9 Path Protocols

09.603GPPGeneral Packet Radio Service (GPRS)GPRS Tunnelling Protocol GPT) across the Gn and Gp InterfaceRelease 1998TS

9.1 UDP/IP

UDP/IP is the only path protocol defined to transfer GTP signalling messages in this, the first version of GTP. UDP/IP is also the recommended choice as a connection-less path to tunnel connection-less T-PDUs. A User Datagram Protocol (UDP) compliant with STD 0006 shall be used.

9.1.1 UDP Header

9.1.1.1 Signalling request messages

The UDP Destination Port is the server port number 3386 . It shall be reserved for GTP.

The UDP Source Port is a locally allocated port number at the sending GSN.

9.1.1.2 Signalling response messages

The UDP Destination Port value shall be the value of the UDP Source Port of the corresponding signalling request message.

The UDP Source Port shall be the value from the UDP Destination Port of the corresponding signalling request message.

9.1.1.3 Encapsulated T-PDUs

The UDP Destination Port shall be the server port number 3386. It shall be reserved for GTP. The UDP Source Port is a locally allocated port number at the sending GSN.

9.1.2 IP Header

An Internet Protocol (IP) compliant with STD 0005 shall be used.

9.1.2.1 Signalling request messages and Encapsulated T-PDUs

The IP Source Address shall be an IP address of the source GSN from which the message is originating.

The IP Destination Address in a GTP signalling request message shall be an IP address of the destination GSN. The IP Destination Address in an encapsulated T-PDU GTP shall be an IP address of the destination GSN.

9.1.2.2 Signalling response messages

The IP Source Address shall be copied from the IP Destination Address of the corresponding signalling request message.

The IP Destination Address shall be copied from the IP Source Address of the GTP signalling request message to which this GSN is replying to.

9.2 TCP/IP

TCP/IP is the recommended choice as a reliable connection-oriented path to tunnel connection-oriented T-PDUs. A Transmission Control Protocol (TCP) compliant with STD 0007 shall be used.

9.2.1 TCP Header

The TCP Destination Port shall be the server port number 3386. This value shall be reserved for G-PDUs. Extra implementation specific destination ports are possible but all GSNs shall support the server port number 3386.

The TCP Source Port can be arbitrarily selected and is locally assigned at the sending GSN.

9.2.2 IP Header

The IP Source Address shall be an IP address of the source GSN from which the message is originating.

The IP Destination Address shall be an IP address of the destination GSN.