Cisco Group Management Protocol
Cisco Group Management Protocol ( CGMP ) is a proprietary network protocol which was developed by Cisco Systems and is also used exclusively in Cisco products. It has the same function as the IGMP protocol, but is proprietary and is used to organize multicast groups. It works at the level between the host and the router .
use
It is used for multicast transmissions and automatically detects which clients are joining the group, thus dynamically changing the routing.
The protocol has the following properties:
- Packets are only by the required ports of the switch is sent
- does not need any special configuration at the host
- protects the network load by sending the packets in a targeted manner.
Technical
A CGMP frame is an Ethernet frame that has the destination MAC address 01-00-0c-dd-dd-dd and a SNAP header with the number 0x2001, which contains the following fields:
- Action (enter or leave group)
- Version (1 or 2)
- The number of addresses
- Destination MAC address ( multicast address)
- Origin MAC address ( unicast address)