XT-considered multiple backup paths and resources shared protection scheme based on ring covers.

With the rapid development of space division multiplexing (SDM) and flexible grid technology, the problem of resource allocation in optical network becomes much more complicated. Although there emerge a substantial number of works about link protection or restoration in SDM-EONs mesh networks, the topic of survivability is dug deeper in this work. It is acknowledged that protection schemes based on ring covers bring the advantages of shorter restoration time and lower costs. However, the RSCA problem in SDM-EON for link protection based on ring covers has rarely been investigated. To enhance the survivability of SDM-EON and make the best use of ring covers, we initially select a set of rings for the protection of all the links in a network topology according to constrains, aiming at taking full advantages of network resources. After that, we propose an algorithm to recover the traffic which will break off under link failures, basing on the set of rings. At the end of this protection scheme, we arrange the resources fulfilling the constrains of spectrum contiguity and core continuity constrains by using several different algorithms considering physical impairment. Based on the allocation in both spacial and spectral dimensions, our algorithms achieve better results of survivability. According to the simulations conducted for the evaluation of the proposed algorithms, our algorithms manage to recover at least 72.8% of traffic when the traffic request number is set to be 1000.