Edip Demirbilek, 27.01 - Technische Universität …€¦ · PPAC: Prepaid Accounting ... Assign...
Transcript of Edip Demirbilek, 27.01 - Technische Universität …€¦ · PPAC: Prepaid Accounting ... Assign...
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Prepaid Extensions for AAA Services
Edip Demirbilek, 27.01.2011
Motivation
Enterprise Networks Case: EDUROAM Purpose: Authentication, Authorization and Accounting (AAA Model) Standart Protocol: RADIUS
New Demand: Prepaid Capabilities Case: Wireless Networks in Airports Problem: Introducing a new Protocol is an Expensive Task
Ideal Solution: Use Existing Infrastructure with Add On’s Ideal Solution: Use Existing Infrastructure with Add-On’s Seminar Topic: Prepaid Extensions for Radius
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Overview
AAA Model Radius ProtocolRadius Protocol Prepaid System Prepaid Extensions for Radiusp
• Features and Example Flows
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AAA Model
Following questions serve the basic functionality of AAA.Who are you?Who are you?What services am I allowed to give you?What did you do with my services while you were using them?y y y g
AAA: Authentication, Authorization, Accounting
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Overview
AAA Model Radius ProtocolRadius Protocol Prepaid System Prepaid Extensions for Radiusp
• Features and Example Flows
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Radius in Network
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Properties of RADIUS
UDP-based connectionless protocol Supports the authentication-authorization-accounting modelSupports the authentication authorization accounting model Uses a hop-by-hop security model Supported Authentication Methodspp
• Password Authentication Protocol ( PAP) • Challenge-Handshake Authentication Protocol (CHAP) • Extensible Authentication Protocol (EAP)• Extensible Authentication Protocol (EAP)
Provides over 50 attribute/value pairs with the ability to create vendor-specific pairsp p
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A Radius Session
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Radius Data Packet Format
Data DescriptionCode 8-bit request/reply type:
1 A R t1 = Access-Request2 = Access-Accept3 = Access-Reject4 = Accounting Request4 = Accounting-Request5 = Accounting-Response11 = Access-Challenge
Id 8 bi bId 8-bit message sequence numberLength 16-bit message lengthAuthenticator 16 octet binary vectorAuthenticator 16 octet binary vectorAttributes Arbitrary numbers of information pairs
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Attribute-Value Pair Format
Data DescriptionAttribute 8-bit value-pair code, listed in the
di ti fildictionary fileLength 8-bit integer from 2-255.Value 0 - 253 octet information item.Value 0 253 octet information item.
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Overview
AAA Model Radius ProtocolRadius Protocol Prepaid System Prepaid Extensions for Radiusp
• Features and Example Flows
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Prepaid Service
Mobile subscribers count over the years in OECD countries 96.1 mobile subscribers per 100 inhabitants in 200796.1 mobile subscribers per 100 inhabitants in 2007 Italy had the highest penetration rate with 151 subscribers per
100 inhabitant.
1 200
Mobile (Postpaid) Mobile (prepaid) Mobile (3G)Mobile subscribers (millions)
8001 000
200400600
0200
1997 1999 2001 2003 2005 2007
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Prepaid Service
Today, 72 percent of the worlds 4.6 billion mobile subscribers March 2010use pre-paid services
28% Prepaid
72%
Prepaid
Postpaid
Charging ModelsVolume-based charging (e.g., 2 Cents/KiloByte).g g ( g , y )Duration-based charging (e.g., 3 Cents/minute).Resource-based charging (e.g., 3 videos for 1 Euros)g g ( g )Event-based charging (e.g., 7 Cents/ring tone or SMS or MMS).
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Charging Network Complexity
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Overview
AAA Model Radius ProtocolRadius Protocol Prepaid System Prepaid Extensions for Radiusp
• Features and Example Flows
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Prepaid Extension to Radius Service
First draft of Prepaid extensions for Radius protocol released in August 2003.
Current draft with number 18 which has been released at the end of October 2010.
Enable service providers to perform accounting and charging in real time• Make sure subscriber has sufficient credit before consuming the serviceMake sure subscriber has sufficient credit before consuming the service• Make sure service delivery interrupted when subscriber credit exhausted
Does not address prepaid service subscription or billing
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Architectural Model
End User initiates the connection with the Service Access Device to get Service.
