| Abstract |
Recent years have seen the emergence of the deployment of many distributed
systems of global scale. In addition, one of the age-long requirements and goals of
distributed systems is the attainment of large degree of scalability, the ability of a
system to cope with ever increasing number of participants. As one of the solutions
to this problem, the Peer-to-Peer (P2P) paradigm was introduced and immediately
received increasing attention. This leads to the quick evolution of the P2P systems,
which branched out into two main categories, namely the structured and the
unstructured systems. Structured systems are based on a more sophisticated way of
interconnection between the participants of the system, which enables more efficient
communication primitives. At the same time, this rigidness limits the scalability of
those systems. Unstructured systems, on the other hand, are based on a more loose
interconnection structure. Although this structure makes it easier for those systems to
scale to global deployment, the communication primitives are less efficient, thus
limiting their scaling ability. In this thesis we present an effort to tackle this
problem of unstructured systems in many levels. We develop novel algorithms which
enable the communication primitives of unstructured systems to better scale to a
higher number of participants by reducing the functional costs not only for the P2P
system itself but also for the network medium used. Contributions of this thesis
include (i) a novel broadcast-like technique which generates a much smaller amount
of network traffic, (ii) a new participants interconnection structure which enables
more sophisticated search methods without transforming an unstructured system to a
structured one and (iii) another, complementary or stand-alone method to create the
P2P overlay so as to allow the system to work in the same manner a before, but at
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the same time reducing the traffic load imposed on the network medium used by the
system.
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Improving Routing in Unstructured Peer-to-Peer Systems
