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ATM CRC Errors/Slow Speeds

I’m helping a friend out with an ATM issue. User are complaining of slow speeds across the WAN Here’s the setup Adtran Router -> Watch Guard Firewall -> Cisco 2900’s. I’m seeing a lot of CRC errors, tons of runts on the PVC but not seeing any errors on the eth interface of the router? Pings out fine, even with a 5000 buffer. Telnet no problem. The Telco came back with a clean circuit. I’d like to think it’s a duplexing error? But I can’t find a thing to support that theory. To make matters worst I’ve never had to deal with ATM or Adtran Any Idea’s


Re: ATM CRC Errors/Slow Speeds


I would check the ATM shaping rate on the router first and see that it matches the configured PCR/SCR on the ATM circuit.. CRC errors means that you are losing ATM cells somewhere in the middle. It is possible that your shaping parameters are incorrect resulting in drops in the ATM network.

Hope that helps - pls rate the post if it does.


Re: ATM CRC Errors/Slow Speeds

Dear Jhopper1313,

SPecifiy the duplex and speed under the sitch ports that connected to your router & firewall and specify the duplex under the router and firewall interfaces, because the different in speeds may result in packet loss and CRC's, for Ex if the router interface is Ethernet so under the switch port specify duplex full speed 10 etc...

Please rate helpful posts

Best Regards,

Mounir Mohamed