RFC 1106 (rfc1106) - Page 1 of 13

TCP big window and NAK options

Network Working Group                                             R. Fox
Request for Comments:  1106                                       Tandem
                                                               June 1989


                     TCP Big Window and Nak Options

Status of this Memo

   This memo discusses two extensions to the TCP protocol to provide a
   more efficient operation over a network with a high bandwidth*delay
   product.  The extensions described in this document have been
   implemented and shown to work using resources at NASA.  This memo
   describes an Experimental Protocol, these extensions are not proposed
   as an Internet standard, but as a starting point for further
   research.  Distribution of this memo is unlimited.

Abstract

   Two extensions to the TCP protocol are described in this RFC in order
   to provide a more efficient operation over a network with a high
   bandwidth*delay product.  The main issue that still needs to be
   solved is congestion versus noise.  This issue is touched on in this
   memo, but further research is still needed on the applicability of
   the extensions in the Internet as a whole infrastructure and not just
   high bandwidth*delay product networks.  Even with this outstanding
   issue, this document does describe the use of these options in the
   isolated satellite network environment to help facilitate more
   efficient use of this special medium to help off load bulk data
   transfers from links needed for interactive use.

1.  Introduction

   Recent work on TCP has shown great performance gains over a variety
   of network paths [1].  However, these changes still do not work well
   over network paths that have a large round trip delay (satellite with
   a 600 ms round trip delay) or a very large bandwidth
   (transcontinental DS3 line).  These two networks exhibit a higher
   bandwidth*delay product, over 10**6 bits, than the 10**5 bits that
   TCP is currently limited to.  This high bandwidth*delay product
   refers to the amount of data that may be unacknowledged so that all
   of the networks bandwidth is being utilized by TCP.  This may also be
   referred to as "filling the pipe" [2] so that the sender of data can
   always put data onto the network and the receiver will always have
   something to read, and neither end of the connection will be forced
   to wait for the other end.

   After the last batch of algorithm improvements to TCP, performance



Fox