Hybrid Testbeds for QoS Management in Opaque MANETS

The design of QoS mechanisms for wireless networks in general, and mobile ad hoc networks (MANETs) in particular, is a challenging task. The challenges are further compounded when the characteristics of the intermediate network segments are not observable from the originating segment, and as a consequence these segments have to be treated as opaque networks. End-to-end QoS assurance for such opaque networks, consisting of admission control and quality adjustment, can be based on techniques for dynamically measuring throughput representing the state of these networks. Testing these QoS mechanisms poses a special technical challenge due to the difficulty of conducting experiments in a MANET environment at a scale larger than a dozen nodes or so. In this paper, we describe a distributed and hybrid testbed that has been deployed for running large-scale experiments to demonstrate the efficacy of a measurement-based QoS solution. The infrastructure for the testbed provides an integrated platform consisting of real nodes running the actual software under test, augmented with a simulated network environment. We define a set of metrics and run experiments to evaluate the effectiveness of the QoS solution as well the performance of the deployed testbed. We propose an alternate architecture that employs a Xen-based virtualization of the real nodes from the deployed testbed. We compare the performances of the virtualized architecture with the non-virtualized one vis-à-vis latency and resource utilization. Our goal is to establish benchmarks for running large-scale experiments on performance and QoS measurements in virtualized environments.