ovs-vswitchd(8)               Open vSwitch Manual              ovs-vswitchd(8)



NAME
       ovs-vswitchd - Open vSwitch daemon

SYNOPSIS
       ovs-vswitchd [database]

DESCRIPTION
       A  daemon that manages and controls any number of Open vSwitch switches
       on the local machine.

       The  database  argument  specifies   how   ovs-vswitchd   connects   to
       ovsdb-server.   The default is unix://var/run/openvswitch/db.sock.  The
       following forms are accepted:

       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) in IPv4 or IPv6
              address format.  If ip is an IPv6 address,  then  wrap  ip  with
              square   brackets,  e.g.:  ssl:[::1]:6640.   The  --private-key,
              --certificate, and --ca-cert options  are  mandatory  when  this
              form is used.

       tcp:ip:port
              Connect  to  the  given  TCP port on ip, where ip can be IPv4 or
              IPv6 address. If ip is an IPv6 address, then wrap ip with square
              brackets, e.g.: tcp:[::1]:6640.

       unix:file
              On POSIX, connect to the Unix domain server socket named file.

              On Windows, connect to a localhost TCP port whose value is writ‐
              ten in file.

       pssl:port[:ip]
              Listen on the given SSL port for a connection.  By default, con‐
              nections  are  not bound to a particular local IP address and it
              listens only on IPv4 (but not IPv6) addresses, but specifying ip
              limits  connections  to  those from the given ip, either IPv4 or
              IPv6 address.  If ip is an  IPv6  address,  then  wrap  ip  with
              square  brackets,  e.g.:  pssl:6640:[::1].   The  --private-key,
              --certificate, and --ca-cert options  are  mandatory  when  this
              form is used.

       ptcp:port[:ip]
              Listen on the given TCP port for a connection.  By default, con‐
              nections are not bound to a particular local IP address  and  it
              listens  only  on  IPv4  (but not IPv6) addresses, but ip may be
              specified to listen only for connections to the given ip, either
              IPv4  or  IPv6  address.  If ip is an IPv6 address, then wrap ip
              with square brackets, e.g.: ptcp:6640:[::1].

       punix:file
              On POSIX, listen on the Unix domain server socket named file for
              a connection.

              On Windows, listen on a kernel chosen TCP port on the localhost.
              The kernel chosen TCP port value is written in file.

       ovs-vswitchd retrieves its configuration from database at startup.   It
       sets  up Open vSwitch datapaths and then operates switching across each
       bridge described in its configuration files.  As the database  changes,
       ovs-vswitchd automatically updates its configuration to match.

       ovs-vswitchd  switches may be configured with any of the following fea‐
       tures:

       ·      L2 switching with MAC learning.

       ·      NIC bonding with automatic fail-over  and  source  MAC-based  TX
              load balancing ("SLB").

       ·      802.1Q VLAN support.

       ·      Port mirroring, with optional VLAN tagging.

       ·      NetFlow v5 flow logging.

       ·      sFlow(R) monitoring.

       ·      Connectivity to an external OpenFlow controller, such as NOX.

       Only a single instance of ovs-vswitchd is intended to run at a time.  A
       single ovs-vswitchd can manage any number of switch  instances,  up  to
       the maximum number of supported Open vSwitch datapaths.

       ovs-vswitchd  does  all  the necessary management of Open vSwitch data‐
       paths itself.  Thus, external tools, such ovs-dpctl(8), are not  needed
       for  managing datapaths in conjunction with ovs-vswitchd, and their use
       to modify datapaths when ovs-vswitchd is running can interfere with its
       operation.  (ovs-dpctl may still be useful for diagnostics.)

       An  Open vSwitch datapath kernel module must be loaded for ovs-vswitchd
       to be useful.  Please refer to the INSTALL.Linux file included  in  the
       Open vSwitch distribution for instructions on how to build and load the
       Open vSwitch kernel module.

OPTIONS
       --mlockall
              Causes ovs-vswitchd to call the mlockall() function, to  attempt
              to  lock all of its process memory into physical RAM, preventing
              the kernel from paging any of its memory to disk.  This helps to
              avoid networking interruptions due to system memory pressure.

              Some systems do not support mlockall() at all, and other systems
              only allow privileged users, such as the superuser, to  use  it.
              ovs-vswitchd emits a log message if mlockall() is unavailable or
              unsuccessful.

   DPDK Options
       --dpdk Initialize ovs-vswitchd DPDK datapath.   Refer  to  INSTALL.DPDK
              for details.

   Daemon Options
       The following options are valid on POSIX based platforms.

       --pidfile[=pidfile]
              Causes a file (by default, ovs-vswitchd.pid) to be created indi‐
              cating the PID of the running process.  If the pidfile  argument
              is  not  specified,  or  if it does not begin with /, then it is
              created in //var/run/openvswitch.

              If --pidfile is not specified, no pidfile is created.

       --overwrite-pidfile
              By default, when --pidfile is specified and the  specified  pid‐
              file  already  exists  and  is  locked  by  a  running  process,
              ovs-vswitchd refuses to start.  Specify  --overwrite-pidfile  to
              cause it to instead overwrite the pidfile.

              When --pidfile is not specified, this option has no effect.

