HighFidelity Router Emulation Technologies Based on MultiScale Virtualization Virtualization has the advantages of strong scalability and high fidelity in host node emulation. It can effectively meet the requirements of network emulation, including large scale, high fidelity, and flexible construction. However, for router emulation, virtual routers built with virtualization and routing software use Linux Traffic Control to emulate bandwidth, delay, and packet loss rates, which results in serious distortions in congestion scenarios. Motivated by this deficiency, we propose a novel router emulation method that consists of virtualization plane, routing plane, and a traffic control method. We designed and implemented our traffic control module in multiscale virtualization, including the kernel space of a KVMbased virtual router and the user space of a Dockerbased virtual router. Experiments show not only that the proposed method achieves highfidelity router emulation, but also that its performance is consistent with that of a physical router in congestion scenarios. These findings provide good support for network research into congestion scenarios on virtualizationbased emulation platforms.

Toward Comprehensive Network Verification: Practices, Challenges and Beyond Guaranteeing that large scale networks are always operated as policy goals dictate is critical for network availability, security, and performance. The problem is challenging, as it should not only assure the correctness of policy configurations across various network devices, but also guarantee the faithfulness of policy enforcement on actual packet forwarding behaviors. In this article, we provide a systematic overview of the direction of network verification, which covers both verification of network configurations and assurance of device actual behaviors. In particular, we summarize stateoftheart designs with focuses from early stateless data planes with switchesrouters to more recent stateful ones containing middleboxes. After analyzing and comparing these works, we also specify future directions in the verification of stateful networks.