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Basic Requirements for IPv6 Customer Edge Routers
draft-winters-v6ops-rfc7084bis-01

Document Type Active Internet-Draft (individual)
Authors Gábor Lencse , Jordi Palet Martinez , Ben Patton , Timothy Winters
Last updated 2023-11-07
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draft-winters-v6ops-rfc7084bis-01
Network Working Group                                          G. Lencse
Internet-Draft                                         J. Palet Martinez
Obsoletes: 7084 (if approved)                           The IPv6 Company
Intended status: Informational                                 P. Patton
Expires: 10 May 2024                                             UNH-IOL
                                                              T. Winters
                                                                 QA Cafe
                                                         7 November 2023

           Basic Requirements for IPv6 Customer Edge Routers
                   draft-winters-v6ops-rfc7084bis-01

Abstract

   This document specifies requirements for an IPv6 Customer Edge (CE)
   router.  Specifically, the current version of this document focuses
   on the basic provisioning of an IPv6 CE router and the provisioning
   of IPv6 hosts attached to it.  The document obsoletes RFC 7084.

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 10 May 2024.

Copyright Notice

   Copyright (c) 2023 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.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Current IPv4 End-User Network Architecture  . . . . . . .   4
     3.2.  IPv6 End-User Network Architecture  . . . . . . . . . . .   5
       3.2.1.  Local Communication . . . . . . . . . . . . . . . . .   6
   4.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  General Requirements  . . . . . . . . . . . . . . . . . .   6
     4.2.  WAN-Side Configuration  . . . . . . . . . . . . . . . . .   7
     4.3.  LAN-Side Configuration  . . . . . . . . . . . . . . . . .  11
     4.4.  Security Considerations . . . . . . . . . . . . . . . . .  13
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14
   7.  Appendix: Changes from RFC 7084 . . . . . . . . . . . . . . .  15
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   This document defines basic IPv6 features for a residential or small-
   office router, referred to as an "IPv6 CE router", in order to
   establish an industry baseline for features to be implemented on such
   a router.

   These routers typically also support IPv4.

   Mixed environments of dual-stack hosts and IPv6-only hosts (behind
   the CE router) can be more complex if the IPv6-only devices are using
   a translator to access IPv4 servers [RFC6144].  Support for such
   mixed environments is not in scope of this document.

   This document specifies how an IPv6 CE router automatically
   provisions its WAN interface, acquires address space for provisioning
   of its LAN interfaces, and fetches other configuration information

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   from the service provider network.  Automatic provisioning of more
   complex topology than a single router with multiple LAN interfaces is
   out of scope for this document.

   See [RFC4779] for a discussion of options available for deploying
   IPv6 in service provider access networks.

   The document does not cover the IP transition technologies available
   to IPv6 CE Router.  For information about IP transition technologies
   please refer to [RFC8585].

1.1.  Requirements Language

   Take careful note: Unlike other IETF documents, the key words "MUST",
   "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and "OPTIONAL" in this document are not used as
   described in RFC 2119 [RFC2119].  This document uses these keywords
   not strictly for the purpose of interoperability, but rather for the
   purpose of establishing industry-common baseline functionality.  As
   such, the document points to several other specifications (preferable
   in RFC or stable form) to provide additional guidance to implementers
   regarding any protocol implementation required to produce a
   successful CE router that interoperates successfully with a
   particular subset of currently deploying and planned common IPv6
   access networks.

2.  Terminology

   End-User Network          one or more links attached to the IPv6 CE
                             router that connect IPv6 hosts.

   IPv6 Customer Edge Router  a node intended for home or small-office
                             use that forwards IPv6 packets not
                             explicitly addressed to itself.  The IPv6
                             CE router connects the end-user network to
                             a service provider network.

   IPv6 Host                 any device implementing an IPv6 stack
                             receiving IPv6 connectivity through the
                             IPv6 CE router.

   LAN Interface             an IPv6 CE router's attachment to a link in
                             the end-user network.  Examples are
                             Ethernet (simple or bridged), 802.11
                             wireless, or other LAN technologies.  An
                             IPv6 CE router may have one or more
                             network-layer LAN interfaces.

