PDP Context
3.6 PDP Context
A PDP context specifies access to an external packet-switching network. The data associated with the PDP context contains information such as the type of packet-switching network, the MS PDP address that is the IP address, the reference of GGSN, and the requested QoS. A PDP context is handled by the MS, SGSN, and GGSN and is identified by a mobile's PDP address within these entities. Several PDP contexts can be activated at the same time within a given MS.
A PDP context activation procedure is used to create a PDP context. This procedure may be initiated either by the MS or by the network. The MS is always GPRS-attached before PDP context negotiation. The PDP context activation may be performed:
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Automatically, if it is generated during a given procedure to perform a GPRS data transfer;
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Manually, if it is generated by user intervention.
A PDP context deactivation procedure is used to remove a PDP context. This procedure may be initiated either by the MS or by the network (SGSN or GGSN). The PDP context deactivation may be generated either during an application deactivation or during the GPRS detach or delete subscriber data procedures.
A PDP context modification procedure is used to modify the PDP context. This procedure may be initiated either by the MS or by the network in order to change QoS parameters or traffic flow template (TFT) parameters.
All PDP context procedures are handled by the SM protocol between the MS and the SGSN and by the GTP between the SGSN and the GGSN.
