Research On SDN-based Traffic Scheduling Strategy For Data Center Network

Since Equal-Cost Multi-Path(ECMP)may cause the network to be partly congested and lead to insufficient utilization of network resources,traffic scheduling strategies basing on Software-Defined Networking(SDN)are introduced into Data Center Networks(DCN).However,there are intrinsic defects in SDN as well.How to keep off from the defects and make good use of SDN in traffic scheduling becomes an urgent task for DCN.The thesis takes this as the starting point and proposes two such traffic scheduling strategies,named BFlows which bases on the number of elephant flows and the load of link and EFattree which bases on the type of the service.The main content is as follows:1.The SDN controller usually computes the best path for the traffic basing on the load information of link that it has acquired from the switches.However,the instantaneous load of link can not reflect the loading condition of that link under specific state exactly because it is fluctuating all the time.As a result,the computed path may be nonoptimal.To solve this problem,BFlows firstly picks out a number of shortest paths from all the feasible paths between the source and destination hosts,and then picks out several ones which are carrying least elephant flows,and find out the lightest-loaded one from these candidate paths at last.The outcome of the simulation experiment denotes that,comparing to ECMP,Hedera and PureSDN,BFlows gains 8.82%,4.37% and 1.22% promotions respectively at network throughput,12.86%,-1.86% and-0.92% promotions respectively at link utilization,and 17.93%,0.57% and 0.40% promotions respectively at link bandwidth utilization.2.In traffic scheduling strategies which perform blended treatment for delay-sensitive and bandwidth-sensitive traffic,both the performance requirements for the network of delay-sensitive and bandwidth-sensitive services can not be met because of the mutual interference between the two types of traffic.To solve this problem,EFattree separates the network into two parts so as to isolate the transmission of delay-sensitive and bandwidth-sensitive traffic.What's more,it handles delay-sensitive traffic rapidly with ECMP and deals with bandwidth-sensitive traffic with SDN.The outcome of the simulation experiment denotes that,comparing to ECMP,Hedera and PureSDN,EFattree suffers 1.68%,2.50% and 3.05% losses respectively at network throughput due to making use of only half of the network resources to transmit most of the traffic of the network,but gains 97.16%,95.87% and 92.82% reductions respectively at average first-packet round-trip delay of delay-sensitive traffic,96.65%,94.85% and 68.54% reductions respectively at average round-trip delay of delay-sensitive traffic,97.47%,96.95% and 86.92% reductions respectively at mean deviation of round-trip delay of delay-sensitive traffic,and it achieves loss-free transmission for delay-sensitive traffic.