Adding secondary ip route

Unanswered Question
Dec 18th, 2007


We are having two ethernet links ( provided by service provider for WAN connectivity ). We need to configure failover routing that is if first link fails traffic should be routed via second link. As we are having connectivity via ethernet , locally router can not sence that link is down and then route traffic to second link. Only way to check that if first link is working or not working is to check IP address connectivity at second end. That means if my router is not able to contact other end of the first link , it should route that subnet to second link.This is similar to dialer-watch concept, when a particular subnet is not available in routing table it will triger ISDN.

Here is example

location A :

subnet : Network_A

ethernet(WAN_FIRST_LINK) : A.B.C.D1

ethernet (WANLINK_SECOND_LINK ) : P.Q.R.S1

location B :

subnet :Network_B

ethernet (WAN_FIRST_LINK) : A.B.C.D2

ethernet (WAN_SECOND_LINK) P.Q.R.S2

Now if location A router can not contact A.B.C.D1 then it shoud route the traffic on P.Q.R.S1

Any link on

This is similar to if -then -else statement in higher end programming lanuage.

Thanks in advance


I have this problem too.
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anilgangwani88 Tue, 12/18/2007 - 22:34

you an track ethernet interface using sla

Ip sla 11

Icmp-echo < to the Primary interface to which tracking is done> source-interface Gi0/0

frequency 5

ip sla schedule 11 start-time now life forever

Track 22 rtr 11 reachability

use static routes for both links with adjustable admin distance for primary and secondary paths .


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