摘要：I n looking back over some 30 years of experience with the Internet,
the critical component of the Internet Protocol Suite that has
been the foundation of its success as the technology of choice for
the global communications system is the Internet Protocol (IP) itself,
working an overlay protocol that can span almost any form of communications
media. But I would also like to nominate another contender
for a critical role within IP, namely the reliable transport protocol that
sits on top of IP, the Transmission Control Protocol (TCP), and its
evolution over time. In support of this nomination is the fact that the
end-to-end rate-adaptive control algorithm that was adopted by TCP
represented a truly radical shift from the reliable gateway-to-gateway
virtual circuit flow control systems used by other protocols of similar
vintage. It is also interesting to note that TCP is not designed to operate
at any particular speed, but it attempts to operate at a speed that
uses its fair share of all available network capacity along the network
path. The fundamental property of the TCP flow control algorithm is
that it attempts to be maximally efficient while also attempting to be
maximally fair.
