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Versions: (draft-v6ops-rfc7084-bis) 00 01 02 03 04

IPv6 Operations (v6ops)                                J. Palet Martinez
Internet-Draft                                         Consulintel, S.L.
Obsoletes: 7084 (if approved)                              June 11, 2017
Intended status: Informational
Expires: December 13, 2017


           Basic Requirements for IPv6 Customer Edge Routers
                    draft-ietf-v6ops-rfc7084-bis-04

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 and the support of HNCP ([RFC7788]) for
   automated provisioning of downstream routers.  The document also
   covers several transition technologies, as required in a world where
   IPv4 addresses are no longer available, so hosts in the customer LANs
   with IPv4-only or IPv6-only applications or devices, requiring to
   communicate with IPv4-only services at the Internet, are able to do
   so.  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 http://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 December 13, 2017.

Copyright Notice

   Copyright (c) 2017 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
   (http://trustee.ietf.org/license-info) in effect on the date of



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   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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Current IPv4 End-User Network Architecture  . . . . . . .   6
     4.2.  IPv6 End-User Network Architecture  . . . . . . . . . . .   7
       4.2.1.  Local Communication . . . . . . . . . . . . . . . . .   9
   5.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  General Requirements  . . . . . . . . . . . . . . . . . .   9
     5.2.  WAN-Side Configuration  . . . . . . . . . . . . . . . . .  10
     5.3.  LAN-Side Configuration  . . . . . . . . . . . . . . . . .  14
     5.4.  Transition Technologies Support . . . . . . . . . . . . .  16
       5.4.1.  IPv4 Service Continuity in Customer LANs  . . . . . .  16
         5.4.1.1.  464XLAT . . . . . . . . . . . . . . . . . . . . .  16
         5.4.1.2.  Dual-Stack Lite (DS-Lite) . . . . . . . . . . . .  17
         5.4.1.3.  Lightweight 4over6 (lw4o6)  . . . . . . . . . . .  18
         5.4.1.4.  MAP-E . . . . . . . . . . . . . . . . . . . . . .  18
         5.4.1.5.  MAP-T . . . . . . . . . . . . . . . . . . . . . .  19
       5.4.2.  Support of IPv6 in IPv4-only WAN access . . . . . . .  19
         5.4.2.1.  6in4  . . . . . . . . . . . . . . . . . . . . . .  19
         5.4.2.2.  6rd . . . . . . . . . . . . . . . . . . . . . . .  20
     5.5.  IPv4 Multicast Support  . . . . . . . . . . . . . . . . .  22
     5.6.  Security Considerations . . . . . . . . . . . . . . . . .  22
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  22
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  23
   8.  ANNEX A: Code Considerations  . . . . . . . . . . . . . . . .  23
   9.  ANNEX B: Changes from RFC7084 . . . . . . . . . . . . . . . .  24
   10. ANNEX C: Changes from RFC7084-bis-00  . . . . . . . . . . . .  24
   11. ANNEX D: Changes from RFC7084-bis-01  . . . . . . . . . . . .  25
   12. ANNEX E: Changes from RFC7084-bis-02  . . . . . . . . . . . .  25
   13. ANNEX F: Changes from RFC7084-bis-03  . . . . . . . . . . . .  25
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  26
     14.2.  Informative References . . . . . . . . . . . . . . . . .  31
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  31






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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, at least in the LAN side.

   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
   from the service provider network.  Automatic provisioning of more
   complex topology than a single router with multiple LAN interfaces
   may be handled by means of HNCP ([RFC7788]).  In some cases, manual
   provisioning may be acceptable, when intended for a small number of
   customers.

   This document doesn't cover the specific details of each possible
   access technology.  For example, if the IPv6 CE is supporting built-
   in or external 3GPP/LTE interfaces, [RFC7849] is a relevant
   reference.  See [RFC4779] for a discussion of options available for
   deploying IPv6 in wireline service provider access networks.

   This document also covers the IP transition technologies required in
   a world where IPv4 addresses are no longer available, so the service
   providers need to provision IPv6-only WAN access, while at the same
   time ensuring that IPv4-only or IPv6-only devices or applications in
   the customer LANs can still reach IPv4-only devices or applications
   in Internet, which still don't have IPv6 support.

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 IPv6 CE router that interoperates successfully with a
   particular subset of currently deploying and planned common IPv6
   access networks.






