Catalyst 3548 and Multicast

[bfledderjohn]

I have a flat network and am trying to get Push to Talk working on 2 Polycom phones.  Both phones are on the same vlan.  How do I enable multicast on the 3548?  I would think it would be enabled by default.  224.0.1.116 is the muticast address that the phones use.  I am getting the feeling that the 3548 switch doesn't support multicast.  I have cgmp enabled on the switch already.  Any ideas??

[Ian Jay]

Multicast in the same vlan doesnt need any additional protocol to work. The only reason to enable CGMP is to constrain the multicast, and you will need an Mrouter that supports CGMP to use CGMP correctly.

Disable CGMP on the ports and make sure you have IGMP Snooping disabled. I believe 3548XL doesnt support IGMP Snooping, so this shouldnt be a problem.

Following has some good information on this:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008059a9df.shtml