隨著網路技術的快速發展，以分散式架構的傳統網路導致網路複雜度上升，同時也使維護的成本增加。為了提升網路應用服務品質，軟體定義網路(Software-Defined Networking, SDN)技術因此被提出，以符合現今網路服務多樣化之需求。目前SDN已具許多成功應用及技術實例，其可程式化的特性，也使得網路虛擬化(Network Virtualization)的概念因應而生。因此本研究將透過SDN控制器所提出之網路虛擬化技術之虛擬租戶網路(Virtual Tenant Network, VTN)，對虛擬租戶網路下的路徑分配與資源調度之機制進行研究，透過軟體自訂義之方式實現流量路徑的分配機制，使各個虛擬租戶網路之傳輸流量妥適分配至實體網路達到路徑資源的有效利用，並在路徑利用率發生過載時透過資源調配機制將路徑中對服務層級協議(Service Level Agreement, SLA)需求較低的虛擬租戶做資源利用之限制，確保虛擬租戶的服務品質，使得整體網路資源能合理且有效的利用。
本研究致力於SDN虛擬租戶網路下的路徑分配與資源調度機制，透過SDN控制器所提供之虛擬租戶網路應用建置多個虛擬租戶網路於實體SDN網路上，並針對不同的虛擬租戶網路進行路徑分配，使各個虛擬租戶網路皆能運行於具快速及效率之路徑上，且對每一條路徑進行效能分析，規劃出有效的網路資源調度方式，使得各個路徑之資源能依據網路情況適當的將資源調度給SLA需求較高之租戶，解決因規劃不完善所造成的瓶頸並確保SLA需求較高租戶之使用權。
本研究提出多虛擬租戶網路下的路徑分配與資源調度機制，並進行相關效能分析。首先，本機制將各虛擬租戶之傳輸流量均勻的分配至各實體路徑上進行運行，針對於各路徑上的資源利用率進行監控於分析。而後，透過資源調度機制分析各路徑的資源利用率，對各路徑上之網路資源進行適當調配，確保SLA需求較高之用戶的網路資源使用權，讓SLA需求高的使用者於任何時間點皆能使用到最佳的網路服務品質。根據研究結果顯示，透過本研究所提出的路徑分配機制將資源配置從分配至單一路徑提升為平均分配至五條路徑，並利用資源調度機制將可使用之頻寬提升10.92%。

With the rapid development of the Internet, the distributed architecture of legacy networks is increasing network complexity and maintenance costs. Traditional networks cannot satisfy the demands of current users. Software Defined Network (SDN) was developed to satisfy the current users’ requirements and to improve the quality of service by in various network applications.
In SDN architecture, network intelligence and network state are logically centralized, and the underlying network infrastructure is abstracted from applications. As a result, SDN provides the benefits of programmability, automation, and network control. It also provides network virtualization, which supports the sharing of bandwidth resources. Therefore, this work concerns routing path planning and resource scheduling in a Virtual Tenant Network, which is an application running on SDN Controller. This work proposes a routing path planning mechanism to assign the VTN resources on a physical network routing path to improve routing path resource utilization. A resource scheduling mechanism that reassigns the VTN resource by reserving the high SLA requirement tenant resource when the routing path utilization exceeds a threshold is also presented. The resource scheduling mechanism guarantees the quality of service in the VTN.
This work analyzes the proposed routing path planning mechanism and resource scheduling mechanism in a VTN. First, the routing path mechanism calculates some variables that must be calculated to make the assignment and assigns the VTN resource to a suitable routing path. After network begins to be used, the monitor module monitors the resources associated with each VTN and each routing path. Second, based on the monitored information, the resource scheduling mechanism analyzes the resource utilization to adjust the routing path to which it is assigned. Based on the results thus obtained, the proposed routing path mechanism improves the routing assignment from a single path to five paths. The resource scheduling mechanism improves bandwidth utilization by 10.92%.

