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Versions: 00

IPv6 maintenance Working Group(6man)                             Lin Luo
Internet-Draft                                           H3C Corporation
Intended status: Standards Track                            Qianli Zhang
Expires: December 30, 2019                           Tsinghua University
                                                           HaiHong Zhang
                                                         H3C Corporation
                                                           June 30, 2019


           Enhanced IPv6 Stateless Address autoconfiguration
                 draft-luo-6man-ipv6-ra-prefix-flag-00

Abstract

   This document specifies new flag in the format of a Prefix
   Information Option, IPv6 routers advertise the address refresh
   capability and address generation mechanism to IPv6 hosts.

Status of This Memo

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

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   This Internet-Draft will expire on November 20, 2019.

Copyright Notice

   Copyright (c) 2019 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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specification of Requirements . . . . . . . . . . . . . . . .   2
   3.  Algorithm Specification . . . . . . . . . . . . . . . . . . .   3
     3.1.  Prefix Information Option . . . . . . . . . . . . . . . .   3
     3.2.  Router processing  . . . . . . . . . . . . . . . . . . .    4
     3.3.  Host processing  . . . . . . . . . . . . . . . . . . . .    5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Normative References  . . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7







































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1.  Introduction

   The IPv6 Neighbor Discovery (ND) Protocol [RFC4861] specifies router
   advertisement message contains Prefix Information Option, [RFC4862]
   specifies Stateless Address Autoconfiguration (SLAAC), On the other
   hand, Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC8415]
   is used when a site requires tighter control over exact address
   assignments.

   IPv6 hosts generate addresses composed of prefix advertised by
   router, an Interface Identifier(IID) in [RFC4291] typically embeds
   the link-layer address. In [RFC4941], the concept of a temporary
   address is proposed for privacy concerns, the host randomly generates
   a temporary identification and the temporary address is regenerated
   on a periodic basis. [RFC6724] recommends the host needs to prefer
   the temporary address above the public address. Various new forms of
   IIDs have been defined, including Cryptographically Generated
   Addresses (CGAs) [RFC4982] of Secure Neighbor Discovery (SEND)
   [RFC3971] and others.

   The security and privacy implications of different IPv6 IIDs are
   discussed, and [RFC8064] recommends semantically opaque address as
   the default scheme for generating IPv6 stable addresses with SLAAC.
   Otherwise, the mechanism of temporary address generation and address
   selection are widely used by most operating systems.

   This document specifies a new flag in the format of a Prefix
   Information Option, IPv6 routers advertise the address refresh
   capability and address generation mechanism to IPv6 hosts. Despite
   hosts choose any IIDs generation forms, according to address refresh
   capability, it is easy to perform extending lifetime of temporary
   address and public address. [RFC7136] specifies IIDs MUST be viewed
   as an opaque bit string by third parties, except in the local
   context, the address generation flag provides a mechanism in
   different kinds of application scenarios, such as authorized network
   and location service network.

2.  Specification of Requirements

   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 [RFC2119].









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3.  Algorithm Specification

   In a local context, when hosts need authentication to access the
   network, most routers offer the capability of flow monitoring and
   quality of service based on host IPv6 address, stable address is
   required here. Instead of letting host freely generate an address, it
   is better to specify that the address time is forced to refresh.
   Furthermore, routers can choose the address generation mechanism to
   advertise, including CGA, stable and semantically opaque address,
   address based on location.

   3.1.  Prefix Information Option
       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     | Prefix Length |L|A|R|T|Mode|Res|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Valid Lifetime                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Preferred Lifetime                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Reserved2                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                            Prefix                             +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      This format represents the following changes over that originally
   specified for Neighbor Discovery [RFC4861] [RFC6275]:

      T              1-bit address time refresh flag. When set,
                     indicates that the address generated by this prefix
                     must be refreshed.

      Mode           3-bit unsigned integer indicating the address
                     generation mode, the follow mode values are
                     currently defined:

                       0    default addresses mode
                       1    [RFC7217] stable,opaque addresses mode
                       2    [RFC3972] CGA mode

      Reserved1      Reduced from a 5-bit field to a 1-bit field to



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                     account for the addition of the above bit.

3.2.  Router Specification

A router sends Router Advertisement messages periodically or in response
to Router Solicitation. Prefix information Option specifies prefix and
corresponding flags which is used for stateless address
autoconfiguration. In each prefix information option:

a) If the router does not specify the address refresh flag and
generation mode , it must be set to 0.

b) If the Autonomous flag is set to 0, the address refresh flag and
generation mode should be set to 0.

c) According to the network configuration, the address refresh flag or
generation mode should be set to an appropriate value.