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   Service Provider          an entity that provides access to the
                             Internet.  In this document, a service
                             provider specifically offers Internet
                             access using IPv6, and it may also offer
                             IPv4 Internet access.  The service provider
                             can provide such access over a variety of
                             different transport methods such as DSL,
                             cable, wireless, and others.

   WAN Interface             an IPv6 CE router's attachment to a link
                             used to provide connectivity to the service
                             provider network; example link technologies
                             include Ethernet (simple or bridged), PPP
                             links, Frame Relay, or ATM networks, as
                             well as Internet-layer (or higher-layer)
                             "tunnels", such as tunnels over IPv4 or
                             IPv6 itself.

3.  Architecture

3.1.  Current IPv4 End-User Network Architecture

   An end-user network will likely support both IPv4 and IPv6.  It is
   not expected that an end user will change their existing network
   topology with the introduction of IPv6.  There are some differences
   in how IPv6 works and is provisioned; these differences have
   implications for the network architecture.  A typical IPv4 end-user
   network consists of a "plug and play" router with NAT functionality
   and a single link behind it, connected to the service provider
   network.

   A typical IPv4 NAT deployment by default blocks all incoming
   connections.  Opening of ports is typically allowed using a Universal
   Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some
   other firewall control protocol.

   Another consequence of using private address space in the end-user
   network is that it provides stable addressing; that is, it never
   changes even when you change service providers, and the addresses are
   always there even when the WAN interface is down or the customer edge
   router has not yet been provisioned.

   Many existing routers support dynamic routing (which learns routes
   from other routers), and advanced end-users can build arbitrary,
   complex networks using manual configuration of address prefixes
   combined with a dynamic routing protocol.

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3.2.  IPv6 End-User Network Architecture

   The end-user network architecture for IPv6 should provide equivalent
   or better capabilities and functionality than the current IPv4
   architecture.

   The end-user network is a stub network.  Figure 1 illustrates the
   model topology for the end-user network.

                     +-------+-------+                      \
                     |   Service     |                       \
                     |   Provider    |                        | Service
                     |    Router     |                        | Provider
                     +-------+-------+                        | Network
                             |                               /
                             | Customer                     /
                             | Internet Connection         /
                             |
                      +------+--------+                    \
                      |     IPv6      |                     \
                      | Customer Edge |                      \
                      |    Router     |                      /
                      +---+-------+-+-+                     /
          Network A       |       |   Network B            | End-User
    ---+-------------+----+-    --+--+-------------+---    | Network(s)
       |             |               |             |        \
   +----+-----+ +-----+----+     +----+-----+ +-----+----+   \
   |IPv6 Host | |IPv6 Host |     | IPv6 Host| |IPv6 Host |   /
   |          | |          |     |          | |          |  /
   +----------+ +-----+----+     +----------+ +----------+ /

             Figure 1: An Example of a Typical End-User Network

   This architecture describes the:

   *  Basic capabilities of an IPv6 CE router

   *  Provisioning of the WAN interface connecting to the service
      provider

   *  Provisioning of the LAN interfaces

   For IPv6 multicast traffic, the IPv6 CE router may act as a Multicast
   Listener Discovery (MLD) proxy [RFC4605] and may support a dynamic
   multicast routing protocol.

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   The IPv6 CE router may be manually configured in an arbitrary
   topology with a dynamic routing protocol.  Automatic provisioning and
   configuration are described for a single IPv6 CE router only.

3.2.1.  Local Communication

   Link-local IPv6 addresses are used by hosts communicating on a single
   link.  Unique Local IPv6 Unicast Addresses (ULAs) [RFC4193] are used
   by hosts communicating within the end-user network across multiple
   links, but without requiring the application to use a globally
   routable address.  The IPv6 CE router defaults to acting as the
   demarcation point between two networks by providing a ULA boundary, a
   multicast zone boundary, and ingress and egress traffic filters.

