GPRS Tunnelling Protocol User Plane (GTP-U)
GTP-U is the protocol that carries users' data through tunnels across the interfaces of a mobile network.
What is GPRS Tunnelling Protocol User Plane (GTP-U)?
GTP-U wraps each user packet in a header that identifies its tunnel and sends it over UDP/IP between network nodes, for example between the base station and the user plane function. The network can then move a user's traffic around while keeping each session separate.