彈性光網路是一種新型態的網路結構，相較於之前的波長分波多工光網路，彈性光網路擁有更小的粒度，並能更有效地給連線需求配置資源。在網路多媒體的高速發展之下，使用者對於服務品質的要求越來越大，因此如何在有服務品質的需求底下進行繞徑與頻譜配置將會是一個需要被討論的問題。
這篇論文內主要討論兩種服務品質－固定速率連線服務及可變速率連線服務。據我們的了解，目前並沒有其他的文獻在彈性光網路底下討論固定速率連線服務及可變速率連線服務。對於固定速率連線服務我們提出兩種繞徑與頻譜配置的演算法來進行實驗分析，而繞徑與頻譜配置的問題也從單純的配置演變成排程的問題。兩種演算法分別為固定速率連線搭配K條最短路徑以及固定速率連線搭配輔助圖。對於可變速率連線服務的部分，我們分別提出了網路升速及網路降速的程序來達到網路交通的控制。以固定速率連線的演算法作為基礎，再搭配可變速率連線服務的網路升速及降速就可以達到服務品質的要求。
彈性光網路在繞徑與路由配置的問題中，有個問題是頻譜資源碎裂化，這個問題會使得頻譜資源不平整，進而影響繞徑與路由找到配置解的機率。在本論文設定的環境中，可以藉由調整未來的排程搭配升降速這種方式，來達到在不影響現有的連線之下進行頻譜重整，進而提升繞徑與路由配置的成功率。
數據結果顯示搭配輔助圖的繞徑與路由配置可以在較低流量時得到很好的配置成功率，並在升降速搭配頻譜重整的機制底下更進一步使連線阻斷率更低。

Elastic optical networks (EONs) is a new type of optical switching paradigm. Compared to wavelength-division multiplexing (WDM) optical networks, EONs has a more flexible granularity and can serve requests in a more efficient way. Due to the rapid growth in multimedia networks, demands with certain level of quality of service (QoS) requirements would be more and more prevalent. So, to accommodate the routing and spectrum assignment (RSA) problem subject to users’ QoS requirements evolves into an important issue in EONs.
In this thesis, two categories of traffic are considered: constant bit rate (CBR) and available bit rate (ABR). To the best of our knowledge, there has no other literature considering both CBR and ABR traffic in EONs. We propose two RSA algorithms for CBR requests, the first one is named constant bit rate algorithm with K-shortest paths (CBR_KSP) and the second is called constant bit rate algorithm with auxiliary graph (CBR_AG). As rate requirements must be satisfied, the RSA problem would apparently evolve into a scheduling problem. For ABR requests, we also propose a traffic load control (TLC) module to effectively utilize network resource and perform congestion control. Using both CBR algorithms and TLC module together, the demands with QoS requirements can be more appropriately accommodated.
Fragmentation is a well-known and critical phenomenon in the RSA problem of EONs. Because of the optical paths that has been set up and torn down, after a period of time, spectrum recourses can be more fragmented and may cause the increase of blocking probability (BP). The network control methods we propose in this thesis can achieve spectrum reallocation without network disruption by adjusting a requests scheduling. Thus, blocking performance can be significantly improved. Simulation results show that CBR_AG can achieve better BP in a mid-low traffic load, and with the TLC module, the fragmentation problem can be solved and improve the BP at the same time.

[1] M. Jinno, et al., “Spectrum-efficient and scalable elastic optical path network: architecture, benefits, and enabling technologies,” IEEE Commun. Mag. vol. 47, no. 11, Nov. 2009, pp. 66-73.
[2] M. Jinno, et al., “Distance-adaptive spectrum resource allocation in spectrum-sliced elastic optical path network,” IEEE Commun. Mag. vol. 48, no. 8, Aug. 2010, pp. 138-145.
[3] M. S. Borella, J. P. Jue, D. Banerjee, B. Ramamurthy and B. Mukherjee, "Optical components for WDM lightwave networks," in Proc. IEEE, vol. 85, no. 8, Aug. 1997, pp. 1274-1307
[4] H. Zhang, J. P. Jue, and B. Mukherjee, “A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks,” Opt. Netw. Mag., vol. 1, no. 1, Jan. 2000, pp. 47-60.
