ATM CRC errors

Unanswered Question
Jun 13th, 2008

I have a 7206vxr router with a PA-A3 ATM interface connected by optic fibre to a LS1010 ATM switch. I am getting condsiderable CRC errors on the router interface (receive side), 1000's per hour. We changed the interface on the router, it made no difference. There are about 8 PVC's on the link they are all getting CRC's in ratio with their traffic load.

any suggestions?

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John Patrick Lopez Fri, 06/13/2008 - 05:47

Try to check the settings of your PVC. Check the ABR/VBR-NRT values and see if they are really correct. Maybe your LS1010 ATM switch was configured to a high value. check the show atm vc too.

Joseph W. Doherty Fri, 06/13/2008 - 14:03

Don't quote me on this because it's a very hazy recollection, but I think I recall a situation where PCR for VBR-nrt was slightly under configured by the provider, which caused some cells to be dropped. When the receiving SAR tried to reassemble the IP packet it recorded a hit against CRC for the packet. The insidious issue was this was only seen under full load when the incorrect PCR was occasionally exceeded. Again, can't say it's related to your issue but if using something like VBR, insure PCR is properly configured both on ATM routers and by the ATM provider.

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