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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.  In other
                             documents, the IPv6 CE is named as CPE
                             (Customer Premises Equipment or Customer
                             Provided Equipment).  In the context of
                             this document, both terminologies are
                             synonymous.

   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.

   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 FTTH,
                             DSL, cable, wireless, 3GPP/LTE, 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.







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3.  Usage Scenarios

   The IPv6 CE router described in this document is expected to be used
   typically, in any of the following scenarios:

   1.  Residential/household users.  Common usage is any kind of
       Internet access (web, email, streaming, online gaming, etc.).

   2.  Residential with Small Office/Home Office (SOHO).  Same usage as
       for the first scenario.

   3.  Small Office/Home Office (SOHO).  Same usage as for the first
       scenario.

   4.  Small and Medium Enterprise (SME).  Same usage as for the first
       scenario.

   5.  Residential/household with advanced requirements.  Same basic
       usage as for the first scenario, however there may be
       requirements for exporting services to the WAN (IP cameras, web,
       DNS, email, VPN, etc.).

   6.  Small and Medium Enterprise (SME) with advanced requirements.
       Same basic usage as for the first scenario, however there may be
       requirements for exporting services to the WAN (IP cameras, web,
       DNS, email, VPN, etc.).

   The above list is not intended to be comprehensive of all the
   possible usage scenarios, just the main ones.  In fact, combinations
   of the above usages are also possible, for example a residential with
   SOHO and advanced requirements.

   The mechanisms for exporting IPv6 services are commonly "naturally"
   available in any IPv6 router, as when using GUA, unless they are
   blocked by firewall rules, which may require some manual
   configuration by means of a GUI and/or CLI.

   However, in the case of IPv4, because the usage of private addresses
   and NAT, it typically requires some degree of manual configuration
   such as setting up a DMZ, virtual servers, or port/protocol
   forwarding.  In general, CE routers already provide GUI and/or CLI to
   manually configure them, or the possibility to setup the CE in bridge
   mode, so another CE behind it, takes care of that.  It is out of the
   scope of this document the definition of any requirements for that.

   The main difference for an IPv6 CE router to support one or several
   of the above indicated scenarios, is related to the packet processing
   capabilities, performance, even other details such as the number of



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   WAN/LAN interfaces, their maximum speed, memory for keeping tables or
   tracking connections, etc.  So, it is out of the scope of this
   document to classify them.

   For example, an SME may have just 10 employees (micro-SME), which
   commonly will be considered same as a SOHO, but a small SME can have
   up to 50 employees, or 250 for a medium one.  Depending on the IPv6
   CE router capabilities or even how it is being configured (for
   instance, using SLAAC or DHCPv6), it may support even a higher number
   of employees if the traffic in the LANs is low, or switched by
   another device(s), or the WAN bandwidth requirements are low, etc.
   The actual bandwidth capabilities of access with technologies such as
   FTTH, cable and even 3GPP/LTE, allows the support of such usages, and
   indeed, is a very common situation that access networks and the IPv6
   CE provided by the service provider are the same for SMEs and
   residential users.

   There is also no difference in terms of who actually provides the
   IPv6 CE router.  In most of the cases is the service provider, and in
   fact is responsible, typically, of provisioning/managing at least the
   WAN side.  However, commonly the user has access to configure the LAN
   interfaces, firewall, DMZ, and many other aspects.  In fact, in many
   cases, the user must supply, or at least can replace the IPv6 CE
   router, which makes even more relevant that all the IPv6 CE routers,
   support the same requirements defined in this document.

   The IPv6 CE router described in this document is not intended for
   usage in other scenarios such as bigger Enterprises, Data Centers,
   Content Providers, etc.  So, even if the documented requirements meet
   their needs, may have additional requirements, which are out of the
   scope of this document.

4.  Architecture

4.1.  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



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   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.

4.2.  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, in the sense that is not
   providing transit to other external networks.  However HNCP
   ([RFC7788]) allows support for automatic provisioning of downstream
   routers.  Figure 1 illustrates the model topology for the end-user
   network.



























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

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

   This architecture describes the:

   o  Basic capabilities of an IPv6 CE router

   o  Provisioning of the WAN interface connecting to the service
      provider

   o  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 or using HNCP ([RFC7788]).
   Automatic provisioning and configuration is described for a single
   IPv6 CE router only.

