Gx Interface Support
▀ Rel. 6 Gx Interface
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
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Rel. 6 Gx Interface
Rel. 6 Gx interface support is available on the Cisco ASR chassis running StarOS 8.0 and later releases for the
following products:
GGSN
IPSG
Important:
In 14.0 and later releases, Rel. 6 Gx interface functionality is not supported on the chassis.
This section describes the following topics:
Introduction
How it Works
Configuring Rel. 6 Gx Interface
Introduction
In GPRS/UMTS networks, the client functionality lies with the GGSN/IPSG, therefore in the IMS authorization
scenario it is also called Access Gateway (AGW).
The provisioning of charging rules that are based on the dynamic analysis of flows used for the IMS session is carried
out over the Gx interface. In 3GPP, Rel. 6 the Gx is an interface between Access Gateway functioning as Traffic Plane
Function (TPF) and the Charging Rule Function (CRF). It is based on the Diameter Base Protocol (DIABASE) and the
Diameter Credit Control Application (DCCA) standard. The GGSN/TPF acts as the client where as the CRF contains
the Diameter server functionality.
The AGW is required to perform query, in reply to which the servers provision certain policy or rules that are enforced
at the AGW for that particular subscriber session. The CRF analyzes the IP flow data, which in turn has been retrieved
from the Session Description Protocol (SDP) data exchanged during IMS session establishment.
Important:
In addition to standard Gx interface functionality, the Gx interface implemented here provides
support of SBLP with additional AVPs in custom DPCA dictionaries. For more information on customer-specific
support contact your Cisco account representative. In view of required flow bandwidth and QoS, the system provides
enhanced support for use of Service Based Local Policy (SBLP) to provision and control the resources used by the IMS
subscriber. SBLP is based on the dynamic parameters such as the media/traffic flows for data transport, network
conditions and static parameters, such as subscriber configuration and category. It also provides Flow-based Charging
(FBC) mechanism to charge the subscriber dynamically based on content usage. With this additional functionality, the
Cisco Systems Gateway can act as an Enhanced Policy Decision Function (E-PDF).
Supported Networks and Platforms
This feature is supported on all chassis with StarOS Release 8.0 or later running GGSN service for the core network
services.
