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Nowadays, with the increasing complexity of network structure and the application of diverse kinds of services, some problems, such as multicast-enabled routing, spectrum allocation and traffic protection, have become complicated in elastic optical networks (EONs). Since the transmission failure in EONs may lead to traffic interruption and thus causes serious economic loss, their ability to provide different modes of transmission, including unicast and multicast transmissions, with survivability is highly desirable. In this paper, aiming at improving the service blocking performance in realizing efficient protection for multicast services in EONs, we propose a leaf-looping based multicast protection algorithm, namely Multicast Protection with Leaf Loops (MPLL), which divides the destination nodes of multicast services into several groups according to their distance and constructs one loop for each group to provide protection for each destination node in the group. In constructing each destination loop, the shortest path algorithm is employed to minimize the cost of each generated loop. Besides, distance-adaptive spectrum allocation strategy is adopted for resource assignment to reduce the spectrum consumption in the proposed algorithm. In the research of protection technology, traditional P-cycle technology is an efficient optical network protection strategy, which has the characteristics of fast loop recovery speed and effective network recovery capacity. However, the P-cycle protection technology is pre-computed, which cannot meet the requirements of dynamic recovery. The leaf loops proposed in this paper are generated dynamically according to the destination nodes generated by each service, and can meet the dynamic business requirements. In addition, under the same blocking conditions, MPLL saves more path resources than P-cycle based algorithms in the protection path. Simulation results show that the proposed MPLL algorithm can realize multicast protection for EONs with low service blocking probability and high flexibility.
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