Explicit TCP Rate Shaping: Architecture and Applications

Abstract

The emergence of new applications, the increasing differences in bandwidth between intra-nets and the Internet, and the introduction of Quality of Service differentiation has changed the requirements for the underlying Transport Control Protocol TCP. This paper uses two types of applications to demonstrate weaknesses of TCP that can lead to a degradation of network service in the perception of a user/application: Streaming applications often use HTTP/TCP to avoid blocking by firewalls. Instead of a high throughput these applications depend on small packet loss rates and reduced jitter to play out frames in real time. We show that regular TCP does not allow these applications to perform well. Bulk TCP data transfer in intra-nets can cause the throughput to drop significantly if socket buffers are not chosen carefully and differently from connections over long fat pipes. In both cases the window based flow control of TCP constantly tries to probe for the maximum bandwidth available, whic..