Setting up multiple routes with failover

[Ernest Rosser]

I'm a bit perplexed atm with trying to set up multiple failover routes on a 2821 router.  Let me say that I have more experieince in a switched network as routing is seldom required where I work atm.  Here's my problem. I have a routing table set up as follows but only the primary routes work.  The failover routes will not kick in once the primary route is not there.

ip route 10.32.11.0 255.255.255.0 128.32.8.11

ip route 10.32.11.0 255.255.255.0 128.32.24.11 100    

ip route 10.32.12.0 255.255.255.0 128.32.8.12

ip route 10.32.12.0 255.255.255.0 128.32.24.12 100

ip route 10.32.14.0 255.255.255.0 128.32.8.14

ip route 10.32.14.0 255.255.255.0 128.32.24.14 100

Ip addresses are not exact but it gets the point across.

Any help on why the failover routes are not failing over would be appreciated?  The failover routes work if I remove the primary route from the config.

[cadet alain · Accepted solution]

Hi,

You should use enhanced object tracking with IP SLA to track your routes.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/813-cisco-router-ipsla-basic.html

Regards

Alain

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[Bilal Nawaz]

Since you have static routes they will always remain in the routing table. The prefered primary routes will always have a better metric than your secondary routes. So the router will always prefer those ones.

You could set up IP SLA and tracking for your static routes to get around this.

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

[Ernest Rosser]

So something like this:

ip sla1

icmp-echo 128.32.8.11

frequency 5

timeout 1000

ip sla schedule 1 life forever start-time now

track 1 ip sla 1 reachability

ip sla2

icmp-echo 128.32.8.12

frequency 5

timeout 1000

ip sla schedule 2 life forever start-time now

track 2 ip sla 2 reachabiltiy

ip route 10.32.11.0 255.255.255.0 128.32.8.11 track 1

ip route 10.32.11.0 255.255.255.0 128.32.24.11 20

ip route 10.32.12.0 255.255.255.0 128.32.8.12 track 2

ip route 10.32.12.0 255.255.255.0 128.32.24.12 20

That should work if i understand the SLA feature correctly?

[Bilal Nawaz]

Hello Ernest,
This seems to be correct to my understanding. SLA commands vary from IOS versions.
Track keyword should be on your primary route

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[Ernest Rosser]

I forgot to mention is set up as a router on a stick.  Should this cause problems?  I'm limited to time on this router because it's used in a lab environment.  i have it scheduled for downtime tomorrow morning so i want to go in as prepared as possible.  Thanks for the help so far.

[Bilal Nawaz]

This should not be a problem and would still work. I will test this too.

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[Bilal Nawaz]

Hi Ernest,

My IOS and config was different from your example and from the link that Cadet provided. I had the following scenario:

From R1, static route to 100.0.0.1 tracking the reachability of 1.1.1.2:

R1 Config:

ip sla monitor 1

type echo protocol ipIcmpEcho 1.1.1.2

frequency 5

ip sla monitor schedule 1 life forever start-time now

!

track 1 rtr 1 reachability

!        

interface FastEthernet0/0

ip address 1.1.1.1 255.255.255.0

duplex auto

speed auto

!

ip route 100.0.0.1 255.255.255.255 1.1.1.2 track 1

All I did was shut the fa0/0 interface on R2 down to make 1.1.1.2 unreachable and then I had lost the route to 100.0.0.1.

When brought R2's interface back up so 1.1.1.2 was reachable, it reinstalled the static route back.

In your case, the floating static routes with the metric of 20, would then take over since they will remain in the routing table. When reachability returns, the primary is then installed back in to the routing table.

Hope this helps.

[Ernest Rosser]

Yes,

Thank you all for your help.  I assumed SLA was the option but wasn't sure.  Now I just need to purchase the Enterprise license.

[Bilal Nawaz]

Please rate useful posts and remember to mark any solved questions as answered. Thank you.