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INTERNET-DRAFT                                           Fred L. Templin
                                                       SRI International
                                                       17 May 2001

        Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

                            Copyright Notice

                    Placeholder for ISOC copyright.

                    draft-ietf-ngtrans-isatap-01.txt

Abstract

   This document specifies an intra-site automatic tunneling protocol
   (ISATAP) for connecting IPv6 hosts and routers (nodes) within
   predominantly IPv4-based networks. This method is based on an IPv6
   aggregatable global unicast address format (described herein) that
   embeds the IPv4 address of a node within the EUI-64 format interface
   identifier.  This document assumes that, during the IPv4 to IPv6 co-
   existence and transition phase, many sites will deploy IPv6
   incrementally within their IPv4 interior routing domains; especially
   those sites which have large and complex pre-existing IPv4
   infrastructures. Within such sites, the address format and methods
   described in this document will enable IPv6 deployment for nodes that
   do not share a common data link with an IPv6 gateway for their site.

   While other works in progress in the NGTRANS working group propose
   mechanisms for assigning globally-unique IPv6 address prefixes to
   sites and methods for inter-domain routing between such sites, the
   approach outlined in this memo enables large-scale incremental
   deployment of IPv6 for nodes within a site's pre-existing IPv4
   infrastructure without incurring aggregation scaling issues at the
   border gateways nor requiring site-wide deployment of special IPv4
   services such as multicast. The approach proposed by this document
   supports IPv6 routing within both the site-local and global IPv6
   routing domains as well as automatic IPv6 in IPv4 tunneling across
   portions of a site's IPv4 infrastructure which have no native IPv6
   support. Additionally, this approach supports automatic tunneling
   within sites which use non globally-unique IPv4 address assignments,
   such as when Network Address Translation [NAT] is used.

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering



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   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet- Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


1.  Introduction

   The IETF NGTRANS working group anticipates an heterogeneous IPv4/IPv6
   infrastructure in the near future and thus is chartered to develop
   mechanisms to support IPv4/IPv6 coexistence and transition toward
   global IPv6 deployment. For the most part, existing NGTRANS
   approaches focus on inter-domain routing between IPv6 islands using
   the existing global IPv4 backbone as transit. But, these islands may
   themselves comprise complex heterogeneous IPv4/IPv6 networks (e.g.
   large academic or commercial campus intranets) that require intra-
   domain IPv4 to IPv6 transition mechanisms and strategies as well. In
   order to address this requirement, this document presents a simple
   and scalable approach that enables incremental deployment of IPv6
   nodes within predominantly IPv4-based intranets. We refer to this
   approach as the Intra-Site Automatic Tunnel Addressing Protocol, or
   ISATAP (pronounced: "ice-a-tap").

   The ISATAP approach is based on an aggregatable global unicast
   address format that carries a standard 64-bit IPv6 address prefix
   [ADDR][AGGR] with a specially-constructed 64-bit EUI-64 Interface
   Identifier [EUI64].  This address format is fully compatible with
   both native IPv6 and NGTRANS routing practices (e.g. [6to4],[6BONE]).
   But, the interface identifier in an ISATAP address employs a special
   construction (using the IEEE Organizationally Unique Identifier (OUI)
   reserved by the Internet Assigned Numbers Authority [IANA]) that
   encapsulates an IPv4 address suitable for automatic IPv6-in-IPv4 tun-
   neling. Since tunneling occurs only within the site-level prefix of
   the ISATAP address, the embedded IPv4 address NEED NOT be globally
   unique; rather, it need only be topologically correct for (and unique
   within) the context of the site.

   This approach allows dual-stack nodes that do not share a common



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   datalink with an IPv6 gateway to join the global IPv6 network by
   automatically tunneling IPv6 messages through the IPv4 routing
   infrastructure within their site. Two methods for automatic discovery
   of an off-link IPv6 gateway for ISATAP address autoconfiguration are
   provided. This approach allows large-scale intra-site deployment
   without incurring aggregation scaling issues at the border gateways,
   since only a single IPv6 address prefix is used for the entire site.
   Finally, this approach supports intranets which use non-globally
   unique IPv4 addresses, such as when private address allocations
   [PRIVATE] and/or Network Address Translation [NAT] are used.


