The functionality of W-AGF in the case of Wireline 5G Access network includes the following:
Termination of N2 and N3 interfaces to 5G Core Network for control - plane and user-plane respectively.
Handling of N2 signalling from SMF (relayed by AMF) related to PDU Sessions and QoS.
Relaying uplink and downlink user-plane packets between the 5G-RG and UPF and between FN-RG and UPF. This involves:
Enforcing QoS corresponding to N3 packet marking, taking into account QoS requirements associated to such marking received over N2.
N3 user-plane packet marking in the uplink.
Supporting AMF discovery and selection defined in clause 6.3.5 of TS 23.501 where the 5G-S-TMSI is not used for AMF selection since the wireline AS layer can only carry the GUAMI.
Termination of wireline access protocol on Y4 and Y5.
In the case of FN-RG the W-AGF acts as end point of N1 on behalf of the FN-RG.
In the case of Wireline 5G Broadband Access network the definition of W-AGF functionalities is specified in BBF TR-456  and WT-457 .
In the case of Wireline 5G Cable Access network the definition of W-AGF functionalities is specified by Cablelabs WR-TR-5WWC-ARCH .