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Webcast-Catalyst9k
New Member

Weird Point to Point T1 problem

I have a Strange problem with a point to point T1.

I have a 2610XM (Site A) With 3 WIC-1DSU-T1-V2 Cards in it, Two of thos T1s are point to point T1s to a 1721 on the other end. I am running PPP with MLPP across those T1s.

The problem is that one of the circuits changes state every 2 hours and 16 minutes.

If the circuit is up, it goes down. If it is down it comes back up. This happens EVERY 2:16

While the T1 is down, the Site A interface Shows Down/Down and a remote alarm. The Site B side Shows UP/DOWN.

Any ideas?

Regards,
Steve
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7 REPLIES

Re: Weird Point to Point T1 problem

Hello Steven,

I would check with your service provider first, the interval of 2 hours 16 minutes sounds like there could be something happening on the provider end.

Which IOS versions are you running on your routers ? There is, of course, always a chance that this behaviour is caused by a bug...

Regards,

GNT

New Member

Re: Weird Point to Point T1 problem

the telco has repeatedly said the problem is not theirs.

IOS is 12.3 (10)

Regards,
Steve
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Re: Weird Point to Point T1 problem

Hello,

can you ask your provider to monitor the line from their end as well ? If the line goes down, they must at least be able to see the drops.

If you definitely suspect the problem to be on your side, try to debug the interface with:

debug serial interface

Also, if possible, try to break the multilink configuration, and run the connection over each T1 separately for the interval in which the drops occur, to see if the problem might be related to the multilink, or one of the interface cards.

Here is a handy document for troubleshooting as well:

Troubleshooting Serial Line Problems

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00800a758d.shtml

HTH,

GNT

New Member

Re: Weird Point to Point T1 problem

I have gone through the all the basic troubleshooting. The telco says they see no errors on the line. The only thing they have said is that they cannot loop to the CSU at Site A.

I have a troubleshooting plan in place. I am dealing with maintenance windows and such. I posted here to see if anyone has run into this before.

Thank you.

Regards,
Steve
Please rate all helpful posts.
New Member

Re: Weird Point to Point T1 problem

I have gone through the all the basic troubleshooting. The telco says they see no errors on the line. The only thing they have said is that they cannot loop to the CSU at Site A.

I have a troubleshooting plan in place. I am dealing with maintenance windows and such. I posted here to see if anyone has run into this before.

Thank you.

Regards,
Steve
Please rate all helpful posts.
Green

Re: Weird Point to Point T1 problem

Well, if it actually happens exactly at 2:16:32 (add 32 seconds) that would be 8192 seconds ... a suspicious number, to be sure (i.e., something timing out every 8K seconds).

Watch your smartjack/NIU during that time and see if the state changes (should be some red/yellow/green LEDs on a face panel somewhere).

It sounds more like a bug to me.

Check the ROM rev of the WIC - there were bunches of problems matching up one of the three (four?) ROM versions on the WIC-v2 with one of the flavors of IOS that it would work with (I think the problems spanned a range of 12.{something} through 12.3{something}.

I believe going to a 12.4 version was good for any of the ROM revs for the WIC-v2.

Good Luck

Scott

New Member

Re: Weird Point to Point T1 problem

Did you ever resolve this? I have the exact same issue. 2hrs 17min up, then down...round the clock.

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