ISSN : 1796-2056
Volume : 3    Issue : 3    Date : March 2008

Dominating Set Theory based Semantic Overlay Networks for Efficient and Resilient Content
J. Amutharaj and S. Radhakrishnan
Page(s): 42-48
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Recently overlay networks have emerged as an efficient and flexible method for content distribution.
An overlay network is a network running on top of another network, usually the Internet. This network
is formed by a subset of underlying physical nodes. The connections between the overlay nodes are
provided by overlay links, each of which is usually composed of one or more physical link. These
networks are employed in many settings to provide logical communication infrastructure over an
existing communication networks. The main objective of the overlay network is to reduce routing
path lengths, stretched by the overlay routing process. In the existing solutions developed, a kind of
fixed infrastructure in the form of excessive message exchange is necessary to guarantee good
overlay properties.
The scope of our effort is to construct an overlay network based on Dominating Set Theory to
optimize the number of nodes for large data transfer. Fast Replica algorithm is applied to reduce the
content transfer time for replicating the content within the semantic network. A dynamic parallel
access scheme is introduced to download a file from different peers in parallel from the Semantic
Overlay Network (SON), where the end users can access the members of the SON at the same
time, fetching different portions of that file from different peers and reassembling them locally. That
is, the load is dynamically shared among all the peers. To eliminate the need for retransmission
requests from the end users, an enhanced digital fountain with Tornado codes is applied. Decoding
algorithm at the receiver will reconstruct the original content. In this no feedback mechanisms are
needed to ensure reliable delivery. This paper analyzes the performance of sequential unicast,
multiple unicast and fast replica with tornado content distribution strategies in terms of content
replication time and delivery ratio. This paper also analyzes the impact of dominating set theory for
the construction of semantic overlay networks.

Index Terms
Semantic Overlay Networks, Dominating Set Theory, Multicasting, Fast Replica, Content
Distribution, Replication Time, Delivery Ratio.