       --detach
              Runs  ovs-vswitchd  as a background process.  The process forks,
              and in the child it starts a new session,  closes  the  standard
              file descriptors (which has the side effect of disabling logging
              to the console), and changes its current directory to  the  root
              (unless --no-chdir is specified).  After the child completes its
              initialization, the parent exits.   ovs-vswitchd  detaches  only
              after  it  has  connected to the database, retrieved the initial
              configuration, and set up that configuration.

       --monitor
              Creates an additional process to monitor the  ovs-vswitchd  dae‐
              mon.   If  the daemon dies due to a signal that indicates a pro‐
              gramming error (SIGABRT, SIGALRM, SIGBUS, SIGFPE,  SIGILL,  SIG
              PIPE,  SIGSEGV,  SIGXCPU,  or  SIGXFSZ) then the monitor process
              starts a new copy of it.   If  the  daemon  dies  or  exits  for
              another reason, the monitor process exits.

              This  option  is  normally used with --detach, but it also func‐
              tions without it.

       --no-chdir
              By default, when --detach is specified, ovs-vswitchd changes its
              current  working  directory  to  the  root  directory  after  it
              detaches.  Otherwise, invoking ovs-vswitchd  from  a  carelessly
              chosen directory would prevent the administrator from unmounting
              the file system that holds that directory.

              Specifying  --no-chdir  suppresses  this  behavior,   preventing
              ovs-vswitchd  from changing its current working directory.  This
              may be useful for collecting core  files,  since  it  is  common
              behavior  to write core dumps into the current working directory
              and the root directory is not a good directory to use.

              This option has no effect when --detach is not specified.

       --user Causes ovs-vswitchd to run as  a  different  user  specified  in
              "user:group",  thus  dropping most of the root privileges. Short
              forms "user" and ":group" are also allowed, with current user or
              group are assumed respectively. Only daemons started by the root
              user accepts this argument.

              On   Linux,   daemons   will   be   granted   CAP_IPC_LOCK   and
              CAP_NET_BIND_SERVICES  before  dropping root privileges. Daemons
              interact with datapath, such as ovs-vswitchd,  will  be  granted
              two    additional   capabilities,   namely   CAP_NET_ADMIN   and
              CAP_NET_RAW. The capability change will apply even if  new  user
              is "root".

              On Windows, this option is not currently supported. For security
              reasons, specifying this option will cause  the  daemon  process
              not to start.

   Service Options
       The following options are valid only on Windows platform.

       --service
              Causes  ovs-vswitchd  to run as a service in the background. The
              service should already have been created through external  tools
              like SC.exe.

       --service-monitor
              Causes the ovs-vswitchd service to be automatically restarted by
              the Windows services manager if the service dies  or  exits  for
              unexpected reasons.

              When --service is not specified, this option has no effect.

   Public Key Infrastructure Options
       -p privkey.pem
       --private-key=privkey.pem
              Specifies  a  PEM  file  containing  the  private  key  used  as
              ovs-vswitchd's identity for outgoing SSL connections.

       -c cert.pem
       --certificate=cert.pem
              Specifies a PEM file containing a certificate that certifies the
              private  key specified on -p or --private-key to be trustworthy.
              The certificate must be signed by the certificate authority (CA)
              that the peer in SSL connections will use to verify it.

       -C cacert.pem
       --ca-cert=cacert.pem
              Specifies   a  PEM  file  containing  the  CA  certificate  that
              ovs-vswitchd should use to verify certificates presented  to  it
              by  SSL peers.  (This may be the same certificate that SSL peers
              use to verify the certificate specified on -c or  --certificate,
              or  it  may  be  a different one, depending on the PKI design in
              use.)

       -C none
       --ca-cert=none
              Disables verification of certificates presented  by  SSL  peers.
              This  introduces a security risk, because it means that certifi‐
              cates cannot be verified to be those of known trusted hosts.

       --bootstrap-ca-cert=cacert.pem
              When cacert.pem exists, this option has the same effect as -C or
              --ca-cert.  If it does not exist, then ovs-vswitchd will attempt
              to obtain the CA certificate from the SSL peer on its first  SSL
              connection and save it to the named PEM file.  If it is success‐
              ful, it will immediately drop the connection and reconnect,  and
              from then on all SSL connections must be authenticated by a cer‐
              tificate 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, but it may be use‐
              ful for bootstrapping.

              This option is only useful if the SSL peer sends its CA certifi‐
              cate  as  part  of  the SSL certificate chain.  The SSL protocol
              does not require the server to send the CA certificate.

              This option is mutually exclusive with -C and --ca-cert.

   Logging Options
       -v[spec]
       --verbose=[spec]
              Sets logging levels.  Without any spec, sets the log  level  for
              every  module and destination to dbg.  Otherwise, spec is a list
              of words separated by spaces or commas or colons, up to one from
              each category below:

              ·      A  valid  module name, as displayed by the vlog/list com‐
                     mand on ovs-appctl(8), limits the log level change to the
                     specified module.

              ·      syslog,  console,  or file, to limit the log level change
                     to only to the system log, to the console, or to a  file,
                     respectively.   (If  --detach  is specified, ovs-vswitchd
                     closes its standard file descriptors, so logging  to  the
                     console will have no effect.)

                     On  Windows platform, syslog is accepted as a word and is
                     only useful along with the  --syslog-target  option  (the
                     word has no effect otherwise).

              ·      off,  emer,  err,  warn, info, or dbg, to control the log
                     level.  Messages of the given severity or higher will  be
                     logged,  and  messages of lower severity will be filtered
                     out.  off filters out all  messages.   See  ovs-appctl(8)
                     for a definition of each log level.

