Virtual Network (VN) embedding is one of the key problems of network virtualiza-tion. It can be separated into two basic phases, the node mapping and the link mapping phases. Previous research mainly focused on the link mapping phase, while there are only few simple and crude solutions in node mapping phase. However, the result of node mapping has a significant impact on the performance of virtual network embedding. There are two major drawbacks of previous node mapping solutions. Firstly, nodes with sufficient bandwidth resources are first selected while finding the hosts, which is not good for resource utilization usually. Secondly, existing methods separate the two phases too clearly so that neighbor nodes in the virtual network may be mapped to faraway nodes in the substrate network, which causes virtual links to take more bandwidth resources. This paper proposes a new virtual network embedding algorithm with node distributed closely. We take all the substrate nodes that meet a virtual node' s requirement as its candidate hosts, so that there are more choices while selecting its host. It is conducive to rational allocation of resources. After that, we choose those closely distributed substrate nodes as the hosts of the virtual nodes, and those adjacent nodes in the virtual network request are mapped to substrate nodes in neighborhood. As a result, fewer resources are needed to finish link mapping. Simulation experiments show that the proposed algorithm improves resource utilization and increases the acceptance ratio significantly.%虚拟网络映射是网络虚拟化中最基本的问题之一.虚拟网络映射可分解成结点映射和链路映射两个阶段,之前的研究更加侧重于链路映射,对结点映射只采取简单的方式进行,不利于资源利用率的提高.之前的结点映射方法有两个主要问题:(1)优先占用带宽较大的结点,不利于资源的合理配置；(2)将结点映射与链路映射完全分隔处理,逻辑相邻的虚拟结点可能映射到分散的物理结点上,致使虚拟链路占用更多的网络资源.文中提出一种结点紧凑的虚拟网络映射方法,将所有符合条件的物理结点都作为虚拟结点的候选宿主,扩大了宿主的选择空间,有利于资源的合理配置；同时选择那些分布紧凑的结点作宿主,将相邻的虚拟结点映射到邻近的物理结点之上,减少虚拟链路对网络资源的占用.实验结果表明:文中方法可以提高资源的利用率,并显著地提高了虚拟网络请求的接受率.
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