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Cisco IOS Cookbook, 2nd Edition by Ian Brown, Kevin Dooley

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Configuring Anycast RP

Problem

You want to configure two or more RPs and have your routers simply use whichever one is closest.

Solution

One of the most significant shortcomings of PIM-SM is that within any given multicast network boundaries, there can be only one RP for any multicast group. This has several potential problems including slow convergence after an active RP failure and potentially extra hops required to reach a distant RP. Anycast RP solves these problems.

The first RP configuration looks like this:

Router-RP1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router-RP1(config)#ip multicast-routing
Router-RP1(config)#interface Loopback0
Router-RP1(config-if)# ip address 10.4.4.4 255.255.255.255
Router-RP1(config-if)#exit
Router-RP1(config)#interface Loopback1
Router-RP1(config-if)# ip address 192.168.99.1 255.255.255.255
Router-RP1(config-if)# ip pim sparse-dense-mode
Router-RP1(config-if)#exit
Router-RP1(config)#ip pim send-rp-announce Loopback1 scope 16 group-list 22
Router-RP1(config)#ip pim send-rp-discovery Loopback1 scope 16
Router-RP1(config)#ip msdp peer 10.5.5.5 connect-source Loopback0
Router-RP1(config)#access-list 22 permit 239.0.0.0 0.255.255.255.255
Router-RP1(config)#end
Router-RP1#

The configuration for the second RP router is almost identical:

Router-RP2#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router-RP2(config)#ip multicast-routing
Router-RP2(config)#interface Loopback0 Router-RP2(config-if)# ...

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