| Summary: | 碩士 === 淡江大學 === 電機工程學系碩士班 === 105 === Best-effort delivery mechanism is no longer fulfilling the needs of growing internet requirements, Internet Engineering Task Force (IETF) therefore announced Quality of Service (QoS) to relieve the intense network. However, those two service insurance methods (IntServ, Diffserv) of QoS are still basing on conventional hop-by-hop routing, which requires massive facilities to fulfill rush hours, but mostly idling on off-peak time. Besides, those improvements cannot specifically match every kind of internet services by various conditions, such as bandwidth, delay and jitter. According to experiments, we know that Streaming services need sufficient bandwidth、low delay、low jitter and low loss rate; Voice services need low delay、low jitter，but Voice service does not need much bandwidth, if it has a dejitter buffer, it can reduce the jitter, but increase the delay; Gaming services need low delay and low jitter, but jitter is the most serious impact on the game experience; data transmission services just need sufficient bandwidth.
The developing SDN is therefore presenting to solve this issue effectively. Under the OpenFlow standard, SDN is a novel networking structure, which is considering as highly efficient, adaptive, and easy to be altered and managed. SDN contains control layer and transmission layer, transmissions are handled by switch and the controller processes the rest of the control progresses, and OpenFlow standard is used for communications between controllers and network devices. Centralized controller management can therefore achieve an effective software control. Sensing the connecting status of switches further to provide efficient routing control i.e. transmitting packages by the best path in the network topology. Among various routing algorithms, Dijkstra’s Shortest Path Algorithm is considering as a simple but very efficient algorithm. This algorithm calculates routing weight from nodes to nodes to build best routing tree and to acquire the routing result quickly.
This work makes a combination of all those conditions and conceptions above, creates alternative routing mechanisms to process different networking services. And by Dijkstra’s Shortest Path Algorithm to calculate proper routing, this work would be therefore achieve the multi-services quality insurance control based on SDN.
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