Description
The UE Route Selection Policy (URSP) is a cornerstone of the 5G system's ability to support diverse services with vastly different requirements through network slicing and concurrent access to multiple data networks. It is a structured policy, defined in 3GPP TS 23.503, that the Policy Control Function (PCF) provisions to the User Equipment (UE) via the Access and Mobility Management Function (AMF). The URSP consists of a prioritized list of URSP rules. Each rule contains two main components: a Traffic Descriptor and a list of Route Selection Descriptors (RSDs). The Traffic Descriptor defines the set of application traffic to which the rule applies. It can use criteria such as Destination Internet Protocol (IP) addresses/prefixes, port numbers, protocol IDs, Domain Name System (DNS) queries, or, most importantly, an OS/Application ID that directly identifies a specific application on the UE. The Route Selection Descriptor(s) then define the network resources that should be used for matching traffic. A single RSD can specify a combination of a Data Network Name (DNN), a Single-Network Slice Selection Assistance Information (S-NSSAI), and a Session and Service Continuity (SSC) mode. The UE's operating system or policy enforcement function evaluates these rules in priority order for each new application flow or socket connection. When a match is found, the UE uses the information in the RSD to establish a Protocol Data Unit (PDU) Session with the appropriate DNN and network slice, or to route the traffic over an existing matching PDU Session. This allows a single UE to have multiple active PDU Sessions—for example, one for enhanced Mobile Broadband (eMBB) to a public internet DNN, and another for Ultra-Reliable Low-Latency Communication (URLLC) to a private industrial network slice—with applications automatically mapped to the correct session. The URSP mechanism shifts significant intelligence to the UE, enabling dynamic, application-aware network resource selection without requiring constant network intervention for every flow.
Purpose & Motivation
URSP was created to address the fundamental challenge of efficiently supporting the 5G vision of a single network infrastructure catering to massively diverse use cases, from broadband to IoT to critical communications. Pre-5G networks primarily associated a UE with a single default data connection (PDN connection in 4G). While some form of dedicated bearers could provide different quality of service (QoS), the selection was network-controlled and limited in scope, lacking deep application awareness. URSP solves this by providing a flexible, programmable policy framework that allows the network operator to instruct the UE on how to map its myriad applications to the appropriate network slices and data networks. This enables simultaneous connectivity to multiple logical networks, optimal resource utilization, and seamless user experience where, for instance, a vehicle's telematics uses a low-latency slice while its infotainment uses a high-bandwidth slice. It was motivated by the need for automation and scalability; manually configuring each application on the UE or having the network micro-manage every flow is impractical. URSP empowers the UE to make intelligent local routing decisions based on operator-defined policies, which is essential for realizing the full economic and technical potential of network slicing and 5G service-based architecture.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (1463 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the URSP function was newly introduced to allow the network to provide the UE with policies for selecting access networks and PDU Sessions based on application traffic. Key foundational capabilities were specified, including the handling of S-NSSAI during inter-system mobility with EPS, the inclusion of connection capabilities within URSP rules, and the coding for WLAN selection criteria. Furthermore, the architecture defined how an application function, such as a SEALDD server, can interact with the policy framework to trigger the creation or update of URSP rules in the UE to establish redundant PDU Sessions.
- Additional PDU Session Type in Route Selection Descriptor TS 23.503CR0019
- Network policy indication on LTE call redirection to GERAN TS 24.301CR2951
- Handling of S-NSSAI and PDU session ID during mobility between EPS and 5GS TS 24.301CR2965
- Mode selection for inter-system change between EPS and 5GS TS 24.301CR2979
- Including S-NSSAI received in EPS in Requested NSSAI and in PDU session establishment request upon inter-system change from S1 mode to N1 mode TS 24.501CR0082
- Handling of error case when UE gets URSP from VPLMN TS 24.501CR0256
+ 200 more changes
In Release 16, the URSP function was enhanced to support Multi-Access (MA) PDU Sessions, allowing URSP rules to influence the establishment of PDU Sessions that can simultaneously use 3GPP and non-3GPP access. Furthermore, the release introduced mechanisms for the SEALDD server to initiate application guidance procedures with the 5G network to create or update URSP rules in the UE, specifically to establish redundant transmission paths for services like SEALDD-enabled data delivery.
- CIoT Introduction of CN Selection and Steering TS 23.501CR0896
- ATSSS-SMF and UPF selection TS 23.501CR0761
- Trusted non-3GPP Access Network Selection TS 23.501CR0783
- eSBA communication schemas related to general discovery and selection TS 23.501CR0799
- eSBA communication schemas related to UDM and UDR discovery and selection TS 23.501CR0800
- Use of analytics for SMF selection TS 23.501CR0940
+ 261 more changes
In Release 17, URSP enhancements were specifically introduced to support Application Function guidance for PCF determination of proper URSP rules, enabling the creation or update of policies based on external application input. This allowed for new procedures, such as the SEALDD server initiating application guidance for URSP determination to establish redundant transmission paths, resulting in the network providing updated URSP rules to the UE. Furthermore, the release clarified that the UE can provide a PDU Session Pair ID based on these URSP rules.
