FAR

FAR

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Introduced in Rel-14 Also in: Core Network

FAR is the 3GPP forwarding action rule that defines how a User Plane Function handles packets, specifying actions like forwarding, buffering, or dropping.

Category
Other
Introduced
Rel-14
Where
Radio Access Network › NG-RAN (5G)
Also touches
1 segments
Specifications
9 specs
FAR Description Purpose Detected Changes Specifications

Description

Forwarding Action Rule

Purpose & Motivation

Detected Changes Across Releases

from 3GPP Change Requests

Specific changes extracted from the „Change history“ tables of 3GPP specifications (8 CRs across 3 releases). Complements the general historical overview above with the evidence-based evolution of this function.

Studied in Rel-14, normative work from Rel-15.

Rel-15 3 changes

In Release 15, the Forwarding Action Rule (FAR) was newly introduced as a core user-plane control element for the SMF to instruct the UPF via N4 on packet forwarding, dropping, duplicating, or buffering. The FAR's defined attributes enable specific actions like Outer Header Creation for tunneling and support for HTTP Redirection. Furthermore, its capabilities were extended to include functionalities such as IP Address and Port Number Replacement for Edge Application Server relocation and the inclusion of a Network Instance for interface determination within the UPF.

Rel-16 4 changes

In Release 16, the Forwarding Action Rule (FAR) function was enhanced to support new procedures and clarifications. Key additions included the activation of predefined FARs, the use of FARs for uplink traffic handling at a Uplink Classifier or Branching Point towards a Local PDU Session Anchor, and clarifications for FAR creation and modification. Furthermore, the specification detailed the inclusion of specific information elements like "IP Address and Port Number Replacement" and Network Instance within the FAR for advanced forwarding and interface determination.

  • Clarification to Create PDR/FAR/URR/QER/BAR/MAR IEs in a modification message TS 29.244CR0295
  • UL FAR in UL CL or BP towards Local PSA TS 29.244CR0297
  • Activating a predefined FAR/URR/QER TS 29.244CR0356
  • Clarification on the FAR ID for Quota Action TS 29.244CR0514
Rel-18 1 change

In Release 18, the FAR (Forwarding Action Rule) was enhanced to support quota exhaustion handling by being substituted when a Volume Quota or a Time Quota is exhausted. Furthermore, the FAR's role in traffic steering was refined, as it can now carry Metadata received from the PCF for N6-LAN Traffic Steering Enforcement and can be configured to include specific "IP Address and Port Number Replacement" information for Edge Application Server relocation support.

  • Substitute FAR when exhausting a Volume Quota or a Time Quota TS 29.244CR0726

Defining Specifications

3GPP specifications that define or reference FAR, with the latest known release. Sourced from the 3GPP document catalog — see methodology.

SpecificationTitleRelease
TS 23.501 vk00 5G System Architecture Stage 2 Rel-20
TS 26.804 vj10 5G Media Streaming Extensions Study Rel-19
TS 29.244 vj40 PFCP Specification for Control/User Plane Separation Rel-19
TS 38.113 vj00 NR Base Station EMC Specification Rel-19
TS 38.191 vj00 NR Ambient IoT RF Characteristics Rel-19
TS 38.769 vk00 Ambient IoT Solutions in NR Rel-20
TS 38.774 vj00 Rel-19 LP-WUS/WUR RF Requirements TR Rel-19
TS 38.821 vg20 NR Support for Non-Terrestrial Networks Rel-16
TR 38.869 vi00 Study on low-power wake up signal and receiver for NR Rel-18