We first provide an overview of the FAST TCP project at Caltech, the basic theory and some experimental results.  We will then focus on a new dynamic link model that generalizes existing models and agrees more closely with packet-level simulations.  We show that FAST TCP flows over a single link are always linearly stable regardless of delay distribution.  This result resolves the discrepancy between empirical observations and previous theoretical predictions.  The analysis highlights the critical role of self-clocking in TCP stability and the scalability of FAST TCP with respect to delay.