[5] ITU-T Rec. G.694.1, “Spectral grids for WDM applications: DWDM frequency grid,” 2006.
[6] B. C. Chatterjee, N. Sarma and E. Oki, “Routing and spectrum allocation in elastic optical networks: a tutorial,” IEEE Commun. Surveys Tuts, vol. 17, no. 3, May 2015, pp. 1776-1800.
[7] K. Christodoulopoulos, I. Tomkos and E.A. Varvarigos, “Elastic bandwidth allocation in flexible OFDM-based optical networks,” IEEE J. Lightwave Technol., vol. 29, no. 9, May 2011, pp. 1354-1366.
[8] X.Wan, N. Hua and X. Zheng, “Dynamic routing and spectrum assignment in spectrum-flexible transparent optical networks,” IEEE J. Opt. Commun. Netw, vol. 4, no. 8, Aug. 2012, pp. 603-613.
[9] L. Yang, H. Nan, X. Zheng, H. Zhang and B. Zhou, “Polynomial-time adaptive routing algorithm based on spectrum scan in dynamic flexible optical networks,” China Communications, vol. 10, no. 4, Apr. 2013, pp.49-58.
[10] C.-F. Hsu, Y.-C. Chang, and S.-C. Sie, “Graph-model-based dynamic routing and spectrum assignment in elastic optical networks,” IEEE J. Opt. Commun. Netw, vol. 8, no. 7, Jul. 2016, pp. 507-520.
[11] N.-F. Huang, T.-L. Liu, and C.-F. Hsu, “QoS supported dynamic traffic scheduling in WDM/TDM networks with arbitrary tuning latencies,” in IEEE GLOBECOM, Nov. 2000, pp. 1308-1312.
[12] C.-F. Hsu, T.-L. Liu, and, N.-F. Huang “Multicast traffic scheduling in single-hop WDM networks with arbitrary tuning latencies,” IEEE Trans. Commun, vol. 52, no.10, Oct. 2004, pp. 1747-1757.
[13] M. Zhang, C. You, H. Jiang, and Z. Zhu, “Dynamic and adaptive bandwidth defragmentation in spectrum-sliced elastic optical networks with time-varying traffic,” IEEE J. Lightwave Technol, Vol. 32, no. 5, Mar. 2014, pp. 1014-1023.
[14] T. Takagi, et al., "Disruption minimized spectrum defragmentation in elastic optical path networks that adopt distance adaptive modulation," in ECOC, 18-22 Sep. 2011, pp. 1-3.
[15] F. Cugini, et al., “Push-pull defragmentation without traffic disruption in flexible grid optical networks,” IEEE J. Lightwave Technol, vol. 31, no. 1, Jan. 2013, pp. 125–133.
[16] R. Proietti, et al., “Rapid and complete hitless defragmentation method using a coherent RX LO with fast wavelength tracking in elastic optical networks”, OSA OE. vol. 20, no. 24, 2012, pp. 26958-26968.
[17] P. Ferguson, G. Huston, “Quality of service: delivering QoS on the internet and in corporate networks”, John Wiley & Sons, Inc., 1998
[18] W. Lu, Z. Zhu, “Dynamic service provisioning of advance reservation requests in elastic optical networks”, IEEE J. Lightwave Technol, vol. 31, no. 10, May. 2013, pp. 1621-1627.
[19] P. A. Fishwick, “SimPack: getting started with simulation programming in C and C++,” Proceedings of the 24th conference on Winter simulation, Dec. 1992, pp. 154-162.
[20] P. Fishwick, SimPack Toolkit [Online]. Available: http://www.cise.ufl.edu/~fishwick/introsim/node8.html.
[21] F. A. Khandaker, et al., “A study of statistical capacity sharing in elastic optical networks”, in IEEE ICC, Jun. 2015, pp. 5216-5221.
[22] F. S. Abkenar, A. G. Rahbar “Study and analysis of routing and spectrum allocation (RSA) and routing, modulation and spectrum allocation (RMSA) algorithms in elastic optical networks (EONs)”, OSN, vol. 23, no. 1, Jan. 2017, pp. 5-39.