Removing exponential backoff from TCP

The well-accepted wisdom is that TCP's exponential backoff mechanism, introduced by Jacobson 20 years ago, is essential for preserving the stability of the Internet. In this paper, we show that removing exponential backoff from TCP altogether can be done without inducing any stability sideeffects. We introduce the implicit packet conservation principle and show that as long as the endpoints uphold this principle, they can only improve their end-to-end performance relative to the exponential backoff case. By conducting large-scale simulations, modeling, and network experiments in Emulab and the Internet using a kernellevel FreeBSD TCP implementation, realistic traffic distributions, and complex network topologies, we demonstrate that TCP's binary exponential backoff mechanism can be safely removed. Moreover, we show that insuitability of TCP's exponential backoff is fundamental, i.e., independent from the currently-dominant Internet traffic properties or bottleneck capac...

• Type: Journal
• Year: 2008
• Where: CCR
• Authors: Amit Mondal, Aleksandar Kuzmanovic
• Keywords: CCR 2008, Exponential Backoff, Implicit Packet Conservation, Packet Conservation Principle