The ever-expanding growth of internet traffic enforces deployment of massive Data Center Networks (DCNs) supporting high performance communications. Optical switching is being studied as a promising approach to fulfill the surging requirements of large scale data centers. The tree-based optical topology limits the scalability of the interconnected network due to the limitations in the port count of optical switches and the lack of optical buffers. Alternatively, buffer-less Fast Optical Switch (FOS) was proposed to realize the nanosecond switching of optical DCNs. Although FOSs provide nanosecond optical switching, they still suffer from port count limitations to scale the DCN. To address the issue of scaling DCNs to more than two million servers, we propose the hyper scale FOS-based L-level DCNs (HFOS\(_L\)) which is capable of building large networks with small radix switches. The numerical analysis shows L of 4 is the optimal level for HFOS\(_L\) to obtain the lowest cost and power consumption. Specifically, under a network size of 160,000 servers, HFOS\(_4\) saves 36.2% in cost compared with the 2-level FOS-based DCN, while achieves 60% improvement for cost and 26.7% improvement for power consumption compared with Fat tree. Moreover, a wide range of simulations and analyses demonstrate that HFOS\(_4\) outperforms state-of-art FOS-based DCNs by up to 40% end-to-end latency under DCN size of 81920 servers.

互联网流量的不断增长迫使部署支持高性能通信的大规模数据中心网络 (DCN)。光交换正在被研究作为一种有前途的方法来满足大规模数据中心的激增需求。基于树的光拓扑由于光交换机端口数的限制和光缓冲器的缺乏而限制了互连网络的可扩展性。或者，提出了无缓冲快速光开关 (FOS) 来实现光 DCN 的纳秒级切换。尽管 FOS 提供纳秒级光交换，但它们仍然受到端口数限制，无法扩展 DCN。为了解决将 DCN 扩展到超过 200 万台服务器的问题，我们提出了超大规模基于 FOS 的L级 DCN（HFOS\(_L\) )，它能够用小基数开关构建大型网络。数值分析表明， L为 4 是 HFOS \(_L\)获得最低成本和功耗的最佳水平。具体来说，在16万台服务器的网络规模下，HFOS \(_4\)与基于2级FOS的DCN相比，成本降低36.2%，与Fat tree相比成本降低60%，功耗降低26.7% . 此外，大量的模拟和分析表明，在 81920 个服务器的 DCN 规模下，HFOS \(_4\)的端到端延迟比基于 FOS 的最新 DCN 的延迟高出 40%。