Re: [magma] igmp snooping
Marshall Eubanks <marshall.eubanks@gmail.com> Tue, 25 October 2005 16:17 UTC
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Date: Tue, 25 Oct 2005 12:17:02 -0400
From: Marshall Eubanks <marshall.eubanks@gmail.com>
To: "Shenoy, Vivekananda (Vivek)" <vshenoy@riverstonenet.com>
Subject: Re: [magma] igmp snooping
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Hello; Maybe I am misunderstanding something, but I don't think that there is a problem : RFC 2236 and 3376 are pretty similar here. >From RFC 2236 On startup, a router SHOULD send [Startup Query Count] General Queries spaced closely together [Startup Query Interval] in order to quickly and reliably determine membership information. A General Query is addressed to the all-systems multicast group (224.0.0.1), has a Group Address field of 0, and has a Max Response Time of [Query Response Interval]. So the switch should also hear these messages and thus determine the querier and the non-querier. Suppose for some reason that it doesn't (say, the wrong packets are lost or the switch, not knowing that the router exists, doesn't forward the Query messages). Then the non-querier will not receive queries, will not know the other router exists, and will start sending out General Query messages in due course. The same applies if it receives the initial Query from the other router and never sends any queries out at startup. So the switch should find both routers for sure; even if the start-up is fouled up; it should heal itself. Note, BTW, that draft-ietf-magma-snoop-12.txt and the MRD draft draft-ietf-magma-mrdisc-07.txt (which is going to Proposed Standard IIRC) sets up a new mechanism, Multicast Router Discovery, just to avoid these sorts of problems. Regards Marshall Eubanks On 10/25/05, Shenoy, Vivekananda (Vivek) <vshenoy@riverstonenet.com> wrote: > > Hi, > > My topology is below > > +---------+ > |ROUTER1 | | > | |IGMP | > | ---------| > | | | > | | | > +---------+ | +---------+ > | | | > | | | > | |SNOOPING | > |--------| | > | |SWITCH | > | | | > | +---------+ > | > +----------+ | > | | | > | | | > |ROUTER2 --------| > | |IGMP | > | | | > +----------+ > > A scenario where I have 2 IGMP routers on a single LAN, we know that one > of them will be a querier since only he can send IGMP queries say > Router1 in my case. > > My doubt is how snooping switch will know about the Router2 who is the > non-querier since switch is not receiving any queries from Router2.I > have seen snooping switch maintaining 2 tables 1)Querier table (ROUTER1 > in this case) 2)Router table (ROUTER2 in this case). > > This scenario may exist where Router1 may act as the IGMP querier and > Router2 may be the destination DR who is forwarding the traffic on to > the LAN > > PIM or any multicast routing protocol is not enabled on the IGMP > interfaces so switch cannot see these hellos. > > Thanks > Vivek > > > _______________________________________________ > magma mailing list > magma@ietf.org > https://www1.ietf.org/mailman/listinfo/magma > _______________________________________________ magma mailing list magma@ietf.org https://www1.ietf.org/mailman/listinfo/magma
- [magma] igmp snooping Shenoy, Vivekananda (Vivek)
- Re: [magma] igmp snooping Marshall Eubanks
- Re: [magma] igmp snooping Rajasekaran R
- Re: [magma] igmp snooping Rajasekaran R