Multicast on Catalyst 3560 24 Port...

Unanswered Question
Sep 26th, 2008

Hi - I am trying to do a multicast (not video/audio, but text) using the Catalyst 24 port 3560 switch - looks like the ports gets flooded and all the lights on the switch keep blinking. I am using a third party software to build a grid federation on the systems connected to the switch. any ideas? basic question is that does 3560 support UDP multicast...??? the grid infrastructure comes up for a few minutes and then goes down...

I have this problem too.
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muralidhar1967 Fri, 09/26/2008 - 23:23

Hi - yes, I also suspect flooding; I havent configured anything on the router; do I also need to enable multicasting or is it enabled by default? The machines are directly connected to the switch and form a grid infrastructure that pumps in data through UDP/multicast ports (specific ports) and there is a listener that picks up the data and puts it back into the grid. would this work? regards Murali; if possible you could call me at 9845 319 886

Jon Marshall Sat, 09/27/2008 - 03:43

As per the link previoulsy provided you need to do 1 of 2 things.

1) If the traffic is only staying within the same vlan and does not need routing then

i) enable IGMP snooping

ii) enable IGMP querier functionality on the 3560. Without the querier function the traffic will still be flooded to all ports

2) If the traffic needs routing enable pim (either sparse or dense mode) on the relevant L3 interfaces. When you enable pim you automatically enable the IGMP querier function so you don't need step ii) from the above.


Jon Marshall Sat, 09/27/2008 - 04:42

Apologies - for option 2 you also need to enable mulitcast routing ie.

3560(config)# ip multicast-routing


muralidhar1967 Sat, 09/27/2008 - 04:47


thanks, I will make the changes on Monday and give you my feedback on this issue.

best regards - murali


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