Architecture And Joint Scheduling Of Hybrid Optical/Electrical Switch For Data Centers

The rise of innovative applications and services like cloud computing,social networks and multimedia streaming have significantly boosted the internet traffic,data centers are about to experience a huge evolution.Current data center networks(DCNs)typically deploy a multilayer,hierarchical,FatTree topology based on commodity electrical switches.These electrical switches suffer from bandwidth bottlenecks because of the inability to increase the pin density of electrical integrated circuits;meanwhile,they also introduce high power consumption and huge latency due to the optical-electrical-optical(O/E/O)conversions and electronic switch fabrics.More efficient schemes are required that can provide high throughput,low latency and reduced power consumption.Optical switching networks have been considered as a promising solution.Optical switching can offer higher communication bandwidth by exploiting the high capacity of wavelength division multiplexing(WDM).In the meantime,it does not require heavy O/E/O conversions,hence keeping the power consumption at a significantly lower level.It also brings other merits like data rate/format transparency.However,in practical implement,both Optical Circuit Switching(OCS)and Optical Packet Switching(OPS)have encountered several difficulties and challenges.The slow reconfiguration time of OCS lead to the incapability of handle dynamic,bursty traffic streams,cause low flexibility and average utilization.Although OPS is able to realize flexible and fast switching,the required optics and photonic technologies are not yet mature enough to support the deployment of a commercial use optical packet switch.Based on the previous researches of optical switching in data center,this thesis fully combined the advantages of optical and electrical,proposed a hybrid switching architecture which optical and electrical parts are organized in a creative cascaded manner.Different from the paralleled EPS/OCS hybrid scheme which employ both electrical and optical switches in core layer,ECHOES core layer switches are all optical switches,although edge layer keeps using electrical switches.ECHOES core optical switches and edge electrical switches are combined together by information interactions.ECHOES adopt a joint scheduling scheme,utilized centralized control of the network traffics,to provide a good contention resolution performance.To be specific,the main works of this thesis are introduced as follows:1.Systematically described the component and principle of ECHOES architecture.Electrical edge buffer are used to buffer and aggregate the data from servers,then its virtual output queue(VOQ)information are transmitted to optical core switches,and calculated by a high efficiency frame-based scheduling algorithm to get the proper scheduling scheme,in this way the contention problem can be solved.2.Simulation experiments were employed to evaluate the performance of ECHOES architecture,on delay,throughput and scalability.Simulation indicates ECHOES can work well under both uniform traffic and nonuniform traffic,ECHOES can support a workload up to 0.93 while still guarantee near 100% throughput and stable delay in microseconds.Simulation also suggested the adopted scheduling algorithm has good scalability.3.Combine the load feature of data center,the delay of ECHOES architecture has been analyzed and optimized.The analysis showed the delay performance of ECHOES can be optimized to a large extent,by adjusting the frame size of the adopted scheduling algorithm.Meanwhile,the bursty high load traffic need to be carefully deal with,then a good optimized delay can be found through simulation.