Open Stack

Hi,

Have a look at the agent code, search for <bridgename>.add_flow calls:
https://github.com/openstack/neutron/blob/master/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py

That in turn calls into run_ofctl here:
https://github.com/openstack/neutron/blob/master/neutron/agent/linux/ovs_lib.py

Which executes this command:
http://openvswitch.org/cgi-bin/ovsman.cgi?page=utilities%2Fovs-ofctl.8

I hope this helps.

Best,
Zoltan

From: Mark Maglana [mailto:mmaglana at gmail.com]
Sent: Friday, September 26, 2014 6:27 PM
To: Mengert, Robert
Cc: openstack at lists.openstack.org
Subject: Re: [Openstack] understanding flows of ovs in openstack

OVS n00b here too :-)

From what I've understood thus far, the controller sets the flows. OVS doesn't set any on its own.

Shameless plug: you can optionally play around with OVS using the ovs-lab vagrant project: http://www.relaxdiego.com/2014/09/ovs-lab.html

Regards,

Mark

On Friday, September 26, 2014, Mengert, Robert <Robert.Mengert at charter.com<mailto:Robert.Mengert at charter.com>> wrote:
Hey Srinivas,

I’m an OpenStack newbie but just started working through some of the same questions (experienced folks, please chime in if I’m spurting nonsense here).  I’ve found that reading up on Open vSwitch independently has been very helpful, their documentation can be found here<http://openvswitch.org/support/>.  Their FAQ<http://git.openvswitch.org/cgi-bin/gitweb.cgi?p=openvswitch;a=blob_plain;f=FAQ;hb=HEAD> is quite extensive but is a good read thus far (I’m only about halfway through it).

Some of the commands to view flows are well documented in the FAQ:

Q: Why are there so many different ways to dump flows?

A: Open vSwitch has two kinds of flows (see the previous question), so
   it has commands with different purposes for dumping each kind of
   flow:

      - "ovs-ofctl dump-flows <br>" dumps OpenFlow flows, excluding
        hidden flows.  This is the most commonly useful form of flow
        dump.  (Unlike the other commands, this should work with any
        OpenFlow switch, not just Open vSwitch.)

      - "ovs-appctl bridge/dump-flows <br>" dumps OpenFlow flows,
        including hidden flows.  This is occasionally useful for
        troubleshooting suspected issues with in-band control.

      - "ovs-dpctl dump-flows [dp]" dumps the datapath flow table
        entries for a Linux kernel-based datapath.  In Open vSwitch
        1.10 and later, ovs-vswitchd merges multiple switches into a
        single datapath, so it will show all the flows on all your
        kernel-based switches.  This command can occasionally be
        useful for debugging.

      - "ovs-appctl dpif/dump-flows <br>", new in Open vSwitch 1.10,
        dumps datapath flows for only the specified bridge, regardless
        of the type.

I haven’t gotten to how Open vSwitch populates the flows yet without the use of an SDN controller.  I’m a network guy by trade so I imagine there’s some type of learning at layer 2 happening similar to standard Ethernet switching.  Can anyone confirm?

Thanks,
Rob

From: Srinivasreddy R [mailto:srinivasreddy4390 at gmail.com<javascript:_e(%7B%7D,'cvml','srinivasreddy4390 at gmail.com');>]
Sent: Friday, September 26, 2014 7:19 AM
To: openstack at lists.openstack.org<javascript:_e(%7B%7D,'cvml','openstack at lists.openstack.org');>
Subject: [Openstack] understanding flows of ovs in openstack

hi ,
i want to understand  the role of openvswitch  in openstack .
how and what flows are configured  in both compute and networknode .
please suggest .
thanks,
srinivas.
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