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New Member

Blocking Multicast on Layer 2 switch

Cisco 2960, layer 2.


trying to block inbound multicast from a single switchport.  My CUCM to be exact.


IGMP will not do what I need as I have phones trying to listen to Multicast MOH from the server, and Im trying to block it.  Phones and server are on the same subnet.  I do not want the MC packets to hit the phones as they need to listen to something else on the same IP


ACL on the port didnt work, neither did switch block multi as I think it doesn't block packets with a correct source mac.


Storm-control multi level 0 didnt work, neither does storm-control broad level 0


Any other options?  Or are one of these options actually working and I just dont know it (my multicast isn't setup right lets say).  I see my multicast counters on the port go up when I turn on multicast from the server so I know its being sent.


Hi ,You can block layer 2

Hi ,

You can block layer 2 Multicast traffic with following commands


Step 3 

switchport block multicast

Block unknown multicast forwarding out of the port.

Note Only pure Layer 2 multicast traffic is blocked. Multicast packets that contain IPv4 or IPv6 information in the header are not blocked.




New Member

This doesn't seem to work for

This doesn't seem to work for my situation, as I believe there is ipv4 headers in the packets still.  At least I tried it to no avail. 


New Member

Why not try to disable MOH or

Why not try to disable MOH or move the servers onto a different VLAN, This way you are breaking up into two broadcast domains.




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