   At the time of this writing, several host implementations do not
   handle the case where they have an IPv6 address configured and no
   IPv6 connectivity, either because the address itself has a limited
   topological reachability (e.g., ULA) or because the IPv6 CE router is
   not connected to the IPv6 network on its WAN interface.  To support
   host implementations that do not handle multihoming in a multi-prefix
   environment [RFC7157], the IPv6 CE router should not, as detailed in
   the requirements below, advertise itself as a default router on the
   LAN interface(s) when it does not have IPv6 connectivity on the WAN
   interface or when it is not provisioned with IPv6 addresses.  For
   local IPv6 communication, the mechanisms specified in [RFC4191] are
   used.

   ULA addressing is useful where the IPv6 CE router has multiple LAN
   interfaces with hosts that need to communicate with each other.  If
   the IPv6 CE router has only a single LAN interface (IPv6 link), then
   link-local addressing can be used instead.

   Coexistence with IPv4 requires any IPv6 CE router(s) on the LAN to
   conform to these recommendations, especially requirements ULA-5 and
   L-4 below.

4.  Requirements

4.1.  General Requirements

   The IPv6 CE router is responsible for implementing IPv6 routing; that
   is, the IPv6 CE router must look up the IPv6 destination address in
   its routing table to decide to which interface it should send the
   packet.

   In this role, the IPv6 CE router is responsible for ensuring that
   traffic using its ULA addressing does not go out the WAN interface
   and does not originate from the WAN interface.

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   G-1:  An IPv6 CE router is an IPv6 node according to the IPv6 Node
         Requirements specification [RFC8504].

   G-2:  The IPv6 CE router MUST implement ICMPv6 according to
         [RFC4443].  In particular, point-to-point links MUST be handled
         as described in Section 3.1 of [RFC4443].

   G-3:  The IPv6 CE router MUST NOT forward any IPv6 traffic between
         its LAN interface(s) and its WAN interface until the router has
         successfully completed the IPv6 address and the delegated
         prefix acquisition process.

   G-4:  By default, an IPv6 CE router that has no default router(s) on
         its WAN interface MUST NOT advertise itself as an IPv6 default
         router on its LAN interfaces.  That is, the "Router Lifetime"
         field is set to zero in all Router Advertisement messages it
         originates [RFC4861].

   G-5:  By default, if the IPv6 CE router is an advertising router and
         loses its IPv6 default router(s) and/or detects loss of
         connectivity on the WAN interface, it MUST explicitly
         invalidate itself as an IPv6 default router on each of its
         advertising interfaces by immediately transmitting one or more
         Router Advertisement messages with the "Router Lifetime" field
         set to zero [RFC4861].

4.2.  WAN-Side Configuration

   The IPv6 CE router will need to support connectivity to one or more
   access network architectures.  This document describes an IPv6 CE
   router that is not specific to any particular architecture or service
   provider and that supports all commonly used architectures.

   IPv6 Neighbor Discovery and DHCPv6 protocols operate over any type of
   IPv6-supported link layer, and there is no need for a link-layer-
   specific configuration protocol for IPv6 network-layer configuration
   options as in, e.g., PPP IP Control Protocol (IPCP) for IPv4.  This
   section makes the assumption that the same mechanism will work for
   any link layer, be it Ethernet, the Data Over Cable Service Interface
   Specification (DOCSIS), PPP, or others.

   WAN-side requirements:

   W-1:  When the router is attached to the WAN interface link, it MUST
         act as an IPv6 host for the purposes of stateless [RFC4862] or
         stateful [RFC8415] interface address assignment.

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   W-2:  The IPv6 CE router MUST generate a link-local address and
         finish Duplicate Address Detection according to [RFC4862] prior
         to sending any Router Solicitations on the interface.  The
         source address used in the subsequent Router Solicitation MUST
         be the link-local address on the WAN interface.

   W-3:  Absent other routing information, the IPv6 CE router MUST use
         Router Discovery as specified in [RFC4861] to discover a
         default router(s) and install a default route(s) in its routing
         table with the discovered router's address as the next hop.

   W-4:  The router MUST act as a requesting router for the purposes of
         DHCPv6 prefix delegation ([RFC8415]).

   W-5:  The IPv6 CE router MUST use a persistent DHCP Unique Identifier
         (DUID) for DHCPv6 messages.  The DUID MUST NOT change between
         network-interface resets or IPv6 CE router reboots.

