Line Code Violations, Path Code Violations

Unanswered Question
Aug 24th, 2006

We been seeing tons of Line Code Violations and Path Code Violations on our T1 (frame relay). Telco has tested the circuit a few times, it's clean. Telco says we are getting hit with tons of traffic causing the Line Code Violations and Path Code Violations.

We have replaced the cabling and T1 card.

Also, whenever this happens, the router stops responding and we have to reboot it. It has happened a few times and at the same time.


I have this problem too.
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sundar.palaniappan Thu, 08/24/2006 - 17:50


Is the line code (b8zs/ami) consistent with the provider setting. I doubt excessive traffic is causing the LCV and PCV as this is normally a result of physical layer problems.

With loopback testing you could isolate the trouble whether it's on the CPE or circuit. You can do software/hardware loopback tests but hardware loopback tests are more accurate. This link should help with you loopback testing.

Hope that helps!



alex@bmchp Mon, 08/28/2006 - 13:47

I'm having this same issue on 2 separate routers on 2 separate circuits. They are both Verizon circuits. I have spoken with a couple techs, they don't seems to know excatly what the settings on the controller should be.

2800-test#sh controllers t1 0/0/0

T1 0/0/0 is up.

Applique type is Channelized T1

Cablelength is long gain36 0db

No alarms detected.

alarm-trigger is not set

Version info Firmware: 20040202, FPGA: 11

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

CRC Threshold is 320. Reported from firmware is 320.

Data in current interval (507 seconds elapsed):

156 Line Code Violations, 155 Path Code Violations

0 Slip Secs, 0 Fr Loss Secs, 147 Line Err Secs, 8 Degraded Mins

148 Errored Secs, 4 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs




Total Data (last 33 15 minute intervals):

51478 Line Code Violations, 50727 Path Code Violations,

0 Slip Secs, 0 Fr Loss Secs, 18998 Line Err Secs, 495 Degraded Mins,

19032 Errored Secs, 11317 Bursty Err Secs, 1 Severely Err Secs, 0 Unavail Secs


jackyoung Mon, 08/28/2006 - 17:38

Check below troubleshooting guide for T1 :

Did you (and the SP) confirm the line code is correct ? Please try to change to "ami" and test again.

There is another field notice for T1 Line code. Please check below. If you hit the case (long haul cable), try the command.

Hope this helps.

pciaccio Tue, 08/29/2006 - 02:45

Usually violations are related to the coding of the T-1. example: Bipolar violations are that you are receiving violations with regards to the coding (B8ZS or AMI) in that either you have a miscoded line or errors on the line that caused the violation. In reference to the Line and Path violations, the line violations are reference to your local loop to your first DACs point. That is where your coding is either generated or passed along from your carrier (dependant on how you are provisioned for the T-1). The Path is the whole length of the T-1 line from point A to Point Z. If you are receiving Line errors then your issue is from you to your first DACs point. If Path errors then the issue lies anywhere within the path of the T-1 line from A to Z. My quess from your errors is that you may have a miscoded T-1 line. Possibly you may have AMI coding somewhere down the path... You can isolate this by placing a BERT tester on the line and run a 2:8 pattern which will pass then run a 1:7 pattern which will invoke B8ZS. If any point is mismatched then you will get errors on the line from the 1:7 pattern. From that point you need to isolate further..Good Luck...

jackyoung Tue, 08/29/2006 - 16:44

Thanks a lot. Phil. This is very useful information but require PPT assitance and equipment for the testing. :)


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