Section: 4.23.7.3.4 Handover Cancel
Content: Figure 4.23.7.3.4-1: Handover Cancel procedure 1. Step 1~3 in clause 4.11.1.2.3 are performed. Case: I-SMF Change, step 4~9 are skipped for I-SMF Insertion case and I-SMF Removal case. 4. T-AMF to Target I-SMF: Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication). The target AMF invokes Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication) to the target I-SMF to release the SM Context and all resources allocated on the target I-SMF during preparation phase. 5a. Target I-SMF to Target I-UPF: N4 Session Release Request. The target I-SMF invokes N4 Session Release Request to target I-UPF, to release all resources allocated for the N4 session. 5b. Target I-UPF to Target I-SMF: N4 Session Release Response. 6. [Conditional] Target I-SMF to Source I-SMF: Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication). If indirect forwarding tunnel is setup during preparation phase, the target I-SMF initiates Nsmf_PDUSession_UpdateSMContext Request to the source I-SMF, indicating the source I-SMF to delete the resources temporarily allocated for indirect forwarding tunnel. 7a. [Conditional] Source I-SMF to Source I-UPF: N4 Session Modification Request. The source I-SMF invokes N4 Session Modification Request to source I-UPF, to delete all resources allocated for indirect forwarding tunnel. 7b. [Conditional] Source I-UPF to Source I-SMF: N4 Session Modification Response. 8. [Conditional] Source I-SMF to Target I-SMF: Nsmf_PDUSession_UpdateSMContext Response. 9. Target I-SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response. Case: I-SMF Insertion, step 10~18 are skipped for I-SMF Change case and I-SMF Removal case. 10. T-AMF to Target I-SMF: Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication). The target AMF invokes Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication) to the target I-SMF to release the SM Context and all resources allocated on the target I-SMF during preparation phase. 11a. Target I-SMF to Target I-UPF: N4 Session Release Request. The target I-SMF invokes N4 Session Release Request to target I-UPF, to release all resources allocated for the N4 session. 11b. Target I-UPF to Target I-SMF: N4 Session Release Response. 12. Target I-SMF to SMF: Nsmf_PDUSession_Update Request (PDU Session ID, Relocation Cancel Indication). The target I-SMF invokes Nsmf_PDUSession_Update Request (PDU Session ID, Relocation Cancel Indication) to the SMF, to release the PDU Session resources allocated during preparation phase, e.g. CN Tunnel for N9. 13a. [Conditional] SMF to UPF (PSA): N4 Session Modification Request. If CN Tunnel for N9 is allocated during preparation phase, i.e. the CN Tunnel for N3 and N9 are different, the SMF asks UPF (PSA) to release the CN Tunnel on N9. 13b. [Conditional] UPF(PSA) to SMF: N4 Session Modification Response. 14. SMF to Target I-SMF: Nsmf_PDUSession_Update Response. 15. [Conditional] Target I-SMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (Operation Type). If indirect forwarding tunnel is setup during preparation phase, the target I-SMF initiates Nsmf_PDUSession_UpdateSMContext Request (Operation Type) to the SMF, indicating the SMF to delete the resources temporarily allocated for indirect forwarding tunnel. 16a. [Conditional] SMF to UPF (PSA): N4 Session Modification Request. The SMF invokes N4 Session Modification Request to UPF (PSA), to delete all resources allocated for indirect forwarding tunnel. 16b. [Conditional] UPF (PSA) to SMF: N4 Session Modification Response. 17. [Conditional] SMF to Target I-SMF: Nsmf_PDUSession_UpdateSMContext Response. 18. Target I-SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response. Case: I-SMF Removal, step 19~24 are skipped for I-SMF Insertion case and I-SMF Change case. 19. T-AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication). The target AMF invokes Nsmf_PDUSession_UpdateSMContext Request (Relocation Cancel Indication) to the SMF to release the SM Context and all resources allocated on the SMF during preparation phase. 20a. [Conditional] SMF to UPF (PSA): N4 Session Modification Request. If CN Tunnel for N3 is allocated during preparation phase, i.e. the CN Tunnel for N3 and N9 are different, the SMF asks UPF (PSA) to release the CN Tunnel on N3. 20b. [Conditional] UPF (PSA) to SMF: N4 Session Modification Response. 21. [Conditional] SMF to Source I-SMF: Nsmf_PDUSession_UpdateSMContext Request (Operation Type). If indirect forwarding tunnel is setup during preparation phase, the SMF initiates Nsmf_PDUSession_UpdateSMContext Request (Operation Type) to the source I-SMF, indicating the source I-SMF to delete the resources temporarily allocated for indirect forwarding tunnel. 22a. [Conditional] Source I-SMF to Source I-UPF: N4 Session Modification Request. The source I-SMF invokes N4 Session Modification Request to source I-UPF, to delete all resources allocated for indirect forwarding tunnel. 22. [Conditional] Source I-UPF to SMF: N4 Session Modification Response. 23. [Conditional] Source I-SMF to SMF: Nsmf_PDUSession_UpdateSMContext Response. 24. SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response.