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Efficient Routing and Wavelength Assignment in Wavelength-Routed Optical Networks Johannes Hamonangan Siregar Doctoral Program in Policy and Planning Sciences, University of Tsukuba, Tennoudai, Tsukuba-shi, Ibaraki , Japan Tel: Hideaki Takagi Vice President, University of Tsukuba Tennoudai, Tsukuba-shi, Ibaraki , Japan Tel: Yongbing Zhang Institute of Policy and Planning Sciences, University of Tsukuba Tennoudai, Tsukuba-shi, Ibaraki , Japan Tel:

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(2)(2) APNOMS 2003 Introduction Wavelength division multiplexing (WDM) optical network offers a great potential for future high speed applications in large-scale networks because of its wide bandwidth and high-speed data transmission The optical communication path between a pair of a source and a destination is called a lightpath We consider the routing and wavelength assignment (RWA) for large-scale WDM optical networks where each transmission request is served by an all-optical lightpath without wavelength conversion

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(3)(3) APNOMS 2003 RWA Problem To establish a lightpath, we need to determine –The path (route) from the source to destination –Assignment of a wavelength to the path Static lightpath establishment problem –The set of connection requests is known in advance –The objective is to minimize the number of wavelengths used Dynamic lightpath establishment problem –Connection requests arrive to the network dynamically –The objective is to minimize the connection blocking probability We consider the static lightpath establishment problem

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(4)(4) APNOMS 2003 RWA Algorithms Previous works: Longest first fixed path (LFFP) algorithm by Chlamtac et al. IEEE Trans. Comm., They use only fixed shortest paths for all s-d pairs and assign a wavelength to the longest path first Minimum number of hops (MNH) algorithm by Baroni and Bayvel, IEEE/OSA JLT, They use alternate shortest paths to decrease the heaviest load and assign a wavelength to the longest path first Our algorithms : Longest first alternate path (LFAP). We use alternate paths for s-d pairs that cannot be established by shortest paths only and assign a wavelength to the longest path first Heaviest path load deviation (HPLD). We determine the initial lightpaths using LFFP and then deviate the path load for some s-d pairs that pass through the heaviest link to minimize the number of wavelengths

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(5)(5) APNOMS 2003 LFAP Algorithm The RWA problem is formulated as a knapsack problem as follows:

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(6)(6) APNOMS 2003 HPLD Formulation

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(7)(7) APNOMS 2003 Flowchart of Our Algorithms

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(8)(8) APNOMS 2003 Results of Previous Algorithms 4 Number of wavelengths required = 6 Number of wavelengths required = 4 MNH LFFP (s,d) lightpaths Wl (4,5) (4,7)4-3-7 (5,8)5-7-8 w1 (5,6)5-6 (6,7)6-7 (1,8) (1,7)1-3-7 (6,8)6-7-8 w2 (3,4)3-4 (5,7)5-7 (2,6) w3 (3,8)3-4-8 (2,7) w4 (1,4)1-2-4 w5 (2,3)2-1-3 w6 (s,d) lightpathsWl (4,5) (1,7)1-3-7 w1 (3,8)3-4-8 (1,4)1-2-4 (4,7)4-3-7 w2 (6,8)6-7-8 (5,7)5-7 (5,8)5-7-8 (2,7) w3 (3,4)3-4 (5,6)5-6 (2,3)2-4-3 (1,8) w4 (2,6) (6,7)6-7 1

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(9)(9) APNOMS 2003 Result of Our Algorithms Number of wavelengths required = (s,d) lightpathswl (4,5) (4,7)4-3-7 (5,8)5-7-8 w1 (5,6)5-6 (6,7)6-7 (1,8) (1,7)1-3-7 (6,8)6-7-8 w2 (3,4)3-4 (5,7)5-7 (2,6) w3 (3,8)3-4-8 (2,7) (1,4) w4 (2,3)2-4-3 (s,d) lightpathswl (2,3) (2,6) (3,4)3-4 w1 (5,7)5-7 (6,7)6-7 (1,4) (2,7) w2 (5,6)5-6 (4,5) (1,7)1-3-7 (3,8)3-4-8 w3 (5,8)5-7-8 (1,8) (6,8)6-7-8 w4 (4,7)4-3-7 LFAP HPLD

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(10) APNOMS 2003 Kanto Network

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(11) APNOMS 2003 Comparison of Algorithms Number of wavelengths Computation time

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(12) APNOMS 2003 Conclusion LFAP and HPLD yield a less number of wavelengths than LFFP and MNH by using not only alternate shortest paths LFAP and HPLD provide less computational complexity than MNH, because –LFAP assigns a wavelength to the longest path first –HPLD deviates the load of the heaviest path to the lightest paths

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