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DHCPv6 Options for Home Network Naming Authority
draft-ietf-homenet-naming-architecture-dhc-options-22

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9527.
Authors Daniel Migault , Ralf Weber , Tomek Mrugalski
Last updated 2022-10-20 (Latest revision 2022-10-19)
Replaces draft-mglt-homenet-naming-architecture-dhc-options
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Send notices to stephen.farrell@cs.tcd.ie
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draft-ietf-homenet-naming-architecture-dhc-options-22
Homenet                                                       D. Migault
Internet-Draft                                                  Ericsson
Intended status: Standards Track                                R. Weber
Expires: 23 April 2023                                            Akamai
                                                            T. Mrugalski
                                       Internet Systems Consortium, Inc.
                                                         20 October 2022

            DHCPv6 Options for Home Network Naming Authority
         draft-ietf-homenet-naming-architecture-dhc-options-22

Abstract

   This document defines DHCPv6 options so an Homenet Naming Authority
   (HNA) can automatically proceed to the appropriate configuration and
   outsource the authoritative naming service for the home network.  In
   most cases, the outsourcing mechanism is transparent for the end
   user.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on 23 April 2023.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Procedure Overview  . . . . . . . . . . . . . . . . . . . . .   4
   4.  DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Registered Homenet Domain Option  . . . . . . . . . . . .   5
     4.2.  Forward Distribution Manager Option . . . . . . . . . . .   5
     4.3.  Reverse Distribution Manager Server Option  . . . . . . .   6
     4.4.  Supported Transport . . . . . . . . . . . . . . . . . . .   7
   5.  DHCPv6 Behavior . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . .   8
     5.2.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . .   8
     5.3.  DHCPv6 Relay Agent Behavior . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  DHCPv6 Option Codes . . . . . . . . . . . . . . . . . . .   8
     6.2.  Supported Transport parameter . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Appendix A.  Scenarios and impact on the End User . . . . . . . .  11
     A.1.  Base Scenario . . . . . . . . . . . . . . . . . . . . . .  11
     A.2.  Third Party Registered Homenet Domain . . . . . . . . . .  12
     A.3.  Third Party DNS Infrastructure  . . . . . . . . . . . . .  12
     A.4.  Multiple ISPs . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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   The reader should be familiar with
   [I-D.ietf-homenet-front-end-naming-delegation].

2.  Introduction

   [I-D.ietf-homenet-front-end-naming-delegation] specifies how an
   entity designated as the Homenet Naming Authority (HNA) outsources a
   Public Homenet Zone to an DNS Outsourcing Infrastructure (DOI).

   This document describes how a network can provision the HNA with a
   specific DOI.  This could be particularly useful for a DOI partly
   managed by an ISP, or to make home networks resilient to HNA
   replacement.  The ISP delegates an IP prefix to the home network as
   well as the associated reverse zone.  The ISP is thus aware of the
   owner of that IP prefix, and as such becomes a natural candidate for
   hosting the Homenet Reverse Zone - that is the Reverse Distribution
   Manager (RDM) and potentially the Reverse Public Authoritative
   Servers.

   In addition, ISPs often identify the line of the home network with a
   name.  Such name is used for their internal network management
   operations and is not a name the home network owner has registered
   to.  ISPs may leverage such infrastructure and provide the homenet
   with a specific domain name designated as per
   [I-D.ietf-homenet-front-end-naming-delegation] a Homenet Registered
   Domain.  Similarly to the reverse zone, ISPs are aware of who owns
   that domain name and may become a natural candidate for hosting the
   Homenet Zone - that is the Distribution Manager (DM) and the Public
   Authoritative Servers.

   This document describes DHCPv6 options that enable an ISP to provide
   the necessary parameters to the HNA, to proceed.  More specifically,
   the ISP provides the Registered Homenet Domain, necessary information
   on the DM and the RDM so the HNA can manage and upload the Public
   Homenet Zone and the Reverse Public Homenet Zone as described in
   [I-D.ietf-homenet-front-end-naming-delegation].

