Description
Forwarding Action Rule
Purpose & Motivation
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific 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.
In Release 15, the Forwarding Action Rule (FAR) was newly introduced as a fundamental construct for the UPF, defining packet actions like forward, drop, duplicate, or buffer. The FAR is provisioned by the SMF via N4 procedures and contains attributes for forwarding operations, such as Destination Interface and Outer Header Creation for specific tunnels like N19. Its introduction also enabled support for new functionalities like HTTP Redirection and the conveyance of Metadata for traffic steering.
In Release 16, key enhancements to the Forwarding Action Rule (FAR) function included the ability to activate a predefined FAR and to use a FAR containing "IP Address and Port Number Replacement" information elements for Edge Application Server relocation. The release also provided clarifications on using FARs for uplink traffic at an Uplink Classifier or Branching Point towards a local PDU Session Anchor and on the handling of FAR IDs for quota actions. Furthermore, it specified that the SMF could provide a Network Instance to the UPF within a FAR for interface determination.
In Release 18, a key enhancement for the Forwarding Action Rule (FAR) was the ability for the SMF to substitute a FAR when a Volume Quota or a Time Quota is exhausted, as indicated by the new CR title. This builds upon the existing SMF control over user-plane packet forwarding via N4 interactions, where the FAR contains instructions for actions like forwarding, duplicating, or dropping packets. The release also continued to utilize the FAR for specific procedures such as EAS IP replacement and traffic steering within 5G VN groups, as detailed in the existing specification clauses.
- 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.
| Specification | Title | Release |
|---|---|---|
| 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 |