   W-6:  The WAN interface of the CE router SHOULD support a Port
         Control Protocol (PCP) client as specified in [RFC6887] for use
         by applications on the CE router.  The PCP client SHOULD follow
         the procedure specified in Section 8.1 of [RFC6887] to discover
         its PCP server.  This document takes no position on whether
         such functionality is enabled by default or mechanisms by which
         users would configure the functionality.  Handling PCP requests
         from PCP clients in the LAN side of the CE router is out of
         scope.

   Link-layer requirements:

   WLL-1:  If the WAN interface supports Ethernet encapsulation, then
           the IPv6 CE router MUST support IPv6 over Ethernet [RFC2464].

   WLL-2:  If the WAN interface supports PPP encapsulation, the IPv6 CE
           router MUST support IPv6 over PPP [RFC5072].

   WLL-3:  If the WAN interface supports PPP encapsulation, in a dual-
           stack environment with IPCP and IPV6CP running over one PPP
           logical channel, the Network Control Protocols (NCPs) MUST be
           treated as independent of each other and start and terminate
           independently.

   Address assignment requirements:

   WAA-1:   The IPv6 CE router MUST support Stateless Address
            Autoconfiguration (SLAAC) [RFC4862].

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   WAA-2:   The IPv6 CE router MUST follow the recommendations in
            Section 4 of [RFC5942], and in particular the handling of
            the L flag in the Router Advertisement Prefix Information
            option.

   WAA-3:   The IPv6 CE router MUST support DHCPv6 [RFC8415] client
            behavior.

   WAA-4:   The IPv6 CE router MUST be able to support the following
            DHCPv6 options: Identity Association for Non-temporary
            Address (IA_NA), Reconfigure Accept [RFC8415], and
            DNS_SERVERS [RFC3646].  The IPv6 CE router SHOULD be able to
            support the DNS Search List (DNSSL) option as specified in
            [RFC3646].

   WAA-5:   The IPv6 CE router SHOULD implement the Network Time
            Protocol (NTP) as specified in [RFC5905] to provide a time
            reference common to the service provider for other
            protocols, such as DHCPv6, to use.  If the CE router
            implements NTP, it requests the NTP Server DHCPv6 option
            [RFC5908] and uses the received list of servers as primary
            time reference, unless explicitly configured otherwise.  LAN
            side support of NTP is out of scope for this document.

   WAA-6:   If the IPv6 CE router receives a Router Advertisement
            message (described in [RFC4861]) with the M flag set to 1,
            the IPv6 CE router MUST do DHCPv6 address assignment
            (request an IA_NA option).

   WAA-7:   If the IPv6 CE router does not acquire a global IPv6
            address(es) from either SLAAC or DHCPv6, then it MUST create
            a global IPv6 address(es) from its delegated prefix(es) and
            configure those on one of its internal virtual network
            interfaces, unless configured to require a global IPv6
            address on the WAN interface.

   WAA-8:   The CE router MUST support the SOL_MAX_RT option [RFC8415]
            and request the SOL_MAX_RT option in an Option Request
            Option (ORO).

   WAA-9:   As a router, the IPv6 CE router MUST follow the weak host
            (Weak End System) model [RFC1122].  When originating packets
            from an interface, it will use a source address from another
            one of its interfaces if the outgoing interface does not
            have an address of suitable scope.

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   WAA-10:  The IPv6 CE router SHOULD implement the Information Refresh
            Time option and associated client behavior as specified in
            [RFC8415].

   WAA-11:  The IPv6 CE Router MUST NOT use an EUI-64 based address as
            discussed in [RFC7721].  IPv6 CE Router SHOULD follow
            [RFC8064] when generating an IPv6 address.

   Prefix delegation requirements:

   WPD-1:  The IPv6 CE router MUST support DHCPv6 prefix delegation
           requesting router behavior as specified in [RFC8415]
           (Identity Association for Prefix Delegation (IA_PD) option).

   WPD-2:  The IPv6 CE router MAY indicate as a hint to the delegating
           router the size of the prefix it requires.  If so, it MUST
           ask for a prefix large enough to assign one /64 for each of
           its interfaces, rounded up to the nearest nibble, and SHOULD
           be configurable to ask for more.

