[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-palet-v6ops-transition-ipv4aas) 00 01 02 03 04 05 06 07 08

IPv6 Operations (v6ops)                                J. Palet Martinez
Internet-Draft                                          The IPv6 Company
Updates: 8026 (if approved)                                 H. M.-H. Liu
Intended status: Informational                      D-Link Systems, Inc.
Expires: December 15, 2018                                  M. Kawashima
                                                     NEC Platforms, Ltd.
                                                           June 13, 2018


Requirements for IPv6 Customer Edge Routers to Support IPv4 Connectivity
                              as-a-Service
                 draft-ietf-v6ops-transition-ipv4aas-02

Abstract

   This document specifies the IPv4 service continuity requirements for
   an IPv6 Customer Edge (CE) router, either provided by the service
   provider or thru the retail market.

   Specifically, this document extends the "Basic Requirements for IPv6
   Customer Edge Routers" in order to allow the provisioning of IPv6
   transition services for the support of "IPv4 as-a-Service" (IPv4aaS)
   by means of new transition mechanisms.  The document only covers
   transition technologies for delivering IPv4 in IPv6-only access
   networks, commonly called "IPv4 as-a-Service" (IPv4aaS), as required
   in a world where IPv4 addresses are no longer available, so hosts in
   the customer LANs with IPv4-only or IPv6-only applications or
   devices, requiring to communicate with IPv4-only services at the
   Internet, are still able to do so.

   In order to be able to prioritize, in a uniform way, among all the
   transition mechanisms, and to enable the service provider to enable/
   disable them, this document updates RFC8026.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."



Palet Martinez, et al.  Expires December 15, 2018               [Page 1]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   This Internet-Draft will expire on December 15, 2018.

Copyright Notice

   Copyright (c) 2018 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
   (https://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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language - Special Note  . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  General Requirements  . . . . . . . . . . . . . . . . . .   4
     3.2.  LAN-Side Configuration  . . . . . . . . . . . . . . . . .   4
     3.3.  Transition Technologies Support for IPv4 service
           continuity        (IPv4 as-a-Service - IPv4aaS) . . . . .   5
       3.3.1.  464XLAT . . . . . . . . . . . . . . . . . . . . . . .   6
       3.3.2.  Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . .   6
       3.3.3.  Lightweight 4over6 (lw4o6)  . . . . . . . . . . . . .   7
       3.3.4.  MAP-E . . . . . . . . . . . . . . . . . . . . . . . .   8
       3.3.5.  MAP-T . . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  IPv4 Multicast Support  . . . . . . . . . . . . . . . . . . .   9
   5.  UPnP Support  . . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Differences from RFC7084  . . . . . . . . . . . . . . . . . .  10
   7.  Update of RFC8026 . . . . . . . . . . . . . . . . . . . . . .  10
   8.  Code Considerations . . . . . . . . . . . . . . . . . . . . .  10
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   12. Annex A: Usage Scenarios  . . . . . . . . . . . . . . . . . .  11
   13. Annex B: End-User Network Architecture  . . . . . . . . . . .  13
   14. ANNEX C: Changes from -00 . . . . . . . . . . . . . . . . . .  16
   15. ANNEX D: Changes from -01 . . . . . . . . . . . . . . . . . .  16
   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     16.1.  Normative References . . . . . . . . . . . . . . . . . .  16
     16.2.  Informative References . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19



Palet Martinez, et al.  Expires December 15, 2018               [Page 2]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


1.  Introduction

   This document defines IPv4 service continuity features over an
   IPv6-only network, for a residential or small-office router, referred
   to as an "IPv6 Transition CE Router", in order to establish an
   industry baseline for transition features to be implemented on such a
   router.

   These routers are likely to rely upon "Basic Requirements for IPv6
   Customer Edge Routers" ([RFC7084]), so the scope of this document is
   to ensure the IPv4 "service continuity" support, in the LAN side and
   the access to IPv4-only Internet services from an IPv6-only access
   WAN even from IPv6-only applications or devices in the LAN side.

   This document covers a set of IP transition techniques required when
   ISPs have an IPv6-only access network.  This is a common situation in
   a world where IPv4 addresses are no longer available, so the service
   providers need to provision IPv6-only WAN access.  At the same time,
   they need to ensure that both IPv4-only and IPv6-only devices or
   applications in the customer networks, can still reach IPv4-only
   devices and applications in the Internet.

