DDR ISDN back up line coming up to often

Unanswered Question
Apr 24th, 2009

I have a remote site in Toronto Canada, This site is connected with an IPSEC VPN across the Internet with an added GRE tunnel to carry EIGRP traffic. I have an ISDN line that should only come up when one of the watched routes at Headquarters goes down. It is coming up all the time. I have included the router config and a copy of the log file with "debug dialer" and debug ISDN events" turned on. Is there anything obvious I am doing wrong? Is this just my ISP bouncing or flapping? Perhaps I need to add some type of EIGRP hold timer so the DDR won't kick in so quickly. I would appreciate any suggestions or opinions.

I have this problem too.
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Giuseppe Larosa Fri, 04/24/2009 - 10:40

Hello Steve,

what is the output of

sh ip route

do you see an EIGRP route via the GRE tunnel interface ?

is the route present and stable ?

EIGRP routes don't age so the uptime of the route if present tells you if the route is present.

Notice that dialer watch looks for an exact match including the subnet mask, an aggregate route including is not considered.



if the route is present and stable with the specified prefix length I have some doubts if dialer watch works well only with physical primary interface like a lan interface or a primary interface.

But I wouldn't know why.

Another final note:

if the router is only one you can try to use other features:

if you can use GRE keepalives you can track the state of the GRE tunnel and you can use the BRI as the backup interface with backup command.

Hope to help


srroeder Fri, 04/24/2009 - 10:47


Thank you for the reply.

Here is the output of the sho ip route command.

toprt01#sho ip route

Routing entry for

Known via "eigrp 1807", distance 90, metric 297247232, type internal

Redistributing via eigrp 1807

Last update from on Tunnel0, 01:01:03 ago

Routing Descriptor Blocks:

*, from, 00:01:03 ago, via Tunnel0

Route metric is 297247232, traffic share count is 1

Total delay is 500110 microseconds, minimum bandwidth is 9 Kbit

Reliability 255/255, minimum MTU 1476 bytes

Loading 56/255, Hops 2

Giuseppe Larosa Fri, 04/24/2009 - 10:55

Hello Steve,

the route is actually present and stable.

I'm afraid you are facing a limitation of dialer-watch with logical primary interfaces.

If you had two routers in the remote site the primary interface for the backup router would be the lan interface towards primary router.

I've used dialer watch successfully in a scenario like the one I've described just above.

Try to look if your routers at HQ and remote site support GRE keepalives (this is IOS dependent) in that case you could try to used the backup command

Hope to help



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