The AMF interacts and supports multiple nodes. A few of the nodes are as the following:

• UE/GNB

• UDM

• AUSF

• SMF

When multiple nodes send simultaneous request towards the AMF, there's a possibility of collision at the AMF node.

The AMF collision handling feature supports handling the collision between different procedures at the AMF node.

Previous Behavior: The previous behavior activities listed as follows:

• The timer value can be configured in any range between <unsignedInt, 0–35712000>.

• The guard timer gets started on receiving the N14 context transfer update request.

• In the guard timer running state, no handling of UDM Deregistration notification is present.

New Behavior: The new behavior activities listed as follows:

• The CLI is updated to configure guard timer values in the range [0-10].

  The default value is 5. The value 0 is used to disable the timer in the procedure.

• If enabled, the UE context guard timer starts on receiving the context transfer request.

• On a successful transfer, the UE context will be cleaned on timer expiry.

Customer Impact: No impact.

Previous Behavior: When the UE is requested, but the DNN doesn’t match the case of a configured DNN (AMF) or a subscribed DNN (from the UDM).

New Behavior: The UE requested DNN, is now compared case-insensitive with both the local configuration, and the UDM subscription data. This case-insensitive comparison is as per the standard specification.

Customer Impact: No impact.

Previous Behavior: When the HO failure is received from the gNB, the AMF was sending smfupdateCtxtReq to the SMF with n2smInfoType field present, even when n2smInfo wasn’t received from the AN.

New Behavior: When the AMF receives the HO failure note from the gNB, it acts as follows:

• The AMF sends the SMF Update Context Request to the SMF:

  • Without the n2smInfoType field if n2smInfo isn't received from the AN.

  • It includes the HoState and cause attribute.

Customer Impact: No impact.

Previous Behavior: The previous behavior activities listed as follows:

• The UE sends a Service Request in Uplink NAS transport for data or signaling.

• The AMF sends a Service Reject since the UE is in the NOT ALLOWED AREA.

• The AMF sends the UE context release command to the gNB post reject and the gNB replies with the UE context release complete. The UE isn’t marked as idle after this step.

The UE context release command was sent when the AMF initiated a service reject action for the UE in connected mode.

New Behavior: The new behavior activities listed as follows:

• The UE continues sending a Service Request in Uplink NAS transport for data or signaling.

• The AMF continues sending a Service Reject since the UE is in the NOT ALLOWED AREA.

• The AMF doesn't send the UE context release command to the gNB post reject and the UE is still in a connected state.

• The UE context release command doesn't get initiated from the AMF when the service reject gets initiated in connected mode.

• The UE sends a Service Request to the AMF in the Uplink NAS Transport NGAP message and the PDU reactivation gets initiated properly.

Customer Impact: No impact.