Transcript Peer WLAN Consortium: A P2P Case Study Mobile Multimedia Laboratory Department of Informatics Athens University of Economics & Business Athens MMAPPS Meeting, September 23-25, 2002

Peer WLAN Consortium:
A P2P Case Study
Mobile Multimedia Laboratory
Department of Informatics
Athens University of Economics &
Business
Athens MMAPPS Meeting, September 23-25, 2002
Motivation
• WLANs are becoming ubiquitous:
• WLAN access points (APs) are easy to setup.
• WLAN PC users are increasing by the millions.
• Devices with WLAN interfaces achieve throughput in the Mbps range.
• WLAN access control schemes
are being introduced to minimize
the effects of uncontrolled
wireless connections.
• Figure: The 802.1X framework.
• Introduction of incentive mechanisms could allow controlled wireless
access in a P2P fashion.
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Definition
• Peer WLAN Consortium:
– A community of peer networks that offers better
geographical coverage than any one of its
members.
– The “peers” are WLAN administrative domains.
– A WLAN administrative domain is a collection of
APs, connected to an Authentication Server.
• These elements collectively implement one Authentication
Policy for the domain.
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Consortium Elements
U
U
AD1
AP
AP
U
U
AS
+
Policy
AP
AD2
AS
+
Policy
U
U
U
AP
AP
U
U
AD3
AP
U
AS
+
Policy
U
U
U
AP
AP
U
Consortium
AP
AP: Access Point
U : User
AS: Authentication Server
AD: Administrative Domain
Hotspot network view
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P2P view
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Description
• Users within the same consortium can be identified
as such by any member domain. Consequently, they
may be granted WLAN access.
• The consortium is not controlled by any central or
external entity.
• The peers are independent and may have different
attributes.
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Peer Attributes
• Number of registered users.
• Hotspot network, and, for each hotspot, its:
• Geographical location.
• Bandwidth to the Internet.
• IP subnet size.
• Value added services, such as:
• Digital library access.
• Location-specific information.
• MBONE access.
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Peer Status
• A peer’s status at any one time includes:
– Users connected to it, along with their:
• Location.
• Type (home users vs. visiting users).
– Bandwidth utilization.
– Services utilization.
• Global state of the consortium.
– Composed of each peer’s current status.
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P2P Aspects
• The consortium is governed by rules on reciprocity
that are flexible.
• Incentives to share a domain’s resources are
needed.
• The basic objective is to provide wireless access.
• Each peer attempts to maximize the benefit for its
registered users:
•
•
•
•
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Increase geographical coverage and availability.
Enhance performance.
Provide value-added services.
Ensure QoS levels (prevent abuse from visiting users).
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P2P Aspects (cont’d)
• Reputation system.
– Each peer wants to know what the other peers are offering.
– Different types of reputation:
• Service reputation.
• Network QoS reputation.
– Each peer can devise strategies based on this information.
• Free-riding represents a problem.
• As, for example, when peers deny access to visitors.
• Repeated game.
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Differences from Existing Schemes
• Current WISP schemes usually create their hotspot
networks on top of a centralized AAA platform.
• Especially true for GSM/WLAN hybrid wide-area WISPs,
which reuse GSM SIM card authentication.
• Other associations that attempt to set WLAN roaming
standards (such as Pass-One) prefer centralized
roaming management.
• They also mandate a large number of procedures. (Tight
rules vs. flexible rules.)
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Concluding Remarks
• The consortium scheme is compatible with any 802.1X
compliant WLAN infrastructure.
• One required addition is consortium software running on the
Authentication Server.
• It’s easy for pre-existing WLAN administrative domains to
become members.
• Following certain preconditions.
• Without having to rethink their whole architecture.
• No central or external entity controls peer decisions. These
decisions are made independently and are influenced by
incentive mechanisms.
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