Description
The Enhanced Gateway GPRS Support Node (E-GGSN) is a critical component within the 3GPP packet-switched core network architecture, specifically for GPRS and UMTS systems. It functions as the primary interface and gateway between the mobile operator's internal network and external Packet Data Networks (PDNs), such as the public internet, corporate intranets, or IP Multimedia Subsystem (IMS) services. Architecturally, it resides in the core network and connects to the Serving GPRS Support Node (SGSN) via the Gn/Gp interfaces and to external networks via the Gi interface. Its operation involves managing the lifecycle of Packet Data Protocol (PDP) contexts, which are logical data sessions established for a User Equipment (UE). When a UE initiates a data session, the SGSN communicates with the E-GGSN to create a PDP context. The E-GGSN is responsible for assigning an IP address to the UE (often via DHCP or from a local pool), authenticating the session (often in conjunction with AAA servers), and enforcing quality of service (QoS) policies and charging rules based on the user's subscription profile. It performs key network functions like routing user plane IP packets between the UE and the external network, applying traffic policing and shaping, and generating detailed charging data records (CDRs) for billing purposes. It also often integrates firewall and deep packet inspection (DPI) capabilities for security and service awareness. Its role is central to enabling mobile broadband internet access and ensuring secure, manageable connectivity.
Purpose & Motivation
The E-GGSN was introduced to enhance the capabilities of the standard GGSN defined in earlier 3GPP releases. The primary motivation was to support the increasing demands of mobile data services, which required more sophisticated traffic handling, improved QoS management, and enhanced charging mechanisms. As mobile networks evolved from basic GPRS to support higher-speed UMTS and eventually HSPA, the simple gateway functions of the original GGSN became insufficient. The enhanced version was designed to address limitations in scalability, service differentiation, and integration with evolving network architectures like the IMS. It solved problems related to handling diverse data services (e.g., streaming, VoIP, browsing) with different latency and bandwidth requirements by providing more granular policy and charging control (PCC). It also facilitated the introduction of access point names (APNs) for specific services and improved security features for interfacing with untrusted external networks. Historically, its creation was part of the broader 3GPP effort to transition mobile networks from being primarily circuit-switched voice carriers to robust, all-IP packet-switched platforms capable of delivering a wide array of multimedia services.
Key Features
- PDP context management for establishing and tearing down mobile data sessions
- IP address allocation and management for User Equipment
- Policy enforcement and QoS management based on subscriber profiles
- Generation of Charging Data Records (CDRs) for billing
- Routing and gateway functionality between the mobile core and external IP networks
- Integration with Policy and Charging Control (PCC) architecture for advanced service control
Evolution Across Releases
Introduced the Enhanced GGSN (E-GGSN) as part of the 3GPP Release 4 specifications. The initial architecture provided enhanced capabilities over the Rel-99 GGSN, focusing on improved support for all-IP core networks, better separation of control and user plane, and foundational features for more advanced QoS and charging. It laid the groundwork for integration with the evolving IMS architecture.
Defining Specifications
| Specification | Title |
|---|---|
| TS 21.905 | 3GPP TS 21.905 |