When a UE re-establishes on a different DU, the physCellId in the
re-establishment request (from the old cell) will differ from the
new DU's physCellId. The previous check incorrectly treated this as
a "too fast movement" scenario and triggered fallback to RRC setup.
This fix distinguishes between two scenarios:
1. Different DU scenario: physCellId differs because UE is on a
different DU - this is legitimate and should be allowed. UE
Context Setup will be triggered at RRCReestablishmentComplete.
2. Same DU but different physCellId: "too fast movement" scenario
- fallback to RRC setup as before.
The fix checks if assoc_id != ue_data.du_assoc_id to detect a
different DU scenario and allows re-establishment in that case.
This addresses the issue where re-establishment on a different DU
was incorrectly rejected, preventing proper UE Context Setup per
TS 38.401 Section 8.7.
Guido Casati
825cbcdb47