Internet Engineering Task Force                                 H. Singh
Internet-Draft                                                 W. Beebee
Intended status: Informational                       Cisco Systems, Inc.
Expires: November 12, December 6, 2010                                      C. Donley
                                                                B. Stark
                                                           O. Troan, Ed.
                                                     Cisco Systems, Inc.
                                                            May 11,
                                                            June 4, 2010

           Basic Requirements for IPv6 Customer Edge Routers


   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.

Status of this Memo

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

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   This Internet-Draft will expire on November 12, December 6, 2010.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Architecture . . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Current IPv4 End-user Network Architecture . . . . . . . .  4
     3.2.  IPv6 End-user Network Architecture . . . . . . . . . . . .  5
   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  General Requirements . . . . . . . . . . . . . . . . . . .  6
     4.2.  WAN Side Configuration . . . . . . . . . . . . . . . . . .  6
     4.3.  LAN Side Configuration . . . . . . . . . . . . . . . . . .  9
     4.4.  Security Considerations  . . . . . . . . . . . . . . . . . 11
   5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   This document defines basic IPv6 features for a residential or small
   office router referred to as an IPv6 CE router.  Typically these
   routers 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 [I-D.ietf-behave-v6v4-framework].
   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.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Terminology

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

   IPv6 Customer Edge router a node intended for home or small office
                             use which 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
                             Ethernets (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 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 Ethernets (simple or bridged), PPP
                             links, Frame Relay, or ATM networks as well
                             as Internet-layer (or higher-layer)
                             "tunnels", such as tunnels over IPv4 or
                             IPv6 itself.

3.  Architecture

3.1.  Current IPv4 End-user Network Architecture

   An end-user network will likely support both IPv4 and IPv6.  It is
   not expected that an end-user will change their existing network
   topology with the introduction of IPv6.  There are some differences
   in how IPv6 works and is provisioned which has implications for the
   network architecture.  A typical IPv4 end-user network consist 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 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, i.e. 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.

   Rewriting addresses on the edge of the network also allows for some
   rudimentary multi-homing; even though using NATs for multi-homing
   does not preserve connections during a fail-over event [RFC4864].

   Many existing routers support dynamic routing, 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 IPv6 should provide equivalent
   or better capabilities and functionality than the current IPv4

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

                 An example of a typical 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

   This architecture describes the:

   o  Basic capabilities of an IPv6 CE router

   o  Provisioning of the WAN interface connecting to the Service

   o  Provisioning of the LAN interfaces

   Unique Local IPv6 Unicast Addresses (ULA) [RFC4193] are used by hosts
   communicating within the End-user Network; this is functionally
   similar to RFC1918 addresses used within an IPv4 End-user Network.
   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.

   For IPv6 multicast traffic the IPv6 CE router may act as an 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 is described for a single IPv6 CE router only.

4.  Requirements

4.1.  General Requirements

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

   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 [I-D.ietf-6man-node-req-bis] specification.

   G-2:  The IPv6 CE router MUST implement ICMP 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 acquisition process.

4.2.  WAN Side Configuration

   The IPv6 CE router will need to support connectivity to one or more
   access network architectures.  This document describes an IPv6 CE
   router that is not specific to any particular architecture or Service
   Provider, and 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 IPCP for IPv4.  This section makes the
   assumption that the same mechanism will work for any link-layer, be
   it Ethernet, 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 or stateful
         interface address assignment ([RFC4862]/[RFC3315]). ([RFC4862] / [RFC3315]).

   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 of other routing information the IPv6 CE router MUST use
         Router Discovery as specified in [RFC4861] to discover a
         default router(s) and install 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:  DHCPv6 address assignment (IA_NA) and DHCPv6 prefix delegation
         (IA_PD) SHOULD be done as a single DHCPv6 session.

   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 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 SLAAC [RFC4862].

   WAA-2:  The IPv6 CE router MUST follow the recommendation in
           [I-D.ietf-6man-ipv6-subnet-model] 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

   WAA-4:  The IPv6 CE router MUST be able to support the following
           DHCPv6 options: IA_NA, Reconfigure Accept [RFC3315],
           DNS_SERVERS [RFC3646].

   WAA-5:  The IPv6 CE router SHOULD support the DHCPv6 SNTP option
           [RFC4075] and the Information Refresh Time Option [RFC4242].

   WAA-6:  If the IPv6 CE router receives an RA 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 is unable to assign address(es) through
           SLAAC it MAY do DHCPv6 address assignment (request an IA_NA)
           even if the M-flag is set to 0.

   WAA-8:  If the IPv6 CE router does not acquire global IPv6
           address(es) from either SLAAC or DHCPv6, then it MUST create
           global IPv6 address(es) from its delegated prefix(es) and
           configure those on one of its internal virtual network

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

   Prefix Delegation requirements:

   WPD-1:  The IPv6 CE router MUST support DHCPv6 prefix delegation
           requesting router behavior as specified in [RFC3633] (IA_PD

   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 MUST 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

   WPD-4:  The IPv6 CE router MUST always initiate DHCPv6 prefix
           delegation, regardless of the M and O-flags in a received
           Router Advertisement message.

