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Abstract. This paper defines a new restoration strategy for provisioning bandwidth guaranteed recovery for multicast connections in presence of link failures. The new restoration strategy is formulated into a new Integer Linear Programming (ILP) algorithm and is compared with other existing restoration strategies. We also present a new heuristic algorithm based on this new restoration strategy. Results show that our heuristic algorithm performs competitively close to the ILP-based algorithm, and is more bandwidth efficient than other existing heuristic algorithms that are based on different restoration strategies. 1

Abstract—Optical network survivability becomes indispensable with the emerging wavelength-division multiplexing (WDM) technologies such as the DWDM technology. Particularly, for optical multicast sessions, a link-or-node failure has a severe impact as it can prune several communications simultaneously. The p-cycle approach ensures node-and-link failure recovery while maintaining a fast restoration time and an efficient use of the network capacity compared to the other protection approaches. Up to now, most researches on link-and-node failure recovery in optical light trees have deployed limited approaches for node protection. These approaches do not use efficiently the protection capacity provided by a p-cycle when protecting nodes. In this paper, we extend the node protection concept of the p-cycle approach for an efficient resource utilization in a dynamic multicast traffic. Then, we propose two novel algorithms that integrate our concept for the node protection, named NPC and NPCC. These algorithms enable node-and-link failure recovery. We compare our algorithms with the ESHN algorithm, which is reported to be the most efficient heuristic algorithm for protecting dynamic multicast sessions in WDM networks. Extensive simulations show that the NPC algorithm achieves the best resource utilization, while the NPCC algorithm outperforms the ESHN algorithm in terms of blocking probability and computational time. I.

Abstract—Maintaining survivability of DWDM networks is crucial to multicast traffic. A link-or-node failure has a severe impact on optical multicast sessions as it can prune several communications simultaneously. In this paper, we present a novel candidate-cycle-based heuristic algorithm for node-andlink protection (CCHN) in dynamic multicast traffic. CCHN is based on p-cycle protection concept. The p-cycle concept ensures a fast restoration time and an efficient use of network capacity. Extensive simulations show that the blocking probability of our algorithm is lowest. Furthermore, the computational time of our algorithm is very low compared with the existing approaches, especially when traffic load is high. I.

Abstract—In this paper, we study the node and link protection using p-cycles for dynamic multicast sessions in alloptical DWDM networks. First, we propose a new concept for protecting nodes of light-trees under the sparse light-splitting and wavelength continuity constraints. Then, we integrate our concept in a novel algorithm, named node and link protecting candidate p-cycles based algorithm with sparse light-splitting constraints (NPCC-SSC). Our algorithm enables both node and link failure recovery in dynamic multicast traffic. Extensive simulations show that the NPCC-SSC algorithm achieves the best resource utilization, and outperforms the existing approaches in terms of blocking probability and computational time. I.