efficient routing and wavelength assignment in wavelength-routed optical networks johannes...
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Efficient Routing and Wavelength Assignment in Wavelength-Routed Optical Networks
Johannes Hamonangan SiregarDoctoral Program in Policy and Planning Sciences, University of Tsukuba,
1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8573, JapanEmail: [email protected] Tel:+81-29-853-5587
Hideaki TakagiVice President, University of Tsukuba
1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8577, JapanEmail: [email protected] Tel:+81-29-853-2005
Yongbing ZhangInstitute of Policy and Planning Sciences, University of Tsukuba
1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8573, JapanEmail: [email protected] Tel:+81-29-853-5071
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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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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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RWA Algorithms
Previous works: Longest first fixed path (LFFP) algorithm by Chlamtac et al. IEEE
Trans. Comm., 1992. 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, 1997. 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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LFAP Algorithm
The RWA problem is formulated as a knapsack problem as follows:
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HPLD Formulation
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Flowchart of Our Algorithms
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Results of Previous Algorithms
4
Number of wavelengths required = 6 Number of wavelengths required = 4
MNHLFFP
56
7
2
3
8
4
1
2
6
73
8
5
4
(s,d) lightpaths Wl
(4,5) 4-2-1-5
(4,7) 4-3-7
(5,8) 5-7-8 w1
(5,6) 5-6
(6,7) 6-7
(1,8) 1-2-4-8
(1,7) 1-3-7
(6,8) 6-7-8 w2
(3,4) 3-4
(5,7) 5-7
(2,6) 2-1-5-6 w3
(3,8) 3-4-8
(2,7) 2-1-3-7 w4
(1,4) 1-2-4 w5
(2,3) 2-1-3 w6
(s,d) lightpaths Wl
(4,5) 4-2-1-5
(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) 2-1-3-7 w3
(3,4) 3-4
(5,6) 5-6
(2,3) 2-4-3
(1,8) 1-3-7-8 w4
(2,6) 2-1-5-6
(6,7) 6-7
1
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Result of Our Algorithms
Number of wavelengths required = 4 Number of wavelengths required = 4
3
15
6
73
2
4
8
15
6
3 7
2
4
8
(s,d) lightpaths wl
(4,5) 4-2-1-5
(4,7) 4-3-7
(5,8) 5-7-8 w1
(5,6) 5-6
(6,7) 6-7
(1,8) 1-2-4-8
(1,7) 1-3-7
(6,8) 6-7-8 w2
(3,4) 3-4
(5,7) 5-7
(2,6) 2-1-5-6 w3
(3,8) 3-4-8
(2,7) 2-1-3-7
(1,4) 1-5-7-8-4 w4
(2,3) 2-4-3
(s,d) lightpaths wl
(2,3) 2-4-8-7-3
(2,6) 2-1-5-6
(3,4) 3-4 w1
(5,7) 5-7
(6,7) 6-7
(1,4) 1-5-7-8-4
(2,7) 2-1-3-7 w2
(5,6) 5-6
(4,5) 4-2-1-5
(1,7) 1-3-7
(3,8) 3-4-8 w3
(5,8) 5-7-8
(1,8) 1-2-4-8
(6,8) 6-7-8 w4
(4,7) 4-3-7
LFAP HPLD
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Kanto Network
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Comparison of Algorithms
Number of wavelengths Computation time
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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