NAT64 Tunnel Protocol
draft-dupont-6man-nat64tp-02

Document Type Active Internet-Draft (individual)
Author Kasper Dupont 
Last updated 2020-11-29
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Network Working Group                                          K. Dupont
Internet-Draft                                         November 29, 2020
Intended status: Standards Track
Expires: June 2, 2021

                         NAT64 Tunnel Protocol
                      draft-dupont-6man-nat64tp-02

Abstract

   This document describes a stateless NAT64 extension which allows for
   creation of reliable tunnels between islands of IPv6 deployment.

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 June 2, 2021.

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   Copyright (c) 2020 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Communication model . . . . . . . . . . . . . . . . . . . . .   3
   4.  Protocol operation  . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  NAT64 outgoing operation  . . . . . . . . . . . . . . . .   4
     4.2.  NAT64 incoming operation  . . . . . . . . . . . . . . . .   5
     4.3.  NAT64TP endpoint operation  . . . . . . . . . . . . . . .   5
     4.4.  Intermediate network node operation . . . . . . . . . . .   7
   5.  Deployability . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Sunsetting IPv4 . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Prior protocols for connecting islands of IPv6 through tunnels over
   IPv4 exist including [RFC3056].  However since the introduction of
   those protocols NAT has gained widespread use and a majority of ISPs
   still have not started deploying IPv6.  For those reasons there is a
   need for a new way of connecting islands of IPv6.

   NAT64 as defined in [RFC6146] is a method for translating between
   IPv6 and IPv4.  This is intended to allow IPv6-only clients to reach
   IPv4-only services.  NAT64 also happens to be very useful for
   connecting islands of IPv6 to an IPv4-only ISP.  Moreover high
   availability can easily be achieved by connecting an island of IPv6
   through redundant NAT64 gateways to multiple ISPs.

   Many prior tunnel protocols fail to work reliably when one endpoint
   of the tunnel is behind NAT.  And none of them work reliably when
   both endpoints are behind NAT64.

   [RFC6146] specifies support for use of UDP, TCP, and ICMP.  Of those
   only UDP is suitable for building a tunnel protocol.  But when both
   endpoints are connecting through NAT the use of hole punching will be
   necessary.  And in many NAT setups, especially those using multiple
   layers of NAT, the use of hole punching is unreliable.  Even when
   these work they rely on state in each NAT device in order to maintain
   a connection.

   This document defines NAT64TP (the NAT64 Tunnel Protocol).  NAT64TP
   is a simple stateless NAT64 extension which allows tunnel protocols

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   to reliably establish connections between islands of IPv6.  NAT64TP
   achieves this by using UDP packets in which each packet carries
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