隨著能夠連接至網際網路的裝置數量持續上升，且透過網際網路提供的服務越來越多元化，網際網路上乘載的流量有著日益增加的趨勢。在現有網路環境中，為了能夠提升網路設備的傳輸速度，網路協定通常是使用硬體的方式實作，且每個廠牌的網路設備設定方式不盡相同，因此網路設備無法在很短的時間內支援最新的網路協定，且網管在維護不同品牌的網路設備時也會有一定的困難度；另一方面，因為網際網路的運作需要遵守網路協定的規範，因此網管人員無法非常彈性的操作網際網路的運作方式。為了解決現有網路環境的問題，史丹佛大學提出軟體定義網路(Software-Defined Networking, SDN)的概念，其主要目標為將現有網路設備中的控制層(Control Plane)與資料層(Data Plane)分離，使用集中化控管(Centralize Control)的方式，透過控制器(Controller)使用標準化的協定向位於資料層的網路設備下達指令，讓網管人員能夠自行定義網路的運作模式。

本論文使用軟體定義網路的概念，提出一個具適應性(Adaptive)的鏈路聚合(Link Aggregation)機制，解決現有網路環境因網路協定的關係，任兩點之間即使有多條路徑可以選擇，通常也只會使用單一路徑傳輸封包，而其他路徑的使用效率不佳的問題。藉由本論文的機制，終端使用者可以在更改部分網路設定(Default Gateway與MTU)的前提下，透過此機制同時使用多條路徑傳輸單一連線產生的封包，提高每條路徑的使用效率，並能夠在路徑發生壅塞時動態調整每條路徑傳輸資料的比例。本機制在OF@TEIN+的環境中實驗，實驗結果顯示此機制能夠在犧牲部分網路傳輸性能的前提之下使用多條路徑傳輸封包，並可在觀察到路徑發生壅塞時動態調整每條路徑的傳輸比例。

As the devices connect to the Internet and the service on the Internet getting more and more, there is a trend that the amount of the flow on the Internet is increasing. Therefore, network protocols in legacy network device are usually implemented with hardware to ensure the performance. Due to most of the network devices are implemented with hardware, network operators are not able to operate the network resiliently, and it also takes a long time to implement a new network function. To break through the limitations, Software-Defined Networking decuples the control plane and data plane in legacy network, using a centralized management method to control the network devices.

This thesis proposed an adaptive link aggregation mechanism in hybrid software-defined networking environment to solve the problem that usually only one of the links or paths is used to transmit the packet in legacy network. In the proposed mechanism, the user only needs to modify the default gateway and MTU, directs the packet to the edge router, then the edge router will try to use multiple paths to transmit the data according to the one-way latency and packet loss rate of each path. The proposed mechanism is tested in OF@TEIN+ environment, the results show that the mechanism can use multiple paths to transmit the data with some performance degradation, and dynamically adjust the transmission ratio according to the packet loss rate of each path.

[1] B. Leiner, V. Cerf, D. Clark, R. Kahn, L. Kleinrock, D. Lynch, J. Postel, L. Roberts and S. Wolff, "A brief history of the internet", ACM SIGCOMM Computer Communication Review, vol. 39, no. 5, p. 22, 2009.
[2] V. Cerf and R. Kahn, "A Protocol for Packet Network Intercommunication", IEEE Transactions on Communications, vol. 22, no. 5, pp. 637-648, 1974.
[3] "Hypertext Transfer Protocol -- HTTP/1.1", W3.org. [Online]. Available: https://www.w3.org/Protocols/rfc2616/rfc2616.html. [Accessed: 16- Jul- 2018].
[4] Mishra, Fundamentals of cellular network planning and optimization. Chichester: Wiley, 2004.
[5] D. Law, D. Dove, J. D'Ambrosia, M. Hajduczenia, M. Laubach and S. Carlson, "Evolution of ethernet standards in the IEEE 802.3 working group", IEEE Communications Magazine, vol. 51, no. 8, pp. 88-96, 2013.
[6] J. Kim and I. Lee, "802.11 WLAN: history and new enabling MIMO techniques for next generation standards", IEEE Communications Magazine, vol. 53, no. 3, pp. 134-140, 2015.
[7] R. Perlman, "An algorithm for distributed computation of a spanningtree in an extended LAN", ACM SIGCOMM Computer Communication Review, vol. 15, no. 4, pp. 44-53, 1985.
[8] B. Nunes, M. Mendonca, X. Nguyen, K. Obraczka and T. Turletti, "A Survey of Software-Defined Networking: Past, Present, and Future of Programmable Networks", IEEE Communications Surveys & Tutorials, vol. 16, no. 3, pp. 1617-1634, 2014.
[9] N. Feamster, J. Rexford and E. Zegura, "The road to SDN", ACM SIGCOMM Computer Communication Review, vol. 44, no. 2, pp. 87-98, 2014.
[10] S. Vissicchio, L. Vanbever and O. Bonaventure, "Opportunities and research challenges of hybrid software defined networks", ACM SIGCOMM Computer Communication Review, vol. 44, no. 2, pp. 70-75, 2014.
