Network Working Group                                          C. Donley
Internet-Draft                                              D. Kharbanda
Intended status: Informational                                 CableLabs
Expires: January 3, 2010                                   J. Brzozowski
                                                                  Y. Lee
                                                           Comcast Cable
                                                                 J. Weil
                                                      Cox Communications
                                                             K. Erichsen
                                                               L. Howard
                                                       Time Warner Cable
                                                            JF. Tremblay
                                                               Videotron
                                                            July 2, 2009


           Use Cases and Requirements for an IPv6 CPE Router
            draft-donley-ipv6-cpe-rtr-use-cases-and-reqs-00

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on January 3, 2010.

Copyright Notice

   Copyright (c) 2009 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



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   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.















































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Abstract

   This document captures use cases and associated requirements for an
   IPv6 Customer Premises Equipment (CPE) router.  Specifically, the
   current version of this document focuses on the provisioning of an
   IPv6 CPE router and the provisioning of IPv6 Home Devices attached to
   it.  It also addresses IPv6 traffic forwarding and IPv6 CPE Router
   security.  This document also identifies areas for future
   consideration.  These areas include prefix sub-delegation, IPv6
   multicast, transition and tunneling mechanisms, provisioning
   consistency between DHCPv4 and DHCPv6, and DNS support.  This
   document does not address IPv4 use cases or requirements, as they are
   widely understood; however, it is expected that IPv6 CPE Routers will
   also support IPv4.





































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Conventions used in this document  . . . . . . . . . . . . . .  6
     2.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Architecture and Operations  . . . . . . . . . . . . . . . . .  7
     3.1.  Example Network Topology . . . . . . . . . . . . . . . . .  8
   4.  Use Cases and Requirements . . . . . . . . . . . . . . . . . .  9
     4.1.  Service Provider IPv6 Provisioning of the CPE Router . . .  9
       4.1.1.  Description  . . . . . . . . . . . . . . . . . . . . .  9
       4.1.2.  Requirements . . . . . . . . . . . . . . . . . . . . .  9
     4.2.  Provisioning Home Networks and Attached IPv6 Home
           Devices  . . . . . . . . . . . . . . . . . . . . . . . . . 10
       4.2.1.  Description  . . . . . . . . . . . . . . . . . . . . . 10
       4.2.2.  Requirements . . . . . . . . . . . . . . . . . . . . . 11
     4.3.  IPv6 Traffic Forwarding  . . . . . . . . . . . . . . . . . 11
       4.3.1.  Description  . . . . . . . . . . . . . . . . . . . . . 11
       4.3.2.  Requirements . . . . . . . . . . . . . . . . . . . . . 12
     4.4.  CPE Router Security  . . . . . . . . . . . . . . . . . . . 12
       4.4.1.  Description  . . . . . . . . . . . . . . . . . . . . . 12
       4.4.2.  Requirements . . . . . . . . . . . . . . . . . . . . . 12
   5.  Summary of Requirements  . . . . . . . . . . . . . . . . . . . 13
   6.  Optional Use Cases and Requirements  . . . . . . . . . . . . . 16
     6.1.  IPv6 Provisioning of IPv6 Home Devices using Stateful
           DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 16
       6.1.1.  Description  . . . . . . . . . . . . . . . . . . . . . 16
       6.1.2.  Requirements . . . . . . . . . . . . . . . . . . . . . 16
   7.  Future Considerations  . . . . . . . . . . . . . . . . . . . . 17
     7.1.  IPv6 Prefix Sub-delegation . . . . . . . . . . . . . . . . 17
     7.2.  Provide IPv6 Multicast . . . . . . . . . . . . . . . . . . 17
     7.3.  Transition and Tunneling Mechanisms  . . . . . . . . . . . 17
     7.4.  Provisioning Consistency Between DHCPv4 and DHCPv6 . . . . 17
     7.5.  Offer Domain Name Service through an IPv6 CPE Router . . . 17
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
     11.2. Informative References . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23











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1.  Introduction

   This document enumerates common use cases and requirements for IPv6
   CPE Routers.  These requirements should be applicable to a wide
   variety of service provider access networks, including DSL, cable,
   wireless, fiber-based and other services.  This document defines the
   base level of functionality necessary to provide connectivity to the
   end-user's network.  Vendors and other interested parties are
   encouraged to incorporate additional functionality into the feature
   set, as deemed necessary or appropriate.









































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2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 Error!
   Reference source not found..

