Multicast "router alert" problem on cisco L-3 switches

Unanswered Question
Nov 26th, 2007


I have a problem on IBM UNIX servers (NO problem on Microsoft OS).

The UNIX does not send in the IGMP report the "router alert" option (the UNIX can NOT be upgrade)after the first IGMP join to a multicast group.

after 4 minutes the UNIX loses the multicast group.

I am looking for a way to keep the membership of the UNIX to the specific Multicast group even though no "router alert" option is being send to the L-3 switch.

Any idea???


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owillins Mon, 12/03/2007 - 08:44

For your requirements you should upgrade host stack to IGMP version 2 or IGMP version 3 .

nyurk Mon, 12/03/2007 - 14:28

Alternatively you can use "ip igmp snooping querier" on a router interface connected to the VLAN if you do not want to goto IGMP v2 or 3.

Nick Wed, 01/13/2010 - 08:06


i have a problem whith the IGMPv2 Query from my C3750.

This Query comes without IP option "router alert".

How do i activate this?

Thank you.


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