9-2. CGMP
CGMP is a cooperative protocol between Cisco routers and switches used to constrain multicast traffic.
CGMP on a Catalyst switch relies on a CGMP router to provide it with multicast join or leave requests. This allows efficient multicast group registration without requiring the switch to inspect IGMP messages.
CGMP uses destination multicast MAC address 01-00-0c-dd-dd-dd for all its messages. These messages are flooded to all switch ports so that even non-CGMP switches will relay CGMP information.
CGMP requires that IGMP snooping be disabled. The two features are mutually exclusive. However, a router can be configured for both IGMP and CGMP to support a variety of switch platforms.
CGMP is supported on all Catalyst switch platforms except ...
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