one way multicast issue

Unanswered Question
Jul 29th, 2008
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I'm troubleshooting one way muticast problem and when i do show ip igmp groups it show stopped on one router, can someone tell me what could be the problem?

sh ip igmp groups

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter Serial0/0 7w0d stopped

also to add when I do show ip mroute

I one router shows RPF neighor but the other shows


(,, 00:01:13/00:01:46, flags: PT

Incoming interface: Serial0/0, RPF nbr

Outgoing interface list:

FastEthernet0/0.3, Prune/Sparse-Dense, 00:01:13/00:01:46


(,, 00:00:30/00:02:29, flags: PCT

Incoming interface: FastEthernet0/0.3, RPF nbr

Outgoing interface list:

Serial0/0, Prune/Sparse-Dense, 00:00:30/00:02:30

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Giuseppe Larosa Tue, 07/29/2008 - 08:30
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Hello Hawaz, is a well known multicast address used by Auto-RP feature but you are using sparse-dense mode so it doesn't matter

Let's look at group (, this should be your user traffic.

You are using PIM sparse-dense mode on your interfaces.

The traffic flow should arrive at router RB state is pruned P=pruned C=connected T should be best path tree.

RB should have the source on fas0/0.3 because RPF neigh is

From router RB traffic would go to RA via serial interface

Serial0/0, Prune/Sparse-Dense, 00:00:30/00:02:30

For RA incoming interface is serial 0/0 RPF neigh is (this should be RB serial int ip address)

outgoing interface is FastEthernet0/0.3,

the pruned state is timed but until a receiver does not join group on an interface downstream RA it will stay so !

You need an interface on RA where you put ip igmp join-group

Notice if RA and RB f0/0.3 are directly connected and are in the same IP subnet multicasting does not need to be routed so you will have the pruned state even if you receive multicast traffic.

Hope to help



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