[OT] help T1 connection Cisco and Adtran Atlas 550

Unanswered Question
Jun 17th, 2007

Hi folks,

I've a problem to connect my Cisco with cT1 PRI and Adtran Atlas 550 with T1-PRI network card. The connection doesn't work, the controller is down, and the Adtran module in Alarm. I've already check cable and modules, all at L1 is ok. The Adtran simulator is configured as Cisco Academy, but maybe I've made a mistake. Anyone could help me?

this is the controller T1 output:

R1#sh controllers t1

T1 1/0 is down.

Applique type is Channelized T1

Cablelength is short 133

Transmitter is sending remote alarm.

Receiver has loss of signal.

alarm-trigger is not set

Soaking time: 3, Clearance time: 10

AIS State:Clear LOS State:Clear LOF State:Clear

Framing is ESF, Line Code is B8ZS, Clock Source is Line.

Data in current interval (507 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 507 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 507 Unavail Secs

the Cisco configuration is quite simple:


isdn switch-type primary-ni


controller T1 1/0

framing esf

linecode b8zs

pri-group timeslots 1-24


The Adtran simulator says:

T1 Alarms LOS[*] RED[*] YELLOW[-] BLUE[-] DS0 Alarm[*]

Rx Level -22.5 dB

and I receive a lot of 'Severely Errored Frame Secs'

I'm not experienced on T1 connections, so please help me to understand when the problem is ... Any advice will be appreciated.

Thanks for your support



I have this problem too.
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Edison Ortiz Sun, 06/17/2007 - 07:30

What device is supplying the clocking ?

Usually, you leave the DSU for clocking on the line since the telco provides it but on this case (not sure about your setup), it sounds like this is a p-t-p setup with no telco involved, therefore one of the devices must supply the clocking.

ariela Sun, 06/17/2007 - 07:46

yes, maybe is a clock issue ... but I don't know where setup the clock on Adtran simulator ...

On Cisco output the clock source is "line", so I think this is like a DTE, it's waiting for a clock, correct?


ariela Sun, 06/17/2007 - 08:12

Ok, I've found the Adtran Timing configuration:

Primary Timing Source: INTERNAL

Backup Timing Source: INTERNAL

HTH to found my issue



ariela Sun, 06/17/2007 - 08:17

I've already tried Cisco clock INTERNAL and Adtran cock T1-PRI, without any luck :(

Any advice will be appreciated


Paolo Bevilacqua Sun, 06/17/2007 - 08:58


Can you tell us how did you made the cable exactly? Which pairs are crossed and stuff like that.

Edison Ortiz Sun, 06/17/2007 - 09:34

I'm not sure about the Adtran simulator but on the Cisco side, you can find out if your end is DCE or DTE by issuing:

show controllers s1/0 | i DTE|DCE

Edison Ortiz Sun, 06/17/2007 - 10:18

I believe you mean 'this is an internal CSU' as you still use DTE|DCE on a T1. The DTE|DCE characteristic is determined by the external serial cable.

I overlooked the internal CSU configuration here and for that I'm sorry.

Paolo Bevilacqua Sun, 06/17/2007 - 10:47

Hi Edison,

There is no DTE/DCE serial cable on T1 / E1.

There is no DTE/DCE information when doing "show controllers" on a T1 / E1 serial interface. In fact, there is no information about the cable, at all.

Edison Ortiz Sun, 06/17/2007 - 11:38

This output was obtained from one of my WAN routers. This router is connected to an ADTRAN CSU/DSU via DTE serial cables.

sh controllers | i DTE|DCE|Serial

Serial Param Reg= 0x218823 Hash table pointer= 0xF69A940

Serial 0 mask 30000F3Serial 0 cause 0

Interface Serial0/0

DTE V.35 TX and RX clocks detected.

Serial Param Reg= 0x218823 Hash table pointer= 0xF7ACB80

Serial 0 mask 30000F3Serial 0 cause 0

Interface Serial0/1

DTE V.35 TX and RX clocks detected.

rmd(F8D9180): nbd F8D9190 cmd_sts 80800000 buf_sz 06000000 buf_ptr F8DCE48

Interface Serial1/0

DTE V.35 TX and RX clocks detected.

Interface Serial1/1

DTE V.35 TX and RX clocks detected.

Interface Serial1/2

DTE V.35 TX and RX clocks detected.

Interface Serial1/3

If the OP was connected to an external CSU/DSU, regardless of the speed (T1|E1|DS3), he will see the DTE|DCE information depending upon the cable.

You won't see this information if the router has an internal CSU/DSU.

EDIT: P.S. I see where the confusion is. As seen in the original post, the controller T1 won't provide this information. The controller T1 is simply a point of reference to the internal module in the router device. It doesn't reflect how a T1 relies on the clocking DCE|DTE.

Paolo Bevilacqua Sun, 06/17/2007 - 11:51

Hi Edison,

the interfaces that you took for example, are serial interfaces, not T1 or E1. These have the smart serial connector, that then becomes V.35 or other type, DTE or DCE, depending on the cable attached.

The T1 / E1 interfaces have an RJ45 connector. Older types, have a DB-15 connector. All channelized and digital voice interfaces are of this type. On these, there is no concept like DTE or DCE.

Hope you can agree on that :)

Edison Ortiz Sun, 06/17/2007 - 12:37

Gosh, I can't believe you can't see what I'm trying to say. I've agreed with you from my first post but you don't see it.

When you corrected me, you said

"Edison, this is a T1, there is no thing such as DCE / DTE in T1 / E1."

If you were to add something like:

Edison, this is a T1 *controller*, there is no thing such as DCE / DTE in T1 / E1 *controller*.

The two sentences have a HUGE difference and that's my argument. If you can't see it, I digress.

We could've saved some precious bandwidth.

Paolo Bevilacqua Sun, 06/17/2007 - 12:55


No worries. The point I was trying to make is that there is no DCE / DTE concept in T1 / E1 technology even if cisco and their controllers did not ever existed. So, I actually claim that both sentences above are correct.

Since I don't think to be wrong in that, I see no malice in trying to get it across in an open forum.

ariela Mon, 06/18/2007 - 02:13

Hi Paolo, hi all,

thanks for your support.

Well, on Cisco router I've a cT1-PRI (DB connector) directly connected to Adtran Atlas 550 (RJ45 connector) with a E1 Cable (that is physically the same as T1, correct?)

Any advice will be appreciated



Paolo Bevilacqua Mon, 06/18/2007 - 02:16

Hello Ariela,

Can you get the pinout for the Adtran please ? So we can compare to the cisco E1 cable.

I don't think it's the same, else it would be working :)

Paolo Bevilacqua Mon, 06/18/2007 - 02:56


Very likely TX and RX pairs have to be swapped.

Cisco made two versions of that cable, CAB-E1-PRI/TE and CAB-E1-PRI/NT. To add confusion, the pinout listed at:


is wrong, because the two version are listed with identical pinout!

Anyway, find the method that you like better to swap pairs on pin 1-2 and 4-5, and the link should go up!

ariela Mon, 06/18/2007 - 04:15

Hi Paolo,

thanks for your answer.

When could I find the correct pinout for Cisco cT1-PRI module?

In your opinion, I've to swap pair 1-2 with 4-5?



Paolo Bevilacqua Mon, 06/18/2007 - 08:56

Hi Andrea, for the module itself, the pinout is on the document I've linked before. In fact, you could also build a db-15 to db-15 cable. But, I think it easier to swap pin 1-2 to 4-5 recrimping the cable you have.


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