   This document specifies the IPv4 service continuity mechanisms to be
   supported by an IPv6 Transition CE Router, and relevant provisioning
   or configuration information differences from [RFC7084].

   This document is not a recommendation for service providers to use
   any specific transition mechanism.

   Automatic provisioning of more complex topology than a single router
   with multiple LAN interfaces may be handled by means of HNCP
   ([RFC7788]), which is out of the scope of this document.

   Service providers who specify feature sets for IPv6 Transition CE
   Router MAY specify a different set of features than those included in
   this document.  Since it is impossible to know prior to sale which
   transition mechanism a device will need over the lifetime of the
   device, IPv6 Transition CE Router intended for the retail market MUST
   support all of them.

   A complete description of "Usage Scenarios" and "End-User Network
   Architecture" is provided in Annex A and B, respectively.

1.1.  Requirements Language - Special 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



Palet Martinez, et al.  Expires December 15, 2018               [Page 3]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   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 to provide
   additional guidance to implementers regarding any protocol
   implementation required to produce a successful IPv6 Transition CE
   Router that interoperates successfully with a particular subset of
   currently deploying and planned common IPv6-only access networks.

2.  Terminology

   This document uses the same terms as in [RFC7084], with minor
   clarifications.

   "IPv4aaS" stands for "IPv4 as-a-Service", meaning transition
   technologies for delivering IPv4 in IPv6-only access networks.

   The term "IPv6 transition Customer Edge Router with IPv4aaS"
   (shortened as "IPv6 Transition CE Router") is defined as an "IPv6
   Customer Edge Router" that provides features for the delivery of IPv4
   services over an IPv6-only WAN network including IPv6-IPv4
   communications.

   The "WAN Interface" term used across this document, means that can
   also support link technologies based in Internet-layer (or higher-
   layers) "tunnels", such as IPv4-in-IPv6 tunnels.

3.  Requirements

   The IPv6 Transition CE Router MUST comply with [RFC7084] (Basic
   Requirements for IPv6 Customer Edge Routers).

3.1.  General Requirements

   A new general requirement is added, in order to ensure that the IPv6
   Transition CE Router respects the IPv6 prefix length as a parameter:

   G-6 The IPv6 Transition CE Router MUST comply with [RFC7608] (IPv6
   Prefix Length Recommendation for Forwarding).

3.2.  LAN-Side Configuration

   A new LAN requirement is added, which in fact is common in regular
   IPv6 Transition CE Router, and it is required by most of the
   transition mechanisms:

   L-15 The IPv6 Transition CE Router SHOULD implement a DNS proxy as
   described in [RFC5625] (DNS Proxy Implementation Guidelines).



Palet Martinez, et al.  Expires December 15, 2018               [Page 4]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


3.3.  Transition Technologies Support for IPv4 service continuity (IPv4
      as-a-Service - IPv4aaS)

   The main target of this document is the support of IPv6-only WAN
   access.  To enable legacy IPv4 functionality, this document also
   includes the support of IPv4-only devices and applications in the
   customers LANs, as well as IPv4-only services on the Internet.  Thus,
   both IPv4-only and the IPv6-only devices inside the IPv6 Transition
   CE Router are able to reach the IPv4-only services.

   This document takes no position on simultaneous operation of any
   transition mechanism and native IPv4.

   In order to seamlessly provide the IPv4 Service Continuity in
   Customer LANs, allowing an automated IPv6 transition mechanism
   provisioning, general transition requirements are added.

   General transition requirements:

   TRANS-1:  All the supported transition mechanisms MUST be disabled by
             default configuration of the IPv6 Transition CE Router.

   TRANS-2:  The IPv6 Transition CE Router MUST have a GUI and/or CLI
             option to manually enable/disable each of the supported
             transition mechanisms.

   TRANS-3:  The IPv6 Transition CE Router MUST support the DHCPv6 S46
             priority options described in [RFC8026] (Unified IPv4-in-
             IPv6 Softwire Customer Premises Equipment (CPE): A
             DHCPv6-Based Prioritization Mechanism).

