Message Type | Used by | Description |
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. |