Configuration Guide User guide

FastIron Configuration Guide 1537
53-1002494-02
PIM Sparse
The usage of the <group-addr> <mask-bits> parameter is the same as for the rp-candidate add
command.
If you enter both commands shown in the example above, the net effect is that the Layer 3 switch
becomes a candidate RP for groups 224.126.0.0 – 224.126.21.255 and groups 224.126.23.0 –
224.126.255.255.
Updating PIM-Sparse forwarding entries with new RP configuration
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
rp-address command.
To update the entries in a PIM sparse static multicast forwarding table with new RP configuration,
enter the following command at the privileged EXEC level of the CLI.
Brocade#clear pim rp-map
Syntax: clear pim rp-map
Statically specifying the RP
Brocade recommends that you use the PIM Sparse protocol 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 its IP address, you can do using the following CLI method.
Even if you explicitly specify the RP, by default the Layer 3 switch uses the set of candidate RPs
supplied by the BSR and overrides the specified RP for all group-to-RP mappings.
NOTE
Specify the same IP address as the RP on all PIM Sparse routers within the PIM Sparse domain.
Make sure the router is on the backbone or is otherwise well connected to the rest of the network.
To specify the IP address of the RP, enter commands such as the following.
Brocade(config)#router pim
Brocade(config-pim-router)#rp-address 207.95.7.1
Syntax: [no] rp-address <ip-addr>
The <ip-addr> parameter specifies the IP address of the RP.
The command in the example above identifies the router interface at IP address 207.95.7.1 as the
RP for the PIM Sparse domain. The Layer 3 switch will use the specified RP and ignore group-to-RP
mappings received from the BSR.
Changing the Shortest Path Tree (SPT) threshold
In a typical PIM Sparse domain, there may be two or more paths from a DR (designated router) for
a multicast source to a PIM group receiver:
• Path through the RP – This is the path the Layer 3 switch uses the first time it receives traffic
for a PIM group. However, the path through the RP may not be the shortest path from the Layer
3 switch to the receiver.