ISDN Backup with floating static route issue..

Answered Question
Jun 26th, 2008


This issue is with ISDN Backup with floating static route.

Network Setup is as follows -

1. Branch router connects to Data Center and DR with individual E1 leased lines.

2. Branch router is provided with one ISDN BRI link as backup.

3. As per customer requirement, Dialer Interface 1 should dial and establish a backup connection to the DC in case of Both the Leased Lines of DC & DR has failed.

4. And Dialer Interface 2 should dial and establish a backup connection to the DR incases of complete DC failure and Leased Line from Branch to DR also has failed.

5. To achieve the backup connectivity with respect to the above points No# 3 & 4. I have configured two floating static routes to provide the backup connectivity from every Branch router (no backup interface configuration). One floating static route pointing to the dialer interface of Data Center and another floating static route with highest AD value than all the routes pointing towards to the dialer interface of the DR.

6. Interesting traffic has been configured to trigger the ISDN calls from the Branch to the DC & DR.

7. When both the leased lines have failed, it is observed Dialer 1 establishing the backup connection to the Data Center.

Problem facing -

1. When any one of two leased lines of the Branch returns back to operation. It is noticed that Dialer 1 will still continue to make calls until manually some one shuts down the Dialer Interface at the DC. The call never ends until manually the dialer interface has been shutdown, even after the dialer idle-timeout has expired ie., 180 secs.

After any one leased line has returned back to operation. And when I tracert to the DC server - the branch takes the Leased Line path instead of the ISDN Dialer interface. Hence there is no interesting traffic to keep the Dialer Interface with floating static route ACTIVE. But still the ISDN dialer continues to make calls to the DC until some one manually shuts down the Dialer Interface at the DC.

Please can any one help me to solve this issue. Is there any configuration with respect to the above configuration explained - to automatically bring down the ISDN Dialer interface when there is no interesting traffic.


Keshava Raju

I have this problem too.
0 votes
Correct Answer by Pravin Phadte about 8 years 7 months ago


It would have been good if there were configs attached. That would had helped in suggesting any troubleshooing steps.

I feel the problem to be is with the idel timeouts.

Below is the link go through it and you will find and answer.



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Overall Rating: 5 (1 ratings)
keshavahp Fri, 06/27/2008 - 19:43

Hello Mr. Pravin,

Many thanks! it worked. Thanks for the document.


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