- NWDAF discovery and selection TS 23.501CR2575
- NWDAF discovery and selection based on provided ML models TS 23.501CR2585
- UP path selection enhancement based on analytics info provided by NWDAF TS 23.501CR2586
- NWDAF discovery and selection for model sharing TS 23.501CR2614
- KI #1-1, I-SMF selection TS 23.501CR2634
- Adding some parameters for local NEF selection TS 23.501CR2656
+ 277 more changes
In Release 18, URSP was enhanced to support policy control for multi-modal application flows, such as those requiring synchronization between individual SEALDD flows. Specifically, the network can now create or update URSP rules to establish redundant PDU Sessions for SEALDD-enabled services based on an Application Function request. Furthermore, URSP provisioning was extended to the EPS (Evolved Packet System) to ensure consistent policy delivery for 4G networks.
- N3IWF selection enhancement for support of S-NSSAI needed by UE TS 23.501CR3707
- Discovery and Selection of the NWDAF Supporting Federated Learning in 5GC TS 23.501CR3772
- KI#4 23.501 AF traffic influence for common EAS, DNAI selection TS 23.501CR3788
- Common EAS/DNAI selection by AF TS 23.501CR3789
- The support of Home Routed PDU Session supporting Session Breakout in VPLMN (HR-SBO) TS 23.501CR3830
- Policy control enhancements to support multi-modal flows TS 23.501CR3864
+ 519 more changes
In Release 19, the URSP function was enhanced to support policy-triggered redundant connection management for SEALDD services, where the SEALDD server can initiate the creation or update of URSP rules to establish two redundant PDU Sessions. Furthermore, URSP-related policies were expanded to include SEALDD policy configuration for multi-modal flows and the provisioning of a Geofence policy in the SEALDD server to allow or restrict connection establishment based on UE location. The release also introduced mechanisms for the update and deletion of SEALDD client policy configurations.
- Policy triggered redundant connection management TS 23.433CR0016
- Provisioning a Geofence policy in the SEALDD server TS 23.433CR0023
- SEALDD policy configuration for multi-modal flows TS 23.433CR0080
- Add update and delete service operation of SEALDD client policy configuration TS 23.433CR0128
- RVAS with target NF selection enhancement. TS 23.501CR5364
- NF discovery and selection by target PLMN TS 23.501CR5399
+ 165 more changes
In Release 20, URSP enhancements introduced new policy control capabilities for SEALDD-enabled services, including the enforcement of Data Delivery (DD) policies and geofence policies by the SEALDD server to control connection establishment. The release also specified mechanisms for the SEALDD server to trigger the creation or updating of URSP rules in the UE to establish redundant PDU Sessions for multi-modal or synchronized SEALDD flows. Furthermore, it added policy control based on abnormal user plane traffic analytics and integrated support for network energy saving policies.
- Support on the SEALDD policy enforcement. TS 23.433CR0194
- Energy Consumption information exposure and policy control TS 23.501CR6508
- Update on architecture and EIF function to support policy control for network energy saving TS 23.501CR6521
- Policy control based on abnormal user plane traffic analytics and traffic pattern analytics TS 23.503CR1599
- Service Adjustment based on Exposure - Policy TS 23.503CR1600
- Adding BDT, PDTQ and UE policy control for network energy saving TS 23.503CR1612
+ 5 more changes
Explore further
Broader topics and technologies where URSP plays a role.
Defining Specifications
3GPP specifications that define or reference URSP, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 23.433 vk00 | SEAL Data Delivery (SEALDD) for Verticals | Rel-20 |
| TS 23.501 vk00 | 5G System Architecture Stage 2 | Rel-20 |
| TS 23.503 vk00 | 5G Policy and Charging Control Framework | Rel-20 |
| TS 23.558 vk00 | Architecture for Edge Applications | Rel-20 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TR 23.758 vh00 | Study on Edge Application Architecture | Rel-17 |
| TS 23.791 vg20 | NWDAF Data Collection & Analytics Framework | Rel-16 |
| TS 24.193 vj50 | ATSSS Procedures Specification | Rel-19 |
| TS 24.301 vj60 | NAS protocol for Evolved Packet System | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.514 vj30 | Ranging & Sidelink Positioning in 5GS | Rel-19 |
| TS 24.526 vj30 | UE Policies for 5GS; Stage 3 | Rel-19 |
| TS 24.549 vj10 | SEAL Network Slice Capability Enablement Protocol | Rel-19 |
| TS 24.554 vj40 | 5G Proximity Services (ProSe) Protocols | Rel-19 |
| TS 26.501 vj30 | 5G Media Streaming (5GMS) Architecture | Rel-19 |
| TR 26.803 vh00 | 5G Media Streaming Extensions for Edge Processing | Rel-17 |
| TR 26.941 vj01 | 5G Media Slicing Extensions | Rel-19 |
| TS 29.507 vj40 | 5G Access & Mobility Policy Control Service | 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 29.514 vj40 | 5G System; Policy Authorization Service; Stage 3 | 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 29.523 vj20 | 5G Policy Control Event Exposure Service | Rel-19 |
| TS 29.525 vj40 | 5G UE Policy Control Service Stage 3 | Rel-19 |
| TS 29.890 vg00 | CT3 5G System Technical Report | Rel-16 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |
| TR 33.882 vi01 | Technical Report on 5G Security for Personal IoT Networks | Rel-18 |