pgw

PGW stands for Packet Gateway, also referred to as the PDN Gateway in 4G LTE networks. It is a core network element whose primary role is to provide connectivity between the mobile access network and external IP networks, including the Internet. The PGW serves as the anchor point for IP addresses and PDN connections for a user device, enabling services that require data access beyond the radio network.

The PGW performs several essential functions. It allocates and assigns IP addresses to user equipment (UE) for the duration of a PDN connection, handles routing and forwarding of user plane traffic to and from external networks, and enforces quality of service and policy decisions in coordination with policy control. It also supports charging and accounting through the collection of traffic data records, may perform packet filtering or basic firewall functions, and can provide network address translation when needed. The PGW interfaces with the Serving Gateway (SGW) to manage user plane traffic through the S5/S8 interfaces and connects to the external IP networks for data sessions.

Policy control and charging are typically integrated via the Gx interface to the Policy and Charging Rules Function (PCRF), usingDiameter-based signaling, to apply operator-defined rules for QoS, access control, and charging. The PGW often hosts multiple PDN connections (APNs) for different services or customers, allowing per-APN policy and address assignment.

In 5G networks, the role similar to the LTE PGW is fulfilled by the User Plane Function (UPF) within the 5G Core. The term PGW is primarily associated with LTE/EPC architectures and may still appear in discussions of evolution scenarios or interworking with legacy systems.

Deployment varies by operator, with multiple PGWs supporting different APNs, roaming arrangements, and scalability requirements.