2.1.  Terminology

      Customer - An end user that receives Internet service from the
      Service Provider.

      Customer Network - one or more subnets attached to the CPE Router
      that connect customer IPv6 Home Devices.

      IPv6 CPE Router - A standalone or embedded IPv6 Internet gateway,
      intended for home or small office use, that routes IPv6 (and
      optionally IPv4) traffic from one or more LAN Interfaces to the
      Internet.

      IPv6 Home Device - a host device such as a personal computer that
      supports IPv6, is located in the home or small office, and
      receives IPv6 Internet connectivity through the IPv6 CPE Router

      LAN Interface - a layer 3 network interface on a link in the
      customer network.  A LAN Interface could attach to Ethernet, IEEE
      802.11, MoCA 1.0/1.1, and other networks.  An IPv6 CPE Router may
      have one or more layer 3 LAN Interfaces

      Service Provider - A company that offers its customers access to
      the Internet.  In this document, a Service Provider specifically
      offers Internet access using IPv6, and may also offer IPv4
      Internet access.  The Service Provider can provide such access
      over a variety of different transport methods such as DSL, cable,
      wireless, and others.

      WAN Interface - the single physical network interface on the
      standalone CPE Router that is used to connect the router to the
      access network of the Service Provider.  When the CPE Router is
      embedded in a bridging device that connects to the WAN (e.g. a
      cable or DSL modem), the CPE Router WAN interface is a logical
      network interface.









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3.  Architecture and Operations

   An IPv6 CPE Router is a consumer oriented routing device, typically
   deployed in a home or small office, for the purpose of forwarding
   layer 3 traffic to IPv6 Home Devices.  The IPv6 CPE Router is
   commonly used as a single point of attachment to a Service Provider
   network.  This document describes a router which primarily operates
   as the core of the end-user's network.  It may support more than one
   subnet.  This IPv6 CPE Router is primarily managed by the end-user
   and provides configuration management and/or monitoring features that
   are outside of the scope of this document.

   The CPE Router is provisioned with a Globally-Unique IPv6 Address
   (GUA) on its WAN interface by the Service Provider.  Service
   providers may use different provisioning modes such as stateful
   DHCPv6, PPPoE, and others; this document focuses on stateful DHCPv6
   because the use case is well-defined and because some Service
   Providers are already implementing DHCPv6 provisioning.  Also,
   stateful DHCPv6 is required for prefix delegation.

   When offering stateful DHCPv6, the Service Provider may use multiple
   DHCPv6 servers to provide redundancy.  In addition to an IA_NA, the
   CPE Router requests prefix delegation.  It also requests
   configuration information for IPv6 Home Devices through the Container
   Option for Server Configuration [I-D.ietf-dhc-container-opt" /> or
   DNS Recursive Name Server, [RFC3646].

   The CPE Router assigns at least a /64 from its delegated prefix to
   each LAN interface.  It may optionally also assign a Unique Local
   Address (ULA) to its LAN Interfaces for communication on the customer
   network; however, the use of ULAs is beyond the scope of this
   document.  To support customer privacy, the CPE Router may have more
   than one LAN interface.

   IPv6 Home Devices acquire IPv6 addresses either through stateless
   address autoconfiguration (SLAAC) or stateful DHCPv6.  It is
   RECOMMENDED that devices use SLAAC to acquire a GUA.  The CPE Router
   provides configuration information obtained from the Service Provider
   to the Home Device either through stateless DHCP or the [RFC5006]
   Recursive DNS Server (RDNSS) option.  In some cases, stateful DHCP
   may optionally be used.  Stateful DHCPv6 may be advantageous to
   support a CPE Router with a public wireless access point, where a
   Service Provider needs to maintain a mapping between a customer
   device and a GUA as required by law.

   The IPv6 CPE Router is responsible for implementing IPv6 routing;
   that is, the CPE Router must look up the IPv6 Destination address in
   its routing table to decide to which interface it should send the



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   packet.

