In the last chapter, background information on dynamic systems and Lyapunov stability was introduced. In the remainder of the book, we will apply these concepts from control theory to the design and development of protocols for wired and wireless networks. It can be observed that by using the control theory concepts, one can demonstrate not only stability but also performance of these protocols, in terms of quality of service (QoS) metrics such as throughput, packet/cell losses, end-to-end delay, jitter, energy efficiency, etc. In particular, we will focus on the development of congestion and admission control, distributed power control and rate adaptation, distributed fair scheduling, and routing protocols for wired and wireless networks. First, we will apply the control system concepts to the design of congestion control protocol for wired networks.