Every commit operation, regardless of the configuration changes, triggers an ISIS re-calculation and updates the LSP (Link State PDU). This occurs even when the committed changes are unrelated to ISIS.

• ISIS SPF (Shortest Path First) calculation is performed after each commit.

• LSP is updated following every commit operation.

• The timestamps of commit operations closely align with ISIS SPF log entries marked as "Reconfig" or "Updated LSP".

Example: 

Commit timestamps:

Mar 8 09:38:31.004 2024 mgd[PID]: %INTERACT-4-UI_COMMIT_COMPLETED: : commit complete
Mar 8 09:40:52.171 2024 mgd[PID]: %INTERACT-4-UI_COMMIT_COMPLETED: : commit complete

Corresponding ISIS SPF log entries:

Fri Mar 8 09:38:31 0.014612 2 Reconfig
Fri Mar 8 09:38:31 0.013713 29 Updated LSP DCRE-DEOFF-01-0001.00-00
Fri Mar 8 09:40:52 0.014264 2 Reconfig
Fri Mar 8 09:40:52 0.013711 29 MPLS Shortcut LSP change
Fri Mar 8 09:40:52 0.011553 1 Updated LSP DCRE-DEOFF-01-0001.00-00 

Cause:

This issue is observed when global SRGB (Segment Routing Global Block) is configured. With every commit, the global SRGB is not reset, resulting in LSP regeneration.

Affected Platforms:
All Junos and Junos Evolved platforms

Conditions:
ISIS is configured on the device
Global SRGB is configured

Impact:
There is no functional impact due to this issue. The SPF automatically converges after each recalculation

• Under the ISIS protocol configuration, replace the global SRGB with a local SRGB configuration.

Resolution:

This issue has been resolved in the following software versions:

Junos Evolved:
21.4R3-S6-EVO, 22.1R3-S5-EVO, 22.2R3-S3-EVO, 22.3R3-S2-EVO, 22.4R3-S1-EVO, 23.2R2-EVO, 23.4R1-S1-EVO, 23.4R2-EVO, 24.1R1-EVO

Junos:
21.2R3-S7, 21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, 22.4R3-S1, 23.2R2, 23.4R1-S1, 23.4R2, 24.1R1

Additional Information:
For more details, refer to PR1778841 - https://prsearch.juniper.net/PR1778841