              Case is not significant within spec.

              Regardless  of  the  log  levels set for file, logging to a file
              will not take place unless --log-file  is  also  specified  (see
              below).

              For compatibility with older versions of OVS, any is accepted as
              a word but has no effect.

       -v
       --verbose
              Sets the maximum logging verbosity level, equivalent  to  --ver
              bose=dbg.

       -vPATTERN:destination:pattern
       --verbose=PATTERN:destination:pattern
              Sets  the  log  pattern  for  destination  to pattern.  Refer to
              ovs-appctl(8) for a description of the valid syntax for pattern.

       -vFACILITY:facility
       --verbose=FACILITY:facility
              Sets the RFC5424 facility of the log message.  facility  can  be
              one  of kern, user, mail, daemon, auth, syslog, lpr, news, uucp,
              clock, ftp, ntp, audit, alert, clock2, local0,  local1,  local2,
              local3,  local4, local5, local6 or local7. If this option is not
              specified, daemon is used as the default for  the  local  system
              syslog  and local0 is used while sending a message to the target
              provided via the --syslog-target option.

       --log-file[=file]
              Enables logging to a file.  If file is  specified,  then  it  is
              used  as  the exact name for the log file.  The default log file
              name   used   if   file   is    omitted    is    //var/log/open
              vswitch/ovs-vswitchd.log.

       --syslog-target=host:port
              Send  syslog  messages  to  UDP port on host, in addition to the
              system syslog.  The host must be a numerical IP address,  not  a
              hostname.

       --syslog-method=method
              Specify method how syslog messages should be sent to syslog dae‐
              mon.  Following forms are supported:

              ·      libc, use libc syslog() function.  This  is  the  default
                     behavior.   Downside  of  using this options is that libc
                     adds fixed prefix to every message before it is  actually
                     sent  to  the  syslog  daemon  over  /dev/log UNIX domain
                     socket.

              ·      unix:file, use UNIX domain socket directly.  It is possi‐
                     ble to specify arbitrary message format with this option.
                     However, rsyslogd 8.9 and older versions use  hard  coded
                     parser  function  anyway  that  limits UNIX domain socket
                     use.  If you want to use arbitrary  message  format  with
                     older rsyslogd versions, then use UDP socket to localhost
                     IP address instead.

              ·      udp:ip:port, use UDP socket.  With this method it is pos‐
                     sible  to  use  arbitrary  message format also with older
                     rsyslogd.  When sending syslog messages over  UDP  socket
                     extra  precaution  needs  to  be  taken into account, for
                     example, syslog daemon needs to be configured  to  listen
                     on  the  specified  UDP  port,  accidental iptables rules
                     could be interfering with local syslog traffic and  there
                     are  some security considerations that apply to UDP sock‐
                     ets, but do not apply to UNIX domain sockets.

   Other Options
       --unixctl=socket
              Sets the name of the control socket on which  ovs-vswitchd  lis‐
              tens  for  runtime  management  commands (see RUNTIME MANAGEMENT
              COMMANDS, below).  If socket does not begin with /, it is inter‐
              preted  as  relative  to //var/run/openvswitch.  If --unixctl is
              not  used  at  all,  the  default  socket   is   //var/run/open
              vswitch/ovs-vswitchd.pid.ctl,   where   pid   is  ovs-vswitchd's
              process ID.

              On Windows, uses a kernel chosen TCP port on  the  localhost  to
              listen  for  runtime management commands.  The kernel chosen TCP
              port value is written in a file whose absolute path  is  pointed
              by  socket. If --unixctl is not used at all, the file is created
              as ovs-vswitchd.ctl in the configured OVS_RUNDIR directory.

              Specifying none for socket disables the control socket feature.

       -h
       --help Prints a brief help message to the console.

       -V
       --version
              Prints version information to the console.

RUNTIME MANAGEMENT COMMANDS
       ovs-appctl(8) can send commands to a running ovs-vswitchd process.  The
       currently supported commands are described below.  The command descrip‐
       tions assume an understanding of how to configure Open vSwitch.

   GENERAL COMMANDS
       exit   Causes ovs-vswitchd to gracefully terminate.

       qos/show interface
              Queries the kernel for Quality of Service configuration and sta‐
              tistics associated with the given interface.

       bfd/show [interface]
              Displays  detailed  information  about  Bidirectional Forwarding
              Detection configured on interface.  If interface is  not  speci‐
              fied,  then  displays  detailed information about all interfaces
              with BFD enabled.

       bfd/set-forwarding [interface] status
              Force the fault status of the BFD module on  interface  (or  all
              interfaces  if  none  is  given)  to  be  status.  status can be
              "true", "false", or  "normal"  which  reverts  to  the  standard
              behavior.

       cfm/show [interface]
              Displays  detailed  information about Connectivity Fault Manage‐
              ment configured on interface.  If interface  is  not  specified,
              then displays detailed information about all interfaces with CFM
              enabled.

       cfm/set-fault [interface] status
              Force the fault status of the CFM module on  interface  (or  all
              interfaces  if  none  is  given)  to  be  status.  status can be
              "true", "false", or  "normal"  which  reverts  to  the  standard
              behavior.

       stp/tcn [bridge]
              Forces  a  topology  change event on bridge if it's running STP.
              This may cause it to send Topology Change Notifications  to  its
              peers and flush its MAC table..  If no bridge is given, forces a
              topology change event on all bridges.

