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Description:
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We address two problems dealing with fault -tolerant communication in networks .
The first one is designing a distributed storage protocol tolerant to Byzantine failure of
servers . The protocol implements a multi -writer multi -reader register which satisfies
a weaker consistency condition called MWReg . Most of the earlier work gives multiwriter
implementations by simulating m copies of a single -writer protocol where m
is the number of writers . Our solution gives a direct multi -writer implementation
and thus has bounded message and time complexity independent of the number of
writers . We have simulated the complete protocol to test its performance and also
proved its correctness theoretically .
The second problem we address is of providing a reliable communication link
between two nodes in a network . We present a capacity reservation algorithm in the
case for upper bounds on edge capacities and costs associated with using per unit
capacity on any edge . We give a flow based approximation algorithm with cost at
most four times optimal .
To conclude , we design a distributed storage protocol and a capacity reservation
algorithm which are tolerant to network failures . |