I'm trying to understand how an IGMP router gets started. It _seems_ to me that there's a state transition missing in RFC 2236 (or maybe it's implied and I haven't figured that out yet).
Consider this network:
+---------+ | Server | +---------+ | --+---+-----------+---- N1 | | +--------+ +----------+ | Host 1 | | Router 1 | +--------+ +----------+ | ---+-----------+------ N2 | +----------+ | Router 2 | +----------+ | | +--------+ +--------+ | Host 2 | | Host 3 | +--------+ +--------+With Host 1 a member of a multicast group served by Server, Router 2 powered off, and Host 2 and Host 3 wanting to be part of the multicast group but unable to reach Router 1 or Server. Router 1 has a lower IP address than Router 2 and will remain the Querier on N2 even after Router 2 is fully initialized.
As I understand it, when Router 2 powers up, it'll send a General Query on all it's interfaces. Router 1 should ignore that because Router 2's IP address is higher. Host 2 and Host 3 should respond with Reports (after suitable, random delays). Now Router 2 knows Host
2 and Host 3 are there and want to be members of the group but Router 1 hasn't seen the Reports so it doesn't route the multicast data to Router 2 to forward.Eventually, Router 1 times out and sends a General Query which Router
2 sees. If Router 2 sends a proxy Report for the group Host 2 and Host 3 want to be in, things get goind OK after this but I don't see anything in RFC 2236 that says such a proxy Report is sent. (I've been through is many, many times and I'm kind of bleary eyed so maybe I'm missing it.)I can see a couple of ways to speed up convergence of this network but neither seems to be prescribed by RFC 2236.
First, if Router 2 floods the first Report to all ports but the one it was received on, Router 1 would see an Unsolicited Report and could add that group to its routing table. (And the other one of Host 2 and Host 3 would stop their timer and not send a Report at all.) Is that flood part of "notify routing +"?
Second, if Router 1 sends a General Query of its own when the link to N2 becomes active, Router 2 would be aware that there's another router out there and that could lead to some magic that converged the network.
I'm sure I've skipped over something. IGMP works, right? ;-) Any pointers to my failing would be appreciated. Thanks.
Chris