1. Budapest, August 31, 2012
EUNICE 2012
The Design of a Single Funding Point
Charging Architecture (SFP-CA)
Christos Tsiaras, Martin Waldburger, Guilherme Sperb Machado,
Andrei Vancea, Burkhard Stiller
{tsiaras,waldburger,machado,vancea,stiller}@ifi.uzh.ch
Department of Informatics IFI, Communication Systems Group CSG,
University of Zürich UZH
Motivation
Requirements
Components
Architecture
© 2012 UZH, CSG@IFI 1

2. Motivation
 Institution & federation expenses decrease
– Cautious user resources requests
– Unnecessary infrastructure replication avoidance
 User- instead of service-dependent funding accounts
– A missing feature from Single Sign-on (SSO) systems
– Not the case in the majority of federations today
 Inter-domain charging capability
– Make sense for costly services
• NOT for eduroam / YES for printing, Short Message Service (SMS), VoIP
– Today this is a privilege only for Mobile Network Operators (MNOs)
and banks
 Real-time service access decision making functionality
– Today is mainly offered only by MNOs
 A Single Funding Point Charging Architecture (SFP-CA) as an add-on for
SSO systems in federated environments is essential
© 2012 UZH, CSG@IFI 2

3. Use case: SMS service @ ETHZ
 SMS offered by the Eidgenössische Technische Hochschule
Zürich (ETHZ)
– SMS gateway
– Agreement with an operator
• The more SMS are sent the better the price per SMS is
 Assume that the University of Zurich (UZH) is willing to offer
the same service
– A second SMS gateway is needed
• Infrastructure cost (purchase, setup, maintain)
– A separate agreement with an operator is needed
• Best case: The same price will be achieved
 Low SMS service load @ ETHZ
– The existing infrastructure could serve all federation members
– Better agreement with the SMS operator could be achieved!
© 2012 UZH, CSG@IFI 3

4. SFP-CA Requirements
user organization
Virtual Virtual
Funds Funds
Account Account
Interruption Service Trigger
SMS: 10 BC Service Service
Min: 0 BC
Tariff Usage
.
. Map Constraints and
.
Limits
© 2012 UZH, CSG@IFI 4

5. Virtual Funds Accounts (VFAs)
 uVFA
– One per user
– Credits used to pay the
requested resources
– In postpaid solutions negative
values are allowed
– Created by user's IdP
 oVFA
– Each organization has one oVFA for every
other organization in the federation x oVFA(B)
– If a user from organization A use
↑↓
resources at B then oVFA(A) ↓ and
oVFA(B) ↑ oVFA(A) 0 oVFA(B)
• If a payment has been done then ↓↑
oVFA(A) = oVFA(B) = 0 oVFA(A) -x
• If oVFA(A) + oVFA(B) ≠ 0 then Charging
Data Record (CDR) transfer error occurred
© 2012 UZH, CSG@IFI 5

6. SFP-CA Components
Organization  Service Provider Manager (SPM)
– Service Providers (SPs) and users
Service Provider Manager location-independent charging
Charging
Rate
Manager
SMS: 10 BC
Min: 0 BC
.
.
 Charging Rate Manager (CRM)
– Support of event- and session-
.
Service
Provider
Identity
Provider
based services
User
 Account Balance Manager (ABM)
Account – Support of prepaid and postpaid
Balance
Manager payment method
 Charging Manager (CM)
– Support of multiple organizations,
Charging which belong on the same
Manager
federation
Authentication and Authorization Infrastructure (AAI) / Single Sign-On (SSO) System
© 2012 UZH, CSG@IFI 6

7. Charging scenarios that can be
handled by the SFP-CA
The service is provided
to the user by...
his home organization a foreign organization
which is charging... which is charging...
an user's home
the user using a... ins dt
titu hen organization, using a...
tio use
n w r 's
ill c ho
ha me
offline charging online charging rg e offline charging
...
method method method
- VoIP - VoIP - VoIP
- Printing - Printing - SMS
© 2012 UZH, CSG@IFI 7

8. SFP-CA
Service Usage
Organization A organization Organization B
Constraints &
Virtual Funding Account oVFA SUCL
Limits
Service Provider Manager
Charging Interruption
Rate
Manager
Service
Tariff
Service
Trigger
This domain does not offer a service
Map Service
Provider
Identity
Provider IdP
User User
Account user
Balance Virtual Funding Account uVFA ABM
Manager
Charging
Manager CM
AAI / SSO System
One-time interaction Service request
Multiple times interaction
© 2012 UZH, CSG@IFI 8

9. Summary & future work
 The SFP-CA enables the inter-domain charging
functionality for federations
– User & organization level
 The SFP-CA enables the real-time service access decision
making
– Grant access
– Interrupt service
 The SFP-CA handles a large scenario set of charging
requests
– Local & guest users
– Event & session based services
– Offline & online charging
 SSO system + SFP charging mechanism => Efficiency
 Implementation of the SFP-CA (printing, SMS, VoIP)
© 2012 UZH, CSG@IFI 9

10. Q&A
© 2012 UZH, CSG@IFI 10