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Reusing the IPv4 Identification Field in Atomic Packets
draft-briscoe-intarea-ipv4-id-reuse-04

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Last updated: 2014-02-14
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Internet Area Working Group                                   B. Briscoe
Internet-Draft                                                        BT
Updates: 791, 2003, 2780, 4301, 4727,                  February 14, 2014
6864 (if approved)
Intended status: Standards Track
Expires: August 18, 2014

        Reusing the IPv4 Identification Field in Atomic Packets
                 draft-briscoe-intarea-ipv4-id-reuse-04

Abstract

   This specification takes a new approach to extensibility that is both
   principled and a hack.  It builds on recent moves to formalise the
   increasingly common practice where fragmentation in IPv4 more closely
   matches that of IPv6.  The large majority of IPv4 packets are now
   'atomic', meaning indivisible.  In such packets, the 16 bits of the
   IPv4 Identification (IPv4 ID) field are redundant and could be freed
   up for the Internet community to put to other uses, at least within
   the constraints imposed by their original use for reassembly.  This
   specification defines the process for redefining the semantics of
   these bits.  It uses the previously reserved control flag in the IPv4
   header to indicate that these 16 bits have new semantics.  Great care
   is taken throughout to ease incremental deployment, even in the
   presence of middleboxes that incorrectly discard or normalise packets
   that have the reserved control flag set.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 18, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the

Briscoe                  Expires August 18, 2014                [Page 1]
Internet-Draft          Reusing the IPv4 ID Field          February 2014

   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  IPv4 Wire Protocol Semantics for Reusing the
       Identification Field . . . . . . . . . . . . . . . . . . . . .  5
   4.  Behaviour of Intermediate Nodes  . . . . . . . . . . . . . . .  8
     4.1.  End-to-End Preservation of ID-Reuse Semantics  . . . . . .  8
     4.2.  Tunnel Behaviour . . . . . . . . . . . . . . . . . . . . .  8
   5.  Process for Defining Subdivisions of the ID-Reuse Field  . . .  9
     5.1.  Constraints on Uses of the ID-Reuse Field  . . . . . . . . 10
     5.2.  Process Example  . . . . . . . . . . . . . . . . . . . . . 11
   6.  Incremental Deployment of New Uses of the IPv4 ID Field  . . . 13
     6.2.  Process for Using the ID-Reuse Field Without Requiring
           RC=1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
   7.  Updates to Existing RFCs . . . . . . . . . . . . . . . . . . . 17
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 18
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   10. Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . . 20
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   12. Outstanding Issues (to be removed when all resolved) . . . . . 21
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     13.1. Normative References . . . . . . . . . . . . . . . . . . . 21
     13.2. Informative References . . . . . . . . . . . . . . . . . . 21
   Appendix A.  Why More Bits Cannot be Freed (To be Removed by
                RFC Editor) . . . . . . . . . . . . . . . . . . . . . 22
   Appendix B.  Experimental or Standards Track? (To Be Removed
                Before Publication) . . . . . . . . . . . . . . . . . 23

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