3.3.  Host Specification

Upon receipt of a valid Router Advertisement message:

a) If the Autonomous flag is set to 0, the address refresh flag and
address generation mode should be silently ignored.

b) If the prefix is link-local prefix, the address refresh flag and
address generation mode should be silently ignored.

c) If the Prefix Information Option is valid to generate address:

      1) The host must expand the time of address when the address
     refresh flag is set to 1.

      2) The generate mode should be ignored if the host does not
     support.

      3) The generation mode flag is set to 0, the address is generated
     by default.

      4) Host should generate address as the mode described.

4.  Security Considerations


   This document specifies a new flag in the format of a Prefix
   Information Option, IPv6 routers to advertise the address refresh
   capability and address generation mechanism to IPv6 hosts. The
   inclusion of additional bit fields provides extend information of



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   network, it shares the security issues of NDP that are documented in
   [RFC4861]. It recommends the existed scheme for generating IPv6
   address with SLAAC, such that the security and privacy issues of IIDs
   are mitigated.















































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5.  IANA Considerations

   This document does not include an IANA request.

6.  Normative References


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

   [RFC3971]  Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
              Neighbor Discovery (SEND)", RFC 3971, March 2005.
              <https://www.rfc-editor.org/info/rfc3971>.

   [RFC3972]  Aura, T., "Cryptographically Generated Addresses
              (CGA)",RFC 3972, March 2005.
              <https://www.rfc-editor.org/info/rfc3972>.

   [RFC4291]  R. Hinden, S. Deering, "IP Version 6 Addressing
              Architecture",RFC4291, DOI 10.17487/RFC4291, February
              2006. <https://www.rfc-editor.org/info/rfc4291>.

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

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, DOI
              10.17487/RFC4862, September 2007.
              <https://www.rfc-editor.org/info/rfc4862>.

   [RFC4941]  T. Narten, R. Draves, S. Krishnan, "Privacy Extensions for
              Stateless Address Autoconfiguration in IPv6",RFC4941, DOI
              10.17487/RFC4941, September 2007.<https://www.rfc-
              editor.org/info/rfc4941>.

   [RFC4982]  M. Bagnulo, J. Arkko, "Support for Multiple Hash
              Algorithms in Cryptographically Generated Addresses
              (CGAs)",RFC4982, DOI 10.17487/RFC4982, July 2007.
              <https://www.rfc-editor.org/info/rfc4982>.


   [RFC6275]  C. Perkins, D. Johnson, and J. Arkko, "Mobility Support in
              IPv6", RFC 6275, DOI 10.17487/RFC6275, July 2011.
              <https://www.rfc-editor.org/info/rfc6275>.




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   [RFC6724]  D. Thaler, R. Draves, and A. Matsumoto, "Default Address
              Selection for Internet Protocol Version 6 (IPv6)",
              RFC6724, DOI 10.17487/RFC6724, September 2012.
              <https://www.rfc-editor.org/info/rfc6724.

   [RFC7136]  B. Carpenter, S. Jiang, "Significance of IPv6 Interface
              Identifiers",RFC7136, DOI 10.17487/RFC7136, February 2014.
              <https://www.rfc-editor.org/info/rfc7136>.

   [RFC7217]  F. Gont, "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)",RFC7217, DOI 10.17487/RFC7217,
              April 2014. <https://www.rfc-editor.org/info/rfc7217>.


   [RFC8064]  F. Gont, A. Cooper, D. Thaler, W. Liu, "Recommendation on
              Stable IPv6 Interface Identifiers",RFC8064, DOI
              10.17487/RFC8064, February 2017. <https://www.rfc-
              editor.org/info/rfc8064>.

   [RFC8415]  T. Mrugalski, M. Siodelski, B. Volz, A. Yourtchenko, M.
              Richardson, S. Jiang, T. Lemon, T. Winters, "Dynamic Host
              Configuration Protocol for IPv6 (DHCPv6)", RFC 8415,
              November 2018. <https://www.rfc-editor.org/info/rfc8415>.



























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Authors' Addresses

   Lin Luo
   H3c Corporation
   Hangzhou,
   P.R.China

   Email: extrall@h3c.com


   Haihong Zhang
   H3c Corporation
   Beijing,
   P.R.China

   Email: zhanghaihong.04355@h3c.com


   Qianli Zhang
   Tsinghua University
   Beijing, 100086
   P.R.China

   EMail: zhang@cernet.edu.cn



























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