Numerous efforts are underway to develop testing and experimentation tools to evaluate the performance of networked control systems (NCS) and supervisory control and data acquisition (SCADA) systems. These tools offer varying levels of fidelity and scale. Yet, researchers lack an experimentation framework for systematic testing and evaluation of NCS reliability and security under a wide range of failure scenarios. In this paper, we propose a modular experimentation framework that integrates the NCS semantics with the DETERLab cyber security experimentation facilities. We develop several attack scenarios with realistic network topology and network traffic configurations to evaluate the impact of denial of service (DoS) attacks on scalar linear systems. We characterize the impact of the attack dynamics on six plants located at various levels in a hierarchical topology. Our results suggest that emulation-based evaluations can provide novel insights about the network-induced security and reliability failures in large scale NCS.