PIM/Register for multicast sources not directly connected

[Gianstefano Monni]

Dear all,

we have a topology where the Multicast traffic is originated from a network which is not directly connected to the PIM DR (the sources are located on a network which is routed through the ISP Router). In this scenario we see that the DR is not sending the PIM Register to the RP.

RP <--> DR <--> IPTV-GW <--Multicast Sources

The IPTV-GW is directly connected to the multicast sources and it is forwarding the multicast traffic (UDP) but it doesn't play any role in the PIM Signaling (it is not a PIM neighbour, and sparse-mode is not configured on this router).

On the DR we see all the (S,G) for the sources "behind" the IPTV-GW, with the correct RPF, but the DR itself does not send any PIM register messages for this sources. It sends PIM Register only if the sources are directly connected to the DR (through SVI or Layer3 interfaces)

Is this by design or this behaviour can be configured?

Thank you for your help, with best regards

stefano

[johnd2310]

Hi,

You need to enable multicast throughout the network(s) that will participate in multicast. Ensure that pim is configure on all router interface from source to destination and all routers should have an RP. If your ISP cannot support multicast into your network, then you should look at tunneling the multicast over a gre tunnel 

Thanks

John

[Gianstefano Monni]

As workaround we fixed the issue by assigning a secondary IP address on the same range of the remote network, at that point the DR started sending the REgister message to the RP.