RFC7084

Internet Engineering Task Force (IETF) H. Singh Request for Comments: 7084 W. Beebee Obsoletes: 6204 Cisco Systems, Inc. Category: Informational C. Donley ISSN: 2070-1721 CableLabs

                                                            B. Stark
                                                                AT&T
                                                       November 2013

       Basic Requirements for IPv6 Customer Edge Routers

Abstract

This document specifies requirements for an IPv6 Customer Edge (CE) router. Specifically, the current version of this document focuses on the basic provisioning of an IPv6 CE router and the provisioning of IPv6 hosts attached to it. The document also covers IP transition technologies. Two transition technologies in RFC 5969's IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) and RFC 6333's Dual-Stack Lite (DS-Lite) are covered in the document. The document obsoletes RFC 6204.

Status of This Memo

This document is not an Internet Standards Track specification; it is published for informational purposes.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7084.

Copyright Notice

Copyright (c) 2013 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Introduction

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

These routers typically also support IPv4.

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

This document specifies how an IPv6 CE router automatically provisions its WAN interface, acquires address space for provisioning of its LAN interfaces, and fetches other configuration information from the service provider network. Automatic provisioning of more complex topology than a single router with multiple LAN interfaces is out of scope for this document.

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

The document also covers the IP transition technologies that were available at the time this document was written. Two transition technologies in 6rd RFC5969 and DS-Lite RFC6333 are covered in the document.

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.

Terminology

End-User Network one or more links attached to the IPv6 CE

                         router that connect IPv6 hosts.

IPv6 Customer Edge Router a node intended for home or small-office

                         use that forwards IPv6 packets not
                         explicitly addressed to itself.  The IPv6
                         CE router connects the end-user network to
                         a service provider network.

IPv6 Host any device implementing an IPv6 stack

                         receiving IPv6 connectivity through the
                         IPv6 CE router.

LAN Interface an IPv6 CE router's attachment to a link in

                         the end-user network.  Examples are
                         Ethernet (simple or bridged), 802.11
                         wireless, or other LAN technologies.  An
                         IPv6 CE router may have one or more
                         network-layer LAN interfaces.

Service Provider an entity that provides access to the

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

WAN Interface an IPv6 CE router's attachment to a link

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

Architecture

Current IPv4 End-User Network Architecture

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

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

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

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

IPv6 End-User Network Architecture

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

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

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

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

This architecture describes the:

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.

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

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 [MULTIHOMING-WITHOUT-NAT], 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.

Requirements

General Requirements

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

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

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.

WAN-Side Configuration

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

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

WAN-side requirements:

W-1: When the router is attached to the WAN interface link, it MUST

     act as an IPv6 host for the purposes of stateless RFC4862 or
     stateful 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 CE router SHOULD support a Port

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

Link-layer requirements:

WLL-1: If the WAN interface supports Ethernet encapsulation, then

       the IPv6 CE router MUST support IPv6 over Ethernet RFC2464.

WLL-2: If the WAN interface supports PPP encapsulation, the IPv6 CE

       router MUST support IPv6 over PPP RFC5072.

WLL-3: If the WAN interface supports PPP encapsulation, in a dual-

       stack environment with IPCP and IPV6CP running over one PPP
       logical channel, the Network Control Protocols (NCPs) MUST be
       treated as independent of each other and start and terminate
       independently.

Address assignment requirements:

WAA-1: The IPv6 CE router MUST support Stateless Address

        Autoconfiguration (SLAAC) RFC4862.

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 CE router
        implements NTP, it requests the NTP Server DHCPv6 option
        RFC5908 and uses the received list of servers as primary
        time reference, unless explicitly configured otherwise.  LAN
        side support of NTP is out of scope for this document.

WAA-6: If the IPv6 CE router receives a Router Advertisement

        message (described in RFC4861) with the M flag set to 1,
        the IPv6 CE router MUST do DHCPv6 address assignment
        (request an IA_NA option).

WAA-7: If the IPv6 CE router does not acquire a global IPv6

        address(es) from either SLAAC or DHCPv6, then it MUST create
        a global IPv6 address(es) from its delegated prefix(es) and
        configure those on one of its internal virtual network
        interfaces, unless configured to require a global IPv6
        address on the WAN interface.

WAA-8: The CE router MUST support the SOL_MAX_RT option 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.

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
       CE router to use DHCPv6 prefix delegation when the CE router
       has not received any RA or received an RA with the M and the
       O bits set to zero is out of scope for this document.

WPD-5: Any packet received by the CE router with a destination

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

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

WPD-6: If the IPv6 CE router requests both an IA_NA and an IA_PD

       option in DHCPv6, it MUST accept an IA_PD option in DHCPv6
       Advertise/Reply messages, even if the message does not
       contain any addresses, unless configured to only obtain its
       WAN IPv6 address via DHCPv6; see [DHCPv6-STATEFUL-ISSUES].

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.

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.

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.

L-12: 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-13: If the delegated prefix changes, i.e., the current prefix is

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

L-14: The IPv6 CE router MUST send an ICMPv6 Destination Unreachable

      message, code 5 (Source address failed ingress/egress policy)
      for packets forwarded to it that use an address from a prefix
      that has been invalidated.

Transition Technologies Support

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 CE router's native IPv4 WAN interface and not encapsulated in another tunnel.

