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New Member

ISDN backup issue on a 2650 router

Hi,

I have a problem with 2 x 2650 routers implementing ISDN backup. The ISDN line will only come up if both serial links from both ends are disconnected !! If one end's serial link is disconnected, the other routers serial connection seems to bounce periodically, but never detect that the serial link has been disconnected at the other end i.e.

*Apr 4 19:20:56: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up

*Apr 4 19:21:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down

*Apr 4 19:21:26: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up

*Apr 4 19:21:54: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down

*Apr 4 19:21:56: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up

*Apr 4 19:22:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down

The timings look consistent, which leads me to suggest it is something to do with the provider. Is there any way to inform the router that the remote serial link is down, and therefore action ISDN backup. I did try dialer watches, however this did not work either.

The only way to get the ISDN to work is to disconnect both links.

Any help appreciated.

1 REPLY
New Member

Re: ISDN backup issue on a 2650 router

Check your backup delay settings, as the default is to bring the interface up as soon as the link goes down.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/dial_r/drprt4/drdbaks.htm

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