A Virtual Network Embedding Algorithm for Providing Stronger Connectivity in the Residual Networks

Abstract

How to efficiently map the nodes and links in a given virtual network (VN) to those in the substrate network (SN) so that the residual substrate network (RSN) can host as many VN requests as possible is a major challenge in virtual network embedding. Most research has developed heuristic algorithms with interactive or two-stage methods. These methods, however, could cause the RSN fragmented into several disconnected components that are insufficient to host a large number of given VN requests.<br />Without loss of generality, we assume that SNs, as the Internet, are small world and scale free, meaning that the average number of hops between any two nodes is a small constant and that most nodes have small degrees while only a small number of nodes have large degrees. Taking advantage of these two properties, we devise in this paper a new twostage VN embedding approach to improve the connectivity of the residual substrate network so that it has the capacity to host more VN requests. Our algorithm uses a greedy strategy that maps neighboring VN nodes to substrate nodes whose distances are bounded by a small constant. We also map the edge nodes of given VN, i.e., nodes with small degrees, to nodes with large degrees in the SN. We then map the links by solving shortest path problems. Our experimental evaluations show that our algorithms offer better mappings and results in significantly fewer rejections for VN requests

Service disruption index (SDI): A novel user perspective reliability indicator for modern virtual service networks

“…User‐perspective reliability means that even in the presence of failure, the system is said to be highly reliable if the requested demand can reach the destination within the time duration . Unfortunately, existing reliability analyses for the telecommunication networks focus on system‐level reliability by using probability‐connectivity and probability‐capacity models, which ignore the actual demand traffic inside the network. In addition, VoIP and the proposed SDI can be used to quantify the degree of actual user‐perceived reliability level.…”

“…Service dependency : One of the necessary characteristics in VSN reliability metric is that it is applicable with any type of service network. Among compared metrics, topology‐related and capacity‐related metrics are independent to the type of service. Likewise, our SDI has minimum degree of service dependency since the basic units used in our proposed VSN models are SLA‐independent.…”

“…However, most studies investigate the failures that occurred from the particular sources. For instance, the works of Luo et al and Gomes et al address the failures from the physical sources.…”

“…The initial studies on network reliability analysis focused on network connectivity, ie, the probability that there is a path of operational elements from a specific node to another node in the network. With the assumptions that the nodes fail independently to each other and links are completely reliable, it considers the network is reliable if the surviving nodes induce the connected subgraph …”

“…With the assumptions that the nodes fail independently to each other and links are completely reliable, it considers the network is reliable if the surviving nodes induce the connected subgraph. 22 Another measure is k-terminal reliability, 23 which is the probability that the set of k-specified nodes in the network are connected. A special case of k-connectivity metric is multipath connectivity, 24 which considers the alternative paths between each source and destination pair inside a network.…”