在現今廣泛的網路應用中 (如:智慧電網、雲端、智慧工廠)，要達成高可靠、低延遲的通訊技術變的非常重要。軟體定義網路及網路功能虛擬化這兩項新興的技術就可以打破傳統網路架構的限制，進而符合現今使用者的需求。SDN能將控制層的功能集中到單一控制器當中，即可根據蒐集到的網路資訊作彈性的控制。NFV則能夠將網路資源虛擬化，可使得管理者方便的作資源管理，進而節省花費。然而這些技術都有一些瓶頸。首先在SDN技術中，傳統的SDN鏈結回復機制速度太慢，而其他研究雖提出較快的方法但卻犧牲了交換器的記憶體使用量。而第二個瓶頸是當網路管理者採用NFV技術時，需要找到一個有效的資源規劃方法，衍生出”虛擬網路鑲嵌”的問題需要解決，然而現今提出的方法都還不是最有效的。首先，就第一個瓶頸，我們提出一個基於”分段路由”技術的鏈結回復機制，能夠達成快速的鏈結回復且只占用少數的交換器記憶體。在第二個瓶頸中，我們提出一個有效的網路規畫方法，不僅使用考慮全域資源的評分方式，還使用基因演算法來分配路徑分割的比率及路徑。我們也使用判定鏈結花費的函數來評估整體網路的效能，最後的結果也證明了我們的方法能夠達到最小的鏈結花費。

It is crucial to achieve high reliability and low latency concurrently for networked applications such as smart grid, data center, and intellengent factory. Software-Defined Networking (SDN) and Network Function Virtualization (NFV) are two novel network technologies that are proposed to break the obstacle of network architecture. SDN put the control plane to a central controller to control network traffic flexibly. NFV virtualize the traditional network function machine into software which installed in the specific machine and could plan network resource flexibly and dynamically. However, they has some bottlenecks. Firstly, in SDN, traditional link recovery mechanism will cost much time and the other faster mechanisms will occupy too many memories in switches. Therefore, to find a fast mechanism with low memory cost is very difficult. Second, in NFV, how to allocate virtualized resources to end users is also a difficult problem. Consequently, Many researches has proposed some algorithms to solve Virtual Network Embedding (VNE) problem. Nevertheless, the efficient algorithm to solve VNE problem is still not proposed. In our thesis, for the first bottleneck, we present a link recovery mechanism which enhances the reliability of the network, maintains low communication latency, and reduces memory utilizations of the switching devices by introducing Segment Routing. The results of our link recovery mechanism could achieve low recovery time and low memory utilization. In the second bottleneck, we propose an efficient VNE algorithm which uses node-rankng approach with global resources and adopts genetic algorithm path splitting method. We also use the link cost function to evaluate the network performance, and the results shows that our VNE algorithm outperforms other works.

[1] J J. Andrews, S. Buzzi, W. Choi, S. Hanly, A. Lonazo, A. Ksoong, J. Zhang, “What will 5G be?,” in Proc. IEEE J. Sel. Areas Commun., vol. 32, no. 6, pp. 1065- 1082, Jun. 2014.
[2] B. Holfeld, D. Wieruch, T. Wirth, L. Thiele, S. A. Ashraf, J. Huschke, I. Aktas, and J. Ansari, “Wireless communication for factory automation: an opportunity for lte and 5g systems,” IEEE Commun. Mag., vol. 54, no. 6, June. 2016, pp. 36–43.
[3] S. Bhardwaj, L. Jain, and S. Jain, “Cloud computing: A study of infrastructure as a service (IaaS),” Int. J. Eng. Inf. Technol., vol. 2, pp. 60–63, Jan. 2010.
[4] N. McKeown, “Software-defined networking,” INFOCOM Keynote Talk, vol. 17, no. 2, 2009, pp. 30–32.
[5] J. G. Herrera and J. F. Botero, “Resource allocation in NFV: A comprehensive survey,” IEEE Trans. Netw. Service Manage., vol. 13, no. 3, pp. 518–532, Sep. 2016.
[6] N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner, “OpenFlow: Enabling innovation in campus networks,” in Proc. ACM SIGCOMM Comput. Commun. Rev., vol. 38, no. 2, Mar. 2008, pp. 69–74.
[7] R. Muñoz et al., “Integrated SDN/NFV management and orchestration architecture for dynamic deployment of virtual SDN control instances for virtual tenant networks [invited],” IEEE/OSA J. Opt. Commun. Netw., vol. 7, no. 11, pp. B62–B70, Nov. 2015.
[8] X. Costa-Perez et al., “5G-crosshaul: An SDN/NFV integrated fronthaul/backhaul transport network architecture,” IEEE Wireless Commun., vol. 24, no. 1, pp. 38–45, Feb. 2017.
