Subject: (ngtrans) ipv6 on the ietf network

From: Marc Blanchet <[email-masked]>
Date: Fri, 09 Mar 2001 13:27:56 -0500

Hi,
	Itojun and us have been providing IPv6 connectivity since Chicago IETF to 
the ietf network during ietf events.  But, this was always aside, having no 
or very minimal support from the host. This situation was acceptable two 
years ago. I don't think it is still acceptable.
	If you believe in IPv6 and are using it daily as many of us do, we need 
REAL commitment from the IETF organisation: IPv6 connectivity on the ietf 
network should be on the same support level and same commitment from the 
host and secretariat.
	And, if, for the ietf own use (ietf events network), ipv6 is second class 
compared to IPv4, how could we clearly convince outsiders about the 
benefits of IPv6?
	This message is asking for support from you, specially the ones that have 
direct seats on the iesg/iab or have influence on the ietf organisation to 
get IPv6 being not an "accident" on the ietf network, but a standard, 
supported, announced at the same time, at the same level as IPv4.

Sorry, this is not a technical mail.

Marc, who is still happy to help and provide IPv6 connectivity, but is 
looking for commitment from the organisation that designed IPv6...

PS. please understand that this message is not targetted to any individual 
or any specific event. It is a general comment.

Marc Blanchet
Viagénie inc.
tel: 418-656-9254
http://www.viagenie.qc.ca

----------------------------------------------------------
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---

From: [email-masked]
Date: Sat, 10 Mar 2001 01:28:26 +0100 (CET)

> network should be on the same support level and same commitment from the

I think wireless LAN is more or less standard at IETFs now because there
is a strong demand for it and many people use it.

So lets all use IPv6 at the next IETF as much as possible and show there
is a large demand and many people use it. I guess Itojun will provide
usage numbers again. I hope those numbers show an increasing amount of
IPv6 users at IETFs during the last few years.

Maybe the 802.11b network in the ngtrans and ipng rooms should be
IPv6 only :-)

BTW, the last few years the RIPE staff have provided IPv6 connectivity
at the RIPE meetings.

	rvdp

---

From: [email-masked]
Date: Sat, 10 Mar 2001 09:36:23 +0900

>IPv6 users at IETFs during the last few years.

	There are situations where IPv6 becomes mandatory at conferences -
	DHCP address pool shortage.  Because there are a lot of 802.11 users,
	and the number of laptop/802.11 users increase, it is getting harder
	to estimate # of users on wireless segment (with wired ethernet we
	could set an upper limit by # of wires).

	At USENIX annual few years ago, DHCP lease time was set to too large
	value, and DHCP address pool went totally sold out.  I was doing
	just fine because I used IPv6 :-)

>Maybe the 802.11b network in the ngtrans and ipng rooms should be

	we should be IPv6-only at Tokyo IETF meeting, year 2002 :-)

>BTW, the last few years the RIPE staff have provided IPv6 connectivity

	great!  maybe we need to supply easy-to-setup configuration for
	terminal room team.  I'll be very happy to help.

itojun

---

From: Randy Bush <[email-masked]>
Date: Fri, 09 Mar 2001 16:47:40 -0800

back in '95 or so, the dhcp server for a few ietfs was my laptop, which i
left plugged in for the whole meeting.  eventually the ACTUAL USE of dhcp
became sufficiently large that it became obvious thit this was a useful
service and worth the extra pain.  and so it became normal for the host
to provide it.

i presume that ACTUALY USE will eventually cause ipv6 to be standard fare
at the meetings.  i suspect that what we have here is a micro-example of
our problem in the general market, the benefits of ipv6 are not perceived
as sufficiently compelling.  we need to change that, not by demanding,
but by making the benefits significantly better and better perceived.

randy

---

From: [email-masked]
Date: Sat, 10 Mar 2001 10:03:57 +0900

(I'm not sure if this is the best place to ask)

	what kind of statistics are useful for us, for IETF50 terminal room
	IPv6 network?  I'm thinking of doing the following by mrtg or whatever:
	- IPv6 inbound/outbound bandwidth for interface
	- estimated # of clients (# of replies to ping6 ff02::1)
	- # of sessions that went through translator

	if you have other ideas, please let me know.

itojun

---

From: "Fred L. Templin" <[email-masked]>
Date: Mon, 12 Mar 2001 16:57:48 -0800

Hello,

Per Bob Fink's instructions, I am posting a new version of:

  draft-templin-ngtrans-v6v4compat-02.txt

for the group's consideration. Please note that this version
is not yet in the draft repository, but will be presented during
the Monday session at IETF 50. Major changes since the previous
version are:

 - 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.

