What is PDN-GW / P-GW?
The PDN-GW (also written P-GW) is a core network element in the 4G LTE Evolved Packet Core (EPC) that provides the UE’s IP point of attachment to external packet data networks (PDN) such as the internet or enterprise intranets. The P-GW is responsible for IP address allocation, QoS enforcement, charging, traffic gating, and lawful intercept. In 5G architecture, the P-GW’s functions are replaced by the UPF (User Plane Function) and SMF (Session Management Function).
How Does PDN-GW / P-GW Work?
The P-GW sits at the border between the EPC and external networks. When a UE establishes a PDN connection, the P-GW allocates an IP address (IPv4, IPv6, or dual-stack), creates a GTP tunnel to the S-GW, and applies QoS rules received from the PCRF via the Gx interface. User plane traffic flows through GTP-U tunnels from eNB → S-GW → P-GW → PDN. The P-GW applies traffic flow templates (TFTs) to classify and prioritize packets, performs deep packet inspection for charging, and enforces usage limits. In 5G NSA (EN-DC), the P-GW continues to serve as the IP anchor for the combined LTE+NR data session.
Use Cases
4G LTE internet connectivity and IP address assignment, mobile data charging and policy enforcement, enterprise APN/PDN connectivity, 5G NSA user plane anchoring, and roaming data traffic routing via home-routed or local breakout configurations.
3GPP / Standards Reference
3GPP TS 23.401 (GPRS enhancements for E-UTRAN — P-GW functions), 3GPP TS 29.274 (GTPv2-C for S5/S8 interface)
Related Terms
EPC | S-GW | UPF | SMF | Core Network
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
