5.3 Detach for PMIP-based S5/S8

23.4023GPPArchitecture enhancements for non-3GPP accessesRelease 18TS

The procedure in this clause provides the PMIPv6-based S5/S8 variants to all E-UTRAN Detach Procedures, including UE, MME or HSS initiated detach procedure (TS 23.401 [4] clause 5.3.8).

In case of detach, all the bearers at the Serving GW are terminated. Further, the IP CAN session for the UE in the PDN GW is also terminated.

If the UE is connected to both E-UTRAN and a non-3GPP access before the UE triggers detach on E-UTRAN, and the UE wants to preserve all or a subset of the active PDN connections routed over E-UTRAN system, a UE initiated PDN disconnection procedure shall be performed for each of the PDN connections that are not required to be preserved. The UE then shall initiate the applicable handover procedure to transfer to the access system through which the UE remains attached to the Evolved Packet Core each of the PDN connections to be preserved.

Figure 5.3-1: E-UTRAN Detach Procedure for PMIP-based S5/S8

NOTE: When multiple PDN connections are active a part of this procedure including steps A.1 to A.4 are repeated for each PDN connection of the UE.

The optional interaction steps between the gateways and the PCRF in Figure 5.3-1 only occur if dynamic policy provisioning is deployed. Otherwise policy may be statically configured with the gateway.

This procedure applies to the Non-Roaming (Figure 4.2.1-1), Roaming (Figure 4.2.1-2) and Local Breakout (Figure 4.2.3-4) cases. For the Roaming and Local Breakout cases, the vPCRF forwards messages between the Serving GW and the hPCRF. In the Local Breakout case, the vPCRF forwards messages between the PDN GW and the hPCRF.

In the non-roaming case, the vPCRF is not involved at all.

A.1) The Serving GW initiates the Gateway Control Session Termination Procedure with the PCRF as specified in TS 23.203 [19]. The S‑GW provides information to enable the PCRF to unambiguously identify the IP‑CAN session corresponding to the Gateway Control Session and indicates User Location Information and/or UE Time Zone Information to the PCRF as an Event Report if the corresponding event trigger is set. This results in the removal of the Gateway Control session in S‑GW.

A.2) The Serving GW sends a Proxy Binding Update (MN NAI, APN, lifetime=0) message to the PDN GW to release the PDN connection of the UE at the PDN-GW. If only one PDN connection per APN is supported then the MN NAI and the APN identify the PDN connection of the UE. If multiple PDN connections per APN are supported then the MN NAI, the APN and the EPS bearer identity of the default bearer identify the PDN connection of the UE. The lifetime field indicates that the message is used to release the PDN connection of the UE at the PDN-GW.

A.3) The PDN GW initiates the PCEF-Initiated IP‑CAN Session Termination Procedure with the PCRF as specified in TS 23.203 [19]. The PDN GW provides information to enable the PCRF to uniquely identify the IP‑CAN session. This results in the removal of IP-CAN session related information in the PCRF and in the PDN GW.

A.4) The PDN GW responds to the Serving GW with the result of the PDN connection release with Proxy Binding Update Acknowledgement