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ISDN Call Disconnects - Error 100

Article Number: I013
Article Type: Info
Modified: January 13, 1999

SUMMARY

If you've ever encountered unusual ISDN disconnections on your Orbitor product, you may be wondering what some of the disconnect and error codes really mean. In most cases, these errors will not yield any secrets that are meant to be kept that way, but there are a few codes that will most often occur, and can cause the most grief to try and resolve.

This article will focus on one such error code -- 100. This error can occur for a variety of reasons, but most often they have nothing to do with the device making the call. To make matters worse, this error code can be symptomatic of a normal disconnect. To help guide you through understanding what this error code is telling you, you may find the following information useful.

MORE INFORMATION

What does this code mean?

Reviewing the ISDN specifications will not shed a lot of light on the cause or a solution. This error is often a "catch-all" error that literally means, "I didn't understand or don't like what you just said, so, I'm sending you this error code."

Keep in mind that when the Orbitor logs this error code, it isn't generating it, it is receiving it from some remote device in the ISDN connection chain. This is important to understand since this is usually caused by an error that has occurred on a switch, or that has been detected by a switch downstream of the Orbitor.

Did you dial the right number?

If the Orbitor has never made a successful ISDN call, do not rule out that you are dialing an incorrect number, or that one of the called numbers is invalid. Verify that you are truly dialing the proper ISDN number to reach the remote destination.

It connects and then disconnects

If the Orbitor logs what seems to be a proper connection, and then a disconnect with this error code, the error code is normally inconsequential and is symptomatic of the timing of the disconnection through the ISDN switched network. The next section explains this further.

It's often one of timing

If you do see this error following what seems to be a valid connection, you may wish to simply ignore it. However, what it is telling you is that some error was detected while the call was being disconnected. Some reasons for an ISDN switch to generate this error code might be that one end of the ISDN call has already been disconnected and terminated, while the other end is still propogating data. Data received at the other end where the call is already terminated is cause enough for the switch to generate the error.

Look to the destination for the cause

Following the previous thought, you may wish to ignore the error and try to find out if the destination is terminating the connection prematurely. When you start to diagnose this kind of problem, you will soon find that the real issue is a premature disconnection from the target of your call. There are many reasons for the target to reject the call, and many of these are beyond the scope of this article. However, it can often be attributed to either a Password authentication failure or some PPP LCP/NCP negotiations failure. In these cases, contacting the administrator of the destination router will be helpful. At minimum, review the configuration of the Orbitor's Remote Site profile for any obvious errors.

Last, but not least, line or interface errors

Various line or interface faults can cause failure of the call setup or teardown, but this is the least often cause of this error. If you've already ruled out the previous points, you should contact the Telephone company or PTT to report the error and to gain their assistance in diagnosing the faulty component. They will most probably perform various levels of diagnostics on the line and interfaces and will be able to isolate the cause down to the particular device failing.

Finally

As described above, this error code is often symptomatic of another fault, and isn't really an indication of the fault itself. By following some of the guidelines above, you should be able to isolate the cause of this problem, and determine a solution.

REFERENCES

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Copyright © 1999 Develcon Electronics Ltd.  All Rights Reserved.