Description

On PTX10008 platforms running Junos OS Evolved, GRES is enabled by default and cannot be disabled. 

When you insert a new RE (routing engine) with a different software version from the currently active one on the Primary RE, the newly-inserted RE is kept out of the system. Thereafter, the newly-inserted RE does not respond to any software events and remains in its original software version.

Symptoms

  • There is a need to replace the backup RE in PTX10008.
  • The PTX10008 is running 21.2R1-S1-EVO.
  • The replacing RE has a different software version, which is 20.4R2-S2.10-EVO   

Solution

After the backup RE is replaced, the newly-inserted RE is kept out of the system due to different software versions. The active GRES does not let the backup RE to boot up and sync with primary RE.

There are two ways to resolve this issue:

  1. Manually sync-up the software between REs every time RE is replaced:

user@ptx10008-re0> request system software sync ?
Possible completions:
  all-versions         Sync all sw versions to other RE and reboot if current mismatch
  current              Sync current sw version to other RE and reboot if current mismatch
  rollback             Sync rollback sw version to other RE

user@-ptx10008-re0> request system software sync all-versions   
    

  1. ​Configure 'auto-sw-sync ' knob. When you configure this statement, the primary RE of the system copies over all the images (software and configuration) to the new RE and reboots the new RE so it runs the same software version and configuration as the primary RE. By default, it is disabled.

user@-ptx10008-re0# set system auto-sw-sync enable
user@-ptx10008-re0# commit

Modification History

2023-03-28: updated link to Understanding Graceful Routing Engine Switchover.

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