Testing ISDN Backup for 100+ ISDN lines

Unanswered Question
Apr 1st, 2008

We have several branches wherein we use ISDN lines for backup.Currently the testing of ISDN lines is done manually by making a test call after logging into the router.Is there a better method or a script by which automatically every routers ISDN line will be tested and its result would be stored in a file.

I have this problem too.
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Goutam Sanyal Tue, 04/01/2008 - 21:59

Hi Rohan Jhaveri, Can you enter your bedroom without opening the main-door of your house? If then it's not the right way. As per my past experience I had worked with more then 14000 64Kbps leased line and approx the same no of backup with ISDN BRI. Our team till the date - is following the same that you are following. Thanks Goutam

rohan.jhaveri Wed, 04/02/2008 - 23:20

I was rather looking for some creative response like use of cygwin (for scripting) using which at a schedule all the routers would be telneted and a test call would be made.

I can then chk the logs,but telnetting and running test call would be eliminated.

guruprasadr Tue, 04/01/2008 - 22:11

HI Rohan, [Pls Rate if HELPS]

The ISDN circuit can be tested only using a TEST call & during this time you need to monitor for CALL LANDING & clear CALL Disconnection once after the TEST call.

In some situation, the TEST Call may go un - disconnected and it may impact the Primary Circuit also in some other cases the TEST Call may go with problem like, "Frequent Call disconnection, Call vanish after 20 secs, etc.,"

So Manually TESTING will provide better results.

Hope I am Informative.

Pls Rate if HELPS

Best Regards,

Guru Prasad R

Goutam Sanyal Tue, 04/01/2008 - 22:42

Hi Guru Prasad R, I have an experience to work with India's largest Private Network. But never I found "Frequent Call disconnection, Call vanish after 20 secs, etc.," What is that?

Danilo Dy Thu, 04/03/2008 - 07:37

Hi,

I have this problem 6 years ago. The first idea come to my mind is to Ping the remote router ISDN/Dialer Interface IP Address thru ISDN link by my monitoring tool. However, my existing monitoring tool that time is WhatsUp Gold and the maximum polling interval is 1 hour.

There was a monitoring tool similar to WhatsUp (which I forgot the name - I think there is "Brother" something in the product name) that you can configure the polling interval to 1 day. You can also increase the timeout (Since you have to wait for ISDN to dial). This is actually good to test ISDN once a day.

Alternatively, it can be done in PERL Script. Create a script that will ping the ISDN/Dialer Interface IP Address of the remote router and for one that is unsuccessful to send you an email. Run the script once a day in a cron job.

The reason for once a day test is that;

- ISDN start charging when its up

- The reason why ISDN is use as backup is to avoid high cost for a backup link

- To ping the ISDN several times a day (specially international lines) this defeats the purpose of putting the ISDN to save cost.

Regards,

Dandy

Goutam Sanyal Thu, 04/03/2008 - 22:43

Dandy, with that procedure can I analysis the exact reason of outage as well as layer status? pls inform. Goutam

Danilo Dy Thu, 04/03/2008 - 22:51

Hi Guotam,

What do you mean exact reason of outage and layer status?

If you mean the ISDN2, I just want to test the line as in most cases ISDN not able to connect to the remote router because of problem related to TELCO (and not router configuration). Without checking the ISDN line (at least once a day) there is no guarantee that it will connect to the remote router when the primary line (i.e. serial) is down because TELCO does not provide SLA for ISDN2.

I have experienced that ISDN2 cannot connect to remote router not because of configuration problem but TELCO problem - and usually happens when you need them the most (the primary line down during production period).

Regards,

Dandy

Goutam Sanyal Fri, 04/04/2008 - 00:24

Hi Dandy, I do agree with you, but by manually checking I can address the actual cause of the BRI outage. Some times its also not happen if there is some ISDN billing issue. At that case you can dial the ISDN from your site via PRI/BRI and can established the call to communicate but the remote site router will not able to dial your site PRI/BRI for the same. Some times it may issue with last mile that can identify by manually checking also can detect whether it's related with telco or not. And as per my concern secondary link is very important to run a enterprise network. Thanks Goutam

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