To cater to the demands of our rapidly growing Internet traffic, backbone networks need high-degree reconfigurable optical add/drop multiplexers (ROADMs) to simultaneously support multiple pairs of bi-directional fibers on each link. However, the traditional ROADM architecture based on the Spanke network is too complex to be directly scaled up to construct high-degree ROADMs. In addition, the widely deployed Spine-Leaf datacenter networks (DCNs) based on electrical switches consume too much power and exhibit high packet latency. Because of these issues, Clos networks are considered as promising alternatives for constructing large-scale ROADMs and all-optical DCNs. In this article, we look at a next-generation Clos-based ROADM architecture and show that it indeed provides better blocking performance with lower element and fiber complexities compared with a traditional Spanke-based ROADM architecture. We also discuss the application of a Clos network in all-optical DCNs to show that it can be used to effectively construct large-scale DCNs with significantly greater flexibility in supporting a variety of multicast services and in combining different network topologies.

翻译：为满足快速增长的互联网流量需求，骨干网络需要高端口数可重构光分插复用器（ROADM），以在每条链路上同时支持多对双向光纤。然而，基于Spanke网络的传统ROADM架构因过度复杂而难以直接扩展至高端口数ROADM的构建。此外，广泛部署的基于电交换机的Spine-Leaf数据中心网络（DCN）存在功耗过高及高分组延迟的问题。基于上述挑战，Clos网络被视为构建大规模ROADM及全光DCN的潜在替代方案。本文探讨了下一代基于Clos的ROADM架构，并证明相较于传统基于Spanke的ROADM架构，该方案确实能以更低的器件与光纤复杂度提供更优的阻塞性能。我们同时讨论了Clos网络在全光DCN中的应用，表明其能有效构建大规模DCN，并在支持多种多播服务及融合不同网络拓扑方面实现显著更高的灵活性。