IP SLA Tracking to change default route

cisco.balch · ‎01-26-2009

I have a series of routers that have local access to the Internet as well as a connection into an MPLS network.

The default route for Internet traffic is the local connection - I have an IP SLA Monitor hor HTTP set up to change the default route to the MPLS network if the sla monitor fails.

Two questions...

When failover occurs presumably the sla monitor will continue to operate but now via the default route over the MPLS network - How to cause the default route to fail back to the loacl connection when the local internet connection comes back up.

And 2... I would really like to get notified that the failiover has happened - how do I generate a syslog entry when the IP SLA monitor fails or when the default rout is modified.

My IOS config is...

ip sla monitor 600

type http operation get url http://www.cisco.com source-ipaddr 10.30.1.12

frequency 60

timeout 10000

ip sla monitor schedule 600 life forever start-time now

track 1 rtr 600 reachability

ip route 0.0.0.0 0.0.0.0 10.202.209.3 track 1 (the local Internet connection)

ip route 0.0.0.0 0.0.0.0 172.26.28.45 10 (The MPLS Connection)

Edison Ortiz · ‎01-26-2009

Ideally, you want to monitor an IP that is directly connected to the intended interface.

If you are monitoring an IP and that IP is also available via the secondary gateway, the SLA will never failover back to the primary gateway as the path is valid.

For monitoring, you will use SNMP traps:

http://www.cisco.com/en/US/docs/ios/12_4/ip_sla/configuration/guide/hsthresh.html

HTH,

__

Edison.