Distributed and Efficient Network Hypervisor for SDN Virtualization

This article proposes a novel Distributed and Efficient Network Hypervisor (DeNH) to virtualize Software Defined Networking systems. DeNH adopts container- based architecture to reduce the extra delay imposed by the hypervisor, and provides efficient inter-hypervisor coordination to support global network embedding and global network addressing and control logic mapping table, leading to larger network scalability and higher network performance. A lightweight caching system with a record pre-fetching mechanism is proposed to significantly increase the cache hit rate for a further delay reduction in setting up flow entries. DeNH proposes to use the packets forwarded to the hypervisors in the control plane for flow setup to generate global network statistics. Such strategy significantly reduces the overhead imposed by shipping statistics from data to control planes. Evaluations over emulated SDN systems demonstrate the extra flow setup delay added by DeNH is very short. While the cache hit rate of DeNH is estimated to 100% using the traces of real data centres, the statistics maintained by DeNH can give an accurate detection of elephant flows in networks.