   The CPE Router should use basic ingress and egress traffic filters to
   filter "martian" or obviously spoofed traffic.  It should also allow
   customer-configurable packet filters.

3.1.  Example Network Topology

   The following figure illustrates how an IPv6 CPE Router may be
   deployed in a basic customer network.  Many of the use cases will
   refer to this figure.


                       +-------+-------+                   \
                      |   Service     |                    \
                      |   Provider    |                     | ISP
                      |    Router     |                     | network
                      +-------+-------+                     |
                              |                             /
                              | Subscriber                 /
                              | Internet connection       /
                              |
                       +------+------+                    \
                       |     IPv6    |                     \
                       |     CPE     |                      \
                       |    Router   |                      /
                       +---+-------+-+                     /
        Home Network 1     |       |  Home Network 2      | Customer
     ---+-------------+----+-    --+--+-------------+---  | network(s)
        |             |               |             |      \
   +----+-----+ +-----+----+     +----+-----+ +-----+----+  \
   |IPv6 Home | |IPv6 Home |     | IPv6 Home| |IPv6 Home |  /
   |   Device | |  Device  |     |   Device | | Device   | /
   +----------+ +-----+----+     +----------+ +----------+/


   An example of a CPE Router deployment.














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4.  Use Cases and Requirements

   This section presents the use cases and associated requirements for
   an IPv6 CPE Router.

4.1.  Service Provider IPv6 Provisioning of the CPE Router

4.1.1.  Description

   The IPv6 CPE Router acquires a GUA for its WAN interface, and obtains
   other configuration parameters, as needed.

   Service Providers may use different provisioning methods depending on
   the characteristics of the transport method (e.g. cable, DSL,
   wireless, fiber, etc.) and the Service Provider's provisioning
   environment.

   It is RECOMMENDED that the CPE Router to use DHCPv6 to obtain an IPv6
   GUA.  The CPE Router is required to use DHCPv6 on its WAN interface
   to obtain a delegated prefix for the customer network on its LAN
   interfaces.  When DHCPv6 is required, the CPE Router is not expected
   to acquire connectivity information through stateless address
   autoconfiguration (SLAAC) or stateless DHCPv6.

4.1.2.  Requirements

4.1.2.1.  Obtain Link-Local Address

   The CPE Router follows [RFC4862] to obtain a link-local address, join
   the all-nodes multicast address, and perform Duplicate Address
   Detection (DAD) on all LAN and WAN interfaces.  If the CPE Router
   determines that the constructed link-local address is already in use,
   the CPE Router SHOULD terminate IPv6 operation on that interface.

4.1.2.2.  Perform router discovery

   The CPE Router follows [RFC4861] to perform router discovery on its
   WAN interface.

4.1.2.3.  Obtain IPv6 Address and Other Configuration Parameters

   The CPE Router MUST follow the M and O bits in the RA to assign an
   IPv6 address to the WAN interface; the prefix advertisement options
   and associated L bits to identify "on-link" prefixes; and associated
   A bits to assign a SLAAC address.  It is RECOMMENDED that the RA
   received by the CPE Router have its M bit set to 1.  Under this
   recommendation, the CPE Router uses DHCPv6 as described in [RFC3315]
   to obtain its IPv6 address and default route for its WAN Interface



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   and other configuration information (and ignore the O bit).  The CPE
   Router MUST use the DHCPv6 [RFC3633] IA_PD option to obtain a
   delegated prefix for the customer network.

   Because many Internet access topologies for home users require that
   traffic be sent to the Service Provider's router, if the prefix
   advertisement has the L bit set to 0, the CPE Router SHOULD identify
   the prefix as "not-on-link" and forward traffic destined for that
   prefix to the router.

   The CPE Router SHOULD request values for the following options
   through DHCP: Client Identifier, IA_NA, IA_PD, Reconfigure Accept,
   and Options Request Option for the DNS Recursive Name Server,
   [RFC3646] and the Container Option for Server Configuration
   [I-D.ietf-dhc-container-opt].  The CPE Router MAY also accept and
   request additional information via DHCP.

   To facilitate DHCP reconfiguration in response to changes in the
   Service Provider network, the CPE Router SHOULD support the
   Reconfigure Key Authentication Protocol, as described in [RFC3315].

