PDU layer: This layer corresponds to the PDU carried between the UE and the DN over the PDU Session. When the PDU Session Type is IPv4 or IPv6 or IPv4v6, it corresponds to IPv4 packets or IPv6 packets or both of them; When the PDU Session Type is Ethernet, it corresponds to Ethernet frames; etc.
GPRS Tunnelling Protocol for the user plane (GTP-U): This protocol supports tunnelling user data over N3 (i.e. between the 5G-AN node and the UPF) and N9 (i.e. between different UPFs of the 5GC) in the backbone network, details see TS 29.281. GTP shall encapsulate all end user PDUs. It provides encapsulation on a per PDU Session level. This layer carries also the marking associated with a QoS Flow defined in clause 5.7. This protocol is also used on N4 interface as defined in TS 29.244.
5G-AN protocol stack: This set of protocols/layers depends on the AN:
When the 5G-AN is a 3GPP NG-RAN, these protocols/layers are defined in TS 38.401. The radio protocol between the UE and the 5G-AN node (eNodeB or gNodeB) is specified in TS 36.300 and TS 38.300.
When the AN is an Untrusted non 3GPP access to 5GC the 5G-AN interfaces with the 5GC at a N3IWF defined in clause 4.3.2 and the 5G-AN protocol stack is defined in clause 8.3.2.
UDP/IP: These are the backbone network protocols.
If there is an UL CL (Uplink Classifier) or a Branching Point (both defined in clause 5.6.4) in the data path of a PDU Session, the UL CL or Branching Point acts as the non PDU Session Anchor UPF of Figure 8.3.1-1. In that case there are multiple N9 interfaces branching out of the UL CL / Branching Point each leading to different PDU Session anchors.
Large GRE packets may be fragmented by the "inner IP" layer.
Details about the PDU Layer, the N3 stack and the N9 stack are included in clause 8.3.1. The UDP protocol may be used below the IPsec layer to enable NAT traversal.
Large GRE packets may be fragmented by the "inner IP" layer.
Details about the PDU Layer, the N3 stack and the N9 stack are included in clause 8.3.1. The UDP protocol may be used below the IPsec layer to enable NAT traversal.
Details about the PDU Layer, PDU Session User Plane Protocol Stack are included in clause 8.3.1 and clause 8.3.2. The N19 is based on a shared User Plane tunnel connecting two PSA UPFs of a single 5G VN group.
Transport: this layer refers to the transport of PDUs between the N5CW device and TWIF (see clause 4.2.8.5.4).
In this Release of the specification, Trusted WLAN Access for N5CW Device only supports IP PDU Session type.