We all know what happens if we pour water too quickly into a
funnel. We quickly find ourselves on the floor with a roll of
paper towels cleaning up the mess. This is the problem Van
Jacobson helped solve in the late 1980s. Instead of water,
consider the flow of data. The problem was traffic congestion on
the Internet. The original TCP/IP worked fine on the campus,
connecting various hosts like computers and shared resources
such as printers and plotters. But when those local networks,
often operating at 10MB, were connected with other local
networks via the long distance lines of the day, often operating
at 56kb, the result was a traffic jam and a lot of frustrated
users. You can see the funnel effect in a graphic taken from
Congestion Avoidance and Control, a paper written in 1988 by
Jacobson, then at Lawrence Berkeley Laboratory, and Michael J.
Karels of the University of California at Berkeley. As Jacobson
explains it, the problem was that the error correction and
repair facilities built into TCP/IP were n