   In order to protect against malicious traffic, the CPE Router MUST
   NOT forward any IPv6 traffic between its LAN Interface(s) and its WAN
   Interface until the router has successfully completed the IPv6
   provisioning process.  Even if the WAN interface does not have an
   IPv6 GUA, the CPE Router MAY forward IPv6 traffic between its LAN
   interfaces.  The CPE Router SHOULD forward IPv6 traffic between its
   LAN interfaces if it has received a delegated prefix.

4.2.  Provisioning Home Networks and Attached IPv6 Home Devices

4.2.1.  Description

   The CPE Router distributes configuration information obtained during
   WAN interface provisioning to IPv6 Home Devices and assists IPv6 Home
   Devices in obtaining an IPv6 GUA.

   IPv6 Home Devices can acquire an IPv6 GUA statelessly using SLAAC or
   statefully using DHCPv6.  If SLAAC is used, additional configuration
   parameters beyond the GUA, such as DNS server address, could be
   passed to the Home Device using stateless DHCPv6 or RDNSS.

   It is RECOMMENDED that an IPv6 Home Device acquires an IPv6 GUA using
   SLAAC and additional information using stateless DHCPv6.







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4.2.2.  Requirements

4.2.2.1.  Assigning IPv6 Addresses to CPE Router LAN Interfaces

   The CPE Router SHOULD minimally assign a unique /64 from its received
   IA_PD to each of its LAN interfaces.

4.2.2.2.  Assigning IPv6 Addresses using SLAAC

   The CPE router acts as a router through each of its LAN interfaces as
   described in [RFC4861].  Unless the CPE Router is otherwise
   configured by an administrator, the RA SHOULD set:

   o  the M bit to 0

   o  the O bit to 1

   o  a prefix advertisement for the /64 applied to the LAN interface
      with the A bit set to 1 and the L bit set to 1

4.2.2.3.  IPv6 Provisioning using Stateless DHCPv6

   On the LAN Interface, the Home Device may request additional
   provisioning options such as a DNS server address through stateless
   DHCPv6, as described in [RFC3315] and [RFC3736].

   The CPE Router SHOULD serve as a stateless DHCPv6 server.  The CPE
   Router SHOULD pass the additional set of DHCPv6 options received from
   the DHCP client on its WAN interface from the Service Provider to
   IPv6 Home Devices.  Information received in a Container Option by the
   DHCP client overrides other information received by the client.  The
   CPE router need not serve as a DHCPv6 Relay Agent.

4.2.2.4.  IPv6 Provisioning using RFC 5006

   IPv6 CPE Router Router Advertisements MAY include the RDNSS option as
   specified in [RFC5006].  In that case, the IPv6 CPE Router MUST set
   the O bit of the RA message to 0.  The IPv6 CPE Router SHOULD include
   information received in the DHCP Container Option for Server
   Configuration, if sent by the Service Provider during CPE Router WAN
   Interface provisioning.

4.3.  IPv6 Traffic Forwarding

4.3.1.  Description

   The IPv6 CPE Router is responsible for implementing IPv6 routing;
   that is, the CPE Router must look up the IPv6 Destination address in



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   its routing table to decide to which interface it should send the
   packet.  The typical scenario for packets routed to the WAN Interface
   is that the next-hop router will be the CPE Router's default route,
   learned via Router Advertisement from the Service Provider router.

4.3.2.  Requirements

   The CPE Router MUST support the Neighbor Discovery (ND) protocol, as
   described in [RFC4861], on each of its LAN and WAN interfaces.

   The CPE Router also discovers other devices on the network connected
   to the WAN interface using ND.  Consistent with [RFC4943], unless the
   L bit in the RA is set to 1, the CPE Router SHOULD assume that such
   devices are "not-on-link", so traffic for such devices SHOULD be
   forwarded to the default router.

4.4.  CPE Router Security

4.4.1.  Description

   It is considered a best practice to filter obviously malicious
   traffic (e.g. spoofed packets, "martian" addresses, etc.).  Thus, the
   IPv6 CPE Router should support basic stateless egress and ingress
   filters.  The CPE router should also 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.

