All-optical Interconnect Supporting Transparent Multi-hop Connection And The Routing And Spectrum Assignment In Data Centers

With a rapid growth of bandwidth-hungry applications,the capacity demand for data center networks has been increasing sharply.In addition to high capacity,low energy consumption is another indispensable requirement of data centers for sustainable development.In this regard,the all-optical interconnection is proposed as the approach for realizing the greener data center with larger capacity.A novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed.An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches(WSSs)in an intermediate rack rather than by relaying through optical-electric-optical(O-E-O)conversions.Compared with the conventional O-E-O based approach,the proposed all-optical scheme is able to off-load the traffic at intermediate racks,leading to a reduction of the power consumption and cost.The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats,baud rates and numbers of hops during the all-optical path are investigated by Monte-Carlo simulations.The error rate at receiver with varying received optical power(ROP)is assessed.We further investigate the proposed all-optical interconnection scheme by applying the number-of-hop adaptive bandwidth allocation approach to improve the spectrum efficiency(SE).The SE performance is evaluated with the different modulation formats and the numbers of hops in the path.The impact of parameters,such as the targeted error rate level and insertion loss of components,on the transmission performance of the proposed adaptive approach are also explored.The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.To take full advantage of the proposed all-optical multi-hop interconnect scheme,we proposed a hybrid routing scheme with an adaptive spectrum assignment(i.e.,Pathpro RSA).Compared with conventional spectrum assignment algorithms(RSA)developed for a multihop network with optical-electric-optical(OEO)conversion in every hop(i.e.,"EO"RSA),the proposed RSA achieves better utilization of bandwidth variable transceiver(BVT).While the proposed RSA also realizes the higher utilization of spectrum resource and enhances connectivity by eliminating the number-of-hops limitation when compared to the algorithm devised for an all-optical multihop network(i.e.,"AO" RSA).Simulations for the system are carried out to investigate the performance of the proposed algorithm.The impacts of various parameters,such as traffic load,ratio of connection requests with different data rates,resource configuration,the connection degrees(i.e.,the maximum number of ports that one rack has in order to connect to the core switch)and the number of racks on the optimal link cost and blocking probability(BP)performance is evaluated.The results show that the proposed RSA with appropriate cost functions outperforms the "EO" and "AO" RSA.The proposed RSA provides the best utilization of network resources and highest scalability for the flex-grid all-optical interconnection scheme in the core switch of data center.