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Stevenson Ranch, CA

[Config] Alarm light on 2621 T1 WIC

Good afternoon all,

I am having some very frustrating issues with connectivity to our ISP - SBC in Los Angeles.

This is a new circuit and has not yet "worked." A week ago Monday an SBC tech checked out the router programming and stated it was set. However communication was not functioning and the tech could not telnet into the router, even though both interfaces (Ethernet and Serial) were up. So, a provisioning tech performed a "Shut / No Shut" on the line and was then able to connect the router via telnet and login.

We did not try further connectivity as the project was scheduled to move forward in a week. However, on Friday (a week ago) SBC called and said that they had detected connectivity to our router bouncing up and down. When I came in to check it out, the AL light on the DSU/CSU module was pegged on. In investigating, the serial interface was down according to the telnet interface. Again, SBC techs walked me through some steps and troubleshot the line with no problems found - other than not being able to connect to our router. They also checked our router config and saw nothing wrong there. Then they dispatched a tech for on-site work. The tech declared that the line was okay up to the biscuit.

I proceeded to program another 2600 series router (using the Cicso GUI programming interface as I am not Cisco savvy) and got the same issue - AL light on and no connectivity. We have changed cables too without success.

They now tell us that we need to buy one of their 1700 series routers or but a $1000 service contract with them so that they will fix it.

My question is, why did it "work" for 4 days (no AL and SBC could telnet in) and then just stop working? Doesn't the AL light usually indicate a lower level issue than a mis-configured router? And, if the router is mis-configured, why did it work earlier? I believe that the issue lies elsewhere but no one at SBC will listen and I do not know how to verify/test/prove it... Or, is there a troubleshooting method that I should use to see if it an issue on my side?

Thanks for helping - any pointers would be much appreciated.


Merrimack, NH
Without knowing your config and everything else, it sounds like a line issue if it was working then stopped. The only way to troubleshoot T1 problems is to connect a T-Bird analyzer, period.

However, Cisco has some T1 troubleshooting tips here:


If you do a search on CCO for "T1, troubleshooting" there are more. (Note the comma)

I would tell them that if they connect the 1700 and it does the same thing without them touching the other end then you'll buy it. Otherwise they eat it. Too bad it wasn't Verizon. Used to work there in Southern Cal and know a few people.


There are 10 types of people, those that understand binary, and those that don't.

Tampa, FL
·Verizon FiOS
reply to john2060
The next time you an issue, call sbc back while the alarm light is on and ask them to "loop the smartjack". As a previous poster mentioned, they use equipment called a TBird.

The smartjack most likely is a box installed inside your building probably close to the router. Follow the cable from your router and you'll find the smartjack. The smartjack is sbc's termination point. Anything after the smartjack is not there responsibility (unless you have some other agreement).

If they can loop the jack while your alarm light is on I would say the problem is on your end, probably a bad T1 card (wic-1dsu-t1).

you could do a 'show diag' on the router console to see if it reports anything. If you need a T1 card, they can typically be purchased of ebay for around $130.


Chicago, IL

4 edits
reply to john2060
You could also ask them to loop something (mux, etc) towards your end and cut it through to you. If your interface comes up looped, you know you are good to that point. Another thing to try is to have them cut the circuit and monitor to your side, manually loop your CSU and see if they can monitor and run patterns to your loop.

The real problem here is that they are probably just running an autotest which reports no trouble found. You need to work with a tester, and request an assist test.

Also, it is highly unlikely that they are using a T-BERD to test with you, that only happens when they dispatch out to the CO. MOST circuits these days have remote access and don't require someone manually looping things, although sometimes it is still helpful to have eyes and hands in the field.

Trouble shooting a broken circuit without a good tester is hard, especially since I assume you don't have the circuit detail, and probably not much experience dealing with them. Sometimes you really need to hold their hand to make them find the problem.


Stevenson Ranch, CA
Thank you all -

This information was helpful and I will proceed with "forcing" some greater help from SBC on Monday.

I appreciate your time!

Hilliard, OH
Not sure on your status, but more information on
your setup would greatly help. I deal with SBC
and the other baby bells Verizon, Altel, GTE, and
a bunch of others including local private telco's where
you have a hard time getting anything done during
planting and harvesting time since the telco workers
are farmers and that takes priority, its nuts, but
sorry for digressing.

What type of cirucit it is it;

Full T-1 ?
Line encoding (ESF/B8ZS) or SF/AMI or etc ??

Is this an extended Dmarc? (ie do you plug into the
smartjack com cabinet or do you plug into a biscut
jack that extends the circuit from another part of
the building.

what type of errors are you seing on the serial interface?

is this a single wic (ie wic-1dsu-t1) or some
other wic like a vwic-2mft-t1 (dual channelized T-1 wic) ?

serial interface encapsulation (HDLC/PPP/etc),

what testing has SBC done?

I've had 4 circuits in the past week that the telco
has said tested clean every time they tested it.

I finally asked for a conference call, which is 2
steps below circuit re-engineering. Working work
the tech, I had him break the circuit in the various
C.O.'s that the T-1 went through, each time
they didnt see any errors, but on my interface I saw
errors ramping up in the thousands. The last time the
put the circuit back together, they finally saw the errors
I was seeing. The issued turned out to be a bad smartjack
on the "Z" side of the circuit. Smartjack was replaced
and all is well and happy.

If they didnt find any errors, I would have called for a
Class "A" test where they have one tech at the "A" end and
one tech at the "Z" end, both with Tbird's runing head-to-head tests.

The final and most unwanted step if the Class "A" doesnt
show anything, is to force them to re-engineer the circuit.
We've had to have them do this maybe about 10 times in
the past 8 years.

back to the Wic.. the reason I ask if it's a wic-1dsu-t1
or a vwic-2mft-t1, is that if you use the vwic and use
the standard configuration, you'll have 56k channel speeds.
We always have to change this to 64k speeds to get the circuit to come up. Only a few sites we've had to use
the 56k channel speed assignment.

Let me know what you've found out, I've seen all sorts of issues, including one thats pretty much taken the cake.

We had a site that had 15 T-1s installed, and they were
doing constuction around the area. The weight of the
construction equipment had caused a conduit carring the
T-1's and normal voice circuits to be crushed. During
the day when the constuction equipment and local traffic
passing over the road, caused all sorts of errors on
the T-1's and the voice lines. BUT at night when the telco
was testing the circuit, there was light traffic, and
NO errors were found. We finally had soo many errors
one day, that we had them take the circuit in the middle
of the day, that's how we finally found out what was going

Grand Rapids, MI
reply to john2060
My guess is your smartjack went bad and the card inside is having problems.

I have see similar issues. Call teleco ask them to run a test to the smartjack and run patterns against it for a good 15 mins and see if it shows any errors.

next thing to do is make sure you plug the T1 wic directly into the smart jack and get rid of any extensions you might have between ya.

If after that point borrow another WIC, Call cisco TAC or a CSU/DSU to test the smartjack out..

sometimes having spare gear can prove your point that its not your problem because its rare to have two bad pieces of equipment. Especially if something works fine somewhere else on some other line.