Modeling TCP in Small-Buffer Networks

Today, the large packet buffers present in backbone routers significantly increase their power consumption and design time. Recent models of networks with large buffers have suggested that these large buffers could be replaced with much smaller ones. Unfortunately, it turns out that these models are not valid anymore in networks with small buffers, and therefore cannot predict how these small-buffer networks will behave. In this paper, we introduce a new model that provides a complete statistical description of small-buffer Internet networks. First, we present novel models of the distributions of several network components, such as the line occupancies of each flow, the instantaneous arrival rates to the bottleneck queues, and the bottleneck queue sizes. Then, we combine all these models in a single fixed-point algorithm that forms the key to the global statistical small-buffer network model. In particular, given some QoS requirements, this new model can be used to precisely size small buffers in backbone router designs.