C.4 Trusted/Untrusted Non-3GPP IP Access with DSMIPv6 to Trusted Non-3GPP IP Access with PMIPv6 Handover in the Non-Roaming Scenario

23.4023GPPArchitecture enhancements for non-3GPP accessesRelease 18TS

This clause shows a call flow for a handover when UE moves from a source trusted/untrusted non-3GPP IP access network to a target trusted non-3GPP access network. PMIPv6 is assumed to be used on S2a and DSMIPv6 is assumed to be used on source trusted/untrusted access network.

Figure C.4-1: S2c over trusted or untrusted Non-3GPP IP access to S2a (PMIPv6) Handover

This procedure supports the non-roaming (Figure 4.2.2.1), home routed roaming (Figure 4.2.3-1) and roaming with Local breakout (Figure 4.2.3-4) case. The PCRF in the HPLMN is informed of the change of access and any change in the policy that results is signalled to the Trusted non-3GPP IP Access. The signalling takes place through the vPCRF in the VPLMN. In the case of roaming with Local Breakout, the PDN GW in the VPLMN exchanges messages with the vPCRF.

The optional interaction steps between the gateways and the PCRF in the above figure only occur if dynamic policy provisioning is deployed. Otherwise policy may be statically configured with the gateways.

In case of connectivity to multiple PDNs, step 8 is repeated for each PDN the UE is connected to. This step can occur in parallel for each PDN. Other impacts related to the handover for multiple PDNs are described in clause 8.1. Alternatively, if supported by non-3GPP access technology and if the UE does not provide any APN upon handover attach in the trusted non-3GPP IP access, Step 5 is repeated for each PDN the UE is connected to, instead of Step 8. DSMIPv6 de-registration in step 9 will be performed for each PDN connection. These steps can occur in parallel for each PDN.

1. The UE is connected to the trusted/untrusted Non-3GPP Access using S2c.

1a. There is an IPsec tunnel between the UE and the ePDG if UE is connected over untrusted access network.

2. The UE moves to a Trusted Non-3GPP Access network.

3. The EAP authentication procedure is initiated and performed involving the UE, Trusted Non-3GPP IP Access and the 3GPP AAA Server. In the roaming case, there may be several AAA proxies involved. As part of the authentication procedure, the information of the selected PDN GW, e.g. PDN GW’s address, is conveyed to the MAG in the Trusted Non-3GPP IP Accesses. The PDNs the UE is connected to are obtained from the HSS with the UE subscriber profile.

4. After successful authentication and authorization, the L3 attach procedure is triggered.

5. The UE continues the attach to the Trusted Non-3GPP IP Access as defined in Steps 5-8 of Figure 8.2.2-1, except that the IP CAN session modification defined in step 7 is triggered as explained below.

6. L3 attach procedure is completed. IP connectivity between the UE and the PDN GW is set for uplink and downlink direction over the trusted non-3GPP IP access.

7. The PMIPv6 tunnel is set up between the Trusted Non-3GPP IP Access and the PDN GW. The UE can send/receive IP packets at this point.

8. In case of connectivity to multiple PDNs, the UE establishes connectivity to all the PDNs besides the Default PDN that the UE was connected to before the handover as described in clause 6.8.1.

9. The UE sends a BU (lifetime) to the PDN GW to de-register its DSMIPv6 binding that was created while the UE was in non-3GPP access system. The PDN GW responds with a BA message.

Any time after step 5, prior to receiving the de-registration Binding Update from the UE, the PDN GW may de-register the DSMIPv6 binding. In this case the PDN GW shall send a Binding Revocation Indication message to the UE.

Following the de-registration of the DSMIPv6 binding due to reception of de-registration Binding update or due to triggering Binding Revocation, the PDN GW triggers PCEF initiated IP CAN session modification, instead of doing it as part of the step 5.

10. The PCRF initiates "PCRF-initiated Gateway Control Session Termination" procedure to release the resources in the non-3GPP access. This procedure is triggered by the PCEF-Initiated IP‑CAN Session Modification Procedure with the PCRF.