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    GPRS Tunneling Protocol (GTP) Overview

    The GPRS Tunneling Protocol (GTP) is the tunneling protocol defined by the 3GPP standards to carry General Packet Radio Service (GPRS) within 3G/4G networks.

    GTP is used to establish a GTP tunnel, for user equipment, between a Serving Gateway (S-GW) and Packet Data Network Gateway (P-GW), and an S-GW and Mobility Management Entity (MME). A GTP tunnel is a channel between two GPRS support nodes through which two hosts exchange data. The S-GW receives packets from the user equipment and encapsulates them within a GTP header before forwarding them to the P-GW through the GTP tunnel. When the P-GW receives the packets, it decapsulates them and forwards them to the external host.

    GTP comprises the following separate protocols:

    • GTP-C— Performs signaling between the S-GW and P-GW in the core GPRS network to activate and deactivate subscriber sessions, adjust the quality of service parameters, or update sessions for roaming subscribers who have arrived from another S-GW. GTP-C supports transport of control packets in IPv4 format.
    • GTP-U— Transports user data within the core GPRS network and between the Radio Access Network (RAN) and the core network. GTP-U supports IPv4 and IPv6 user data, but transport is IPv4.

    Published: 2011-11-17