   WPD-3:  The IPv6 CE router MUST be prepared to accept a delegated
           prefix size different from what is given in the hint.  If the
           delegated prefix is too small to address all of its
           interfaces, the IPv6 CE router SHOULD log a system management
           error.  [RFC6177] covers the recommendations for service
           providers for prefix allocation sizes.

   WPD-4:  By default, the IPv6 CE router MUST initiate DHCPv6 prefix
           delegation when either the M or O flags are set to 1 in a
           received Router Advertisement (RA) message.  Behavior of the
           CE router to use DHCPv6 prefix delegation when the CE router
           has not received any RA or received an RA with the M and the
           O bits set to zero is out of scope for this document.

   WPD-5:  Any packet received by the CE router with a destination
           address in the prefix(es) delegated to the CE router but not
           in the set of prefixes assigned by the CE router to the LAN
           must be dropped.  In other words, the next hop for the
           prefix(es) delegated to the CE router should be the null
           destination.  This is necessary to prevent forwarding loops
           when some addresses covered by the aggregate are not
           reachable [RFC4632].

           (a)  The IPv6 CE router SHOULD send an ICMPv6 Destination
                Unreachable message in accordance with Section 3.1 of
                [RFC4443] back to the source of the packet, if the
                packet is to be dropped due to this rule.

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   WPD-6:  If the IPv6 CE router requests both an IA_NA and an IA_PD
           option in DHCPv6, it MUST accept an IA_PD option in DHCPv6
           Advertise/Reply messages, even if the message does not
           contain any addresses, unless configured to only obtain its
           WAN IPv6 address via DHCPv6; see [RFC8415].

   WPD-7:  By default, an IPv6 CE router MUST NOT initiate any dynamic
           routing protocol on its WAN interface.

   WPD-8:  The IPv6 CE router SHOULD support the [RFC6603] Prefix
           Exclude option.

4.3.  LAN-Side Configuration

   The IPv6 CE router distributes configuration information obtained
   during WAN interface provisioning to IPv6 hosts and assists IPv6
   hosts in obtaining IPv6 addresses.  It also supports connectivity of
   these devices in the absence of any working WAN interface.

   An IPv6 CE router is expected to support an IPv6 end-user network and
   IPv6 hosts that exhibit the following characteristics:

   1.  Link-local addresses may be insufficient for allowing IPv6
       applications to communicate with each other in the end-user
       network.  The IPv6 CE router will need to enable this
       communication by providing globally scoped unicast addresses or
       ULAs [RFC4193], whether or not WAN connectivity exists.

   2.  IPv6 hosts should be capable of using SLAAC and may be capable of
       using DHCPv6 for acquiring their addresses.

   3.  IPv6 hosts may use DHCPv6 for other configuration information,
       such as the DNS_SERVERS option for acquiring DNS information.

   Unless otherwise specified, the following requirements apply to the
   IPv6 CE router's LAN interfaces only.

   ULA requirements:

   ULA-1:  The IPv6 CE router SHOULD be capable of generating a ULA
           prefix [RFC4193].

   ULA-2:  An IPv6 CE router with a ULA prefix MUST maintain this prefix
           consistently across reboots.

   ULA-3:  The value of the ULA prefix SHOULD be configurable.

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   ULA-4:  By default, the IPv6 CE router MUST act as a site border
           router according to Section 4.3 of [RFC4193] and filter
           packets with local IPv6 source or destination addresses
           accordingly.

   ULA-5:  An IPv6 CE router MUST NOT advertise itself as a default
           router with a Router Lifetime greater than zero whenever all
           of its configured and delegated prefixes are ULA prefixes.

   LAN requirements:

   L-1:   The IPv6 CE router MUST support router behavior according to
          Neighbor Discovery for IPv6 [RFC4861].

   L-2:   The IPv6 CE router MUST assign a separate /64 from its
          delegated prefix(es) (and ULA prefix if configured to provide
          ULA addressing) for each of its LAN interfaces.

   L-3:   An IPv6 CE router MUST advertise itself as a router for the
          delegated prefix(es) (and ULA prefix if configured to provide
          ULA addressing) using the "Route Information Option" specified
          in Section 2.3 of [RFC4191].  This advertisement is
          independent of having or not having IPv6 connectivity on the
          WAN interface.