4.2.1.  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.

5.  Requirements

5.1.  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



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   and does not originate from the WAN interface.

   G-1:  An IPv6 CE router is an IPv6 node according to the IPv6 Node
         Requirements specification [RFC6434].

   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].

   G-6:  The IPv6 CE router MUST comply with [RFC7608].

5.2.  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



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         act as an IPv6 host for the purposes of stateless [RFC4862] or
         stateful [RFC3315] interface address assignment.

   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 ([RFC3633]).

   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 IPv6 CE router SHOULD support a Port
         Control Protocol (PCP) client as specified in [RFC6887] for use
         by applications on the IPv6 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 IPv6 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



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            Autoconfiguration (SLAAC) [RFC4862].

   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 [RFC3315] 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 [RFC3315], 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 IPv6 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 IPv6 CE router MUST support the SOL_MAX_RT option
            [RFC7083] 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
            [RFC4242].

   Prefix delegation requirements:

   WPD-1:  The IPv6 CE router MUST support DHCPv6 prefix delegation
           requesting router behavior as specified in [RFC3633]
           (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
           IPv6 CE router to use DHCPv6 prefix delegation when the IPv6
           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 IPv6 CE router with a destination
           address in the prefix(es) delegated to the IPv6 CE router but
           not in the set of prefixes assigned by the IPv6 CE router to
           the LAN must be dropped.  In other words, the next hop for
           the prefix(es) delegated to the IPv6 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.

   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



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           contain any addresses, unless configured to only obtain its
           WAN IPv6 address via DHCPv6; see [RFC7550].

   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.

5.3.  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.

   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.



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   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 [RFC3315] OR a stateless
          DHCPv6 server according to [RFC3736] 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].

   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 [RFC6106].



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   L-12:  The IPv6 CE router SHOULD implement a DNS proxy as described
          in [RFC5625].

   L-13:  The IPv6 CE router SHOULD make available a subset of DHCPv6
          options (as listed in Section 5.3 of [RFC3736]) received from
          the DHCPv6 client on its WAN interface to its LAN-side DHCPv6
          server.

   L-14:  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-15:  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.

   L-16:  The IPv6 CE router SHOULD provide HNCP (Home Networking
          Control Protocol) services, as specified in [RFC7788].

5.4.  Transition Technologies Support

   Even if the main target of this document is the support of IPv6-only
   WAN access, for some time, there will be a need to support IPv4-only
   devices and applications in the customers LANs, in one side of the
   picture.  In the other side, some Service Providers willing to deploy
   IPv6, may not be able to do so in the first stage, neither as
   IPv6-only or dual-stack in the WAN.  Consequently, transition
   technologies to resolve both issues should be taken in consideration.

5.4.1.  IPv4 Service Continuity in Customer LANs

5.4.1.1.  464XLAT

   464XLAT [RFC6877] is a technique to provide IPv4 access service to
   IPv6-only edge networks without encapsulation.

   The IPv6 CE router SHOULD support CLAT functionality.  If 464XLAT is
   supported, it MUST be implemented according to [RFC6877].  The
   following CE Requirements also apply:

   464XLAT requirements:




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   464XLAT-1:  The IPv6 CE router MUST perform IPv4 Network Address
               Translation (NAT) on IPv4 traffic translated using the
               CLAT, unless a dedicated /64 prefix has been acquired
               using DHCPv6-PD [RFC3633].

   464XLAT-2:  The IPv6 CE router MUST implement [RFC7050] in order to
               discover the PLAT-side translation IPv4 and IPv6
               prefix(es)/suffix(es).  In environments with PCP support,
               the IPv6 CE SHOULD follow [RFC7225] to learn the PLAT-
               side translation IPv4 and IPv6 prefix(es)/suffix(es) used
               by an upstream PCP-controlled NAT64 device.

5.4.1.2.  Dual-Stack Lite (DS-Lite)

   Dual-Stack Lite [RFC6333] enables both continued support for IPv4
   services and incentives for the deployment of IPv6.  It also
   de-couples IPv6 deployment in the service provider network from the
   rest of the Internet, making incremental deployment easier.  Dual-
   Stack Lite enables a broadband service provider to share IPv4
   addresses among customers by combining two well-known technologies:
   IP in IP (IPv4-in-IPv6) and Network Address Translation (NAT).  It is
   expected that DS-Lite traffic is forwarded over the IPv6 CE router's
   native IPv6 WAN interface, and not encapsulated in another tunnel.

