Description
A Packet Flow Description (PFD) is a data object used within 3GPP's policy and charging control framework to enable application-aware network management. Its primary purpose is to provide the User Plane Function (UPF) or Traffic Detection Function (TDF) with the necessary information to detect traffic belonging to a specific application, such as a video streaming service or a social media app. A PFD is not a rule itself but the descriptive input used to create Packet Detection Rules (PDRs) within the PFCP protocol. A PFD typically contains an application identifier (e.g., a standardized 3GPP App ID or a custom identifier) and one or more packet filters.
These packet filters can be defined at different layers of the protocol stack to allow for flexible and efficient detection. They may include domain names, URLs, URI patterns, or traditional 3-tuple/5-tuple IP information (source/destination IP address, protocol, port numbers). For example, a PFD for a video service might include the domain name of its content delivery network and specific URL patterns for video segments. The entity responsible for PFD management, such as the Policy Control Function (PCF) or an Application Function (AF), provisions these PFDs to the SMF via the N5/N7 interface. The SMF then translates the PFDs into actionable Packet Detection Rules (PDRs) and installs them into the relevant UPF using the PFCP protocol.
Once installed, the UPF uses these derived rules to inspect packets. When a match is found, the UPF can apply the appropriate policy, such as steering the traffic to a specific edge server, applying QoS prioritization, triggering charging events, or blocking the flow. This mechanism is crucial for service differentiation, network optimization, and parental controls. The PFD framework also includes procedures for PFD management, allowing the PCF to provision, update, or remove PFDs dynamically, enabling real-time adjustment to the network's application detection capabilities as new services emerge or traffic patterns change.
Purpose & Motivation
The Packet Flow Description was developed to address the challenge of effectively identifying and managing the exploding variety of Over-The-Top (OTT) application traffic in mobile networks. Traditional policy control relied heavily on static, operator-defined rules based on IP addresses and port numbers, which became ineffective as applications used dynamic ports, encrypted protocols (like HTTPS), and shared content delivery networks, obscuring their identity.
PFDs provide a standardized, flexible method for describing application traffic beyond the limited 5-tuple. By incorporating application-layer identifiers like domain names and URL patterns, they enable much more accurate traffic detection. This accuracy is fundamental for implementing advanced policies like sponsored data (where an application provider pays for the data usage), application-specific QoS boosting (e.g., prioritizing a partner's video service), and intelligent traffic steering to local breakouts or edge caches. The PFD framework, introduced as part of enhanced policy control, empowers operators and third-party service providers to collaborate in creating application-aware networks, moving from managing anonymous IP pipes to managing recognized services and user experiences.
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (75 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the PFD (Packet Flow Description) function was introduced, enabling the NEF's PFD Function to provide PFDs to the SMF via pull or push modes. The release specified that the SMF caches PFDs and provisions them to the UPF, and introduced the capability for the NEF to subscribe to NWDAF for PFD determination analytics to inform PFD management decisions.
- Corrections to PFD management TS 23.501CR0210
- Corrections to PFD management descriptions TS 23.503CR0067
- Procedure correction of PFD management error handling TS 29.122CR0022
- Complete the openAPI definition for PFD API TS 29.122CR0023
- Removable attribute definition for PFD management TS 29.122CR0041
- Correct PFD error code TS 29.122CR0042
+ 13 more changes
In Release 16, the PFD function introduced enhanced management capabilities including partial failure handling and notifications, extended PFD attributes to support multiple values and domain name protocols, and refined procedures for AF-initiated management and NEF discovery. It also removed the NEF pre-configuration option for PFD push and corrected the handling of the Allowed Delay parameter. Furthermore, the release aligned the PFD change subscription mechanism using PUT and corrected various presence conditions and notification procedures.
- PFD management notification TS 29.122CR0171
- PFD management partial failure TS 29.122CR0196
- PFD partial failure notification TS 29.122CR0212
- PFD extension TS 29.250CR0012
- PFD management notification TS 29.250CR0018
- PFD partial failure notification TS 29.250CR0019
+ 16 more changes
In Release 17, the enhancements for the Packet Flow Description (PFD) function introduced a PATCH method for updating PFD management transaction resources and added support for feature negotiation during PFD data retrieval. The release also included the new parameter "allowedDelay" for PFD data and provided corrections and clarifications to procedures for PFD retrieval, change subscription modification, and notification handling in both pull and push modes.
