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CGMP used by Cisco LAN switches

While I was searching I found this on net: it was answer to one of the CCIE question:

CGMP is the Cisco Group Management Protocol (CGMP) which is multicast protocol used by Cisco LAN switched , and nor routers.

Is this right ?

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Anonymous
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Re: CGMP used by Cisco LAN switches

Community Member

Re: CGMP used by Cisco LAN switches

cgmp is an alternative to igmp-snooping.

The essence of this by a switch is to bind the interested propriate multicast group to the appropriate switchport.

cgmp needs assistance by the router and hence it runs both on the switch and the router.

for eg. when a host sends an igmp report to the router requesting it to be added to the multicast group as a client, the cgmp enabled router sends a cgmp join message to the switch with the mac-address of the igmp report sender and the multicast group that was requested for in the igmp report msg.

Hence CGMP is required for multicast at layer2 and assisted by the router.

At the router, cgmp needs to be enabled at the interface level.

And, cgmp and igmp-snooping are mutually exclusive.

hope this helps

cheers

Arav

Community Member

Re: CGMP used by Cisco LAN switches

Thanks Arav for this explaination.

What about the question? can we consider it right ?

Community Member

Re: CGMP used by Cisco LAN switches

As you know if have to enable CGMP om switch and router, that means (for my understanding) we have used it on both devices, not only one,,,Am I right ?

Community Member

Re: CGMP used by Cisco LAN switches

Yes, the answer can be considered right.

Cheers

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