   BRIDGE COMMANDS
       These commands manage bridges.

       fdb/flush [bridge]
              Flushes bridge MAC  address  learning  table,  or  all  learning
              tables if no bridge is given.

       fdb/show bridge
              Lists  each  MAC  address/VLAN  pair  learned  by  the specified
              bridge, along with the port on which it was learned and the  age
              of the entry, in seconds.

       mdb/flush [bridge]
              Flushes  bridge multicast snooping table, or all snooping tables
              if no bridge is given.

       mdb/show bridge
              Lists each multicast group/VLAN pair learned  by  the  specified
              bridge,  along with the port on which it was learned and the age
              of the entry, in seconds.

       bridge/reconnect [bridge]
              Makes bridge drop all of its OpenFlow controller connections and
              reconnect.   If  bridge  is not specified, then all bridges drop
              their controller connections and reconnect.

              This command might be useful for debugging  OpenFlow  controller
              issues.

       bridge/dump-flows bridge
              Lists  all  flows  in bridge, including those normally hidden to
              commands such as ovs-ofctl dump-flows.  Flows set up  by  mecha‐
              nisms  such as in-band control and fail-open are hidden from the
              controller since it is not allowed to modify or override them.

   BOND COMMANDS
       These commands manage bonded ports on an Open  vSwitch's  bridges.   To
       understand  some  of  these  commands,  it is important to understand a
       detail of the bonding implementation called ``source  load  balancing''
       (SLB).   Instead  of  directly  assigning  Ethernet source addresses to
       slaves, the bonding implementation computes a  function  that  maps  an
       48-bit  Ethernet  source  addresses into an 8-bit value (a ``MAC hash''
       value).  All of the Ethernet addresses that map to a single 8-bit value
       are then assigned to a single slave.

       bond/list
              Lists all of the bonds, and their slaves, on each bridge.

       bond/show [port]
              Lists  all of the bond-specific information (updelay, downdelay,
              time until the next rebalance) about the given bonded  port,  or
              all  bonded  ports  if no port is given.  Also lists information
              about each slave: whether it is enabled or disabled, the time to
              completion  of  an  updelay  or downdelay if one is in progress,
              whether it is the active  slave,  the  hashes  assigned  to  the
              slave.   Any  LACP information related to this bond may be found
              using the lacp/show command.

       bond/migrate port hash slave
              Only valid for SLB bonds.  Assigns a given MAC  hash  to  a  new
              slave.   port  specifies  the bond port, hash the MAC hash to be
              migrated (as a decimal number between 0 and 255), and slave  the
              new slave to be assigned.

              The reassignment is not permanent: rebalancing or fail-over will
              cause the MAC hash to be shifted to a new  slave  in  the  usual
              manner.

              A MAC hash cannot be migrated to a disabled slave.

       bond/set-active-slave port slave
              Sets slave as the active slave on port.  slave must currently be
              enabled.

              The setting is  not  permanent:  a  new  active  slave  will  be
              selected if slave becomes disabled.

       bond/enable-slave port slave
       bond/disable-slave port slave
              Enables (or disables) slave on the given bond port, skipping any
              updelay (or downdelay).

              This setting is not permanent: it persists only until  the  car‐
              rier status of slave changes.

       bond/hash mac [vlan] [basis]
              Returns the hash value which would be used for mac with vlan and
              basis if specified.

       lacp/show [port]
              Lists all of the LACP related information about the given  port:
              active or passive, aggregation key, system id, and system prior‐
              ity.  Also lists information about each  slave:  whether  it  is
              enabled or disabled, whether it is attached or detached, port id
              and priority, actor information, and  partner  information.   If
              port  is not specified, then displays detailed information about
              all interfaces with CFM enabled.

   DPCTL DATAPATH DEBUGGING COMMANDS
       The primary way to configure ovs-vswitchd is through the  Open  vSwitch
       database,  e.g. using ovs-vsctl(8).  These commands provide a debugging
       interface for managing datapaths.  They  implement  the  same  features
       (and syntax) as ovs-dpctl(8).  Unlike ovs-dpctl(8), these commands work
       with datapaths that are integrated into ovs-vswitchd (e.g.  the  netdev
       datapath type).

       dpctl/add-dp dp [netdev[,option]...]
              Creates datapath dp, with a local port also named dp.  This will
              fail if a network device dp already exists.

              If netdevs are specified, ovs-vswitchd  adds  them  to  the  new
              datapath, just as if add-if was specified.

       dpctl/del-dp dp
              Deletes  datapath  dp.   If  dp  is  associated with any network
              devices, they are automatically removed.

       dpctl/add-if dp netdev[,option]...
              Adds each netdev to the set of network devices datapath dp moni‐
              tors,  where  dp is the name of an existing datapath, and netdev
              is the name of one of the host's  network  devices,  e.g.  eth0.
              Once a network device has been added to a datapath, the datapath
              has complete ownership of the network device's traffic  and  the
              network device appears silent to the rest of the system.

