Abstract: With the Internet evolved into a global commercial infrastructure, there has been a great demand for new applications of global reach, for which today�s Internet protocols cannot adequately support. The real-time applications, have stringent delay and delay jitter requirements, which cannot be adequately supported by today�s Internet protocols. As a result, in recent years, a large number of new Internet protocols were developed in an attempt to meet this demand. Multi-Protocol Label Switching (MPLS) has been envisioned as an ideal platform upon which guaranteed services could be developed. Service guarantee is achieved by setting up and managing a set of primary and backup Class-of-Service (CoS) aware label switched paths across an IP domain. In addition to MPLS, this approach requires a suite of protocols be implemented, e.g., DiffServ for Quality of Service (QoS), path protection/fast rerouting for link Failure Recovery (FR) and constraint-based routing for Traffic Engineering (TE). The proposed thesis develops a family of Distributed Traffic Control Laws (DCLs), which allows optimal, multiple CoSs, multipath based rate adaptation and load balancing. The DCLs drive the network to an operation point where a user defined global utility function is maximized. The proposed family of DCLs has, the capability to enable optimal, scalable QoS and Traffic Engineering, simultaneously.