Policy-Based Routing

The Policy-Based Routing feature is a process whereby a device puts packets through a route map before routing the packets. The route map determines which packets are routed next to which device. Policy-based routing is a more flexible mechanism for routing packets than destination routing.

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Information About Policy-Based Routing

Policy-Based Routing

Policy-based routing is a process whereby the device puts packets through a route map before routing them. The route map determines which packets are routed next to which device. You might enable policy-based routing if you want certain packets to be routed in a certain way other than the obvious shortest path. Possible applications for policy-based routing are to provide equal access, protocol-sensitive routing, source-sensitive routing, routing based on interactive versus batch traffic, and routing based on dedicated links. Policy-based routing is a more flexible mechanism for routing packets than destination routing.

To enable policy-based routing, you must identify which route map to use for policy-based routing and create the route map. The route map itself specifies the match criteria and the resulting action if all of the match clauses are met.

To enable policy-based routing on an interface, indicate which route map the device should use by using the ip policy route-map map-tag command in interface configuration mode. A packet arriving on the specified interface is subject to policy-based routing except when its destination IP address is the same as the IP address of the device’s interface. This ip policy route-map command disables fast switching of all packets arriving on this interface.

To define the route map to be used for policy-based routing, use the route-map map-tag [permit] [sequence-number] global configuration command.

To display the cache entries in the policy route cache, use the show ip cache policy command.


Note

PBR is supported only in a video template.

Restrictions for Policy-Based Routing

  • The following command is not supported: 
    ip local policy route-map <route-map_name>

    Note
    Local Policy based routing is not supported.

How to Configure Policy-Based Routing

Configuring Policy-Based Routing

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. sdm prefer video
  4. ip access-list extended <name>
  5. permit protocol source [source-wildcard] destination [destination-wildcard]
  6. exit
  7. Route-map <route_map_name> permit <sequence_number>
  8. match ip address <match_criteria_name>
  9. set ip next-hop <ip_address> set ip vrf <vrf_name> next-hop <ip_address> set vrf <vrf_name>
  10. exit
  11. interface type number
  12. ip policy route-map <route_map_name>
  13. exit

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

sdm prefer video

Example:

Router(config)#sdm prefer video
Configures the video mode.
Note 

This requires a reload of the system. The configuration of the following steps will only be effective after the SDM template is changed to video template.

Step 4

ip access-list extended <name>

Example:


Router(config)#ip access-list extended pbr-acl1

Configures an Extended ACL named "pbr-acl1" and enters extended-acl configuration mode.

Step 5

permit protocol source [source-wildcard] destination [destination-wildcard]

Example:


Router(config-ext-nacl)#permit ip 10.0.0.0 0.255.255.255 200.0.0.0 0.255.255.255

Creates a match statement to match the specified source & destination IP address.

Step 6

exit

Example:


Router(config-ext-nacl)#exit

Returns to global configuration mode.

Step 7

Route-map <route_map_name> permit <sequence_number>

Example:


Router(config)#route-map pbr permit 10

Creates a Route-map statement named "pbr" for redistributing routes from one routing protocol into another routing protocol or enables policy-based routing and enters route-map configuration mode.

Step 8

match ip address <match_criteria_name>

Example:


Router(config-route-map)#match ip address pbr-acl1

Defines the match criteria by which packets are examined to learn if they will be policy-based routed.

Step 9

set ip next-hop <ip_address> set ip vrf <vrf_name> next-hop <ip_address> set vrf <vrf_name>

Example:


Router(config-route-map)#set ip next-hop 30.0.0.2
Router(config-route-map)#set ip vrf vrf1 next-hop 30.0.0.1
Router(config-route-map)#set vrf vrf1

Specifies where to output packets that pass a match clause of a route map for policy routing.

Step 10

exit

Example:


Router(config-route-map)#exit

Returns to global configuration mode.

Step 11

interface type number

Example:


Router(config)#interface Gi0/0/10

Configures an interface type and enters interface configuration mode.

Step 12

ip policy route-map <route_map_name>

Example:


Router(config-if)#ip policy route-map pbr

Identifies a route map to use for policy routing on an interface.

Step 13

exit

Example:


Router(config-if)#exit

Returns to global configuration mode.

Verifying Policy-Based Routing

Use this command to verify that the SDM template is changed to video template.

show sdm prefer current 

PE1#show sdm prefer current 
The current template is "video" template

Use this command to display the cache entries in the policy route cache.

show ip cache policy 

CE1#show ip policy
Interface      Route map
Gi0/0/10       equal-access
CE1#

Configuration Examples for Policy-Based Routing

This section shows sample configuration for Policy-Based Routing.

Example: Policy-Based Routing

The following is a sample configuration for Policy-Based Routing. 
Device# conf t
Device(config)# access-list 1 permit host 10.1.1.1
Device(config)# access-list 2 permit host 172.17.2.2
Device(config)# exit

Device# conf t
Device(config)# route-map equal-access permit 10
Device(config-route-map)# match ip address 1
Device(config-route-map)# set ip next-hop 172.16.6.6
Device(config-route-map)# exit
Device(config)# route-map equal-access permit 20
Device(config-route-map)# match ip address 2
Device(config-route-map)# set ip next-hop 192.168.7.7
Device(config-route-map)# exit
Device(config)#exit

Device# conf t
Device(config)# interface GigabitEthernet0/0/2
Device(config-if)# ip policy route-map equal-access
Device(config-if)# exit

Additional References

Related Documents

Related Topic

Document Title

IP routing protocol-independent commands

Cisco IOS IP Routing: Protocol-Independent Command Reference

Technical Assistance

Description

Link

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http://www.cisco.com/cisco/web/support/index.html

Feature Information for Policy-Based Routing

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for Policy-Based Routing