Internet Protocol Detail Record

Description

The Internet Protocol Detail Record (IPDR) is a comprehensive framework and data format defined by 3GPP for recording usage information in IP-based network services. It is a cornerstone of the 3GPP charging architecture, specifically within the Offline Charging System (OFCS). An IPDR is generated by network functions that provide or facilitate a service, such as the Gateway GPRS Support Node (GGSN), Packet Data Network Gateway (PGW), or Policy and Charging Rules Function (PCRF). Each record documents a discrete service usage event or session, providing a detailed, machine-readable account of what was consumed, by whom, when, and under what conditions.

The architecture of IPDR generation and transport involves several key components. The Charging Trigger Function (CTF), embedded within the network element (e.g., within a PGW), detects chargeable events based on predefined rules. When such an event occurs (e.g., IP-CAN session establishment, volume threshold reached, service data flow detected), the CTF collects relevant charging information and formats it into an IPDR. This IPDR is then streamed in near-real-time via the Rf reference point (for offline charging) to a Charging Data Function (CDF). The CDF validates, consolidates, and potentially correlates multiple IPDRs before forwarding them as Charging Data Records (CDRs) to a Charging Gateway Function (CGF) and ultimately to the network operator's Billing Domain.

An IPDR is composed of a structured set of fields defined in 3GPP TS 32.297. Its schema is extensible to accommodate various services (e.g., IMS, MMS, data connectivity). Common fields include a unique record identifier, the subscriber's identity (e.g., IMSI, MSISDN), the serving network element's address, session start/stop times, data volumes uploaded and downloaded, QoS parameters applied, rating group identifiers, and service-specific information. The format is designed to be unambiguous and complete, ensuring that the billing system has all necessary information to apply the correct tariff.

How IPDRs work is integral to modern usage-based billing. For example, during a user's mobile data session, the PGW may generate an IPDR at session start, interim IPDRs at specific volume intervals (e.g., every 10MB), and a final IPDR at session termination. This stream of records provides a granular trail of usage. The protocol for transferring these records (the IPDR Streaming Protocol) ensures reliable, ordered delivery from the CTF to the CDF. The role of IPDR is thus to provide the raw, factual data about network resource consumption, which is the essential input for all subsequent charging, billing, analytics, and fraud management processes in a telecom operator's business ecosystem.

Purpose & Motivation

IPDR was created to address the critical need for a standardized, flexible, and reliable mechanism to capture usage data in increasingly complex IP-based telecom services. Prior to its standardization, vendors and operators often used proprietary formats for usage records, leading to interoperability challenges, high integration costs, and limited flexibility for introducing new services. As 3GPP networks evolved beyond simple voice calls to offer packet-switched data, IMS multimedia services, and differentiated QoS, the charging data required became vastly more complex than traditional call detail records (CDRs) for circuit-switched voice.

The motivation for IPDR stemmed from the commercial necessity to monetize these new IP services accurately and efficiently. Operators needed to support various billing models: volume-based, time-based, event-based, and service-specific. A standardized detail record format was essential to enable multi-vendor networks, where a GGSN from one vendor must send usage data to a charging system from another. IPDR provided this common language. It solved the problem of how to represent heterogeneous service usage (web browsing, video streaming, IMS call) in a homogeneous, structured record that downstream billing and analytics systems could process automatically.

Introduced in Release 8, IPDR was part of a broader overhaul of the 3GPP charging architecture to support the All-IP network vision of EPS (Evolved Packet System). It replaced and generalized earlier, less flexible record formats. By providing a streaming interface (Rf) and a well-defined schema, it enabled near-real-time data collection, which was crucial for timely billing, spending limit control, and real-time analytics. Its creation was driven by the requirement to decouple network evolution from billing system evolution, allowing new services to be deployed without necessarily modifying the core billing infrastructure, as long as they could generate compliant IPDRs.

Key Features

• Standardized, extensible XML-based schema for representing diverse service usage data
• Supports streaming transfer protocol (over Diameter Rf) for near-real-time record delivery
• Captures granular details: data volumes, session timestamps, subscriber IDs, QoS parameters, service identifiers
• Enables flexible charging models (volume, duration, event, combination)
• Fundamental component of the 3GPP Offline Charging System (OFCS)
• Provides vendor-agnostic interface between network elements and charging systems

Evolution Across Releases

Defining Specifications