4.4.2.  Requirements

   The CPE Router SHOULD support [I-D.ietf-v6ops-cpe-simple-security].

   The CPE Router MUST support ingress filtering in accordance with
   [RFC2827] (BCP 38).

















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5.  Summary of Requirements

      GEN-REQ1: The CPE Router SHOULD support the following RFCs:

      *  [RFC2710] Multicast Listener Discovery (MLD) for IPv6

      *  [RFC3315] Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

      *  [RFC3633] IPv6 Prefix Options for Dynamic Host Configuration
         Protocol (DHCP) version 6

      *  [RFC3646] DNS Configuration options for Dynamic Host
         Configuration Protocol for IPv6 (DHCPv6)

      *  [RFC4075] Simple Network Time Protocol (SNTP) Configuration
         Option for DHCPv6.

      *  [RFC4242] Information Refresh Time Option for Dynamic Host
         Configuration Protocol for IPv6 (DHCPv6).

      *  [RFC4291] IP Version 6 Addressing Architecture

      *  [RFC4861] Neighbor Discovery for IP version 6 (IPv6)

      *  [RFC4862] IPv6 Stateless Address Autoconfiguration

      CRP-REQ1: If the CPE Router determines that the constructed link-
      local address is already in use, the CPE Router SHOULD terminate
      IPv6 operation on that interface.

      CRP-REQ2: The CPE Router MUST follow the M and O bits in the RA to
      assign an IPv6 address to the WAN interface; the prefix
      advertisement options and associated L bits to identify "on-link"
      prefixes; and associated A bits to assign a SLAAC address.

      CRP-REQ3: The CPE Router MUST use the DHCPv6 [RFC3633] IA_PD
      option to obtain a delegated prefix for the customer network.

      CRP-REQ4: The CPE Router SHOULD request values for the following
      options through DHCP: Client Identifier, IA_NA, IA_PD, Reconfigure
      Accept, and Options Request Option for the DNS Recursive Name
      Server, [RFC3646] and the Container Option for Server
      Configuration [I-D.ietf-dhc-container-opt].

      CRP-REQ5: The CPE Router MAY also accept and request additional
      information via DHCP.





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      CRP-REQ6: To facilitate DHCP reconfiguration in response to
      changes in the Service Provider network, the CPE Router SHOULD
      support the Reconfigure Key Authentication Protocol, as described
      in [RFC3315]

      CRP-REQ7: In order to protect against malicious traffic, the CPE
      Router MUST NOT forward any IPv6 traffic between its LAN
      Interface(s) and its WAN Interface until the router has
      successfully completed the IPv6 provisioning process.

      CRP-REQ8: Even if the WAN interface does not have an IPv6 GUA, the
      CPE Router SHOULD forward IPv6 traffic between its LAN interfaces.

      CRP-REQ9: The CPE Router SHOULD forward IPv6 traffic between its
      LAN interfaces if it has received a delegated prefix.

      SHP-REQ1: The CPE Router SHOULD minimally assign a unique /64 from
      its received IA_PD to each of its LAN interfaces.

      SHP-REQ2: Unless the CPE Router is otherwise configured by an
      administrator, the RA SHOULD set:

      *  the M bit to 0

      *  the O bit to 1

      *  a prefix advertisement for the /64 applied to the LAN interface
         with the A bit set to 1 and the L bit set to 1

      SHP-REQ3: The CPE Router SHOULD serve as a stateless DHCPv6
      server.

      SHP-REQ4: The CPE Router SHOULD pass the additional set of DHCPv6
      options received from the DHCP client on its WAN interface from
      the Service Provider to IPv6 Home Devices.

      SHP-REQ5: IPv6 CPE Router Router Advertisements MAY include the
      RDNSS option as specified in [RFC5006].  In that case, the IPv6
      CPE Router MUST set the O bit of the RA message to 0.

      SHP-REQ6: The IPv6 CPE Router SHOULD include information received
      in the DHCP Container Option for Server Configuration, if sent by
      the Service Provider during CPE Router WAN Interface
      provisioning..







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      TF-REQ1: The CPE Router MUST support the Neighbor Discovery (ND)
      protocol, as described in [RFC4861], on each of its LAN and WAN
      interfaces.

