Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
▀ How the SGSN Works
▄ SGSN Administration Guide, StarOS Release 18
MS-Initiated Detach Procedure
This process is initiated by the MS/UE for a range of reasons and results in the MS/UE becoming inactive as far as the
network is concerned.
network is concerned.
Figure 12. MS-Initiated Combined GPRS/IMSI Detach
The following table provides details for the activity involved in each step noted in the diagram above.
Table 5. MS-Initiated Combined GPRS/IMSI Detach Procedure
Step
Description
1
The UE sends a Detach Request message to the SGSN containing the Detach Type, P-TMSI, P-TMSI Signature, and
Switch off indicator (i.e. if UE is detaching because of a power off).
Switch off indicator (i.e. if UE is detaching because of a power off).
2
The SGSN sends Delete PDP Context Request message to the GGSN containing the TEID.
The GGSN sends a Delete PDP Context Response back to the SGSN.
The SGSN stops generating S-CDR info at the end of the PDP context.
The GGSN sends a Delete PDP Context Response back to the SGSN.
The SGSN stops generating S-CDR info at the end of the PDP context.
3
The SGSN sends a IMSI Detach Indication message to the MSC/VLR.
4
The SGSN sends a GPRS Detach Indication message to the MSC/VLR.
The SGSN stops generating M-CDR upon GPRS Detach.
The SGSN stops generating M-CDR upon GPRS Detach.
5
If the detach is not due to a UE switch off, the SGSN sends a Detach Accept message to the UE.
6
Since the UE GPRS Detached, the SGSN releases the Packet Switched Signaling Connection.