              A  netdev  may be followed by a comma-separated list of options.
              The following options are currently supported:

              type=type
                     Specifies the type of port to add.  The default  type  is
                     system.

              port_no=port
                     Requests  a specific port number within the datapath.  If
                     this option is not specified then one will  be  automati‐
                     cally assigned.

              key=value
                     Adds an arbitrary key-value option to the port's configu‐
                     ration.

              ovs-vswitchd.conf.db(5) documents the available port  types  and
              options.

       dpctl/set-if dp port[,option]...
              Reconfigures  each  port  in  dp as specified.  An option of the
              form key=value adds the specified key-value option to  the  port
              or  overrides  an  existing  key's value.  An option of the form
              key=, that is, without a value, deletes the key-value named key.
              The  type  and  port number of a port cannot be changed, so type
              and port_no are only allowed if they match the existing configu‐
              ration.

       dpctl/del-if dp netdev...
              Removes each netdev from the list of network devices datapath dp
              monitors.

       dpctl/dump-dps
              Prints the name of each configured datapath on a separate line.

       dpctl/show [-s | --statistics] [dp...]
              Prints a summary of configured datapaths, including their  data‐
              path  numbers  and  a  list of ports connected to each datapath.
              (The local port is identified as port 0.)  If -s or --statistics
              is specified, then packet and byte counters are also printed for
              each port.

              The datapath numbers consists of flow stats and mega  flow  mask
              stats.

              The  "lookups"  row  displays three stats related to flow lookup
              triggered by processing incoming packets in the datapath.  "hit"
              displays number of packets matches existing flows. "missed" dis‐
              plays the number of packets not matching any existing  flow  and
              require  user space processing.  "lost" displays number of pack‐
              ets destined for user space  process  but  subsequently  dropped
              before reaching userspace. The sum of "hit" and "miss" equals to
              the total number of packets datapath processed.

              The "flows" row displays the number of flows in datapath.

              The "masks" row displays the mega flow mask stats. This  row  is
              omitted  for datapath not implementing mega flow. "hit" displays
              the total number of masks visited for matching incoming packets.
              "total" displays number of masks in the datapath. "hit/pkt" dis‐
              plays the average number of masks visited per packet; the  ratio
              between "hit" and total number of packets processed by the data‐
              path".

              If one or more datapaths  are  specified,  information  on  only
              those datapaths are displayed.  Otherwise, ovs-vswitchd displays
              information about all configured datapaths.

   DATAPATH FLOW TABLE DEBUGGING COMMANDS
       The following commands are primarily useful for debugging Open vSwitch.
       The  flow  table entries (both matches and actions) that they work with
       are not OpenFlow flow entries.  Instead, they are different and consid‐
       erably simpler flows maintained by the Open vSwitch kernel module.  Use
       ovs-ofctl(8), instead, to work with OpenFlow flow entries.

       The dp argument to each of these commands is optional when exactly  one
       datapath exists, in which case that datapath is the default.  When mul‐
       tiple datapaths exist, then a datapath name is required.

       dpctl/dump-flows [-m | --more] [dp] [filter=filter]
              Prints to the console all flow entries in datapath dp's flow ta‐
              ble.   Without  -m  or  --more, output omits match fields that a
              flow wildcards entirely; with -m or --more, output includes  all
              wildcarded fields.

              If  filter=filter  is  specified,  only  displays the flows that
              match the filter. filter is a flow in the form similiar to  that
              accepted  by  ovs-ofctl(8)'s  add-flow  command. (This is not an
              OpenFlow flow: besides  other  differences,  it  never  contains
              wildcards.)   The  filter  is  also  useful  to match wildcarded
              fields   in   the   datapath   flow.   As   an   example,   fil
              ter='tcp,tp_src=100'  will  match  the  datapath flow containing
              'tcp(src=80/0xff00,dst=8080/0xff)'.

       dpctl/add-flow [dp] flow actions

       dpctl/mod-flow [--clear] [--may-create] [-s | --statistics]  [dp]  flow
       actions
              Adds  or  modifies a flow in dp's flow table that, when a packet
              matching flow arrives, causes actions to be executed.

              The add-flow command succeeds only  if  flow  does  not  already
              exist  in  dp.  Contrariwise, mod-flow without --may-create only
              modifies the actions for an existing flow.   With  --may-create,
              mod-flow will add a new flow or modify an existing one.

              If  -s  or  --statistics  is specified, then mod-flow prints the
              modified flow's statistics.  A flow's statistics are the  number
              of  packets  and  bytes  that  have passed through the flow, the
              elapsed time since the flow last processed a packet  (if  ever),
              and (for TCP flows) the union of the TCP flags processed through
              the flow.

              With --clear, mod-flow zeros out  the  flow's  statistics.   The
              statistics  printed  if -s or --statistics is also specified are
              those from just before clearing the statistics.

       dpctl/del-flow [-s | --statistics] [dp] flow
              Deletes the flow from dp's flow table that matches flow.  If  -s
              or  --statistics  is specified, then del-flow prints the deleted
              flow's statistics.

       dpctl/get-flow [dp] ufid:ufid
              Fetches the flow from dp's flow  table  with  unique  identifier
              ufid.   ufid  must  be  specified  as a string of 32 hexadecimal
              characters.

       dpctl/del-flows [dp]
              Deletes all flow entries from datapath dp's flow table.

   CONNECTION TRACKING TABLE DEBUGGING COMMANDS
       The following commands are primarily useful for debugging  the  connec‐
       tion tracking entries in the datapath.

       The  dp argument to each of these commands is optional when exactly one
       datapath exists, in which case that datapath is the default.  When mul‐
       tiple datapaths exist, then a datapath name is required.

