1. Rc (TS 132.296) and Sy (TS 29.219) Interface
Session #2
Author: Victor I. Fajardo
Date: Sept. 27, 2013
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2. Agenda Overview of the OCS (On-line Charging system)
Online vs. Offline charging
Functional requirements
Service consumption rating
Account balance management
Charging transaction control
Charge support
Correlation function
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3. Agenda The Sy Interface The Rc Interface Policy Enforcement Overview
Spending Limit report (Request, Notification and Cancelation)
Protocol Details
Message Formats
Message Flows
The Rc Interface
Account Balance Management Overview
Debit operation
Account reservation
Refund
Balance Query
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4. OCS Overview (Architecture)
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5. Online vs. Off-line Charging
Offline charging is applied to users who pay for their services periodically (e.g., at the end of the month)
Online charging (credit-based charging) is used for prepaid services
Real-time credit control
Both real-time and prepaid maybe applied to the same session
Charging function addresses
Addresses distributed to each IMS entities and provide a common location for each entity to send charging information
Charging Data Function (CDF) addresses are used for offline billing and Online Charging Function (OCF) for online billing.
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6. Offline Charging
SIP network entities (P-CSCF, I-CSCF, S-CSCF, BGCF, MRFC, MGCF, AS) involved in the session uses Rf to send accounting information to a CDF
CDF will collect all this information, and build a Call Detail Record (CDR), which is sent to the billing system (BS) of the domain
Each session carries an IMS Charging Identifier (ICID) as a unique identifier generated by the first IMS entity involved in a SIP transaction and used for the correlation with CDRs
Each domain has its own charging network
Billing systems in different domains will also exchange information, so that roaming can be applied
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7. Online Charging
The S-CSCF talks to a Session Charging Function (SCF) which looks like a regular SIP application server
The SCF can signal the S-CSCF to terminate the session when the user runs out of credits during a session
The AS (Application Server) use the Ro interface to the Online charging function
Immediate Event Charging (IEC)
The number of credit units is immediately deducted from the user's account
AS is then authorized to provide the service.
The service is not authorized when not enough credit units are available
Charging with Unit Reservation (ECUR)
The number of credit units in the user's account is reserved.
AS is then authorizes
After the service is over, the number of spent credit units is reported and deducted from the account; the reserved credit units are then cleared
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8. OCS Functions Event Based Charging Function
On the bearer level
It controls the bearer usage in the network, e.g. SMS
On the subsystem level
It controls the resource availability in network, e.g. it has the ability to grant or deny the resource usage
On the service level
it has the ability to grant or deny the service usage in the network
Session Based Charging Function
It controls the bearer usage in the network, e.g. in terms of time or volume granted
Grant or deny a session setup request and to terminate an existing session
It controls service availability in the network, e.g. it has the ability to grant or deny a usage of a service
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9. OCS Rating Functions
Rating for network- and external services and applications (session, service, event) before and after service delivery;
Cross-product and cross-channel discounts, benefits and allowances.
The Rating Function must be able to handle a wide variety of rateable instances, such as:
Rating of volume (in terms of granted units or money, e.g. based on charging initiated by an access network entity);
Rating of time (in terms of granted units or money, e.g. based on charging initiated by a SIP application);
Rating of events (e.g. based on charging of web content or MMS)
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10. The Sy Interface
The Sy reference point is located between the Policy and Charging Rules Function (PCRF) and the OCS
Enables transfer of policy counter status information relating to subscriber spending from OCS to PCRF
Request of policy counter status reporting from PCRF to OCS and subscribe to or unsubscribe from spending limit reports (i.e. notifications of policy counter status changes).
Notification of spending limit reports from OCS to PCRF.
Cancellation of spending limit reporting from PCRF to OCS
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11. Diameter Session #2

12. Sy Spending Limit Request and Answer Commands
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13. Sy Spending Status Notification Request and Answer Commands
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14. Sy Specific Diameter AVPs
Description
Policy-Counter-Identifier
Uniquely identifies a policy counter that is maintained per subscriber within the OCS
Policy-Counter-Status
Identifies the policy counter status applicable for a specific policy counter and subscriber
Policy-Counter-Status-Report
Report the status of a specific policy counter
SL-Request-Type
Informs the OCS whether the SLR command is being sent as part of the initial or intermediate spending limit report request procedure
Pending-Policy-Counter-Information
Contains the pending policy counter status and the active time
Pending-Policy-Counter-Change-Time
Indicates the NTP time at which the pending policy counter becomes the current status of a policy counter
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15. Sy Initial/Intermediate Report Message Flows
H-PCRF
OCS
1. Policy decision depends on spending info
2. Diameter SLR
3. Diameter SLA
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16. Sy Initial/Intermediate Reports Request AVPs
Element
Diameter AVP
Description
User Identity
Subscription-Id
Contain the identity of the user. It shall be present in the initial request when the SL-Request-Type=INITIAL_REQUEST
Request Type
SL-Request-Type
Indicate whether this is the initial or a subsequent request for the user
Subscribed Policy Counter Identifier List
Policy-Counter- Identifier
Indicate the list of policy counter identifiers to be subscribed to. In the intermediate spending limit report request procedure, this list overrides a previously provisioned list. If omitted in either the Initial or Intermediate Spending Limit Report Request procedures the PCRF requests subscription to all available policy counters.
