multicast routing problem

Unanswered Question
Jan 21st, 2009

Hi.

I have a multicast "client" sending a join request to a multicast group on vlan 11.

The multicast source sending the multicast is on vlan 120.

I use a L-3 switch Catalyst 3550 using PIM-DENSE mode configure on these two vlan interfaces.

the join request does NOT stop at the routing engine on the switch and is being forwarded to vlan 120 as flooding.

multicast traffic does NOT reaching the client unless I push the multicast traffic to the interface of the client.

It looks that the L-3 switch does not recognize the structure of the join message.

IGMP Snooping is configured.

Any idea what can be done to make the multicast work "normally"?

Thanks.

I have this problem too.
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Giuseppe Larosa Wed, 01/21/2009 - 09:23

Hello Danny,

I would try to disable igmp snooping to do a test.

IGMP should not be forwarded from one interface to the others because they are sent to 224.0.0.2 all routers in subnet that is link local scope.

Verify also the igmp version used by host and c3550 there can be a mismatch.

if you like you can post

sh ip igmp group

sh ip mroute

Hope to help

Giuseppe

danny4569 Sun, 01/25/2009 - 04:27

Hi Giuseppe

Thank you for your help.

It looks that the problem was that the multicast group ip address was correct but the destination MAC address from some reaon was a broadcast mac address.

after fixing the mac it looks that the traffic is working fine.

Again, thank you.

Danny.

glenthms Wed, 03/04/2009 - 07:15

Danny? Can you update how you found the solution to your problem as stated? What did you do to determine the fix?

danny4569 Sun, 01/25/2009 - 04:28

Hi Giuseppe

Thank you for your help.

It looks that the problem was that the multicast group ip address was correct but the destination MAC address from some reaon was a broadcast mac address.

after fixing the mac it looks that the traffic is working fine.

Again, thank you.

Danny.

Giuseppe Larosa Sun, 01/25/2009 - 04:59

Hello Danny,

nice to hear that you solved in your case the issue was on the multicast application not using the right multicast address to encapsulate packets.

Not all network problems are caused by network devices...

Hope to help

Giuseppe

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