IP multicat communication

Unanswered Question
Mar 31st, 2009


My server( has to communicate to my client( over multicat address udp port 8192.I have enable ip multicat on all the interface on the path as below,

""ip multicast- routing"

on int

"ip pim spare-dense-mode"

There is no Firewall in the way but communication is failing by giving "socket error" on client.

Is any way I can trace or troubleshoot this issue?


I have this problem too.
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shivlu jain Tue, 03/31/2009 - 08:39

could you send the topology diagram. If multicast runs on two paths then may be the RPF could fail. But first need to check the design. Please post it.


shivlu jain

Giuseppe Larosa Tue, 03/31/2009 - 09:44

Hello Mohammed,

use sh ip rpf source-address

to check if the traffic arrives from the RPF neighbor

Hope to help


mohammedrafiq Tue, 03/31/2009 - 09:53

6509#sh ip rpf

RPF information for ? (

RPF interface: Vlan124

RPF neighbor: ? ( - directly connected

RPF route/mask:

RPF type: unicast (connected)

RPF recursion count: 0

Doing distance-preferred lookups across tables

Giuseppe Larosa Wed, 04/01/2009 - 02:25

Hello Mohammed,

this is from the switch that is connected to the source.

RPF type: unicast (connected)

You should check using the same command on the other devices those near the receiver.

In this way you can detect if there is an RPF issue caused by the topology.

Hope to help



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