Aaron Falk - 4/15/04
USC ISI-West

The eXplicit Control Protocol: An Introduction with Measured Data

TCP is the basic end-to-end transport protocol of the Internet, and its congestion control algorithm is fundamental to efficient,high-performance, and stable network operation. The TCP congestion control algorithm (published by Van Jacobson in 1988) has been highly successful over many orders of magnitude in Internet growth, but recently it has begun to reach its limits. Gigabit file transfers, lossy wireless links, and high latency connections are all driving TCP congestion control outside of its natural operating regime.

The eXplicit Control Protocol (XCP), first published by MIT's Dina Katabi in 2002, represents a major advance in Internet congestion control. XCP delivers the highest possible application performance over a broad range of network infrastructure, including extremely high speed and very high delay links that are not well served by TCP. XCP is novel in separating the efficiency and fairness policies of congestion control, enabling routers to quickly make use of available bandwidth while conservatively managing the allocation of bandwidth to flows. XCP is built upon a new principle: carrying per-flow congestion state in packets.

This talk describes the XCP algorithm, the development effort at ISI, and some preliminary measured results of the ISI XCP implementation.