2.  Changes

   Major changes from version -00 to version -01:

     - Revised draft to require *different* /64 prefixs for ISATAP
       addresses and native IPv6 addresses. Thus, a node's ISATAP
       interface is assigned a /64 prefix that is distinct from the
       prefixes assigned to any other interfaces attached to the
       node - be they physical or logical interfaces. This approach
       eliminates ISATAP-specific sending rules presented in earlier
       draft versions.

     - Changed sense of 'u/l' bit in the ISATAP address interface
       identifier to indicate "local scope", since ISATAP interface
       identifiers are unique only within the scope of the ISATAP
       prefix. (See section 4.)


   Major changes from version personal draft to NGTRANS WG version -00:

     - Title change to provide higher-level description of field of
       use addressed by this draft. Removed other extraneous text.

     - Major new section on automatic discovery of off-link IPv6 routers
       when IPv6-IPv4 compatibility addresses are used.


3.  Terminology

   The terminology of [IPv6] applies to this document. Additionally, the
   following terms are used extensively throughout this document:

   ISATAP prefix:
     Any globally aggregatable 64-bit IPv6 routing prefix (whether from a
     native IPv6 assigned numbers authority or from a special-purpose numbering
     scheme such as [6BONE][6TO4]) reserved by a local network administrator



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     specifically for ISATAP purposes. ISATAP prefixes are used to configure
     ISATAP addresses ONLY; native IPv6 addresses SHOULD NOT be configured
     using an ISATAP prefix.

   ISATAP address:
     An IPv6 address with an ISATAP prefix and having an IPv4 address
     embedded in the interface identifier in the manner described in
     section 4 below.

   ISATAP pseudo-interface:
     ISATAP encapsulation of IPv6 packets inside IPv4 packets occurs
     at a point that is logically equivalent to an IPv6 interface,
     with the link layer being the IPv4 unicast network.  This point
     is referred to as a pseudo-interface. An ISATAP pseudo-interface
     is assigned an ISATAP address through address autoconfiguration.

   ISATAP router:
     An IPv6 router supporting an ISATAP pseudo-interface. It is normally
     an interior router within an heterogeneous IPv6/IPv4 network.

   ISATAP host:
     An IPv6 host which has an ISATAP pseudo-interface.


4.  ISATAP Address Format

   In sections 4.1 and 4.2, we will motivate our proposed extensions of
   the existing IEEE OUI reserved by IANA to support IEEE EUI-64 format
   addresses.  While these proposed extensions are intended support the
   ISATAP address format, they also provide a flexible framework for
   future IANA use.  Therefore, the extensions proposed in sections 4.1
   and 4.2 may provide beneficial future use to IANA beyond the scope of
   ISATAP addresses. We present the ISATAP address format itself in sec-
   tions 4.3 and 4.4.


   4.1.  IEEE EUI-64 Interface Identifiers in IPv6 Addresses

   IPv6 aggregatable global and local-use unicast addresses [ADDR]
   include a 64-bit interface identifier in IEEE EUI-64 format [EUI64],
   which is specified as the concatenation of a 24-bit company_id value
   (also known as the OUI) assigned by the IEEE Registration Authority
   (IEEE/RAC) and a 40-bit extension identifier assigned by the address-
   ing authority for that OUI. (Normally, the addressing authority is
   the organization to which the IEEE has allocated the OUI). IEEE EUI-
   64 interface identifiers are formatted as follows:





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    |0              1|1              3|3              4|4              6|
    |0              5|6              1|2              7|8              3|
    +----------------+----------------+----------------+----------------+
    |ccccccugcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm|mmmmmmmmmmmmmmmm|
    +----------------+----------------+----------------+----------------+

   Where 'c' are the company-specific bits of the OUI, 'u' is the
   universal/local bit, 'g' is the individual/group bit and 'm' are the
   extension identifier bits. (NOTE: [ADDR] specifies that the 'u' bit
   is inverted from its normal sense in the IEEE context; therefore u=1
   indicates global scope and u=0 indicates local scope).

