Create PDP Context Request/ Response

GTP-C

Sent from an SGSN to a GGSN node as part of a GPRS PDP Context Activation procedure or the Network-Requested PDP Context Activation procedure. A valid request initiates the creation of a tunnel.

Update PDP Context Request/ Response

GTP-C

Used when PDP Context information changes, such as when a mobile device changes location.

Delete PDP Context Request/ Response

GTP-C

Used to terminate a PDP Context, and confirm the context has been deleted.

Create AA PDP Context Request/ Response

GTP-C

Sent as part of the GPRS Anonymous Access PDP Context Activation. It is used to create a tunnel between a context in the SGSN and a context in the GGSN.

Delete AA PDP Context Request/ Response

GTP-C

Sent as part of the GPRS PDP Anonymous Access Context Deactivation procedure to deactivate an activated PDP Context. It contains Cause and Private Extension Information Elements

Error Indication

GTP-U

Sent to the GGSN when a tunnel PDU is received for the following conditions:

— No PDP context exists

— PDP context is inactive

— No MM context exists

— GGSN deletes its PDP context when the message is received.

PDU Notification Request/ Response/ Reject Request/ Reject Response

GTP-C

When receiving a Tunneled PDU (T-PDU), the GGSN checks if a PDP context is established for the given PDP address. If no PDP context has been established, the GGSN may initiate the Network-requested PDP Context Activation procedure by sending a PDU Notification Request to the SGSN.

Reject Request - Sent when the PDP context requested by the GGSN cannot be established.