ATM CRC Errors

Unanswered Question
Mar 27th, 2007


We have a 2600 Router that uses ATM and is connected via T1 line to a Fore ASX1200 at our main site.

We experience terrible slowdowns during the day and downloads will often time out. We've tried unplugging everything and just plugging the router into a switch with one PC. We still have the same problem.

When I did a 'show interfaces' the other day, I noticed the ATM interface had 260,000 CRC errors. The last time it had been reboot was 8 weeks ago. That seemed like too many to me.

Can someone point me in the proper direction for troubleshooting this? I've attached some outputs from show commands as well as the running config. I've cleared the CRC Counters, that's why they're not high in the text files.

Any help is greatly appreciated.


I have this problem too.
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chantman06 Tue, 03/27/2007 - 11:05

I don't receive any output when I do show controller t1. I think the T1 is first ran through a ATM Switch.

Anyways, I've attached the output of 'show controller atm 1/0'



Paolo Bevilacqua Tue, 03/27/2007 - 13:27


you have of the little-used ATM 25 modules that likely connect to likely to adsl modem or a switch. The T1 may have problems but must be diagnosed for the Fore DSU unit, the router cannot. Check cabling and clock on both sides.

Newer routers can connect directly to the ATM T1 also.

Hope this helps, please rate all useful posts!


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