TCP friendly fairness in Differentiated Services IP networks

The Differentiated Services architecture has been proposed by IETF to implement QoS in IP networks. However, research shows that there exists great unfairness in the DiffServ network, especially between responsive and unresponsive aggregate traffic. This paper argues that responsive and unresponsive flows should be treated differently only to their out-of-profile traffic, in addition, traffic responsiveness should be identified by its behavior rather than simply by protocol. Then this paper defines the TCP-friendly fairness in the DiffServ network by introducing the idea of TCP friendliness into the DiffServ network to guarantee the fairness between responsive and unresponsive aggregate flows. Moreover, two markers, srTCM and trTCM, with eight mapping schemes, are examined by elaborate simulations, however, none could achieve the TCP-friendly fairness. Therefore, this paper propose the direct congestion control scheme (DCCS) to achieve fairness between responsive and unresponsive aggregate flows.