Multiple default route and tracking ip sla

[lafourchette]

Hello,

We just put a ISR1921 in one of our sites and we ran into a problem. We have this router that make a "load-balancing" between 3 modem/router from our ISP on 3 different ADSL lines. Except that with 2 lines he can, with 3 he cannot. This TOTALLY WORKS with only 2 default route.

Each route is tracking that the ISP router is up so people only have to unpower it when it's down. It should load-balance across all the 3 route, but we can't join anything if the 3 routes are up. I have to remove one of the default route. The tracking run smoothly. If we unplug one of the router, it totally works.

See below for configuration.

track 1 ip sla 1 reachability

!

track 2 ip sla 2 reachability

!

track 3 ip sla 3 reachability

ip route 0.0.0.0 0.0.0.0 192.168.0.2 track 1

ip route 0.0.0.0 0.0.0.0 192.168.0.3 track 2

ip route 0.0.0.0 0.0.0.0 192.168.0.4 track 3

ip sla 1

icmp-echo 192.168.0.2

threshold 700

timeout 1000

frequency 3

ip sla schedule 1 life forever start-time now

ip sla 2 

icmp-echo 192.168.0.3

threshold 700

timeout 1000

frequency 3

ip sla schedule 2 life forever start-time now

ip sla 3

icmp-echo 192.168.0.4

threshold 700

timeout 1000

frequency 3

ip sla schedule 3 life forever start-time now

Any idea is REALLY APPRECIATED.

[cadet alain]

Hi,

You say it can't load balance with 3 lines, what do you mean by that?  Can you post your routing table output as well as sh ip int br.

Regards.

Alain.

[chia hao chang]

I think your multiple default route won't work

if one of your WAN link broken

how could you remove that link?

ip sla just detect one IP to know your link is still alive

in your configuration, I cannot find action when any ip sla detect fair

[Richard Burts]

Jonathan

You have given us some information but not enough for us to really understand the issue or to give you a really helpful answer. If you can provide additional details we might be able to provide better answers.

I do not see any reason why ip track would not function in the case of three static default routes and believe the problem is not really a failure of ip track. From your description of it being ADSL I am guessing that there is a dialer involved. So I am guessing that there may be some issue in the way that you are getting the three ADSL interfaces into the dialer. Can you provide details about the configuration of the interfaces and of the dialer?

Also it would be helpful to understand the symptoms of the problem a bit better. You say that it does not work with three active interfaces. But what is not working? Is it not forwarding at all? Is it only forwarding through some interfaces and not through others? Is it forwarding but not balancing the way that you expect? In what way is it not working?

HTH

Rick