User-plane gateway that routes and forwards user data packets in LTE/EPC.
Description
The Serving Gateway (S-GW) is a user-plane node that routes and forwards user data packets through the LTE network. It acts as the local mobility anchor for inter-eNodeB handover and provides connectivity to the P-GW.
The S-GW terminates the S1-U interface from the E-UTRAN and routes traffic between the radio network and the P-GW. It maintains data paths for both idle and active UEs.
Purpose & Motivation
The S-GW was designed as part of LTE's flat architecture to handle user-plane traffic separately from control-plane signaling. This separation allows for:
- Efficient local routing during handovers - Lawful interception capabilities - Charging data collection - Mobility anchor point for 3GPP access
Key Features
- ✓Local mobility anchor
- ✓Packet routing and forwarding
- ✓Charging support
- ✓Lawful interception
- ✓UL/DL charging per UE/bearer