   The IPv6 CE router SHOULD implement DS-Lite functionality.  If
   DS-Lite is supported, it MUST be implemented according to [RFC6333].
   This document takes no position on simultaneous operation of Dual-
   Stack Lite and native IPv4.  The following IPv6 CE router
   requirements also apply:

   DS-Lite requirements:

   DSLITE-1:  The IPv6 CE router MUST support configuration of DS-Lite
              via the DS-Lite DHCPv6 option [RFC6334].  The IPv6 CE
              router MAY use other mechanisms to configure DS-Lite
              parameters.  Such mechanisms are outside the scope of this
              document.

   DSLITE-2:  The IPv6 CE router MUST support the DHCPv6 S46 priority
              option described in [RFC8026].

   DSLITE-3:  The IPv6 CE router MUST NOT perform IPv4 Network Address
              Translation (NAT) on IPv4 traffic encapsulated using DS-
              Lite.

   DSLITE-4:  If the IPv6 CE router is configured with an IPv4 address
              on its WAN interface, then the IPv6 CE router SHOULD
              disable the DS-Lite Basic Bridging BroadBand (B4) element.



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5.4.1.3.  Lightweight 4over6 (lw4o6)

   Lw4o6 [RFC7596] specifies an extension to DS-Lite, which moves the
   NAPT function from the DS-Lite tunnel concentrator to the tunnel
   client located in the IPv6 CE router, removing the requirement for a
   CGN function in the tunnel concentrator and reducing the amount of
   centralized state.

   The IPv6 CE router SHOULD implement lw4o6 functionality.  If DS-Lite
   is implemented, lw4o6 MUST be supported as well.  If lw4o6 is
   supported, it MUST be implemented according to [RFC7596].  This
   document takes no position on simultaneous operation of lw4o6 and
   native IPv4.  The following IPv6 CE router Requirements also apply:

   Lw4o6 requirements:

   LW4O6-1:  The IPv6 CE router MUST support configuration of lw4o6 via
             the lw4o6 DHCPv6 options [RFC7598].  The IPv6 CE router MAY
             use other mechanisms to configure lw4o6 parameters.  Such
             mechanisms are outside the scope of this document.

   LW4O6-2:  The IPv6 CE router MUST support the DHCPv6 S46 priority
             option described in [RFC8026].

   LW4O6-3:  The IPv6 CE router MUST support the DHCPv4-over-DHCPv6
             (DHCP 4o6) transport described in [RFC7341].

   LW4O6-4:  The IPv6 CE router MAY support Dynamic Allocation of Shared
             IPv4 Addresses as described in [RFC7618].

5.4.1.4.  MAP-E

   MAP-E [RFC7597] is a mechanism for transporting IPv4 packets across
   an IPv6 network using IP encapsulation, including a generic mechanism
   for mapping between IPv6 addresses and IPv4 addresses as well as
   transport-layer ports.

   The IPv6 CE router SHOULD support MAP-E functionality.  If MAP-E is
   supported, it MUST be implemented according to [RFC7597].  The
   following CE Requirements also apply:

   MAP-E requirements:

   MAPE-1:  The IPv6 CE router MUST support configuration of MAP-E via
            the MAP-E DHCPv6 options [RFC7598].  The IPv6 CE router MAY
            use other mechanisms to configure MAP-E parameters.  Such
            mechanisms are outside the scope of this document.




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   MAPE-2:  The IPv6 CE router MUST support the DHCPv6 S46 priority
            option described in [RFC8026].

5.4.1.5.  MAP-T

   MAP-T [RFC7599] is a mechanism similar to MAP-E, differing from it in
   that MAP-T uses IPv4-IPv6 translation, rather than encapsulation, as
   the form of IPv6 domain transport.

   The IPv6 CE router SHOULD support MAP-T functionality.  If MAP-T is
   supported, it MUST be implemented according to [RFC7599].  The
   following IPv6 CE Requirements also apply:

   MAP-T requirements:

   MAPT-1:  The CE router MUST support configuration of MAP-T via the
            MAP-E DHCPv6 options [RFC7598].  The IPv6 CE router MAY use
            other mechanisms to configure MAP-E parameters.  Such
            mechanisms are outside the scope of this document.

