MSDP-based Anycast RP

MSDP peer relationships are set up between RPs to exchange SA messages, so that source information registered locally can be shared by the RPs. Anycast RP is the application of this feature in one PIM-SM domain.

In a traditional PIM-SM domain, all multicast groups map to one RP. When the network is overloaded or the traffic volume is high, many network problems occur, such as the heavy pressure of the RP, the slow convergence after the RP fails, and the non-optimal multicast forwarding path. By using Anycast RP, you can configure multiple RPs in a PIM-SM domain, assign the same IP address to these RPs, and set up MSDP peer relationships between these RPs. In this manner, the optimal RP path and load balancing can be implemented.

As shown in Figure 6-9, in the PIM-SM domain, the multicast sources, Source1 and Source2, send multicast data to the multicast group G. Receiver1 and Receiver2 are members of group G.

Figure 6-9 Networking diagram of Anycast RP

Do as follows to apply Anycast RP in a PIM-SM domain:

1. Select several routers in the PIM-SM domain, such as RouterA and RouterB in Figure 6-9.
2. Choose one loopback interface from each router, such as Loopback1 in Figure 6-9, and assign the same address to these interfaces.
3. Configure the RP. You can configure static RPs or C-RPs, as shown in Figure 6-9.
   • Static RP: Configure static RPs on all PIM-SM routers, and use the address of the interface Loopback1 on RouterA as the address of the RPs.
   • C-RP: Configure the two Loopback1 interfaces on RouterA and RouterB as C-RPs. Configure a C-BSR on the network. Ensure that the address of the C-RP must be different from the address of the C-BSR.
4. Set up an MSDP peer relationship between RouterA and RouterB. Do not use the interface addresses of the RPs.