      TF-REQ2: Consistent with [RFC4943], unless the L bit in the RA is
      set to 1, the CPE Router SHOULD assume that such devices are "not-
      on-link", so traffic for such devices SHOULD be forwarded to the
      default router.

      S-REQ1: The CPE Router SHOULD support
      [I-D.ietf-v6ops-cpe-simple-security].

      S-REQ2: The CPE Router MUST support ingress filtering in
      accordance with The CPE Router MUST support ingress filtering in
      accordance with [RFC2827](BCP 38)




































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6.  Optional Use Cases and Requirements

6.1.  IPv6 Provisioning of IPv6 Home Devices using Stateful DHCPv6

6.1.1.  Description

   The default provisioning mode for IPv6 Home Devices is to use SLAAC;
   however, in some cases, stateful provisioning may be required.  In
   such cases, the CPE Router could also support stateful DHCPv6.  It is
   preferable for the Service Provider to delegate a prefix to the CPE
   Router, rather than have the CPE Router relay DHCP messages to the
   Service Provider's provisioning infrastructure.

6.1.2.  Requirements

   The CPE Router MAY serve as a stateful DHCPv6 server.  When
   configured to enable stateful DHCPv6, the CPE Router SHOULD generate
   Router Advertisements (RA) on its LAN Interfaces as per [RFC4862],
   setting the M bit to indicate DHCP.

   Per [RFC3315], the CPE Router SHOULD assign an IA_NA and pass values
   for the additional set of DHCPv6 options received from the Service
   Provider through the [I-D.ietf-dhc-container-opt]Container Option or
   the DNS Recursive Name Server option as specified in [RFC3646], and
   may send values for additional options.  The CPE router need not
   serve as a DHCPv6 Relay Agent.

   The CPE Router is not expected to implement:

   o  Support for transmission of Reconfigure messages on the LAN
      Interface.

   o  Any relay agent functions.

   o  Any DHCP authentication mechanisms.

   o  The server unicast option.

   o  Processing for user class or vendor class options received from
      clients.











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7.  Future Considerations

   This section presents additional use cases and associated
   requirements for an IPv6 CPE Router that should be given future
   consideration.

7.1.  IPv6 Prefix Sub-delegation

   In advanced home networks, users may deploy multiple routers.  To
   support those users or those deployment scenarios, the IPv6 CPE
   Router should have a mechanism to sub-delegate an IA_PD received from
   the Service Provider.  The exact mechanism is left for future
   consideration.

7.2.  Provide IPv6 Multicast

   IPv6 Multicast support will facilitate Service Provider delivery of
   live multimedia content to IPv6 Home Devices.  CPE Router support for
   IPv6 Multicast should be considered in the future.

7.3.  Transition and Tunneling Mechanisms

   As networks transition from IPv4 to IPv6, transition mechanisms may
   be required to continue providing customers with Internet service.
   In the future, the CPE Router may need to support some of these
   transition mechanisms, such as softwire [I-D.ietf-softwire-hs-
   framework-l2tpv2], Dual Stack Lite [I-D.ietf-softwire-dual-stack-
   lite], or NAT64.

7.4.  Provisioning Consistency Between DHCPv4 and DHCPv6

   In order to simplify DHCP provisioning for Service Providers, devices
   using DHCP should use the same client identifier, whether using
   DHCPv4 or DHCPv6.  Accordingly, a CPE Router that supports IPv4
   should support [RFC 4361] Client Identifiers for DHCPv4.  Since this
   draft does not discuss DHCPv4 provisioning, this requirement is left
   for future working group consideration.

7.5.  Offer Domain Name Service through an IPv6 CPE Router

   In an IPv6 environment, DNS will be an essential service for
   customers.  The CPE Router should be able to provide DNS service to
   consumer devices, either through a DNS proxy, recursive resolvers, or
   some other option.  The use cases for DNS support have not yet been
   defined, and should be considered in the future.






