If ip, which must be expressed
                     as  an  IP  address  (not a DNS name), is specified, then
                     connections are restricted  to  the  specified  local  IP
                     address  (either IPv4 or IPv6 address).  If ip is an IPv6
                     address, wrap in square brackets,  e.g.  pssl:6640:[::1].
                     If  ip is not specified then it listens only on IPv4 (but
                     not IPv6) addresses.  The ssl column in the  Open_vSwitch
                     table  must  point to a valid SSL configuration when this
                     form is used.

                     If port is not specified, it defaults to 6640.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              ptcp:[port][:ip]
                     Listens for connections on the specified TCP port.  Spec‐
                     ify 0 for port to have the kernel automatically choose an
                     available  port.  If ip, which must be expressed as an IP
                     address (not a DNS name), is specified, then  connections
                     are  restricted to the specified local IP address (either
                     IPv4 or IPv6 address).  If ip is an IPv6 address, wrap it
                     in  square  brackets, e.g. ptcp:6640:[::1].  If ip is not
                     specified then it listens only on IPv4 addresses.

                     If port is not specified, it defaults to 6640.

              When multiple managers are configured, the target values must be
              unique.  Duplicate target values yield unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If  it  is  specified, this setting must be one of the following
              strings that describes how  Open  vSwitch  contacts  this  OVSDB
              client over the network:

              in-band
                     In  this  mode,  this connection’s traffic travels over a
                     bridge managed by Open vSwitch.  With this setting,  Open
                     vSwitch  allows traffic to and from the client regardless
                     of the contents of the OpenFlow flow table.   (Otherwise,
                     Open  vSwitch  would  never  be  able  to  connect to the
                     client, because it did not have a  flow  to  enable  it.)
                     This is the most common connection mode because it is not
                     necessary to maintain two independent networks.

              out-of-band
                     In this mode, the client’s traffic uses a control network
                     separate from that managed by Open vSwitch, that is, Open
                     vSwitch does not use any of its own  network  devices  to
                     communicate with the client.  The control network must be
                     configured separately, before or  after  ovs-vswitchd  is
                     started.

              If not specified, the default is implementation-specific.

     Client Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum  number  of  milliseconds  to  wait  between  connection
              attempts.  Default is implementation-specific.

       inactivity_probe: optional integer
              Maximum number of milliseconds of idle time on connection to the
              client  before  sending  an  inactivity  probe message.  If Open
              vSwitch does not communicate with the client for  the  specified
              number  of  seconds, it will send a probe.  If a response is not
              received for the same additional amount of  time,  Open  vSwitch
              assumes  the  connection  has been broken and attempts to recon‐
              nect.  Default is implementation-specific.  A value  of  0  dis‐
              ables inactivity probes.

     Status:

       is_connected: boolean
              true if currently connected to this manager, false otherwise.

       status : last_error: optional string
              A human-readable description of the last error on the connection
              to the manager; i.e. strerror(errno).  This key will exist  only
              if an error has occurred.

       status : state: optional string, one of ACTIVE, VOID, CONNECTING, IDLE,
       or BACKOFF
              The state of the connection to the manager:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle.  Waiting for response to keep-alive.

              These values may change in the future.  They are  provided  only
              for human consumption.

       status  : sec_since_connect: optional string, containing an integer, at
       least 0
              The amount of time since this  manager  last  successfully  con‐
              nected  to  the database (in seconds). Value is empty if manager
              has never successfully connected.

       status : sec_since_disconnect: optional string, containing an  integer,
       at least 0
              The amount of time since this manager last disconnected from the
              database (in seconds). Value is empty if manager has never  dis‐
              connected.

       status : locks_held: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection holds.  Omitted if the  connection  does  not  hold  any
              locks.

       status : locks_waiting: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection is currently waiting to acquire.  Omitted if the connec‐
              tion is not waiting for any locks.

       status : locks_lost: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection has had stolen by another OVSDB client.  Omitted  if  no
              locks have been stolen from this connection.

       status  :  n_connections:  optional  string,  containing an integer, at
       least 2
              When target specifies  a  connection  method  that  listens  for
              inbound connections (e.g. ptcp: or pssl:) and more than one con‐
              nection is actually active, the value is the  number  of  active
              connections.  Otherwise, this key-value pair is omitted.

              When  multiple  connections  are active, status columns and key-
              value pairs (other than this one) report the status of one arbi‐
              trarily chosen connection.

       status : bound_port: optional string, containing an integer
              When target is ptcp: or pssl:, this is the TCP port on which the
              OVSDB server is listening.  (This is is particularly useful when
              target  specifies a port of 0, allowing the kernel to choose any
              available port.)

