[Chassis 202405]: Supervisor ungraceful restart take ~7+ seconds for traffic to converge. Need help with its optimization

[deepak-singhal0408]

Context:
We run snappi based route convergence tests to get the convergence results.
Testplan Doc:
https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/Convergence%20measurement%20in%20data%20center%20networks.md

For supervisor Ungraceful restart TC(test case in below file): We observed 7+ seconds of traffic loss..
https://github.com/sonic-net/sonic-mgmt/blob/master/tests/snappi_tests/multidut/bgp/test_bgp_outbound_ungraceful_restart.py

Please Note: our topology consists of 16 Uplinks.. And we advertise 30k IPv4 + 30k IPv6 prefixes from upstream Neighbors.

Opening this issue to optimize traffic convergence in this production scenario...

Our results:

+----------------------------------------+--------------+------------------+---------------------+---------------+--------------------------------------------+                                                
| Test Name                              |   Iterations | Traffic Type     |   Uplink ECMP Paths |   Route Count |   Avg Calculated Packet Loss Duration (ms) |                                                
|----------------------------------------+--------------+------------------+---------------------+---------------+--------------------------------------------|                                                
| Supervisor Ungraceful Re-start (DOWN)) |            1 | ['IPv4', 'IPv6'] |                  16 |         60000 |                              6654.6        |                                                
| Supervisor Ungraceful Re-start (UP)    |            1 | ['IPv4', 'IPv6'] |                  16 |         60000 |                                 0.00501151 |                                                
+----------------------------------------+--------------+------------------+---------------------+---------------+--------------------------------------------+ 

[deepak-singhal0408]

techsupport from the device uploaded here..
https://microsoft.sharepoint.com/:u:/t/AristaSONiCWorkingGroup/EarGx0hNHKNNrL3O4ZU2gq8BOkuBn04c0CYy0H60aqmCKw?e=bvZPRM