Description
Network Requested Support Network (NRSN) is a functional concept in 3GPP core networks that enables one network (the requesting network) to solicit assistance or services from another network (the supporting network). This typically occurs in scenarios like inter-PLMN (Public Land Mobile Network) roaming, where a visited network requires support from the home network for subscriber authentication, authorization, and billing. The mechanism is implemented through standardized interfaces and protocols, such as the Gp interface between Gateway GPRS Support Nodes (GGSNs) in different PLMNs or the N9 interface in 5G between User Plane Functions (UPFs). When a User Equipment (UE) attaches or initiates a session in a visited network, the visited network's core elements (e.g., SGSN in GPRS or AMF in 5G) may send a request to the home network's elements (e.g., HLR/HSS or AUSF) to verify credentials and retrieve subscriber profiles. This request triggers the NRSN procedure, where the home network provides the necessary support, such as sending authentication vectors or policy rules. The process involves secure signaling exchanges, often using Diameter or HTTP/2 protocols, to ensure data integrity and confidentiality. NRSN also extends to other support functions like lawful interception, emergency services coordination, or quality of service (QoS) negotiation between operators. It is a cornerstone of global mobility, allowing seamless service delivery across administrative boundaries by enabling networks to dynamically request and provide support based on real-time needs.
Purpose & Motivation
The purpose of Network Requested Support Network (NRSN) is to address the challenges of interoperability and service continuity in multi-operator environments, particularly for roaming and inter-network collaboration. Before standardization, operators relied on bilateral agreements and proprietary methods for support, leading to inefficiencies, security risks, and limited scalability. NRSN was created to provide a unified, standardized framework for networks to request and deliver support services, ensuring consistent behavior across different vendors and regions. It solves problems like subscriber authentication in visited networks, where the home network must validate credentials without direct user intervention, enabling secure global roaming. Additionally, it facilitates resource sharing, such as when a network needs additional capacity or specialized services from a partner network. The motivation stems from the growth of global mobile services, requiring robust mechanisms for inter-PLMN communication to support billing, policy enforcement, and regulatory compliance. By introducing NRSN in Release 7 and evolving it through subsequent releases, 3GPP enabled more efficient, secure, and scalable inter-operator operations, enhancing user experience and network reliability.
Key Features
- Enables inter-PLMN support requests for roaming and services
- Uses standardized interfaces like Gp and N9 for signaling
- Supports authentication, authorization, and billing between networks
- Facilitates secure signaling with protocols like Diameter and HTTP/2
- Extends to lawful interception and emergency services coordination
- Provides dynamic resource and policy sharing across operator boundaries
Evolution Across Releases
Defining Specifications
| Specification | Title |
|---|---|
| TS 23.060 | 3GPP TS 23.060 |
| TS 29.060 | 3GPP TS 29.060 |