is further from equilibrium and smaller steps near equilibrium. This improves the speed of convergence and the stability. Strengths and weaknesses Delay-based algorithms can, in principle, maintain a constant window size, avoiding the oscillations inherent in loss-based algorithms. However, they also detect congestion earlier than loss-based algorithms, since delay corresponds to partially filled buffers, while loss results from totally filled buffers. This can be either a strength or a weakness. If the only protocol used in a network is delay-based, then the inefficiency of loss can be avoided; however, if loss-based and delay-based protocols share the network, then delay-based algorithms tend to be less aggressive. This can be overcome by suitable choice of parameters, leading to complex interactions studied by Tang et al. Delay measurements are also subject to jitter as a result of operating system scheduling, or bus contention. Whether the strengths or weaknesses prevail is not clear, and depends in large part on the particular scenario. Propagation delay is used in the FAST window control algorithm. In a clean network, the queueing delay maintained by existing FAST flows may be mistaken as part of the propagation delay by new flows that join later, as shown in ns-2 simulations in. The effect of this estimation error is equivalent to modifying the underlying utility functions to favor new flows over existing flows. Method to eliminate this error is suggested in. Generalized FAST TCP FAST TCP has been shown to be promising in terms of system stability, throughput and fairness. However, it requires buffering which increases linearly with the number of flows bottlenecked at a link. The paper proposes a new TCP algorithm that extends FAST TCP to achieve (α, n)-proportional fairness in steady state, yielding buffer requirements which grow only as the nth power of the number of flows. The authors call the new algorithm Generalized FAST TCP. They prove stability for the case of a single bottleneck link with homogeneous sources in the absence of feedback delay. Simulation results verify that the new scheme is stable in the presence of feedback delay, and that its buffering requirements can be made to scale significantly better than standard FAST TCP. Intellectual property Unlike most TCP congestion avoidance algorithms, FAST TCP is protected by several patents. Instead of seeking standardization by the IETF, the inventors of FAST, notably Steven H. Low and Cheng Jin, are seeking to commercialize it through the company