Cisco group management protocol (Routing) (CGMP)

The Cisco Group Management Protocol (CMGP) limits the forwarding of IPmulticast packets to ports to which IP multicast clients are connected. Such clients can automatically join or leave a group that receives IP multicast traffic.

Cisco Group Management supports multiple services, so IP multicast packets can be forwarded only to those ports to which IP multicast clients are also connected, and it can prevent unnecessary multicast traffic and overhead, thus saving bandwidth.

The header of the CGMP protocol mainly consists of the number field, the 6- byte group destination address, the 1-byte message typedata field, the 6-byte unicast source address, and the CGMP version data field.