10Gbps Interface from Carrier is Causing Input errors and CRC errors

Env: Cisco Nexus 9508 with an 10Gbase-LR SFP connecting to the carrier. For the last few days the interface has been racking up input errors and CRC. Hundreds ever few seconds. We've replaced the SFP and we replaced the fiber from the SFP to the patch panel.

What trouble-shooting methods do I have my disposal once the carrier gets on site? I've had these maddening all night affairs where the vendor says "we're all clean to our next device in Deluth (or wherever). Besides replacing optics, shutting/no shutting the interface, what other tools would help to isolate the cause of these errors? Thank you.

(BTW A tech at the data center tried to throw us a loop but the interface went down from UDLD. If there's a way to make a hard loop to us more informative that would be good to know too)
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amigan_99Network EngineerAsked:
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David Johnson, CD, MVPRetiredCommented:
amigan_99Network EngineerAuthor Commented:
The problem turned out to be a fault in equipment many cities away. So after troubleshooting the optics you can work with the provider to send you loops from the intervening retransmission points in path to the other side of the circuit. Be sure to disable USLD during the troubleshooting so the interface stays up. This will let you see which loops still show incremental errors and which not. In this way the carrier can locate the fault.

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amigan_99Network EngineerAuthor Commented:
•UDLD
amigan_99Network EngineerAuthor Commented:
This was the actual solution that resolved the problem of incremental input and FTC errors
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