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New Member

ISDN dial idle timeout problem

Dear All,

I have a scenario where central location is connected to remote location through lease line with ISDN backup. Router need to be configured to auto switch between lease line to ISDN when lease line fails, but ISDN should only initiate the call when data packets are flowing & should disconnect after idle timeout. Presently ISDN line auto switch when lease line fails, but ISDN call is not disconnecting as rip update are flowing over ISDN line, Due to this ISDN line is connected even if the data packets are not flowing.

Tried configuring BRI port on Static route, but as ethernet is on RIP it sends the routing update keeping the ISDN line busy.

Solution Tried

1) Configured passive interface on BRI port of both local & remote router. Due to this action rip updates will not be send to BRI port of both the router.

After configuring passive interface we are able ping from local router to remote router, but we are not able to ping from local PC to remote router.

2) Configured Snapshot Routing on BRI port of both local & remote router. One router will act as snapshot client & other will act as snapshot server. We configured active period & quite period. Call is getting initiated during the active period & is getting disconnected after idle timeout. Routing table is present even after call is disconnected, but the call is not getting initiated during the quiet period.

I want the single central ISDN line to server as a backup for all the remote locations in case of a lease line failure.

Also i want the ISDN line to dial from the remote end only (Static Route) when there is a lease line failure and there is a flow of data.

Workaround Config is Welcomed.

New Member

Re: ISDN dial idle timeout problem

You can try out the following options

1. Configure the interesting traffic using dialer list. (basically the data traffic based on ip address)

2. Apply the dialer list to the bri0 via dialer group statement.

2.At the remote location configure a backup interface bri0 command on the serial interface.

3. Configure backup delay command on the serial interface for idle timeout once the leased line is up.

Hope this might help you




Re: ISDN dial idle timeout problem

Turn off rip on the dial line (passive interface at both ends) and use floating static routes. You can also get rid of the backup interface commands. When the core router looses its learned route over the serial line traffic will flow to the dial line. Make sure the static routes point to the other end of the dial line and use multiple dailer maps with unique serial addresses so multiple sites can be backed up.


Re: ISDN dial idle timeout problem

access-list 100 deny rip any any

access-list 100 permit ip any any


dialer-list 1 protocol ip list 100

RIP is no longer "interesting" and will not keep the ISDN link up.

Good luck and have fun!

Vincent C Jones