Updating PIM-Sparse Forwarding Entries with New RP Static Configuration

You can define a static RP instead of using the PIM Sparse RP election process. After defining a static RP, you must clear out the old RP configuration.

It is recommended that you use the PIM Sparse protocol’s RP election process so that a backup RP can automatically take over if the active RP router becomes unavailable. However, if you do not want the RP to be selected by the RP election process but instead you want to explicitly identify the RP by IP address, use the rp-address command.

If you explicitly specify the RP, the device uses the specified RP for all group-to-RP mappings and overrides the set of candidate RPs supplied by the BSR.

Note: Specify the same IP address as the RP on all PIM Sparse devices within the PIM Sparse domain. Make sure the device is on the backbone or is otherwise well connected to the rest of the network.

If you make changes to your static RP configuration, the entries in the PIM-Sparse multicast forwarding table continue to use the old RP configuration until they are aged out.

The clear pim rp-map command allows you to update the entries in the static multicast forwarding table immediately after making RP configuration changes. This command is meant to be used with the rp-address command.

  1. Enter global configuration mode. 
    device# configure terminal
  2. Globally enable PIM. 
    device(config)# router pim
  3. Create a static RP IP address. 
    device(config-pim-router)# rp-address 207.95.7.1
    The command in this example identifies the device interface at IP address 207.95.7.1 as the RP for the PIM Sparse domain. The device uses the specified RP and ignore group-to-RP mappings received from the BSR.
  4. Exit to privileged EXEC configuration mode. 
    device(config-pim-router)# end
  5. To update the entries in a PIM sparse static multicast forwarding table with new RP configuration, you must clear out the old RP entries. 
    device# clear ip pim rp-map

The following example configures a static RP for the PIM Sparse domain and clears out existing RP entries. 

device# configure terminal
device(config)# router pim
device(config-pim-router)# rp-address 207.95.7.1
device(config-pim-router)# end
device# clear ip pim rp-map
Parent topic: Configuring PIM Sparse