[9] E. Fadel et al., “A survey on wireless sensor networks for smart grid,” Comput. Commun., vol. 71, no. 1, Nov. 2015, pp. 22–33
[10] D. Turner, K. Levchenko, A. C. Snoeren, and S. Savage, “California fault lines: Understanding the causes and impact of network failures,” in Proc. ACM SIGCOMM Comput. Commun. Rev, vol. 40, no. 4, Jan. 2010, pp. 315–326.
[11] M. Goyal, K. K. Ramakrishnan, and W.-C. Feng, “Achieving faster failure detection in OSPF networks,” in Proc. IEEE Int. Conf. Commum. (ICC), vol. 1, May 2003, pp. 296–300.
[12] P. Thorat, S. M. Raza, D. T. Nguyen, G. Im, H. Choo, and D. S. Kim, “Optimized self-healing framework for software defined networks,” in Proc. ACM Int. Conf. on Ubiquitous Information Management and Commun. (IMCOM), Jan. 2015, pp. 1-6.
[13] Y. D. Lin et al., “Fast failover and switchover for link failures and congestion in software defined networks,” in Proc. IEEE Int. Conf. Commun. (ICC), May 2016, pp. 1–6.
[14] D. Staessens, S. Sharma, D. Colle, M. Pickavet, and P. Demeester, “Software defined networking: Meeting carrier grade requirements,” in Proc. 18th Workshop Local Metropol. Area Netw. (LANMAN), 2011, pp. 1–6.
[15] A. Sgambelluri, A. Giorgetti, F. Cugini, F. Paolucci, and P. Castoldi, “Openflow-based segment protection in ethernet networks,” Journal of Optical Commun. and Netw. (JOCN), vol. 5, no. 9, pp. 1066–1075, 2013.
[16] S. Sharma, D. Staessens, D. Colle, M. Pickavet, and P. Demeester, “OpenFlow: Meeting carrier-grade recovery requirements,” Comput. Commun., vol. 36, no. 6, Mar. 2013, pp. 656–665.
[17] Alessio Giorgetti, Andrea Sgambelluri, Francesco Paolucci, Piero Castoldi, “Reliable segment routing,” in Proc. 7th Int. Workshop Rel. Netw. Design Model. (RNDM), 2015, pp. 181–185.
[18] Huang Liaoruo, Shen Qingguo, Shao Wenjuan, “A Source Routing Based Link Protection Method for Link Failure in SDN,” in Proc. IEEE Int. Conf. on Comput. and Commun. (ICCC), Oct. 2017, pp. 1–6.
[19] M. Al-fares, A. Loukissas, and A. Vahdat, “A scalable, commodity data center network architecture,” in Proc. ACM SIGCOMM Comput. Commun. Rev., vol. 38, no. 4, 2008, pp. 63–74.
[20] C.-X. Wang et al., ‘‘Cellular architecture and key technologies for 5G wireless communication networks,’’ in Proc. IEEE Commun. Mag., vol. 52, no. 2, pp. 122–130, Feb. 2014.
[21] N. M. M. K. Chowdhury and R. Boutaba, “A survey of network virtualization,” Comput. Netw., vol. 54, no. 5, pp. 862–876, 2010.
[22] N. Chowdhury, M. Rahman, and R. Boutaba, “Virtual network embedding with coordinated node and link mapping,” in Proc. IEEE INFOCOM 2009, pp. 783–791, Apr. 2009
[23] M. Yu, Y. Yi, J. Rexford, and M. Chiang, “Rethinking virtual network embedding: Substrate support for path splitting and migration,” ACM SIGCOMM Computer Communication Review, vol. 38, no. 2, pp. 17– 29, April. 2008.
[24] N. M. K. Chowdhury and R. Boutaba, “Network virtualization: State of the art and research challenges,” IEEE Commun. Mag., vol. 47, no. 7, pp. 20–26, Jul. 2009.
[25] A. Fischer, J. Botero, M. Till Beck, H. de Meer, and X. Hesselbach, “Virtual network embedding: A survey,” in Proc. IEEE Commun. Surveys Tuts., vol. 15, no. 4, pp. 1888–1906, 4th 2013.
[26] X. Cheng, S. Su, Z. Zhang, K. Shuang, F. Yang, Y. Luo and J. Wang, “Virtual network embedding through topology awareness and optimization,” Computer Networks, vol. 56, no. 6, pp. 1797-1813, Jun. 2012.
[27] H. Cao, L. Yang, H. Zhu, “Novel node-ranking approach and multiple topology attributes-based embedding algorithm for single-domain virtual network embedding,” in Proc. IEEE Internet Things J., vol. 5, no. 1, pp. 108-120, 2018.
[28] M. M. A. Khan, N. Shahriar, R. Ahmed, and R. Boutaba, “Multi-path link embedding for survivability in virtual networks,” in Proc. IEEE Trans. Netw. Service Manag., vol. 13, no. 2, pp. 253–266, Jun. 2016.
[29] M. Ericsson, M. G. C Resende, and P. M. Pardalos, “A genetic algorithm for the weight setting problem in OSPF routing,” J. Combinatorial Optimization, 2002.