Multiple leaf-ringing based protection algorithm with spectrum defragmentation for multicast traffic in elastic optical network

•We propose a multiple leaf-ringing based protection algorithm with spectrum defragmentation.•The proposed algorithm sorts the destination nodes of a multicast service into groups.•The proposed algorithm constructs one leaf ring for all the destination nodes in one group.•The proposed algorithm constructs two dedicated trunk paths from the source to each constructed ring.•The proposed algorithm triggers spectrum defragmentation to re-optimize resource utilization. Elastic optical networks (EONs) have realized high-speed data transmission with attractively efficiency and flexibility in resource utilization. In order to guarantee the reliability and increase the efficiency of the multicast transmission in EONs, we propose a multiple leaf-ringing based protection algorithm with spectrum defragmentation (MLRP-SD) in this article. The proposed algorithm firstly sorts the destination nodes of a multicast service into multiple groups. Then, it constructs one leaf ring for all the destination nodes in one group and two dedicated trunk paths (including one protection trunk path) from the source to each constructed ring. Since a leaf ring can provide protection for the destination nodes in its corresponding group, the reliability of multicast traffic can be improved. And the use of leaf rings can reduce the spectrum consumed in service protection compared to the traditional dedicated path protection (DPP) algorithms. In order to further improve the efficiency, the proposed MLRP-SD algorithm triggers spectrum defragmentation to re-optimize resource utilization in the network when sufficient available spectrum resources cannot be found along the sought protection trunk paths. The simulation results show that the proposed MLRP-SD algorithm can guarantee the reliability of multicast traffic with low service blocking probability.