   TRANS-4:  The IPv6 Transition CE Router, following Section 1.4 of
             [RFC8026], MUST check for a valid match in
             OPTION_S46_PRIORITY, which will allow configuring a
             transition mechanisms.  If 464XLAT [RFC6877] is supported,
             it MUST be included in the candidate list of possible S46
             mechanism, if one or more NAT64 prefixes are learnt by
             means of either [RFC7050] or [RFC7225].

   TRANS-5:  In order to allow the service provider to disable all the
             transition mechanisms, the IPv6 Transition CE Router MUST
             NOT enable any transition mechanisms if no match is found
             between the priority list and the candidate list.

   The following sections describe the requirements for supporting each
   one of the transition mechanisms.





Palet Martinez, et al.  Expires December 15, 2018               [Page 5]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


3.3.1.  464XLAT

   464XLAT [RFC6877] is a technique to provide IPv4 service over an
   IPv6-only access network without encapsulation.  This architecture
   assumes a NAT64 [RFC6146] (Stateful NAT64: Network Address and
   Protocol Translation from IPv6 Clients to IPv4 Servers) function
   deployed at the service provider or a third-party network.

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

   464XLAT requirements:

   464XLAT-1:  The IPv6 Transition CE Router MUST perform IPv4 Network
               Address Translation (NAT) on IPv4 traffic translated
               using the CLAT, unless a dedicated /64 prefix has been
               acquired, either using DHCPv6-PD [RFC3633] (IPv6 Prefix
               Options for DHCPv6) or by alternative means.

   464XLAT-2:  The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
               [RFC6970] (UPnP Internet Gateway Device - Port Control
               Protocol Interworking Function).

   464XLAT-3:  If PCP ([RFC6887]) is implemented, the IPv6 Transition CE
               Router MUST also implement [RFC7291] (DHCP Options for
               the PCP).  If no PCP server is configured, the IPv6
               Transition CE Router MAY verify if the default gateway,
               or the NAT64 is the PCP server.  A plain IPv6 mode is
               used to send PCP requests to the server.

   464XLAT-4:  The IPv6 Transition CE Router MUST implement [RFC7050]
               (Discovery of the IPv6 Prefix Used for IPv6 Address
               Synthesis) in order to discover the PLAT-side translation
               IPv4 and IPv6 prefix(es)/suffix(es).  The IPv6 Transition
               CE Router MUST follow [RFC7225] (Discovering NAT64 IPv6
               Prefixes Using the PCP), in order to learn the PLAT-side
               translation IPv4 and IPv6 prefix(es)/suffix(es) used by
               an upstream PCP-controlled NAT64 device.

3.3.2.  Dual-Stack Lite (DS-Lite)

   Dual-Stack Lite [RFC6333] enables both continued support for IPv4
   services and incentives for the deployment of IPv6.  It also de-
   couples IPv6 deployment in the service provider network from the rest
   of the Internet, making incremental deployment easier.  Dual-Stack
   Lite enables a broadband service provider to share IPv4 addresses
   among customers by combining two well-known technologies: IP in IP



Palet Martinez, et al.  Expires December 15, 2018               [Page 6]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   (IPv4-in-IPv6) and Network Address Translation (NAT).  It is expected
   that DS-Lite traffic is forwarded over the IPv6 Transition CE
   Router's native IPv6 WAN interface, and not encapsulated in another
   tunnel.

   The IPv6 Transition CE Router SHOULD implement DS-Lite [RFC6333]
   functionality.  If DS-Lite is supported, it MUST be implemented
   according to [RFC6333].  The following IPv6 Transition CE Router
   requirements also apply:

   DS-Lite requirements:

   DSLITE-1:  The IPv6 Transition CE Router MUST support configuration
              of DS-Lite via the DS-Lite DHCPv6 option [RFC6334] (DHCPv6
              Option for Dual-Stack Lite).  The IPv6 Transition CE
              Router MAY use other mechanisms to configure DS-Lite
              parameters.  Such mechanisms are outside the scope of this
              document.

   DSLITE-2:  The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
              [RFC6970] (UPnP Internet Gateway Device - Port Control
              Protocol Interworking Function).

   DSLITE-3:  If PCP ([RFC6887]) is implemented, the IPv6 Transition CE
              Router SHOULD also implement [RFC7291] (DHCP Options for
              the PCP).  If PCP ([RFC6887]) is implemented and a PCP
              server is not configured, the IPv6 Transition CE Router
              MUST assume, by default, that the AFTR is the PCP server.
              A plain IPv6 mode is used to send PCP requests to the
              server.

