Efficient Routing and Wavelength Assignment in Wavelength-Routed Optical Networks

1. Johannes Hamonangan Siregar Doctoral Program in Policy and Planning Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8573, Japan Email: siregar@sk.tsukuba.ac.jp Tel:+81-29-853-5587 Hideaki Takagi Vice President, University of Tsukuba 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8577, Japan Email: takagi@sk.tsukuba.ac.jp Tel:+81-29-853-2005 Yongbing Zhang Institute of Policy and Planning Sciences, University of Tsukuba 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8573, Japan Email: ybzhang@sk.tsukuba.ac.jp Tel:+81-29-853-5071 Efficient Routing and Wavelength Assignment in Wavelength-Routed Optical Networks

2. Introduction • Wavelength division multiplexing (WDM) opticalnetwork 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

3. 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

4. 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 minimizethe number of wavelengths

5. LFAP Algorithm The RWA problem is formulated as a knapsack problem as follows:

6. HPLD Formulation

7. Flowchart of Our Algorithms

8. Resultsof Previous Algorithms 5 8 7 6 1 8 4 1 7 3 3 2 2 LFFP MNH 6 5 4 4 Number of wavelengths required = 6 Number of wavelengths required = 4

9. Result of Our Algorithms 1 5 6 7 3 2 8 4 5 6 3 7 2 4 8 1 LFAP HPLD 3 Number of wavelengths required = 4 Number of wavelengths required = 4

10. Kanto Network

11. Comparison of Algorithms Number of wavelengths Computationtime

12. 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