19.3.3 CSS fault recovery procedures

29.0023GPPMobile Application Part (MAP) specificationRelease 17TS

19.3.3.1 General

For the CSS, periodic back-up of data to non-volatile memory is mandatory.

Serving node numbers that have been changed after the last back-up and before the restart of the CSS cannot be recovered by reload from the non-volatile memory. Therefore, a restoration procedure is triggered for each IMSI record that has been affected by the CSS fault at the first authenticated radio contact with the MS concerned.

The message flow for CSS restoration for a non-GPRS subscriber is shown in figure 19.3.3/1.

The message flow for CSS restoration for a GPRS subscriber is shown in figure 19.3.3/2.

1) MAP_RESET_req/ind

2) MAP_UPDATE_VCSG_LOCATION_req/ind

3) MAP_INSERT_SUBSCRIBER_DATA_req/ind

4) MAP_INSERT_SUBSCRIBER_DATA_rsp/cnf

5) MAP_UPDATE_VCSG_LOCATION_rsp/cnf

Figure 19.3.3/1: Message flow for CSS restoration (non-GPRS)

1) MAP_RESET_req/ind

2) MAP_UPDATE_VCSG_LOCATION_req/ind

3) MAP_INSERT_SUBSCRIBER_DATA_req/ind

4) MAP_INSERT_SUBSCRIBER_DATA_rsp/cnf

5) MAP_UPDATE_VCSG_LOCATION_rsp/cnf

Figure 19.3.3/2: Message flow for CSS restoration (GPRS)

19.3.3.2 Procedure in the CSS

The MAP process in the CSS to notify the relevant serving nodes that the CSS has restarted is shown in figure 19.3.3/3.

The SGSN address list includes one instance of the address of each SGSN in which (according to the CSS data retrieved from the non-volatile memory) there is at least one subscriber registered who is affected by the CSS restart.

The VLR address list includes one instance of the address of each VLR in which (according to the CSS data retrieved from the non-volatile memory) there is at least one subscriber registered who is affected by the CSS restart.

The MAP process in the CSS to notify a VLR that the CSS has restarted is shown in figure 19.3.3/4. The MAP process invokes a macro not defined in this clause; the definition of this macro can be found as follows:

Receive_Open_Cnf see clause 25.1.2.

The MAP process in the CSS to notify an SGSN that the CSS has restarted is shown in figure 19.3.3/5. The MAP process invokes a macro not defined in this clause; the definition of this macro can be found as follows:

Receive_Open_Cnf see clause 25.1.2.

19.3.3.3 Procedure in the VLR

The MAP process in the VLR to handle a notification that a CSS has restarted is shown in figure 19.3.3/6. The MAP process invokes a macro not defined in this clause; the definition of this macro can be found as follows:

Receive_Open_Ind see clause 25.1.1.

The VLR uses the CSS number (filled in Sending Node number parameter) included in the MAP_RESET indication to identify the user’s IMSI records which are affected by the CSS restart.

19.3.3.4 Procedure in the SGSN

The MAP process in the SGSN to handle a notification that a CSS has restarted is shown in figure 19.3.3/6. The MAP process invokes a macro not defined in this clause; the definition of this macro can be found as follows:

Receive_Open_Ind see clause 25.1.1.

The SGSN uses the CSS number (filled in Sending Node number parameter) included in the MAP_RESET indication to identify the user’s IMSI records which are affected by the CSS restart.

Figure 19.3.3/3: Process Restart_CSS

Figure 19.3.3/4: Process Send_Reset_To_VLR_CSS

Figure 19.3.3/5: Process Send_Reset_To_SGSN_CSS

Figure 19.3.3/6: Process Receive_Reset_From_CSS_VLR

Figure 19.3.3/7: Process Receive_Reset_From_CSS_SGSN