Research Of Optical Interconnect And Control Scheme In Intra-data Center Network

Over the last few years, the exponential increase of the Internet traffic, mainly driven from emerging applications like streaming video,social networking and cloud computing has created the need for more powerful warehouse data centers. These data centers are based on thousands of high performance servers interconnected with high performance switches. The applications that are hosted in the data center servers (e.g., cloud computing applications, search engines, etc.) are extremely data intensive and require high interaction between the servers in the data center. This interaction creates the need for high bandwidth and low latency communication networks between the servers in the data centers. Furthermore, these data centers must comply with low power consumption requirements in order to reduce the total operating cost.Our work is based on the demand of intra data center network for higher bandwidth and lower energy consumption, optical interconnect is employed to address these issues from following aspects: the scalability of the system, the flexibility of switching, and the variety of traffic granularity. The main innovative research achievements are listed as follows.Firstly, to address the issue of scalability, we propose a novel DCN architecture based on cascaded Micro-Electro-Mechanical Systems Switches (MEMS-switches) for dynamic DCN connectivity provisioning.This architecture provides high port count which attributes to the demands of the intra-data center traffic. The whole network is based on the centralized control.Secondly, to address the issue of flexibility, MUX/DEMUX& WSS module is proposed, which enables traffic defragmentation and traffic grooming functionality. MUX/DEMUX&WSS module allows more routing choices especially for the traffic with the same destination. We can implement the routing through merging the traffic with different wavelengths to the same destination together in the optical domain, thus there is less contention in the routing process, at the same time, enhancing the utilization of the input/output ports. In this case, the blocking probability and latency of the whole networks decrease.Thirdly, to address the issue of multiple granularity switching,MUX/DEMUX&SSS module is proposed at the background of utilizing bandwidth-variable transceiver. The spectrum allocation is done for each optical connection with the required number of subcarriers, thus, multiple requests can be modulated to the same superchannel and partitioned to single client request to different destination by using MUX/DEMUX&SSS module.Fourthly, to address the issue of finer granularity switching,mixed-fixed/flex grid transceivers is proposed for intra data center network. Flex-grid transceivers provide more spectrum efficiency than the fixed-grid transceivers. Thus, super server and one to multiple nodes communication can be served more efficiently. Numerical results shows that mixed flex-grid transceivers have a better performance than the fixed-grid ones in terms of service latency and blocking probability. A traffic monitor algorithm is proposed under the centralized control scheme. Finer granularity routing can be achieved through this algorithm,which further improves the spectrum utilization.Fifthly, to realize the all-optical data center interconnect, a hybrid of optical circuit switching and optical burst switching interconnect is proposed, by using the switch and interface card(SIC), servers can be connected directly to the hybrid OCS and OBS optical switches. The SIC can realize the functionality of aggregation of various traffic for different latency requirements.Traffic can be separated according to the requirement of service latency and transmitted to the OCS or OBS switching module.In terms of control scheme, a hybrid of OCS-based centralized control and OBS-based distributed control is employed.