Overview; 3Gpp2 Standard Pre-Paid Billing Overview; Custom Pre-Paid Billing Overview - Cisco ASR 5000 Administration Manual

▀ Overview

Overview
The system supports pre-paid billing for subscriber accounts that use RADIUS Accounting.
The system supports two methods of implementing Pre-paid Billing Support; Standard 3GPP2 Pre-paid Billing and
Custom Pre-paid Billing. The 3GPP2 standard is the recommended implementation.

3GPP2 Standard Pre-paid Billing Overview

The prepaid packet data service allows a user to purchase access to the network in advance, based on either volume or
duration. When a user connects to a service, the Prepaid Client (PPC) contacts the Prepaid Server (PPS) and verifies that
the user has available credits for the service. When a user runs out of credits, service is terminated until the user
purchases additional credits.
The Prepaid Data Service implementation is compliant with 3GPP2 IS-835-C. This solution provides a standards based
implementation that can effectively interoperate with additional vendors equipment when required. The system
primarily uses the PPAC (PrePaid Accounting Capability) and PPAQ (PrePaid Accounting Quota) VSAs to implement
PrePaid service. The PPAC VSA is used to determine the capabilities of the PPC. When the PPC sends the PPAC VSA
it specifies if it supports duration, volume or both types of PrePaid service. When the PPS sends a PPAC VSA it
specifies the type of PrePaid service to use for the particular session. The PPAQ VSA specifies the characteristics of the
PrePaid accounting service. This includes quota & threshold values for both duration and volume PrePaid service.
Through the use of these VSAs, the PPC and PPS communicate the status of the session and when the user has run out
of quota, the service can be terminated.
The PrePaid Client resides on the system and communicates with the PPS through the use of RADIUS messages
exchanged with the RADIUS server.

Custom Pre-paid Billing Overview

In the Access-Accept from the RADIUS server the system receives attributes which indicate the number of byte credits
available for the subscriber. Byte throughput can be pre-paid for traffic inbound to the system, outbound from the
system, or an amount that combines both inbound and outbound traffic. Five attributes are used: one for traffic inbound
to the system, one for traffic outbound from the system, one that combines traffic in both directions, one that only
indicates that the user should be re-authenticated regardless of the byte counters, and one for the low watermark in
percent.
The low watermark value is multiplied by the number of byte credits granted in the Access-Accept to arrive at a
threshold. Once the number of byte credits remaining is lower than this number, a new Access-Request is issued. If the
Access-Request is issued because the Low Watermark has been reached, then a new Low Watermark is calculated from
the number of byte credits granted in the Access-Accept, but only if the number of byte credits granted is a non-zero
value. If the Access-Request is issued for any other reason, then the Low Watermark is not re-calculated.
The system re-authorizes an active subscriber that has used up its byte credits by issuing a RADIUS Access-Request to
the RADIUS server. A valid Access-Reject or a RADIUS timeout results in immediate disconnect of the subscriber
session. An Access-Accept without attributes that authorize more byte credits allows the subscriber session to continue
with the remaining credits. An Access-Accept with attributes containing byte credits results in the addition of these byte
credits to the subscriber session, and the continuation of the session until the subscriber session byte credits have been
reduced to the low watermark received in the access accept. If not received, it defaults to 10%.
The system continues to service the subscriber session while the RADIUS request for re-authorization is in process. If
the counter reaches zero before the response the subscriber session is terminated immediately.
▄ Cisco ASR 5000 IP Services Gateway Administration Guide
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Pre-paid Billing
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