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Cisco IOS Cookbook, 2nd Edition by Ian Brown, Kevin Dooley

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Using Policy-Based Routing to Route Based on Application Type

Problem

You want different applications to use different network links.

Solution

This example is similar to the previous one, except that instead of looking at the source address of the incoming IP packet, it looks at other protocol information such as TCP or UDP port number. The example redirects HTTP traffic (TCP port 80) for certain source addresses.

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#access-list 101 deny tcp 10.15.25.0 0.0.0.255 any eq www
Router(config)#access-list 101 permit tcp any any eq www
Router(config)#interface Ethernet0
Router(config-if)#ip address 10.15.22.7 255.255.255.0
Router(config-if)#ip policy route-map Websurfers
Router(config-if)#ip route-cache policy
Router(config-if)#exit
Router(config)#route-map Websurfers permit 10
Router(config-route-map)#match ip address 101
Router(config-route-map)#set ip next-hop 10.15.27.1
Router(config-route-map)#exit
Router(config)#route-map Websurfers permit 20
Router(config-route-map)#set ip default next-hop 10.15.26.1
Router(config-route-map)#end
Router#

This second example looks instead at the IP TOS field:

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#access-list 102 permit ip any any tos 4
Router(config)#interface Serial0
Router(config-if)#ip address 10.15.23.6 255.255.255.252
Router(config-if)#ip policy route-map High-priority Router(config-if)# ...

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