T1 errors on a 2911, not 2811

[billmatthews]

For about 6 months we've had a 2811 with Version 15.1(4)M1 with a T1 card.  No errors on the line.  Then we swapped to a 2911 running 15.2(4)M3.  We took the existing T1 card from the 2811 and just moved it into the 2911. 

After the 2911 swap we started experiencing a lot of CRC errors on the line.  We asked our provider to test the T1, no problems.  We swapped T1 cards with a new one, no change (still lots of CRC errors).  We moved back to the 2811 (moved the T1 card again) -- no more errors.

Anything I should investigate? The only differences is the hardware (2811 vs 2911) and a small IOS change.

[vmiller]

CRC's usually imply a physical layer issue.

I would go through the card configuration, make sure its set up correctly.

Insure that the clock source is set to line.

Verify that the cable from the router to the Carrier network interface is correct.

[stephen.stack]

CRCs do indeed point to a physical layer issue. As you have moved the card recently. Reseat the card first. Check cabling for damaged pins etc. Then get in touch with carrier.

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