The PBR Recursive Next Hop feature enhances route maps to enable configuration of a recursive next-hop IP address that is used by policy-based routing (PBR). The recursive next-hop IP address is installed in the routing table and can be a subnet that is not directly connected. If the recursive next-hop IP address is not available, packets are routed using a default route.
Because Cisco Express Forwarding (CEF) or process switching provides the infrastructure, the benefit of this feature is the CEF loadsharing.
Feature History for the PBR Recursive Next Hop Feature
This feature was introduced.
This feature was integrated into Cisco IOS Release 12.3(14)T.
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The infrastructure provided by CEF or process switching performs the recursion to the next-hop IP address. The configuration sequence, which affects routing, is as follows:
If both a next-hop and a recursive next-hop IP address are present in the same route-map entry, the next-hop is used. If the next-hop is not available, the recursive next-hop is used. If the recursive next-hop is not available and no other IP address is present, the packet is routed using the default routing table; it is not dropped. If the packet is supposed to be dropped, use the setipnext-hopcommand with the recursive keyword followed by a setinterfacenull0 configuration.
Match interface is not supported on Cisco Catalyst 3750 series devices.
Perform this task to set the IP address for the recursive next-hop router.
Before You Begin
If loadsharing is required, CEF loadsharing should be configured for per-packet or per-destination loadsharing. Loadbalancing should be done over all equal-cost routes to the subnet that have been configured by the setipnext-hoprecursivecommand.
This functionality should be available in centralized and distributed systems.
Only one recursive next-hop IP address is supported per route-map entry.
Router(config-route-map)# set ip next-hop recursive 10.20.3.3
Sets a recursive next-hop IP address.
This configuration does not ensure that packets get routed using the recursive IP address if an intermediate IP address is a shorter route to the destination.
Router(config-route-map)# match ip address 101
Sets an access list to be matched.
Exits route-map configuration mode and returns to privileged EXEC mode.
Verifying the Recursive Next-Hop Configuration
To verify the recursive next-hop configuration, perform the following steps.
1.showrunning-config | beginabccomp
showrunning-config | beginabccomp
Use this command to verify the IP addresses for a next-hop and recursive next-hop IP address, for example:
Router# show running-config
| begin abccomp
route-map abccomp permit 10
match ip address 101 ! Defines the match criteria for an access list.
set ip next-hop recursive 10.3.3.3 ! If the match criteria are met, the recursive IP address is set.
set ip next-hop 10.1.1.1 10.2.2.2 10.4.4.4
Use this command to display the route maps, for example:
Router# show route-map abccomp
route-map abccomp, permit, sequence 10
ip address (access-lists): 101
ip next-hop recursive 10.3.3.3
ip next-hop 10.1.1.1 10.2.2.2 10.4.4.4
Policy routing matches: 0 packets, 0 bytes
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