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Input/CRC errors in 10gb downlink interface

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TitleInput/CRC errors in 10gb downlink interface
Symptoms
mlx# show stat eth 2/6

PORT 2/6 Counters:
         InOctets       307345621835           OutOctets       810718330921
           InPkts          993107072             OutPkts         1188474634
  InBroadcastPkts            5231846    OutBroadcastPkts            5051681
  InMulticastPkts            9838304    OutMulticastPkts           14233207
    InUnicastPkts          978036296      OutUnicastPkts         1169189746
       InDiscards                  0         OutDiscards                  0
         InErrors                626           OutErrors                  0
     InCollisions                  0       OutCollisions                  0
                                       OutLateCollisions                  0
        Alignment                  0                 FCS                626
   InFlowCtrlPkts                  0     OutFlowCtrlPkts                  0
        GiantPkts                  0           ShortPkts                  0
     InBitsPerSec            2777841       OutBitsPerSec           10041738
     InPktsPerSec               1472       OutPktsPerSec               2182
    InUtilization              0.03%      OutUtilization              0.10%

 
Environment
  • NetIron
  • MLX/XMR
  • MLXe
  • CER/CES
Cause
Most likely it is Layer 1 issue. Worst case scenario it will be port issue.
Resolution
If there are CRC and input errors on a particular port, follow the below procedure:

Possible SFP issue:
  1. Change the SFP on one side and check if the errors stop.
  2. If errors are still present, change the SFP on the other end and check for errors.
  3. If above steps don't help check for cable/fiber issue.
Possible fiber/cable issue:
  1. If the errors are still present and the port is a fiber port, then clean the fiber end on both sides.
  2. If the CRC and input errors are still present then use optic cleaning swabs or spray air to clean the optic and reconnect the fiber.
  3. Connect a new fiber strand and see the errors still stays or not.
  4. Move the fiber/cable to a different port and see if the errors follow. If they do, then it is cable/fiber strand issue.
  5. If the above steps don't resolve the issue check for possible patch panel port issue. If the customer doesn't use patch panel then check for port issues.

Possible patch-panel port issue:

  1.  If the customer has a patch panel between the two devices, then check the optics on the patch-panel ports. Change the optics to see it resolves the issue.
  2. If the issue is not resolvesed, check the cable connected on the patch-panel ports. Change it to see it stops the errors seen on the ports.
  3. If the errors are still seen then change the patch-panel ports to a known good port to rule out port issue on the patch-panel.
  4. If the input errors are still seen after changing the patch panel port then check for possible port issue on both end.
Possible port issue:
  1. Move the cable and SFP to a known good port (with no errors) on one end and check if you still see the errors. If you don't then it could be a port issue.
  2. If the errors still persists after the above step then move the cable and SFP on the other end to a known good port and check for errors on the interface. If you don't see them then it could be a port issue.
Additional notes

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