   In order to support encapsulation of legacy IEEE EUI-48 (24-bit)
   extension identifier values, [EUI64] specifies that the first two
   octets of the EUI-64 40-bit extension identifier (bits 24 through 39
   of the EUI-64 address itself) SHALL BE 0xFFFE if the extension iden-
   tifier encapsulates an EUI-48 value. [EUI64] further specifies that
   the first two octets of the extension identifier SHALL NOT be 0xFFFF,
   since this value is reserved by the IEEE/RAC. However, all other 40-
   bit extension identifier values are available for assignment by the
   OUI addressing authority.


   4.2.  An EUI-64 Interface Identifier Format for IANA

   The IANA owns IEEE OUI: 00-00-5E, and [IANA] specifies EUI-48 format
   (24-bit) interface identifier assignments within that OUI. But,
   [IANA] does not specify how these legacy EUI-48 assignments will be
   written in EUI-64 format, nor does it specify a format for future
   40-bit extension identifier assignments. We propose the following
   format for EUI-64 addresses within IANA's OUI reservation:


    |0                      2|2      3|3      3|4                      6|
    |0                      3|4      1|2      9|0                      3|
    +------------------------+--------+--------+------------------------+
    |  OUI ("00-00-5E"+u+g)  |  TYPE  |  TSE   |          TSD           |
    +------------------------+--------+--------+------------------------+

   Where the fields are:

      OUI     IANA's OUI: 00-00-5E with 'u' and 'g' bits (3 octets)

      TYPE    Type field; indicates how (TSE, TSD) are interpreted (1 octet)

      TSE     Type-Specific Extension (1 octet)

      TSD     Type-Specific Data (3 octets)



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   And the following interpretations are defined based on TYPE:

      TYPE         (TSE, TSD) Interpretation
      ----         -------------------------
      0x00-0xFD    RESERVED for future IANA use
      0xFE         (TSE, TSD) together contain an embedded IPv4 address
      0xFF         TSD is interpreted based on TSE as follows:

                   TSE          TSD Interpretation
                   ---          ------------------
                   0x00-0xFD    RESERVED for future IANA use
                   0xFE         TSD contains 24-bit EUI-48 intf id
                   0xFF         RESERVED by IEEE/RAC

   Essentially, if TYPE=0xFE, TSE is treated as an extension of TSD. If
   TYPE=0xFF, TSE is treated as an extension of TYPE. Other values for
   TYPE (and hence, other interpretations of TSE, TSD) are reserved for
   future IANA use. This format conforms to all requirements specified
   in [EUI64] and supports encapsulation of EUI-48 interface identifiers
   in the manner described by that document. For example, an existing
   IANA EUI-48 format multicast address such as:

       01-00-5E-01-02-03

   would be written in the IANA EUI-64 format as:

       01-00-5E-FF-FE-01-02-03

   But, this proposed format also provides a special TYPE (0xFE) for
   embedding IPv4 addresses within the IANA 40-bit extension identifier.
   This special TYPE forms the basis for the ISATAP address format as
   described in the following sections.


   4.3.  ISATAP Address Construction

   Using the proposed IANA-specific method for interface identifier con-
   struction discussed in sections 4.1 and 4.2 (with TYPE=0xFE), and
   with reference to [ADDR], we can construct an ISATAP address as fol-
   lows:

    | 3|  13 | 8 |   24   |   16   | 8 | 8 | 8 | 8 |    32 bits     |
    +--+-----+---+--------+--------+---+---+---+---+---+---+---+----+
    |FP| TLA |RES|  NLA   |  SLA   | 0x| 0x| 0x| 0x|  IPv4 Address  |
    |  | ID  |   |  ID    |  ID    | 00| 00| 5E| FE|   of Endpoint  |
    +--+-----+---+--------+--------+--------------------------------+

   (NOTE: since ISATAP address interface identifiers are interpreted



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   only within the local scope of the /64 ISATAP prefix, we set the u/l
   bit in the least significant octet of the OUI to '0' to indicate
   local scope.)

