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Type of publication:Article
Entered by:
TitleDirect Routing: Algorithms and Complexity
Bibtex cite IDRACTI-RU1-2006-77
Journal Algorithmica
Year published 2006
Month May
Volume 45
Number 1
Pages 45-68
DOI 10.1007/s00453-005-1189-3
Direct routing is the special case of bufferless routing where N packets, once injected into the network, must be routed along specific paths to their destinations without conflicts. We give a general treatment of three facets of direct routing: (i) Algorithms. We present a polynomial time greedy algorithm for arbitrary direct routing problems whch is worst-case optimal, i.e., there exist instances for which no direct routing algorithm is better than the greedy. We apply variants of this algorithm to commonly used network topologies. In particular, we obtain near-optimal routing time using for the tree and d-dimensional mesh, given arbitrary sources and destinations; for the butterfly and the hypercube, the same result holds for random destinations. (ii) Complexity. By a reduction from Vertex Coloring, we show that Direct Routing is inapproximable, unless P=NP. (iii) Lower Bounds for Buffering. We show the existence of routing problems which cannot be solved efficiently with direct routing. To solve these problems, any routing algorithm needs buffers. We give nontrivial lower bounds on such buffering requirements for general routing algorithms.
Busch, Costas
Magdon-Ismail, Malik
Mavronicolas, Marios
Spirakis, Paul
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Publication ID341