   L-4:   An IPv6 CE router MUST NOT advertise itself as a default
          router with a Router Lifetime [RFC4861] greater than zero if
          it has no prefixes configured or delegated to it.

   L-5:   The IPv6 CE router MUST make each LAN interface an advertising
          interface according to [RFC4861].

   L-6:   In Router Advertisement messages ([RFC4861]), the Prefix
          Information option's A and L flags MUST be set to 1 by
          default.

   L-7:   The A and L flags' ([RFC4861]) settings SHOULD be user
          configurable.

   L-8:   The IPv6 CE router MUST support a DHCPv6 server capable of
          IPv6 address assignment according to OR a stateless DHCPv6
          server according to [RFC8415] on its LAN interfaces.

   L-9:   Unless the IPv6 CE router is configured to support the DHCPv6
          IA_NA option, it SHOULD set the M flag to zero and the O flag
          to 1 in its Router Advertisement messages [RFC4861].

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   L-10:  The IPv6 CE router MUST support providing DNS information in
          the DHCPv6 DNS_SERVERS and DOMAIN_LIST options [RFC3646].

   L-11:  The IPv6 CE router MUST support providing DNS information in
          the Router Advertisement Recursive DNS Server (RDNSS) and DNS
          Search List options.  Both options are specified in [RFC8106].

   L-12:  The IPv6 CE router SHOULD make available a subset of DHCPv6
          options (as listed in Section 21 of [RFC8415]) received from
          the DHCPv6 client on its WAN interface to its LAN-side DHCPv6
          server.

   L-13:  If the delegated prefix changes, i.e., the current prefix is
          replaced with a new prefix without any overlapping time
          period, then the IPv6 CE router MUST immediately advertise the
          old prefix with a Preferred Lifetime of zero and a Valid
          Lifetime of either a) zero or b) the lower of the current
          Valid Lifetime and two hours (which must be decremented in
          real time) in a Router Advertisement message as described in
          Section 5.5.3, (e) of [RFC4862].

   L-14:  The IPv6 CE router MUST send an ICMPv6 Destination Unreachable
          message, code 5 (Source address failed ingress/egress policy)
          for packets forwarded to it that use an address from a prefix
          that has been invalidated.

4.4.  Security Considerations

   It is considered a best practice to filter obviously malicious
   traffic (e.g., spoofed packets, "Martian" addresses, etc.).  Thus,
   the IPv6 CE router ought to support basic stateless egress and
   ingress filters.  The CE router is also expected to offer mechanisms
   to filter traffic entering the customer network; however, the method
   by which vendors implement configurable packet filtering is beyond
   the scope of this document.

   Security requirements:

   S-1:  The IPv6 CE router SHOULD support [RFC6092].  In particular,
         the IPv6 CE router SHOULD support functionality sufficient for
         implementing the set of recommendations in [RFC6092],
         Section 4.  This document takes no position on whether such
         functionality is enabled by default or mechanisms by which
         users would configure it.

   S-2:  The IPv6 CE router MUST support ingress filtering in accordance
         with BCP 38 [RFC2827].

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   S-3:  If the IPv6 CE router firewall is configured to filter incoming
         tunneled data, the firewall SHOULD provide the capability to
         filter decapsulated packets from a tunnel.

5.  Acknowledgements

   The following people have participated as co-authors or provided
   substantial contributionas to the orginal RFC 7084 document: Ralph
   Droms, Kirk Erichsen, Fred Baker, Jason Weil, Lee Howard, Jean-
   Francois Tremblay, Yiu Lee, John Jason Brzozowski, and Heather
   Kirksey.  Thanks to Ole Troan for editorship in the original RFC 6204
   document.