   By way of example, an existing node with IPv4 address 140.173.129.8
   might be assigned an IPv6 64-bit prefix of 3FFE:1a05:510:200::/64. We
   can then construct an ISATAP address for this node as:

      3FFE:1a05:510:200:0:5EFE:8CAD:8108

   or (perhaps more appropriately) written as the alternative form for
   an IPv6 address with embedded IPv4 address found in [ADDR]:

      3FFE:1a05:510:200:0:5EFE:140.173.129.8

   Similarly, we can construct the link-local and site-local variants
   (respectively) of the ISATAP address as:

      FE80::0:5EFE:140.173.129.8
      FEC0::200:0:5EFE:140.173.129.8


   4.4.  Advantages

   By embedding an IPv4 address in the interface identifier portion of
   an IPv6 address as described in section 4.3, we can construct aggre-
   gatable global unicast IPv6 addresses that can either be routed glo-
   bally via the IPv6 infrastructure or automatically tunneled locally
   across portions of a site's IPv4 infrastructure which have no native
   IPv6 support.  Additionally, a node with an ISATAP address could act
   as a gateway for nodes with native IPv6 addresses with which it
   shares a common physical link, since the ISATAP node could automati-
   cally tunnel messages across a site's IPv4 domain on behalf of the
   native IPv6 nodes.  An example would be deployment of IPv6 on some
   subset of the hosts attached to a workgroup's LAN. In this case, one
   host could configure an ISATAP address and act as a gateway for other
   hosts on the LAN which use native IPv6 addresses.

   An additional advantage for our proposed method of embedding an IPv4
   address in the interface identifier portion of an IPv6 address not
   found in other approaches such as [6TO4] is that large numbers of
   ISATAP addresses could be assigned within a common IPv6 routing pre-
   fix, thus providing maximal aggregation at the border gateways. For
   example, the single 64-bit IPv6 prefix:

       3FFE:1a05:510:2412::/64

   could include literally millions of nodes with ISATAP addresses.



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   This feature would allow a "sparse mode" IPv6 deployment such as the
   deployment of sparse populations of IPv6 hosts on large numbers of
   independent links throughout a large corporate Intranet.

   A final important advantage is that this method supports both sites
   that use globally unique IPv4 address assignments and those that use
   non-globally unique IPv4 addresses, such as when private address
   assignments and/or Network Address Translation are used. By way of
   analogy to the US Postal system, inter-domain transition approaches
   such as [6TO4] provide means for routing messages "cross-country" to
   the "street address" of a distant site while the approach outlined in
   this document provides localized routing information to reach a
   specific (mailstop, apartment number, post office box, etc) WITHIN
   that site.  Thus, the site-level routing information need not have
   relevance outside the scope of that site.


5.  ISATAP Deployment Considerations

   ISATAP addresses should only be used by nodes which do not share a
   common datalink with a native IPv6 router. At least one ISATAP router
   must be configured within the site which advertises an
   administratively- assigned ISATAP prefix in response to an Rtsol mes-
   sage from an off-link host. Such off-link hosts will configure an
   ISATAP pseudo-interface and assign it an address using the ISATAP
   prefix it receives in an Rtadv message solicited from an ISATAP
   router.

   Following ISATAP address configuration, ISATAP hosts automatically
   and transparently communicate the IPv4 address of their *own* end of
   the ISATAP tunnel to any ISATAP host or router which uses the same
   ISATAP prefix.  While nodes may optionally use stateful configuration
   to set an ISATAP prefix and a "default" route that points to an ISA-
   TAP router, a greatly preferred alternative is to provide for
   automatic intra-site IPv6 router discovery and stateless address
   autoconfiguration [DISCUSS].  The following section presents a means
   for the automatic discovery of ISATAP routers.


