  Understanding queuing dynamics of TCP is important for correct router buffer
sizing as well as for optimizing the performance of the TCP protocol itself.
However, modeling of buffer content dynamics under TCP has received relatively
little attention given its importance. Commonly used queuing models are based
on overly simplistic assumptions about the packet arrival process. As a
consequence, there are no quantitatively accurate closed loop TCP models
capable of predicting performance even for a single link shared by multiple
flows. Our present paper aims to close this gap by proposing a simple TCP
queuing model, which is based on experimental observations and validated by
extensive packet level simulations.