   The use of DHCPv6 options may make the configuration completely
   transparent to the end user and provides a similar level of trust as
   the one used to provide the IP prefix - when provisioned via DHCP.

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3.  Procedure Overview

   This section illustrates how a HNA receives the necessary information
   via DHCPv6 options to outsource its authoritative naming service to
   the DOI.  For the sake of simplicity, and similarly to
   [I-D.ietf-homenet-front-end-naming-delegation], this section assumes
   that the HNA and the home network DHCPv6 client are colocated on the
   Customer Edge (CPE) router [RFC7368].  Note also that this is not
   mandatory and the DHCPv6 client may instruct remotely the HNA with a
   protocol that will be standardized in the future.  In addition, this
   section assumes the responsible entity for the DHCPv6 server is
   provisioned with the DM and RDM information - associated with the
   requested Registered Homenet Domain . This means a Registered Homenet
   Domain can be associated with the DHCPv6 client.

   This scenario is believed to be the most popular scenario.  This
   document does not ignore scenarios where the DHCPv6 server does not
   have privileged relations with the DM or RDM.  These cases are
   discussed in Appendix A.  Such scenarios do not necessarily require
   configuration for the end user and can also be zero-config.

   The scenario considered in this section is as follows:

   1.  The HNA is willing to outsource the Public Homenet Zone or
       Homenet Reverse Zone.  The DHCPv6 client is configured to include
       in its Option Request Option (ORO) the Registered Homenet Domain
       Option (OPTION_REGISTERED_DOMAIN), the Forward Distribution
       Manager Option (OPTION_FORWARD_DIST_MANAGER) and the Reverse
       Distribution Manager Option (OPTION_REVERSE_DIST_MANAGER) option
       codes.

   2.  The DHCPv6 server responds to the DHCPv6 client with the
       requested DHCPv6 options based on the identified homenet.  The
       DHCPv6 client passes the information to the HNA.

   3.  The HNA is authenticated (see Section "Securing the Control
       Channel" of [I-D.ietf-homenet-front-end-naming-delegation]) by
       the DM and the RDM.  The HNA builds the Homenet Zone (or the
       Homenet Reverse Zone) and proceed as described in
       [I-D.ietf-homenet-front-end-naming-delegation].  The DHCPv6
       options provide the necessary non optional parameters described
       in Appendix B of [I-D.ietf-homenet-front-end-naming-delegation].
       The HNA may complement the configurations with additional
       parameters via means not yet defined.  Appendix B of
       [I-D.ietf-homenet-front-end-naming-delegation] describes such
       parameters that may take some specific non default value.

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4.  DHCPv6 Option

   This section details the payload of the DHCPv6 options following the
   guidelines of [RFC7227].

4.1.  Registered Homenet Domain Option

   The Registered Domain Option (OPTION_REGISTERED_DOMAIN) indicates the
   FQDN associated with the home network.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   OPTION_REGISTERED_DOMAIN    |         option-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   /                   Registered Homenet Domain                   /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: Registered Domain Option

   *  option-code (16 bits): OPTION_REGISTERED_DOMAIN, the option code
      for the Registered Homenet Domain (TBD1).

   *  option-len (16 bits): length in octets of the Registered Homenet
      Domain field as described in [RFC8415].

   *  Registered Homenet Domain (variable): the FQDN registered for the
      homenet encoded as described in Section 10 of [RFC8415].

4.2.  Forward Distribution Manager Option

   The Forward Distributed Manager Option (OPTION_FORWARD_DIST_MANAGER)
   provides the HNA with the FQDN of the DM as well as the transport
   protocols for the communication between the HNA and the DM.  As
   opposed to IP addresses, the FQDN requires a DNS resolution before
   establishing the communication between the HNA and the DM.  However,
   the use of a FQDN provides multiple advantages over IP addresses.
   Firstly, it makes the DHCPv6 Option easier to parse and smaller -
   especially when IPv4 and IPv6 addresses are expected to be provided.
   Then the FQDN can reasonably be seen as a more stable identifier than
   IP addresses, as well as a pointer to additional information that may
   be useful, in the future, to establish the communication between the
   HNA and the DM.