     Connection Parameters:
       Additional configuration for a connection between the manager  and  the
       Open vSwitch Database.

       other_config : dscp: optional string, containing an integer
              The  Differentiated Service Code Point (DSCP) is specified using
              6 bits in the Type of Service (TOS) field in the IP header. DSCP
              provides a mechanism to classify the network traffic and provide
              Quality of Service (QoS) on IP networks.  The DSCP value  speci‐
              fied  here  is used when establishing the connection between the
              manager and the Open vSwitch.   If  no  value  is  specified,  a
              default value of 48 is chosen.  Valid DSCP values must be in the
              range 0 to 63.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

NetFlow TABLE
       A  NetFlow  target.   NetFlow  is  a  protocol that exports a number of
       details about terminating IP flows, such as the principals involved and
       duration.

   Summary:
       targets                       set of 1 or more strings
       engine_id                     optional integer, in range 0 to 255
       engine_type                   optional integer, in range 0 to 255
       active_timeout                integer, at least -1
       add_id_to_interface           boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of 1 or more strings
              NetFlow  targets  in the form ip:port.  The ip must be specified
              numerically, not as a DNS name.

       engine_id: optional integer, in range 0 to 255
              Engine ID to use in  NetFlow  messages.   Defaults  to  datapath
              index if not specified.

       engine_type: optional integer, in range 0 to 255
              Engine  type  to  use in NetFlow messages.  Defaults to datapath
              index if not specified.

       active_timeout: integer, at least -1
              The interval at which NetFlow records are sent  for  flows  that
              are still active, in seconds.  A value of 0 requests the default
              timeout (currently 600 seconds); a value of -1  disables  active
              timeouts.

              The  NetFlow passive timeout, for flows that become inactive, is
              not configurable.  It will vary depending on  the  Open  vSwitch
              version, the forms and contents of the OpenFlow flow tables, CPU
              and memory usage, and network activity.  A typical passive time‐
              out is about a second.

       add_id_to_interface: boolean
              If  this  column’s value is false, the ingress and egress inter‐
              face fields of NetFlow flow records are  derived  from  OpenFlow
              port  numbers.   When it is true, the 7 most significant bits of
              these fields will be replaced by the least significant 7 bits of
              the  engine  id.  This is useful because many NetFlow collectors
              do not expect multiple switches to be sending messages from  the
              same  host,  so  they  do not store the engine information which
              could be used to disambiguate the traffic.

              When this option is enabled, a maximum of  508  ports  are  sup‐
              ported.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

SSL TABLE
       SSL configuration for an Open_vSwitch.

   Summary:
       private_key                   string
       certificate                   string
       ca_cert                       string
       bootstrap_ca_cert             boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       private_key: string
              Name of a PEM file  containing  the  private  key  used  as  the
              switch’s identity for SSL connections to the controller.

       certificate: string
              Name  of a PEM file containing a certificate, signed by the cer‐
              tificate authority (CA) used by the controller and manager, that
              certifies  the  switch’s  private key, identifying a trustworthy
              switch.

       ca_cert: string
              Name of a PEM file containing the CA certificate used to  verify
              that the switch is connected to a trustworthy controller.

       bootstrap_ca_cert: boolean
              If  set to true, then Open vSwitch will attempt to obtain the CA
              certificate from the controller on its first SSL connection  and
              save  it  to  the  named  PEM file. If it is successful, it will
              immediately drop the connection and reconnect, and from then  on
              all  SSL  connections  must  be  authenticated  by a certificate
              signed by the CA certificate thus obtained.  This option exposes
              the  SSL  connection to a man-in-the-middle attack obtaining the
              initial CA certificate.  It may still be useful  for  bootstrap‐
              ping.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

sFlow TABLE
       A set of sFlow(R) targets.  sFlow is a protocol for  remote  monitoring
       of switches.

   Summary:
       agent                         optional string
       header                        optional integer
       polling                       optional integer
       sampling                      optional integer
       targets                       set of 1 or more strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       agent: optional string
              Name  of  the network device whose IP address should be reported
              as the ``agent address’’ to collectors.  If not  specified,  the
              agent  device  is  figured from the first target address and the
              routing table.  If the routing table does not contain a route to
              the  target, the IP address defaults to the local_ip in the col‐
              lector’s Controller.  If an agent IP address  cannot  be  deter‐
              mined any of these ways, sFlow is disabled.

       header: optional integer
              Number  of  bytes  of a sampled packet to send to the collector.
              If not specified, the default is 128 bytes.

       polling: optional integer
              Polling rate in seconds to send port statistics to  the  collec‐
              tor.  If not specified, defaults to 30 seconds.

       sampling: optional integer
              Rate  at which packets should be sampled and sent to the collec‐
              tor.  If not specified, defaults to 400, which means one out  of
              400 packets, on average, will be sent to the collector.

       targets: set of 1 or more strings
              sFlow targets in the form ip:port.

