Port 3386

Overview

GPRS Tunneling Protocol (GTP) is a group of IP-based protocols central to the operation of mobile data networks (2G, 3G, and LTE). It plays a key role in managing mobility and facilitating data transfer for mobile subscribers by encapsulating user data and signaling messages within tunnels.

GTP Components

• GTP-C (Control Plane): Handles signaling for session management, including creation, modification, and deletion of tunnels between network elements such as SGSN/MME and GGSN/PGW.
• GTP-U (User Plane): Responsible for actual user data transfer through encapsulated IP packets.
• GTP' (Prime): Utilized for charging data record transfer (billing).

GTP commonly operates over UDP port 3386, though it can support TCP, particularly in control plane contexts. It enables seamless user data flow when a subscriber is mobile, including during roaming scenarios where network elements from different operators communicate intensively.

How It Works

The subscriber’s device initiates a data session via the RAN (Radio Access Network). Network nodes use DNS to resolve the subscriber's APN (Access Point Name), establishing a GTP-C control tunnel. Once negotiated, a data tunnel (GTP-U) is set up through which user traffic is securely encapsulated and routed from the device to the public internet or enterprise services, underpinning modern mobile broadband connectivity.