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+Internet Engineering Task Force (IETF) D. Migault
+Request for Comments: 9527 Ericsson
+Category: Standards Track R. Weber
+ISSN: 2070-1721 Akamai
+ T. Mrugalski
+ ISC
+ January 2024
+
+
+ DHCPv6 Options for the Homenet Naming Authority
+
+Abstract
+
+ This document defines DHCPv6 options so that a Homenet Naming
+ Authority (HNA) can automatically set 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 is an Internet Standards Track document.
+
+ This document is a product of the Internet Engineering Task Force
+ (IETF). It represents the consensus of the IETF community. It has
+ received public review and has been approved for publication by the
+ Internet Engineering Steering Group (IESG). Further information on
+ Internet Standards is available in Section 2 of RFC 7841.
+
+ Information about the current status of this document, any errata,
+ and how to provide feedback on it may be obtained at
+ https://www.rfc-editor.org/info/rfc9527.
+
+Copyright Notice
+
+ Copyright (c) 2024 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
+ 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. Introduction
+ 2. Terminology
+ 3. Procedure Overview
+ 4. DHCPv6 Options
+ 4.1. Registered Homenet Domain Option
+ 4.2. Forward Distribution Manager Option
+ 4.3. Reverse Distribution Manager Server Option
+ 4.4. Supported Transport
+ 5. DHCPv6 Behavior
+ 5.1. DHCPv6 Server Behavior
+ 5.2. DHCPv6 Client Behavior
+ 5.3. DHCPv6 Relay Agent Behavior
+ 6. IANA Considerations
+ 6.1. DHCPv6 Option Codes
+ 6.2. Supported Transport Parameter
+ 7. Security Considerations
+ 8. References
+ 8.1. Normative References
+ 8.2. Informative References
+ Appendix A. Scenarios and Impact on the End User
+ A.1. Base Scenario
+ A.2. Third-Party Registered Homenet Domain
+ A.3. Third-Party DNS Infrastructure
+ A.4. Multiple ISPs
+ Acknowledgments
+ Contributors
+ Authors' Addresses
+
+1. Introduction
+
+ [RFC9526] specifies how an entity designated as the Homenet Naming
+ Authority (HNA) outsources a Public Homenet Zone to a 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 and the associated
+ reverse zone to the home network. 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 home
+ network with a specific domain name designated per a Registered
+ Homenet Domain [RFC9526]. 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 and the 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 [RFC9526].
+
+ 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.
+
+2. 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.
+
+ The reader should be familiar with [RFC9526].
+
+3. Procedure Overview
+
+ This section illustrates how an 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
+ [RFC9526], this section assumes that the HNA and the home network
+ DHCPv6 client are colocated on the Customer Premises Equipment (CPE)
+ router [RFC7368]. Also, note that this is not mandatory, and the
+ DHCPv6 client may remotely instruct the HNA with a protocol that will
+ be standardized in the future. In addition, this section assumes
+ that the responsible entity for the DHCPv6 server is provisioned with
+ the DM and RDM information, which is 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 configuration.
+
+ 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 "Securing the Control Channel"
+ (Section 6.6) of [RFC9526]) by the DM and the RDM. The HNA
+ builds the Homenet Zone (or the Homenet Reverse Zone) and
+ proceeds as described in [RFC9526]. The DHCPv6 options provide
+ the necessary non-optional parameters described in Appendix B of
+ [RFC9526]. The HNA may complement the configurations with
+ additional parameters via means not yet defined. Appendix B of
+ [RFC9526] describes such parameters that may take some specific
+ non-default value.
+
+4. DHCPv6 Options
+
+ 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
+ fully qualified domain name (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 (145).
+
+ 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 Distribution 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 an 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.
+
+ 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 (146).
+
+ 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 bit for DNS over mutually authenticated TLS (DomTLS) MUST be
+ set.
+
+ Distribution Manager FQDN (variable): The FQDN of the DM encoded as
+ described in Section 10 of [RFC8415].
+
+ It is worth noting that the DHCPv6 option specifies the Supported
+ Transport without specifying any explicit port. Unless the HNA and
+ the DM have agreed on using a specific port -- for example, by
+ configuration, or any out-of-band mechanism -- the default port is
+ used and must be specified. The specification of such default port
+ may be defined in the specification of the designated Supported
+ Transport or in any other document. In the case of DomTLS, the
+ default port value is 853 per DNS over TLS [RFC7858] and DNS Zone
+ Transfer over TLS [RFC9103].