   MAPT-2:  The IPv6 CE router MUST support the DHCPv6 S46 priority
            option described in [RFC8026].

5.4.2.  Support of IPv6 in IPv4-only WAN access

5.4.2.1.  6in4

   6in4 [RFC4213] specifies a tunneling mechanism to allow end-users to
   manually configure IPv6 support via a service provider's IPv4 network
   infrastructure.

   The IPv6 CE router MAY support 6in4 functionality.  6in4 used for a
   manually configured tunnel requires a subset of the 6rd parameters
   (delegated prefix and remote IPv4 end-point).  The on-wire and
   forwarding plane is identical for both mechanisms, however 6in4
   doesn't support mesh traffic and requires manually provisioning.
   Thus, if the device supports either 6rd or 6in4, it's commonly a
   minor UI addition to support both.  If 6in4 is supported, it MUST be
   implemented according to [RFC4213].  The following CE Requirements
   also apply:

   6in4 requirements:

   6IN4-1:  The IPv6 CE router SHOULD support 6in4 automated
            configuration by means of the 6rd DHCPv4 Option 212.  If the
            IPv6 CE router has obtained an IPv4 network address through
            some other means such as PPP, it SHOULD use the DHCPINFORM
            request message [RFC2131] to request the 6rd DHCPv4 Option.



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            The IPv6 CE router MAY use other mechanisms to configure
            6in4 parameters.  Such mechanisms are outside the scope of
            this document.

   6IN4-2:  If the IPv6 CE router is capable of automated configuration
            of IPv4 through IPCP (i.e., over a PPP connection), it MUST
            support user-entered configuration of 6in4.

   6IN4-3:  If the IPv6 CE router supports configuration mechanisms
            other than the 6rd DHCPv4 Option 212 (user-entered, TR-069
            [TR-069], etc.), the IPv6 CE router MUST support 6in4 in
            "hub and spoke" mode. 6in4 in "hub and spoke" requires all
            IPv6 traffic to go to the 6rd Border Relay, which in this
            case is the tunnel-end-point.  In effect, this requirement
            removes the "direct connect to 6rd" route defined in
            Section 7.1.1 of [RFC5969].

   6IN4-4:  The IPv6 CE router MUST allow 6in4 and native IPv6 WAN
            interfaces to be active alone as well as simultaneously in
            order to support coexistence of the two technologies during
            an incremental transition period such as a transition from
            6in4 to native IPv6.

   6IN4-5:  Each packet sent on a 6in4 or native WAN interface MUST be
            directed such that its source IP address is derived from the
            delegated prefix associated with the particular interface
            from which the packet is being sent (Section 4.3 of
            [RFC3704]).

   6IN4-6:  The IPv6 CE router MUST allow different as well as identical
            delegated prefixes to be configured via each (6in4 or
            native) WAN interface.

   6IN4-7:  In the event that forwarding rules produce a tie between
            6in4 and native IPv6, by default, the IPv6 CE router MUST
            prefer native IPv6.

5.4.2.2.  6rd

   6rd [RFC5969] specifies an automatic tunneling mechanism tailored to
   advance deployment of IPv6 to end users via a service provider's IPv4
   network infrastructure.  Key aspects include automatic IPv6 prefix
   delegation to sites, stateless operation, simple provisioning, and
   service that is equivalent to native IPv6 at the sites that are
   served by the mechanism.  It is expected that such traffic is
   forwarded over the IPv6 CE router's native IPv4 WAN interface and not
   encapsulated in another tunnel.




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   The IPv6 CE router MAY support 6rd functionality.  If 6rd is
   supported, it MUST be implemented according to [RFC5969].  The
   following CE Requirements also apply:

   6rd requirements:

   6RD-1:  The IPv6 CE router MUST support 6rd configuration via the 6rd
           DHCPv4 Option 212.  If the IPv6 CE router has obtained an
           IPv4 network address through some other means such as PPP, it
           SHOULD use the DHCPINFORM request message [RFC2131] to
           request the 6rd DHCPv4 Option.  The IPv6 CE router MAY use
           other mechanisms to configure 6rd parameters.  Such
           mechanisms are outside the scope of this document.

   6RD-2:  If the IPv6 CE router is capable of automated configuration
           of IPv4 through IPCP (i.e., over a PPP connection), it MUST
           support user-entered configuration of 6rd.

