RFC 1263 (rfc1263) - Page 1 of 19

TCP Extensions Considered Harmful

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Network Working Group                                        S. O'Malley
Request for Comments: 1263                                   L. Peterson
                                                   University of Arizona
                                                            October 1991


                   TCP EXTENSIONS CONSIDERED HARMFUL


Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this document is
   unlimited.

Abstract

   This RFC comments on recent proposals to extend TCP.  It argues that
   the backward compatible extensions proposed in RFC's 1072 and 1185
   should not be pursued, and proposes an alternative way to evolve the
   Internet protocol suite.  Its purpose is to stimulate discussion in
   the Internet community.

1.  Introduction

   The rapid growth of the size, capacity, and complexity of the
   Internet has led to the need to change the existing protocol suite.
   For example, the maximum TCP window size is no longer sufficient to
   efficiently support the high capacity links currently being planned
   and constructed. One is then faced with the choice of either leaving
   the protocol alone and accepting the fact that TCP will run no faster
   on high capacity links than on low capacity links, or changing TCP.
   This is not an isolated incident. We have counted at least eight
   other proposed changes to TCP (some to be taken more seriously than
   others), and the question is not whether to change the protocol
   suite, but what is the most cost effective way to change it.

   This RFC compares the costs and benefits of three approaches to
   making these changes: the creation of new protocols, backward
   compatible protocol extensions, and protocol evolution. The next
   section introduces these three approaches and enumerates the
   strengths and weaknesses of each.  The following section describes
   how we believe these three approaches are best applied to the many
   proposed changes to TCP. Note that we have not written this RFC as an
   academic exercise.  It is our intent to argue against acceptance of
   the various TCP extensions, most notably RFC's 1072 and 1185 [4,5],
   by describing a more palatable alternative.




O'Malley & Peterson
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