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RRC: Improve UE context lookup for re-establishment on different DU

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Add intermediate fallback to rrc_gNB_get_ue_context_by_rnti_any_du() in
re-establishment request handling to better handle cases where UE
re-establishes on a different DU.

RNTI is NOT globally unique - different DUs can assign the same RNTI to
different UEs. The assoc_id check in rrc_gNB_get_ue_context_by_rnti()
disambiguates RNTI across DUs and prevents returning the wrong UE.

However, during re-establishment on a different DU, du_assoc_id hasn't
been updated yet (message comes from new DU, but ue_data.du_assoc_id
still points to old DU), causing the primary lookup to fail even though
the UE exists.

The lookup now uses a three-tier fallback:
1. Primary: rrc_gNB_get_ue_context_by_rnti() with assoc_id check
   (normal case: same DU)
2. Fallback 1: rrc_gNB_get_ue_context_by_rnti_any_du() by RNTI only
   (re-establishment on different DU)
3. Fallback 2: rrc_gNB_get_ue_context_source_cell() using physCellId
   (handover scenarios)
This commit is contained in:
Guido Casati
2026-01-29 10:17:42 +01:00
parent d18c2d27f2
commit 9a11690f81
1 changed files with 9 additions and 3 deletions
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openair2/RRC/NR/rrc_gNB.c
+9 -3
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@@ -1510,12 +1510,18 @@ static void rrc_handle_RRCReestablishmentRequest(gNB_RRC_INST *rrc,
goto fallback_rrc_setup; goto fallback_rrc_setup;
} }
// Try to find UE context by RNTI and assoc_id (normal case: same DU)
ue_context_p = rrc_gNB_get_ue_context_by_rnti(rrc, assoc_id, old_rnti); ue_context_p = rrc_gNB_get_ue_context_by_rnti(rrc, assoc_id, old_rnti);
if (ue_context_p == NULL) { if (ue_context_p == NULL) {
ue_context_p = rrc_gNB_get_ue_context_source_cell(rrc, physCellId, old_rnti); // Fallback 1: Try to find UE by RNTI only (re-establishment on different DU scenario)
ue_context_p = rrc_gNB_get_ue_context_by_rnti_any_du(rrc, old_rnti);
if (ue_context_p == NULL) { if (ue_context_p == NULL) {
LOG_E(NR_RRC, "NR_RRCReestablishmentRequest without UE context, fallback to RRC setup\n"); // Fallback 2: Try to find UE by source cell (handover scenario)
goto fallback_rrc_setup; ue_context_p = rrc_gNB_get_ue_context_source_cell(rrc, physCellId, old_rnti);
if (ue_context_p == NULL) {
LOG_E(NR_RRC, "NR_RRCReestablishmentRequest without UE context, fallback to RRC setup\n");
goto fallback_rrc_setup;
}
} }
} }
gNB_RRC_UE_t *UE = &ue_context_p->ue_context; gNB_RRC_UE_t *UE = &ue_context_p->ue_context;