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Versions: 00 01 02 draft-ietf-6man-ra-pref64

IPv6 Maintenance                                              L. Colitti
Internet-Draft                                                  E. Kline
Intended status: Standards Track                              J. Linkova
Expires: January 20, 2019                                         Google
                                                           July 19, 2018


              Discovering PREF64 in Router Advertisements
                  draft-pref64folks-6man-ra-pref64-00

Abstract

   This document specifies a Router Advertisement option to configure
   the NAT64 prefix.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on January 20, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Why include the NAT64 prefix in Router Advertisements . . . .   2
   3.  Semantics . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Option format . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   4
     7.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   NAT64 [RFC6146] with DNS64 [RFC6147] is a widely-deployed mechanism
   to provide IPv4 access on IPv6-only networks.  In order to support
   functions such as local validation of DNSSEC [RFC4033] responses,
   464xlat [RFC6877], and local IPv4 address synthesis [RFC8305], the
   host must be aware of the NAT64 prefix in use by the network.  This
   document specifies a Router Advertisement [RFC4861] option to
   communicate the NAT64 prefix to hosts.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Why include the NAT64 prefix in Router Advertisements

   Fate sharing.  NAT64 requires a routing to be configured.  IPv6
   routing configuration requires receiving an IPv6 Router Advertisement
   [RFC4861].  Compared to currently-deployed NAT64 prefix discovery
   methods such as [RFC7050], including the NAT64 prefix in the Router
   Advertisement minimizes the number of packets required to configure a
   host.  This speeds up the process of connecting to a network that
   supports NAT64/DNS64, and simplifies host implementation by removing
   the possibility that the a can have an incomplete layer 3
   configuration (e.g., IPv6 addresses and prefixes, but no NAT64
   prefix).

   Deployability.  All IPv6 hosts and networks are required to support
   [RFC4861].  Other options such as [RFC7225]b require implementing
   other protocols.




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3.  Semantics

   This option specifies exactly one NAT64 prefix for all IPv4
   addresses.  Observation of current deployments suggest that they use
   RFC7050, which also only supports one prefix.

   This option only supports the NAT64 prefix length of 96 bits.  In the
   unlikely event of use cases for shorter prefixes ([RFC6052]) emerging
   another option could be created.

4.  Option format


      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type      |    Length     |           Lifetime            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                            Prefix                             +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                   Figure 1: NAT64 Prefix Option Format

   Fields:

   Type     8-bit identifier of the RDNSS option type as assigned by
            IANA: TBD
   Length   8-bit unsigned integer.  The length of the option (including
            the Type and Length fields) is in units of 8 octets. The
            only valid value for this filed is 2. A host MUST ignore the
            NAT64 prefix option if the length field value is not set to
            2.
   Lifetime 16-bit unsigned integer.  The maximum time in seconds over
            which this NAT64 prefix MAY be used. The value of Lifetime
            SHOULD by default be set to lesser of  3 x MaxRtrAdvInterval
            or 65535 seconds.  A value of zero means that the prefix
            MUST no longer be used.
   Prefix   The highest 96-bits of the NAT64 prefix.

5.  IANA Considerations

   The IANA is requested to assign a new IPv6 Neighbor Discovery Option
   type for the PREF64 option defined in this document.




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                         +---------------+-------+
                         | Option Name   | Type  |
                         +---------------+-------+
                         | PREF64 option | (TBD) |
                         +---------------+-------+

                                  Table 1

   The IANA registry for these options is:

      https://www.iana.org/assignments/icmpv6-parameters [1]

6.  Security Considerations

   Because Router Advertisements are required in all IPv6 configuration
   scenarios, on IPv6-only networks, Router Advertisements must already
   be secured, e.g., by deploying RA guard [RFC6105].  Providing all
   configuration in Router Advertisements increases security by ensuring
   that no other protocols can be abused by malicious attackers to
   provide hosts with invalid configuration.

   The security measures that must already be in place to ensure that
   Router Advertisements are only received from legitimate sources
   eliminate the problem of PREF64 validation described in section 3.1
   of [RFC7050].

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              DOI 10.17487/RFC6052, October 2010,
              <https://www.rfc-editor.org/info/rfc6052>.

7.2.  Informative References

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/info/rfc4033>.





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   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC6105]  Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
              Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
              DOI 10.17487/RFC6105, February 2011,
              <https://www.rfc-editor.org/info/rfc6105>.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
              April 2011, <https://www.rfc-editor.org/info/rfc6146>.

   [RFC6147]  Bagnulo, M., Sullivan, A., Matthews, P., and I. van
              Beijnum, "DNS64: DNS Extensions for Network Address
              Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
              DOI 10.17487/RFC6147, April 2011,
              <https://www.rfc-editor.org/info/rfc6147>.

   [RFC6877]  Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
              Combination of Stateful and Stateless Translation",
              RFC 6877, DOI 10.17487/RFC6877, April 2013,
              <https://www.rfc-editor.org/info/rfc6877>.

   [RFC7050]  Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
              the IPv6 Prefix Used for IPv6 Address Synthesis",
              RFC 7050, DOI 10.17487/RFC7050, November 2013,
              <https://www.rfc-editor.org/info/rfc7050>.

   [RFC7225]  Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the
              Port Control Protocol (PCP)", RFC 7225,
              DOI 10.17487/RFC7225, May 2014,
              <https://www.rfc-editor.org/info/rfc7225>.

   [RFC8305]  Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2:
              Better Connectivity Using Concurrency", RFC 8305,
              DOI 10.17487/RFC8305, December 2017,
              <https://www.rfc-editor.org/info/rfc8305>.

7.3.  URIs

   [1] https://www.iana.org/assignments/icmpv6-parameters







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Authors' Addresses

   Lorenzo Colitti
   Google
   Roppongi 6-10-1
   Minato, Tokyo  106-6126
   JP

   Email: lorenzo@google.com


   Erik Kline
   Google
   Roppongi 6-10-1
   Minato, Tokyo  106-6126
   JP

   Email: ek@google.com


   Jen Linkova
   Google
   1 Darling Island Rd
   Pyrmont, NSW  2009
   AU

   Email: furry@google.com
























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