   DSLITE-4:  The IPv6 Transition CE Router MUST NOT perform IPv4
              Network Address Translation (NAT) on IPv4 traffic
              encapsulated using DS-Lite ([RFC6333]).

3.3.3.  Lightweight 4over6 (lw4o6)

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

   The IPv6 Transition CE Router SHOULD implement lw4o6 functionality.
   If DS-Lite is implemented, lw4o6 SHOULD be supported as well.  If
   lw4o6 is supported, it MUST be implemented according to [RFC7596].
   The following IPv6 Transition CE Router requirements also apply:




Palet Martinez, et al.  Expires December 15, 2018               [Page 7]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   Lw4o6 requirements:

   LW4O6-1:  The IPv6 Transition CE Router MUST support configuration of
             lw4o6 via the lw4o6 DHCPv6 options [RFC7598] (DHCPv6
             Options for Configuration of Softwire Address and Port-
             Mapped Clients).  The IPv6 Transition CE Router MAY use
             other mechanisms to configure lw4o6 parameters.  Such
             mechanisms are outside the scope of this document.

   LW4O6-2:  The IPv6 Transition CE Router MUST support the DHCPv4-over-
             DHCPv6 (DHCP 4o6) transport described in [RFC7341] (DHCPv4-
             over-DHCPv6 Transport).

   LW4O6-3:  The IPv6 Transition CE Router MAY support Dynamic
             Allocation of Shared IPv4 Addresses as described in
             [RFC7618] (Dynamic Allocation of Shared IPv4 Addresses).

3.3.4.  MAP-E

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

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

   MAP-E requirements:

   MAPE-1:  The IPv6 Transition CE Router MUST support configuration of
            MAP-E via the MAP-E DHCPv6 options [RFC7598] (DHCPv6 Options
            for Configuration of Softwire Address and Port-Mapped
            Clients).  The IPv6 Transition CE Router MAY use other
            mechanisms to configure MAP-E parameters.  Such mechanisms
            are outside the scope of this document.

   MAPE-2:  The IPv6 Transition CE Router MAY support Dynamic Allocation
            of Shared IPv4 Addresses as described in [RFC7618] (Dynamic
            Allocation of Shared IPv4 Addresses).

3.3.5.  MAP-T

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

   The IPv6 Transition CE Router SHOULD support MAP-T functionality.  If



Palet Martinez, et al.  Expires December 15, 2018               [Page 8]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   MAP-T is supported, it MUST be implemented according to [RFC7599].
   The following IPv6 Transition CE Router requirements also apply:

   MAP-T requirements:

   MAPT-1:  The IPv6 Transition CE Router MUST support configuration of
            MAP-T via the MAP-T DHCPv6 options [RFC7598] (DHCPv6 Options
            for Configuration of Softwire Address and Port-Mapped
            Clients).  The IPv6 Transition CE Router MAY use other
            mechanisms to configure MAP-T parameters.  Such mechanisms
            are outside the scope of this document.

   MAPT-2:  The IPv6 Transition CE Router MAY support Dynamic Allocation
            of Shared IPv4 Addresses as described in [RFC7618] (Dynamic
            Allocation of Shared IPv4 Addresses).

4.  IPv4 Multicast Support

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

   If the IPv6 Transition CE Router supports delivery of IPv4 multicast
   services, then it MUST support [RFC8114] (Delivery of IPv4 Multicast
   Services to IPv4 Clients over an IPv6 Multicast Network) and
   [RFC8115] (DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6
   Prefixes).

5.  UPnP Support

   UPnP SHOULD be disabled by default on the IPv6 Transition CE Router
   when using an IPv4aaS transition mechanism.

   UPnP MAY be enabled when a IPv6 Transition CE Router is configured to
   use a stateless mechanism that allows unsolicited inbound packets
   through to the CE, such as MAP or lw4o6, or when configured with 4 a
   port set containing all 65535 ports, e.g. with an IPv4 address
   sharing ratio of 1.

   If UPnP is enabled on a IPv6 Transition CE Router, the UPnP agent
   MUST reject any port mapping requests for ports outside of the port
   set allocated to the IPv6 Transition CE Router.

