When the UE has attached to the non-3GPP access network, the UE may send a MIPv4 Agent Solicitation as specified in RFC 5944
Upon first receiving a MIPv4 Agent Advertisement message from a FA or detecting a reboot of the FA through inspection of the Agent Advertisement message sequence number, the UE shall select one care-of address included in the Mobility Agent Advertisement Extension and shall send an RRQ to the FA as specified in RFC 5944
with the care-of address included in the Care-of Address field of the RRQ message. The UE shall set the source address and Home Address field to the unspecified address (i.e. 0.0.0.0). The UE shall clear bits S (simultaneous binding) and D (decapsulation by mobile node), and set bit T (reverse tunnelling) to request reverse tunnelling. The UE shall also include the NAI extension as specified in RFC 2794
As part of MIPv4 security, the UE shall include the Mobile-Home Authentication extension within the RRQ as specified in RFC 5944
. The UE shall set the authenticator and SPI fields of the of the Mobile-Home authentication extension to the MN-HA key and associated MN-HA-SPI generated as described in TS 33.402
. If the non-3GPP access specific procedures require a security association between the UE and FA, the UE shall also include the Mobile-Foreign Authentication extension within the RRQ as specified in RFC 5944
. The UE shall set the authenticator and SPI fields of the of the Mobile-Foreign authentication extension to the MN-FA key and associated MN-FA-SPI generated as described in TS 33.402
If the UE already knows the IP address of the HA (e.g. when the HA address is pre-configured) the UE shall include that IP address in the Home Agent field.
If the UE does not know the IP address of the HA, the UE shall include the unspecified address (i.e. 0.0.0.0) in the Home Agent field.
If the UE has established a mobility binding with a given PDN and connection to an additional PDN is desired, the UE shall include the APN of the desired PDN within a Service Selection extension as defined in RFC 5446
within an RRQ as described in RFC 5944
If the UE is registered on a trusted non-3GPP access network and maintenance of its registered mobility binding is desired, the UE shall re-register before the expiration of the lifetime of the registration as specified in RFC 5944
. If the UE has established connectivity to multiple PDNs, the UE shall re-register all mobility bindings.
When the UE receives a Registration Reply (RRP) from the FA, the UE shall perform the validity checks and process the message as specified in RFC 5944
to include validation of the Mobile-Home Authentication extension and, if present, the Mobile-Foreign Authentication extension. After receiving a successful RRP, the UE shall store the HA address and the home address and may send data using the home address.