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New Member

Not sure what to do next

I am having a problem with a T1 line I just installed. I just turned up an additional T1 on a 3640 running 12.2-10b. The new T1 is working flawlessly, however, the old T1 line is having problems:

Serial0/1 is up, line protocol is down

Hardware is DSCC4 with integrated T1 CSU/DSU

Internet address is

MTU 1500 bytes, BW 2048 Kbit, DLY 20000 usec,

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

Encapsulation HDLC, loopback not set

Keepalive set (10 sec)

Last input never, output 00:00:08, output hang never

Last clearing of "show interface" counters never

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

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/1/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1536 kilobits/sec

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 1512 giants, 0 throttles

609417 input errors, 85324 CRC, 524093 frame, 0 overrun, 0 ignored, 0 abort

28355 packets output, 681000 bytes, 0 underruns

0 output errors, 0 collisions, 9463 interface resets

0 output buffer failures, 0 output buffers swapped out

3 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

This interface is connected to a 3662 WIC-1DSU-T1 line card. I had the telco test the line and they said they dont see a problem with the line.

The problem I see during a debug is the seqnum myseen yourseen is not in sync. I tried to following things to troubleshoot and fix the problem:

1. changed the line timing from internal to line

2. changed the data-coding from normal to inverted

3. installed another WIC-1DSU-T1in a separate module (problem still occurs)

I'm not sure what to do next, any thoughts would be appreciated.

New Member

Re: Not sure what to do next

What prot are you running over the old T1, Is it frame? if so and if not done already you may want to have telco run a test PVC, "The line protocol is down" indicates no protocal detected. May be a PVC issue. Also make sure that your router is running the same protocal as the telco company e.g. Cisco or ANSI

Hope this may help... Steve

Re: Not sure what to do next

1) Do a show controller T1, does it show either:

"Receiver has loss of frame" or "Receiver has loss of signal"

Loss of frame is framing mismatch or cable length issue.

Loss of signal is usually physical (cable, connector etc).

Are their any other errors?

2) Put interface into loopback and do a debug serial interface (does keepalive counter increase, if yes problem is not router - get your provider to test again. If doesn't increase problem is hardware on router)

Is encap (HDLC) correct? Your Bandwidth is set to 2048, change to T1. Your clock source is probably line (usually is).

Hope it helps.



Re: Not sure what to do next

do a sh service-module this will give you stats such as OOF line errors alarms. Work with the carrier using loopbacks to isolate the problem. make sure you are ESF and b8zs , another thing is check with the carrier and find out who is providing clock , If they are set your source on both sides to network , if they are not 1 of your routers needs to be set to internal and the other needs to be set to network or line

New Member

Re: Not sure what to do next

The problem that I see are all the errors on line.

609417 input errors, 85324 CRC, 524093 frame

These errors typically come from the carrier and can be caused by a bad smart jack, mis match in framing or coding or a dirty dax.

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