   UPnP MAY also be enabled on a IPv6 Transition CE Router configured
   for IPv4aaS mechanisms that support PCP [RFC6887], if implemented in
   conjunction with a method to control the external port mapping, such
   as IGD-PCP IWF [RFC6970].




Palet Martinez, et al.  Expires December 15, 2018               [Page 9]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   A IPv6 Transition CE Router that implements a UPnP agent, SHOULD
   support the Open Connectivity Foundation's IGD:2 specification,
   including the AddAnyPortMapping() function.

6.  Differences from RFC7084

   This document no longer consider the need to support 6rd ([RFC5969])
   and includes slightly different requirements for DS-LITE [RFC6333].

7.  Update of RFC8026

   [RFC8026] (Unified IPv4-in-IPv6 Softwire CPE: A DHCPv6-Based
   Prioritization Mechanism) specifies a DHCPv6 option in order to
   priorize among different transition mechanism, all them covered by
   this document, with the exception of 464XLAT [RFC6877].

   This document updates [RFC8026] in order to specify a new option code
   for 464XLAT [RFC6877], so the IPv6 Transition CE Router can use that
   as a simple mechanism for detecting if the CLAT need to be enabled/
   disabled and what priority 464XLAT has versus other transition
   mechanism included in the S46 Priority Option.

   In addition to that, as 464XLAT [RFC6877] doesn't have an specific
   DHCPv6 message for configuration options, this document changes the
   behaviour of Section 1.4.1 of [RFC8026], so 464XLAT is included in
   the candidate list of possible S46 mechanism, if one or more NAT64
   prefixes are learnt by means of either [RFC7050] or [RFC7225].

8.  Code Considerations

   One of the apparent main issues for vendors to include new
   functionalities, such as support for new transition mechanisms, is
   the lack of space in the flash (or equivalent) memory.  However, it
   has been confirmed from existing open source implementations
   (OpenWRT/LEDE, Linux, others), that adding the support for the new
   transitions mechanisms, requires around 10-12 Kbytes (because most of
   the code base is shared among several transition mechanisms already
   supported by [RFC7084]), as a single data plane is common to all
   them, which typically means about 0,15% of the existing code size in
   popular CEs already in the market.

   It is also clear that the new requirements don't have extra cost in
   terms of RAM memory, neither other hardware requirements such as more
   powerful CPUs.

   The other issue seems to be the cost of developing the code for those
   new functionalities.  However, at the time of writing this document,
   it has been confirmed that there are several open source versions of



Palet Martinez, et al.  Expires December 15, 2018              [Page 10]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   the required code for supporting the new transition mechanisms, and
   even several vendors already have implementations and provide it to
   ISPs, so the development cost is negligent, and only integration and
   testing cost may become a minor issue.

9.  Security Considerations

   The IPv6 Transition CE Router must comply with the Security
   Considerations as stated in [RFC7084], as well as those stated by
   each transition mechanism implemented by the IPv6 Transition CE
   Router.

10.  IANA Considerations

   IANA is instructed, by means of this document, to create a new Option
   Code for 464XLAT in the registry "Option Codes permitted in the S46
   Priority Option" as follows.

                    +-------------+--------------------+-----------+
                    | Option Code |   S46 Mechanism    | Reference |
                    +-------------+--------------------+-----------+
                    |      46     |      464XLAT       | [RFC6877] |
                    +-------------+--------------------+-----------+

                  Table 1: DHCPv6 Option Code for 464XLAT

11.  Acknowledgements

   Thanks to Mikael Abrahamsson, Fred Baker, Mohamed Boucadair, Brian
   Carpenter, Lee Howard, Richard Patterson, Barbara Stark, Ole Troan,
   James Woodyatt, and "TBD", for their review and comments in this and
   previous versions of this document.

12.  Annex A: Usage Scenarios

   The situation previously described, where there is ongoing IPv6
   deployment and lack of IPv4 addresses, is not happening at the same
   pace at every country, and even within every country, every ISP.  For
   different technical, financial, commercial/marketing and socio-
   economic reasons, each network is transitioning at their own pace,
   and nobody has a magic crystal ball, to make a guess.

   Different studies (for example [IPv6Survey]) also show that this is a
   changing situation, because in a single country, it may be that not
   all operators provide IPv6 support, and consumers may switch ISPs and
   use the same IPv6 Transition CE Router with an ISP that provides
   IPv4-only and an ISP that provides IPv6 plus IPv4aaS.




