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Multicast filtering better at L-2 or L3 ?


Anyone have experience with multicast filtering features as

IP IGMP Filter   or   IP IGMP Max-groups features in a layer-2 switching environment or

in a layer-3 environment   IP IGMP ACL   or   IP IGMP Limit features on a router?

Is it better to filter on ingress user ports on a layer-2 switch or utilize layer-3 filtering techniques on the router or BOTH?

Is some other method better?

Our switches are 2960, 3750 and 4500 series.

What we're doing - I'm starting to roll out multicast (PIM Sparse-mode only, for now) across the MPLS WAN (~300 sites) using redundant auto-RPs via Anycast and group dissemination between mapping agents via MSDP.  Multicast groups will consist of a /28 group range ( so our multicast setup will be considered small. Each LAN environment is configured to use IGMPv3 on VLC clients. Since this may well end up being a 1 man show, I would like to take as many up front precautions as I can -  perhaps ease up on the restrictions later on.

So far I have noticed many local devices continue to solicit for their group addresses I.E. HP at, MS SSDP at, Novell SLP at etc. etc. etc. I don't want surprises to complicate this implementation. I cannot force the support staff to correct these issues so I have to work around 'em - with filtering I guess!!!

THANKS for sharing



IP IGMP filter

IP IGMP Max-groups


IP IGMP Access-Group (standard or extended)




Update....... just in case you cared :

The filtering techniques above appears to be only supported by IGMP version 2, which is fine. VLC operates with IGMP version 2 also. However Layer-2 filtering seems to be crap. Many issues.

Only tested on the Cisco 2960 switch as this model of switch is most prevalent within our environment.

IGMP filtering at layer 3 however is much easier and things respond immediately. Limiting the number of groups works as expected. Filtering via ACL works very well too. Response is immediate



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