   6RD-3:  If the IPv6 CE router supports configuration mechanisms other
           than the 6rd DHCPv4 Option 212 (user-entered, TR-069
           [TR-069], etc.), the IPv6 CE router MUST support 6rd in "hub
           and spoke" mode. 6rd in "hub and spoke" requires all IPv6
           traffic to go to the 6rd Border Relay.  In effect, this
           requirement removes the "direct connect to 6rd" route defined
           in Section 7.1.1 of [RFC5969].

   6RD-4:  The IPv6 CE router MUST allow 6rd and native IPv6 WAN
           interfaces to be active alone as well as simultaneously in
           order to support coexistence of the two technologies during
           an incremental transition period such as a transition from
           6rd to native IPv6.

   6RD-5:  Each packet sent on a 6rd or native WAN interface MUST be
           directed such that its source IP address is derived from the
           delegated prefix associated with the particular interface
           from which the packet is being sent (Section 4.3 of
           [RFC3704]).

   6RD-6:  The IPv6 CE router MUST allow different as well as identical
           delegated prefixes to be configured via each (6rd or native)
           WAN interface.

   6RD-7:  In the event that forwarding rules produce a tie between 6rd
           and native IPv6, by default, the IPv6 CE router MUST prefer
           native IPv6.






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5.5.  IPv4 Multicast Support

   Actual deployments support IPv4 multicast for services such as IPTV.
   In the transition phase it is expected that multicast services will
   still be provided using IPv4 to the customer LANs.

   In order to support the delivery of IPv4 multicast services to IPv4
   clients over an IPv6 multicast network, the IPv6 CE router SHOULD
   support [RFC8114] and [RFC8115].

5.6.  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 IPv6 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 SHOULD support ingress filtering in
         accordance with BCP 38 [RFC2827].  Note that this requirement
         was downgraded from a MUST from RFC 6204 due to the difficulty
         of implementation in the IPv6 CE router and the feature's
         redundancy with upstream router ingress filtering.

   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.

6.  Acknowledgements

   Thanks to James Woodyatt, Mohamed Boucadair, Masanobu Kawashima,
   Mikael Abrahamsson, Barbara Stark, Ole Troan and Brian Carpenter for
   their review and comments.

   This document is an update of RFC7084, whose original authors were:
   Hemant Singh, Wes Beebee, Chris Donley and Barbara Stark.  The rest
   of the text on this section and the Contributors section, are the



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   original acknowledgements and Contributors sections of the earlier
   version of this 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.

7.  Contributors

   The following people have participated as co-authors or provided
   substantial contributions to this 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.

8.  ANNEX A: Code Considerations

   One of the apparent main issues for vendors to include new
   functionalities, such as support for new transition mechanisms, is
   the lack of space in the flash (or equivalent) memory.  However, it
   has been confirmed from existing open source implementations
   (OpenWRT/LEDE), that adding the support for the new transitions
   mechanisms, requires around 10-12 Kbytes (because most of the code is
   shared among several transition mechanisms), which typically means
   about 0,15% of the existing code size in popular CEs in the market.

   It is also clear that the new requirements don't have extra cost in



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   terms of RAM memory, neither other hardware requirements such as more
   powerful CPUs.

   The other issue seems to be the cost of developing the code for those
   new functionalities.  However at the time of writing this document,
   it has been confirmed that there are several open source versions of
   the required code for supporting the new transition mechanisms, so
   the development cost is negligent, and only integration and testing
   cost may become a minor issue.

9.  ANNEX B: Changes from RFC7084

   The -bis version of this document has some minor text edits here and
   there.  Significant updates are:

   1.  New section "Usage Scenarios".

   2.  Added support of HNCP ([RFC7788]) in LAN (L-16).

   3.  Added support of 464XLAT ([RFC6877]).

   4.  Added support of lw4o6 ([RFC7596]).

   5.  Added support of MAP-E ([RFC7597]) and MAP-T ([RFC7599]).

   6.  As the main scope of this document is the IPv6-only CE (IPv6-only
       in the WAN link), the support of 6rd ([RFC5969]) has been changed
       to MAY.  6in4 ([RFC4213]) support has been included as well in
       case 6rd is supported, as it doesn't require additional code.

