Trace Recording Session Reference

Description

The Trace Recording Session Reference (TRSR) is a critical identifier within the 3GPP's network management, specifically defined in the context of the Trace Control and Configuration Management Service (TCCMS) and the broader Management Data Analytics (MDA) framework. It serves as a unique key that unambiguously identifies an active or historical trace recording session initiated by the network operator. A trace recording session is a controlled process where specific network functions (e.g., Access and Mobility Management Function (AMF), Session Management Function (SMF), gNB) or User Equipment (UE) are instructed to collect and log detailed, granular data about signaling procedures, user plane activities, performance measurements, or specific events.

Architecturally, the TRSR is generated and managed by the Trace Control Function, often residing within the Operations, Administration and Maintenance (OAM) system or the Network Data Analytics Function (NWDAF). When an operator or an automated analytics function decides to initiate a trace—for example, to diagnose a service degradation for a specific subscriber or to monitor performance in a particular network slice—it sends a trace activation request. Upon successful activation, the managing function assigns a unique TRSR to this session. This TRSR is then included in all subsequent management communications related to this trace. It is used when the collecting network functions (trace collection entities) report the captured trace data (Trace Records) back to a central Trace Collection Entity. The TRSR allows the system to correctly associate all incoming trace records with the correct session context.

The TRSR works in conjunction with other trace parameters like Trace Reference, Trace Depth, and Interfaces To Trace. It is a cornerstone for trace session lifecycle management: activation, modification, deactivation, and retrieval. Logs and records stored in the trace collection archive are indexed by the TRSR, enabling efficient querying and analysis. In 5G service-based architecture, the TRSR is used in service operations defined in services like Nnrf_NFManagement, where NF service consumers can subscribe to trace data notifications filtered by TRSR. The identifier ensures data isolation and security, as trace data is often sensitive, containing subscriber-related information. Its structured format allows for scalability in large networks where thousands of concurrent trace sessions may be active across different domains (5GC, NG-RAN).

Purpose & Motivation

The TRSR was introduced to solve the problem of managing and correlating the vast amounts of diagnostic data generated by distributed trace sessions in modern, complex telecom networks. Prior to its formal definition, trace management was more ad-hoc and vendor-specific, making it difficult for operators to consistently activate traces across multi-vendor networks and to collate data from different network elements for a unified view of a service issue or subscriber journey.

Its creation was motivated by the need for standardized, automated network troubleshooting and optimization in 3GPP networks, particularly with the rollout of LTE and the increased complexity of the core network. The TRSR provides a standardized 'handle' that OAM systems and emerging analytics functions (like the NWDAF in 5G) can use to programmatically control and consume trace data. This is essential for implementing closed-loop automation, where the network can self-diagnose problems: an analytics function detects an anomaly, automatically activates a trace session (receiving a TRSR), collects the data, analyzes it, and then takes corrective action, all using the TRSR as the session identifier.

Furthermore, with the advent of network slicing in 5G, the ability to trace activities within a specific slice without interfering with others is crucial. The TRSR, used in conjunction with slice identifiers, enables slice-aware tracing. It also supports regulatory requirements like Lawful Interception (LI) by providing a managed framework for activating targeted traces, though LI uses its own specific identifiers and interfaces. In summary, the TRSR is a foundational enabler for efficient, scalable, and automated network observability and management in the 3GPP ecosystem.

Key Features

• Globally unique identifier for a network trace recording session within the management domain
• Enables correlation of trace records collected from multiple distributed network functions and UEs
• Central to the lifecycle management (activation, modification, deactivation) of trace sessions
• Used in service-based interfaces (e.g., Nnrf) for subscribing to and retrieving trace data
• Supports targeted tracing for specific subscribers, areas, slices, or services
• Essential for automated troubleshooting and Management Data Analytics (MDA) workflows

Evolution Across Releases

Defining Specifications