Network-Initiated Session Call Flow - Cisco ASR 5000 Series Administration Manual

▀ How GGSN Works
14. The GGSN delivers the GGSN Charging Detail Records (G-CDRs) to a Charging Gateway (CG) using GTP
Prime (GTPP). Note that, though not shown in this example, the GGSN could optionally be configured to send
partial CDRs while the PDP context is active.
15. For each accounting message received from the GGSN, the CG responds with an acknowledgement.

Network-Initiated Session Call Flow

The following figure and the text that follows describe the call flow for a successful network-initiated data session.
Figure 12. Network-initiated Session Call Flow
1. An IP Packet Data Unit (PDU) is received by the GGSN from the PDN. The GGSN determines if it is configured
to support network-initiated sessions. If not, it will discard the packet. If so, it will begin the Network-
Requested PDP Context Activation procedure.
2. The GGSN may issue a Send Routing Information for GPRS request to the HLR to determine if the MS is
reachable. The message includes the MS‟s International Mobile Subscriber Identity (IMSI).
▄ Cisco ASR 5000 Series Gateway GPRS Support Node Administration Guide
GGSN Support in GPRS/UMTS Wireless Data Services
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