3Com 10014298 Multicast Source Registration, Preparing to Configure, Configure Candidate RPs

Configuring PIM-SM 137

Figure 34 RPT Schematic Diagram

Multicast source S

RPT

join

Multicast source registration

Multicast Source Registration

RP

Receiver

Preparing to Configure

PIM-SM

When multicast source S sends a multicast packet to group G, the PIM-SM multicast router is responsible for encapsulating the packet into a registration packet upon receipt. It then sends the packet to the corresponding RP in unicast. If there are multiple PIM-SM multicast routers on a network segment, the Designated Router (DR) will be responsible for sending the multicast packet.

Tasks for preparing to Configure PIM-SM are described in the following sections:

■Configure Candidate RPs

■Configure BSRs

■Configure Static RP

Configure Candidate RPs

In a PIM-SM network, multiple RPs (candidate-RPs) can be configured. Each Candidate-RP (C-RP) is responsible for forwarding multicast packets with the destination addresses in a certain range. Configuring multiple C-RPs is to implement load balancing of the RP. These C-RPs are equal. All multicast routers calculate the RPs corresponding to multicast groups according to the same algorithm, after receiving the C-RP messages that the BSR advertises.

One RP can serve multiple multicast groups or all multicast groups. Each multicast group can only be uniquely correspondent to one RP at a time rather than multiple RPs.

Configure BSRs

The BSR is the management core in a PIM-SM network. Candidate-RPs send announcement to the BSR, which is responsible for collecting and advertising the information about all candidate-RPs.

It should be noted that there can be only one BSR in a network but you can configure multiple candidate-BSRs. In this case, once a BSR fails, you can switch over to another BSR. A BSR is elected among the C-BSRs automatically. The C-BSR with the highest priority is elected as the BSR. If the priority is the same, the C-BSR with the largest IP address is elected as the BSR.

Configure Static RP

The router that serves as the RP is the core router of multicast routes. If the dynamic RP elected by BSR mechanism is invalid for some reason, the static RP can