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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  OPTION_FORWARD_DIST_MANAGER  |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Supported Transport       |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   /                  Distribution Manager  FQDN                   /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 2: Forward Distribution Manager Option

   *  option-code (16 bits): OPTION_FORWARD_DIST_MANAGER, the option
      code for the Forward Distribution Manager Option (TBD2).

   *  option-len (16 bits): length in octets of the enclosed data as
      described in [RFC8415].

   *  Supported Transport (16 bits): defines the supported transport by
      the DM (see Section 4.4).  Each bit represents a supported
      transport, and a DM MAY indicate the support of multiple modes.
      The left most bit for DNS over TLS [RFC7858] MUST be set.

   *  Distribution Manager FQDN (variable): the FQDN of the DM encoded
      as described in Section 10 of [RFC8415].

   It is worth noticing that the Supported Transport field does not
   enable to specify a port and the used port is defined by a standard.
   In the case of DNS over TLS [RFC7858], the port is defined by
   [RFC7858] to be 853.  The need for such flexibility has been balanced
   with the difficulty of handling a list of tuples ( transport, port )
   as well as the possibility to use a dedicated IP address for the DM.

4.3.  Reverse Distribution Manager Server Option

   The Reverse Distribution Manager Option (OPTION_REVERSE_DIST_MANAGER)
   provides the HNA with the FQDN of the DM as well as the transport
   protocols for the communication between the HNA and the DM.

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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | OPTION_REVERSE_DIST_MANAGER   |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Supported Transport       |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   /              Reverse Distribution Manager FQDN                /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 3: Reverse Distribution Manager Option

   *  option-code (16 bits): OPTION_REVERSE_DIST_MANAGER, the option
      code for the Reverse Distribution Manager Option (TBD3).

   *  option-len (16 bits): length in octets of the option-data field as
      described in [RFC8415].

   *  Supported Transport (16 bits): defines the supported transport by
      the RDM (see Section 4.4).  Each bit represents a supported
      transport, and a RDM MAY indicate the support of multiple modes.
      The bit for DNS over TLS [RFC7858] MUST be set.

   *  Reverse Distribution Manager FQDN (variable): the FQDN of the RDM
      encoded as described in section 10 of [RFC8415].

4.4.  Supported Transport

   The Supported Transport field of the DHCPv6 option indicates the
   supported transport protocols.  Each bit represents a specific
   transport mechanism.  A bit sets to 1 indicates the associated
   transport protocol is supported.  The corresponding bits are assigned
   as described in Figure 4 and Section 6.

   Bit Position | Transport Protocol |  Mnemonic | Reference
   left to right| Description        |           |
   -------------+--------------------+-----------+-----------
         0      | DNS over TLS       | DoT       | This-RFC
        1-15    | unallocated        |  -        |  -

                       Figure 4: Supported Transport

   DNS over TLS: indicates the support of DNS over TLS as described in
   [RFC7858] and [RFC9103].

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5.  DHCPv6 Behavior

5.1.  DHCPv6 Server Behavior

   Sections 17.2.2 and 18.2 of [RFC8415] govern server operation in
   regards to option assignment.  As a convenience to the reader, we
   mention here that the server will send option foo only if configured
   with specific values for foo and if the client requested it.  In
   particular, when configured the DHCPv6 server sends the Registered
   Homenet Domain Option, Distribution Manager Option, the Reverse
   Distribution Manager Option when requested by the DHCPv6 client by
   including necessary option codes in its ORO.

5.2.  DHCPv6 Client Behavior

   The DHCPv6 client includes Registered Homenet Domain Option,
   Distribution Manager Option, the Reverse Distribution Manager Option
   in an ORO as specified in Sections 18.2.1, 18.2.2, 18.2.4, 18.2.5,
   18.2.6, and 21.7 of [RFC8415].

