p-Cycles offer ring-like switching speed and mesh-like spare capacity efficiency for protecting network against link failures. This makes them extremely efficient and effective protection technique. p-Cycles can also protect all the links in a network against simultaneous failures of multiple links. But it has been mostly studied for single link failure scenarios in the networks with the objective to minimize spare capacity under the condition of100% restorability. For large networks, use of p-cycles is difficult because their optimization requires an excessive amount of time as the number of variables in the corresponding Integer Linear Program (ILP) increase with the increase in the network size. In a real-time network situation,setting up a highly efficient protection in a short time is essential.Thus, we introduce a network sub-graphing approach, in which a network is segmented into smaller parts based on certain network attributes. Then, an optimal solution is found for each sub-graph. Finally, the solutions for all the sub-graphs is combined to get a sub-optimal solution for the whole network. We achieved better computational efficiency at the expense of marginal spare capacity increases with this approach.

中文翻译：

---

全光网络中跨度故障的子图p周期形成

p-Cycles具有环状交换速度和网格状备用容量效率，可保护网络免受链路故障的影响。这使其成为极为有效的保护技术。p-Cycles还可以保护网络中的所有链路，防止多个链路同时发生故障。但是，已经针对网络中的单链路故障场景进行了研究，目的是在可恢复性为100％的情况下最大程度地减少备用容量。对于大型网络，使用p周期是困难的，因为随着网络规模的增加，随着相应整数线性规划（ILP）中变量数量的增加，对p周期的优化需要花费大量的时间。在实时网络情况下，在短时间内建立高效的保护至关重要。因此，我们介绍了一种网络子绘图方法，其中，根据某些网络属性将网络细分为较小的部分。然后，为每个子图找到最佳解。最后，将所有子图的解决方案组合起来，以获得整个网络的次优解决方案。通过这种方法，我们以提高边际备用容量为代价，实现了更高的计算效率。