     Common Columns:
       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

IPFIX TABLE
       Configuration for sending packets to IPFIX collectors.

       IPFIX is a protocol that exports a number of details about flows.   The
       IPFIX  implementation in Open vSwitch samples packets at a configurable
       rate, extracts flow information from those packets,  optionally  caches
       and  aggregates  the  flow  information, and sends the result to one or
       more collectors.

       IPFIX in Open vSwitch can be configured two different ways:

              ·      With per-bridge sampling,  Open  vSwitch  performs  IPFIX
                     sampling automatically on all packets that pass through a
                     bridge.  To  configure  per-bridge  sampling,  create  an
                     IPFIX  record  and point a Bridge table’s ipfix column to
                     it.  The Flow_Sample_Collector_Set table is not used  for
                     per-bridge sampling.

              ·      With  flow-based sampling, sample actions in the OpenFlow
                     flow table drive IPFIX sampling.  See ovs-ofctl(8) for  a
                     description of the sample action.

                     Flow-based sampling also requires database configuration:
                     create a IPFIX record that describes the IPFIX configura‐
                     tion  and  a Flow_Sample_Collector_Set record that points
                     to the Bridge whose flow table holds the  sample  actions
                     and  to  IPFIX  record.  The ipfix in the Bridge table is
                     not used for flow-based sampling.

   Summary:
       targets                       set of strings
       cache_active_timeout          optional integer, in range 0 to 4,200
       cache_max_flows               optional   integer,   in   range   0   to
                                     4,294,967,295
       Per-Bridge Sampling:
         sampling                    optional   integer,   in   range   1   to
                                     4,294,967,295
         obs_domain_id               optional   integer,   in   range   0   to
                                     4,294,967,295
         obs_point_id                optional   integer,   in   range   0   to
                                     4,294,967,295
         other_config : enable-tunnel-sampling
                                     optional string, either true or false
         other_config : enable-input-sampling
                                     optional string, either true or false
         other_config : enable-output-sampling
                                     optional string, either true or false
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of strings
              IPFIX target collectors in the form ip:port.

       cache_active_timeout: optional integer, in range 0 to 4,200
              The maximum period in seconds for which an IPFIX flow record  is
              cached  and  aggregated  before  being  sent.  If not specified,
              defaults to 0.  If 0, caching is disabled.

       cache_max_flows: optional integer, in range 0 to 4,294,967,295
              The maximum number of IPFIX flow records that can be cached at a
              time.   If  not specified, defaults to 0.  If 0, caching is dis‐
              abled.

     Per-Bridge Sampling:
       These values affect only per-bridge sampling.  See above for a descrip‐
       tion of the differences between per-bridge and flow-based sampling.

       sampling: optional integer, in range 1 to 4,294,967,295
              The  rate  at  which  packets should be sampled and sent to each
              target collector.  If not  specified,  defaults  to  400,  which
              means  one  out of 400 packets, on average, will be sent to each
              target collector.

       obs_domain_id: optional integer, in range 0 to 4,294,967,295
              The IPFIX Observation Domain ID sent in each IPFIX  packet.   If
              not specified, defaults to 0.

       obs_point_id: optional integer, in range 0 to 4,294,967,295
              The  IPFIX  Observation Point ID sent in each IPFIX flow record.
              If not specified, defaults to 0.

       other_config : enable-tunnel-sampling: optional string, either true  or
       false
              Set  to  true  to  enable  sampling  and reporting tunnel header
              7-tuples in IPFIX flow records.  Tunnel sampling is disabled  by
              default.

              The  following  enterprise  entities  report  the sampled tunnel
              info:

              tunnelType:
                     ID: 891, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description: Identifier of the layer  2  network  overlay
                     network  encapsulation  type:  0x01 VxLAN, 0x02 GRE, 0x03
                     LISP, 0x05 IPsec+GRE, 0x07 GENEVE.

              tunnelKey:
                     ID: 892, and enterprise ID 6876 (VMware).

                     type: variable-length octetarray.

                     data type semantics: identifier.

                     description: Key which is used for identifying  an  indi‐
                     vidual  traffic  flow within a VxLAN (24-bit VNI), GENEVE
                     (24-bit VNI), GRE (32-bit key), or LISP (24-bit  instance
                     ID)  tunnel.  The  key is encoded in this octetarray as a
                     3-, 4-, or 8-byte integer ID in network byte order.

              tunnelSourceIPv4Address:
                     ID: 893, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description: The IPv4 source address  in  the  tunnel  IP
                     packet header.

              tunnelDestinationIPv4Address:
                     ID: 894, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description:  The  IPv4 destination address in the tunnel
                     IP packet header.