[1] P. Xiao, W. Qu, H. Qi, Z. Li and Y. Xu, “The SDN controller placement problem for WAN,” Proceedings of the International Conference on Communications in China (ICCC), pp.220-224, 2014.
[2] S. Betge-Brezetz, G.-B. Kamga and M. Tazi, “Trust Support for SDN Controllers and Virtualized Network Applications,” Proceedings of the IEEE Conference on Network Softwarization (NetSoft), pp.1-5, 2015.
[3] S. Baik, C. Hwang and Y. Lee, “SDN-based architecture for end-to-end path provisioning in the mixed circuit and packet network environment,” Proceedings of the Asia-Pacific Network Operations and Management Symposium (APNOMS), pp.1-4, 2014.
[4] M. A. S. Santos, B. A. A. Nunes, K. Obraczka, T. Turletti, B. T. de Oliveira and C. B. Margi, “Decentralizing SDN’s Control Plane,” Proceedings of the IEEE 39th Conference on Local Computer Networks (LCN), pp.402-405, 2014.
[5] S. Ortiz, “Software-Defined Networking: On the Verge of a Breakthrough?,” Computer, vol. 46, no. 7, pp.10-12, 2013.
[6] A. Dixit, F. Hao, S. Mukherjee, T. Lakshman and R. Kompella, “Towards an Elastic Distributed SDN Controller,” Proceedings of the ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking, pp.1-6, 2013.
[7] M. Karl, J. Gruen and T. Herfet, “Multimedia Optimized Routing in OpenFlow Networks,” Proceedings of the IEEE International Conference on Networks, pp.11-13, 2013.
[8] S.-Y. Wang, “Comparison of SDN OpenFlow Network Simulator and Emulators: EstiNet vs. Mininet,” Proceedings of the IEEE Symposium on Computers and Communication (ISCC), pp.1-6, 2014.
[9] A. Bianco, V. Krishnamoorthi, N. Li and L. Giraudo, “OpenFlow driven ethernet traffic analysis,” Proceedings of the IEEE International Conference on Communications (ICC), pp.3001-3006, 2014.
[10] A. Malishevskiy, D. Gurkan, L. Dane, R. Narisetty, S. Narayan and S. Bailey, “OpenFlow-based Network Management with Visualization of Managed Elements,” Proceedings of the Third GENI Research and Educational Experiment Workshop (GREE), pp.73-74, 2014.
[11] A. Tootoonchian and Y. Ganjali, “HyperFlow: A Distributed Control Plane for OpenFlow,” Proceedings of the Internet Network Management Conference on Research on Enterprise Networking, pp.3-3, 2010.
[12] Y. Chen, X. Gong, W. Wang and X. Que, “VNMC for Network Virtualization in OpenFlow Network,” Proceedings of IEEE International Conference on Cloud Computing and Intelligent Systems, pp.797-801, 2012.
[13] B. Sonkoly and A. Gulyás, “Integrated OpenFlow Virtualization Framework with Flexible Data, Control and Management Functions,” Proceedings of the IEEE INFOCOM, pp.13-14, 2012.
[14] D. Turull, M. Hidell and P. Sjodin, “LibNetVirt: The Network Virtualization Library,” Proceedings of the IEEE International Conference on Communications, pp.5543-5547, 2012.
[15] D. Turull, M. Hidell and P. Sjodin, “Using libNetVirt to control the virtual network,” Proceedings of the IEEE 1st International Conference on Cloud Networking (CLOUDNET), pp.148-152, 2012.
[16] R. Sherwood, G. Gibb, K. Yap, G. Appenzeller, M. Casado, N. McKeown and G. Parulkar, “FlowVisor: A Network Virtualization Layer,” Technical Report Openflow, 2009.
[17] D. Depaoli, R. Doriguzzi-Corin, M. Gerola, and E. Salvadori, “Demonstrating a Distributed and Version-Agnostic OpenFlow Slicing Mechanism,” Proceedings of the IEEE 1st International Conference on Cloud Networking (CLOUDNET), pp.133-134, 2014.