Comments may be sent to this distribution or to:

Fred Templin
[email-masked]

INTERNET-DRAFT                                           Fred L. Templin
                                                       SRI International
                                                       12 March 2001

                Connecting IPv6 Nodes within IPv4 Sites

                            Copyright Notice

                    Placeholder for ISOC copyright.

                draft-templin-ngtrans-v6v4compat-02.txt

Abstract

   This document specifies a method for connecting IPv6 hosts and
   routers (nodes) within predominantly IPv4-based sites. This method is
   based on an IPv6-IPv4 compatibility aggregatable global unicast
   address format (described herein) that embeds the IPv4 address of a
   node within the EUI-64 format interface identifier of an IPv6
   address. 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 multiple access datalink with an IPv6 gateway
   within 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. Moreover, 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.

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   Internet-Drafts are working documents of the Internet Engineering
   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.  _I_n_t_r_o_d_u_c_t_i_o_n

   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 consist of 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 intra-site deployment
   of IPv6 nodes within predominantly IPv4-based intranets.

   The approach outlined in this document is based on a new 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]. The 64-bit address prefix used by
   this format is fully compatible with all existing and emerging prefix
   assignment and inter-domain routing practices (e.g. [6to4],[6BONE]).
   But, the interface identifier employs a special construction using
   the IEEE Organizationally Unique Identifier (OUI) reserved by the
   Internet Assigned Numbers Authority [IANA] along with a "type" field
   to indicate that the identifier encapsulates an IPv4 address suitable
   for automatic intra-domain IPv6-in-IPv4 tunneling.  As such, the
   embedded IPv4 address NEED NOT be globally unique; rather, it need
   only be topologically correct for (and unique within) the context of
   that site.

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

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   multiple access datalink with an IPv6 gateway to join the global IPv6
   network by automatically tunneling IPv6 messages through the IPv4
   routing infrastructure within the site. Two methods for automatic
   discovery of an off-link IPv6 gateway within the site are provided.
   This approach allows large-scale intra-site deployment without incur-
   ring 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; even when multiple levels
   of NAT occur within a given site.

   In the following sections, we present our proposed IPv6-IPv4 compati-
   bility address format in detail. We further discuss technical con-
   siderations for the application of IPv6-IPv4 compatibility addresses
   to facilitate incremental deployment of IPv6 within predominantly
   IPv4-based Intranets.

_2.  _C_h_a_n_g_e_s

   Major changes from version -01 to version 02:

     - 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.  _I_P_v_6-_I_P_v_4 _C_o_m_p_a_t_i_b_i_l_i_t_y _A_d_d_r_e_s_s _F_o_r_m_a_t

   In sections 3.1 and 3.2, 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 necessary to support
   our IPv6-IPv4 compatibility address format, they also provide a flex-
   ible framework for future IANA use. Therefore, we believe the exten-
   sions proposed in sections 3.1 and 3.2 may provide beneficial future
   use to the IANA beyond the scope of IPv6-IPv4 compatibility
   addresses. We present our IPv6-IPv4 compatibility address format pro-
   posal in sections 3.3 and 3.4 and conclude this section with some
   notes on deployment considerations.

   _3._1.  _I_E_E_E _E_U_I-_6_4 _I_n_t_e_r_f_a_c_e _I_d_e_n_t_i_f_i_e_r_s _i_n _I_P_v_6 _A_d_d_r_e_s_s_e_s

   IPv6 aggregatable global and local-use unicast addresses [ADDR]
   include a 64-bit interface identifier in IEEE EUI-64 format [EUI64],

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   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 organi-
   zation owning that OUI.  IEEE EUI-64 interface identifiers are for-
   matted as follows:

    |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,
   as this value is reserved by the IEEE/RAC. However, all other 40-bit
   extension identifier values are available for assignment by the
   addressing authority responsible for a given OUI.

   _3._2.  _A_n _E_U_I-_6_4 _I_n_t_e_r_f_a_c_e _I_d_e_n_t_i_f_i_e_r _F_o_r_m_a_t _f_o_r _I_A_N_A

   The IANA owns IEEE OUI: 0x00005E (also written as: 00-00-5E), and
   [IANA] specifies EUI-48 format (24-bit) interface identifier assign-
   ments 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:

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    |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)

   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 identif-
   ier
                   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.

