Automatic failover

Unanswered Question
May 31st, 2007


While trying to work out for auto failover, I came across this situation which I couldn?t figure out.

Two test dsl connection for a particular site. EIGRP is used between the core and the primary link and static routes with higher AD(215) is used for secondary link.

The idea is, to route the traffic via secondary link with a higher AD when the primary link goes down.

Initially things go fine. The system routs the traffic via the primary link. Once the PPP session goes down, EIGRP looses the neighbor relationship and the traffic is getting routed via the secondary link which is normal.

But, even after the primary link gets restored, the traffic is getting routed via the secondary link and its not switching back to the primary link which should doo.

Note : Attached the sample setup.



I have this problem too.
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spremkumar Thu, 05/31/2007 - 23:39

Hi Rajesh

As you have mentioned in your post sample setup is not available also can you post the config which you are trying out there ...


bjornarsb Thu, 05/31/2007 - 23:52


if we are supposed to help you with this you also have to post your configs :)

post a show sh ip route eigrp on test1 , when primary link is up again.



mark.j.hodge Fri, 06/01/2007 - 02:45

Check the routing table on the hosts. I suspect that when a failover occurs the hosts "learn" to route through the test2 router, when the lilnk recovers they don' unlearn this route.

This learning is done through ICMP redirects, if it is the cause, you can turn the feature off on an interface basis.

** Please rate posts if helpfull **

kradjesh13 Sun, 06/03/2007 - 22:11

The issue is fixed; apparently the faulty behavior is due to the routing problem. Initially I had the following set of commands in the core. I added because, the WAN address for the CPE is & 3. In the core also we have another loopback

redistribute connected

redistribute static

redistribute bgp XXXX metric 2000 255 255 1 1500

no redistribute eigrp

no redistribute eigrp


no auto-summary

autonomous-system XXXX


When I added network to EIGRP; the CPE formed relationship with and from there on it began to work fine.

Now, my point is how its forming relationship with and not with I cleared the EIGRP neighbors. But still is the neighbor for test 1.

test1#sh ip eigrp neighbors

IP-EIGRP neighbors for process XXXX

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

0 Di1 13 00:35:10 24 2604 0 13


test1#sh ip route eigrp XXXX is subnetted, 4 subnets

D EX [170/46251776] via, 00:36:52

D [90/48786176] via, 00:36:52

D [90/46354176] via, 00:36:52 is variably subnetted, 3 subnets, 2 masks

D EX [170/46251776] via, 00:36:52

D EX [170/46251776] via, 00:36:52

D EX [170/46226432] via, 00:36:52 is subnetted, 1 subnets

D EX [170/46354176] via, 00:36:52

D*EX [170/46228224] via, 00:36:52





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