       N.B.(Linux  specific): the system datapaths (i.e. the Linux kernel mod‐
       ule Open vSwitch datapaths) share a single  connection  tracking  table
       (which is also used by other kernel subsystems, such as iptables, nfta‐
       bles and the regular host stack).  Therefore, the following commands do
       not apply specifically to one datapath.

       dpctl/dump-conntrack [-m | --more] [-s | --statistics] [dp] [zone=zone]
              Prints  to the console all the connection entries in the tracker
              used by dp.  If zone=zone is specified, only shows  the  connec‐
              tions  in  zone.   With  --more,  some  implementation  specific
              details are included. With --statistics timeouts and  timestamps
              are added to the output.

       dpctl/flush-conntrack [dp] [zone=zone]
              Flushes  all  the  connection entries in the tracker used by dp.
              If zone=zone is specified, only flushes the connections in zone.

   DPIF-NETDEV COMMANDS
       These commands are used to expose internal information (mostly  statis‐
       tics)  about  the  ``dpif-netdev'' userspace datapath. If there is only
       one datapath (as is often the case, unless dpctl/ commands  are  used),
       the dp argument can be omitted.

       dpif-netdev/pmd-stats-show [dp]
              Shows performance statistics for each pmd thread of the datapath
              dp.  The special thread ``main'' sums up the statistics of every
              non  pmd  thread.   The sum of ``emc hits'', ``masked hits'' and
              ``miss'' is the number of  packets  received  by  the  datapath.
              Cycles  are  counted  using  the TSC or similar facilities (when
              available on the platform).  To reset these counters  use  dpif-
              netdev/pmd-stats-clear. The duration of one cycle depends on the
              measuring infrastructure.

       dpif-netdev/pmd-stats-clear [dp]
              Resets to zero the per pmd thread performance numbers  shown  by
              the dpif-netdev/pmd-stats-show command.  It will NOT reset data‐
              path or bridge statistics, only the values shown  by  the  above
              command.

   DATAPATH DEBUGGING COMMANDS
       These  commands  query  and  modify datapaths.  They are are similar to
       ovs-dpctl(8) commands.  dpif/show  has  the  additional  functionality,
       beyond  dpctl/show  of  printing OpenFlow port numbers.  The other com‐
       mands are redundant and will be removed in a future release.

       dpif/dump-dps
              Prints the name of each configured datapath on a separate line.

       dpif/show
              Prints a summary of configured datapaths,  including  statistics
              and  a  list  of connected ports.  The port information includes
              the OpenFlow port number, datapath port number,  and  the  type.
              (The local port is identified as OpenFlow port 65534.)

       dpif/dump-flows [-m] dp
              Prints to the console all flow entries in datapath dp's flow ta‐
              ble. Without -m, output omits match fields that a flow wildcards
              entirely; with -m output includes all wildcarded fields.

              This  command  is  primarily  useful for debugging Open vSwitch.
              The flow table entries that it displays are  not  OpenFlow  flow
              entries.   Instead,  they are different and considerably simpler
              flows maintained by the datapath module.  If you wish to see the
              OpenFlow flow entries, use ovs-ofctl dump-flows.

       dpif/del-flows dp
              Deletes  all  flow  entries  from  datapath  dp's flow table and
              underlying datapath implementation (e.g., kernel  datapath  mod‐
              ule).

              This command is primarily useful for debugging Open vSwitch.  As
              discussed in dpif/dump-flows, these  entries  are  not  OpenFlow
              flow entries.

   OFPROTO COMMANDS
       These  commands  manage the core OpenFlow switch implementation (called
       ofproto).

       ofproto/list
              Lists the names of the running ofproto instances.  These are the
              names that may be used on ofproto/trace.

       ofproto/trace [dpname] odp_flow [-generate | packet]
       ofproto/trace bridge br_flow [-generate | packet]
       ofproto/trace-packet-out  [-consistent]  [dpname] odp_flow [-generate |
       packet] actions
       ofproto/trace-packet-out  [-consistent]  bridge  br_flow  [-generate  |
       packet] actions
              Traces  the  path  of  an  imaginary  packet  through switch and
              reports the path that it took.  The  initial  treatment  of  the
              packet varies based on the command:

              ·      ofproto/trace  looks  the  packet up in the OpenFlow flow
                     table, as if the packet had arrived on an OpenFlow port.

              ·      ofproto/trace-packet-out applies the  specified  OpenFlow
                     actions,  as  if  the  packet, flow, and actions had been
                     specified in an OpenFlow ``packet-out'' request.

              The packet's headers (e.g. source and destination) and  metadata
              (e.g. input port), together called its ``flow,'' are usually all
              that matter for the purpose of tracing a packet.  You can  spec‐
              ify the flow in the following ways:

              dpname odp_flow
                     odp_flow  is a flow in the form printed by ovs-dpctl(8)'s
                     dump-flows command.  If all of your bridges have the same
                     type, which is the common case, then you can omit dpname,
                     but if you have bridges of  different  types  (say,  both
                     ovs-netdev  and  ovs-system),  then you need to specify a
                     dpname to disambiguate.

              bridge br_flow
                     br_flow is a flow in the form similar to that accepted by
                     ovs-ofctl(8)'s  add-flow  command.  (This is not an Open‐
                     Flow flow: besides other differences, it  never  contains
                     wildcards.)   bridge  names  of  the bridge through which
                     br_flow should be traced.

