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Webcast-Catalyst9k
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No isdn dial out with 801 after reload / restart

We are using 801 routers (uk isdn). If a router is turned on from

cold, or reloaded, we find that it will not initially dial.

We have found two ways of making the router dial just after such a

restart. The first is to physically disconnect the isdn line and then

plug it back in. Once this has been done the router will dial out

correctly, drop the line and so on. The router will continue to work

properly ever more until it is reloaded, when the same problem comes

up. The other method of getting the router to work is to issue a no

shutdown command for the bri0 interface. Doing this just the once

then makes the dial out interface work until the next restart.

The real problem with this is that dial out will not initially work

after a reload/restart. Such a situation can easily occur after a

power failure or if the router is reloaded remotely. Someone then

needs to physically unplug and reconnect the isdn line to get things

working normally. We have noticed this before but it is now causing

us some practical problems. Has anyone seen the same and is there an

answer?

2 REPLIES
Silver

Re: No isdn dial out with 801 after reload / restart

I had a similar problem (which may or may not be related) using an 804 (US ni-1 ISDN) where it would not answer an incoming voice call until after an outgoing call (voice or data) was placed. That one went away about a year ago with a new IOS release. If I recall correctly, the work around was to configure the router to immediately bring up the D channel rather than wait like it is supposed to using the " isdn twait-disable" command on the BRI0 interface.

I also found (with the 804) that ISDN problems seem to come and go depending upon which IOS release was loaded. You may find that moving to a newer release (or back to an older one if on the latest) magically cures your problem. Just don't get too confident, because you probably just traded in the problem which bothered you for one you don't know about yet :-(

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

Purple

Re: No isdn dial out with 801 after reload / restart

We have seen problems like this with isdn , isdn is still shakey at best sometimes . After a reload if you get BRI's that do not show "multiple frames established " you can usually fix it by doing a "clear int bri port # ", this forces the router to requery the isdn switch . Newer versions of code can also send layer 2 traps for isdn , you need to be in the 12.X train to use these though .

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