   Thanks to the following people (in alphabetical order) for their
   guidance and feedback:

   Mikael Abrahamsson, Tore Anderson, Merete Asak, Rajiv Asati, Scott
   Beuker, Mohamed Boucadair, Rex Bullinger, Brian Carpenter, Tassos
   Chatzithomaoglou, Lorenzo Colitti, Remi Denis-Courmont, Gert Doering,
   Alain Durand, Katsunori Fukuoka, Brian Haberman, Tony Hain, Thomas
   Herbst, Ray Hunter, Joel Jaeggli, Kevin Johns, Erik Kline, Stephen
   Kramer, Victor Kuarsingh, Francois-Xavier Le Bail, Arifumi Matsumoto,
   David Miles, Shin Miyakawa, Jean-Francois Mule, Michael Newbery,
   Carlos Pignataro, John Pomeroy, Antonio Querubin, Daniel Roesen,
   Hiroki Sato, Teemu Savolainen, Matt Schmitt, David Thaler, Mark
   Townsley, Sean Turner, Bernie Volz, Dan Wing, Timothy Winters, James
   Woodyatt, Carl Wuyts, and Cor Zwart.

   This document is based in part on CableLabs' eRouter specification.
   The authors wish to acknowledge the additional contributors from the
   eRouter team:

   Ben Bekele, Amol Bhagwat, Ralph Brown, Eduardo Cardona, Margo Dolas,
   Toerless Eckert, Doc Evans, Roger Fish, Michelle Kuska, Diego
   Mazzola, John McQueen, Harsh Parandekar, Michael Patrick, Saifur
   Rahman, Lakshmi Raman, Ryan Ross, Ron da Silva, Madhu Sudan, Dan
   Torbet, and Greg White.

6.  Contributors

   The following people have participated as co-authors or provided
   substantial contributions to this document: Tim Carlin and Marion
   Dillon.

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7.  Appendix: Changes from RFC 7084

   There have been many editorial clarifications as well as significant
   additions and updates.  While this section highlights some of the
   changes, readers should not rely on this section for a comprehensive
   list of all changes.

   1.  Updated to use RFC 8585 for transition technologies.

   2.  Removed transition technologies 6RD and DS-Lite requirements.

   3.  Updated to use RFC 8415 for DHCPv6

   4.  Updated to use RFC 7157 for mutlihoming discussion.

   5.  Updated to use RFC 8106 for DNS options in Router Advertisements.

   6.  Updated to use RFC 8405 for IPv6 node requirements.

   7.  Updated S-2 requirement to a MUST to prevent spoofing attacks.

   8.  Added a requirement to not utilize EUI-64 address.

8.  References

8.1.  Normative References

   [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
              Communication Layers", STD 3, RFC 1122,
              DOI 10.17487/RFC1122, October 1989,
              <https://www.rfc-editor.org/info/rfc1122>.

   [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>.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
              <https://www.rfc-editor.org/info/rfc2464>.

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
              May 2000, <https://www.rfc-editor.org/info/rfc2827>.

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   [RFC3646]  Droms, R., Ed., "DNS Configuration options for Dynamic
              Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
              DOI 10.17487/RFC3646, December 2003,
              <https://www.rfc-editor.org/info/rfc3646>.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
              November 2005, <https://www.rfc-editor.org/info/rfc4191>.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
              <https://www.rfc-editor.org/info/rfc4193>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC4605]  Fenner, B., He, H., Haberman, B., and H. Sandick,
              "Internet Group Management Protocol (IGMP) / Multicast
              Listener Discovery (MLD)-Based Multicast Forwarding
              ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605,
              August 2006, <https://www.rfc-editor.org/info/rfc4605>.

   [RFC4632]  Fuller, V. and T. Li, "Classless Inter-domain Routing
              (CIDR): The Internet Address Assignment and Aggregation
              Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
              2006, <https://www.rfc-editor.org/info/rfc4632>.

   [RFC4779]  Asadullah, S., Ahmed, A., Popoviciu, C., Savola, P., and
              J. Palet, "ISP IPv6 Deployment Scenarios in Broadband
              Access Networks", RFC 4779, DOI 10.17487/RFC4779, January
              2007, <https://www.rfc-editor.org/info/rfc4779>.

   [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>.

   [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>.

   [RFC5072]  Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6
              over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007,
              <https://www.rfc-editor.org/info/rfc5072>.

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   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <https://www.rfc-editor.org/info/rfc5905>.

