In-Flight IPv6 Extension Header Insertion Considered Harmful
draft-smith-6man-in-flight-eh-insertion-harmful-00

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Internet Engineering Task Force                                 M. Smith
Internet-Draft                                           October 8, 2019
Intended status: Best Current Practice
Expires: April 10, 2020

      In-Flight IPv6 Extension Header Insertion Considered Harmful
           draft-smith-6man-in-flight-eh-insertion-harmful-00

Abstract

   In the past few years, as well as currently, there have and are a
   number of proposals to insert IPv6 Extension Headers into existing
   IPv6 packets while in flight.  This contradicts explicit prohibition
   of this type of IPv6 packet proccessing in the IPv6 standard.  This
   memo describes the possible failures that can occur with EH
   insertion, the harm they can cause, and the existing model that is
   and should continue to be used to add new information to an existing
   IPv6 and other packets.

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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   This Internet-Draft will expire on April 10, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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Smith                    Expires April 10, 2020                 [Page 1]
Internet-Draft     In-Flight IPv6 EH Insertion Harmful      October 2019

   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  In-Flight Extension Header Insertion Defined  . . . . . . . .   3
     3.1.  In-Flight Insertion . . . . . . . . . . . . . . . . . . .   3
     3.2.  In-Flight Removal . . . . . . . . . . . . . . . . . . . .   3
   4.  EH Removal Failure Causes . . . . . . . . . . . . . . . . . .   4
     4.1.  Implementation Bugs . . . . . . . . . . . . . . . . . . .   4
     4.2.  Partial Node Failure  . . . . . . . . . . . . . . . . . .   4
     4.3.  Operator Configuration Error  . . . . . . . . . . . . . .   4
   5.  Single Point of Failure . . . . . . . . . . . . . . . . . . .   5
   6.  MUST Remove is Aspirational . . . . . . . . . . . . . . . . .   5
   7.  Harm  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Violates RFC8200 and All Of Its Ancestors.  . . . . . . .   5
     7.2.  Ignores Source Address Field Semantics  . . . . . . . . .   5
     7.3.  Breaks ICMPv6 . . . . . . . . . . . . . . . . . . . . . .   5
       7.3.1.  Breaks PMTUD  . . . . . . . . . . . . . . . . . . . .   5
     7.4.  Breaks IPsec  . . . . . . . . . . . . . . . . . . . . . .   6
     7.5.  May Confuse Destination Node  . . . . . . . . . . . . . .   6
     7.6.  May Cause Faults in Subsequent Transit Networks . . . . .   6
     7.7.  Implementation Complexity . . . . . . . . . . . . . . . .   6
   8.  Be conservative in what you send, ... . . . . . . . . . . . .   7
   9.  Solution: Encapsulation . . . . . . . . . . . . . . . . . . .   7
     9.1.  IPv6 Tunnelling . . . . . . . . . . . . . . . . . . . . .   8
     9.2.  MPLS  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   10. In-Flight Insertion Considered Harmful  . . . . . . . . . . .   9
   11. Security Considerations . . . . . . . . . . . . . . . . . . .   9
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   13. Change Log [RFC Editor please remove] . . . . . . . . . . . .   9
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     14.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     14.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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