Aaa Server Groups; Dynamic Policy And Charging: Gxa Reference Interface - Cisco ASR 5000 Series Administration Manual

HRPD Serving Gateway Overview
platforms. The systems use the Charging Trigger Function (CTF) to transfer offline accounting records via a Diameter
interface to an adjunct Charging Data Function (CDF) / Charging Gateway Function (CGF). The HSGW and Serving
Gateway collect charging information for each mobile subscriber UE pertaining to the radio network usage while the P-
GW collects charging information for each mobile subscriber related to the external data network usage.
The ASR 5000 Charging Trigger Function features dual redundant 140GB RAID hard drives and up to 100GB of
capacity on each drive is reserved for writing charging records (CDRs, UDRs, and FDRs) to local file directories with
non-volatile persistent memory. The CTF periodically uses the sFTP protocol to push charging files to the CDF/CGF. It
is also possible for the CDF/CGF to pull offline accounting records at various intervals or times of the day.
The HSGW, SGW and PGW collect information per-user, per IP CAN bearer or per service. Bearer charging is used to
collect charging information related to data volumes sent to and received from the UE and categorized by QoS traffic
class. Users can be identified by MSISDN or IMSI. Flow Data Records (FDRs) are used to correlate application
charging data with EPC bearer usage information. The FDRs contain application level charging information like service
identifiers, rating groups, IMS charging identifiers that can be used to identify the application. The FDRs also contain
the authorized QoS information (QCI) that was assigned to a given flow. This information is used correlate charging
records with EPC bearers.

AAA Server Groups

Value-added feature to enable VPN service provisioning for enterprise or MVNO customers. Enables each corporate
customer to maintain its own AAA servers with its own unique configurable parameters and custom dictionaries.
This feature provides support for up to 800 AAA server groups and 800 NAS IP addresses that can be provisioned
within a single context or across the entire chassis. A total of 128 servers can be assigned to an individual server group.
Up to 1,600 accounting, authentication and/or mediation servers are supported per chassis.
Important:
(PSCs).

Dynamic Policy and Charging: Gxa Reference Interface

Enables network initiated policy based usage controls for such functions as service data flow authorization for EPS
bearers, QCI mapping, modified QoS treatments and per-APN AMBR bandwidth rate enforcement.
As referenced in Figure 1 below, in an e-HRPD application the Gxa reference point is defined to transfer QoS policy
information between the PCRF and Bearer Binding Event Reporting Function (BBERF) on the HSGW. In contrast with
an S5/S8 GTP network model where the sole policy enforcement point resides on the PGW, the S2a model introduces
the additional BBERF function to map EPS bearers to the main and auxiliary A10 connections. Gxa is sometimes
referred to as an off-path signaling interface because no in-band procedure is defined to convey PCC rules via the
PMIPv6 S2a reference interface. Gxa is a Diameter based policy signaling interface.
Gxa signaling is used for bearer binding and reporting of events. It provides control over the user plane traffic handling
and encompasses the following functionality:
Provisioning, update and removal of QoS rules from PCRF to BBERF.
Bearer binding: Associates Policy Charging and Control (PCC) rules with default or dedicated EPS bearers. For
a service data flow that is under QoS control, the Bearer Binding Function (BBF) within the HSGW ensures
that the service data flow is carried over the bearer with the appropriate QoS service class.
OL-22984-01
Due to additional memory requirements, this service can only be used with 8GB Packet Service Cards
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