While configuring Multicast Routing especially in Cisco based network devices, IGMP and CGMP are frequent terms the administrators and implementers come across. The overlapping functionality of both terminologies tends to increase the confusion on what to configure on which device. So here we will brief about both the technical terminologies features and then understand there difference –
IGMP is used to dynamically register individual hosts in a multicast group on a particular LAN. Hosts identify group memberships by sending IGMP messages to their local multicast router.IGMP has 3 version –
CGMP is a Cisco-developed protocol that allows Catalyst switches to leverage IGMP information on Cisco routers to make Layer 2 forwarding decisions. CGMP must be configured on multicast routers and the Layer 2 switches .With CGMP, IP multicast traffic is delivered only to those Cisco Catalyst switch ports that are attached to interested receivers.
The comparison between IGMP and CGMP is enlisted in below table –