[ovs-discuss] IGMP snooping behavior with regards to Querier

[Ajit Warrier]

Thanks Cascardo,

I am on 2.4.0.

I delved into the source code, and it seems that it is because the querier
sets its IPv4 source address to 0.0.0.0. I understand that this is in
accordance with the RFC 4541 (Section 2.1.1.1 - 1(b)), so I guess this is
indeed the correct behavior.

Would you know why the RFC setup this rule ? I would assume this would
create issues in setups like ours, where:

- there is no Multicast router in the network (all traffic originates and
terminates within the LAN).
- there are multiple OVS software switches hooked up with each other.
- an IGMP querier is setup to allow IGMP snooping switches to populate
their tables correctly.

Thanks,
Ajit.

On Sun, 24 Jul 2016 at 10:11 Thadeu Lima de Souza Cascardo <
cascardo at redhat.com> wrote:

> On Sun, Jul 24, 2016 at 04:23:59PM +0000, Ajit Warrier wrote:
> > I am testing the IGMP snooping behavior in OVS 2.4 with the following
> setup:
> >
> > OVS1-------------eth0--------------------OVS2
> > |                                         |
> > |                                         |
> > eth1                                    eth1 ------- IGMP Querier
> > |                                         |
> > |                                         |
> > Laptop1                                Laptop2
> >
> > OVS1 and OVS2 are embedded devices running OVS-2.4 with snooping enabled.
> > Laptop1 and Laptop2 have multicast listeners.
> >
> > Without the IGMP Querier, the IGMP join messages sent by Laptop1 stop at
> > OVS1 and do not continue on to OVS1. This is what I expected.
> >
> > Now I turn on an IGMP querier which sends general IGMP queries on
> > 224.0.0.1. I can see these queries going through OVS2 and arriving at
> OVS1.
> > Now further IGMP joins from Laptop1 should no longer be blocked by OVS1,
> > but should be forwarded on the port (eth0) that received an IGMP query. I
> > do not observe this behavior.
> >
> > Is this behavior not yet implemented in the current snooping
> implementation
> > ? Is there any configuration option to enable it ?
> >
> > Regards,
> > Ajit.
>
> Hi, Ajit.
>
> That is implemented. Some bugs have been fixed already. Can you try latest
> version at 2.4 branch? What exact version did you test?
>
> If the latest doesn't work, it could be a new bug, and I would appreciate
> your
> help in debugging it. But before we do it, we should verify for the latest
> fixes.
>
> Regards.
> Cascardo.
>
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