Applying Bidirectional Crossbar Switches with Extra Sets of Inlets and Outlets to Three-Stage Clos Networks
AUTHORS
Labson Koloko,Graduate School of Engineering Science, Akita University, Japan
Hitoshi Obara*,Graduate School of Engineering Science, Akita University, Japan
ABSTRACT
In scaling up optical network capacity in space-division multiplexing, the three stage Clos network has been used for building high port count switches with reduced Crosspoint. This paper presents a new three stage Clos architecture with extra internal routes yielding a smaller number of crossbar switches. The three-stage Clos network, denoted by C(n, m, r), where n, m, and r represent the number of input (output) ports of the input (output) switches, the number of middle switches, and the number of input and output switches, respectively, is widely used. Here, we consider Clos networks that include conventional crossbar switch elements, which are composed of 22 basic cells often used in optical networks. First, we point out that the crossbar switches have a number of idle ports unused, and discuss how they can be employed to improve the network performance. We then introduce a new type of Clos network in which the middle stage is composed of bidirectional crossbar switches with extra sets of inlets and outlets. This is done by utilizing the idle ports on the crossbar switches. Second, we elaborate on the non-blocking performance of this network and show that the theoretical lower bound of m for rearrangeable non-blocking capability can be reduced by 25% of the original Clos network when idle ports are used. We also demonstrate that when m = n, the number of rearrangements is reduced to one at most, regardless of the values of n and r, while typical Clos networks require r 1 rearrangement in worst-case scenarios. Finally, we show that m in the wide-sense non-blocking bidirectional Clos network can be approximately 25% lower than in the conventional strictly non-blocking Clos network. With this result, the architecture can be applicable to three stage clos networks where the size of the middle switches is larger than that of inputs and outputs stages.
KEYWORDS
Switch network, Three-stage clos network, Non-blocking condition, Bidirectional switches, Rearrangeable non-blocking switch, Wide-sense non-blocking switch
REFERENCES
[1] W. Kabacinski, C. -T. Lea, and G. Xue, “Guest editorial - 50th anniversary of clos networks,” IEEE Communications Magazine, vol.41, no.10, pp.26-27, (2003), DOI:10.1109/MCOM.2003.1235590(CrossRef)(Google Scholar)
[2] Q. Cheng, M. Bahadori, Y. Hung, Y. Huang, N. Abrams, and K. Bergman, “Scalable microring-based silicon Clos switch fabric with switch-and-select stages,” IEEE Journal of Selected Topics in Quantum Electronics, vol.25, no.5, pp.1-11, (2019), Art no. 3600111, DOI:10.1109/JSTQE.2019.2911421(CrossRef)(Google Scholar)
[3] L. Wang, T. Ye, and T. T. Lee, “A parallel route assignment algorithm for fault-tolerant Clos networks in OTN switches,” IEEE Transactions on Parallel and Distributed Systems, vol.30, no.5, pp.977-989, (2019), DOI:10.1109/TPDS.2018.2880782(CrossRef)(Google Scholar)
[4] O. T. Sule and R. Rojas-Cessa, “TRIDENT: A load-balancing clos-network packet switch with queues between input and central stages and in-order forwarding,” IEEE Transactions on Communications, vol.67, no.10, pp.6885-6896, (2019), DOI:10.1109/TCOMM.2019.2926730(CrossRef)(Google Scholar)
[5] D. M. Marom et al, “Survey of photonic switching architectures and technologies in support of spatially and spectrally flexible optical networking,” IEEE/OSA Journal of Optical Communications and Networking, vol.9, no.1, pp.1-26, (2017), DOI: 10.1364/JOCN.9.000001(CrossRef)(Google Scholar)
[6] G. I. Papadimitriou, C. Papazoglou, and A. S. Pomportsis, “Optical switching: Switch fabrics, techniques, and architectures,” Journal of Lightwave Technology, vol.21, no.2, pp.384-405, (2003), DOI:10.1109/JLT.2003.808766(CrossRef)(Google Scholar)
[7] H. Obara, “Reduced crossbar switch with minimum number of switching cells,” Electronics Letters, vol.44, no.14, pp.888-889, (2008), DOI:10.1049/el:20083528(CrossRef)(Google Scholar)