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   This special TYPE forms the basis for our IPv6-IPv4 compatibility
   aggregatable global unicast address format proposal as described in
   the following sections.

   _3._3.  _I_P_v_6-_I_P_v_4 _C_o_m_p_a_t_i_b_i_l_i_t_y _A_d_d_r_e_s_s _C_o_n_s_t_r_u_c_t_i_o_n

   Using the proposed IANA-specific method for interface identifier con-
   struction discussed in sections 3.1 and 3.2 (with TYPE=0xFE), and
   with reference to [ADDR], we can construct IPv6-IPv4 compatibility
   aggregatable global unicast addresses. Using this methodology, we
   propose an IPv6 address format with embedded IPv4 address in the
   EUI-64 interface identifier. The following diagram shows the con-
   struction:

    | 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    | 02| 00| 5E| FE|   of Endpoint  |
    +--+-----+---+--------+--------+--------------------------------+

   (NOTE: the least significant octet of the OUI in the interface iden-
   tifier is 0x02 instead of 0x00 since u=1 for global 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 IPv6-IPv4 compatibility aggregatable global
   unicast address for this node as:

      3FFE:1a05:510:200:0200:5EFE:8CAD:8108

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

      3FFE:1a05:510:200:0200:5EFE:140.173.129.8

   Similarly, we can construct the link-local and site-local variants
   (respectively) of the IPv6-IPv4 compatibility address as:

      FE80::0200:5EFE:140.173.129.8
      FEC0::200:0200:5EFE:140.173.129.8

   _3._4.  _A_d_v_a_n_t_a_g_e_s

   By embedding an IPv4 address in the interface identifier portion of
   an IPv6 address as described in section 3.3, we can construct aggre-
   gatable global unicast IPv6 addresses that can either be routed

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   globally via the IPv6 infrastructure or automatically tunneled
   locally across portions of a site's IPv4 infrastructure which have no
   native IPv6 routing support.  Thus the addressing scheme supports
   heterogeneous IPv6/IPv4 infrastructures in transition with incremen-
   tal deployment of IPv6 at the site level.  Additionally, a node with
   such an IPv6-IPv4 compatibility address could act as a gateway for
   nodes with native IPv6 addresses connected to the same link, since it
   could automatically tunnel messages across a site's IPv4 domain to
   reach a border IPv6 gateway for the site on behalf of such native
   IPv6 nodes. An example would be deployment of IPv6 on some subset of
   the hosts attached to a workgroup's Ethernet LAN. In this case, one
   host would receive an IPv6-IPv4 compatibility address and act as a
   gateway for the other hosts which receive 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
   IPv6-IPv4 compatibility addresses could be assigned within a common
   IPv6 routing prefix, 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 IPv6-IPv4 compatibil-
   ity addresses. This feature would allow a "sparse mode" IPv6 deploy-
   ment 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.

_3._5.  _D_e_p_l_o_y_m_e_n_t _C_o_n_s_i_d_e_r_a_t_i_o_n_s

   IPv6-IPv4 compatibility addresses should only be used by nodes which
   do not share a common multiple access datalink with an IPv6 router
   for their site. But, there are numerous cases in which such "iso-
   lated" nodes may occur within an heterogeneous IPv6/IPv4 Intranet.

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   Two such examples are:

     - A researcher wishes to run IPv6 on his existing IPv4-based works-
     tation. One or more IPv6 routers are configured within the
     researchers site, but the network administrators have not yet con-
     figured an IPv6 router for the LAN that connects the researcher's
     workstation.

     - A network administrator within a large corporate network wishes
     to configure IPv6 on the existing IPv4 subnets under their jurisd-
     iction, but these subnets are separated from the IPv6 border gate-
     way for the corporation by other IPv4 subnets which are not ready
     for IPv6 deployment.

   In both examples, intra-site IPv6-in-IPv4 tunneling can be used to
   span the "gaps" in IPv6 coverage. The IPv6-IPv4 compatibility address
   format described in the previous subsections provides a means for
   isolated nodes to automatically and transparently communicate the
   IPv4 address of their *own* end of the tunnel to an off-link IPv6
   gateway.  While such nodes may optionally use stateful configuration
   to set a "default" route that points to the off-link gateway, a
   greatly preferred alternative is to provide for automatic intra-site
   IPv6 router discovery and stateless address autoconfiguration [DIS-
   CUSS]. The following section presents a means for the automatic
   discovery of off-link IPv6 routers.