   Upon receiving a DHCPv6 option described in this document in the
   Reply message, the HNA SHOULD proceed as described in
   [I-D.ietf-homenet-front-end-naming-delegation].

5.3.  DHCPv6 Relay Agent Behavior

   There are no additional requirements for the DHCPv6 Relay agents.

6.  IANA Considerations

6.1.  DHCPv6 Option Codes

   IANA is requested to assign the following new DHCPv6 Option Codes in
   the registry maintained in: https://www.iana.org/assignments/dhcpv6-
   parameters/dhcpv6-parameters.xhtml#dhcpv6-parameters-2.

Value Description                   Client ORO     Singleton Option  Reference
TBD1  OPTION_REGISTERED_DOMAIN       Yes            No               [This-RFC] Section 4.1
TBD2  OPTION_FORWARD_DIST_MANAGER    Yes            Yes              [This-RFC] Section 4.2
TBD3  OPTION_REVERSE_DIST_MANAGER    Yes            Yes              [This-RFC] Section 4.3

6.2.  Supported Transport parameter

   IANA is requested to maintain a new registry of Supported Transport
   parameter in the Distributed Manager Option
   (OPTION_FORWARD_DIST_MANAGER) or the Reverse Distribution Manager
   Option (OPTION_REVERSE_DIST_MANAGER).  The different parameters are
   defined in Figure 4 in Section 4.4.

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   The Name of the registry is: Supported Transport parameter

   The registry description is: The Supported Transport field of the
   DHCPv6 option is a two octet field that indicates the supported
   transport protocols.  Each bit represents a specific transport
   mechanism.

   The parent grouping is Dynamic Host Configuration Protocol for IPv6
   (DHCPv6) at https://www.iana.org/assignments/dhcpv6-parameters/
   dhcpv6-parameters.xhtml#dhcpv6-parameters-2.

   New entry MUST specify the bit position, the Transport Protocol
   Description a Mnemonic and a Reference as defined in Figure 5.

   The initial registry is as specified in Figure 5.

   Changes of the format or policies of the registry is left to the IETF
   via the IESG.

   Future code points are assigned under RFC Required as per [RFC8126].

   Bit Position | Transport Protocol |  Mnemonic | Reference
   left to right| Description        |           |
   -------------+--------------------+-----------+-----------
         0      | DNS over TLS       | DoT       | This-RFC
        1-15    | unallocated        |  -        |  -

                       Figure 5: Supported Transport

7.  Security Considerations

   The security considerations in [RFC8415] are to be considered.  The
   trust associated with the information carried by the DHCPv6 Options
   described in this document is similar to the one associated with the
   IP prefix - when configured via DHCPv6.

8.  Acknowledgments

   We would like to thank Marcin Siodelski, Bernie Volz and Ted Lemon
   for their comments on the design of the DHCPv6 options.  We would
   also like to thank Mark Andrews, Andrew Sullivan and Lorenzo Colliti
   for their remarks on the architecture design.  The designed solution
   has been largely been inspired by Mark Andrews's document
   [I-D.andrews-dnsop-pd-reverse] as well as discussions with Mark.  We
   also thank Ray Hunter and Michael Richardson for its reviews, its
   comments and for suggesting an appropriated terminology.

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9.  Contributors

   The co-authors would like to thank Chris Griffiths and Wouter
   Cloetens that provided a significant contribution in the early
   versions of the document.

10.  References

10.1.  Normative References

   [I-D.ietf-homenet-front-end-naming-delegation]
              Migault, D., Weber, R., Richardson, M., and R. Hunter,
              "Simple Provisioning of Public Names for Residential
              Networks", Work in Progress, Internet-Draft, draft-ietf-
              homenet-front-end-naming-delegation-19, 20 October 2022,
              <https://datatracker.ietf.org/api/v1/doc/document/draft-
              ietf-homenet-front-end-naming-delegation/>.

   [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>.

