Successful handover does not require complete ue ctx release

src/amf-app/amf_n2.cpp

@@ -1309,6 +1309,28 @@ void amf_n2::handle_itti_message(itti_ue_context_release_complete& itti_msg) {
     return;
   }
 
+  std::shared_ptr<ue_ngap_context> unc = {};
+
+  if (!amf_ue_id_2_ue_ngap_context(amf_ue_ngap_id, unc)) {
+    Logger::amf_app().error(
+        "No UE NGAP context for amf_ngap_id %s, exit", amf_ue_ngap_id);
+    return;
+  }
+
+  //verify release cause -> if HandoverSuccessful no further operations required
+  if(unc->release_cause == Ngap_CauseRadioNetwork_successful_handover){
+    std::shared_ptr<gnb_context> gc = {};
+    if (!assoc_id_2_gnb_context(itti_msg.assoc_id, gc)) {
+      Logger::amf_n2().error(
+          "gNB with assoc_id (%d) is illegal", itti_msg.assoc_id);
+      return;
+    }
+    remove_ran_ue_ngap_id_2_ngap_context(ran_ue_ngap_id, gc->gnb_id);
+    unc->release_cause = 0;
+    return;
+  }
+
+
   // Change UE status from CM-CONNECTED to CM-IDLE
   std::shared_ptr<nas_context> nc = {};
   if (!amf_n1_inst->amf_ue_id_2_nas_context(amf_ue_ngap_id, nc)) {
@@ -2031,10 +2053,13 @@ void amf_n2::handle_itti_message(itti_handover_notify& itti_msg) {
     return;
   }
 
+  unc->release_cause         = Ngap_CauseRadioNetwork_successful_handover;
+  unc->last_ran_ue_ngap_id   = unc->ran_ue_ngap_id;
   unc->ran_ue_ngap_id        = ran_ue_ngap_id;  // store new RAN ID
   unc->target_ran_ue_ngap_id = 0;               // Clear target RAN ID
   unc->ng_ue_state           = NGAP_UE_CONNECTED;
   unc->gnb_assoc_id          = itti_msg.assoc_id;  // update serving gNB
+
   set_ran_ue_ngap_id_2_ue_ngap_context(ran_ue_ngap_id, gc->gnb_id, unc);
 }
 

src/contexts/ue_ngap_context.hpp

@@ -44,10 +44,12 @@ class ue_ngap_context {
     ran_ue_ngap_id        = 0;
     amf_ue_ngap_id        = 0;
     target_ran_ue_ngap_id = 0;
+    last_ran_ue_ngap_id   = 0;
 
     sctp_stream_recv = {};
     sctp_stream_send = {};
 
+    release_cause       = {};
     gnb_assoc_id        = {};
     target_gnb_assoc_id = {};
     ueContextRequest    = false;
@@ -67,6 +69,7 @@ class ue_ngap_context {
     initialUEMsg.size = 0;
   }
 
+  uint32_t last_ran_ue_ngap_id;
   uint32_t ran_ue_ngap_id;         // 32bits
   long amf_ue_ngap_id : 40;        // 40bits
   uint32_t target_ran_ue_ngap_id;  // 32bits, for HO
@@ -91,6 +94,9 @@ class ue_ngap_context {
   uint8_t ncc;  // Next Hop Chaining Counter
 
   OCTET_STRING_t initialUEMsg;
+
+  //store the cause of Release Command
+  Ngap_CauseRadioNetwork_t release_cause;
 };
 
 #endif