ABSTRACT: Recent innovations in Network Virtualization and Elastic Optical Networks (EONs) enable flexible deployment of optical networks as a service. However, embed Virtual Optical Network (VON) requests onto the physical substrate network to maximize the sharing of physical resources, which is the so called Virtual Network Embedding (VNE) problem. EONs are prone to the fragmentation of spectral resources during the process of routing and spectrum allocation. The fragmentation of spectral resources in the substrate fiber links may lead to the blocking of incoming virtual network requests. This degrades the utilization of the physical resources of the Infrastructure Providers and also, decreases the revenue of the Service Providers. In this review, different model that takes into account the spectrum alignment and relative loss in spectrum consecutiveness when mapping virtual nodes/links onto the physical substrate nodes/links. It also observes a minmax reconfiguration scheme called Relative Consecutiveness Lossaware and Misalignment-aware Virtual Network Reconfiguration (RCLM-VNR) that minimizes relative consecutiveness loss and maximizes alignment with adjacent links when reconfiguring the virtual network. It also observes elasticity and traffic load.