We study how to reduce the reconfiguration time in hybrid optical-electrical Datacenter Networks (DCNs). With a layer of Optical Circuit Switches (OCSes), hybrid optical-electrical DCNs can reconfigure its logical topologies to better match the on-going traffic patterns, but the reconfiguration time may directly affect the benefits of reconfigurability. The reconfiguration time consists of the topology solver running time and the network convergence time after triggering reconfiguration. However, existing topology solvers either incur high algorithmic complexity or fail to minimize the reconfiguration overhead. In this paper, we propose a novel algorithm that combines the ideas of bipartition and Minimum Cost Flow (MCF) to reduce the overall reconfiguration time. For the first time, we formulate the topology solving problem as a MCF problem with piecewise-linear cost, which strikes a better balance between solver complexity and solution optimality. Our evaluation shows that our algorithm can significantly reduce the network convergence time while consuming less topology solver running time, making its overall performance superior to existing algorithms. Our code and test cases are available at a public repository.

翻译：我们研究了如何减少混合光电数据中心网络（DCN）中的重配置时间。通过引入光电路交换机（OCS）层，混合光电DCN可重新配置其逻辑拓扑以更好地匹配当前流量模式，但重配置时间可能直接影响可重构性的收益。重配置时间由拓扑求解器运行时间与触发重配置后的网络收敛时间组成。然而，现有拓扑求解器要么算法复杂度较高，要么无法最小化重配置开销。本文提出了一种结合二分图划分与最小费用流（MCF）思想的新型算法，旨在降低整体重配置时间。我们首次将拓扑求解问题建模为具有分段线性成本的最小费用流问题，在求解器复杂度与解最优性之间实现了更好的平衡。评估表明，我们的算法在降低拓扑求解器运行时间的同时显著减少了网络收敛时间，其整体性能优于现有算法。我们的代码与测试用例已发布于公共代码仓库。