GPRS Tunneling Protocol (GTP) is a group of IP-based communications protocols used to carry General Packet Radio Service (GPRS) within Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) networks. GTP employs tunneling to transport GPRS packets over IP networks. This tunneling allows users to move between SGSNs and still maintain connection to the Internet through the GGSN.
GTP has three versions version 0, 1, and 2. GTPv1 and GTP2v are supported by FortiOS Carrier. The only GTP commands that are common to all forms of GTP are the echo request/response commands that allow GSNs to verify up to once every 60 seconds that neighboring GSNs are alive.