Study On The Hybrid Optical And Electrical Switching Architecture For Intra-data Center Networks

The data centers,which carry the network applications,storage the network data,provide the maintenance environment for network programs,are playing an important role in the global Internet system.Driven by new applications such as cloud computing,social networks,high definition TV,and games on demand,data center traffic has been growing exponentially during the last few years.The intra-data center networks(intra-DCN)that provide interconnection for servers are facing rapid increase in both the scale and the bandwidth requirement.Traditional intra-DCN electrical packet switching architectures will cause many issues in power consumption,cooling systems,and greenhouse gases emission to handle the future data center traffic.As the optical switching technology has relatively high energy efficiency and large bandwidth capacity,researchers have introduced it into data center networks recently and presented the concept of hybrid optical and electrical intra-DCN switching architecture.In hybrid optical and electrical intra-DCN switching architectures,the "elephant" inter-rack traffic requests are transported through optical circuit switching and the "mouse" inter-rack traffic requests are transported through electrical packet switching.Many hybrid optical and electrical intra-DCN switching architectures have been proposed.They try to combine the advantages of both the optical switching and electrical switching.According to a report,the hybrid optical and electrical intra-DCN switching architectures may provide about 75%energy saving.This thesis studies the key technology and important problems in hybrid optical and electrical intra-DCN switching architectures.It concentrates on the issues about electrical packet processing in top-of-rack switch,resource utilization,and the scalability of optical circuit switching architecture.Main contents and contributions of the thesis are introduced as followsStudy the problem of packet processing at inter-rack switches in the electrical domainConcentrating on the problem that inter-rack electrical packet switches have heavy header processing load and large switching table when handling the server-to-server packets in electrical domain:1)We propose to assemble small length server-to-server packets into large length rack-to-rack frames at top-of-rack switches.2)We prove that there is a trade-off between traffic packet loss rate and system fairness in top-of-rack switches when handling the non-uniformly distributed inter-rack traffic which is transported in electrical domain.3)Based on the trade-off,we proposed an assembly and scheduling algorithm for top-of-rack switches that can balance the system fairness and packet loss rate.Study the problem of spectrum utilization and wire complexity in intra-DCN optical circuit switching architectureConcentrating on the problem that the intra-DCN optical circuit switching architecture may have low spectrum utilization when handling optical inter-rack traffic requests with uneven bandwidth requirement and may have high wire complexity when the racks are placed far apart:1)We propose an intra-DCN optical circuit switching architecture that is called the elastic ring with FS-ROADMs.2)We investigate the spectrum allocation problem in elastic ring with FS-ROADMs and propose an integer linear program formulation as well as a greedy heuristic algorithm to solve the spectrum allocation problem.3)We investigate the performance of elastic ring with FS-ROADMs and discuss its feasibility.Study the problem of scalability in intra-DCN optical circuit switching architectureConcentrating on the problem that maximum number of supported top-of-rack switches in elastic ring with FS-ROADMs is limited by the total spectrum resource in the ring fiber:1)We propose a multi-ring based intra-DCN optical circuit switching architecture.It can provide non-blocking connectivity for more than 104 top-of-rack switches.2)We investigate the routing and spectrum allocation problem in the architecture and present two spectrum allocation schemes,the fixed scheme and the elastic scheme.3)For both of the two spectrum allocation schemes,we give method to solve the routing and spectrum allocation problem.4)We discuss and compare the performance of the two spectrum allocation schemes under different traffic patterns.