ملخص: The symbiosis of network virtualization and software-defined networking (SDN) enables an infrastructure provider (InP) to build various virtual software defined networks (vSDNs) over a shared substrate network (SNT). To handle a dynamic network environment, the InP may need to reconfigure the mapping schemes of vSDNs for a variety of reasons. Although previous studies have addressed how to calculate the new virtual network embedding (VNE) schemes for vSDN reconfiguration under different objectives, the transition to migrate vSDNs from their original VNE schemes to new ones is still under-explored. Hence, this paper studies how to realize parallel and hitless vSDN reconfiguration, by leveraging the "make-before-break" scenario. We come up with a generic solution to optimize the transition to remap vSDNs to new VNE schemes, such that the remappings can be done in the parallel, hitless and resource-efficient manner, as long as the new VNE schemes are feasible. More specifically, our proposal is the multi-stage parallel vSDN reconfiguration based on maximal connected reconfigurable sub-graph (MCRSG). To ensure the efficiency of our proposal, we formulate the optimization for selecting MCRSGs to reconfigure in each stage, and prove the N P-hardness of the problem. Then, we design an approximation algorithm based on Lagrangian relaxation to solve it time-efficiently. Extensive simulations verify that the proposed algorithm can obtain near-optimal solutions quickly. In addition to the algorithmic study, we also realize our multi-stage parallel vSDN reconfiguration in a practical NVH system, and demonstrate its performance in a real network testbed. Our experimental study identifies in what condition losing of packets during remapping would be inevitable, studies the tradeoff between reconfiguration latency and packet loss rate, and reveal an empirical method to adjust key parameters of our NVH system, for adapting to various network environments.

لغة: إنجليزية