   7.  New section "IPv4 Multicast Support".

   8.  Added support for DNS proxy [RFC5625] as general LAN requirement.

   9.  Split of transition in two sub-sections for the sake of clarity.

10.  ANNEX C: Changes from RFC7084-bis-00

   Section to be removed for WGLC.  Significant updates are:

   1.  LW4O6-5 changed to port-restricted to conform with [RFC7596].

   2.  MAPE-3 changed to port-restricted to conform with [RFC7597].

   3.  MAPT-3 changed to port-restricted to conform with [RFC7599].

   4.  [RFC7341] removed from 464XLAT, DS-LITE, MAP-E and MAP-T
       requirements.



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   5.  [RFC5625] removed from 464XLAT, and included as general LAN
       requirement.

   6.  [RFC7618] included as MAY for lw4o6.

   7.  6in4 text clarifications.

   8.  Included non-normative reference to [RFC7849] to clarify that the
       details of the connectivity to 3GPP/LTE networks is out of the
       scope.

   9.  Split of transition in two sub-sections for the sake of clarity.

11.  ANNEX D: Changes from RFC7084-bis-01

   Section to be removed for WGLC.  Significant updates are:

   1.  G-6 added in order to comply with [RFC7608].

   2.  LW4O6-5 removed.

   3.  MAPE-3 removed.

   4.  MAPT-3 removed.

   5.  Included non-normative reference to [RFC7849] to clarify that the
       details of the connectivity to 3GPP/LTE networks is out of the
       scope.

   6.  Split of transition in two sub-sections for the sake of clarity.

12.  ANNEX E: Changes from RFC7084-bis-02

   Section to be removed for WGLC.  Significant updates are:

   1.  LW4O6-5 removed, was a mistake due to copy-paste from DS-LITE.

   2.  Removed citation to individual I-Ds for DHCPv6 options.

13.  ANNEX F: Changes from RFC7084-bis-03

   Section to be removed for WGLC.  Significant updates are:

   1.  Clarifications on text regarding downstream routers support.







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14.  References

14.1.  Normative References

   [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
              Communication Layers", STD 3, RFC 1122,
              DOI 10.17487/RFC1122, October 1989,
              <http://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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, DOI 10.17487/RFC2131, March 1997,
              <http://www.rfc-editor.org/info/rfc2131>.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
              <http://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, <http://www.rfc-editor.org/info/rfc2827>.

   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
              C., and M. Carney, "Dynamic Host Configuration Protocol
              for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
              2003, <http://www.rfc-editor.org/info/rfc3315>.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              DOI 10.17487/RFC3633, December 2003,
              <http://www.rfc-editor.org/info/rfc3633>.

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

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March
              2004, <http://www.rfc-editor.org/info/rfc3704>.






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   [RFC3736]  Droms, R., "Stateless Dynamic Host Configuration Protocol
              (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736,
              April 2004, <http://www.rfc-editor.org/info/rfc3736>.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
              November 2005, <http://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,
              <http://www.rfc-editor.org/info/rfc4193>.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213,
              DOI 10.17487/RFC4213, October 2005,
              <http://www.rfc-editor.org/info/rfc4213>.

   [RFC4242]  Venaas, S., Chown, T., and B. Volz, "Information Refresh
              Time Option for Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 4242, DOI 10.17487/RFC4242, November
              2005, <http://www.rfc-editor.org/info/rfc4242>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", RFC 4443,
              DOI 10.17487/RFC4443, March 2006,
              <http://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, <http://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, <http://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, <http://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,
              <http://www.rfc-editor.org/info/rfc4861>.



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   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <http://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,
              <http://www.rfc-editor.org/info/rfc5072>.

   [RFC5625]  Bellis, R., "DNS Proxy Implementation Guidelines",
              BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009,
              <http://www.rfc-editor.org/info/rfc5625>.

   [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,
              <http://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, <http://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,
              <http://www.rfc-editor.org/info/rfc5942>.

   [RFC5969]  Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
              Infrastructures (6rd) -- Protocol Specification",
              RFC 5969, DOI 10.17487/RFC5969, August 2010,
              <http://www.rfc-editor.org/info/rfc5969>.

   [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,
              <http://www.rfc-editor.org/info/rfc6092>.

   [RFC6106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 6106, DOI 10.17487/RFC6106, November 2010,
              <http://www.rfc-editor.org/info/rfc6106>.

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




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   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
              <http://www.rfc-editor.org/info/rfc6333>.

