A novel highly-scalable matching policy for input-queued switches with multiclass traffic

We present the Distributed Frame-Definition Algorithm (DFDA), a novel scheduling policy for input-queued switches with virtual output queueing at the input line cards. The DFDA effectively supports the integration of traffic classes with diverse Quality-of-Service (QoS) requirements (as compelled by emerging QoS frameworks such as Differentiated Services), and scales well with the aggregate capacity of the switch because of the limited complexity of its distributed implementation. The input and output tine cards exchange a minimal amount of control information to define the periodic service schedule that regulates transit through the switch fabric. The composition of the service schedule dynamically adapts to the tight bandwidth requirements of real-time traffic and to the load fluctuations of best-effort traffic. We assess the performance of the DFDA through simulation, and compare it with the most popular scheduling algorithms for input-queued switches. Our experiments show that the DFDA generally sustains higher throughput than the schemes of the prior art.