Interconnection networks were traditionally confined to multiprocessors where low latency and high bandwidth were necessary for interprocessor communication. But in the last decade interconnection networks have become crucial in other application areas such as storage area networks and high performance computing clusters. This development has led to an increased interest in supporting quality of service in interconnection networks driven by the wish to converge cluster storage, cluster communication, and cluster management in one single network. In this thesis we propose and study a set of mechanisms to achieve this in existing interconnection technologies. We introduce two new topology agnostic routing algorithms, a service differentiation scheme for the InfiniBand Architecture, and several admission control schemes.