[11] "Use Multipath TCP to create backup connections for iOS", Apple Support. [Online]. Available: https://support.apple.com/en-us/HT201373. [Accessed: 16- Jul- 2018] .
[12] C. Paasch and O. Bonaventure, "Multipath TCP", Communications of the ACM, vol. 57, no. 4, pp. 51-57, 2014.
[13] M. Scharf and A. Ford, "Multipath TCP (MPTCP) Application Interface Considerations", 2013.
[14] Abley, K. Lindqvist, E. Davies, B. Black and V. Gill, "IPv4 Multihoming Practices and Limitations", 2005.
[15] "臺灣學術網路環境介紹". [Online]. Available: http://depart.moe.edu.tw/ED2700/News.aspx?n=697CD84F427DE922&sms=954B3E2521E9F948. [Accessed: 16- Jul- 2018].
[16] " HiNet寬頻上網". [Online]. Available: http://broadband.hinet.net/. [Accessed: 16- Jul- 2018].
[17] "RFC 7348 - Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks", Datatracker.ietf.org. [Online]. Available: https://datatracker.ietf.org/doc/rfc7348/?include_text=1. [Accessed: 16- Jul- 2018].
[18] "Open vSwitch", Openvswitch.org. [Online]. Available: https://www.openvswitch.org/. [Accessed: 16- Jul- 2018].
[19] R. Fielding, Architectural styles and the design of network-based software architectures. 2000.
[20] L. Dong, R. Gopal and J. Halpern, "Forwarding and Control Element Separation (ForCES) Protocol Specification", 2010.
[21] N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker and J. Turner, "OpenFlow", ACM SIGCOMM Computer Communication Review, vol. 38, no. 2, p. 69, 2008.
[22] R. Khondoker, A. Zaalouk, R. Marx and K. Bayarou, "Feature-based comparison and selection of Software Defined Networking (SDN) controllers", 2014 World Congress on Computer Applications and Information Systems (WCCAIS), 2014.
[23] "Ryu SDN Framework", Osrg.github.io. [Online]. Available: https://osrg.github.io/ryu/. [Accessed: 16- Jul- 2018].
[24] "Floodlight OpenFlow Controller -", Project Floodlight. [Online]. Available: http://www.projectfloodlight.org/floodlight/. [Accessed: 16- Jul- 2018].
[25] J. Medved, R. Varga, A. Tkacik and K. Gray, "OpenDaylight: Towards a Model-Driven SDN Controller architecture", Proceeding of IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks 2014, 2014.
[26] P. Berde, W. Snow, G. Parulkar, M. Gerola, J. Hart, Y. Higuchi, M. Kobayashi, T. Koide, B. Lantz, B. O'Connor and P. Radoslavov, "ONOS", Proceedings of the third workshop on Hot topics in software defined networking - HotSDN '14, 2014.
[27] "Cherry". [Online]. Available: https://github.com/superkkt/cherry/. [Accessed: 16- Jul- 2018].
[28] "Faucet". [Online]. Available: https://github.com/faucetsdn/faucet. [Accessed: 16- Jul- 2018].
[29] D. Beazley, "Understanding the Python GIL". [Online]. Available: http://www.dabeaz.com/python/UnderstandingGIL.pdf. [Accessed: 16- Jul- 2018].
[30] "Open Networking Foundation". [Online]. Available: https://www.opennetworking.org/about. [Accessed: 16- Jul- 2018].
[31] "OpenFlow Specification 1.0". [Online]. Available: https://3vf60mmveq1g8vzn48q2o71a-wpengine.netdna-ssl.com/wp-content/uploads/2013/04/openflow-spec-v1.0.0.pdf. [Accessed: 16- Jul- 2018].
[32] "OpenFlow Specification 1.5.1". [Online]. Available: https://3vf60mmveq1g8vzn48q2o71a-wpengine.netdna-ssl.com/wp-content/uploads/2014/10/openflow-switch-v1.5.1.pdf. [Accessed: 16- Jul- 2018].
[33] "OpenFlow Specification 1.3.5". [Online]. Available: https://3vf60mmveq1g8vzn48q2o71a-wpengine.netdna-ssl.com/wp-content/uploads/2014/10/openflow-switch-v1.3.5.pdf. [Accessed: 16- Jul- 2018].
[34] "OpenFlow Specification 1.1.0". [Online]. Available: https://3vf60mmveq1g8vzn48q2o71a-wpengine.netdna-ssl.com/wp-content/uploads/2014/10/openflow-spec-v1.1.0.pdf. [Accessed: 16- Jul- 2018].
[35] D. Scholz, "A Look at Intel’s Dataplane Development Kit", Network Architectures and Services, pp. 115-122, 2014.
[36] "IEEE 802.1 P,Q - QoS on the MAC level". [Online]. Available: http://www.cse.hut.fi/fi/opinnot/T-110.5190/1999/papers/08IEEE802.1QosInMAC/qos.html. [Accessed: 16- Jul- 2018].
