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5G LAN-type service Introduction

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Author: Yuan-Ting Chen
Date: 2025/01/22

5G LAN-type Services

5G LAN-type service provides services with similar functionalities to Local Area Networks (LANs) and VPN’s but improved with 5G capabilities such as high performance, long distance access, mobility and security.

For instance, Automated Guided Vehicles (AGVs) moving inside a large factory may communicate and cooperate through 5G LAN technology with low latency. This could be hard to achieve through Wi-fi due to the possibility of handover issue.

5G VN Group

Tip

Definitions
5G LAN-virtual network (5G LAN-VN): a virtual network capable of supporting 5G LAN-type service.
5G VN Group: A set of UEs using private communication for 5G LAN-type service.

5G VN group management

A 5G VN group is characterized by the following:

  • 5G VN group identities:
    used to identify the 5G VN group.
    • External Group ID
    • Internal Group ID
  • 5G VN group membership:
    used to uniquely identify 5G VN group members.
    • GPSIs
  • 5G VN group data
    • PDU session type
    • DNN
    • S-NSSAI
    • Application descriptor
    • Information related with secondary authentication / authorization (e.g. to enable IP address assignment by the DN-AAA).

The 5G VN groups and 5G VN members are managed (e.g. add/delete/modify) via a set of services exposed by NEF.

5G VN group creation

VN group management procedure 1

  • A 5G VN group is identified by the AF using External Group ID.
  • The NEF provides the External Group ID to UDM.
  • The UDM maps the External Group ID to Internal Group ID.
    For a newly created 5G VN Group, an Internal Group ID is determined by the UDM.

After the 5G VN group is created, UE with corresponding DNN and S-NSSAI would get the UE policy associated with the 5G VN group in the registration procedure.

VN group management procedure 2

  • After Registration Accept in the General Registration Procedure, the AMF performs a UE Policy Association Establishment procedure.
  • In the UE Policy Association Establishment procedure, the AMF sends a Npcf_UEPolicyControl Create Request, which contains the Internal-Group-ID-list of the UE and UE Policy Container, to PCF.
  • The PCF then get the 5G VN group data and 5G VN group membership for each Internal-Group-ID received from the AMF using Nudr_DM_Query (Internal-Group-Id, Subscription Data, 5G VN Group Configuration).

VN group management procedure 3

  • The PCF triggers UE Configuration Update Procedure to update UE policy and sends the UE policy container including UE policy information to the UE.
  • PCF invokes Namf_Communication_N1N2MessageTransfer service operation provided by the AMF. The message includes SUPI, UE Policy Container.
  • the AMF transfers transparently the UE Policy container (UE policy information) received from the PCF to the UE using DL NAS TRANSPORT message.

5G VN Group Communication

There are three types of traffic forwarding methods allowed for 5G VN communication:

  • Local switch, where traffic is locally forwarded by a single UPF if this UPF is the common PSA UPF of different PDU Sessions for the same 5G VN group.

user plane architechture local switch

  • N19-based, where the UL/DL traffic for the 5G VN group communication is forwarded between PSA UPFs of different PDU sessions via N19. N19 is based on a shared User Plane tunnel connecting PSA UPFs of a single 5G VN group.

    user plane architechture N19-based

  • N6-based, where the UL/DL traffic for the 5G VN communication is forwarded to/from the DN;

Traffic forwarding within the 5G VN group is realized by using a UPF internal interface ("5G VN internal")

Reference

  • TS 22.261 "6.26 5G LAN-type service"
  • TS 23.501 "4.4.6 5G LAN-type Services"
  • TS 23.501 "5.29 Support for 5G LAN-type service"
  • TS 23.502 "4.15.6.2 NEF service operations information flow"
  • TS 23.502 "4.2.2.2.2 General Registration"
  • TS 23.502 "4.16.11 UE Policy Association Establishment"
  • TS 23.502 "4.2.4.3 UE Configuration Update procedure for transparent UE Policy delivery"

About me

Hi, I’m Yuan-Ting Chen, a newcomer to 5G and free5GC. I'm currently conducting research on 5G LAN. Please feel free to let me know if there is any mistake in the article.