   [RFC7858]  Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
              and P. Hoffman, "Specification for DNS over Transport
              Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
              2016, <https://www.rfc-editor.org/info/rfc7858>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8415]  Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
              Richardson, M., Jiang, S., Lemon, T., and T. Winters,
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
              RFC 8415, DOI 10.17487/RFC8415, November 2018,
              <https://www.rfc-editor.org/info/rfc8415>.

10.2.  Informative References

   [I-D.andrews-dnsop-pd-reverse]
              Andrews, M., "Automated Delegation of IP6.ARPA reverse
              zones with Prefix Delegation", Work in Progress, Internet-

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              Draft, draft-andrews-dnsop-pd-reverse-02, 4 November 2013,
              <https://www.ietf.org/archive/id/draft-andrews-dnsop-pd-
              reverse-02.txt>.

   [I-D.sury-dnsext-cname-dname]
              Sury, O., "CNAME+DNAME Name Redirection", Work in
              Progress, Internet-Draft, draft-sury-dnsext-cname-dname-
              00, 15 April 2010, <https://www.ietf.org/archive/id/draft-
              sury-dnsext-cname-dname-00.txt>.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC2181]  Elz, R. and R. Bush, "Clarifications to the DNS
              Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
              <https://www.rfc-editor.org/info/rfc2181>.

   [RFC6672]  Rose, S. and W. Wijngaards, "DNAME Redirection in the
              DNS", RFC 6672, DOI 10.17487/RFC6672, June 2012,
              <https://www.rfc-editor.org/info/rfc6672>.

   [RFC7227]  Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and
              S. Krishnan, "Guidelines for Creating New DHCPv6 Options",
              BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014,
              <https://www.rfc-editor.org/info/rfc7227>.

   [RFC7368]  Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
              Weil, "IPv6 Home Networking Architecture Principles",
              RFC 7368, DOI 10.17487/RFC7368, October 2014,
              <https://www.rfc-editor.org/info/rfc7368>.

   [RFC9103]  Toorop, W., Dickinson, S., Sahib, S., Aras, P., and A.
              Mankin, "DNS Zone Transfer over TLS", RFC 9103,
              DOI 10.17487/RFC9103, August 2021,
              <https://www.rfc-editor.org/info/rfc9103>.

Appendix A.  Scenarios and impact on the End User

   This appendix details various scenarios and discuss their impact on
   the end user.  This appendix is not normative and limits the
   description of a limited scope of scenarios that are assumed to be
   representative.  Many other scenarios may be derived from these.

A.1.  Base Scenario

   The base scenario is the one described in Section 3 in which an ISP
   manages the DHCPv6 server, the DM and RDM.

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   The end user subscribes to the ISP (foo), and at subscription time
   registers for foo.example as its Registered Homenet Domain
   foo.example.

   In this scenario, the DHCPv6 server, DM and RDM are managed by the
   ISP so the DHCPv6 server and as such can provide authentication
   credentials of the HNA to enable secure authenticated transaction
   with the DM and the Reverse DM.

   The main advantage of this scenario is that the naming architecture
   is configured automatically and transparently for the end user.  The
   drawbacks are that the end user uses a Registered Homenet Domain
   managed by the ISP and that it relies on the ISP naming
   infrastructure.

A.2.  Third Party Registered Homenet Domain

   This appendix considers the case when the end user wants its home
   network to use example.com not managed by her ISP (foo) as a
   Registered Homenet Domain.  This appendix still considers the ISP
   manages the home network and still provides foo.example as a
   Registered Homenet Domain.

   When the end user buys the domain name example.com, it may request to
   redirect the name example.com to foo.example using static redirection
   with CNAME [RFC2181], [RFC1034], DNAME [RFC6672] or CNAME+DNAME
   [I-D.sury-dnsext-cname-dname].  The only information the end user
   needs to know is the domain name assigned by the ISP.  Once the
   redirection has been configured, the HNA may be changed, the zone can
   be updated as in Appendix A.1 without any additional configuration
   from the end user.