_4.  _A_u_t_o_m_a_t_i_c _D_i_s_c_o_v_e_r_y _o_f _O_f_f-_l_i_n_k _I_P_v_6 _R_o_u_t_e_r_s

   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.
   Hence, a means for off-link IPv6 router discovery is required. We
   present the following procedure for a node to initiate off-link IPv6
   router discovery (and for an off-link IPv6 router to respond) when
   IPv6-IPv4 compatibility addresses are used:

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     - The node constructs an IPv6-IPv4 compatibility link local address
       for itself (as described in section 3.) as:

         FE80::0200:5EFE:V4ADDR_NODE

     - The node discovers the IPv4 address for an off-link IPv6 router
       as: V4ADDR_RTR (**)

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

         ipv6_src:  FE80::0200:5EFE:V4ADDR_NODE
         ipv6_dst:  FF02::2
         ipv4_src:  V4ADDR_NODE
         ipv4_dst:  V4ADDR_RTR

     - Upon receiving the tunneled Rtsol, the off-link IPv6 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::0200:5EFE:V4ADDR_RTR
         ipv6_dst:  FE80::0200:5EFE: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 IPv6-IPv4 compatibility address for use as
         the source address for IPv6 packets

       - a default route that points to the off-link IPv6 router's
         IPv6-IPv4 compatibility link-local address

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

_4._1.  _D_N_S _W_e_l_l-_K_n_o_w_n _S_e_r_v_i_c_e _N_a_m_e

   The first method for discovering V4ADDR_RTR employs a new DNS Well-
   Known Service (WKS) name [DNS1,DNS2]. With the establishment of a new
   well-known service name (e.g. "V6V4GW"), administrators could publish
   the IPv4 address of a gateway which implementations could use to

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   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 which use IPv6-IPv4 compati-
   bility addresses.

_4._2.  _I_P_v_4 _A_n_y_c_a_s_t _f_o_r _I_n_t_r_a-_d_o_m_a_i_n _I_P_v_6 _r_o_u_t_e_r

   [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 "IPv6-IPv4 compatibility
   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 '/16' would be required is a matter
   of debate and TBD.)

   Any IPv6 router capable of providing an IPv6-IPv4 compatibility
   address-based tunnel endpoint as described in the previous sections
   would advertise the IPv6-IPv4 compatibility router anycast prefix via
   the intra-domain IPv4 routing infrastructure. Isolated IPv6 nodes
   would then use the IPv6-IPv4 compatibility router anycast address as
   the V4ADDR_RTR IPv4 destination for off-link Rtsol's. This approach
   has the significant advantages that:

     - implementations could hard-code the well-known V6V4Compat
       anycast address, thus avoiding service discovery via DNS

     - an optimum path to an off-link IPv6 router would be ensured
       by intra-domain IPv4 routing

   As described above, the IPv4 anycast method for locating intra-domain
   routers that support IPv6-IPv4 compatibility address-based tunneling
   provides significant functional advantages over the DNS approach,
   while the DNS approach can be implemented immediately pending the
   registration of a WKS name with IANA. While either method will work,
   the decision of which to push for standardization is TBD pending dis-
   cussion at upcoming NGTRANS WG meetings.

_5.  _S_e_n_d_i_n_g _R_u_l_e_s _a_n_d _R_o_u_t_i_n_g _C_o_n_s_i_d_e_r_a_t_i_o_n_s

   The sending rule for a host or router that sends an IPv6 packet to an
   IPv6-IPv4 compatibility destination address is simple and direct:

     "If the 64-bit IPv6 prefix of the IPv6-IPv4 compatibility

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     destination address matches the 64-bit IPv6 prefix of one of my
     network interfaces, tunnel the packet through IPv4 - else, route
     the packet through IPv6."

   From the above rule, a sender that does NOT have an interface which
   shares a common 64-bit routing prefix with the packet's IPv6-IPv4
   compatibility destination address simply sends the packet to the
   next-hop gateway determined by an ordinary IPv6 routing table lookup.
   In short, when a sending node does not have an interface which shares
   a common 64-bit (site-level) routing prefix with an IPv6-IPv4 compa-
   tibility destination address, the sending rule is identical to that
   for a native IPv6 destination address. This decision is independent
   of whether the sender has an IPv6-IPv4 compatibility address itself,
   or whether the sender even comprises a dual-stack configuration.
   Indeed, the sender can simply be a native IPv6 node with no legacy
   IPv4 support.

