64-bit Sequence Numbers for TCP
draft-looney-tcpm-64-bit-seqnos-00

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Last updated 2017-03-13
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TCP Maintenance & Minor Extensions (tcpm)                      J. Looney
Internet-Draft                                                   Netflix
Updates: 793, 2018, 5925, 7323 (if                        March 13, 2017
         approved)
Intended status: Standards Track
Expires: September 14, 2017

                    64-bit Sequence Numbers for TCP
                   draft-looney-tcpm-64-bit-seqnos-00

Abstract

   This draft updates RFC 793 to allow the optional use of 64-bit
   sequence numbers.  It also updates other standards to support the
   extended sequence number space.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on September 14, 2017.

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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Looney                 Expires September 14, 2017               [Page 1]
Internet-Draft       64-bit Sequence Numbers for TCP          March 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Design Goals  . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Overview of Implementation  . . . . . . . . . . . . . . .   3
     1.3.  Backwards Compatibility . . . . . . . . . . . . . . . . .   4
     1.4.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Extended Sequence Numbers . . . . . . . . . . . . . . . . . .   4
     2.1.  The 64-bit Sequence Number Option . . . . . . . . . . . .   5
     2.2.  Operation of the 64-bit Sequence Number Option  . . . . .   6
       2.2.1.  Choice of Initial Sequence Numbers  . . . . . . . . .   6
       2.2.2.  Negotiation of the 64-bit Sequence Number Option  . .   7
       2.2.3.  Detecting Middle Boxes  . . . . . . . . . . . . . . .   8
       2.2.4.  Backwards Compatibility Mode  . . . . . . . . . . . .   8
   3.  Changes to Other Features . . . . . . . . . . . . . . . . . .   9
     3.1.  Window Size . . . . . . . . . . . . . . . . . . . . . . .   9
     3.2.  SACK Blocks . . . . . . . . . . . . . . . . . . . . . . .   9
       3.2.1.  32-bit SACK Blocks  . . . . . . . . . . . . . . . . .   9
       3.2.2.  64-bit SACK Blocks  . . . . . . . . . . . . . . . . .  10
     3.3.  TCP Authentication Option . . . . . . . . . . . . . . . .  11
     3.4.  Other Features  . . . . . . . . . . . . . . . . . . . . .  12
   4.  Implementation Considerations . . . . . . . . . . . . . . . .  12
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
     7.1.  Attacks Due to Sequence-Number Guessing . . . . . . . . .  14
     7.2.  Downgrade Attacks . . . . . . . . . . . . . . . . . . . .  14
     7.3.  Denial-of-Service Attacks . . . . . . . . . . . . . . . .  15
     7.4.  32-bit Sequence Numbers . . . . . . . . . . . . . . . . .  15
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Appendix A.  Design Choices . . . . . . . . . . . . . . . . . . .  16
     A.1.  Detecting Middle Boxes  . . . . . . . . . . . . . . . . .  16
     A.2.  SACK Blocks . . . . . . . . . . . . . . . . . . . . . . .  17
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   RFC 793 [RFC0793] specifies the sequence number space as a 32-bit
   space.  This means that the sequence number space will wrap in 2**32
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