ON THE ANALYSIS OF PARAMETER γIN FAST TCP

The limits of parameter γ in FAST TCP are studied in this paper. A continuous time fluid flow model of the link buffer is considered to create a linear control system related to FAST TCP.Linearing the fluid flow model and window control model, the Laplace transform version of congestion control system 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 γ is obtained. Packet level ns-2 simulations are used to verify the theoretical claims.