Lightpath Versus Semi-Lightpath: Some Studies on Optimal Routing in WDM Optical Networks

Lightpath Versus Semi-Lightpath: Some Studies on Optimal Routing in WDM Optical Networks This paper deals with the problem of optimal dynamic routing in WDM optical networks with wavelength-changing facilities available at some of the nodes. The route may be either a lightpath (i.e., wavelength continuous channel) or a semi-lightpath (i.e., wavelength-converted channel). We attempt to estimate in this work the gain in blocking probability, when we move from lightpath routing to semi-lightpath routing, keeping the number of wavelengths fixed, in a given circuit switched network. We ensure optimal (minimum cost) routing in both the cases by using the algorithm of Banerjee et al. [7,8] (called Algorithm-I in this paper) for lightpaths and that of Chlamtac et al. [6] (called Algorithm-II) for semi-lightpaths. Our results indicate that, for both the algorithms, the blocking probability (P B), as expected, increases with network load. At light load, P B for Algorithm-I is always larger than that for Algorithm-II. But the rate of increase in P B is slightly higher in case of Algorithm-II, so that there is a crossover point where P B for Algorithm-II exceeds P B for Algorithm-I. This probably happens due to the irregularities in the semi-lightpaths at heavy loads when almost all routes are exhausted in the network. However, since this crossover phenomenon occurs at a very congested status of the network, it has little significance over the real life operation of a network. It only suffices to indicate that, under heavy load, both the algorithms are equally insufficient, and conversion does not improve the situation as might have been expected intuitively. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Photonic Network Communications Springer Journals

Lightpath Versus Semi-Lightpath: Some Studies on Optimal Routing in WDM Optical Networks

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Publisher
Kluwer Academic Publishers
Copyright
Copyright © 2000 by Kluwer Academic Publishers
Subject
Computer Science; Computer Communication Networks; Electrical Engineering; Characterization and Evaluation of Materials
ISSN
1387-974X
eISSN
1572-8188
D.O.I.
10.1023/A:1010036422970
Publisher site
See Article on Publisher Site

Abstract

This paper deals with the problem of optimal dynamic routing in WDM optical networks with wavelength-changing facilities available at some of the nodes. The route may be either a lightpath (i.e., wavelength continuous channel) or a semi-lightpath (i.e., wavelength-converted channel). We attempt to estimate in this work the gain in blocking probability, when we move from lightpath routing to semi-lightpath routing, keeping the number of wavelengths fixed, in a given circuit switched network. We ensure optimal (minimum cost) routing in both the cases by using the algorithm of Banerjee et al. [7,8] (called Algorithm-I in this paper) for lightpaths and that of Chlamtac et al. [6] (called Algorithm-II) for semi-lightpaths. Our results indicate that, for both the algorithms, the blocking probability (P B), as expected, increases with network load. At light load, P B for Algorithm-I is always larger than that for Algorithm-II. But the rate of increase in P B is slightly higher in case of Algorithm-II, so that there is a crossover point where P B for Algorithm-II exceeds P B for Algorithm-I. This probably happens due to the irregularities in the semi-lightpaths at heavy loads when almost all routes are exhausted in the network. However, since this crossover phenomenon occurs at a very congested status of the network, it has little significance over the real life operation of a network. It only suffices to indicate that, under heavy load, both the algorithms are equally insufficient, and conversion does not improve the situation as might have been expected intuitively.

Journal

Photonic Network CommunicationsSpringer Journals

Published: Oct 8, 2004

References

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