5.1.  Automatic Discovery of ISATAP Routers

   As described in [AUTO], a node that does not share a common multiple
   access datalink with an IPv6 router will NOT receive unsolicited
   Router Advertisements (Rtadv's), nor will Router Solicitations
   (Rtsol's) from that node reach an IPv6 router on the local link. But,
   the node may still be able to connect to the global IPv6 Internet if
   an ISATAP router for the site exists. Hence, a means for ISATAP
   router discovery is required.  We present the following procedure for



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   a node to initiate ISATAP router discovery (and for an ISATAP router
   to respond) when an on-link IPv6 router is not available:

     - The node constructs an ISATAP link local address for itself
       (as described in section 4.) as:

         FE80::0:5EFE:V4ADDR_NODE

     - The node discovers the IPv4 address for an ISATAP router
       as: V4ADDR_RTR (**)

     - The node sends an Rtsol to the IPv6 "all-routers-multicast" address
       tunneled through the IPv4 infrastructure to the ISATAP router's
       IPv4 address. The addresses used in the IPv6 and IPv4 headers are:

         ipv6_src:  FE80::0:5EFE:V4ADDR_NODE
         ipv6_dst:  FF02::2
         ipv4_src:  V4ADDR_NODE
         ipv4_dst:  V4ADDR_RTR

     - Upon receiving the tunneled Rtsol, the ISATAP router sends
       a unicast Rtadv to the unicast address of the node which sent the
       Rtsol; again, by tunneling the Rtadv through IPv4. The addresses
       used in the IPv6 and IPv4 headers are:

         ipv6_src:  FE80::0:5EFE:V4ADDR_RTR
         ipv6_dst:  FE80::0:5EFE:V4ADDR_NODE
         ipv4_src:  V4ADDR_RTR
         ipv4_dst:  V4ADDR_NODE


     - Upon receiving the Rtsol, the originating node performs address
       autoconfiguration as described in [AUTO] and constructs:

       - a fully-qualified ISATAP address for use as the source address
         for an ISATAP pseudo-interface

       - a default route that points to the ISATAP router

   Note (**) that the above procedure assumes a means for discovering
   V4ADDR_RTR. We present two alternative methods for the automatic
   discovery of V4ADDR_RTR:


5.2.  DNS Well-Known Service Name

   The first method for discovering V4ADDR_RTR employs a new DNS Well-
   Known Service (WKS) name [DNS1,DNS2]. With the establishment of a new



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   well-known service name (e.g. "ISATAPGW"), administrators could pub-
   lish the IPv4 address of a gateway which implementations could use to
   discover V4ADDR_RTR. This method has the advantage that it can be
   deployed immediately using existing mechanisms. However, it requires
   name service lookups and may not always provide the optimum
   V4ADDR_RTR resolution for isolated hosts if multiple ISATAP routers
   are available.


5.3.  IPv4 Anycast for ISATAP routers

   [6TO4ANY] proposes an IPv4 anycast prefix for 6to4 relay routers.
   The proposal suggests an IPv4 prefix assignment 'x.x.x.0/nn' ('nn' is
   currently proposed as 16) where the single address 'x.x.x.1' is
   assigned as the "6to4 IPv6 relay anycast address". We propose analo-
   gous assignments for the purpose of an "ISATAP router anycast
   address". (Whether the reservation of a second /32 assignment from
   the 6to4 IPv4 anycast prefix proposed in [6TO4ANY] would be possible,
   or a separate prefix assignment would be required is a matter of
   debate and TBD.)

