[ovs-discuss] Group Table timeouts in OVS/OpenFlow

[Adrian Pol]

Hi

I have a question that may be connected to OpenFlow, rather than with OVS.
But I'd appreciate if you can help me, since I'm just starting with OF. The
question is why do Group Tables not have timeout parameter?

Here is my use-case:
For each new packet I want to install flow entry with group action as
output (1 to 1). To keep the flow entries list as small as possible I'd
like to remove unused ones, so I set idle timeout on them. However, when
unused flow is wiped out from switch, the associated group is not. So I
have three options:
1 If I generate groups on demand I need to follow the status of the flow
with my service. Service has to be aware of idle timeout and issue group
remove message;
2 If I assume groups to be permanent, not generated on demand, I still have
to keep detail information on the controller (which output port, type of
group etc.)
3 Implement idle timeout for group inside my service, since when I remove
group from switch, the flows are removed as well

If I just neglect this problem and generate new flow entry and group action
after each packet in message (this is what I want), I will end up with huge
group table (and most of the entries will remain unused).

So again, if I can move switch flow table size management to the node, why
can't I do similar with group tables? Instead of adding above
functionalities in my service, it will be much easier if I can set idle
timeout on group action, which is equal to flow entry timeout.

Let me know if I missed something but I can't see anything simpler based on
OFv1.5 documentation.

Best regards,
Adrian Alan Pol
Technical University of Denmark
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://openvswitch.org/pipermail/ovs-discuss/attachments/20151211/d306d942/attachment-0002.html>