Re: IGMP Snooping proxy

Hello Bharat,

Thanks for the answers.

*         Can you please elaborate as to what the igmp router can be configured with; is it to explicitly specify to process reports with src-ip 0.0.0.0?

*         I referred in 2236 (mine is a v2 router) where, I couldn't find a reference for this?

*         Lastly, regarding valid source-ip; I agree that a part of aggregation will be defeated but the switch may send just ONE report per mc group per vlan in addition to the aggregated report. The switch can use the source-ip of the report which it last heard to refresh its group membership expiry timer for than LAN.

*         OR it must be made possible in the proxy-snooping implementation to configure an ip-address per mrouter port which, can be used as the source-ip for the aggregates.



Thanks,

Magesh.



-----Original Message-----
From: Bharat Joshi [mailto:[email protected]]
Sent: Monday, April 13, 2009 8:57 AM
To: V, Magesh (Magesh)
Cc: [email protected]
Subject: RE: IGMP Snooping proxy





Hi Magesh,



    Please see my response in line.



Thanks,

Bharat



>A v2 snooping switch that works in proxy-mode may aggregate and send the v2 igmp membership reports to upstream igmp

>router with source ip address 0.0.0.0. In such a case,

>

>1. How can the upstream igmp router ensure that the membership report is coming from a host that is indeed in the same

>subnet that of the igmp interface?



It can not. Router needs to be told that there is a snooping switch which does aggregation as well.



>2. Should the igmp router not discard the reports if the source-ip of such packets are not in its local network?



No. It should not. A router needs to be configured appropriately to not discard such messages. IIRC, Proxy RFC mention this somewhere.



>3. If such packets (as in 2) will indeed be dropped then is it not required of the snooping switch (proxy mode) to

>send at least one report for each LAN w/ valid source-ip address for that network?



As I mentioned above, router must be configured not to drop these packets.



For your question, if snooping switch forwards at least one report upstream for each valid source ip, part of aggregation is broken. Another question is how does this switch will know what all are the valid source addresses?



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