   ISATAP routers would advertise the ISATAP router anycast prefix via
   the intra-domain IPv4 routing infrastructure. Isolated IPv6 nodes
   would then use the ISATAP router anycast address as the V4ADDR_RTR
   IPv4 destination for off-link Rtsol's. This approach has the signifi-
   cant advantages that:

     - implementations could hard-code the well-known ISATAP
       anycast address, thus avoiding service discovery via DNS

     - an optimum path to an ISATAP router would be ensured
       by intra-domain IPv4 routing

   As described above, the IPv4 anycast method for locating ISATAP
   routers provides significant functional advantages over the DNS
   approach, while the DNS approach can be implemented immediately pend-
   ing the registration of a WKS name with IANA. While either method
   will work, the decision of which to push for standardization is TBD
   pending discussion at upcoming NGTRANS WG meetings.


6.  Sending Rules and Routing Considerations

   Since each node will be assigned an ISATAP prefix which is adminis-
   tratively reserved for use ONLY by ISATAP nodes, no special sending
   rules are needed.  In particular, correspondent nodes that share a
   common ISATAP prefix will always exchange messages using their ISATAP
   pseudo-interfaces, whereas nodes that do not share a common ISATAP



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   prefix will always exchange messages via standard IPv6 routing. When
   sending a message on an ISATAP pseudo-interface, an implementation
   SHOULD verify that the IPv6 destination address employs the ISATAP
   address construction rules described in section 4 in order to detect
   mis-configured addresses. No other sending rules are necessary.


7.  Address Selection

   No special address selection rules are necessary.


8.  Automatic Deprecation

   ISATAP addresses are intended for use only by nodes which do not
   receive native IPv6 Rtadv's due to not sharing a common datalink with
   an IPv6 router. When native IPv6 Rtadv's become available (such as
   when an IPv6 router is deployed on a node's datalink), the node
   should construct a non-ISATAP aggregatable global IPv6 unicast
   address using address auto-configuration [AUTO] for a non-ISATAP IPv6
   prefix discovered through normal means [DISC].  After the node's
   native IPv6 address is populated in the DNS, the node should eventu-
   ally cease sending Rtsol's to the ISATAP router and discontinue use
   of its ISATAP pseudo-interface.  In this way, ISATAP addresses will
   gradually (and automatically) disappear as IPv6 routers are widely
   deployed within sites.


9.  Multicast Considerations

   Other works in progress [6TO4MULTI] are currently investigating mul-
   ticast addressing issues for [6TO4]. The address format discussed in
   this document is expected to be compatible with those emerging
   approaches.


10.  IANA considerations

   In order to support the EUI-64 address form described in this docu-
   ment, we propose that IANA adopt the EUI-64 Interface Identifier for-
   mat specified in section 4.2 for the existing 00-00-5E OUI owned by
   IANA. No other actions are required by the IANA.


11.  Security considerations

   The ISATAP address format does not support privacy extensions for
   stateless address autoconfiguration [PRIVACY].  However, such privacy



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   extensions are intended primarily to avoid revealing one's MAC
   address, and the ISATAP address format described in this document
   accomplishes this same goal.

   Additional security issues are called out in [6TO4] and probably
   apply here as well.


12.  Implementation status

   The author has implemented the mechanisms described in this draft
   through modifications to the FreeBSD 3.2-RELEASE [FBSD] operating
   system with the INRIA [INRIA] IPv6 distribution. A Linux implementa-
   tion is planned for the June, 2001 timeframe.

   Additionally, Windows XP RC1 will implement elements of the mechanism
   proposed in this paper.

Acknowledgements

   The original ideas presented in this draft were derived from SRI con-
   tractual work. The author recognizes that ideas similar to those in
   this document may have already been presented by others and wishes to
   acknowledge any other such authors. The author also wishes to ack-
   nowledge the government contract administrators who sponsored the
   projects from which these works derived as well as his SRI colleagues
   with whom he has discussed and reviewed this work, including Monica
   Farah-Stapleton, Dr. Mike Frankel, J. Peter Marcotullio, Lou Rodri-
   guez, and Dr. Ambatipudi Sastry.

