This project aims at the design, analysis, and experimental evaluation of QoS-aware intra- and inter-domain routing solutions, with particular focus on performance and scalability. The goal of QoS routing is to identify a path through a network or series of networks that has sufficient resources to satisfy a set of constraints and, when possible, to optimize the selection of such a path. Typical constraints include bandwidth, maximum delay, reliability, administrative weight, etc. Requesters of constraint-based paths can be end-systems conveying their requirements through protocols such as RSVP, or network administrators attempting to provision paths for traffic engineering purposes. QoS routing represents a radical shift from the traditional connectivity-based routing approach. It brings with it a host of challenges that are being addressed in this project. These include computational issues related to finding feasible routes, path discovery under partial knowledge of the network state, state aggregation, and scalability considerations (e.g., amount of information that needs to be maintained at participating routers).