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17. Sy Initial/Intermediate Reports Response AVPs
Element
Diameter AVP
Description
Policy Counter Status Report
Policy-Counter- Status-Report
If present, this information element shall contain a policy counter identifier, the current status value and/or pending policy counter statuses with the activation times
Result
Result-Code
Contain the result of the operation
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18. Sy Intermediate Spending Limit Report Message Flows
H-PCRF
OCS
1. Additional or fewer policy counters are determined to be relevant for policy decision
2. Diameter SLR
3. Diameter SLA
4. Policy decision depends on spending info
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19. Sy Spending Limit Report Request
Element
Diameter AVP
Description
Policy Counter Status Report
Policy-Counter- Status-Report
If present, this information element shall contain a policy counter identifier, the current status value and/or pending policy counter statuses with the activation times
Sy Spending Limit Report Response
Element
Diameter AVP
Description
Result
Result-Code
Contain the result of the operation
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20. Sy Final Spending Limit Report Message Flows
H-PCRF
OCS
1. Decision to unsubscribe to changes in the Policy-Counter-Status
2. Diameter STR
3. Diameter STA
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21. Sy Spending Limit Report (Status Change) Message Flows
H-PCRF
OCS
1. Policy-Counter-Status change (e.g. Threshold reached)
2. Diameter SNR
3. Diameter SNA
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22. Sy Final Spending Limit Report Request
Element
Diameter AVP
Description
Termination Cause
Termination- Cause
This IE shall contain the reason why the session was terminated. It shall be set to "DIAMETER_LOGOUT”
Sy Final Spending Limit Report Response
Element
Diameter AVP
Description
Result
Result-Code
Contain the result of the operation
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23. The Rc Interface
The Rc reference point is located between the OCF (Online Charging Function) and ABMF (Account Balance Management Function)
ABMF manages subscribers credits
Supports query, credit, debit, refunds etc.
Rc allows the OCS to perform:
Immediate account debit operation
Event based account reservation debit/release operation
Session based account reservation debit/release operation
Account refund
Account balance query
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24. Rc Credit-Control Request and Answer Commands
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25. Rc Event Description Event Description Immediate Account Debit
The credit control process for events is controlled by the Credit- Control-Request (CCR) with corresponding CC-Requested-Type EVENT_REQUEST
Event based Account Debit with Reservation
Event Charging with Unit Reservation is used for credit control sessions and uses the Credit-Control-Request (CCR) with CC- Request-Type INITIAL and TERMINATION_REQUEST
Session based Account Debit with Reservation
Session Charging with Unit Reservation is used for credit control sessions and uses the Credit-Control-Request (CCR) with CC- Request-Type INITIAL / UPDATE and TERMINATION_REQUEST
Account Refund
Credit-Control-Request (CCR) with CC-Request-Type AVP set to EVENT_REQUEST to refund monetary units to the subscriber"s account. The Requested-Action AVP (RA) is set to REFUND_ACCOUNT
Account Balance
Query
Credit-Control-Request (CCR) with CC-Request-Type AVP set to EVENT_REQUEST to query the subscriber"s account. The Requested-Action AVP (RA) is set to BALANCE_CHECK
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26. Rc Specific Diameter AVPs
Description
AB-Response
Contains information related to present information and counters information which stored in the ABMF
Acct-Balance
Contains information related to return specific account balance when a subscriber has multiple accounts. A subscriber may have multiple accounts assigned by operator, e.g. normal account, present account, etc.
Acct-Balance-Id
Uniquely identifies the account balance within the ABMF
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27. Rc Immediate Account Debit Message Flows
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28. Rc Event based Account Reservation with Debit or Release Message Flows
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29. Rc Session based Account Reservation with Debit or Release Message Flows
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30. Rc Account Refund Message Flows
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31. Rc Balance Message Flows
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32. Questions ?
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