How to configure Multicast on the switch

IP multicast allows a host to send packets to a subset of all hosts (group transmission). These hosts are known as group members.

Routers executing a multicast routing protocol, such as Protocol Independent Multicast (PIM), maintain forwarding tables to forward multicast datagrams. Routers use the Internet Group Management Protocol (IGMP) to learn whether members of a group are present on their directly attached subnets. Hosts join multicast groups by sending IGMP report messages.

The basic steps to configure IP multicast routing

Step 1: Enable ip multicast routing

 SW(config)# ip multicast-routing


Step 2: Enable PIM on an Interface

 SW(config-if)# ip pim sparse-mode
 or
 SW(config-if)# ip pim dense-mode 


Step  3: Configuring RP
If you configure PIM to operate in sparse mode, you must also choose one or more routers to be rendezvous points (RPs). You need not configure the routers to be RPs; they learn how to become RPs themselves.

There are types RPs: non auto and auto

Configure a non-auto RP
 ip pim rp-address rp-address

Configure a auto RP:
 announcing the RP and the group range it serves:
 ip pim send-rp-announce type number scope ttl-value [group-list access-list] [interval seconds]

assigning the RP mapping agent:
 ip pim send-rp-discovery scope ttl-value 

Note: 
 If you configure PIM in sparse mode or sparse-dense mode and do not configure Auto-RP, you must statically configure an non-auto RP

Sometimes:
 Use the ip pim autorp listener command with interfaces configured for PIM sparse mode operation in order to establish a network configuration where Auto-RP operates in PIM dense mode and multicast traffic can operate in sparse mode, bidirectional mode, or source specific multicast (SSM) mode

Examples 

The following example enables IP multicast routing and the Auto-RP listener feature on a router. It also configures the router as a Candidate RP for the multicast groups 239.254.2.0 through 239.254.2.255.

ip multicast-routing

ip pim autorp listener

ip pim send-rp-announce Loopback0 scope 16 group-list 1

ip pim send-rp-discovery Loopback1 scope 16

access-list 1 permit 239.254.2.0 0.0.0.255

IP is particularly suited for multimedia applications that involve multiple participants. Issue the following show commands from the CLI to verify multicast configurations on your devices:

Switch# show ip pim rp
Switch# show ip mroute

Configuring IP Multicast Routing: www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfmulti.html#wp1000948

http://www.cisco.com/c/en/us/td/docs/ios/12_2/ipmulti/command/reference/fiprmc_r/1rfmult2.html#wp1090395