On Mon, Jan 24, 2011 at 10:58 PM, Aaron Riemer <[email protected]> wrote: > I would get wireshark running on one of the hosts that tries to join a > multicast stream. Set IGMPv3 on the switch and monitor the subsequent IGMP > packets. i.e. Does an IGMPv3 query get sent out and do the hosts reply with > a join? > > I would assume that swapping from IGMPv2 to IGMPv3 would clear out any > snooping information on the switch and thus would need to wait for > subsequent queries / membership reports?
That was my thought, too, but we're going to have to run the test again to verify that. This part of the network has some interesting qualities that are making it difficult to predict how it's supposed to behave. For example, this is a single VLAN with two switches. Each switch has an vlan1 with an IP address configured, but ip routing is disabled on both switches. Interestingly, PIM is enabled on those interfaces and the two switches see each other as PIM neighbors. However, I don't think PIM is actually doing anything because there are no actual routed interfaces involved. Here's where it gets strange. Since there are no interfaces functioning as a router, there is no IGMP querier unless we manually create one. However, it appears that by enabling PIM on the L3 vlan interfaces, a querier was enabled automatically, as well. So it seems that PIMs only function at the moment is to enable the querier, which is enabling snooping to work. We're changing the IGMP version on the L3 vlan interface, but since that isn't acting as a router, at least for unicast, I'm not sure why it even matters. This is all really complicated and difficult to explain without a good diagram. lol But it is strange behavior. I'm tempted to just enable unicast routing so that those vlan interfaces are unequivocally router interfaces. Then I could turn PIM off since it isn't doing anything but turning on the querier. That would make the behavior a bit more predictable. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
