Stupid IGMP issues...

Hi! This is probably a superstupid issue, but after 5 hours troubleshooting i thought i might ask for a hand here :)

I'm having a bit of trouble setting up my IPTV in my home, using my own cisco-equipment instead of my ISP issued equipment. Now my setup is as follows : ISP Router (bridged mode) --> Cisco ISR1111 --> Cisco C2960 ---> IPTV decoder.

The ISP Router is bridged, but probably doing some vlan-tagging to separate internet from IPTV-traffic, so LAN port 1-2 is for IPTV and port 3 is for internet. I have connected port 1 (IPTV) into one of the Layer2 switchports(port0/1/2) in my ISR and tagged it with VLAN 20, then i'm trunking vlan 20 to my 2960 switch (port gi0/1/7 on ISR to port gi0/1 on 2960) and i have my IPTV decoder connected to port gi0/4, as an access-port in vlan 20. The ISP router is giving DHCP on the IPTV-ports.

I can get TV-signals just fine, and i have IGMP Snooping enabled on both devices. But after 120 seconds IGMP on the ISR sends a leave-message to my trunk and my TV goes black, naturally.. This is due to a report-timer expired message, and i cannot seem to figure out whats causing this. The switch does not seem to pass any reports to my ISR that it has active members of my IPTV streams..

If i disable IGMP Snooping on the ISR then everything is working as it should.. I have enabled debug ip igmp snooping on both devices and i see the following on the ISR:

Dec 23 16:24:06.863: IGMPSN: Received IGMPv2 message for group 0.0.0.0 received on Vlan 20, port Gi0/1/2Dec 23 16:24:06.863: IGMPSN-2: IGMPv2 General Query received on Vlan 20, port Gi0/1/2 Resp time 10000 (100 100) msecs, LLQ time 2000 (2 1000) msecsDec 23 16:24:06.863: IGMPSN-2: IGMP general queries received on Vlan 20 updates all groupsDec 23 16:24:06.863: IGMPSN-2: timer: start report_timer 10000 msecs of vlan 20Dec 23 16:24:06.863: IGMPQR: vlan 20: GQ with src addr 192.168.10.1 received on port Gi0/1/2 in Disabled stateDec 23 16:24:06.863: IGMPSN: router: Received IGMP pak on Vlan 20, port Gi0/1/2Dec 23 16:24:06.863: IGMPSN-2: router: port Gi0/1/2 is a router port on Vlan 20Dec 23 16:24:06.863: IGMPSN-2: router: Learning port: Gi0/1/2 as rport on Vlan 20Dec 23 16:24:06.863: (l2mcsn_flood_l2mc_pak) IGMPSN-2 flood pak to vlan 20Dec 23 16:24:16.861: IGMPSN-2: timer: report timer expired on Vlan 20Dec 23 16:24:16.861: IGMPSN-2: sync group for Vlan 20 robustness variable 2

but none of this information is shown on my C2960, so it seems as none of the queries pass down to the 2960? Is there something blocking multicast traffic from trunks?..

If i switch channels on my IPTV then i get picture and everything is working fine, until the 120 second timer expires and i have to switch channel back and forth to make it work again..

I have set the mrouter on both devices uplink ports, tried setting querier on both the ISR and the switch but nothing seems to help except for disabling IGMP on the ISR and letting it behave as broadcast traffic.

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I am new to all IGMP stuff, so if you guys have any idea of whats happening i would be very happy for some help :)

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edit: just clarifying that my ISP is plugged to a L2 port on the ISR and not doing any routing.