+
+ The need to associate the port value to each Supported Transport in
+ the DHCPv6 option has been balanced with the difficulty of handling a
+ list of tuples (transport, port) and the possibility of using a
+ dedicated IP address for the DM in case the default port is already
+ in use.
+
+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.
+
+ 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 (147).
+
+ 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 an RDM MAY indicate the support of multiple modes.
+ The bit for DomTLS [RFC7858] MUST be set.
+
+ Reverse Distribution Manager FQDN (variable): The FQDN of the RDM
+ encoded as described in Section 10 of [RFC8415].
+
+ For the port number associated to the Supported Transport, the same
+ considerations as described in Section 4.2 apply.
+
+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 set to 1 indicates the associated
+ transport protocol is supported. The corresponding bits are assigned
+ as described in Table 2.
+
+ DNS over mutually authenticated TLS (DomTLS): Indicates the support
+ of DNS over TLS [RFC7858] and DNS Zone Transfer over TLS [RFC9103]
+ as described in [RFC9526].
+
+ As an example, the Supported Transport field expressing support for
+ DomTLS looks as follows and has a numeric value of 0x0001:
+
+ 0 1
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | must be zero |1|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+5. DHCPv6 Behavior
+
+5.1. DHCPv6 Server Behavior
+
+ Section 18.3 of [RFC8415] governs server operation regarding 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, and 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 the Registered Homenet Domain Option,
+ Distribution Manager Option, and Reverse Distribution Manager Option
+ in an ORO as specified in Sections 18.2 and 21.7 of [RFC8415].
+
+ Upon receiving a DHCPv6 option, as described in this document, in the
+ Reply message, the HNA SHOULD proceed as described in [RFC9526].
+
+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 has assigned the following new DHCPv6 Option Codes in the
+ "Option Codes" registry maintained at
+ <https://www.iana.org/assignments/dhcpv6-parameters>.
+
+ +=====+=============================+======+===========+===========+
+ |Value| Description |Client| Singleton | Reference |
+ | | |ORO | Option | |
+ +=====+=============================+======+===========+===========+
+ |145 | OPTION_REGISTERED_DOMAIN |Yes | No | RFC 9527, |
+ | | | | | Section |
+ | | | | | 4.1 |
+ +-----+-----------------------------+------+-----------+-----------+
+ |146 | OPTION_FORWARD_DIST_MANAGER |Yes | Yes | RFC 9527, |
+ | | | | | Section |
+ | | | | | 4.2 |
+ +-----+-----------------------------+------+-----------+-----------+
+ |147 | OPTION_REVERSE_DIST_MANAGER |Yes | Yes | RFC 9527, |
+ | | | | | Section |
+ | | | | | 4.3 |
+ +-----+-----------------------------+------+-----------+-----------+
+
+ Table 1: Option Codes Registry
+
+6.2. Supported Transport Parameter
+
+ IANA has created and maintains a new registry called "Supported
+ Transport" under the "Dynamic Host Configuration Protocol for IPv6
+ (DHCPv6)" registry at <https://www.iana.org/assignments/
+ dhcpv6-parameters>. This registry contains Supported Transport
+ parameters 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 Table 2 (Section 6.2).
+
+ 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.
+
+ New entries MUST specify the bit position, the transport protocol
+ description, a mnemonic, and a reference as shown in Table 2.
+
+ Changes to the format or policies of the registry are managed by the
+ IETF via the IESG.
+
+ Future code points are assigned under RFC Required per [RFC8126].
+ The initial registry is as specified in Table 2 below.
+
+ +======================+====================+==========+===========+
+ | Bit Position (least | Transport Protocol | Mnemonic | Reference |
+ | to most significant) | Description | | |
+ +======================+====================+==========+===========+
+ | 0 | DNS over mutually | DomTLS | RFC 9527 |
+ | | authenticated TLS | | |
+ +----------------------+--------------------+----------+-----------+
+ | 1-15 | Unassigned | | |
+ +----------------------+--------------------+----------+-----------+
+
+ Table 2: Supported Transport Registry
+
+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.
+
+ In some cases, the ISP MAY identify the HNA by its wire line (i.e.,
+ physically), which may not require relying on TLS to authenticate the
+ HNA. As the use of TLS is mandatory, it is expected that the HNA
+ will be provisioned with a certificate. In some cases, the HNA may
+ use a self-signed certificate.
+
+8. References
+
+8.1. 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>.
+
+ [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>.
+
+ [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>.
