pim bidir - multicast over WAN

[jeffreywatson]

We have three routers A ,B , C  in a hub and spoke fashion and which peer over a WAN.

The links run pim biidr and most all the time Router A forwards multicast at close to 100M over the WAN to C where the receiver is.

The Service provider polices both circuits so that we cannot use over 100M combined over both links.

When the interface from C-> A goes down then B starts forwarding to A.

I've enabled ip bfd pim - and A sees the C neighbor go down as soon as I shut the C interface to A.

however C continues to forward to the WAN for around 2-3 minutes which over subscribes the WAN.

That continues until the path to C gets removed from the OIL in the Mroute which is 2-3 minutes. 

I'm thinking that's because it's not getting a prune and so the prune timer has to expire. 

Shouldn't the OIL get updated as soon as the pim neighbor goes down?

is there anyway to get C to stop sending as soon as it sees the neighbor go down ?

[Peter Paluch]

Jeffrey,

Can you please provide us with more details about the WAN?

1. What kind of WAN service are you using? Is it Frame Relay, or Carrier Ethernet, or MPLS, or...?
2. You say it is a hub-and-spoke connectivity. However, does it mean that the routers A, B, and C are still in the same IP network across the WAN?
3. Where are the multicast sources and where are the multicast recivers? Is it truly anyone to anyone?

Thanks!

Best regards,
Peter

[jeffreywatson]

Let me make this simpler because I think my scenario is not exactly accurate.

Multicast is sourced to RTR A which peers to RTR B over a WAN.  The receiver is on RTRB.

PIM Bidir is configured and the RP is on A.  Both Routers are connected to L2 switches  and then to the WAN which is a L2 tunnel, so the connection between A and B is point to point.   We run BFD for both EIGRP and PIM.

So RTR A forwards to B - when the link goes down BFD takes care of adjusting the unicast routing table and the PIM neighbor goes down immediately.  But the traffic keeps getting forwarded out from (A) to the WAN until the Mroute OIL Timeout expires which can be up to 3.5 Minutes.

Why doesn't PIM BFD immediately update the Mroute OIL when it sees the neighbor go down ?