As computers become pervasive and better
connected, the popularity of peer-to-peer
computing has grown immensely. The sharing of
unused resources at peers is desirable and
practically important because they can
collectively comprise a powerful system. The
potential benefit, however, can be undermined by
uncooperative behavior of some peers because they
are managed individually and hence may not follow
the expected protocols. To build robust systems,
we must incorporate proper trust and incentive
mechanisms so that peers would rather cooperate.
In this dissertation, we demonstrate that building
robust peer-to-peer information dissemination
systems is important and viable, using four
concrete cases. First, we investigate the
incentive mechanism of BitTorrent, an
exchange-based file distribution protocol. Our
framework based on iterated prisoner's dilemma
provides an insight into users' tension between
eagerness to download and unwillingness to upload.
By using both analytical and experimental
approaches, we show that the current incentive
mechanism of BitTorrent is susceptible to free
riding. We propose an improved mechanism that
punishes free riders effectively. Second, we
present a trust-aware overlay multicast system
that performs well in the presence of
uncooperative nodes, which may block, delay,
fabricate, or forge the messages they forward. We
develop (1) a set of protocols that detect
uncooperative behavior, (2) a scheme of trust
value assignment according to the behavior of
nodes, and (3) an algorithm that adapts the
multicast tree based on trust values, all of which
allows the system to remain stable and responsive
over time. Third, we propose an alternative news
feed dissemination system, called FeedEx, in which
feed subscribers mesh into a network and exchange
news feeds with neighbors. The collaborative
exchange in FeedEx, with the help of the
incentive-compatible design using the pair-wise
fairness principle, reduces the server load and
hence increases the scalability. Fourth, we
introduce a new concept of peer-to-peer computing,
that is, continual service using ephemeral
servers. To this end, we develop a system model
for the concept and implement a discrete-time
simulator to find the conditions and the system
support for eliciting cooperation. All four cases
are substantiated by experimental results.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/14037 |
| Date | 21 November 2006 |
| Creators | Jun, Seung Won |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | 1258277 bytes, application/pdf |
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