Default route failover not working properly

[Ricky S]

Hey folks, I am having an issue with the WAN failover between a high speed internet connection and 3g Cellular backup

I have below route statements in the configuration

ip route 0.0.0.0 0.0.0.0 1xx.1xx.1xx.1 10
ip route 0.0.0.0 0.0.0.0 cellular0/0/0 20

Default route points to local high speed gateway as preferred route.

If there was a link failure on the primary interface of the router it will automatically switch to next best path which is cellular in this case. Once the link gets restored, router automatically flips back to the better route.
Problem happens if the local link DOES NOT fail but the Internet provider has some issues downstream. When this happens, default route still points out 1xx.1xx.1xx.1 as it doesn't detect the failure and default route never goes to cellular0/0/0

I decided to create an SLA object 55 where I would ping an IP on the internet sourced from my outside interface. I then created a Track 3 object which monitors the state of SLA 55. If track 3 is up, default route points out 1xx.1xx.1xx.1 and if track 3 goes down, default route would point out cellular 0/0/0.

ip route 0.0.0.0 0.0.0.0 1xx.1xx.1xx.1 190 track 3
ip route 0.0.0.0 0.0.0.0 cellular0/0/0 210

This works partially, in that it fails over to cellular but never flips back since SLA 55 can't ping the IP address on the internet from the outside interface until the default route gets pointed to the high speed gateway, which won't happen since track 3 is down.

So there is my issue.

Is there anything you folks can suggest I could try?

[Kelvin Willacey · Accepted solution]

You could try adding a static route that points out your primary Internet connection for the IP address that the SLA is pinging.

[Richard Burts · Accepted solution]

I have a customer with a situation very similar to what is described in this thread. I used the solution of a host specific static route pointed out the primary high speed interface. It worked quite well.

HTH

Rick

[Ricky S]

Thanks folks. I tried that before but for some reason it didn't work for me i.e. adding a static route out physical interface for the IP SLA is pinging.

However I modified it a bit by instead pointing it to the gateway IP of my ISP and it worked.

ip route x.x.x.x 255.255.255.255

Now I am able to succesfully failover and revert back my default route.

Thanks again!

ip sla 55

icmp-echo x.x.x.x source-interface GigabitEthernet0/0

frequency 30

ip sla schedule 55 life forever start-time now

!

!
track 3 ip sla 55
delay down 31 up 60

!

ip route 0.0.0.0 0.0.0.0 192.168.7.1 190 track 3

ip route 0.0.0.0 0.0.0.0 Cellular0/0/0 195

ip route x.x.x.x 255.255.255.255 192.168.7.1