   [RFC6334]  Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
              Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
              RFC 6334, DOI 10.17487/RFC6334, August 2011,
              <http://www.rfc-editor.org/info/rfc6334>.

   [RFC6434]  Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
              Requirements", RFC 6434, DOI 10.17487/RFC6434, December
              2011, <http://www.rfc-editor.org/info/rfc6434>.

   [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,
              <http://www.rfc-editor.org/info/rfc6603>.

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

   [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,
              <http://www.rfc-editor.org/info/rfc6887>.

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

   [RFC7083]  Droms, R., "Modification to Default Values of SOL_MAX_RT
              and INF_MAX_RT", RFC 7083, DOI 10.17487/RFC7083, November
              2013, <http://www.rfc-editor.org/info/rfc7083>.

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

   [RFC7341]  Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I.
              Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport",
              RFC 7341, DOI 10.17487/RFC7341, August 2014,
              <http://www.rfc-editor.org/info/rfc7341>.




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   [RFC7596]  Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
              Farrer, "Lightweight 4over6: An Extension to the Dual-
              Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
              July 2015, <http://www.rfc-editor.org/info/rfc7596>.

   [RFC7597]  Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S.,
              Murakami, T., and T. Taylor, Ed., "Mapping of Address and
              Port with Encapsulation (MAP-E)", RFC 7597,
              DOI 10.17487/RFC7597, July 2015,
              <http://www.rfc-editor.org/info/rfc7597>.

   [RFC7598]  Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec,
              W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for
              Configuration of Softwire Address and Port-Mapped
              Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015,
              <http://www.rfc-editor.org/info/rfc7598>.

   [RFC7599]  Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,
              and T. Murakami, "Mapping of Address and Port using
              Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July
              2015, <http://www.rfc-editor.org/info/rfc7599>.

   [RFC7608]  Boucadair, M., Petrescu, A., and F. Baker, "IPv6 Prefix
              Length Recommendation for Forwarding", BCP 198, RFC 7608,
              DOI 10.17487/RFC7608, July 2015,
              <http://www.rfc-editor.org/info/rfc7608>.

   [RFC7618]  Cui, Y., Sun, Q., Farrer, I., Lee, Y., Sun, Q., and M.
              Boucadair, "Dynamic Allocation of Shared IPv4 Addresses",
              RFC 7618, DOI 10.17487/RFC7618, August 2015,
              <http://www.rfc-editor.org/info/rfc7618>.

   [RFC7788]  Stenberg, M., Barth, S., and P. Pfister, "Home Networking
              Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
              2016, <http://www.rfc-editor.org/info/rfc7788>.

   [RFC8026]  Boucadair, M. and I. Farrer, "Unified IPv4-in-IPv6
              Softwire Customer Premises Equipment (CPE): A DHCPv6-Based
              Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026,
              November 2016, <http://www.rfc-editor.org/info/rfc8026>.

   [RFC8114]  Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., and Q.
              Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
              over an IPv6 Multicast Network", RFC 8114,
              DOI 10.17487/RFC8114, March 2017,
              <http://www.rfc-editor.org/info/rfc8114>.





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   [RFC8115]  Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
              Option for IPv4-Embedded Multicast and Unicast IPv6
              Prefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017,
              <http://www.rfc-editor.org/info/rfc8115>.

14.2.  Informative References

   [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,
              <http://www.rfc-editor.org/info/rfc7157>.

   [RFC7550]  Troan, O., Volz, B., and M. Siodelski, "Issues and
              Recommendations with Multiple Stateful DHCPv6 Options",
              RFC 7550, DOI 10.17487/RFC7550, May 2015,
              <http://www.rfc-editor.org/info/rfc7550>.

   [RFC7849]  Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley,
              N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner,
              "An IPv6 Profile for 3GPP Mobile Devices", RFC 7849,
              DOI 10.17487/RFC7849, May 2016,
              <http://www.rfc-editor.org/info/rfc7849>.

   [TR-069]   Broadband Forum, "CPE WAN Management Protocol", TR-069
              Amendment 4, July 2011,
              <http://www.broadband-forum.org/technical/trlist.php>.

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

Author's Address

   Jordi Palet Martinez
   Consulintel, S.L.
   Molino de la Navata, 75
   La Navata - Galapagar, Madrid  28420
   Spain

   EMail: jordi.palet@consulintel.es
   URI:   http://www.consulintel.es/









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