Why I did it
Support for SONIC chassis isolation using TSA and un-isolation using TSB from supervisor module
Work item tracking
Microsoft ADO (number only): 17826134
How I did it
When TSA is run on the supervisor, it triggers TSA on each of the linecards using the secure rexec infrastructure introduced in sonic-net/sonic-utilities#2701. User password is requested to allow secure login to linecards through ssh, before execution of TSA/TSB on the linecards
TSA of the chassis withdraws routes from all the external BGP neighbors on each linecard, in order to isolate the entire chassis. No route withdrawal is done from the internal BGP sessions between the linecards to prevent transient drops during internal route deletion. With these changes, complete isolation of a single linecard using TSA will not be possible (a separate CLI/script option will be introduced at a later time to achieve this)
Changes also include no-stats option with TSC for quick retrieval of the current system isolation state
This PR also reverts changes in #11403
How to verify it
These changes have a dependency on sonic-net/sonic-utilities#2701 for testing
Run TSA from supervisor module and ensure transition to Maintenance mode on each linecard
Verify that all routes are withdrawn from eBGP neighbors on all linecards
Run TSB from supervisor module and ensure transition to Normal mode on each linecard
Verify that all routes are re-advertised from eBGP neighbors on all linecards
Run TSC no-stats from supervisor and verify that just the system maintenance state is returned from all linecards
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