Publications

Admission and congestion control mechanisms are integral parts of any Quality of Service (QoS) design for networks that support integrated traffic. In this paper, we propose an admission control algorithm and a congestion control algorithm for clusters, which are increasingly being used in a diverse set of applications that require QoS guarantees. The uniqueness of our approach is that we develop these algorithms for wormhole-switched networks. We use QoS-capable wormhole routers and QoS-capable network interface cards (NICs), referred to as Host Channel Adapters (HCAs) in InfiniBandTM Architecture (IBA), to evaluate the effectiveness of these algorithms. The admission control is applied at the HCAs and the routers, while the congestion control is deployed only at the HCAs. Simulation results indicate that the admission and congestion control algorithms are quite effective in delivering the assured performance. The proposed credit-based congestion control algorithm is simple and practical in that it relies on hardware already available in the HCA to regulate traffic injection.

Design of high performance cluster networks (routers) with Quality-of-Service (QoS) guarantees is becoming increasingly important to support a variety of multimedia applications, many of which have real-time constraints. Most commercial routers, which are based on the wormholeswitching paradigm, can deliver high performance, but lack QoS provisioning. In this paper, we present a pipelined wormhole router architecture that can provide high and predictable performance for integrated traffic in clusters. We consider two different implementations—a non-preemptive model and a more aggressive preemptive model. We also present the design of a network interface card (NIC) based on the Virtual Interface Architecture (VIA) design paradigm to support QoS in the NIC. The QoS capable router and NIC designs are evaluated with a mixed workload consisting of best-effort traffic, multimedia streams, and control traffic. Simulation results of an 8-port router and a (2 2) mesh network indicate that the preemptive router can provide better performance than the non-preemptive router for dynamically changing workloads. Co-evaluation of the QoS-aware NIC with the proposed router models shows significant performance improvement compared to that with a traditional NIC without any QoS support