GPRS tunnelling protocol (GTP)

GPRS tunnelling agreement is the defining IP-based agreement of the GPRS amount network. Primarily it is the agreement which allows end users of a GSM or WCDMA arrangement to move from abode to abode while continuing to affix to the Internet as if from one area at the Gateway GPRS Support Node (GGSN). It does this by accustomed the subscriber's abstracts from the subscriber's accepted Serving GPRS Support Node (SGSN) to the GGSN which is administration the subscriber's session. Three forms of GTP are acclimated by the GPRS amount network.

GTP-U

for alteration of user abstracts in afar tunnels for anniversary Packet Abstracts Agreement (PDP) context

GTP-C

for ascendancy affidavit including:

bureaucracy and abatement of PDP contexts

analysis of GSN reachability

updates; e.g., as subscribers move from one SGSN to another.

GTP'

for alteration of charging abstracts from GSNs to the charging function.

GGSNs and SGSNs (collectively accepted as GSNs) accept for GTP-C letters on UDP anchorage 2123 and for GTP-U letters on anchorage 2152. This advice is absolute aural a individual network, or in the case of all-embracing roaming, via a GPRS adrift barter (GRX).

The Charging Gateway Action (CGF) listens to GTP' letters beatific from the GSNs on TCP or UDP anchorage 3386. The amount arrangement sends charging advice to the CGF, about including PDP ambience activation times and the abundance of abstracts which the end user has transferred. However, this advice which occurs aural one arrangement is beneath connected and may, depending on the bell-ringer and agreement options, use proprietary encoding or even an absolutely proprietary system.

GTP adaptation aught supports both signalling and user abstracts beneath one all-encompassing header. It can be acclimated with UDP (User Datagram Protocol) or TCP (Transmission Ascendancy Protocol) on the registered anchorage 3386. GTP adaptation one is acclimated alone on UDP. The ascendancy even agreement GTP-C (Control) application registered anchorage 2123 and the user even agreement GTP-U (User) application registered anchorage 2152.