RE: 1st multicast ping succeeds, the rest fail?

Hi JR,

This SHOULD not be a shared-tree/source tree cutover problem, because the
cutover is not supposed to happen if the source tree is broken.

I think you will see that the first echo reply was the result of the unicast
PIM registration process. The first hop router unicasted a source
registration to the RP, the RP decapsulated it and multicast it to the
receiver. The RP sent a unicast registration stop to the first hop router.
The multicast path between the RP and the source is broken, and the RP never
actually received the multicast stream.

To troubleshoot, explore the reverse path from the RP to the source. You
could use show ip rpf, or mtrace. To see this decapsulation in action, clear
ip mroute and enable debug ip pim on the RP.

HTH,

Bob Sinclair

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> JR Garcia
> Sent: Monday, May 31, 2010 7:09 PM
> To: Cisco certification
> Subject: 1st multicast ping succeeds, the rest fail?
>
> ive ran into this on a couple labs ive done. just seeing if anyone has
> an idea.
> Separate MPLS VPN sites learn the RP through the MPLS cloud, i throw
> ip igmp x.x.x.x on an interface, the 1st ping will respond, but any
> pings after that fail.
>
> i cant seem to find any RPF failures. i dont have any configs
> off-hand, but was just curious is anyone else has ran to this before.
>
>
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Received on Tue Jun 01 2010 - 08:39:35 ART