In the uncoordinated manner
In the uncoordinated manner?, ?Yuy and et al?. ?\cite{Ref001} propose a heuristic optimization algorithm for VNE?. ?The main goal in their approach ?was? maximizing the long-term average revenue and they had two independent phases?: ?virtual node mapping follows a greedy algorithm?, ?that selects a set of eligible substrate nodes for each virtual node and assigns one of them based on its amount of available resources?. ?Virtual link mapping follows the k-shortest path algorithm?, ?that selects a set of eligible substrate links for increasing k and then assigns one of them based on its amount of available bandwidth?. ?Houidi et al?. ?\cite{Ref002} in 2008 had designed a distributed VNE algorithm responsible for load balancing with a heuristic algorithm?. ?Their algorithm has completed in two stage?. ?The first stage is called the selection of hub-and-spoke?, ?that finds the virtual node with the highest capacity as the hub of the cluster and determines the ?neighboring? virtual nodes directly connected to the hub node to reperents the spoke nodes?. ?Then removes all hub and spoke nodes and repeats the process to find all hub-and-spokes?. ?The second stage is called mapping of hub-and-spokes?, ?that selects a substrate node with high remained capacity and embeds the first hub on it and the selected node should be mapped all itself spokes on the substrate network and repeats this process for all available hubs?. ?Sometimes providing the backup resources can increase the availability ?and? accessibility of virtual networks and decrease the failure ratio in embedding?. ?Ref \cite{Ref003} uses this concept and provides shared backup resources for each virtual network?. ?shared backup reserves resources as the backup for some virtual networks and they will be replaced by the destruction of any virtual network?.
