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Versions: 00

IPv6 Operations (v6ops)                                J. Palet Martinez
Internet-Draft                                         Consulintel, S.L.
Obsoletes: 7084 (if approved)                              June 10, 2017
Intended status: Informational
Expires: December 12, 2017


        Minimum Requirements for IPv6-only Customer Edge Routers
                   draft-palet-v6ops-rfc7084-bis2-00

Abstract

   This document specifies minimum requirements for an IPv6-only
   Customer Edge (CE) router.  Specifically, the current version of this
   document focuses on the basic provisioning of an IPv6-only CE router
   and the provisioning of IPv6 hosts attached to it.  Neither the
   provisioning of IPv4 nor downstream routers are in the scope of this
   document.  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 12, 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
   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



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified 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  . . . . . . . . . . .   4
       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.  ANNEX A: Changes from RFC7084 . . . . . . . . . . . . . . . .  14
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   This document defines minimum IPv6 features for a very basic
   residential or small- office router, referred to as an "IPv6-only CE
   router", in order to establish an industry baseline for features to
   be implemented on such a router.  This is, as well, the router to be
   used in remote locations where IPv6-only LANs/devices are used to
   connect sensors, displays, etc.

   These routers don't support IPv4, neither functionalities for
   provisioning downstream routers.

   This document specifies how an IPv6-only 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 is
   out of scope for this document.

   This document doesn't cover the specific details of each possible
   access technology.  For example, if the 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



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   wireline service provider access networks.

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-only
                             CE router that connect IPv6 hosts.

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

   LAN Interface             an IPv6-only 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-only 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-only, and it may also



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                             offer IPv4 Internet access, but non
                             intended to be supported by this IPv6-only
                             CE router.  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-only 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.

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, however very simple networks
   may work perfectly with IPv6-only.  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.

3.2.  IPv6 End-User Network Architecture

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



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   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:

   o  Basic capabilities of an IPv6-only 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-only CE router may act as a
   Multicast Listener Discovery (MLD) proxy [RFC4605] and may support a
   dynamic multicast routing protocol.

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








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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-only 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-only 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-only 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-only 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.

4.  Requirements

4.1.  General Requirements

   The IPv6-only CE router is responsible for implementing IPv6 routing;
   that is, the IPv6-only 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-only 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.

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

   G-2:  The IPv6-only 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].




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   G-3:  The IPv6-only 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-only 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-only 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-only CE router MUST comply with [RFC7608].

4.2.  WAN-Side Configuration

   The IPv6-only CE router will need to support connectivity to one or
   more access network architectures.  This document describes an
   IPv6-only 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 IPv6-only CE router is attached to the WAN interface
         link, it MUST act as an IPv6 host for the purposes of stateless
         [RFC4862] or stateful [RFC3315] interface address assignment.

   W-2:  The IPv6-only 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.



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   W-3:  Absent other routing information, the IPv6-only 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 IPv6-only CE router MUST act as a requesting router for the
         purposes of DHCPv6 prefix delegation ([RFC3633]).

   W-5:  The IPv6-only 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-only 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-only CE router MUST support IPv6 over Ethernet
           [RFC2464].

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

   Address assignment requirements:

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

   WAA-2:   The IPv6-only 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-only CE router MUST support DHCPv6 [RFC3315] client
            behavior.

   WAA-4:   The IPv6-only CE router MUST be able to support the
            following DHCPv6 options: Identity Association for Non-
            temporary Address (IA_NA), Reconfigure Accept [RFC3315], and



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            DNS_SERVERS [RFC3646].  The IPv6-only CE router SHOULD be
            able to support the DNS Search List (DNSSL) option as
            specified in [RFC3646].

   WAA-5:   The IPv6-only 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-only 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-only 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-only 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-only 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-only 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.

   WAA-10:  The IPv6-only CE router SHOULD implement the Information
            Refresh Time option and associated client behavior as
            specified in [RFC4242].

   Prefix delegation requirements:

   WPD-1:  The IPv6-only 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-only CE router MAY indicate as a hint to the
           delegating router the size of the prefix it requires.  If so,



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           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-only 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-only 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-only 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-only 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 IPv6-only 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-only 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-only 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 [RFC7550].

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

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







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4.3.  LAN-Side Configuration

   The IPv6-only 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-only 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-only 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-only CE router's LAN interfaces only.

   ULA requirements:

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

   ULA-2:  An IPv6-only 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-only 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-only 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-only CE router MUST support router behavior according



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          to Neighbor Discovery for IPv6 [RFC4861].

   L-2:   The IPv6-only 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-only 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-only 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-only 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-only 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-only 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-only CE router MUST support providing DNS information
          in the DHCPv6 DNS_SERVERS and DOMAIN_LIST options [RFC3646].

   L-11:  The IPv6-only 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].

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

   L-13:  The IPv6-only CE router SHOULD make available a subset of



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          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-only 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-only 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-only CE router ought to support basic stateless egress and
   ingress filters.  The IPv6-only 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-only CE router SHOULD support [RFC6092].  In
         particular, the IPv6-only 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-only 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 CE router and the feature's redundancy
         with upstream router ingress filtering.

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





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5.  Acknowledgements

   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
   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.

6.  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.

7.  ANNEX A: Changes from RFC7084

   The -bis2 version of this document has some minor text edits here and
   there.  Significant updates are:

   1.  Removed, in general requirements related to IPv4/dual-stack
       support.



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   2.  References to IPv6 CE router changed to IPv6-only CE router.

   3.  Removed WLL-3, as it was referring to dual-stack support.

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

   5.  L-12 added to support for DNS proxy [RFC5625] as general LAN
       requirement.

   6.  Removed transition support.

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,
              <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>.

   [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>.



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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>.

   [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>.

   [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>.



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   [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>.

   [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>.

   [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>.





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   [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>.

   [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>.

   [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>.

8.2.  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









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   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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