              tunnelProtocolIdentifier:
                     ID: 895, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description: The value of the protocol number in the tun‐
                     nel  IP packet header. The protocol number identifies the
                     tunnel IP packet payload type.

              tunnelSourceTransportPort:
                     ID: 896, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description: The source port  identifier  in  the  tunnel
                     transport  header.  For the transport protocols UDP, TCP,
                     and SCTP, this is the source port  number  given  in  the
                     respective header.

              tunnelDestinationTransportPort:
                     ID: 897, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description:  The destination port identifier in the tun‐
                     nel transport header. For the  transport  protocols  UDP,
                     TCP,  and SCTP, this is the destination port number given
                     in the respective header.

       other_config : enable-input-sampling: optional string, either  true  or
       false
              By  default,  Open  vSwitch  samples and reports flows at bridge
              port input in IPFIX flow records.  Set this column to  false  to
              disable input sampling.

       other_config  : enable-output-sampling: optional string, either true or
       false
              By default, Open vSwitch samples and  reports  flows  at  bridge
              port  output in IPFIX flow records.  Set this column to false to
              disable output sampling.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

Flow_Sample_Collector_Set TABLE
       A  set of IPFIX collectors of packet samples generated by OpenFlow sam
       ple actions.  This table is used only for  IPFIX  flow-based  sampling,
       not  for  per-bridge sampling (see the IPFIX table for a description of
       the two forms).

   Summary:
       id                            integer, in range 0 to 4,294,967,295
       bridge                        Bridge
       ipfix                         optional IPFIX
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       id: integer, in range 0 to 4,294,967,295
              The ID of this collector set, unique among the bridge’s  collec‐
              tor  sets, to be used as the collector_set_id in OpenFlow sample
              actions.

       bridge: Bridge
              The bridge into which OpenFlow sample actions can  be  added  to
              send packet samples to this set of IPFIX collectors.

       ipfix: optional IPFIX
              Configuration  of  the  set of IPFIX collectors to send one flow
              record per sampled packet to.

     Common Columns:
       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

AutoAttach TABLE
       Auto  Attach  configuration within a bridge.  The IETF Auto-Attach SPBM
       draft standard describes a compact method of using  IEEE  802.1AB  Link
       Layer  Discovery  Protocol (LLDP) together with a IEEE 802.1aq Shortest
       Path Bridging (SPB) network to automatically attach network devices  to
       individual services in a SPB network.  The intent here is to allow net‐
       work applications and devices using OVS  to  be  able  to  easily  take
       advantage of features offered by industry standard SPB networks.

       Auto  Attach (AA) uses LLDP to communicate between a directly connected
       Auto Attach Client (AAC) and Auto Attach Server (AAS). The LLDP  proto‐
       col  is  extended  to  add two new Type-Length-Value tuples (TLVs). The
       first new TLV supports the ongoing discovery of directly  connected  AA
       correspondents.  Auto Attach operates by regularly transmitting AA dis‐
       covery TLVs between the AA client and AA server.  By  exchanging  these
       discovery messages, both the AAC and AAS learn the system name and sys‐
       tem description of their peer. In the OVS context, OVS operates as  the
       AA  client and the AA server resides on a switch at the edge of the SPB
       network.

       Once AA discovery has been completed the AAC then uses the  second  new
       TLV  to  deliver identifier mappings from the AAC to the AAS. A primary
       feature of Auto Attach is to facilitate the mapping  of  VLANs  defined
       outside the SPB network onto service ids (ISIDs) defined within the SPM
       network. By doing so individual external VLANs can be mapped onto  spe‐
       cific  SPB network services. These VLAN id to ISID mappings can be con‐
       figured and managed locally using new options added  to  the  ovs-vsctl
       command.

       The  Auto  Attach OVS feature does not provide a full implementation of
       the LLDP protocol. Support for the mandatory TLVs  as  defined  by  the
       LLDP  standard  and support for the AA TLV extensions is provided. LLDP
       protocol support in OVS can be enabled or disabled on a  port  by  port
       basis. LLDP support is disabled by default.

   Summary:
       system_name                   string
       system_description            string
       mappings                      map  of  integer-integer  pairs,  key  in
                                     range 0 to 16,777,215, value in  range  0
                                     to 4,095

   Details:
       system_name: string
              The  system_name string is exported in LLDP messages.  It should
              uniquely identify the bridge in the network.

       system_description: string
              The system_description string is exported in LLDP messages.   It
              should describe the type of software and hardware.

       mappings:  map  of integer-integer pairs, key in range 0 to 16,777,215,
       value in range 0 to 4,095
              A mapping from SPB network Individual Service Identifier  (ISID)
              to VLAN id.



Open vSwitch 2.5.1              DB Schema 7.12.1       ovs-vswitchd.conf.db(5)