Transmission of IPv4 Packets over Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) Interfaces
RFC 5579

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Independent Submission                                   F. Templin, Ed.
Request for Comments: 5579                  Boeing Research & Technology
Category: Informational                                    February 2010
ISSN: 2070-1721

                   Transmission of IPv4 Packets over
  Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) Interfaces

Abstract

   The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
   specifies a Non-Broadcast, Multiple Access (NBMA) interface type for
   the transmission of IPv6 packets over IPv4 networks using automatic
   IPv6-in-IPv4 encapsulation.  The original specifications make no
   provisions for the encapsulation and transmission of IPv4 packets,
   however.  This document specifies a method for transmitting IPv4
   packets over ISATAP interfaces.

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/rfc5579.

IESG Note

   This RFC is not a candidate for any level of Internet Standard.  The
   IETF disclaims any knowledge of the fitness of this RFC for any
   purpose and in particular notes that the decision to publish is not
   based on IETF review for such things as security, congestion control,
   or inappropriate interaction with deployed protocols.  The RFC Editor
   has chosen to publish this document at its discretion.  Readers of
   this document should exercise caution in evaluating its value for
   implementation and deployment.  See RFC 3932 for more information.

Templin                       Informational                     [Page 1]
RFC 5579                IPv4 Packets over ISATAP           February 2010

Copyright Notice

   Copyright (c) 2010 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
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. ISATAP Interface Model ..........................................3
   4. ISATAP Interface MTU ............................................4
   5. IPv6 Operation ..................................................4
   6. IPv4 Operation ..................................................4
      6.1. ISATAP IPv4 Address Configuration ..........................4
      6.2. IPv4 Route Configuration ...................................5
      6.3. ISATAP Interface Determination .............................5
      6.4. Next-Hop Resolution ........................................5
      6.5. Encapsulation and Transmission .............................6
      6.6. IPv4 Multicast Mapping .....................................6
      6.7. Recursive Encapsulation Avoidance ..........................7
   7. Security Considerations .........................................7
   8. Acknowledgements ................................................7
   9. References ......................................................7
      9.1. Normative References .......................................7
      9.2. Informative References .....................................8
   Appendix A. Encapsulation Avoidance ................................9

Templin                       Informational                     [Page 2]
RFC 5579                IPv4 Packets over ISATAP           February 2010

1.  Introduction

   The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
   [RFC5214] specifies a Non-Broadcast, Multiple Access (NBMA) interface
   type for the transmission of IPv6 packets over IPv4 networks using
   automatic IPv6-in-IPv4 encapsulation.  ISATAP interfaces therefore
   typically configure IPv6 addresses and prefixes, but they do not
   configure IPv4 addresses and prefixes.  In typical implementations
   and deployments, an ISATAP interface therefore appears as an ordinary
   interface configured for IPv6 operation but with a null IPv4
   configuration.  This places an unnecessary limitation on the ISATAP
   domain of applicability.

   ISATAP interfaces perform automatic IPv6-in-IPv4 encapsulation over a