   WPD-5:  If the IPv6 CE Router initiates DHCPv6 before receiving a
           Router Advertisement it MUST also request an IA_NA option in

   WPD-6:  If the delegated prefix(es) are aggregate route(s) of
           multiple, more-specific routes, the IPv6 CE router MUST
           discard packets that match the aggregate route(s), but not
           any of the more-specific routes.  In other words, the next-
           hop for the aggregate route(s) 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 according to section 3.1 [RFC4443] back to
                the source of the packet, if the packet is to be dropped
                due to this rule.

   WPD-7:  If the IPv6 CE router requests both an IA_NA and an IA_PD in
           DHCPv6, it MUST accept an IA_PD in DHCPv6 Advertise/Reply
           messages, even if the message does not contain any addresses
           (IA_NA options with status code equal to NoAddrsAvail).

   WPD-8:  By default an IPv6 CE router MUST NOT initiate any dynamic
           routing protocol on its WAN interface.

4.3.  LAN Side Configuration

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

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

   1.  Link-local addresses are 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.


   L-1:   The IPv6 CE router MUST support ULA addressing [RFC4193].

   L-2:   The IPv6 CE router MUST have a ULA prefix that it maintains
          consistently across reboots.

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

   L-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.

   L-5:   The IPv6 CE router MUST support router behavior according to
          Neighbor Discovery for IPv6 [RFC4861].

   L-6:   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-7:   The IPv6 CE router MUST make each LAN interface an advertising
          interface according to [RFC4861].

   L-8:   In Router Advertisements messages, the Prefix Information
          Option's A and L-flags MUST be set to 1 by default.

   L-9:   The A and L-flags setting SHOULD be user configurable.

   L-10:  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-11:  Unless the IPv6 CE router is configured to support the DHCPv6
          IA_NA option, it SHOULD set M=0 and O=1 in its Router
          Advertisement messages [RFC4861].

   L-12:  The IPv6 CE router MUST support providing DNS information in
          the DHCPv6 DNS_SERVERS option [RFC3646].

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

   L-14:  If the delegated prefix changes, i.e. the current prefix is
          replaced with a new prefix without any overlapping time
          period, then the IPv6 CE router MUST immediately advertise the
          old prefix with a preferred lifetime of 0 and a valid lifetime
          of 2 hours (which must be decremented in real time) in a
          Router Advertisement message.

   L-15:  The IPv6 CE router MUST send an ICMP Destination Unreachable
          Message, code 5 (Source address failed ingress/egress policy)
          for packets forwarded to it using an address from a prefix
          which has been deprecated.

4.4.  Security Considerations

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

   Security requirements:

   S-1:  The IPv6 CE router SHOULD support

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

5.  Acknowledgements

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

   Mikael Abrahamsson, Merete Asak, Scott Beuker, Mohamed Boucadair, Rex
   Bullinger, Brian Carpenter, Remi Denis-Courmont, Gert Doering, Alain
   Durand, Katsunori Fukuoka, Tony Hain, Thomas Herbst, Kevin Johns,
   Stephen Kramer, Victor Kuarsingh, Francois-Xavier Le Bail, David
   Miles, Shin Miyakawa, Jean-Francois Mule, Michael Newbery, Carlos
   Pignataro, John Pomeroy, Antonio Querubin, Teemu Savolainen, Matt
   Schmitt, Hiroki Sato, Mark Townsley, Bernie Volz, James Woodyatt, Dan
   Wing and 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 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.

7.  IANA Considerations

   This memo includes no request to IANA.

8.  References

8.1.  Normative References

              Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet
              Model: the Relationship between Links and Subnet
              Prefixes", draft-ietf-6man-ipv6-subnet-model-12 (work in
              progress), April 2010.

              Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
              Requirements RFC 4294-bis",
              draft-ietf-6man-node-req-bis-04 (work in progress),
              March 2010.

              Woodyatt, J., "Recommended Simple Security Capabilities in
              Customer Premises Equipment for Providing Residential IPv6
              Internet Service", draft-ietf-v6ops-cpe-simple-security-11
              (work in progress), April 2010.

   [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.

   [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.

   [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.

   [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.

   [RFC4864]  Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and
              E. Klein, "Local Network Protection for IPv6", RFC 4864,
              May 2007.

   [RFC5072]  S.Varada, Haskins, D., and E. Allen, "IP Version 6 over
              PPP", RFC 5072, September 2007.

8.2.  Informative References

              Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
              IPv4/IPv6 Translation",
              draft-ietf-behave-v6v4-framework-09 (work in progress),
              May 2010.

              UPnP Forum, "Universal Plug and Play (UPnP) Internet
              Gateway Device (IGD)", November 2001,

Authors' Addresses

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

   Phone: +1 978 936 1622

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

   Phone: +1 978 936 2030

   Chris Donley
   858 Coal Creek Circle
   Louisville, CO  80027


   Barbara Stark
   725 W Peachtree St
   Atlanta, GA  30308

   Ole Troan (editor)
   Cisco Systems, Inc.
   Veversmauet 8
   N-5017 BERGEN,