Section: 4.2.7.2.3 Re-Creating NGAP UE-TNLA-bindings subsequent to NGAP UE-TNLA-binding release
Content: If the AMF has released the NGAP UE-TNLA-binding in the 5G-AN node for a UE and the 5G-AN node needs to send an N2 message for this UE, the following applies: - The 5G-AN node checks the GUAMI stored in the UE context and the associated AMF: - If the GUAMI is available, 5G-AN selects the AMF which owns that GUAMI. - If GUAMI has been marked as unavailable (i.e. based on AMF unavailable status indication received from AMF) but one corresponding target AMF has been indicated, 5G-AN selects that target AMF even if the GUAMI has not been updated as available by the target AMF. - If GUAMI has been marked as unavailable (i.e. based on AMF unavailable status indication received from AMF) and no corresponding target AMF has been indicated, the 5G-AN selects an AMF from the AMF Set based on AMF Set ID of the GUAMI, as defined in clause 6.3.5 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]. - The 5G-AN node creates an NGAP UE-TNLA-binding for the UE by selecting a TNL association from the available TNL associations permitted for the initial N2 message with the selected AMF, as defined in clause 5.21.1.3 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2],and sends the N2 message to the AMF via the selected TNL association. - The AMF may decide to use the TNL association selected by the 5G-AN or the AMF may modify the NGAP UE-TNLA-binding by triangular redirection. If the NGAP UE-TNLA-binding has been released for a UE and the AMF needs to send an N2 message for this UE, the following applies: - The AMF selects a TNL association from the available TNL associations for the target 5G-AN node and sends the N2 message via this TNL association. The target 5G-AN node creates an NGAP UE-TNLA-binding for the UE based on the TNL association selected by the AMF. The TNL association chosen by the AMF always takes precedence. NOTE: This addresses situations where 5G-AN node and AMF select a TNL association for a UE concurrently.