[Xorp-users] getting problem in IGMPv3 XORP behavior

Bruce M Simpson bms at incunabulum.net
Tue Jul 22 07:28:04 PDT 2008


Tushar Mehta wrote:
> here my setup design is attached.
>
> My IGMPv3 router is running and is attached with host via switch.
> IGMPv3 is running on XORP.
> just for checking i am sending a IGMP General Query(without router 
> alert option) from Host machine to XORP router.
> in this case it should not reply by sending IGMPv3 report but it is 
> replying in my case.

Can you paste a Wireshark or tcpdump capture of how the IGMPv3 router is 
responding to the query?

It is entirely possible (and likely) the router is responding to the 
query in line with the protocol if it's a member of any IGMP groups.

For example, state change for end stations in groups within the 
224.0.0.0/8 block need not be announced, however if they aren't, this 
breaks IGMP snooping at the link layer.

You don't specify if your switch performs IGMP snooping.

Rememeber, there may be more than one IGMPv3 querier in an IP subnet -- 
there is an election process when there is more than one querier.

thanks
BMS



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