Cisco IOS Cookbook, 2nd Edition

Route Tagging

Problem

You want RIP to include a tag when it distributes specific routes to prevent routing loops when redistributing between routing protocols.

Solution

RIP Version 2 allows you to tag external routes. For a static route, for example, the configuration looks like this:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip route 0.0.0.0 0.0.0.0 172.25.1.1
Router1(config)#access-list 7 permit 0.0.0.0
Router1(config)#route-map TAGGING permit 10
Router1(config-route-map)# match ip address 7
Router1(config-route-map)# set tag 5
Router1(config-route-map)#exit
Router1(config)#router rip
Router1(config-router)#redistribute static route-map TAGGING
Router1(config-router)#exit
Router1(config)#end
Router1#

Discussion

You can only apply a route tag to external routes; that is, routes that are not learned from RIP. The example shows a static route, but you can apply a tag to routes learned from other routing protocols in exactly the same way. For example, the following code shows how to apply a tag to certain routes learned via EIGRP:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#access-list 7 permit 192.168.1.0
Router1(config)#route-map TAGGING permit 10
Router1(config-route-map)#match ip address 7
Router1(config-route-map)#set tag 5
Router1(config-route-map)#exit
Router1(config)#router eigrp 65530
Router1(config-router)#network 192.168.1.0
Router1(config-router)#exit Router1(config)# ...