Cisco ASR 5000 Series, Обзор продукта

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Serving GPRS Support Node (SGSN) Overview
▀ How the SGSN Works
▄ Cisco ASR 5000 Series Product Overview
OL-22938-02
Network-Initiated PDP Context Activation Process
In some cases, the GGSN receives information that requires it to request the MS/UE to activate a PDP context. The
network, or the GGSN in this case, is not actually initiating the PDP context activation -- it is requesting the MS/UE to
activate the PDP context in the following procedure:
Figure 171. Network-Initiated PDP Context Activation
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MS/UE SGSN GGSN HLR
The table below provides details describing the steps indicated in the graphic above.
Table 89. Network Invites MS/UE to Activate PDP Context
Step Description
1 The GGSN receives a PDU with a static PDP address that the GGSN ‗knows‘ is for an MS/UE in its PLMN.
2 The GGSN uses the IMSI in place of the PDP address and sends an SRI (send routing information for GPRS) to the HLR.
The HLR sends an SRI response back to the GGSN. The response may include the access of the target SGSN and it may
also indicate it the MS/UE is not reachable, in which case it will include the reason in the response message.
3 The GGSN sends a PDU Notification Request to the SGSN (if the address was received). If the address was not received or
if the MS/UE continues to be unreachable, the GGSN sets a flag marking that the MS/UE was unreachable.
The notified SGSN sends a PDU Notification Response to the GGSN.