Description

This article provides one of the possible solutions whenever the switch became unreachable after software upgrade.

Symptoms

The switch was upgraded from version 15.1X53 to version 21.2R1-S2 via SSH, and it became unreachable via SSH and does not respond to ping from remote end.

Solution

If the current configuration has syntax differences with the expected syntax of the new version 21.2R1-S2, chances are that the configuration is not taking effect after the software upgrade was completed. The switch is simply unable to commit incompatible configuration, even though it was already committed prior to the upgrade.

Note that you do not need to always commit after every software upgrade, but it is a good practice to confirm that the configuration is compatible with the new software version.

If the switch suffers from the described issue, the result is that the same will be inaccessible via SSH nor will it respond to ping, because SSH access and any ping response depends on the IP addresses and the SSH service configured on the switch, and if the configuration is not taking effect due to the mentioned conflicts, none of the configured features will work.

To figure this out, connect console to the switch, and go to configure mode, then issue a "commit check", and if you see the below commit errors or any other similar concern, proceed to make the necessary corrections:

Scenario 
{master:0}[edit]
user@switch# commit check
[edit system archival]
  'configuration'
    Missing mandatory statement: 'archive-sites'
[edit vlans VLAN-NAME l3-interface]
  'l3-interface irb.12'
    Interface must already be defined under [edit interfaces]
[edit vlans VLAN-NAME2 l3-interface]
  'l3-interface irb.11'
    Interface must already be defined under [edit interfaces]
error: configuration check-out failed: (statements constraint check failed)

Solution 
{master:0}[edit]
user@switch# system archival configuration archive-sites "[email protected]/var/tmp/"

{master:0}[edit]
user@switch# set interfaces irb.11 family inet address 192.168.0.2/24

{master:0}[edit]
user@switch# set interfaces irb.12 family inet address 192.168.0.3/24

{master:0}[edit]
user@switch# commit check
configuration check succeeds

After confirming that the configuration is committable, you may proceed to commit normally and the switch should be working as expected.

Modification History

2024-08-13 : Article Created