RFC 1349 (rfc1349) - Page 1 of 28

Type of Service in the Internet Protocol Suite

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Network Working Group                                        P. Almquist
Request for Comments: 1349                                    Consultant
Updates: RFCs 1248, 1247, 1195,                                July 1992
         1123, 1122, 1060, 791




             Type of Service in the Internet Protocol Suite

Status of This Memo

   This document specifies an IAB standards track protocol 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 changes and clarifies some aspects of the semantics of the
   Type of Service octet in the Internet Protocol (IP) header.  The
   handling of IP Type of Service by both hosts and routers is specified
   in some detail.

   This memo defines a new TOS value for requesting that the network
   minimize the monetary cost of transmitting a datagram.  A number of
   additional new TOS values are reserved for future experimentation and
   standardization.  The ability to request that transmission be
   optimized along multiple axes (previously accomplished by setting
   multiple TOS bits simultaneously) is removed.  Thus, for example, a
   single datagram can no longer request that the network simultaneously
   minimize delay and maximize throughput.

   In addition, there is a minor conflict between the Host Requirements
   (RFC-1122 and RFC-1123) and a number of other standards concerning
   the sizes of the fields in the Type of Service octet.  This memo
   resolves that conflict.

Table of Contents

   1.  Introduction ...............................................    3

   2.  Goals and Philosophy .......................................    3

   3.  Specification of the Type of Service Octet .................    4

   4.  Specification of the TOS Field .............................    5



Almquist
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