About Pim; Enabling Pim - Motorola BSR 2000 Configuration And Management Manual

Release 1.0

About PIM

Protocol-Independent Multicast (PIM) is used to efficiently route to multicast groups
that might span wide-area and inter-domain internetworks. It is referred to as
"protocol independent" because it is not dependent on any particular unicast routing
protocol.
PIM is IP routing protocol independent because it can use any unicast routing
information to forward multicast traffic. Even though PIM is a multicast routing
protocol, it uses the unicast routing table to perform Reverse Path Forwarding (RPF),
instead of creating an independent multicast routing table. However, unlike most
unicast routing protocols, PIM does not send and receive multicast routing updates
between routers.
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 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
2. Use the network command in Router Configuration mode to define the network
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Retrieving PIM Unicast Routes
Configuration mode:
MOT(config)# router pim
IP address and subnet mask for the PIM network:
MOT(config-pim)# network <A.B.C.D> <A.B.C.D>
where:
A.B.C.D is the IP address of the PIM network.
Configuring IP Multicast Routing
MGBI 9-3