- Support PATCH for the update of a PFD Management Transaction resource TS 29.122CR0571
- Correction to PFD procedures TS 29.513CR0298
- Correction to PFD retrieval procedure TS 29.513CR0312
- Feature negotiation at PFD data retrieval TS 29.519CR0288
- Support of allowedDelay for PFD data TS 29.519CR0327
- Handling of query parameters for PFD Data TS 29.519CR0334
+ 6 more changes
In Release 18, the PFD (Packet Flow Description) function was enhanced to introduce NWDAF-assisted PFD management, where the NEF (PFDF) can subscribe to or request PFD "Determination analytics" from the NWDAF to inform decisions on creating, updating, or deleting PFDs. This release specifically added support for these PFD Determination Analytics through the Nnwdaf_AnalyticsInfo and Nnwdaf_EventsSubscription APIs, and introduced the capability for the NWDAF to fetch PFD information via the Nnef_PFDmanagement API. Furthermore, new attributes like confidence levels were added to the analytics, and clarifications were provided for the associated service operations and procedures.
- PFD Determination Analytics for Nnwdaf_AnalyticsInfo API TS 29.520CR0624
- Support PFD Determination Analytics in Nnwdaf_EventsSubscription API TS 29.520CR0680
- Update PFD Determination Analytics for Nnwdaf_AnalyticsInfo API TS 29.520CR0692
- Adding confidence attributes to PFD Determination Analytics TS 29.520CR0791
- Enhancement of PFD Determination analytics TS 29.520CR0858
- Updates to PFD Determination Analytics TS 29.520CR0869
+ 14 more changes
In Release 19, the PFD function was enhanced with new capabilities for analytics-driven management and updates to provisioning procedures. Specifically, the NEF (PFDF) can now subscribe to or request "Determination analytics" from the NWDAF to inform decisions on creating, updating, or deleting PFDs. Furthermore, the specifications detail improved management for ensuring the SMF provisions updated PFDs to the UPF without overloading N4 signaling and clarifies the behavior when PFDs are overwritten or removed.
Explore further
Broader topics and technologies where PFD plays a role.
Defining Specifications
3GPP specifications that define or reference PFD, 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 23.503 vk00 | 5G Policy and Charging Control Framework | Rel-20 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TS 26.512 vj10 | 5G Media Streaming Protocols & APIs | Rel-19 |
| TS 26.804 vj10 | 5G Media Streaming Extensions Study | Rel-19 |
| TS 29.122 vj40 | T8 Reference Point for Northbound APIs | Rel-19 |
| TS 29.212 vj00 | Gx/Gxx/Sd/St Diameter Protocol | Rel-19 |
| TS 29.244 vj40 | PFCP Specification for Control/User Plane Separation | Rel-19 |
| TS 29.250 vj00 | Nu Reference Point Stage 3 Specification | Rel-19 |
| TS 29.251 vj00 | Gw/Gwn Reference Points Stage 3 Specification | Rel-19 |
| TS 29.510 vj50 | NRF Service Based Interface Protocol | Rel-19 |
| TS 29.512 vj40 | 5G Session Management Policy Control Service | Rel-19 |
| TS 29.513 vj40 | 5G PCC Signalling Flows & QoS Mapping | Rel-19 |
| TS 29.519 vj40 | UDR Usage for Policy & Exposure Data | Rel-19 |
| TS 29.520 vj40 | 5G Network Data Analytics Services Stage 3 | Rel-19 |
| TS 29.522 vj40 | 5G NEF Northbound APIs Stage 3 | Rel-19 |
| TS 29.551 vj30 | 5G PFD Management Service Stage 3 | Rel-19 |
| TS 38.101 vj31 | NR User Equipment Radio Transmissions | Rel-19 |
