A Comparison of IPv6-over-IPv4 Tunnel Mechanisms
RFC 7059

Independent Submission                                       S. Steffann
Request for Comments: 7059                   S.J.M. Steffann Consultancy
Category: Informational                                   I. van Beijnum
ISSN: 2070-1721                                 Institute IMDEA Networks
                                                             R. van Rein
                                                            OpenFortress
                                                           November 2013

            A Comparison of IPv6-over-IPv4 Tunnel Mechanisms

Abstract

   This document provides an overview of various ways to tunnel IPv6
   packets over IPv4 networks.  It covers mechanisms in current use,
   touches on several mechanisms that are now only of historic interest,
   and discusses some newer tunnel mechanisms that are not widely used
   at the time of publication.  The goal of the document is helping
   people with an IPv6-in-IPv4 tunneling need to select the mechanisms
   that may apply to them.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7059.

Copyright Notice

   Copyright (c) 2013 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
   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
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   to this document.

Steffann, et al.              Informational                     [Page 1]
RFC 7059                      IPv6 Tunnels                 November 2013

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Tunnel Mechanisms  . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Configured Tunnels (Manual Tunnels / 6in4) . . . . . . . .  7
     3.2.  Automatic Tunneling  . . . . . . . . . . . . . . . . . . .  8
     3.3.  IPv6 over IPv4 without Explicit Tunnels (6over4) . . . . .  9
     3.4.  Generic Routing Encapsulation (GRE)  . . . . . . . . . . . 10
     3.5.  Connection of IPv6 Domains via IPv4 Clouds (6to4)  . . . . 10
       3.5.1.  6to4 Provider Managed Tunnels  . . . . . . . . . . . . 11
     3.6.  Anything In Anything (AYIYA) . . . . . . . . . . . . . . . 12
     3.7.  Intra-Site Automatic Tunnel Addressing (ISATAP)  . . . . . 13
     3.8.  Tunneling IPv6 over UDP through NATs (Teredo)  . . . . . . 14
     3.9.  IPv6 Rapid Deployment (6rd)  . . . . . . . . . . . . . . . 15
     3.10. Native IPv6 behind NAT44 CPEs (6a44) . . . . . . . . . . . 16
     3.11. Locator/ID Separation Protocol (LISP)  . . . . . . . . . . 16
     3.12. Subnetwork Encapsulation and Adaptation Layer (SEAL) . . . 18
     3.13. Peer-to-Peer IPv6 on Any Internetwork (6bed4)  . . . . . . 19
   4.  Related Protocols  . . . . . . . . . . . . . . . . . . . . . . 20
     4.1.  Tunnel Setup Protocol (TSP)  . . . . . . . . . . . . . . . 20
     4.2.  SixXS Heartbeat Protocol . . . . . . . . . . . . . . . . . 20
     4.3.  Tunnel Information and Control Protocol (TIC)  . . . . . . 21
   5.  Common Aspects . . . . . . . . . . . . . . . . . . . . . . . . 22
     5.1.  Protocol 41 Encapsulation  . . . . . . . . . . . . . . . . 22
     5.2.  NAT and Firewalls  . . . . . . . . . . . . . . . . . . . . 22
     5.3.  MTU Considerations . . . . . . . . . . . . . . . . . . . . 24
     5.4.  IPv4 Addresses Embedded in IPv6 Addresses  . . . . . . . . 25
   6.  Evaluation of Tunnel Mechanisms  . . . . . . . . . . . . . . . 28
     6.1.  Efficiency of IPv4 Address Use . . . . . . . . . . . . . . 28
     6.2.  Supported Network Topologies . . . . . . . . . . . . . . . 29
     6.3.  Robustness . . . . . . . . . . . . . . . . . . . . . . . . 30
     6.4.  Gateway State  . . . . . . . . . . . . . . . . . . . . . . 32
     6.5.  Performance  . . . . . . . . . . . . . . . . . . . . . . . 33
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 34
   8.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 35
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35