Cisco ASR 5000 Series Administration Manual page 122

▀ Example 1: Mobile IP Support Using the System as a GGSN/FA
Figure 26. Call Processing When Using the system as a GGSN/FA
BSS/UTRAN
Context (Ctx.)
Interface
Service or
Configuration (Cfg.)
1. A Create PDP Context Request message for a subscriber session is sent from the SGSN to the GGSN service
over the Gn interface. The message contains information such as the PDP Type, APN, and charging
characteristics.
2. 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. In this case, it is
determined that Mobile IP must be used. From the APM configuration, the system also determines the context
in which the FA service is configured.
3. If subscriber authentication is required, the GGSN authenticates the subscriber by communicating with a
RADIUS server over the AAA interface.
4. The GGSN returns an affirmative Create PDP Context Response to the SGSN over the Gn interface. The home
address assigned to the mobile as part of the response is 0.0.0.0 indicating that it will be reset with a Home
address after the PDP context activation procedure.
5. The FA component of the GGSN sends a Agent Advertisement message to the MS. The message contains the
FA parameters needed by the mobile such as one or more card-of addresses. The message is sent as an IP
limited broadcast message (i.e. destination address 255.255.255.255), however only on the requesting MS‟s
TEID to avoid broadcast over the radio interface.
▄ Cisco ASR 5000 Series Gateway GPRS Support Node Administration Guide
CGF
11
1 6
4 5 9
SGSN
GGSN/FA
Source Ctx.
G
GTPP
a
Cfg.
2
G
GGSN-
n
Service
8
Optional
Foreign
AAA Server
3
7
Packet Data Network
10
AAA Ctx.
A
Auth.
A
Cfg.
A
APN
Cfg.
FA-
Gi
Service
MIP Dest.
Ctx.
Gi
Dest.
Ctx.
Mobile IP Configuration Examples
Home
AAA Server
HA
OL-22944-02