5.28.5.1 General

5GS acts as a DetNet Router according to the architecture defined in clause 4.4.8.4. When integrated with an IETF Deterministic Network, 5GS acts as one or more routers. A 5GS router is composed of the ports on a single UPF (i.e. PSA) network side, the user plane tunnel between the UE and UPF and the ports on the device side. For each 5GS router of a deterministic network, the ports on the network side and the ports on device side that are associated to the PDU Sessions support connectivity to the deterministic network.

The granularity of the 5GS DetNet node is per UPF for each network instance or DNN/S-NSSAI. The TSCTSF stores the binding relationship between a device side port and a PDU Session identified by the UE address. The TSCTSF also stores information about ports on the UPF/NW-TT side.

The integration with IETF Deterministic Networking assumes the following.

• The existing 3GPP routing mechanisms are re-used for DetNet.
• The existing multicast capabilities can be re-used for DetNet communications.
• The 5GS integration to IETF DetNet is based on DetNet for IP; DetNet for MPLS is not supported.
• IPbased DetNet traffic is carried in IPtype PDU Sessions.
• 5GS functions realize the DetNet forwarding sub-layer. For the IP case, according to clause 1 of IETF RFC 8939 [157], no service sub-layer function needs to be defined. The 5GS DetNet Router acts as a DetNet transit node as defined in IETF RFC 8655 [150].

The interface between the TSCTSF and the DetNet controller uses protocols defined in IETF. The DetNet configuration is carried in the YANG model [154] over Netconf [155] or Restconf [156].