[Xorp-users] IGMP report group ...?

Bruce M Simpson bms at incunabulum.net
Mon Oct 6 08:46:29 PDT 2008


Hervé Léonard wrote:
> Hi,
>
> I try to join a group multicast by sending a IGMP report message from a
> Linux host to a Linux Xorp router (both on a Linux 2.6 - Ubuntu 8.04 Hardy
> Heron)
> ...
> Host A tries to join the group 239.7.7.7 or 224.7.7.7 by sending IGMP report
> v2 on the LAN. Xorp Router B do nothing...?
>   
..

It looks like your XORP router has not received any IGMPv2 JOIN messages.

Please do the following:

1. Check that your network card driver supports "multicast promiscuous" 
mode (aka ALLMULTI).
   ifconfig should tell you if this bit is set.

2. Check that your router is receiving the IGMPv2 JOIN messages on the 
correct MAC address, by passing the -e switch to tcpdump. For IGMPv2, 
this should be the same as the group's MAC address itself.

We need to be sure that the IGMP messages are in fact being accepted by 
the socket layer, and going to the xorp_fea process. Most likely the 
problem is further down in the stack though, I've had problems with the 
FreeBSD fxp(4) driver recently.

thanks
BMS



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