— In this paper we provide a survey of three classes of combinatorial optimization problems that arise in communication network analysis. These problems, referred to as QoS (Quality of Service) route selection problems, have assumed great importance in view of the stringent demands imposed on communication protocols to provide certain quality of service guarantees. We first give a broad overview of advances in these areas and then provide a discussion of algorithms that are of fundamental importance and significance to the networking community as well as operations research and computer science and engineering communities.