Ah I see :) guess I didn't remember that one correctly So it must have both been PIM responsibilities in IGMPver1 and since IGMPver2 - PIM is responsible for Designated Forwarder election and IGMP for Querier election
adam -----Original Message----- From: Phil Mayers [mailto:[email protected]] Sent: Tuesday, September 04, 2012 1:19 PM To: Adam Vitkovsky Cc: [email protected] Subject: Re: [c-nsp] MSDP and my limited knowledge question On 04/09/12 12:00, Adam Vitkovsky wrote: > What I meant when I said IGMP register messages was actually IGMP > membership report message (commonly known as IGMP joins) Yeah, I guessed that ;o) > Also to clarify > IGMP querier is the router elected by PIM(igmp ver2/3) as a router > that sends IGMP queries for the local subnet PIM designated forwarder > is elected by PIM as a router responsible for forwarding m-cast > traffic down/from the local subnet > Since IGMPver2 PIM process is responsible for election of both > function -so they always reside on the same router Are you sure about this? In our environment, which is dual-routed HSRP, we usually see the PIM DF be the *opposite* router to the IGMP querier, because the election rules are different (PIM DF - higher IP; IGMP querier - lower IP) and we're too lazy to add yet another line to the SVI configs to set PIM/IGMP priority. For example: # sh ip igmp vrf PROD int vl76 Vlan76 is up, line protocol is up Internet address is x.x.x.254/24 IGMP is enabled on interface Multicast Routing table PROD Current IGMP host version is 2 Current IGMP router version is 2 ... Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is x.x.x.254 (this system) IGMP querying router is x.x.x.253 # sh ip pim vrf PROD int vl76 det Vlan76 is up, line protocol is up Internet address is x.x.x.254/24 Multicast switching: fast Multicast packets in/out: 0/15871 Multicast TTL threshold: 0 PIM: enabled PIM version: 2, mode: sparse PIM DR: x.x.x.2541 (this system) It doesn't seem to cause any problems, so we don't worry about it. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