[8] H. Obara, “Design of optical multi/demultiplexers composed of bidirectional 2×2 switch elements for reducing component count,” Electronics Letters, vol.51, no.15, pp.1182-1184, (2015), DOI:10.1049/el.2015.1526(CrossRef)(Google Scholar)
[9] C. -T. Lea, “Expanding the switching capabilities of optical cross connects,” IEEE Transactions on Communications, vol.53, no.11, pp.1940-1944, (2005), DOI:10.1109/TCOMM.2005.858662(CrossRef)(Google Scholar)
[10] H. Obara, “Cascaded versus parallel architectures of two-stage optical crossbar switches with an extra set of inputs and outputs,” IET Optoelectronics, vol.12, no.4, pp.196-201, (2018), DOI:10.1049/iet-opt.2017.0096(CrossRef)(Google Scholar)
[11] S. Ohta, “The number of rearrangements for Clos networks-new results,” Theoretical Computer Science, vol.814, pp.106-119, (2020), DOI:10.1016/j.tcs.2020.01.2018(CrossRef)(Google Scholar)
[12] C. Clos, “A study of nonblocking switching networks,” Bell Syst. Tech. J., vol.32, pp.406-424, (1953), DOI:10.1002/j.1538-7305.1953.tb01433.x(CrossRef)(Google Scholar)
[13] M. C. Paul, “Re switching of connection networks,” Bell Syst. Tech. J., vol.41, pp.833-855, (1962), DOI:10.1002/j.1538-7305.1962.tb00478.x(CrossRef)(Google Scholar)
[14] F. H. Chang, J. Y. Guo, F. K. Hwang, and C. K. Lin, “Wide-sense nonblocking for symmetric or asymmetric 3-stage clos networks under various routing strategies,” Theoretical. Computer Science, vol.314, no.3, pp.375-386, (2004), DOI:10.1016/j.tcs.2003.12.021(CrossRef)(Google Scholar)
[15] A. Jajszczyk and G. Jekel, “A new concept-repackable networks,” IEEE Transactions on Communications, vol.41, no.8, pp.1232-1237, Aug. (1993), DOI:10.1109/26.231967(CrossRef)(Google Scholar)
[16] H. Obara “Strictly non-blocking three-quarter crossbar switch with simple switch control,” IET Electronics Letters, vol.52, no.25, pp.2051-2053, (2016), DOI:10.1049/el.2016.3561(CrossRef)(Google Scholar)
[17] K. Goossens, L. Mhamdi, and I. V. Senin, “Internet-router buffered crossbars based on networks on chip,” 12th Euromicro Conference on Digital System Design, Architectures, Methods and Tools, Patras, Greece, pp.365-374, (2009), DOI:10.1109/DSD.2009.211(CrossRef)(Google Scholar)
[18] L. Mhamdi, K. Goossens, and I. V. Senin, “Buffered crossbar fabrics based on networks on chip,” 8th Annual Communication Networks and Services Research Conference, Montreal, QC, pp.74-79, (2010), DOI:10.1109/CNSR.2010.18(CrossRef)(Google Scholar)
[19] F. Hassen and L. Mhamdi, “Congestion-aware multistage packet-switch architecture for data center networks,” IEEE Global Communications Conference (GLOBECOM), Washington DC, pp.1-7, (2016) DOI:10.1109/GLOCOM.2016.7841681(CrossRef)(Google Scholar)
[20] F. Hassen and L. Mhamdi, “High-capacity clos-network switch for data center networks,” IEEE International Conference on Communications (ICC), Paris, pp.1-7, (2017), DOI:10.1109/ICC.2017.7997147(CrossRef)(Google Scholar)
[21] T. S. El-Bawab, “Optical switching,” 1st ed., Springer, Berlin, DE, (2010)
[22] K. Tanizawa, K. Suzuki, K. Ikeda, S. Namiki, and H. Kawashima, “Novel PILOSS port assignment for compact polarization-diversity Si-wire optical switch,” Optical Fiber Communications Conference and Exhibition (OFC), Anaheim, CA, paper number M31-6, (2016)
[23] F. K. Hwang, “The mathematical theory of nonblocking switching networks,” 2nd ed., World Scientific, London, UK, pp.59-67, (2004)
[24] S. Ohta, “A new result on rearrangeable 3-stage Clos networks,” 28th International Telecommunication Networks and Applications Conference (ITNAC), Sydney, NSW, pp.1-6, (2018), DOI:10.1109/ATNAC.2018.8615439(CrossRef)(Google Scholar)
[25] W. Kabacinski, “Nonblocking electronic and photonic switching fabrics,” 1st ed., Springer, Berlin, DE, pp.55-61, (2005)
[26] F. K. Hwang, W. Lin, and V. Lioubimov, “On non-interruptive rearrangeable networks,” IEEE/ACM Transactions on Networking, vol.14, no.5, pp.1141-1149, (2006), DOI: 10.1109/TNET.2006.882846(CrossRef)(Google Scholar)