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8.  Security Considerations

   IPv6 CPE Router security considerations are addressed in
   [draft-ietf-v6ops-simple-security].















































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9.  IANA Considerations

   This document does not register any values in IANA registries.
















































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10.  Acknowledgements

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

   Scott Beuker, Rex Bullinger, Alain Durand, Katsunori Fukuoka, Kevin
   Johns, Stephen Kramer, Victor Kuarsingh, Jean-Francois Mule, John
   Pomeroy, Matt Schmitt, Cor Zwart

   This draft 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, Greg White
































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11.  References

11.1.  Normative References

   [I-D.ietf-dhc-container-opt]
              Droms, R., "Container Option for Server Configuration",
              draft-ietf-dhc-container-opt-05 (work in progress),
              March 2009.

   [I-D.ietf-v6ops-cpe-simple-security]
              Woodyatt, J., "Recommended Simple Security Capabilities in
              Customer Premises Equipment for  Providing Residential
              IPv6 Internet Service",
              draft-ietf-v6ops-cpe-simple-security-00 (work in
              progress), June 2007.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2710]  Deering, S., Fenner, W., and B. Haberman, "Multicast
              Listener Discovery (MLD) for IPv6", RFC 2710,
              October 1999.

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, May 2000.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC3646]  Droms, R., "DNS Configuration options for Dynamic Host
              Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
              December 2003.

   [RFC3736]  Droms, R., "Stateless Dynamic Host Configuration Protocol
              (DHCP) Service for IPv6", RFC 3736, April 2004.

   [RFC4075]  Kalusivalingam, V., "Simple Network Time Protocol (SNTP)
              Configuration Option for DHCPv6", RFC 4075, May 2005.

   [RFC4242]  Venaas, S., Chown, T., and B. Volz, "Information Refresh
              Time Option for Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 4242, November 2005.



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   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, September 2007.

   [RFC5006]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Option for DNS Configuration",
              RFC 5006, September 2007.

11.2.  Informative References

   [I-D.ietf-softwire-dual-stack-lite]
              Durand, A., Droms, R., Haberman, B., and J. Woodyatt,
              "Dual-stack lite broadband deployments post IPv4
              exhaustion", draft-ietf-softwire-dual-stack-lite-00 (work
              in progress), March 2009.

   [I-D.ietf-softwire-hs-framework-l2tpv2]
              Storer, B., Pignataro, C., Santos, M., Stevant, B., and J.
              Tremblay, "Softwire Hub & Spoke Deployment Framework with
              L2TPv2", draft-ietf-softwire-hs-framework-l2tpv2-13 (work
              in progress), April 2009.

   [RFC4361]  Lemon, T. and B. Sommerfeld, "Node-specific Client
              Identifiers for Dynamic Host Configuration Protocol
              Version Four (DHCPv4)", RFC 4361, February 2006.

   [RFC4943]  Roy, S., Durand, A., and J. Paugh, "IPv6 Neighbor
              Discovery On-Link Assumption Considered Harmful",
              RFC 4943, September 2007.
















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Authors' Addresses

   Chris Donley
   CableLabs
   858 Coal Creek Circle
   Louisville, CO  80027
   USA

   Email: c.donley@cablelabs.com


   Deepak Kharbanda
   CableLabs
   858 Coal Creek Circle
   Louisville, CO  80027
   USA

   Email: d.kharbanda@cablelabs.com


   John Jason Brzozowski
   Comcast Cable
   1360 Goshen Parkway
   West Chester, PA  19473
   USA

   Email: john_brzozowski@cable.comcast.com


   Yiu Lee
   Comcast Cable
   1500 Market St
   Philadelphia, PA  19102
   USA

   Email: yiu_lee@cable.comcast.com


   Jason Weil
   Cox Communications
   5575 Peachtree Dunwoody Road
   Atlanta, GA  30342
   USA

   Email: jason.weil@cox.com






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   Kirk Erichsen
   Time Warner Cable
   12101 Airport Way
   Broomfield, CO  80021
   USA

   Email: kirk.erichsen@twcable.com


   Lee Howard
   Time Warner Cable
   13241 Woodland Park Rd
   Herndon, VA  20171
   USA

   Email: william.howard@twcable.com


   Jean-Francois Tremblay
   Videotron
   300 Viger Ave E
   Montreal, PQ  PQ  H2X 3W4
   CA

   Email: trembjfr@videotron.com


























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