بررسي رفتار متقابل بين روش هاي زمان بندي و جريان هاي ترافيكي هجومي

چكيده انگليسي :

The Study of Interaction between Scheduling Algorithms and Bursty Traffic Mahmoud Daneshvar Farzanegan m daneshvar@ec iut ac ir July 6th 0f 2013 Department of Electrical and Computer Engineering Isfahan University of Technology 84156 83111 Isfahan IranSupervisor Prof Hossein Saidi hsaidi@cc iut ac irAdvisor Prof Mehdi Mahdavi m mahdavi@cc iut ac ir Isfahan University of TechnologyAbstract The provisioning of Quality of Service QoS is one of the most important challenges in theinvestigations over the networking science era Scheduling algorithms which determine how packets selectfor servicing highly affect on the performance of networks especially in providing QoS However thenature of Internet traffic especially real time multimedia applications is bursty and one way to control theQoS is reduction of the burstiness of the arrival flows by traffic shapers As a result the fairness indexmainly considers this smoothed traffic and the service rate as the main parameter to differentiate amongdifferent sessions flows However due to increasing delay in shapers the server cannot provide anacceptable QoS to some bursty and delay sensitive traffic flows such as real time video IPTV Therefore when the QoS of the bursty traffic should be provided some other parameters should be involved A main idea in this dissertation is that besides the arrival rate sessions are isolated by the burstiness ofthe arrival traffic and the scheduling algorithm attempt to differentiate sessions according to service rate andburst service Due to assess the performance of a scheduler under bursty traffic flows a new schedulingframework including a new index for evaluating burst service is presented in this study Then this study introduces and evaluates a new fluid flow scheduling algorithm RBSS that not onlyuses arrival rates but also considers burstiness of the arrival traffic flows RBSS enhances the GeneralizedProcessor Sharing GPS algorithm which is the best algorithm in term of service fair index SFI In the following of the study a packet scheduling algorithm BSCFQ which attempts to provide abalance between bursty and non bursty smooth traffic flows is introduced BSCFQ is an improvement of awell known packet scheduling algorithm which is called Self Clock Fair Queueing SCFQ In thepresented algorithm BSCFQ the capability of the SCFQ is increased to compensate a limited value of themissed or postponed service for each session BSCFQ is also evaluated by calculating the fairness index delay bound and the new criterion which has been defined in the framework Improvement of the SCFQdoes not necessitate any additional computation as regards the implement algorithm The relation between the scheduling algorithms and bursty traffic has been studied in another viewpoint The scheduling algorithms may increase the burstiness of the arrival traffic flows Some study is proposedto smooth the output traffic flows in the scheduler A review on the Round Robin family schedulingalgorithm has been done and a new scheduling algorithm GDB DRR in this family is presented InGDB DRR at first a group of sessions is selected by a smooth scheduling algorithm called DB WFQ thena session is chosen by DRR algorithm The simulation results indicate that the reduction of burstiness inDB WFQ is similar to one of the smooth output scheduling algorithm called SRR The advantage ofGDB DRR vs SRR is its lower complexity and its capability to support the scheduling of variable lengthpacket As a result in this study the interaction between scheduling algorithm is considered At first the effectof bursty traffic on scheduling algorithm is evaluated Then the effect of scheduling algorithm on burstinessof a flow is studied According to this viewpoint three new scheduling algorithms have been proposed Keywords Quality of Service Scheduling Algorithm Bursty Traffic Network Calculus

دانشور فرزانگان، محمود

بررسي رفتار متقابل بين روش هاي زمان بندي و جريان هاي ترافيكي هجومي

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