   When a sender has an interface which shares a common 64-bit routing
   prefix with an IPv6-IPv4 compatibility destination address, however,
   the sender must assume that the destination is NOT directly reachable
   at the datalink level - even though the shared site-level routing
   prefix implies otherwise. Instead, if the sender comprises a dual-
   stack configuration, it should automatically tunnel the IPv6 packet
   (via IPv6-in-IPv4 tunneling as described in [MECH]) to the IPv4
   address embedded within the IPv6-IPv4 compatibility destination
   address' interface identifier. If the sender is an IPv6-only node
   that DOES NOT comprise a dual-stack configuration, however, it has no
   means for automatically tunneling the packet via IPv4. In this case:

     - If the sender is the host that originates the packet, it should
       send the packet to a router that lists the 64-bit prefix in its
       router advertisements. If no such router exists, the sender should
       drop the packet and return a "No route to host" error indication
       to the originating application.

     - If the sender is a router that forwards the packet, it should drop
       the packet and send an ICMPv6 "Destination Unreachable" message to
       the source

   By implication, the scheme breaks down if a packet with an IPv6-IPv4
   compatibility destination address reaches an IPv6-only router that
   has an interface which shares a common 64-bit routing prefix with the
   destination address. Additional mechanisms to address this issue
   might be possible, such as allowing dual-stack routers to advertise
   96-bit prefixes which incorporate the special 32-bit EUI-64 interface
   identifier prefix: 0200:5EFE. A sender could then interpret such an
   advertisement to mean that the advertising router comprises a dual
   stack and is capable of intra-site IPv6-in-IPv4 tunneling. But a

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   reasonable argument could be made to the effect that:

     "By the time IPv6-only routers begin to proliferate throughout a
     site, nodes within the site should no longer be using IPv6-IPv4
     compatibility addresses."

   In fact, the advent of IPv6-only routers within a site would serve as
   a strong indication that the site is no longer a predominantly IPv4-
   based infrastructure in transition, but rather that the transition is
   either complete or nearly complete. Therefore, IPv6-IPv4 compatibil-
   ity addresses should no longer be used.

_6.  _A_d_d_r_e_s_s _S_e_l_e_c_t_i_o_n

   Other works in progress ([6TO4] and [SELECT]) have begun to explore
   the subject of address selection when multiple IPv6 destination
   address alternatives are available. These address selection policies
   deal with the 64-bit IPv6 routing prefix and thus can be applied
   independently of whether/not the destination address alternatives are
   constructed as described in this document. However, in order to
   ensure efficient routing within the destination's site, we propose
   the following simple "second-tier" address selection policy for deal-
   ing with IPv6-IPv4 compatibility addresses:

     "If multiple alternatives remain after address selection has been
     applied on the 64-bit routing prefixes, and if at least one of the
     remaining alternatives is constructed with a native IPv6 interface
     identifier (one that does NOT contain an embedded IPv4 address as
     described in this document), select a native IPv6 address.  Other-
     wise, select an IPv6-IPv4 compatible address."

   This policy decision is in keeping with the concept that NGTRANS
   transition mechanisms should remain in place ONLY as long as needed
   and should be disabled as soon as native IPv6 mechanisms become
   available.

_7.  _A_u_t_o_m_a_t_i_c _D_e_p_r_e_c_a_t_i_o_n

   IPv6-IPv4 compatibility addresses constructed in the manner described
   in this document are intended for use only by nodes which do not
   receive router advertisements due to not sharing a common multiple
   access datalink with an IPv6 router. When router advertisements
   become available (such as when an IPv6 router is deployed on a common
   multiple access datalink shared by the node), the node should discon-
   tinue use of its IPv6-IPv4 compatibility address and adopt a normal
   aggregatable global IPv4 unicast address using address auto-

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   configuration [AUTO] for a prefix discovered through normal router
   discovery [DISC] means. In this way, IPv6-IPv4 compatibility
   addresses will gradually (and automatically) disappear as IPv6
   routers become widely deployed within a site.

_8.  _M_u_l_t_i_c_a_s_t _C_o_n_s_i_d_e_r_a_t_i_o_n_s

   Other works in progress are currently investigating IPv4-mapped mul-
   ticast addressing issues. The address format discussed in this docu-
   ment is expected to be compatible with those emerging approaches.

