Substrate network house cleaning via live virtual network migration

Network virtualization techniques aim at efficiently allocating the underlying substrate network (SN) resources to the hosted virtual networks (VNs). Unfortunately, over time, and due to the frequent initiation and termination of VNs, the available and utilized SN resources become fragmented. This in turn, gradually degrades the performance of these techniques. In this paper, we propose a novel proactive SN resource re-optimization technique that efficiently overcomes the fragmentation problem by performing appropriate re-arrangement, or house cleaning, for the available and utilized SN resources. To minimize the incurred computational overhead, the invocation of this technique is only triggered by certain events such as the departure of an expired VN. The contributions of the proposed work are two fold; first, we develop an efficient technique for the selection and re-allocation of VN portions that are contributing to the fragmentation problem. The technique takes into consideration the trade-off between the benefit from increasing the SN utilization and the cost incurred by the VN migration. The second contribution is novel VN live migration techniques that significantly reduce the service interruption time during migration. Simulation experiments demonstrate the achieved gain in the SN resource utilization as well as in the VN acceptance ratio and the net revenue.