Description

This article explains the different fabric states that can be encountered on MX platforms. 

Solution

The MX software maintains states at two levels of the fabric components; planes and links.

A fabric plane can be in any one of the following states: 

  • Online: A fabric plane with all of its links are error free and enabled, ready for carrying data traffic.
  • Spare: A fabric plane with all of its links are error free, in a standby mode, ready to be enabled
  • Offline: A fabric plane with all of its links in an un-trained state. This state can be a result of user requested operation, or can be triggered by fatal error(s) detected by the system.
  • Check: A fabric plane with one or more of its link(s) or destination(s) has errors.
  • Empty: A fabric plane whose hardware does not exist in the chassis.

A fabric link can be in any one of the following states:

  • Unused: A fabric is in an un-trained, un-used mode.
  • OK: A fabric is trained, error-free, ready to be enabled.
  • Enabled: A fabric link is error free and currently enabled.
  • Disabled: A fabric link is disabled. This can be a result of user operation, or done by the system due to link error.
  • Error: Fabric error(s) has been detected on the link, or the link training has failed.
  • Enable Error: Error happened during the link enable/disable operation.
  • Dest Error: Destination error is detected on this link, but can be caused by remote side links.


Following command provides related information :

root@rtr> show chassis fabric legend    
 
Legend for show chassis fabric state:
 
 Unused:
     The link is not trained and is disabled.
 Links ok:
     The link is in error-free condition and carries traffic only if it belongs to an online plane.
 Link error:
     The link encounters CRC errors and carries traffic only if it belongs to an online plane.
 Link error: (TF)
     The link encounters training error and is disabled.
 Destination error:
     The FPC has reported destination errors on the link and the link is disabled.
 Plane disabled:
     The link is disabled due to error or plane is offlined.
 Plane enabled:
     The link is enabled and carries traffic.
 Plane enable error:
     The link encounters ASIC error and is disabled.
 
 Note 1: (TF)
     When present, indicates training failure.
 
 Note 2: Plane link state
     Plane link state (show chassis fabric plane) only tracks whether a link is trained or not, therefore possible plane link states are: Unused, Links ok, Link error (for CRC or TF).
 
 Note 3: Plane Online/Spare state
     A link may carry traffic only if it is from an online plane.
     Refer to show chassis fabric summary [extended] for Online/Spare plane state.

root@rtr> show chassis fabric summary extended   <-- "extended" option is available from Junos release 14.1R2
Plane   State      Link   Link  Destination errors  Uptime
                   Error  TF    Local / Remote 
 0      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 34 seconds
 1      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 34 seconds
 2      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 34 seconds
 3      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 33 seconds
 4      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 33 seconds
 5      Online     NO     NO        NO/  NO         1 day, 14 hours, 45 minutes, 33 seconds
 

Additional commands useful for fabric troubleshooting:

show chassis fabric destinations
show chassis fabric fpcs 
show chassis fabric map
show chassis fabric plane
show chassis fabric reachability 
show chassis fabric redundancy-mode
 

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