Enable Fast-Switched PBR

Enable Fast-Switched PBR

IP PBR can now be fast-switched. Prior to Cisco IOS Release 12.0, PBR could only be process-switched, which meant that on most platforms the switching rate was approximately 1000 to 10,000 packets per second. This speed was not fast enough for many applications. Users who need PBR to occur at faster speeds can now implement PBR without slowing down the router.

Fast-switched PBR supports all of the match commands and most of the set commands, with the following restrictions:

•The set ip default next-hop and set default interface commands are not supported.

•The set interface command is supported only over point-to-point links, unless a route-cache entry exists using the same interface specified in the set interface command in the route map. Also, at the process level, the routing table is consulted to determine if the interface is on a reasonable path to the destination. During fast switching, the software does not make this check. Instead, if the packet matches, the software blindly forwards the packet to the specified interface.

PBR must be configured before you configure fast-switched PBR. Fast switching of PBR is disabled by default. To enable fast-switched PBR, use the following command in interface configuration mode:

Command	Purpose
ip route-cache policy	Enable fast switching of PBR.

To display the cache entries in the policy route cache, use the show ip cache policy command. Use the show ip policy command to display which route map is associated with which interface. 

Ref:Configuring Policy-Based Routing