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New Member

ISDN Backup on 1841 (Configuration?)


I have an 1841 router which is configured to use both Fa0/0 and Fa0/1 for redundant connectivity to our ISP.

I have installed a WIC-1B-U-V2 card in one of the available slots. This card will be connected to a 'last-resort' ISDN service provider.

What configuration do I need to provide this failover capability? Since the ISDN connection is expensive, I would like to make sure it only connects when absolutely necessary. I appreciate any guidance.



Re: ISDN Backup on 1841 (Configuration?)

Hi Charlie

You need to enable Object Tracking feature on your router to track the ethernet interface to trigger the isdn back up..

you can refer the below link for the same.


New Member

Re: ISDN Backup on 1841 (Configuration?)

Thanks for the reply,

Ive got object tracking currently configured to handle failover between the 2 ethernet interfaces. I am pleasantly surprised if I can use the same feature to provide the failover to ISDN connectivity should both Ethernet interfaces go down.

But, I am looking for some beginner guidance in setting up the ISDN interface to dial and connect, then Ill have to deal with how this can be controlled via object tracking.


New Member

Re: ISDN Backup on 1841 (Configuration?)

Any suggestions on this? I need to get this interface going, but I have not done a dial-out over ISDN with cisco.

Any pointers?

New Member

Re: ISDN Backup on 1841 (Configuration?)


Use reliable static routes ( object tracking) to track the two ethernet and a static route with higher AD to the BRI interface so that if the object tracking finds both the ethernet down it will fall back to the next available route which is towards the ISDN.

Thanks and Regards,



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