现有存储转发(SnF)调度方法的计算复杂度高、状态维护难度大, 严重制约了其在大数据传输领域的应用, 且传统全局建模导致调度问题中出现大量冗余状态。针对此问题, 提出了一种基于时移多层图(TS-MLG)的网络状态融合调度方法。该方法通过对预选路径的状态融合, 减少了冗余状态, 提高了算法的调度效率。仿真结果表明: 相比传统调度方法, 该方法的计算时间短、调度性能好, 且状态维护数量少, 能够为大规模网络提供实时、高效的调度服务。

Efforts in realizing all-optical packet switching are overwhelming in the past decade. While optical packet switching remains an attractive switching paradigm in the long run, technical challenges prohibit it from becoming a practical solution for the ever-growing bandwidth hunger during the next few years. Finding a technically viable way to meet the increasing capacity requirement with good scalability and flexibility becomes a clear pursue for the community. Hybrid packet and circuit switching is considered to be one promising technique in realizing high performance switching at low cost and less energy consumption, by taking the advantage of both packet switching and circuit switching. In this paper, we review existing work in hybrid optical packet and circuit switching. We discuss the key technical challenges in realizing hybrid optical packet and circuit switching. We further introduce our ongoing efforts in building a seamlessly transformable packet/circuit-switching node with hybrid optical and electronic components. We show that in a hybrid node, the scheduling complexity with typical scheduling algorithms may be reduced to half of a node running in full packet switching mode.

拓扑学上的光网络由边（光传输）和节点（光交换）组成。从业务属性出发，基于连接和无连接方式，分析了光交换的时间结构，包括光分组和光突发的时间结构，以及不同动态性的光电路交换的时长及其度量标准，结合实验结果分析了最短光电路交换的时长极限。从多端口和大容量的要求出发，重点讨论了基于微电子机械系统(MEMS)开关、波长选择开关(WSS)和阵列波导光栅(AWG)的三种光交换结构。分析了光交换结构的扩展方法，并讨论了光交换的几个具有挑战性的问题，包括缓存和能耗问题。通过分析，希望从时间和空间两个维度更清晰地认识光交换的本质及其与电交换的异同。

We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a single semiconductor optical amplifier (SOA). Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability. The operation principle is explained in detail. By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.

The stable multicast flow aggregation (MFA) problem in internet protocol (IP) over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access routers attached to the optical network, in which each head end can provide a set of programs (IP multicasting flows) and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of access routers changed dynamically. We introduce a program correlation matrix to describe the preference of end users’ requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first (MCPF), is presented and compared with the extended least tree first (ELTF) algorithm which is topology-aware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage.