RFC 1185 (rfc1185) - Page 1 of 21
TCP Extension for High-Speed Paths
Alternative Format: Original Text Document
Network Working Group V. Jacobson
Request for Comments: 1185 LBL
R. Braden
ISI
L. Zhang
PARC
October 1990
TCP Extension for High-Speed Paths
Status of This Memo
This memo describes an Experimental Protocol extension to TCP for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "IAB
Official Protocol Standards" for the standardization state and status
of this protocol. Distribution of this memo is unlimited.
Summary
This memo describes a small extension to TCP to support reliable
operation over very high-speed paths, using sender timestamps
transmitted using the TCP Echo option proposed in RFC-1072.
1. INTRODUCTION
TCP uses positive acknowledgments and retransmissions to provide
reliable end-to-end delivery over a full-duplex virtual circuit
called a connection [Postel81]. A connection is defined by its two
end points; each end point is a "socket", i.e., a (host,port) pair.
To protect against data corruption, TCP uses an end-to-end checksum.
Duplication and reordering are handled using a fine-grained sequence
number space, with each octet receiving a distinct sequence number.
The TCP protocol [Postel81] was designed to operate reliably over
almost any transmission medium regardless of transmission rate,
delay, corruption, duplication, or reordering of segments. In
practice, proper TCP implementations have demonstrated remarkable
robustness in adapting to a wide range of network characteristics.
For example, TCP implementations currently adapt to transfer rates in
the range of 100 bps to 10**7 bps and round-trip delays in the range
1 ms to 100 seconds.
However, the introduction of fiber optics is resulting in ever-higher
transmission speeds, and the fastest paths are moving out of the
domain for which TCP was originally engineered. This memo and RFC-
1072 [Jacobson88] propose modest extensions to TCP to extend the
Jacobson, Braden & Zhang