I'm currently having issues sending multicast across a GRE tunnel. I attached a crude drawing to kinda of help depict what I'm talking about...Here is a quick run down of what we are seeing..

- both routers have the correct pim neighborship

- multicast traffic originating from the 192.168.1.0 network is being transmitted over to the 172.16.100.0 network. We verified this with show ip mroute active on both routers. We can also see it in show ip mroute 236.5.5.1. The problem is the clients on the 172 network don't actually recieve the multicast.

- multicast traffic originating from the 172 network is not being routed over to the 192 network. We dont see any active mroutes on either routers. We do see the traffic being originated, and the router on the 172 network recieving the multicast, but it drops the packets. We see this in the sho ip mroute 236.5.5.1 count. The results show all packets being dropped by "other" reasons (OIF-null, rate-limit. etc.). Also, when debugging the ip mroute 236.5.5.1 we can see that the packets are being routed to the "null" route list.

- lastly, the router on the 192 network shows mroutes from the 172 network as incoming on the physical interface (e.g. G1/0) not the GRE tunnel. The router on the 172 network does show the mroutes incoming on the GRE.

I don't have access to the debug logs to post them but that's pretty much it. If there is any more information I can provide please let me know.

v/r