隨著網際網路對於頻寬需求的持續成長，採用高密度光波分割多工技術的光網路已成為未來骨幹網路的最佳選擇。雖然因為光纖鏈結中波長個數的增加可以大幅提升頻寬，卻也造成光波交錯連結器交換埠口數目急遽地成長。顯然照此局勢發展，在控制及管理如此大型交錯連結器架構將愈加複雜之態勢已然可以預見。在此篇論文中，我們針對光波段網路下繞徑及波長的配置之問題加以研究。我們所考量的光波段網路是由多層次型交錯連結器所組成，同時這些多層次型交錯連結器透過光纖鏈結相連接。架構於多層次型交錯連結器的光波段網路可以在同時間以各種不同的層次來處理資料流的繞徑，其中包括光纖、光波段及波長三種層次；因此負責處理交換動作的元件架構之大小得以有效的縮小。更進一步地，為了放寬建立光路徑時波長連續性的限制，我們假設每個節點的多層次型交錯連結器上皆裝設了特定數目的波長轉換器。
　　針對動態資料流的環境下，我們提出了一個啟發式演算法稱為有限轉換之最少調整演算法，主要專注於將額外的埠口消耗量降至最低並有效的運用波長轉換器。當新的連線要求抵達，有限轉換之最少調整演算法先採用固定繞徑演算法以解決繞徑及波長配置問題中繞徑的部份。而波長配置的部份則運用階層式圖形法及新提出的成本計算函式來尋找適當的波長。我們將提出的演算法跟先前已經被提出的演算法加以比較，並給定不同程度的資料流負載以觀察兩者在網路效能及波長轉換器使用率上的表現。藉由模擬實驗的結果可以發現我們所提出的演算法能夠比較有效的進行光波段編組動作，因此可以大幅度降低連線要求的阻斷機率使得網路效能能夠顯著獲得改善。

　　With ever-increasing Internet bandwidth demand, optical networks with Dense Wavelength Division Multiplexing (DWDM) technology are an attractive candidate for the future Internet backbone. Although the increase in number of wavelengths within a fiber link provides tremendous bandwidth, it also brings about a great deal of switching ports at optical cross-connects (OXCs). Consequently, it is expected that higher and higher complexity is inevitable to control and manage such large OXCs. In the thesis, we study the routing and wavelength assignment (RWA) problem in waveband switching (WBS) networks, which is composed of multi-granular OXCs (MG-OXCs) interconnected by fiber links. WBS networks with MG-OXCs can route traffic at multiple granularities, including fiber, waveband and wavelength, at the same time; therefore, the size of switching fabrics can be efficiently reduced. Moreover, in order to relax the wavelength continuity constraint on lightpath establishments, each MG-OXC node is equipped with certain number of wavelength converters.
　　Focused on minimizing the extra port consumption and utilizing wavelength converters in an efficient manner, we propose a heuristic algorithm named Least-Configuration with Bounded Conversion (LCBC) for the dynamic traffic environment. For a new connection request, LCBC adopts fixed routing first to solve the routing sub-problem, and exploits the layered-graph approach and a novel cost function to search desired wavelength(s). We compare the blocking performance and converter utilization between LCBC and previously proposed WAPG algorithm under various traffic loads. The simulation based results show that LCBC provides higher benefit in waveband grouping, resulting in a significant improvement in terms of blocking probability.

[1]　Fahad A. Al-Zahrani, Abdulgader A. Habiballa, Ayman G. Fayoumi, and Anura P. Jayasumana; "Performance tradeoffs of shared limited range wavelength conversion schemes in optical WDM networks," IEEE WOCN 2005, March 2005, pp. 18 - 22.
[2]　Dhritiman Banerjee and Biswanath Mukerjee; "A practical approach for routing and wavelength assignment in large wavelength-routed optical networks," Selected Areas in Communications, IEEE Journal on, Volume 14, Issue 5, June 1996, pp. 903 – 908.
[3]　Xiaojun Cao, Vishal Anand, Jikai Li, and Chunsheng Xin; "Waveband switching networks with limited wavelength conversion," IEEE Communications Letters 2004, Volume 9, Issue 7, July 2005, pp. 646 - 648.
[4]　Xiaojun Cao, Vishal Anand, and Chunming Qiao; "Waveband switching in optical networks," IEEE Communications Magazine 2003, Volume 41, Issue 4, April 2003, pp.105-112.
[5]　Xiaojun Cao, Vishal Anand, and Chunming Qiao; "A waveband switching architecture and algorithm for dynamic traffic," IEEE Communications Letters 2003, Volume 7, Issue 8, August. 2003, pp.397-399.
