sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Loop Stuck in NIU

We provide a Point to Point T1 for one of our Cust. and of course we go through a LEC and they provide the T1 with the NIU at the Cust Prem. Your usual Point to Point. Well once a month this damn NIU seems to get a loop stuck in it and I have the LEC take a look at it and of course we can both take down the loop VIA the DACS. Im just wondering what could be making this just pop up. Is the NIU faulty? Could it be the Cust equip. creating some kind of loop UP code? Its a WESTEL NIU from what Im told. Let me know if you need more info or if this doesnt make sense, we're having a fiber outage at this time and my head hurts so I may not be making any sense. Thanks In advance!

Welcome. I know of nothing other than a defective NI that would cause this to go into loop back, I would think if it happens that often the LEC would have replaced it by now. I suppose it's possible the customer could be putting a test set on it and looping the far end and forgetting to take it down, but I doubt it. I doubt even more the customer equipment putting out a loop up code. Who do you work for in Austin? Send me a PM if you don't want to post it, I worked for AT&T there for about 10 years.

There really are a number of possibilities with this…

* Faulty NIU, is possible.
* There “shouldn’t” be anything in the customers data stream that would put it to loop-back but it does happen.
* How is the NIU powered??? Line or local? If it’s local is there some event that effects to power once a month or so. It would make the remote testers think the circuit was taken down intentionally by the end-user.


Post what Westell unit is it… That may help narrow it down some too.

I'd be more inclined to think someone has an auto test scheduled that's doing this. I've never seen a customer signal do it Bryan, so that's a new one for me.

Thanks for all the replies!!! I work in a 24X7 NOC so unfortunately I didnt get to work this ticket to the end, But here's what the notes said.....there may be misoptioning on the NIU which causes it to go into loop back and not ALL1's state when it looses sync with the CPE.Ever heard of that?

No, but it would sure be easy to check. Break the circuit momentarily and see what happens. Now if this is one of the new NI's that report data to you like a CSU does, it maybe it's misoptioned and going into loop on an all 1's. That I've heard of, but have never seen personally.

Might have someone look at the CPE's on each end. They could have remote loopbacks enabled. If you RLB disabled on each end that would eliminate the CPE and point toward the NIU's T-1 card. I would have the service provider change positions in the NIU's and change cards.