All things related to multicast

[Stig Venaas <>]

Bob Riddle wrote:
> The problem I experienced when WinXP only supported IGMPv3 involved an 
> edge router that supported IGMPv3 and a switch that did not support 
> IGMPv3.  This allowed the WinXP machine to "join" the multicast stream 
> but the switch threw away all the "keep-alive" messages from the 
> router.  As long as you only needed to watch a few minutes of the 
> multicast stream, everything worked fine   :-) .

Right, I've also seen this happen. I must confess that whenever I hear
of an IGMP related problem I think of the switches as the most likely
culprit. I know of cases where there have been as many as 5 switches
between the router and the host. It didn't take too long to find out
that the regular IGMP queries from the router never reached the host,
but it's quite tedious to find out which of the 5 switches discard it.

> When I set up a linux machine using IGMPv2 to listen to the stream on 
> that switch, it "kept alive" the stream.   Lots of weird debugging 
> involved, so good luck!

Second that :)

Stig