              Most commonly, one specifies only a flow, using one of the forms
              above,  but sometimes one might need to specify an actual packet
              instead of just a flow:

              Side effects.
                     Some actions have side effects.  For example, the  normal
                     action  can  update the MAC learning table, and the learn
                     action can change OpenFlow tables.   The  trace  commands
                     only perform side effects when a packet is specified.  If
                     you want side effects to take place, then you must supply
                     a packet.

                     (Output  actions  are obviously side effects too, but the
                     trace commands never execute them, even when  one  speci‐
                     fies a packet.)

              Incomplete information.
                     Most  of the time, Open vSwitch can figure out everything
                     about the path of a packet using just the  flow,  but  in
                     some  special  circumstances it needs to look at parts of
                     the packet that are not included in the flow.  When  this
                     is the case, and you do not supply a packet, then a trace
                     command will tell you it needs a packet.

              If you wish to include a packet as part of  a  trace  operation,
              there are two ways to do it:

              -generate
                     This  option,  added to one of the ways to specify a flow
                     already described, causes Open vSwitch to internally gen‐
                     erate  a  packet  with the flow described and then to use
                     that packet.  If your goal is to  execute  side  effects,
                     then -generate is the easiest way to do it, but -generate
                     is not a good way  to  fill  in  incomplete  information,
                     because  it  generates  packets  based  on  only the flow
                     information, which means that the packets really  do  not
                     have any more information than the flow.

              packet This  form  supplies  an explicit packet as a sequence of
                     hex digits.  An Ethernet frame is at least 14 bytes long,
                     so  there  must be at least 28 hex digits.  Obviously, it
                     is inconvenient to type in the hex digits by hand, so the
                     ovs-pcap(1) and ovs-tcpundump(1) utilities provide easier
                     ways.

                     With this form, packet  headers  are  extracted  directly
                     from  packet,  so  the odp_flow or br_flow should specify
                     only metadata. The metadata can be:

                     skb_priority
                            Packet QoS priority.

                     pkt_mark
                            Mark of the packet.

                     ct_state
                            Connection state of the packet.

                     ct_zone
                            Connection tracking zone for packet.

                     ct_mark
                            Connection mark of the packet.

                     ct_label
                            Connection label of the packet.

                     tun_id The tunnel ID on which the packet arrived.

                     in_port
                            The port on which the packet arrived.

              The in_port value is kernel datapath port number for  the  first
              format  and OpenFlow port number for the second format. The num‐
              bering of these two types of port usually differs and  there  is
              no relationship.

              ofproto-trace-packet-out   accepts   an  additional  -consistent
              option.  With this option specified, the command rejects actions
              that are inconsistent with the specified packet.  (An example of
              an inconsistency is attempting to strip  the  VLAN  tag  from  a
              packet  that  does  not  have a VLAN tag.)  Open vSwitch ignores
              most forms of inconsistency in OpenFlow 1.0 and  rejects  incon‐
              sistencies  in later versions of OpenFlow.  The option is neces‐
              sary because the command does not ordinarily imply a  particular
              OpenFlow  version.  One exception is that, when actions includes
              an action that only OpenFlow 1.1 and  later  supports  (such  as
              push_vlan), -consistent is automatically enabled.

       ofproto/self-check [switch]
              Runs an internal consistency check on switch, if specified, oth‐
              erwise on all ofproto instances, and responds with a brief  sum‐
              mary  of  the  results.  If the summary reports any errors, then
              the Open vSwitch logs should contain more detailed  information.
              Please  pass  along  errors reported by this command to the Open
              vSwitch developers as bugs.

   VLOG COMMANDS
       These commands manage ovs-vswitchd's logging settings.

       vlog/set [spec]
              Sets logging levels.  Without any spec, sets the log  level  for
              every  module and destination to dbg.  Otherwise, spec is a list
              of words separated by spaces or commas or colons, up to one from
              each category below:

              ·      A  valid  module name, as displayed by the vlog/list com‐
                     mand on ovs-appctl(8), limits the log level change to the
                     specified module.

              ·      syslog,  console,  or file, to limit the log level change
                     to only to the system log, to the console, or to a  file,
                     respectively.

                     On  Windows platform, syslog is accepted as a word and is
                     only useful along with the  --syslog-target  option  (the
                     word has no effect otherwise).

              ·      off,  emer,  err,  warn, info, or dbg, to control the log
                     level.  Messages of the given severity or higher will  be
                     logged,  and  messages of lower severity will be filtered
                     out.  off filters out all  messages.   See  ovs-appctl(8)
                     for a definition of each log level.

              Case is not significant within spec.

              Regardless  of  the  log  levels set for file, logging to a file
              will not take place unless ovs-vswitchd  was  invoked  with  the
              --log-file option.

              For compatibility with older versions of OVS, any is accepted as
              a word but has no effect.

       vlog/set PATTERN:destination:pattern
              Sets the log pattern  for  destination  to  pattern.   Refer  to
              ovs-appctl(8) for a description of the valid syntax for pattern.

       vlog/list
              Lists the supported logging modules and their current levels.

       vlog/list-pattern
              Lists logging patterns used for each destination.

       vlog/reopen
              Causes  ovs-vswitchd to close and reopen its log file.  (This is
              useful after rotating log files, to cause a new log file  to  be
              used.)

