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CRC errors are seen on Summit X460 stack links and mixed Summit X440 - X460 stack links

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TitleCRC errors are seen on Summit X460 stack links and mixed Summit X440 - X460 stack links
Symptoms
Rx CRC errors are being seen on native stack ports.  These CRC errors can also cause Summit X460 stacks to reboot, communication issues through a stack, and Stack's to reboot with dual master.

Slot-1 Stack.9 # sh port stack-ports rxerrors
 
Port Rx Error Monitor                                  Mon Aug 18 10:17:49 2014
Port      Link     Rx      Rx      Rx        Rx      Rx         Rx         Rx   
          State    Crc    Over    Under     Frag    Jabber      Align      Lost
================================================================================
1:1       A       87       0        0        0        0          0          0
1:2       A        2       0        0        0        0          0          0
2:1       A        1       0        0        0        0          0          0
2:2       A       87       0        0        0        0          0          0
================================================================================
Environment
  • Summit X460 Stack
  • Mixed stacks with Summit X440 and X460 switches
  • Native stacking cables (10 Gig)
Cause
In rare situations Summit X460 native stacking port drive levels can cause CRC errors.  Some of the effects of CRC errors are below.
 
  • Summit X460 stacks reboot
  • Communication issues through a stack
  • Stack reboot with dual master
Resolution
Check stacking cables for good connections, firmly connected with the screws tightened.
If the CRC errors continue, try below steps.

Step 1: Upgrade to the below versions of code or higher
  • EXOS 16.1.0.12
  • EXOS 15.7.0.21
  • EXOS 15.6.2.6
  • EXOS 15.4.2.8-patch1-5
  • EXOS 15.3.4.6-patch1-10
  • EXOS 15.5.3.4-patch1-2
If this does not solve the CRC errors:

Step 2: Change the pre-emphasis value to 7 and port driver to 9

debug hal configure stack-ports pre-emphasis 7 driver-current 9
This is is a switch wide configuration so all stacking links will use this new value.
Note: this is a hidden command, and cannot be tabbed out.  Saving the configuration makes this setting
persistent across reboots.

If this does not solve the CRC errors contact GTAC for further assistance.
Additional notes
To switch back to the default values of the stacking links use this command:
debug hal configure stack-ports pre-emphasis auto

To view the configured pre-emphasis values use the command:

debug hal show stack-ports pre-emphasis

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