Reporting a state of an IP route

 

Have you ever wanted to be notified when your router loses a specific route (for example, the default route toward the Internet)? In IOS release 12.4T you can do it with a combination of Enhanced Object Tracking and Embedded Event Manager 2.2.As the first step, you configure a track object that will monitor the state of an IP route with the track ip route command.

track 100 ip route 0.0.0.0 0.0.0.0 reachability

After the track object has been created, you can monitor its state with an EEM applet (in the configuration example it only generates a syslog message, but you could also send an email to the network administrator).

event manager applet TrackRoute_0.0.0.0
 event track 100 state any
 action 1.0 syslog msg "route is $_track_state"

And now a test run ...

a1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
a1(config)#ip route 0.0.0.0 0.0.0.0 loopback 0
a1(config)#^Z
01:08:47: %SYS-5-CONFIG_I: Configured from console by console
01:08:51: %HA_EM-6-LOG: TrackRoute_0.0.0.0: route is up
a1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
a1(config)#interface loopback 0
a1(config-if)#shutdown
01:09:10: %SYS-5-CONFIG_I: Configured from console by console
01:09:11: %LINK-5-CHANGED: Interface Loopback0, changed state to administratively down
01:09:21: %HA_EM-6-LOG: TrackRoute_0.0.0.0: route is down

As you can see from the example, there is a significant delay before the track object responds to a route change. You can adjust this delay with the track timer ip route seconds global configuration command (default is 15 seconds).