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New Member

Path Code Violations

We're having trouble with a number of T1's(7 in all) showing excessive Path Code Violations. These lines are delivered via a DS3 and broken out with an Adtran MX2800. The DS3 and the individual T's have been tested by the telco and are clean. The far end of these T's are not showing any errors. So my question is given that these T's are deliverd via a local loop DS3 how sould the individual serial interfaces be configure for clock timing?

Any advice would be greatly appriciated!!

Router is 7206VXR Version 12.2(15)T14.

Port 4 is a PA-4T1.

- Todd

T1 4/2 is up.

Applique type is Channelized T1

Cablelength is short 133

No alarms detected.

alarm-trigger is not set

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

Data in current interval (467 seconds elapsed):

0 Line Code Violations, 467 Path Code Violations

0 Slip Secs, 1 Fr Loss Secs, 0 Line Err Secs, 2 Degraded Mins

100 Errored Secs, 60 Bursty Err Secs, 1 Severely Err Secs, 0 Unavail Secs

Total Data (last 24 hours)

0 Line Code Violations, 37846 Path Code Violations,

0 Slip Secs, 10 Fr Loss Secs, 0 Line Err Secs, 87 Degraded Mins,

4480 Errored Secs, 3765 Bursty Err Secs, 10 Severely Err Secs, 0 Unavail Secs

T1 4/3 is up.

Applique type is Channelized T1

Cablelength is short 133

No alarms detected.

alarm-trigger is not set

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

Data in current interval (467 seconds elapsed):

0 Line Code Violations, 119 Path Code Violations

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

43 Errored Secs, 27 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Total Data (last 24 hours)

0 Line Code Violations, 10759 Path Code Violations,

0 Slip Secs, 7 Fr Loss Secs, 0 Line Err Secs, 52 Degraded Mins,

2728 Errored Secs, 1757 Bursty Err Secs, 7 Severely Err Secs, 0 Unavail Secs

13 REPLIES
Silver

Re: Path Code Violations

Hi ,

Can you paste the config of the router ?

Thanks,

satish

New Member

Re: Path Code Violations

Here are the controller and port configs.

- Todd

controller T1 4/2

framing esf

clock source internal

linecode b8zs

channel-group 0 timeslots 1-24

!

controller T1 4/3

framing esf

clock source internal

linecode b8zs

channel-group 0 timeslots 1-24

interface Serial4/2:0

no ip address

encapsulation ppp

no fair-queue

ppp multilink

multilink-group 1

!

interface Serial4/3:0

no ip address

encapsulation ppp

no fair-queue

ppp multilink

multilink-group 1

interface Multilink1

ip address ---.---.---.--- 255.255.255.252

ppp multilink

multilink-group 1

New Member

Re: Path Code Violations

Can you paste the remote controller/port configs? I've seen IOS bugs w/ certain Port Adapters that falsely increment the PCV counters, however with that particular bug the LCV's incremented as well.

New Member

Re: Path Code Violations

Actually the remote sites vary in type. All are Cisco routers, some with integrated CSU/DSU some with external Adtran TSU. The only common aspect is that the other ends are not showing any PCV/LVC or serial interface errors. The only errors I see are on the 7206 from lines coming from our local loop DS3.

Whats confusing me is PVC with no LVC... I have not found any references to this type of situation.

Any additional suggestions would be greatly appriciated.

- Todd

Silver

Re: Path Code Violations

Hi ,

What is the status of serial interfaces ?

Thanks,

satish

New Member

Re: Path Code Violations

I should note that these two interfaces are setup for Multilink PPP but other interface setup for simple HDLC are show the same problems with PCV errors.

Here is the current status for the two interfaces:

peru-gw1#sh int s 4/2:0

Serial4/2:0 is up, line protocol is up

Hardware is Multichannel T1

MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,

reliability 255/255, txload 9/255, rxload 1/255

Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-inverted

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 07:03:04

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 10000 bits/sec, 18 packets/sec

5 minute output rate 60000 bits/sec, 33 packets/sec

3358045 packets input, 392933056 bytes, 0 no buffer

Received 0 broadcasts, 47350 runts, 0 giants, 0 throttles

51565 input errors, 3122 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort

4051567 packets output, 440113097 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

no alarm present

Timeslot(s) Used:1-24, subrate: 64Kb/s, transmit delay is 0 flags

peru-gw1#sh int s 4/3:0

Serial4/3:0 is up, line protocol is up

Hardware is Multichannel T1

MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,

reliability 255/255, txload 6/255, rxload 1/255

Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-inverted

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 07:04:44

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 8000 bits/sec, 16 packets/sec

5 minute output rate 41000 bits/sec, 22 packets/sec

3360519 packets input, 393350480 bytes, 0 no buffer

Received 0 broadcasts, 4859 runts, 0 giants, 0 throttles

7511 input errors, 2064 CRC, 0 frame, 0 overrun, 0 ignored, 122 abort

4054860 packets output, 440975814 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

no alarm present

Timeslot(s) Used:1-24, subrate: 64Kb/s, transmit delay is 0 flags

Re: Path Code Violations

As you were able to isolate the problem to the local loop on the DS3 side the problem appears to be on a common hardware all these T1s share. Since telco testing didn't see any errors, problem could very well be the Adtran. Have you tried power cycling the Adtran or even better if you can swap the Adtran and check the status?

HTH

Sundar

New Member

Re: Path Code Violations

Have not tried powercycling the Adtran yet. Actually, am scheduled to do testing on that unit Thursday. It has redundant controllers so I'm going to swap over to the backup controller and let it run for a few days.

Blue

Re: Path Code Violations

No slips, so your clocking is good. No line code violations so the line code config is correct.

In my experience path code violations (though you usually see some line code errors) are cabling issues. What kind of cable are you using between the mux and the router? How long is the run?

With multiple T1s, running them all in a single cable can cause cross talk problems. Telco best practice is to use shielded 110ohm T1 cable, and run all TX pairs in one cable, and all RX pairs in another. Shields should be grounded on one end only. Another way is to run individual T1s in single Cat5 cables.

For troubleshooting maybe you could run a temporary cable for one T1.

Please rate helpful posts.

New Member

Re: Path Code Violations

Thanks for the info!

The MUX is in the same rack as the router. I'm using Cat5 for each T1 coming out of the MUX. Most cable are only 18 inches. Could the cables be too short?

- Todd

New Member

Re: Path Code Violations

18 inches shouldn't be a problem, but you could try changing the line build-out by issuing "cablelength short" command under the controllers. I have around 15 T1's all using 48 inch Cat5e cables w/ no problems.

Blue

Re: Path Code Violations

I would replace one of the cables on an errored T1 with a known good cable, Ideally one that has only pins 1,2,4,5 wired. T1s are very robust, and on short cables will often run with one wire broken, though with high error rates -- much like your problem.

Silver

Re: Path Code Violations

Check below link for info. (You may read it before).

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00801095a3.shtml

I suggest to replace the cable and test again.

Hope this helps.

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