Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
RFC 5214

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Network Working Group                                         F. Templin
Request for Comments: 5214                          Boeing Phantom Works
Obsoletes: 4214                                               T. Gleeson
Category: Informational                               Cisco Systems K.K.
                                                               D. Thaler
                                                   Microsoft Corporation
                                                              March 2008

        Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

IESG Note

   The IESG thinks that this work is related to IETF work done in WG
   softwires, but this does not prevent publishing.

Abstract

   The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects
   dual-stack (IPv6/IPv4) nodes over IPv4 networks.  ISATAP views the
   IPv4 network as a link layer for IPv6 and supports an automatic
   tunneling abstraction similar to the Non-Broadcast Multiple Access
   (NBMA) model.

Templin, et al.              Informational                      [Page 1]
RFC 5214                         ISATAP                       March 2008

Table of Contents

   1. Introduction ....................................................2
   2. Requirements ....................................................3
   3. Terminology .....................................................3
   4. Domain of Applicability .........................................4
   5. Node Requirements ...............................................4
   6. Addressing Requirements .........................................4
      6.1. ISATAP Interface Identifiers ...............................4
      6.2. ISATAP Interface Address Configuration .....................5
      6.3. Multicast/Anycast ..........................................5
   7. Automatic Tunneling .............................................5
      7.1. Encapsulation ..............................................5
      7.2. Handling ICMPv4 Errors .....................................5
      7.3. Decapsulation ..............................................6
      7.4. Link-Local Addresses .......................................6
      7.5. Neighbor Discovery over Tunnels ............................6
   8. Neighbor Discovery for ISATAP Interfaces ........................6
      8.1. Conceptual Model of a Host .................................7
      8.2. Router and Prefix Discovery - Router Specification .........7
      8.3. Router and Prefix Discovery - Host Specification ...........7
           8.3.1. Host Variables ......................................7
           8.3.2. Potential Router List Initialization ................7
           8.3.3. Processing Received Router Advertisements ...........8
           8.3.4. Sending Router Solicitations ........................8
      8.4. Neighbor Unreachability Detection ..........................9
   9. Site Administration Considerations ..............................9
   10. Security Considerations ........................................9
   11. IANA Considerations ...........................................10
   12. Acknowledgments ...............................................10
   13. References ....................................................11
      13.1. Normative References .....................................11
      13.2. Informative References ...................................12
   Appendix A. Modified EUI-64 Addresses in the IANA Ethernet
             Address Block ...........................................13

1.  Introduction

   This document specifies a simple mechanism called the Intra-Site
   Automatic Tunnel Addressing Protocol (ISATAP) that connects
   dual-stack (IPv6/IPv4) nodes over IPv4 networks.  Dual-stack nodes
   use ISATAP to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP
   views the IPv4 network as a link layer for IPv6.

   ISATAP enables automatic tunneling whether global or private IPv4
   addresses are used, and it presents a Non-Broadcast Multiple Access
   (NBMA) abstraction similar to [RFC2491],[RFC2492],[RFC2529], and
   [RFC3056].

Templin, et al.              Informational                      [Page 2]
RFC 5214                         ISATAP                       March 2008

   The main objectives of this document are to: 1) describe the domain
   of applicability, 2) specify addressing requirements, 3) specify
   automatic tunneling using ISATAP, 4) specify the operation of IPv6
   Neighbor Discovery over ISATAP interfaces, and 5) discuss Site
   Administration, Security, and IANA considerations.

2.  Requirements

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this