              This  has  no  effect  unless  ovs-vswitchd was invoked with the
              --log-file option.

       vlog/disable-rate-limit [module]...
       vlog/enable-rate-limit [module]...
              By default, ovs-vswitchd limits the rate at which  certain  mes‐
              sages  can  be  logged.   When  a message would appear more fre‐
              quently than the limit,  it  is  suppressed.   This  saves  disk
              space,  makes  logs easier to read, and speeds up execution, but
              occasionally troubleshooting requires more  detail.   Therefore,
              vlog/disable-rate-limit allows rate limits to be disabled at the
              level of an individual log module.  Specify one or  more  module
              names, as displayed by the vlog/list command.  Specifying either
              no module names at all or the keyword any disables  rate  limits
              for every log module.

              The  vlog/enable-rate-limit command, whose syntax is the same as
              vlog/disable-rate-limit, can be used to re-enable a  rate  limit
              that was previously disabled.

   MEMORY COMMANDS
       These commands report memory usage.

       memory/show
              Displays  some  basic  statistics  about  ovs-vswitchd's  memory
              usage.  ovs-vswitchd  also  logs  this  information  soon  after
              startup and periodically as its memory consumption grows.

   COVERAGE COMMANDS
       These commands manage ovs-vswitchd's ``coverage counters,'' which count
       the number of times particular events occur during a daemon's  runtime.
       In addition to these commands, ovs-vswitchd automatically logs coverage
       counter values, at INFO level, when it detects that the  daemon's  main
       loop takes unusually long to run.

       Coverage counters are useful mainly for performance analysis and debug‐
       ging.

       coverage/show
              Displays the averaged per-second rates for the last few seconds,
              the  last  minute and the last hour, and the total counts of all
              of the coverage counters.

   OPENVSWITCH TUNNELING COMMANDS
       These commands query and modify OVS tunnel components. Ref  to  README-
       native-tunneling.md for more info.

       ovs/route/add ipv4_address/plen output_bridge [GW]
              Adds  ipv4_address/plen  route  to  vswitchd routing table. out‐
              put_bridge needs to be OVS bridge name.  This command is  useful
              if OVS cached routes does not look right.

       ovs/route/show
              Print  all  routes  in  OVS  routing table, This includes routes
              cached from system routing table and user configured routes.

       ovs/route/del ipv4_address/plen
              Delete ipv4_address/plen route from OVS routing table.

       tnl/neigh/show

       tnl/arp/show
              OVS builds ARP cache by  snooping  are  messages.  This  command
              shows ARP cache table.

       tnl/neigh/set bridge ip mac

       tnl/arp/set bridge ip mac
              Adds  or  modifies  an  ARP cache entry in bridge, mapping ip to
              mac.

       tnl/neigh/flush

       tnl/arp/flush
              Flush ARP table.

       tnl/egress_port_range [num1] [num2]
              Set range for UDP source port used for UDP  based  Tunnels.  For
              example  VxLAN.  If  case  of zero arguments this command prints
              current range in use.

OPENFLOW IMPLEMENTATION
       This section documents aspects of OpenFlow for which the OpenFlow spec‐
       ification requires documentation.

   Packet buffering.
       The OpenFlow specification, version 1.2, says:

              Switches  that  implement  buffering  are  expected  to  expose,
              through documentation, both the amount of  available  buffering,
              and the length of time before buffers may be reused.

       Open  vSwitch  maintains  a separate set of 256 packet buffers for each
       OpenFlow connection.  Any given packet buffer is preserved until it  is
       referenced by an OFPT_FLOW_MOD or OFPT_PACKET_OUT request or for 5 sec‐
       onds, whichever comes first.

LIMITS
       We believe these limits to be accurate as of this writing.  These  lim‐
       its assume the use of the Linux kernel datapath.

       ·      ovs-vswitchd  started  through  ovs-ctl(8)  provides  a limit of
              65535 file descriptors.  The limits on the number of bridges and
              ports  is decided by the availability of file descriptors.  With
              the Linux kernel datapath, creation of a single bridge  consumes
              three  file  descriptors  and adding a port consumes "n-handler-
              threads" file descriptors per  bridge  port.   Performance  will
              degrade  beyond  1,024  ports per bridge due to fixed hash table
              sizing.  Other platforms may have different limitations.

       ·      2,048 MAC learning entries per bridge,  by  default.   (This  is
              configurable  via  other-config:mac-table-size in the Bridge ta‐
              ble.  See ovs-vswitchd.conf.db(5) for details.)

       ·      Kernel flows are limited only by memory available to the kernel.
              Performance  will  degrade  beyond  1,048,576  kernel  flows per
              bridge with a 32-bit kernel, beyond 262,144 with a  64-bit  ker‐
              nel.  (ovs-vswitchd should never install anywhere near that many
              flows.)

       ·      OpenFlow flows are limited only by  available  memory.   Perfor‐
              mance is linear in the number of unique wildcard patterns.  That
              is, an OpenFlow table that contains many flows that all match on
              the  same fields in the same way has a constant-time lookup, but
              a table that contains many flows that match on different  fields
              requires lookup time linear in the number of flows.

       ·      255  ports per bridge participating in 802.1D Spanning Tree Pro‐
              tocol.

       ·      32 mirrors per bridge.

       ·      15 bytes for the name of a port.  (This is a Linux kernel  limi‐
              tation.)

SEE ALSO
       ovs-appctl(8),  ovsdb-server(1), INSTALL.Linux in the Open vSwitch dis‐
       tribution.



Open vSwitch                         2.5.1                     ovs-vswitchd(8)