   The main advantage of this scenario is that the end user benefits
   from the Zero Configuration of the Base Scenario Appendix A.1.  Then,
   the end user is able to register for its home network an unlimited
   number of domain names provided by an unlimited number of different
   third party providers.  The drawback of this scenario may be that the
   end user still rely on the ISP naming infrastructure.  Note that the
   only case this may be inconvenient is when the DNS servers provided
   by the ISPs results in high latency.

A.3.  Third Party DNS Infrastructure

   This scenario considers that the end user uses example.com as a
   Registered Homenet Domain, and does not want to rely on the
   authoritative servers provided by the ISP.

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   In this appendix we limit the outsourcing to the DM and Public
   Authoritative Server(s) to a third party.  The Reverse Public
   Authoritative Server(s) and the RDM remain managed by the ISP as the
   IP prefix is managed by the ISP.

   Outsourcing to a third party DM can be performed in the following
   ways:

   1.  Updating the DHCPv6 server Information.  One can imagine a GUI
       interface that enables the end user to modify its profile
       parameters.  Again, this configuration update is done once-for-
       ever.

   2.  Upload the configuration of the DM to the HNA.  In some cases,
       the provider of the CPE router hosting the HNA may be the
       registrar and provide the CPE router already configured.  In
       other cases, the CPE router may request the end user to log into
       the registrar to validate the ownership of the Registered Homenet
       Domain and agree on the necessary credentials to secure the
       communication between the HNA and the DM.  As described in
       [I-D.ietf-homenet-front-end-naming-delegation], such settings
       could be performed in an almost automatic way as to limit the
       necessary interactions with the end user.

A.4.  Multiple ISPs

   This scenario considers a HNA connected to multiple ISPs.

   Suppose the HNA has been configured each of its interfaces
   independently with each ISPS as described in Appendix A.1.  Each ISP
   provides a different Registered Homenet Domain.

   The protocol and DHCPv6 options described in this document are fully
   compatible with a HNA connected to multiple ISPs with multiple
   Registered Homenet Domains.  However, the HNA should be able to
   handle different Registered Homenet Domains.  This is an
   implementation issue which is outside the scope of the current
   document.

   If a HNA is not able to handle multiple Registered Homenet Domains,
   the HNA may remain connected to multiple ISP with a single Registered
   Homenet Domain.  In this case, one entity is chosen to host the
   Registered Homenet Domain.  This entity may be one of the ISP or a
   third party.  Note that having multiple ISPs can be motivated for
   bandwidth aggregation, or connectivity fail-over.  In the case of
   connectivity fail-over, the fail-over concerns the access network and
   a failure of the access network may not impact the core network where
   the DM and Public Authoritative Primaries are hosted.  In that sense,

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   choosing one of the ISP even in a scenario of multiple ISPs may make
   sense.  However, for sake of simplicity, this scenario assumes that a
   third party has been chosen to host the Registered Homenet Domain.
   Configuration is performed as described in Appendix A.2 and
   Appendix A.3.

   With the configuration described in Appendix A.2, the HNA is expect
   to be able to handle multiple Homenet Registered Domain, as the third
   party redirect to one of the ISPs servers.  With the configuration
   described in Appendix A.3, DNS zone are hosted and maintained by the
   third party.  A single DNS(SEC) Homenet Zone is built and maintained
   by the HNA.  This latter configuration is likely to match most HNA
   implementations.

   The protocol and DHCPv6 options described in this document are fully
   compatible with a HNA connected to multiple ISPs.  To configure or
   not and how to configure the HNA depends on the HNA facilities.
   Appendix A.1 and Appendix A.2 require the HNA to handle multiple
   Registered Homenet Domain, whereas Appendix A.3 does not have such
   requirement.

Authors' Addresses

   Daniel Migault
   Ericsson
   8275 Trans Canada Route
   Saint Laurent, QC  4S 0B6
   Canada
   Email: daniel.migault@ericsson.com

   Ralf Weber
   Akamai
   Email: ralf.weber@akamai.com

   Tomek Mrugalski
   Internet Systems Consortium, Inc.
   950 Charter Street
   Redwood City,  94063
   United States of America
   Email: tomasz.mrugalski@gmail.com

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