The description of the reference points specific for the non-3GPP access:
N2, N3, N4, N6:
Reference point between the UE and the untrusted non-3GPP access (e.g. WLAN). This depends on the non-3GPP access technology and is outside the scope of 3GPP.
Reference point between the untrusted non-3GPP access and the N3IWF for the transport of NWu traffic.
Reference point between the 5G-RG and the W-AGF which transports the user plane traffic and the N1 NAS protocol. The definition of this interface is outside the scope of 3GPP.
Reference point between the FN-RG and the W-AGF. The definition of this interface is outside the scope of 3GPP.
Reference point between the N5CW devices and the TWAP. It is defined in clause 184.108.40.206
Reference point between the UE and N3IWF for establishing secure tunnel(s) between the UE and N3IWF so that control-plane and user-plane exchanged between the UE and the 5G Core Network is transferred securely over untrusted non-3GPP access.
Reference point between the UE and the TNGF. A secure NWt connection is established over this reference point, as specified in TS 23.502, clause 4.12a.2.2
. NAS messages between the UE and the AMF are transferred via this NWt connection.
A reference point between the TNAP and the TNGF, which is used to support an AAA interface. Ta requirements are documented in clause 220.127.116.11.2
A reference point between two TNGFs, which is used to facilitate UE mobility between different TNGFs (inter-TNGF mobility).
Tn and inter-TNGF mobility are not specified in this Release of the specification.
Ta shall be able to
Carry EAP-5G traffic and user location information before the NWt connection is established between the UE and the TNGF.
Allow the UE and the TNGF to exchange IP traffic.
In deployments where the TNAP does not allocate the local IP addresses to UE(s), Ta shall be able to:
Allow the UE to request and receive IP configuration from the TNAN (including a local IP address), e.g. with DHCP. This is to allow the UE to use an IP stack to establish a NWt connection between the UE and the TNGF.
The "local IP address" is the IP address that allows the UE to contact the TNGF; the entity providing this local IP address is part of TNAN and out of 3GPP scope
In this Release of the specification, Ta is not specified.