Prepaid Client (PPC) in Service Access Device establish the connection with an AAA Server.
PPC meters the consumption of the service cooperating with Prepaid Server (PPS).
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Supported Features
Services and Quotas
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Simple Flow Duration-basedVolume-based
[allocates 5MB quota]
[allocates another 7MB]
PPAC: Prepaid Accounting Capability Attribute, VQ: Volume Quota, QID: QuotaIdPPAQ: Prepaid Accounting Operation Attribute, VTH: Volume-Threshold,
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Supported Features
Resource Pools• Service-A rated 1 €/MB Service-B rated 0 1€/MinService A rated 1 €/MB, Service B rated 0.1€/Min• 5 Euro worth of resources allocated to each service (5 MB and 50 Min)
P bl If Q t A ti i l th Q t B• Problem: If Quota-A consumption is slower than Quota-B
0 50 100 min
Service-AService-B
0 50 100 min
• Solution: Assign both Quotas to the same resource pool
Service-AService-B
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Resource Pool Multiple servicesResource pools
[allocates 5MBPoolr = 50 Units [allocates 5MB quota]
Poolr = 50 Units
[allocates 50 min quota]
Poolr = 50 + 50 = 100 Units 100 Units
C d 85[reimburses user
account]
Consumed 85 Units
SID: Service Id, DQ: Duration Quota Reimburse 15
Units
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Supported Features
Tariff Switching• Traffic before 18:00 is rated at rate r1 and traffic after 18:00 isTraffic before 18:00 is rated at rate r1 and traffic after 18:00 is
rated at rate r2.• If the PPS needs to signal a tariff switch time it will send a PTS
attribute that indicates the point in time when the switch will occur. This indication represents the number of seconds from current time (TariffSwitchInterval TSI)current time (TariffSwitchInterval TSI).
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Prepaid tariff switchingDuration-based Volume-basedTariff switching
[allocates 20MB quota]
[reimburses user account]
PTS: Prepaid Tariff SwitchingTSI: Tariff Switch IntervalVUATS: Volume Used After Tariff Switch
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Supported Features
Support for Roaming Dynamic TerminationDynamic Termination Multiple Tariff Switches One Time Events
• One Time Charging• Resource Consumption Query• Balance Check• Balance Check• Refund• Price Enquiry
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Summary
AAA Model: Authentication, Authorization, Accounting Radius Protocol and Use CaseRadius Protocol and Use Case Prepaid System in Charging Network Prepaid Extensions for Radiusp Radius vs Diameter?
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References T. S. D. Szilagyi, A. Sood, Radius A Remote Authentication Dial-in User Service, 2009. HP, HP-UX AAA Server A.06.00 Administration and Authentication Guide: HP-UX 11.0,
11i v1 HP 200311i v1, HP, 2003. OECD, Information and Communications Technologies, OECD Communications Outlook
2009, Oecd technical report, 2009. J Hassell Radius O’Reilly 2002 p 206J. Hassell, Radius, O Reilly, 2002, p. 206. E. P. Release, Pre-paid subscribers in charge, http://www.ericsson.com/news/1395590,
2010. A. Lior, P. Yegani, K. Chowdhury, H. Tschofenig and A. Pashalidis, Network WorkingA. Lior, P. Yegani, K. Chowdhury, H. Tschofenig and A. Pashalidis, Network Working
Group, Internet-Draft, http://tools.ietf.org/html/draft-lior-radiusprepaid-extensions-17, 2009
Eduroam. A technical Overview http://www.eduroamus.org/technical_overview http://schools-wikipedia.org/wp/c/Circle.htm
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Convergent Charging
Prepaid Postpaid
Convergent Charging
Prepaid Postpaid
Fixed Telephony Broadband TV Mobile
Telephony
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Additional References http://en.wikipedia.org/wiki/Convergent_charging http://www.ericsson.com/ericsson/corpinfo/publications/review/2009_01/files/Charging.pdf
htt // i hi http://www.iconarchive.com http://www.iconspedia.com
January 27, 2011| Edip Demirbilek | Prepaid Extensions for AAA Services Additional Slide 2 (2)