+
+ [RFC9526] Migault, D., Weber, R., Richardson, M., and R. Hunter,
+ "Simple Provisioning of Public Names for Residential
+ Networks", RFC 9526, DOI 10.17487/RFC9526, January 2024,
+ <https://www.rfc-editor.org/info/rfc9526>.
+
+8.2. Informative References
+
+ [CNAME-PLUS-DNAME]
+ Surý, O., "CNAME+DNAME Name Redirection", Work in
+ Progress, Internet-Draft, draft-sury-dnsop-cname-plus-
+ dname-01, 15 July 2018,
+ <https://datatracker.ietf.org/doc/html/draft-sury-dnsop-
+ cname-plus-dname-01>.
+
+ [PD-REVERSE]
+ Andrews, M., "Automated Delegation of IP6.ARPA reverse
+ zones with Prefix Delegation", Work in Progress, Internet-
+ Draft, draft-andrews-dnsop-pd-reverse-02, 5 November 2013,
+ <https://datatracker.ietf.org/doc/html/draft-andrews-
+ dnsop-pd-reverse-02>.
+
+ [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>.
+
+Appendix A. Scenarios and Impact on the End User
+
+ This appendix details various scenarios and discusses 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, as described in Section 3, is one in which an ISP
+ manages the DHCPv6 server, DM, and RDM.
+
+ The end user subscribes to the ISP (foo), and at subscription time,
+ it registers foo.example as its Registered Homenet Domain.
+
+ In this scenario, the DHCPv6 server, DM, and RDM are managed by the
+ ISP, so the DHCPv6 server and 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 where the end user wants its home
+ network to use example.com but does not want it to be managed by the
+ ISP (foo) as a Registered Homenet Domain, and 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 example.com to foo.example using static redirection with
+ CNAME [RFC1034] [RFC2181], DNAME [RFC6672], or CNAME+DNAME
+ [CNAME-PLUS-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, and the zone can be updated
+ as described 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 in Appendix A.1.
+ Then, the end user is able to register an unlimited number of domain
+ names provided by an unlimited number of different third-party
+ providers for its home network. The drawback of this scenario may be
+ that the end user still needs to rely on the ISP naming
+ infrastructure. Note that this may be inconvenient in the case where
+ the DNS servers provided by the ISPs result in high latency.
+
+A.3. Third-Party DNS Infrastructure
+
+ This scenario involves the end user using example.com as a Registered
+ Homenet Domain and not relying on the authoritative servers provided
+ by the ISP.
+
+ In this appendix, we limit the outsourcing of 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 only needs to be
+ performed one time.
+
+ 2. Uploading 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 the registrar may 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 [RFC9526], 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 involves an HNA connected to multiple ISPs.
+
+ Suppose the HNA has configured each of its interfaces independently
+ with each ISP 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 an 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 this document.
+
+ If an HNA is not able to handle multiple Registered Homenet Domains,
+ the HNA may remain connected to multiple ISPs with a single
+ Registered Homenet Domain. In this case, one entity is chosen to
+ host the Registered Homenet Domain. This entity may be an ISP or a
+ third party. Note that having multiple ISPs can be motivation for
+ bandwidth aggregation or connectivity failover. In the case of
+ connectivity failover, the failover 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,
+ choosing one of the ISPs even in a scenario of multiple ISPs may make
+ sense. However, for the 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 Appendices A.2
+ and A.3.
+
+ With the configuration described in Appendix A.2, the HNA is expected
+ to be able to handle multiple Registered Homenet Domains as the
+ third-party redirect to one of the ISP's servers. With the
+ configuration described in Appendix A.3, DNS zones 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 an HNA connected to multiple ISPs. Whether to
+ configure the HNA or not, and how to configure the HNA, depends on
+ the HNA facilities. Appendices A.1 and A.2 require the HNA to handle
+ multiple Registered Homenet Domains, whereas Appendix A.3 does not
+ have such a requirement.
+
+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 inspired by Mark Andrews's document [PD-REVERSE] as
+ well as discussions with Mark. We also thank Ray Hunter and Michael
+ Richardson for their reviews and comments and for suggesting
+ appropriate terminology.
+
+Contributors
+
+ The coauthors would like to thank Chris Griffiths and Wouter Cloetens
+ for providing significant contributions to the early draft versions
+ of this document.
+
+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.
+ PO Box 360
+ Newmarket, NH 03857
+ United States of America
+ Email: tomasz.mrugalski@gmail.com