2524 & IGMP question

[Stuart Teo]

If I issued an 'ip igmp block' command to a port, does it block only inbound or does it also block outbound multicast traffic?

[Jerome Henry]

Hi,

Bloacking igmp will prevent multicast traffic to be flooded thru that port, in outbound way. But the decision to flood is made after port has transmitted to the ship, that is to say, in most cases (except specific multicat address structure), inbound won't be blocked.
Good idea is to apply this command to all ports, especially the pruning ones.

hth

J

[Stuart Teo]

I couldn't do that. (block all ports)

The devices on all the port (except the uplink port) need to be able to see the multicast group. However, I do not want those traffic to be transmitted out of the uplink port.

I thought that by blocking the uplink port would do the trick but I'm still seeing subscribes at my routers. Sigh.

[Stuart Teo]

hp support stated that the block command should block both incoming and outgoing multicast groups excluding some specific groups like all routers, bpdu, etc.