A scalable family of high-speed switch architectures

In this paper we present a scalable and recursive class of banyan switching architectures called the shared-tree banyan networks (STBN). For ATM networks, STBN can be engineered between two extremes: (1) a low-cost banyan with internal and external conflicts, or (2) a high-cost conflict-free fully-connected network with multiple outlets. STBN scalability is based on: (1) scalable concentrator bandwidth, and (2) controllable internal conflicts using path dilation. Scaling up the concentrator bandwidth leads to better utilization of the internal resources in blocking structures. Increasing path dilation increases service rate and cost. Evaluation shows that a small concentrator bandwidth combined with a moderate dilation degree produces a significant decrease in CLP by up to 10^-3 fold compared to the standard banyan. The STBN provides an effective tool for the scalability of banyan networks. It is very selective in bandwidth allocation by favoring higher-priority traffic which provides QoS guarantees for selectively switching real-time traffic. To gain scalability, high-speed switching architectures can use the STBN as a basic banyan.