Optimal mapping of virtual networks considering reactive reconfiguration

Network Virtualization (NV) has recently been considered as a key feature of the Future Internet because it allows easy transition from existing IPv4 based Internet to new mechanisms and protocols, and a more efficient usage of infrastructure by sharing it with different virtual network operators while deploying new services. However, Network Virtualization also raises new challenges for network operators [1]. One of the main challenges is the efficient resource allocation, known as virtual network mapping problem, in which virtual nodes and links are embedded to specific substrate nodes and paths. In this paper, we study this problem for the online scenario, where virtual network requests come and leave dynamically while considering the ability to reconfigure (re-arrange) the currently mapped virtual networks. All the recent research on this topic just focuses on the acceptance ratio of the virtual networks but do not address the possible service disruption during the reconfiguration. This paper proposes a so-called reactive reconfiguration mechanism, which reacts to any rejection of new coming virtual network requests. If a virtual network is rejected due to the lack of physical resources, the mechanism is triggered to reconfigure the currently-mapped networks so that the new request can be embedded. At the same time, it minimizes the number of necessary changes to reduce the service disruption. The mechanism is mathematically formulated as Integer Linear Programming (ILP) problem and solved by CPLEX [2]. Its performance is then evaluated through extensive simulations and compared with the case of no reconfiguration. A heuristic is then proposed to speed up the solving time of the ILP problem while maintaining its performance.