The InfiniBand Architecture (IBA) is envisioned to be the default communication infrastructure for future System Area Networks (SANs) or clusters. The first release of the IBA specification outlines the importance of QoS provisioning in IBA to support real-time applications. The proposed research addresses five intertwined issues for designing QoS-capable IBA fabrics. First, we will perform design and analysis of switches/routers, network interface cards, and various network topologies to provide high and predictable performance in SANs. Second, we will propose efficient congestion avoidance techniques to handle network saturation. Next, efficient multicasting mechanisms for IBA switches will be investigated. Fourth, we will implement fault-tolerant techniques to make the QoS support robust to link and switch failures. Finally, a comprehensive simulation testbed for IBA SANs will be developed integrating these designs. The research, planned to be conducted in collaboration with Intel, will have the following contributions: (i) Efficient switched network architectures and NIC designs will be proposed to implement QoS-capable IBA fabrics; (ii) Research in the above five areas will provide novel solutions to satisfy end-to-end QoS requirements and will foster new ideas; and (iii) The simulation platform can be used as an effective tool for conducting future research on IBA.