Rf Interface Support
▀ Features and Terminology
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
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Features and Terminology
This section describes features and terminology pertaining to Rf functionality.
Offline Charging Scenarios
Offline charging for both events and sessions between CTF and the CDF is performed using the Rf reference point as
defined in 3GPP TS 32.240.
Basic Principles
The Diameter client and server must implement the basic functionality of Diameter accounting, as defined by the RFC
3588 — Diameter Base Protocol.
For offline charging, the CTF implements the accounting state machine as described in RFC 3588. The CDF server
implements the accounting state machine "SERVER, STATELESS ACCOUNTING" as specified in RFC 3588, i.e.
there is no order in which the server expects to receive the accounting information.
The reporting of offline charging events to the CDF is managed through the Diameter Accounting Request (ACR)
message. Rf supports the following ACR event types:
Table 37.
Rf ACR Event Types
Request
Description
START
Starts an accounting session
INTERIM Updates an accounting session
STOP
Stops an accounting session
EVENT
Indicates a one-time accounting event
ACR types START, INTERIM and STOP are used for accounting data related to successful sessions. In contrast,
EVENT accounting data is unrelated to sessions, and is used e.g. for a simple registration or interrogation and successful
service event triggered by a network element. In addition, EVENT accounting data is also used for unsuccessful session
establishment attempts.
Important:
The ACR Event Type "EVENT" is supported in Rf CDRs only in the case of IMS specific Rf
implementation.
The following table describes all possible ACRs that might be sent from the IMS nodes i.e. a P-CSCF and S-CSCF.
Table 38.
Accounting Request Messages Triggered by SIP Methods or ISUP Messages for P-CSCF and S-CSCF
Diameter Message Triggering SIP Method/ISUP Message
ACR [Start]
SIP 200 OK acknowledging an initial SIP INVITE
