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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 1 Routing and Wavelength Assignment for Wavelength-Routed WDM Networks Combined routing and wavelength assignment problem Routing u static: ILP formulation u dynamic: on-line algorithms Wavelength assignment u static: graph coloring approach u dynamic: heuristics A new wavelength assignment heuristic
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 2 RWA Problem statement Wavelength-continuity constraint
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 3 Combined Routing and Wavelength Assignment Problem
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 4 Routing - ILP Formulation
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 5 Routing - Algorithms For Dynamic Traffic Fixed routing (On/Off line) Fixed-alternate routing (On/Off line) Adaptive routing (On line) u adaptive shortest path routing u least congested path routing
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 6 Wavelength Assignment with Known Lightpaths and Routes - Graph Coloring Construct an auxiliary graph G(V,E) Color the nodes of the graph G such that no two adjacent nodes have the same color Sequential graph coloring approaches
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 7 Wavelength Assignment Heuristics Random First-Fit Least-Used/SPREAD Most-Used/PACK Min-Product Least Loaded MAX-SUM Relative Capacity Loss Wavelength Reservation Protecting Threshold
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 8 Illustrative Example 0123456 wavelengthsP 1 :(2,4) 3 2 1 0 Note: control network not shown. All wavelengths shown are for data traffic
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 9 Calculation of Max-Sum Wavelength selected: 0, 1, or 3 WPC: Wavelength-path Capacity 0123456 wavelengthsP 1 :(2,4) 3 2 1 0
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 10 Calculation of Relative Capacity Loss Wavelength selected: 1 or 3 0123456 wavelengthsP 1 :(2,4) 3 2 1 0
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 11 Simulation Network Connection management protocol: link-state 1 5 0 4 3 2 1 1 1 1 1 1 2 2
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 12 Results from Others’ Publication Source: S. Subramaniam and R. A. Barry, “Wavelength assignment in fixed routing WDM networks,” Proc. ICC'97 - International Conference on Communications, Montreal, Canada, vol. 1, pp. 406-410, June 1997. (a)(b) R R MS MU, MS WC FF, MU WC FF 20-node unidirectional ring, load/W = 1 Erlang # of wavelengths 5x5 bidirectional mesh-torus, load/W = 25 Erlangs
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 13 Computational Complexity Wavelength reservation & Protecting threshold - constant Random & First-Fit - O(W) Min-Product & Least-Loaded - O(NW) Least-Used & Most-Used - O(LW) Max-Sum & Relative Capacity Loss - O(WN 3 ) where W - # of wavelengths, N - # of nodes, L - # of links
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 14 Distributed RCL Algorithm 0123456 P 1 :(2,4) 3 2 1 0 RCL table at Node 2 * Wavelength selected: 3
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 15 Characteristics of Distributed RCL Less state information is exchanged Faster computation of wavelength assignment upon a connection request Can be combined with adaptive routing
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 16 Simulation Network Average propagation delay between two nodes: 0.107 ms Average hop distance: 1.53 1 5 0 4 3 2 1 1 1 1 1 1 2 2
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 17 Simulation Results of Distributed RCL Comparison of DRCL with adaptive routing and RCL with fixed routing
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 18 Conclusion for RWA L: # of links, N: # of nodes, W: # of wavelengths
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 19 Future Research Survivable wavelength-routed WDM networks u previous work: static traffic & single link failure [S. Ramamurthy 1998] u higher layer protection -logical topology design with bundle cut in mind u WDM layer protection - dynamic traffic
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ECS 259 -- H. Zang and B. Mukherjee, UC Davis 20 Future Research (Cont’d) Managing multicast connections in wavelength-routed WDM networks u KMB u Bellman-Ford u Chain
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