Nested Virtualization Without the Nest

With the increasing popularity of containers, managing them on top of virtual machines becomes a common practice, called nested virtualization. This paper presents BrFusion and Hostlo, two solutions that address each of two networking issues of nested virtualization: network virtualization duplication and virtual machine-bounded pod deployments. The first issue lengthens network packet paths while the second issue leads to resource fragmentation. For instance, in respect with the first issue, we measured a throughput degradation of about 68% and a latency increase of about 31% in comparison with a single networking layer. We prototype BrFusion and Hostlo in Linux KVM/QEMU, Docker and Kubernetes systems. The evaluation results show that BrFusion leads to the same performance as a single-layer virtualization deployment. Concerning Hostlo, the results show that more than 11% of cloud clients see their cloud utilization cost reduced by down to 40%.