Chapter9.Multicast

Chapter 9. Multicast

Refer to the following sections to configure and use these features:

• 9-1: IGMP Snooping Explains how to configure a switch to constrain multicast traffic by listening to Internet Group Management Protocol (IGMP) messages.

• 9-2: CGMP Discusses the steps needed to allow a switch and a router to constrain multicast traffic by exchanging Cisco Group Management Protocol (CGMP) messages.

• 9-3: GMRP Covers the configuration steps needed for a switch to use the GARP Multicast Router Protocol (GMRP) to communicate with multicast hosts.

• 9-4: RGMP Explains how a switch and a router can use the Router-port Group Management Protocol (RGMP) to constrain multicast traffic toward routers in the network.

TIP

Choose the multicast features for your network based on the type of switches that are used. IP multicast routing using Protocol Independent Multicast (PIM) is usually required and is configured only on a router or Layer 3 platforms. Configure other multicast features based on the following guidelines and the information in Table 9-1.

• Use IGMP snooping on all but the low-end switch models. IGMP snooping doesn't require any other interaction with routers.

• Use CGMP for the lower-end switch models that can't use IGMP snooping. Be sure to configure CGMP on any directly connected router interfaces so that CGMP information is fed to the switches.

• Use GMRP to control multicast traffic only if your multicast-capable hosts can use both IGMP and GMRP. The switch platform must also be GMRP-capable.

• Use RGMP to prune multicast traffic to routers even further, eliminating ports to routers that don't need multicast groups. Both routers and switches must support RGMP.

Table 9-1. Switch Multicast Features

Catalyst Model	PIM Routing	IGMP Snooping	CGMP	GMRP	RGMP
2900XL	N	N	Y	N	N
3500XL	N	N	Y	N	N
3550	Y	Y	N	N	N
5000	N	Y	Y	Y	Y
4000 Sup I, II	N	Y	Y	Y	N
4000 Sup III	Y	Y	Y	N	N
6000 w/ PFC	N	Y	N	N	N
6000 w/ PFC/MSFC	Y	Y	N	Y (COS)	Y
6000 w/ PFC2/MSFC2	Y	Y	N	Y (COS)	Y