Interface ATM0/3 regained cell

Unanswered Question

Hello all,

I have a 3725 router running IOS version 12.4(15)T9 with 2 VWIC-2MFT-T1 cards connecting to 4 Point-to-Point T1 circuits and configured as a 6MB bundle. I've noticing some packet drops under the ATM/IMA interface and I suspect that the packet drops could be related to the errors that I am seeing in the router logs. I am seeing these errors.

Nov 9 08:34:16.871: %ATM_AIM-5-CELL_ALARM_DOWN: Interface ATM0/3 regained cell


Any ideas what could be causing these errors ? and how to go about fixing it ?

thanks in advance !!!


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Paolo Bevilacqua Mon, 11/09/2009 - 14:24

I think you should have clock source line, not internal.

Then if that's not enough, network-clock-select 1 t1 0/0

Hello Paulo !! Thank you very much for your quick response !!!

These are Point-to-Point T1 circuits, so I have one end sets to Line and other end sets Internal. Service provider does not provide clocking.

Here is what I currently have configured for network clock. Please let me know if I am missing something !!!

network-clock-participate wic 0

network-clock-participate wic 1

network-clock-participate aim 0

Should I remove "network-clock-participate wic" command and add " network-clock-select 1 t1 0/0" command for each T1 ?

Thanks again !!!!


Paolo Bevilacqua Mon, 11/09/2009 - 14:43

How do you know they don't provide clocking ? Sometime they say that, then it turns out that ain't true.

In any case I'd like to see show controllers T1 on the other end before you do anything.

Note with point-to-point T1 you will have better circuit circuit utilization using MLPPP, not ATM/IMA (hideous cell tax overhead).

Paolo Bevilacqua Mon, 11/09/2009 - 15:00


clock source line on both ends, on ISR also network-clock-select 1 T1 (circuit of your choice).

Let us know!

Hello Paolo,

I thought if the clock source is set to Line on one end then the other end must set to Internal for Point-to-Point T1 circuits or the circuit won't come up.

I currently have network clock configured as follow:

network-clock-participate wic 0

network-clock-participate wic 1

network-clock-participate aim 0

Do I remove "network-clock-participate wic" then add "network-clock-select 1 T1" command for each T1 ? and Will it affect production ?

Thanks Paolo !!! I very much appreciate your help !!!


Paolo Bevilacqua Mon, 11/09/2009 - 15:25

Circuits will come up but if no good clock from it, you will have more errors.

With line clock, always leave -participate, add -select with one more circuits. These will need to have different priorities.

Hello Paolo,

I don't quite follow you.

You wrote "With line clock, always leave -participate, add -select with one more circuits. These will need to have different priorities."

Could you please explain in more details ? Basically I have 4 Point-to-Point T1 circuits with clock source configured as Line on side and the other side configured as Internal. Could you tell me how the network clock should be configure for each side ?

Thank you very much !!!


Paolo Bevilacqua Mon, 11/09/2009 - 17:05

No problem, but it's the same that I've told you already:

Even if you have been told that circuit provides no clock, that is kind of unlikely, especially for long spans.

So my recommendation would be to try clock source line under each controller, and configure network-clock-select 1 T1 for one of them.

Paolo Bevilacqua Tue, 11/10/2009 - 09:04

Some platforms do not have these commands at all. On the ones that have, you should always use them.

Hello Paolo,

I was able to change the clock source to Line and point the Network-clock to the T1 controller, but right after I applied the change I started to see a lot of SLIP secs under the T1 controllers so I reversed the changes back and the SLIP secs go away. All seems to work normal now. The one thing that bothers me is that out of the 4 T1 circuits in the bundle, I am seeing some Line code and Path code violations on two of the 4 circuits. Could this be something on the service provider side ? or you still think is something with the clocking ? The other two circuits are clean.

10 Line Code Violations, 7 Path Code Violations.

Thanks Paolo !!! I really appreciate your help !!!


Paolo Bevilacqua Tue, 11/10/2009 - 15:09

That indicate the circuits are actually not providing clock.

This case is not so simple because as you noticed, only some of the circuits exhibit problems.

You can try something else anyway, set clock source internal on the other router, and put back the configuration that has not worked well on the ISR router, check again.


This Discussion