[18] C. Xiaoyuan, N. Yoshikane, T. Tsuritani and I. Morita, “Heterogeneous multi-domain network virtualization with end-to-end differentiated service provisioning and virtual network organization,” Proceedings of the Optical Fiber Communications Conference and Exhibition (OFC), pp.1-3, 2015.
[19] V. Altukhov, V. Podymov, V. Zakharov, E. Chemeritskiy, “VERMONT - A toolset for checking SDN packet forwarding policies on-line,” Proceedings of the International Science and Technology Conference (Modern Networking Technologies) (MoNeTeC), pp.1-6, 2014.
[20] M. Kim, J. Lee, B. Kim and W. Hong, “Implementation of an OpenFlow Network Virtualization for Multi-Controller Environment,” Proceedings of the International Conference on Advanced Communication Technology, pp.589-592, 2012.
[21] Y.Y. Shin, S.H. Kang, J.Y. Kwak, B.Y. Lee and S. Hyang, “The study on configuration of multi-tenant networks in SDN controller,” Proceedings of the International Conference on Advanced Communication Technology, pp.1223-1226, 2014.
[22] R. Munoz, R. Vilalta, R. Casellas, R.Martínez, T. Szyrkowiec, A. Autenrieth, V. López and D. López, “SDN/NFV orchestration for dynamic deployment of virtual SDN controllers as VNF for multi-tenant optical networks,” Proceedings of the Optical Fiber Communications Conference and Exhibition (OFC), pp.1-3, 2015.
[23] Y.Y. Shin, S.H. Kang, J.Y. Kwak, B.Y. Lee and S.H. Yang, “The study on configuration of multi-tenant networks in SDN controller,” Proceedings of the International Conference on Advanced Communication Technology (ICACT), pp.1223-1226, 2014.
[24] Z. Sheng, Q. Zhuzhong, W. Jie and L. Sanglu, “Leveraging tenant flexibility in resource allocation for virtual networks,” Proceedings of the IEEE International Conference on Computer Communications and Networks, pp.1-8, 2014.
[25] H. Tianlin, R. Chao, T. Yazhe, H. Chengchen, L. Jinming and Z. Peng, “VirtualRack: Bandwidth-aware virtual network allocation for multi-tenant datacenters,” Proceedings of the IEEE International Conference on Communications, pp.3620-3625, 2014.
[26] F. Callegati, W. erroni, C. Contoli and G. Santandrea, “Performance of multi-tenant virtual networks in OpenStack-based cloud infrastructures,” Proceedings of the Globecom Workshops on Hot Topics in Software Defined Networking, pp.81-85, 2014.
[27] M. Fernandez, “Comparing OpenFlow Controller Paradigms Scalability: Reactive and Proactive,” Proceedings of the IEEE International Conference on Advanced Information Networking and Applications, pp.1009-1016, 2013.
[28] M. Shirazipour, W. John, J. Kempf, H. Green and M. Tatipamula, “Realizing Packet-optical Integration with SDN and OpenFlow 1.1 Extensions,” Proceedings of the IEEE International Conference on Communications, pp.10-15, 2011.
[29] A. Furculita, M. Ulinic, A. Rus and V. Dobrota, “Implementation Issues for Modified Dijkstra's and Floyd-Warshall Algorithms in OpenFlow,” Proceedings of the RoEduNet International Conference on Networking in Education and Research, pp.26-28, 2013.
[30] M. Jarschel, S. Oechsner, D. Schlosser, R. Pries, S. Goll and P.T. Gia, “Modeling and Performance Evaluation of an OpenFlow Architecture,” Proceedings of International Teletraffic Congress, pp.1-7, 2011.
[31] Vishnoi, R. Poddar, V. Mann and S. Bhattacharya, “Effective Switch Memory Management in OpenFlow Networks,” Proceedings of the ACM International Conference on Distributed Event-Based Systems, pp.177-188, 2014.