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Extending Multicast network at Layer 2 for IPTV service

Hi all, this is a bit of an oddball topic but I've been asked to assist one of our remote sites with getting their newly purchased (rebranded) AT&T uVerse service from the demarc to a couple of remote buildings on-site where they want the STBs to reside.

At first, I thought no problem, we'll just carve out a new VLAN and carry the traffic at Layer 2. Seems easy enough (if the traffic was all unicast)...however I discovered there is a multicast dpeendancy; when an STB tunes to a channel, the first 10-15 seconds are sent unicast while the residential gateway prepares the mcast stream. Once the feed switches to mcast, the picture becomes pixelated and drops out frequently.

I suspected IGMP snooping might be the culprit, so I checked each of the switches in the path for IGMP snooping querier, group, and mrouter params; all of the switches are seeing the mcast groups (IGMP v3), each one sees the residential gateway device (2wire 3801) as the IGMP querier, and the mrouter ports are all identified correctly.

The main problem (I suspect) is that the switchport that the STB is connected to is never being added to the IGMP snooping group, as evidenced by the following debug output

--> IGMPSN: group: Skip client info adding - ip, port_id Gi0/5, on vlan 600

From CFN, it looks like support for IGMP v3 varies in capabilities across the Catalyst platforms, and before I put in a call to either the telco or TAC, I wanted to get some feedback in case any of you folks have had similar experiences running/extending IPTV services across an enterprise campus at Layer 2.

For reference, the switching infrastructure involved includes several Catalyst 3560G (and CG compact units) as well as a 3750G stack at the core. All platforms are running (at a minimum) IOS 12.2(55)SE7.

I've followed several of steps identified here with no success so far:

Thanks in advance for any feedback you can provide.

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