Palet Martinez, et al.  Expires December 15, 2018              [Page 11]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   So, it is clear that, to cover all those evolving situations, a IPv6
   Transition CE Router is required, at least from the perspective of
   the transition support, which can accommodate those changes.

   Moreover, because some services will remain IPv4-only for an
   undetermined time, and some service providers will remain IPv4-only
   for an undetermined period of time, IPv4 will be needed for an
   undetermined period of time.  There will be a need for CEs with
   support "IPv4 as-a-Service" for an undetermined period of time.

   This document is consequently, based on those premises, in order to
   ensure the continued transition from networks that today may provide
   access with dual-stack or IPv6-in-IPv4, as described in [RFC7084],
   and as an "extension" to it, evolving to an IPv6-only access with
   IPv4-as-a-Service.

   Considering that situation and different possible usage cases, the
   IPv6 Transition CE Router described in this document is expected to
   be used typically, in the following scenarios:

   1.  Residential/household, Small Office/Home Office (SOHO) and Small/
       Medium Enterprise (SME).  Common usage is any kind of Internet
       access (web, email, streaming, online gaming, etc.).

   2.  Residential/household and Small/Medium Enterprise (SME) with
       advanced requirements.  Same basic usage as for the previous
       case, however there may be requirements for allowing inbound
       connections (IP cameras, web, DNS, email, VPN, etc.).

   The above list is not intended to be comprehensive of all the
   possible usage scenarios, just an overall view.  In fact,
   combinations of the above usages are also possible, as well as
   situations where the same CE is used at different times in different
   scenarios or even different services providers that may use a
   different transition mechanism.

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

   However, in the case of IPv4aaS, because the usage of private
   addresses and NAT and even depending on the specific transition
   mechanism, it typically requires some degree of more complex manual
   configuration such as setting up a DMZ, virtual servers, or port/
   protocol forwarding.  In general, IPv4 CE Routers already provide GUI
   and/or CLI to manually configure them, or the possibility to setup
   the CE in bridge mode, so another CE behind it, takes care of that.



Palet Martinez, et al.  Expires December 15, 2018              [Page 12]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   It is out of the scope of this document the definition of any
   requirements for that.

   The main difference for a CE Router to support the above indicated
   scenarios and number of users, is related to the packet processing
   capabilities, performance, even other details such as the number of
   WAN/LAN interfaces, their maximum speed, memory for keeping tables or
   tracking connections, etc.  It is out of the scope of this document
   to classify them.

   The actual bandwidth capabilities of access technologies such as
   FTTH, cable and even 3GPP/LTE, allows the support of such scenarios,
   and indeed, is a very common situation that access networks and CE
   Router provided by the service provider are the same for SMEs and
   residential users.

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

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

13.  Annex B: End-User Network Architecture

   According to the descriptions in the preceding sections, 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 upstream, connected to the
   service provider network.

   From the perspective of an "IPv4 user" behind an IPv6 transition
   Customer Edge Router with IPv4aaS, this doesn't change.

   However, while a typical IPv4 NAT deployment by default blocks all



Palet Martinez, et al.  Expires December 15, 2018              [Page 13]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   incoming connections and may allow opening of ports using a Universal
   Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some
   other firewall control protocol, in the case of an IPv6-only access
   and IPv4aaS, that may not be feasible depending on specific
   transition mechanism details.  PCP (Port Control Protocol, [RFC6887])
   may be an alternative solution.

   Another consequence of using IPv4 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.  In the case of an IPv6-only
   access, there is no change on that if the transition mechanism keeps
   running the NAT interface towards the LAN side.

   More advanced 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.  Once again, this is true
   for both, IPv4 and IPv6.