[6]　Xiaojun Cao, Vishal Anand, and Chunming Qiao; "Multi-layer versus single-layer optical cross-connect architectures for waveband switching," IEEE INFOCOM 2004, Volume 3, pp.1830-1840.
[7]　Xiaojun Cao, Vishal Anand, Yizhi Xiong, and Chunming Qiao; "A study of waveband switching with multilayer multigranular optical cross-connects," IEEE JSAC 2003, Volume 21, Issue 7, September. 2003, pp.1081-1095.
[8]　Xiaojun Cao, Chunming Qiao, Vishal Anand, and Jikai LI; "Wavelength assignment in waveband switching networks with wavelength conversion," IEEE GLOBECOM 2004, Volume 3, November - December 2004, pp. 1943 - 1947.
[9]　Li-Wei Chen, Poompat Saengudomlert, and Eytan Modiano; "Optimal waveband switching in WDM networks," IEEE ICC 2004, Volume 3, June 2004, pp.1604-1608.
[10]　Samrat Ganguly, Nan Tu, Rauf Izmailov, and Hussein T. Mouftah; "Waveband routing and merging in hybrid optical networks," IEEE ICC 2004, Volume 3, June 2004, pp.1615-1621.
[11]　Ori Gerstel, Rajiv Ramaswami and Weyl-Kuo Wang; "Making use of a two stage multiplexing scheme in a WDM network," IEEE OFC 2000, Volume 3, March 2000, pp.44-46.
[12]　Ching-Fang Hsu, Te-Lung Liu, and Fang-Sheng Lin; "On dynamic routing and wavelength assignment in multi-granular all-optical networks," IEEE ICITA 2005, Volume 1, July 2005, pp.537-542.
[13]　Rauf Izmailov, Samrat Ganguly, and Chunming Qiao; "Non-uniform waveband hierarchy in hybrid optical networks," IEEE INFOCOM 2003, Volume 2, March-3 April, 2003, pp. 1344-1354.
[14]　Rauf Izmailov, Samrat Ganguly, Ting Wang, Yoshihiko Suemura, Yoshiharu Maeno, and Soichiro Araki; "Hybrid hierarchical optical networks," IEEE Communications Magazine 2003, Volume 40, Issue 11, November, 2002, pp. 88-94.
[15]　Aleksandar Kolarov, Ting Wang, Bhaskar Sengupta, and Milorad Cvijetic; "Impact of waveband switching on dimensioning multi-granular hybrid optical networks," Optical Network Design and Modeling, 2005. Conference on, February 2005, pp. 371 - 381.
[16]　Mengke Li, and Byrav Ramamurthy; "A graph model for dynamic waveband switching in WDM mesh networks," IEEE ICC 2004, Volume 3, June 2004, pp.1821-1825.
[17]　Mengke Li, Wang Yao, and Byrav Ramamurthy; "Same-destination-intermediate grouping vs. end-to-end grouping for waveband switching in WDM mesh networks," IEEE ICC 2005, Volume 3, May 2005, pp. 1807 – 1812.
[18]　Biswanath Mukherjee; "WDM optical communication networks: progress and challenges," Selected Areas in Communications, IEEE Journal on, Volume 18, Issue 10, October 2000, pp. 1810 – 1824.
[19]　C.Siva Ram Murthy and Mohan Gurusamy; "WDM optical networks: concepts, design, and algorithms," Prentice Hall 2002
[20]　Ludovic Noirie, Francois Dorgeuille, and Arnaud Bisson; "30 × 10 gbit/s DWDM metropolitan network demonstration with 10 waveband-ADMs and 155km TeraLight Metro fiber," IEEE OFC 2002, March, 2002, pp. 442 – 443.
[21]　Ludovic Noirie, Martin Vigoureux, and Emmanuel Dotaro; "Impact of intermediate traffic grouping on the dimensioning of multi-granularity optical networks," IEEE OFC 2001, Volume 2, 2001, pp. TuG3-1 – TuG3-3.
[22]　Rajiv Ramaswami and Kumar N. Sivarajan; "Routing and wavelength assignment in all-optical networks," Networking, IEEE/ACM Transaction on, Volume 3, Issue 5, October 1995, pp. 489 – 500.
[23]　Hui Zang, Jason P. Jue, Laxman Sahasrabuddhe, Ramu Ramamurthy, and Biswanath Mukherjee, ; "Dynamic lightpath establishment in wavelength routed WDM networks," IEEE Communications Magazine 2001, Volume 39, Issue 9, September, 2001, pp. 100-108.
[24]　Ding Zhemin and Mounir Hamdi; "On the management of wavelength converter allocation in WDM all-optical networks," IEEE GLOBECOM 2003, Volume 5, 2003, pp. 2595 – 2600.