[ovs-discuss] Use of ovs-vsctl with ovs-dpctl questions
jpettit at nicira.com
Mon Nov 9 10:07:55 PST 2009
On Nov 9, 2009, at 9:12 AM, John Galgay wrote:
> 1. What are the modes in which ovs-vsctl (switch) and ovs-dpctl
> work together .. or separately. And how do they relate to loading
> the openvswitch_mod.ko and brcompat_mod.ko modules?
I need to put up a better diagram of how all the components work, but
for now I can point you to a paper that we wrote:
Sections 3 and 4 describe the architecture of Open vSwitch. If you
look at Figure 2, ovs-dpctl controls the Fast Path and ovs-vsctl
configures the Slow Path. In general, you'll probably want to use ovs-
vsctl to handle configuration. ovs-dpctl is mostly useful for
debugging purposes. Since the datapath is essentially a cache for the
traffic that is occurring on the network, you can use the "ovs-dpctl
dump-flows" command to see what traffic is being processed and what
actions are occurring currently.
Neither of those commands will load the kernel modules.
> 2. Can I -or- Must I use the switch functions of ovs-vsctl in
> conjunction with the datapath functions of ovs-dpctl ... or are they
> exclusive from each other. In other words, can I get the benefits
> of the vswitch for bridging/switching and still define strict
> datapaths between ports on the switch?
They are essentially unrelated. I think your best bet may be to use
ovs-ofctl to setup static rules defining how traffic should move. For
example, you could define that port 1's traffic is sent to port 2 and
vice versa. Once you define those rules, the traffic that matches
them won't be switched according to a MAC table.
> 3. Are the ovs-dpctl capabilities tied to openflow? If not, cool.
> If so, can I use the openflow capabilities for datapaths without an
> openflow controller?
In Open vSwitch, the datapath (which ovs-dpctl controls) is just a
simple, fast forwarding table. ovs-vswitchd (or ofproto) contain an
OpenFlow module, which they then translate on-demand into datapath
Once again, you may want to look at ovs-ofctl, which sends OpenFlow
> 4. What are the best options regarding openflow controllers today?
The only one that I know of is NOX, which is available at
noxrepo.org. This is also a project hosted by Nicira.
> 5. Can an openflow controller also manage real 10G switches in the
> network (such as Arista with its EOS)?
The last I heard, Arista was reworking their OpenFlow port, so I don't
think it's publicly available. You can buy OpenFlow "real" switches
from NEC and Toroki. Most of the OpenFlow switches I know are 1G
switches that may support 10G uplinks. I know of some organizations
doing 10G ports, but I don't know when they will be available.
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