_9.  _R_e_l_a_t_i_o_n _t_o _o_t_h_e_r _w_o_r_k_s _i_n _p_r_o_g_r_e_s_s

   The IPv6-IPv4 compatibility address format and routing policy deci-
   sions presented in this draft evolved from SRI contractual works out-
   side the scope of the NGTRANS working group. Additionally, the
   mechanisms presented in this draft were developed by the author with
   no prior knowledge of the activities in NGTRANS. The author recog-
   nizes that other works in progress seek to address very similar
   IPv4-IPv6 transition issues as those targeted by this draft. However,
   the approach described in this draft presents a number of unique
   advantages for NGTRANS that supplement the other works in progress.
   (Most specifically, advantages for incremental deployment of IPv6
   nodes at the intra-domain level.)

_1_0.  _I_A_N_A _c_o_n_s_i_d_e_r_a_t_i_o_n_s

   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 3.2 for the existing 00-00-5E OUI owned by
   IANA. No other actions are required by the IANA.

_1_1.  _S_e_c_u_r_i_t_y _c_o_n_s_i_d_e_r_a_t_i_o_n_s

   The IPv6-IPv4 compatibility address format does not support privacy
   extensions for stateless address autoconfiguration [PRIVACY].  How-
   ever, such privacy extensions are intended primarily to avoid reveal-
   ing one's MAC address, and the IPv6-IPv4 compatibility address format
   described in this document accomplishes this same goal.

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

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_1_2.  _I_m_p_l_e_m_e_n_t_a_t_i_o_n _s_t_a_t_u_s

   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. These modifications
   implement the sending rules and routing considerations as described
   in section 5. The source code is not yet ready for public distribu-
   tion, but the author would be happy to discuss details with
   interested parties.

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

Acknowledgements

   The ideas presented in this draft were derived from SRI contractual
   work.  The author recognizes that ideas similar to those in this
   document may have already been presented by others and wishes to ack-
   nowledge 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 Dr. Mike
   Frankel, J. Peter Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sas-
   try.

   The author acknowledges discussions with Alain Durand and Keith Moore
   during the IETF 48 conference in Pittsburgh, PA. which helped
   motivate ideas on restructuring this document from the first version.

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

References

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

   [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

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              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)

   [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-
   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.,

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              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: [email-masked]

Intellectual Property

   PLACEHOLDER for full IETF IPR Statement if needed.

Full Copyright Statement

   PLACEHOLDER for full ISOC copyright Statement if needed.

Templin                        Expires 12 October 2001         [Page 16]

---

From: [email-masked]
Date: Mon, 19 Mar 2001 01:45:15 +0900

>	- # of sessions that went through translator

	just as a starter:
	http://www.kame.net/ietf50/numhosts.png
	updated manually a couple of times a day.

	all stats will be liked from http://www.kame.net/ietf50/.

itojun

---

From: Randy Bush <[email-masked]>
Date: Sun, 18 Mar 2001 09:10:30 -0800

> 	http://www.kame.net/ietf50/numhosts.png

an inaccuracyof this graph is that it shows how many people have v6-enabled
kernels, which is larger (by at least this laptop) than those using v6 as
the transport.  though i hope to get mine running transport this afternoon.

randy

---

From: Jun-ichiro itojun Hagino <[email-masked]>
Date: Mon, 19 Mar 2001 02:13:58 +0900

>the transport.  though i hope to get mine running transport this afternoon.

	correct.  for example, at this moment, on wireless segment,
	- from ping6 ff02::1, i see 13 IPv6-enabled kernels that can respond.
	- from NDP table, i see at least 7 nodes with IPv6 global address
	  configured (supposedly they are configured to use IPv6).

	maybe i should try to draw the graph for the latter one.

itojun

---

From: Randy Bush <[email-masked]>
Date: Sun, 18 Mar 2001 09:24:21 -0800

> 	maybe i should try to draw the graph for the latter one.

spend a second color, do both!  :-)

randy

---

From: Jun-ichiro itojun Hagino <[email-masked]>
Date: Tue, 20 Mar 2001 10:06:46 +0900

>spend a second color, do both!  :-)

	due to the presense of STALE entries, and the use of RFC3041 temporary
	addresses, it was not a good idea to count # of nodes on ND
	(it just keep goes up).

	it seems that there are fair number of IPv6-enabled (responds to
	IPv6 ping) nodes.  i wonder how many IPv4 nodes are there...
	(is it possible to get # of DHCPv4 leases?  i don't want to do
	broadcast ping...)

itojun