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New Member

Timing issue?

I have a point-to-point T1 between sites in TX and NC and they are having an issue I think may be timing related but I'm not sure. I don't know how to view the interface to see what the timing is set as. Both sites have 1700 series routers with WIC-1DSU-T1 cards in them. When I ping from one to the other I get 3 or 4 out of 5 responses but rarely all 5.

Any help would be appreciated.

Hall of Fame Super Gold

Re: Timing issue?

Do show interface and you will probably see errors, like CRC, aborts. Do show controllers and you will see clock information among other things.

Call telco and ask to confirm they are providing clock both sites as normal on long distance T1.

Independently from the answer, try setting one interface to clock internal.

If the above doesn't help you need to open a ticket against the circuit.

Hope this helps, please rate post if it does!

New Member

Re: Timing issue?

I do seem to have a lot of errors:

Received 379569 broadcasts, 0 runts, 3 giants, 0 throttles

2828084 input errors, 747718 CRC, 1249596 frame, 0 overrun, 0 ignored, 830770 abort

15888456 packets output, 1559182872 bytes, 0 underruns

I did set timing one one side to internal and the other to line but it didn't seem to help.

Hall of Fame Super Gold

Re: Timing issue?

To do things neatly on your end, check cabling from router to telco termination. Must NOT be ethernet patch cable but T1 that as a different twisting.

Also check that you are using AMI and ESF or what the provider has told you.

New Member

Re: Timing issue?

The following is the only thing I can find with the information:

interface Serial1

description TO NC Circuit ID xxxxxxxxxxx

ip address

service-module t1 clock source internal

I think the rest must just be default. This just started happening this afternoon so I don't think it would be because I didn't have something configured right as they have been working fine for months.

New Member

Re: Timing issue?

It must have been a line issue because after I placed the trouble ticket with the Telco it is working fine. As usual they are stating they didn't do anything on their end because there was nothing wrong that they could see.

Thanks for the help!

Hall of Fame Super Gold

Re: Timing issue?


Many things can happen without the telco rep knowing, unless it is a major issue. A repeater box can overheat and things like that. Then they fix it and unless it impacts you SLA you are never told.

Be aware the internal clock is not the way it is supposed to be, so do clear counters and check for errors over time.

Thanks for the nice rating and good luck!