Virtual network embedding based on real-time topological attributes

As a great challenge of network virtualization, virtual network embedding/mapping is increasingly important. It aims to successfully and efficiently assign the nodes and links of a virtual network （VN） onto a shared substrate network. The problem has been proved to be NP-hard and some heuristic algorithms have been proposed. However, most of the algorithms use only the local information of a node, such as CPU capacity and bandwidth, to determine how to map a VN, without considering the top- ological attributes which may pose significant impact on the performance of the embedding. In this paper, a new embedding algorithm is proposed based on real-time topological attributes. The concept ofbetweenness centrality in graph theory is borrowed to sort the nodes of VNs, and the nodes of the substrate network are sorted according to the correlation properties between the former selected and unselected nodes. In this way, node mapping and link mapping can be well coupled. A simulator is built to evaluate the performance of the proposed virtual network embedding （VNE） algorithm. The results show that the new algorithm significantly increases the revenue/cost （R/C） ratio and acceptance ratio as well as reduces the runtime.

研究目的:基于虚拟网络请求和底层物理网络实时拓扑属性,提出一种高效的两步式虚拟网络映射算法。创新要点:分别利用中介中心性和物理节点相关性对虚拟网络请求和底层物理网络中节点进行重要性评估,在此基础上给出一种两步式映射算法(算法1,2)。研究方法:首先给出中间中心性、接近中心性以及节点相关性计算模型,结合节点本地资源分别提出虚拟网络请求和物理网络中节点排名计算方式。当虚拟网络请求到达后,根据虚拟节点排名,将其映射到拥有足够资源的物理节点中排名最靠前的节点。节点映射完成后,使用K-th最短路径算法进行链路映射。映射过程中采用文献(Yu et al.,2008)中所使用的时间窗口模式进行接入控制。重要结论:利用节点本地资源,针对性分析虚拟网络请求和物理网络实时拓扑属性,提出两步式映射算法。该算法提高请求接受率、开销收益比的同时减少算法映射时间,取得更好的映射效果(图3-10)。