Cisco ASR 5000 Series Administration Manual page 68

▀ How GGSN Works
Figure 14. Virtual Dialup Access Call Flow
1. The Mobile Station (MS) goes through the process of attaching itself to the GPRS/UMTS network.
2. The MS sends an Activate PDP Context Request message that is received by an SGSN. The message contains
information about the subscriber such as the Network layer Service Access Point Identifier (NSAPI), PDP
Type, PDP Address, Access Point Name (APN), Quality of Service (QoS) requested, and PDP configuration
options.
3. The SGSN authenticates the request message and sends a Create PDP Context Request message to a GGSN
using the GPRS Tunneling Protocol (GTPC, "C" indicates the control signaling aspect of the protocol). The
▄ Cisco ASR 5000 Series Gateway GPRS Support Node Administration Guide
GGSN Support in GPRS/UMTS Wireless Data Services
OL-22944-02