System information

Configuring IP Multicast Routing
8-3
The BSR supports PIM in sparse mode. In sparse mode, routers must join and leave
multicast groups explicitly. Upstream routers do not forward multicast traffic out a
PIM interface unless the router has sent an explicit request called a join message to
receive multicast traffic from a downstream router or if group members are directly
connected to the interface. When a host joins a multicast group, its first hop router
sends a join message upstream to the rendezvous point (RP) for the group. The RP
serves as the root of the shared multicast delivery tree and is responsible for
forwarding multicast data from different sources toward the receivers. PIM
sparse-mode routers periodically send join messages toward the RP to join a shared
tree and directly toward the source if they prefer to join the source tree. The routers
also send periodic prune messages to the RP when they move from the shared tree
onto the source-based tree. At least one Bootstrap Router (BSR) and one RP needs to
be configured in a PIM domain.
Enabling PIM
Follow these steps to configure general PIM parameters:
1. Use the router pim command in Global Configuration mode to enter Router
Configuration mode, as shown below:
MOT(config)#router pim
2. Use the network command in Router Configuration mode to define the network
IP address and subnet mask for the PIM network:
MOT(config-pim)#network <ip-address> <wild-card>
where:
ip-address is the IP address of the PIM network.
wild-card is the wild-card mask for the PIM network.