Network virtualization stacks are the linchpins of public clouds. A key goal is to provide performance isolation so that workloads on one Virtual Machine (VM) do not adversely impact the network experience of another VM. Using data from a major public cloud provider, we systematically characterize how performance isolation can break in current virtualization stacks and find a fundamental tradeoff between isolation and resource multiplexing for efficiency. In order to provide predictable performance, we propose a new system called PicNIC that shares resources efficiently in the common case while rapidly reacting to ensure isolation. PicNIC builds on three constructs to quickly detect isolation breakdown and to enforce it when necessary: CPU-fair weighted fair queues at receivers, receiver-driven congestion control for backpressure, and sender-side admission control with shaping. Based on an extensive evaluation, we show that this combination ensures isolation for VMs at sub-millisecond timescales with negligible overhead.

This paper presents a new approach of dynamic symmetric key distribution for encrypting the communication between two nodes in a Wireless Sensor Network. The distribution of a shared key can be performed by any sensor node and does not always require that it is performed by the base station. Each node can be selected by one of its neighbor nodes in order to distribute a pair-wise key for a communication between two nodes. The selection is based on the local computation of a trust value granted by the requesting nodes. This paper also describes a dynamic trust-based route selection mechanism that each node performs to route data to any destination.

In previous works, we proposed a routing approach where nodes in a wireless sensor network (WSN) rely on trusted neighbors and neighborspsila reputation to dynamically select the best route to the destination. In this paper, we extend these previous works by adding mobile nodes to the WSN and investigating how the movements of nodes in a mobile WSN affect the success rate of routing data from a source to a destination. We also implement hostile nodes to test how our route selection and reputation mechanisms cope in their presence.