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NM T3 does not detect T3 line

Hi all,

We are trying to replace a external adtran (t3su) and HSSI Card with a NM T3 card (with builtin T3SU). When we move the circuit over to NM T3 card from external adtran for some reason it does not see the circuit and interface and controller stays down down.

We have verified all the settings with carrier several time CRC32, LINECODE, CLOCK SOURCE, SCRAMBLING, DSU MODE etc. and all these settings are correct. The weird thing is that circuit is working fine with external ADTRAN (T3SU). We are already working with Cisco to look into this issue. We are having this issue in more than one sites so its very less likely possible that its hardware issue. Cisco is suggesting to use the attenuators , as per them may be signal strength is too high or too low for the NM T3 card that its showing down down. But incase of attenuation issue you would mostly see LCV Errors , in our case error counter is zero, but funny thing is all LCDs are green.

I would appreciate if anyone can advise something in this scenario. Please let me know if anyone has seen or heard of this type of issue before.




paolo bevilacqua
Hall of Fame Master

Can you send a show controllers T3? Ideally you would have to try attentuators, too.

The following is the output of controller command for one of the site

rus-wan01-3745#sh contro t3 4/0
T3 4/0 is down.
  Applique type is Subrate T3
  Receiver has remote alarm.
  MDL transmission is disabled
  FEAC code received: DS3 AIS Received
  Framing is C-BIT Parity, Line Code is B3ZS, Clock Source is Internal
  Data in current interval (220 seconds elapsed):
     1 Line Code Violations, 1 P-bit Coding Violation
     0 C-bit Coding Violation, 0 P-bit Err Secs
     0 P-bit Severely Err Secs, 0 Severely Err Framing Secs
     220 Unavailable Secs, 0 Line Errored Secs
     0 C-bit Errored Secs, 0 C-bit Severely Errored Secs

Yes thats what we are planning to do, i have verified settings with carrier thousand times. Another possibility is bad batch of NM T3 cards, but the NM Cards that we were trying to install, we tested those cards in LAB with cisco and we were able to self loop those cards. If a card is seeing a loop then i guess its not a card issue.

My only concern is that if its signal strength issue then we should see LCV errors in the controller output that we are not seeing. But as per cisco sometimes if signal strenght is too high , LCV counter does not increase. Please let me know if you think there is anything else that we should verify.

Thanks for the response.



Receiver has remote alarm.

This means the remote is receveing signal from this router with errors, or not at all.

It would be useful to see show controller T3 on the other side too
FEAC code received: DS3 AIS Received

Same as above

Framing is C-BIT Parity, Line Code is B3ZS, Clock Source is Internal

Clock should be Line

You may want to try an attenuator on i'face TX.

"You may want to try an attenuator on i'face TX."

Well thing is i checked with carrier as well , neither they are seeing my equipment nor my router is seeing their equipment.

And i personally think that installing attenuator on TX of router wont make sense. Usually the "cable length" command under controller interface defines the distance of router from MUX and router automatically adjusts its transmit according to the cable length.

I think it would be more appropriate to install attentuator on the cable that connects to recieve interface of router to decrease the signal strength of signals coming from MUX.

I have a migration scheduled on 17th , lets see what happens man i will have carrier and vendor (cisco) online with me and carrier technician on site.

Lets keep our fingers crossed.

Feel free to share any thoughts , will keep checking this thread till migration.