Research On Software Defined Electrical And Optical Hybrid Data Center Network

In recent years,data centers have been rapidly evolving as the core infrastructure for a host of new types of computing and applications,such as cloud computing and big data.Changes in communications patterns presents new challenges for data center networks that connect large-scale servers and storage devices.The traditional electrical switching network faces the problems of limited network bandwidth and excessive energy consumption,which is difficult to meet the needs of large-scale data center networks.Optical and electrical hybrid data center network combines the advantages of optical switching and electrical switching,and dynamically adjusts the network topology and bandwidth as required to effectively improve the performance of the network and reduce the power consumption and routing complexity of the network.Aiming at the problems of scalability and performance of current optical switching network architecture,low utilization rate of multicast resources,and shortcomings of link scheduling,this dissertation focuses on novel optical switching network architecture,efficient multicast optimization mechanism and link scheduling mechanism with priority,the main work of this dissertation includes:(1)To overcome the shortcomings of scalability,flexibility and performance of current optical switching networks,this dissertation proposes a scalable and high performance optical switching fabric named DETOUR.DETOUR is designed as a distributed optical switching network architecture that connects optical switches in a 2D-Torus topology,effectively increasing the size of optical switching networks and supporting dynamic network expansion.DETOUR is based on the “broadcast-select”optical switching mechanism that provides flexible support for multiple communication modes such as unicast,multicast,and broadcast.DETOUR designs an optical switch that supports exchange signals in the optical domain in two dimensions.The optical signals from any soruce switch can be to any any optical switch in DETOUR to support the direct optical link between any optical switches.According to the property of DETOUR,a recursive conflict wavelength adjustment algorithm is proposed,and the non-blocking characteristics of DETOUR are proved theoretically.Compared to other optical switching networks,DETOUR meets both scalability,flexibility and high performance requirements.Experiments have shown that DETOUR can reduce average flow completion times of about 34% and 57%,as well as about 21% and 30% energy consumption,compared to OvS and Jellyfish.(2)To overcome the low resource utilization of current multicast optimization schemes and can not be extended to large-scale optical and electrical hybrid networks,a collaborative optimization mechanism iCAST of physical layer split multicast and packet replication electrical multicast is proposed.iCAST oriented application layer aware multicast demand,proposed a greedy multicast tree construction algorithm and flexible multicast flow switching strategy.During the construction of a multicast tree,iCAST preferentially allocates optical multicast links to the high-traffic multicast groups,and if not,it looks for available electrical multicast.During configuration after building the multicast tree,iCAST uses a flexible routing policy to switch multicast traffic between the electrical switching network and the optical switching network,thereby avoiding blocking multicast flows for optical link resources.The optical and electrical hybrid multicast prototyping system was built with free-space optics and optical beamsplitters and the highperformance computing framework MPICH was redesigned to support iCAST.Experiments show that iCAST reduces the completion time by an order of magnitude compared to the existing ring algorithms in MPICH.(3)To overcome the shortcomings in reducing Flow Completion Time(FCT),especially the FCT of small flows,a flow scheduling and optical link scheduling joint optimization mechanism,HyFabric is proposed.HyFabric adopots the strategy of Shortest Remaining Processing Time(SRPT)to optimize the average FCT.To support the SRPT strategy,HyFabric redesigned queues in the Top of Rack(ToR)switch to dequeue and discard packets based on the SRPT policy.The ToR switch contains virtual output queues that accumulates packets of different destination ToR switches,and the scheduler on the ToR switch forwards pakcets in the optical switching network or electrical switching network.HyFabric proposed a priority-based multi-level stable marriage algorithm to allocate optical links to the packets accumulated in the virtual output queues.The priority is calculated based on the priority information in the accumulated packets.Compared with the current works,HyFabric can effectively combine optical switching and electric switching networks to jointly implement the SRPT strategy and minimize the average FCT.Experiments show that HyFabric reduces the FCT above 93 % and the energy consumption above 32%,compared to ProjecToR and Solstice.