TCP Extensions Considered Harmful (RFC1263)
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
S. O'Malley: AUTHOR [+2]
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.
Network Working Group S. O'Malley
Request for Comments: 1263 L. Peterson
University of Arizona
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
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.
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.
2. Creation vs. Extension vs. Evolution
2.1. Protocol Creation
Protocol creation involves the design, implementation,
standardization, and distribution of an entirely new protocol. In
this context, there are two basic reasons for creating a new
protocol. The first is to replace an old protocol that is so outdated
that it can no longer be effectively extended to perform its original