The CE router SHOULD 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 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 CE router supports configuration mechanisms other than

       the 6rd DHCPv4 Option 212 (user-entered, TR-069 [TR-069],
       etc.), the 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: A 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
       migration period such as a migration 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 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.

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 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 CE router requirements also apply:

WAN requirements:

DLW-1: The 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.

DLW-2: The IPv6 CE router MUST NOT perform IPv4 Network Address

       Translation (NAT) on IPv4 traffic encapsulated using DS-Lite.

DLW-3: 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.

Security Considerations

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

Security requirements:

S-1: The IPv6 CE router SHOULD support RFC6092. In particular,

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

S-2: The IPv6 CE router 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 CE router firewall is configured to filter incoming

     tunneled data, the firewall SHOULD provide the capability to
     filter decapsulated packets from a tunnel.

Acknowledgements

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.

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.

References

Normative References

RFC1122 Braden, R., "Requirements for Internet Hosts -

          Communication Layers", STD 3, RFC 1122, October 1989.

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate

          Requirement Levels", BCP 14, RFC 2119, March 1997.

RFC2131 Droms, R., "Dynamic Host Configuration Protocol", RFC

          2131, March 1997.

RFC2464 Crawford, M., "Transmission of IPv6 Packets over Ethernet

          Networks", RFC 2464, December 1998.

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.

RFC3704 Baker, F. and P. Savola, "Ingress Filtering for Multihomed

          Networks", BCP 84, RFC 3704, March 2004.

RFC3736 Droms, R., "Stateless Dynamic Host Configuration Protocol

          (DHCP) Service for IPv6", RFC 3736, April 2004.

RFC4191 Draves, R. and D. Thaler, "Default Router Preferences and

          More-Specific Routes", RFC 4191, November 2005.

RFC4193 Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast

          Addresses", RFC 4193, October 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.

RFC4443 Conta, A., Deering, S., and M. Gupta, "Internet Control

          Message Protocol (ICMPv6) for the Internet Protocol
          Version 6 (IPv6) Specification", RFC 4443, March 2006.

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, August 2006.

RFC4632 Fuller, V. and T. Li, "Classless Inter-domain Routing

          (CIDR): The Internet Address Assignment and Aggregation
          Plan", BCP 122, RFC 4632, August 2006.

RFC4779 Asadullah, S., Ahmed, A., Popoviciu, C., Savola, P., and

          J. Palet, "ISP IPv6 Deployment Scenarios in Broadband
          Access Networks", RFC 4779, January 2007.

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.

RFC5072 Varada, S., Haskins, D., and E. Allen, "IP Version 6 over

          PPP", RFC 5072, September 2007.

RFC5905 Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network

          Time Protocol Version 4: Protocol and Algorithms
          Specification", RFC 5905, June 2010.

RFC5908 Gayraud, R. and B. Lourdelet, "Network Time Protocol (NTP)

          Server Option for DHCPv6", RFC 5908, June 2010.

RFC5942 Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet

          Model: The Relationship between Links and Subnet
          Prefixes", RFC 5942, July 2010.

RFC5969 Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4

          Infrastructures (6rd) -- Protocol Specification", RFC
          5969, August 2010.

RFC6092 Woodyatt, J., "Recommended Simple Security Capabilities in

          Customer Premises Equipment (CPE) for Providing
          Residential IPv6 Internet Service", RFC 6092, January
          2011.

RFC6106 Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,

          "IPv6 Router Advertisement Options for DNS Configuration",
          RFC 6106, November 2010.

RFC6177 Narten, T., Huston, G., and L. Roberts, "IPv6 Address

          Assignment to End Sites", BCP 157, RFC 6177, March 2011.

RFC6333 Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-

          Stack Lite Broadband Deployments Following IPv4
          Exhaustion", RFC 6333, August 2011.

RFC6334 Hankins, D. and T. Mrugalski, "Dynamic Host Configuration

          Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
          RFC 6334, August 2011.

RFC6434 Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node

          Requirements", RFC 6434, December 2011.

RFC6603 Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan,

          "Prefix Exclude Option for DHCPv6-based Prefix
          Delegation", RFC 6603, May 2012.

RFC6887 Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.

          Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
          2013.

RFC7083 Droms, R., "Modification to Default Values of SOL_MAX_RT

          and INF_MAX_RT", RFC 7083, November 2013.

Informative References

[DHCPv6-STATEFUL-ISSUES]

          Troan, O. and B. Volz, "Issues with multiple stateful
          DHCPv6 options", Work in Progress, May 2013.

[MULTIHOMING-WITHOUT-NAT]

          Troan, O., Ed., Miles, D., Matsushima, S., Okimoto, T.,
          and D. Wing, "IPv6 Multihoming without Network Address
          Translation", Work in Progress, December 2010.

RFC6144 Baker, F., Li, X., Bao, C., and K. Yin, "Framework for

          IPv4/IPv6 Translation", RFC 6144, April 2011.

[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/>.

Authors' Addresses

Hemant Singh Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA

Phone: +1 978 936 1622 EMail: [email protected] URI: http://www.cisco.com/

Wes Beebee Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA

Phone: +1 978 936 2030 EMail: [email protected] URI: http://www.cisco.com/

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

EMail: [email protected]

Barbara Stark AT&T 1057 Lenox Park Blvd. NE Atlanta, GA 30319 USA

EMail: [email protected]