   The author acknowledges valuable input from numerous members of the
   NGTRANS community which has helped guide the direction of the draft.
   The list of contributors is too long to enumerate, but the input from
   the community has been vital to the draft's evolution. Alain Durand
   deserves special mention for contributing the title of this draft and
   the ISATAP acronym.

   The author finally wishes to provide special acknowledgement to Dave
   Thaler, Art Shelest, Richard Draves, and others at Microsoft Research
   for their ideas on automatic discovery of off-link IPv6 routers. Much
   of the text in section on deployment considerations derives directly
   from discussions with Dave, Art, Rich and others.

References

   [AGGR]     Hinden., R, O'Dell, M., and Deering, S., "An IPv6
              Aggregatable Global Unicast Address Format",
              RFC 2374, July 1998.



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   [ADDR]     Hinden, R., and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 2373, July 1998.

   [AUTO]     Thomson, S., and T. Narten, "IPv6 Stateless Address
              Autoconfiguration", RFC 2462, December 1998.

   [DISC]     Narten, T., Nordmark, E., and W. Simpson, "Neighbor
              Discovery for IP Version 6 (IPv6)", RFC 2461,
              December 1998.

   [DNS1]     Mockapetris, P. "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [DNS2]     Mockapetris, P. "Domain names - Implementation and Specif-
   ication",
              STD 13, RFC 1035, November 1987.

   [DNSSRV]   Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              February 2000.

   [EUI64]    IEEE, "Guidelines for 64-bit Global Identifier (EUI-64)
              Registration Authority",
              http://standards.ieee.org/regauth/oui/tutorials/EUI64.html,
              March 1997

   [IANA]     Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,
              USC/Information Sciences Institute, October 1994.

   [IPV4]     Postel, J., "Internet Protocol", RFC 791

   [IPV6]     Deering, S., and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460

   [6TO4]     Carpenter, B., and K. Moore, "Connection of IPv6 Domains
              via IPv4 Clouds", RFC 3056, February 2001.

   [6TO4ANY]  Huitema, C., "An anycast prefix for 6to4 relay routers",
              draft-ietf-ngtrans-6to4anycsat-02.txt (work in progress)

   [6TO4MULTI] Thaler, D., "Support for Multicsat over 6to4 Networks",
              draft-ietf-ngtrans-6to4-multicast-00.txt (work in pro-
   gress)

   [MECH]     Gilligan, R., and E. Nordmark, "Transition Mechanisms for
              IPv6 Hosts and Routers", RFC 2893, August 2000.

   [SELECT]   Draves, R., Default Address Selection for IPv6, draft-



Templin                       Expires 17 November 2001         [Page 13]

INTERNET-DRAFT   Intra-Site Automatic Tunnel Addressing      17 May 2001


   ietf-
              ipngwg-default-addr-select-00.txt (work in progress)

   [FBSD]     http://www.freebsd.org

   [INRIA]    ftp://ftp.inria.fr/network/ipv6/

   [6BONE]    Rockell, R., and R. Fink, RFC 2772, February 2000.

   [PRIVATE]  Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
   J.,
              and E. Lear, "Address Allocation for Private Internets",
              RFC 1918, February 1996.

   [PRIVACY]  Narten, T., R. Draves, "Privacy Extensions for Stateless
   Address
              Autoconfiguration in IPv6", RFC 3041, January 2001.

   [NAT]      Egevang, K., and P. Francis, "The IP Network Address
              Translator (NAT)", RFC 1631, May 1994.

   [DISCUSS]  private discussions with Dave Thaler, Art Shelest, et al.


Authors Addresses

      Fred L. Templin
      SRI International
      333 Ravenswood Ave.
      Menlo Park, CA 94025, USA

      Email: templin@erg.sri.com

Intellectual Property

   PLACEHOLDER for full IETF IPR Statement if needed.

Full Copyright Statement

   PLACEHOLDER for full ISOC copyright Statement if needed.











Templin                       Expires 17 November 2001         [Page 14]


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