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

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





















Palet Martinez, et al.  Expires December 15, 2018              [Page 14]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


                     +---------------+                      \
                     |   Service     |                       \
                     |   Provider    |                        | Service
                     |    Router     |                        | Provider
                     +-------+-------+                        | Network
                             |                               /
                             | Customer                     /
                             | Internet Connection         /
                             |
                      +------+--------+                    \
                      |     IPv6      |                     \
                      | Customer Edge |                      \
                      |    Router     |                      /
                      +---+-------+---+                     /
          Network A       |       |   Network B            |
    ---+----------------+-+-    --+---+-------------+--    |
       |                |             |             |       \
   +---+------+         |        +----+-----+ +-----+----+   \
   |IPv6 Host |         |        | IPv4 Host| |IPv4/IPv6 |   /
   |          |         |        |          | | Host     |  /
   +----------+         |        +----------+ +----------+ /
                        |                                 |
                 +------+--------+                        | End-User
                 |     IPv6      |                        | Network(s)
                 |    Router     |                         \
                 +------+--------+                          \
          Network C     |                                    \
    ---+-------------+--+---                                  |
       |             |                                        |
   +---+------+ +----+-----+                                  |
   |IPv6 Host | |IPv6 Host |                                 /
   |          | |          |                                /
   +----------+ +----------+                               /

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

   This architecture describes the:

   o  Basic capabilities of the IPv6 Transition CE Router

   o  Provisioning of the WAN interface connecting to the service
      provider

   o  Provisioning of the LAN interfaces

   The IPv6 Transition CE Router may be manually configured in an
   arbitrary topology with a dynamic routing protocol or using HNCP
   ([RFC7788]).  Automatic provisioning and configuration is described



Palet Martinez, et al.  Expires December 15, 2018              [Page 15]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   for a single IPv6 Transition CE Router only.

14.  ANNEX C: Changes from -00

   Section to be removed for WGLC.  Significant updates are:

   1.  ID-Nits: IANA section.

   2.  ID-Nits: RFC7084 reference removed from Abstract.

   3.  This document no longer updates RFC7084.

   4.  UPnP section reworded.

   5.  "CE Router" changed to "IPv6 Transition CE Router".

   6.  Reduced text in Annex A.

15.  ANNEX D: Changes from -01

   Section to be removed for WGLC.  Significant updates are:

   1.  TRANS requirements reworked in order to increase operator control
       and allow gradual transitioning from dual-stack to IPv6-only on
       specific customers.

   2.  New TRANS requirement so all the supported transition mechanisms
       are disabled by default, in order to facilitate the operator
       management.

   3.  New TRANS requirement in order to allow turning on/off each
       transition mechanism by the user.

   4.  Clarification on how to obtain multiple /64 for 464XLAT.

   5.  S46 priority update to RFC8026 for including 464XLAT and related
       changes in several sections.

16.  References

16.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.





Palet Martinez, et al.  Expires December 15, 2018              [Page 16]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


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

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

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

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
              April 2011, <https://www.rfc-editor.org/info/rfc6146>.

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

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

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

   [RFC6887]  Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
              P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
              DOI 10.17487/RFC6887, April 2013,
              <https://www.rfc-editor.org/info/rfc6887>.

   [RFC6970]  Boucadair, M., Penno, R., and D. Wing, "Universal Plug and
              Play (UPnP) Internet Gateway Device - Port Control
              Protocol Interworking Function (IGD-PCP IWF)", RFC 6970,
              DOI 10.17487/RFC6970, July 2013,
              <https://www.rfc-editor.org/info/rfc6970>.







Palet Martinez, et al.  Expires December 15, 2018              [Page 17]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


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

   [RFC7084]  Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
              Requirements for IPv6 Customer Edge Routers", RFC 7084,
              DOI 10.17487/RFC7084, November 2013,
              <https://www.rfc-editor.org/info/rfc7084>.

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

   [RFC7291]  Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
              the Port Control Protocol (PCP)", RFC 7291,
              DOI 10.17487/RFC7291, July 2014,
              <https://www.rfc-editor.org/info/rfc7291>.

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

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

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

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

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





Palet Martinez, et al.  Expires December 15, 2018              [Page 18]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


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

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

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

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

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

16.2.  Informative References

   [IPv6Survey]
              Palet Martinez, J., "IPv6 Deployment Survey", January
              2018,
              <https://indico.uknof.org.uk/event/41/contribution/5/
              material/slides/0.pdf>.

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

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

Authors' Addresses







Palet Martinez, et al.  Expires December 15, 2018              [Page 19]


Internet-Draft       IPv6 Transition CE for IPv4aaS            June 2018


   Jordi Palet Martinez
   The IPv6 Company
   Molino de la Navata, 75
   La Navata - Galapagar, Madrid  28420
   Spain

   Email: jordi.palet@theipv6company.com
   URI:   http://www.theipv6company.com/


   Hans M.-H. