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

The optional Location Management messages are defined to support the case when Network-Requested PDP Context Activation procedures are used and a GGSN does not have a SS7 MAP interface, i.e. a Gc interface. GTP is then used to transfer signalling messages between the GGSN and a GTP-MAP protocol-converting GSN in the GPRS backbone network. The GTP-MAP protocol-converting GSN converts the signalling messages described in this section between GTP and MAP. The MAP messages are sent to and received from the HLR. The GTP-MAP protocol-converting function is described in GSM 03.60. The MAP protocol describing the corresponding procedures and messages is described in GSM 09.02. This alternative method is illustrated in Figure 6.

Figure 6: GGSN – HLR Signalling via a GTP-MAP protocol-converter in a GSN

When receiving a T-PDU the GGSN checks if a PDP Context is established for that PDP address. If no PDP context has been previously established the GGSN may store the T-PDU, try to initiate the Network-Requested PDP Context Activation procedure and, when the activation procedure is completed, deliver the T-PDU.

To support Network-Requested PDP Context Activation the GGSN has to have static PDP information about the PDP address.

7.6.1 Send Routeing Information for GPRS Request

The GGSN may send a Send Routeing Information for GPRS Request message to a GTP-MAP protocol-converting GSN, to obtain the IP address of the SGSN where the MS is located, when no PDP context is established.

The IMSI information element contains the IMSI to be used as a key to get the IP address of the SGSN.

If the GGSN receives a Create PDP Context Request after a Send Routeing Information for GPRS Request has been sent but before a Send Routeing Information for GPRS Response has been received, the GGSN shall handle the Create PDP Context Request as a normal context activation and ignore the following Send Routeing Information for GPRS Response.

The optional Private Extension contains vendor or operator specific information.

Table 19: Information elements in a Send Routeing Information for GPRS Request

7.6.2 Send Routeing Information for GPRS Response

The GTP-MAP protocol-converting GSN sends a Send Routeing Information for GPRS Response message as a response to the Send Routeing Information for GPRS Request message to the GGSN that sent the request.

The Cause value indicates if the GTP-MAP protocol-converting GSN accepted the request or not.

Possible Cause values are:

– ‘Request Accepted’

– ‘No resources available’

– ‘Service not supported’

– ‘System failure’

– ‘Mandatory IE incorrect’

– ‘Mandatory IE missing’

– ‘Optional IE incorrect’

– ‘Invalid message format’

– ‘Version not supported’.

The MAP Cause information element contains the MAP error code received from the HLR and shall not be included if the Cause contains another value than ‘Request accepted’.

The GSN Address information element contains the IP address of the SGSN and shall not be included if the Cause contains another value than ‘Request accepted’.

It is an implementation issue what to do if the Cause or MAP Cause indicates that no location information is available.

The MS not Reachable Reason information element indicates the reason for the setting of the MNRG flag and shall not be included if the Cause contains another value than ‘Request accepted’.

The optional Private Extension contains vendor or operator specific information.

Table 20: Information elements in a Send Routeing Information for GPRS Response

7.6.3 Failure Report Request

The GGSN may send this message to the GTP-MAP protocol-converting GSN to set the MNRG flag for the IMSI in the HLR.

The IMSI information element contains the IMSI for which the MNRG shall be set.

The optional Private Extension contains vendor or operator specific information.

Table 21: Information elements in a Failure Report Request

7.6.4 Failure Report Response

The GTP-MAP protocol-converting GSN sends a Failure Report Response message as a response to the Failure Report Request message to the GGSN that sent the request.

The Cause value indicates if the GTP-MAP protocol-converting GSN accepted the request or not.

Possible Cause values are:

– ‘Request Accepted’

– ‘No resources available’

– ‘Service not supported’

– ‘System failure’

– ‘Mandatory IE incorrect’

– ‘Mandatory IE missing’

– ‘Optional IE incorrect’

– ‘Invalid message format’

– ‘Version not supported’.

The MAP Cause information element contains the MAP error code received from the HLR and shall not be included if the Cause contains another value than ‘Request accepted’

It is an implementation issue what to do if the Cause or MAP Cause indicates that the HLR has not received the request or rejected the request.

The optional Private Extension contains vendor or operator specific information.

Table 22: Information elements in a Failure Report Response

7.6.5 Note MS GPRS Present Request

The GTP-MAP protocol-converting GSN sends a Note MS GPRS Present message to notify that an MS should be reachable for GPRS again.

The GGSN shall use the IMSI in the request and find all PDP contexts for the IMSI. The MNRG shall be cleared and the SGSN IP address from the request shall be stored in each found PDP context.

The IMSI information element contains the IMSI for the PDP contexts.

The GSN Address information element contains the IP address of the SGSN.

The optional Private Extension contains vendor or operator specific information.

Table 23: Information elements in a Note MS Present Request

7.6.6 Note MS GPRS Present Response

The GGSN sends a Note MS GPRS Present Response message to the GTP-MAP protocol-converting GSN as a response to the Note MS GPRS Present Request.

Possible Cause values are:

– ‘Request Accepted’

– ‘Mandatory IE incorrect’

– ‘Mandatory IE missing’

– ‘Optional IE incorrect’

– ‘Invalid message format’.

The optional Private Extension contains vendor or operator specific information.

Table 24: Information elements in a Note MS Present Response