GGSN Function

Description

The GgsnFunction is a managed object defined in the Generic Network Resources NRM of 3GPP TS 28.703. It represents a GGSN (Gateway GPRS Support Node) function within the GPRS core network. The GGSN is a critical node that acts as the gateway between the GPRS network and external packet data networks (PDNs) such as the Internet, corporate intranets, and other service networks. It is responsible for IP address allocation, session management, and policy enforcement for GPRS sessions. In the 3GPP management architecture, the GgsnFunction object allows the network management system to model, configure, and monitor GGSN functions. It is derived from the GenericNetworkResourcesNRMDefs::ManagedFunction base class, inheriting common attributes such as identifier, administrative state, and operational state.

The GGSN function itself is a logical entity that may be implemented on dedicated hardware or as a virtualized network function (VNF). It communicates with the SGSN (Serving GPRS Support Node) over the Gn interface and with external PDNs over the Gi interface. The GGSN is responsible for establishing and maintaining PDP (Packet Data Protocol) contexts, which are the GPRS equivalent of data sessions. It allocates IP addresses to mobile stations, enforces QoS policies, and performs charging functions. The GgsnFunction managed object represents the GGSN's capabilities and configuration, including its supported interfaces, IP address pools, and QoS profiles.

The GgsnFunction is defined in TS 28.703, which specifies the Generic Network Resources NRM for GERAN and GPRS. The companion specification TS 32.636 defines the corresponding IRP information service, which specifies the operations that can be performed on the GgsnFunction object. These operations include creating, deleting, and modifying GgsnFunction instances, as well as retrieving their attributes and status. The management system uses these operations to configure the GGSN, monitor its performance, and detect faults.

In terms of architecture, the GgsnFunction object is typically instantiated under a ManagedElement that represents a GGSN node. It may be associated with other objects such as a GgsnFunctionSet or a GgsnInterface object that groups multiple functions. The GgsnFunction object also supports the concept of a 'generic' function, meaning it can represent a GGSN function without requiring full details of the underlying implementation. This is useful in multi-vendor environments where the GGSN may be implemented differently by different vendors. The object's attributes include the function's operational state, which indicates whether the function is currently active, and the administrative state, which allows the operator to enable or disable the function.

From a practical standpoint, the GgsnFunction is used in the management of GPRS and EDGE networks, as well as in the management of 3G networks where the GGSN is used for packet-switched services. It enables operators to manage the GGSN efficiently, ensuring that packet data services are delivered reliably. The object also plays a role in the transition to 4G and 5G, where the GGSN's functions are distributed across multiple network functions such as the PGW (Packet Data Network Gateway) and SMF (Session Management Function). As networks evolve, the GgsnFunction object may be used in conjunction with newer management objects to ensure backward compatibility and smooth migration.

Purpose & Motivation

The GgsnFunction managed object exists to provide a standardized way to manage the GGSN in GPRS and UMTS networks. The GGSN is a critical node that provides connectivity to external packet data networks, and its management is essential for ensuring service quality and network reliability. Before the introduction of the Generic Network Resources NRM, the management of GGSNs was often vendor-specific, leading to interoperability challenges and increased operational costs. The GgsnFunction object addresses this by providing a standardized representation that can be used across different vendors' equipment.

The GgsnFunction object also solves the problem of managing the GGSN in multi-vendor and multi-technology environments. In a typical GPRS network, the GGSN may be from a different vendor than the SGSN, and the external PDNs may use various protocols. The GgsnFunction object abstracts these details, allowing the management system to configure and monitor the GGSN without needing to know the specifics of the underlying implementation. This abstraction simplifies management and reduces the risk of configuration errors.

Historically, the GGSN was introduced with GPRS in the late 1990s. As GPRS evolved to EDGE and later to 3G, the GGSN continued to be used. The need for standardized management became apparent as networks grew in size and complexity. The Generic Network Resources NRM, introduced in Release 10, provided a unified framework for managing various network resources, including the GGSN. The GgsnFunction object is a key part of this framework, enabling operators to manage the GGSN efficiently and consistently. As networks evolve towards 5G, the GGSN's functions are being distributed, but the GgsnFunction object remains relevant for legacy networks and for managing the transition.