Ultra Cloud Core 5G Access and Mobility Management Function, Release 2023.01 - Configuration and Administration Guide - Idle Entry Procedure [Cisco Ultra Cloud Core - Access and Mobility Management Function]

Feature Summary and Revision History

Table 1. Summary Data
Applicable Product(s) or Functional Area	AMF
Applicable Platform(s)	SMI
Feature Default Setting	Enabled - Always-on
Related Documentation	Not Applicable

Table 2. Revision History
Revision Details	Release
First introduced.	2020.01

The AMF supports transitioning the UE from ECM_CONNECTED to ECM_IDLE state.

This section describes how this feature works.

This section describes the key call flow for this feature.

This section describes the gNB-Initiated UE Context Release Procedure call flow.

Table 3. gNB-Initiated UE Context Release Procedure Call Flow Description
Step	Description
1	The AMF receives the UE Context Release Request from the gNB.
2	The AMF sends the UE Context Release Command to the gNB.
3	The AMF receives the UE Context Release Complete from the gNB.
4	The SmContextUpdate procedure is started for all the existing PDU sessions of the subscriber.
5	Once the SmContextUpdate is complete, the UE is moved to the IDLE state.
6	The NGAP EP sends the Context Release Complete to the AMF Service. The T3512 timer is started when processing this message.
7	On expiry of the T3512 timer, the UE Detach Timer is started.
8	On expiry of the UE Detach Timer, the deregistration procedure is triggered.
9	The SMF sends the 204 message to the REST EP.
10	The REST EP sends the PSM Context Update Response message to the AMF Service.

This section describes the UE or NW-Initiated Deregistration followed by UE Release Procedure call flow.

Table 4. UE or NW-Initiated Deregistration followed by UE Release Procedure Call Flow Description
Step	Description
1	The UE or NW-Initiated Deregistration procedure is completed. The Deregistration Request or Accept is completed and the UE is moved to the deregistered state.
2	The AMF sends the UE Context Release Command to the gNB.
3	The AMF receives the UE Context Release Complete from the gNB.
4	As the UE deregistration is already complete and the UE is moved to the deregistered state, the UE Context or subscriber Cleanup is triggered, and the subscriber and session is deleted from CDL.