Stability and bifurcation analysis in a FAST TCP model with feedback delay

This paper focuses on the local stability of a FAST TCP model of Internet congestion control algorithms. Necessary and sufficient stability conditions in terms of key system parameters are given, which can provide exact guideline for setting system parameters. In addition, the complex dynamics of the system is also addressed. We demonstrate that Hopf bifurcation would occur when the gain parameter alpha is less than a critical value. Furthermore, the direction and the stability of the bifurcating periodic solutions are determined by applying the normal form theory and the center manifold theorem. Finally, some numerical examples are given to verify the theoretical analysis.