[37] K. Clark and K. Hamilton, Cisco LAN switching. Indianapolis, IN, USA: Cisco Press, 1999.
[38] S. Sharma, K. Gopalan, S. Nanda and T. Chiueh, "Viking: a multi-spanning-tree Ethernet architecture for metropolitan area and cluster networks", IEEE INFOCOM 2004.
[39] J. Touch and R. Perlman, "Transparent Interconnection of Lots of Links (TRILL): Problem and Applicability Statement", 2009.
[40] C. Hopps, "Analysis of an Equal-Cost Multi-Path Algorithm", 2000.
[41] J. Zhou, M. Tewari, M. Zhu, A. Kabbani, L. Poutievski, A. Singh and A. Vahdat, "WCMP", Proceedings of the Ninth European Conference on Computer Systems - EuroSys '14, 2014.
[42] S. Kandula, D. Katabi, S. Sinha and A. Berger, "Dynamic load balancing without packet reordering", ACM SIGCOMM Computer Communication Review, vol. 37, no. 2, p. 51, 2007.
[43] A. Ford, C. Raiciu, M. Handley and O. Bonaventure, "TCP Extensions for Multipath Operation with Multiple Addresses", 2013.
[44] Y. Yuan, Z. Zhang, J. Li, J. Shi, J. Zhou, G. Fang and E. Dutkiewicz, "Extension of SCTP for Concurrent Multi-Path Transfer with Parallel Subflows", 2010 IEEE Wireless Communication and Networking Conference, 2010.
[45] S. Fang, Y. Yu, C. Foh and K. Aung, "A Loss-Free Multipathing Solution for Data Center Network Using Software-Defined Networking Approach", IEEE Transactions on Magnetics, vol. 49, no. 6, pp. 2723-2730, 2013.
[46] T. Subedi, K. Nguyen and M. Cheriet, "OpenFlow-based in-network Layer-2 adaptive multipath aggregation in data centers", Computer Communications, vol. 61, pp. 58-69, 2015.
[47] D. Banfi, O. Mehani, G. Jourjon, L. Schwaighofer and R. Holz, "Endpoint-Transparent Multipath Transport with Software-Defined Networks", 2016 IEEE 41st Conference on Local Computer Networks (LCN), 2016.
[48] E. Vanini, R. Pan, M. Alizadeh, P. Taheri and T. Edsall, "Let It Flow: Resilient Asymmetric Load Balancing with Flowlet Switching.", 14th USENIX Symposium on Networked Systems Design and Implement, pp. 407-420, 2017.
[49] R. Prosad, C. Davrolis, M. Murray and K. Claffy, "Bandwidth estimation: metrics, measurement techniques, and tools", IEEE Network, vol. 17, no. 6, pp. 27-35, 2003.
[50] N. Hu and P. Steenkiste, "Evaluation and characterization of available bandwidth probing techniques", IEEE Journal on Selected Areas in Communications, vol. 21, no. 6, pp. 879-894, 2003.
[51] C. Guerrero and M. Labrador, "On the applicability of available bandwidth estimation techniques and tools", Computer Communications, vol. 33, no. 1, pp. 11-22, 2010.
[52] E. Goldoni and M. Schivi, "End-to-End Available Bandwidth Estimation Tools, An Experimental Comparison", Traffic Monitoring and Analysis, pp. 171-182, 2010.
[53] "One-Way Ping (OWAMP)". [Online]. Available: http://software.internet2.edu/owamp/index.html. [Accessed: 16- Jul- 2018].
[54] "RFC 1305 - Network Time Protocol (Version 3) Specification, Implementation and Analysis". [Online]. Available: https://datatracker.ietf.org/doc/rfc1305/. [Accessed: 16- Jul- 2018].
[55] J. Hartigan and M. Wong, "Algorithm AS 136: A K-Means Clustering Algorithm", Applied Statistics, vol. 28, no. 1, p. 100, 1979.
[56] M. Katevenis, S. Sidiropoulos and C. Courcoubetis, "Weighted round-robin cell multiplexing in a general-purpose ATM switch chip", IEEE Journal on Selected Areas in Communications, vol. 9, no. 8, pp. 1265-1279, 1991.
[57] G. Miao, Fundamentals of mobile data networks. New York: Cambridge University Press, 2016.
[58] "OF@TEIN+". [Online]. Available: https://github.com/OFTEIN-NET/OFTEIN-Plus. [Accessed: 16- Jul- 2018].
[59] "Asi@Connect". [Online]. Available: http://www.tein.asia/main/?mc=0. [Accessed: 16- Jul- 2018].
[60] "Plotly". [Online]. Available: https://plot.ly/javascript/. [Accessed: 16- Jul- 2018]
[61] S. Ha, I. Rhee and L. Xu, "CUBIC", ACM SIGOPS Operating Systems Review, vol. 42, no. 5, pp. 64-74, 2008.
[62] N. Cardwell, Y. Cheng, C. Gunn, S. Yeganeh and Van Jacobson, "BBR", Communications of the ACM, vol. 60, no. 2, pp. 58-66, 2017.