   [RFC5908]  Gayraud, R. and B. Lourdelet, "Network Time Protocol (NTP)
              Server Option for DHCPv6", RFC 5908, DOI 10.17487/RFC5908,
              June 2010, <https://www.rfc-editor.org/info/rfc5908>.

   [RFC5942]  Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet
              Model: The Relationship between Links and Subnet
              Prefixes", RFC 5942, DOI 10.17487/RFC5942, July 2010,
              <https://www.rfc-editor.org/info/rfc5942>.

   [RFC6092]  Woodyatt, J., Ed., "Recommended Simple Security
              Capabilities in Customer Premises Equipment (CPE) for
              Providing Residential IPv6 Internet Service", RFC 6092,
              DOI 10.17487/RFC6092, January 2011,
              <https://www.rfc-editor.org/info/rfc6092>.

   [RFC6144]  Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
              IPv4/IPv6 Translation", RFC 6144, DOI 10.17487/RFC6144,
              April 2011, <https://www.rfc-editor.org/info/rfc6144>.

   [RFC6177]  Narten, T., Huston, G., and L. Roberts, "IPv6 Address
              Assignment to End Sites", BCP 157, RFC 6177,
              DOI 10.17487/RFC6177, March 2011,
              <https://www.rfc-editor.org/info/rfc6177>.

   [RFC6603]  Korhonen, J., Ed., Savolainen, T., Krishnan, S., and O.
              Troan, "Prefix Exclude Option for DHCPv6-based Prefix
              Delegation", RFC 6603, DOI 10.17487/RFC6603, May 2012,
              <https://www.rfc-editor.org/info/rfc6603>.

   [RFC6887]  Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
              P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
              DOI 10.17487/RFC6887, April 2013,
              <https://www.rfc-editor.org/info/rfc6887>.

   [RFC7157]  Troan, O., Ed., Miles, D., Matsushima, S., Okimoto, T.,
              and D. Wing, "IPv6 Multihoming without Network Address
              Translation", RFC 7157, DOI 10.17487/RFC7157, March 2014,
              <https://www.rfc-editor.org/info/rfc7157>.

   [RFC7721]  Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
              Considerations for IPv6 Address Generation Mechanisms",
              RFC 7721, DOI 10.17487/RFC7721, March 2016,
              <https://www.rfc-editor.org/info/rfc7721>.

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   [RFC8064]  Gont, F., Cooper, A., Thaler, D., and W. Liu,
              "Recommendation on Stable IPv6 Interface Identifiers",
              RFC 8064, DOI 10.17487/RFC8064, February 2017,
              <https://www.rfc-editor.org/info/rfc8064>.

   [RFC8106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 8106, DOI 10.17487/RFC8106, March 2017,
              <https://www.rfc-editor.org/info/rfc8106>.

   [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>.

   [RFC8504]  Chown, T., Loughney, J., and T. Winters, "IPv6 Node
              Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
              January 2019, <https://www.rfc-editor.org/info/rfc8504>.

   [RFC8585]  Palet Martinez, J., Liu, H. M.-H., and M. Kawashima,
              "Requirements for IPv6 Customer Edge Routers to Support
              IPv4-as-a-Service", RFC 8585, DOI 10.17487/RFC8585, May
              2019, <https://www.rfc-editor.org/info/rfc8585>.

8.2.  Informative References

   [UPnP-IGD] Forum, U., "InternetGatewayDevice:2 Device Template
              Version 1.01", December 2010,
              <http://upnp.org/specs/gw/igd2/>.

Authors' Addresses

   Gabor Lencse
   The IPv6 Company
   Gyor
   Egyetem ter 1.
   Hungary
   Email: lencse@sze.hu

   Jordi Palet Martinez
   The IPv6 Company
   Molino de la Navata, 75
   La Navata - Galapagar, Madrid
   Spain
   Email: jordi.palet@theipv6company.com
   URI:   http://www.theipv6company.com/

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   Ben Patton
   University of New Hampshire, Interoperability Lab (UNH-IOL)
   Durham, NH
   United States
   Email: bpatton@iol.unh.edu

   Timothy Winters
   QA Cafe
   100 Main Street, Suite #212
   Dover, NH 03820
   United States of America
   Email: tim@qacafe.com

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