Cisco ASR 5000 Series Administration Manual page 110

▀ How This Configuration Works
1. If the DHCP client mode is used for the dynamic assignment of IP addresses for subscriber PDP contexts, the
system will retrieve addresses from the server over the DHCP interface during boot up and store them in cache
memory.
2. An IP packet data unit (PDU) is received by the GGSN from the PDN.
3. The GGSN determines if it is configured to support network-initiated sessions. If so, it begins the Network-
Requested PDP Context Activation procedure, otherwise it discards the packet.
4. The GGSN determines if the MS is reachable by communicating with the HLR through a MAP node over one of
the Gn interfaces.
5. The GGSN works with the SGSN to activate the MS.
6. Once activated, the MS initiates a PDP context resulting in the sending of a Create PDP Context Request
message from the SGSN to the GGSN service over the Gn interface. The message contains information such as
the PDP Type, APN, and charging characteristics.
7. The GGSN determines whether or not it is configured with an APN identical to the one specified in the message.
If so, it determines how to process the session based on the configuration of the APN.
8. If the MS requires a dynamically assigned address, the GGSN assigns one from those stored in its memory
cache.
9. The GGSN returns an affirmative Create PDP Context Response to the SGSN over the Gn interface.
10. The MS sends/receives data to/from the packet data network over the GGSN‟s PDN interface.
11. Upon termination of the subscriber session, the GGSN sends GGSN charging detail records to the CGF using
GTPP over the Ga interface.
▄ Cisco ASR 5000 Series Gateway GPRS Support Node Administration Guide
GGSN Configuration Example
OL-22944-02