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Webcast-Catalyst9k
Silver

multicast

hello

i have 2 Bluecoat servers (connected to the same switch) that exchange multicast traffic.

i think that by default the switch sends multicast traffic to all ports

what is the best practice to optimize this traffic?

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: multicast

Hello Ohassiri,

each switch will intercept the IGMP report of the locally connected server and should propagate it on the trunk towards the multicast router/IGMP snooping querier.

So yes it should work on this scenario

Hope to help

Giuseppe

3 REPLIES
Hall of Fame Super Silver

Re: multicast

Hello Ohassairi,

>> i think that by default the switch sends multicast traffic to all ports

Actually ig IGMP snooping is enabled and no multicast router is connected to the vlan the switch may block this multicast traffic in an attempt to optimize traffic forwarding.

If a multicast capable router is connected to the vlan and regularly sends out IGMP queries you are fine IGMP snooping will work well moving this multicast traffic only between really interested receivers (your servers).

if no multicast router is connected to the vlan/subnet you should verify if your switch supports a feature called IGMP snooping querier that will send out the regular IGMP queries in order to make IGMP snooping to work correctly.

Otherwise you will need to disable IGMP snooping on that specific vlan (if no multicast router is connected and no switch in use can act as IGMP snooping querier) this will cause multicast traffic to be flooded on the vlan like broadcast.

Hope to help

Giuseppe

Silver

Re: multicast

thank you giuslar for your explanation

what if my servers are connected to 2 differents switches and there is a trunk between these 2 switches? will IGMP snooping work also ?

Hall of Fame Super Silver

Re: multicast

Hello Ohassiri,

each switch will intercept the IGMP report of the locally connected server and should propagate it on the trunk towards the multicast router/IGMP snooping querier.

So yes it should work on this scenario

Hope to help

Giuseppe

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