8.3b Handover from Trusted Non-3GPP IP Access with MIPv4 FACoA on S2a to 3GPP access

23.4023GPPArchitecture enhancements for non-3GPP accessesRelease 18TS

In this scenario, the session starts in a trusted non-3GPP access system using MIPv4 FA CoA and subsequently, the session hands over to a 3GPP access system. The steps involved are shown in the figure below.

Figure 8.3b-1: Handover from Trusted Non-3GPP IP Access with MIPv4 FACoA on S2a to 3GPP Access

For connectivity to multiple PDNs the following applies:

– If UE is connected to both 3GPP access and non-3GPP access before the handover of PDN connections to 3GPP access is triggered, steps 2 to 16 of Figure 8.2.1.1-1 shall be skipped and the UE shall only perform step 17 of Figure 8.2.1.1-1 for each PDN connection that is being transferred from non-3GPP access.

– If UE is connected only to non-3GPP access before the handover of PDN connections to 3GPP access is triggered, steps 2 to 16 of Figure 8.2.1.1-1 shall be performed. In step 3 of Figure 8.2.1.1-1 the UE shall provide the APN corresponding to one of the PDN connections that are being transferred from non-3GPP access. The UE shall then repeat step 17 of Figure 8.2.1.1-1 for each of the remaining PDN connections that are being transferred from non-3GPP access.

– Steps 4 and 5 of Figure 8.3b-1 shall be repeated for each PDN connection that is being transferred from non-3GPP access.

Other impacts related to the handover for multiple PDNs are described in clause 8.1.

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

1) The UE uses a trusted non-3GPP access system. It has a MIPv4 session with the PDN GW with a FA in the trusted non-3GPP access using FACoA.

2) The UE discovers and attaches to the 3GPP access as defined in Step (C) of Figure 8.2.1.1-1, except that the IP CAN session modification and the path switch are triggered as explained below.

3) The UE may send an Agent Solicitation RFC 5944 [12] message. The HA functionality in the PDN GW sends an Agent Advertisement (AA) RFC 5944 [12] message to the UE.

4) The UE determines that it is back home through inspection of the H bit and advertised prefix within the agent advertisement (AA) received in the previous step. The UE sends a Registration Request message with the destination address set to the HA’s address and with a Lifetime field set to 0 to indicate deregistration. Once the deregistration request is accepted, the UE receives an Registration Response message from the HA.

5) The PDN GW shall initiate resource allocation deactivation procedure in the trusted/untrusted non-3GPP IP access as defined in clause 6.12.