Parameter γ conditions for stability of FAST TCP

The stability of FAST TCP in a single-link single-source is studied in this paper. A continuous time fluid flow model of the link buffer is considered to build a linear control system model related to FAST TCP. Linearing the fluid flow model and window control model, Laplace transform version of the equations are presented. It results in a negative feedback system with open loop transfer function. With the analysis of Nyquist curve of the system, a sufficient condition on asymptotical stability of FAST TCP congestion window related to the parameter is obtained. Packet level ns2 simulations are used to verify the theoretical claims.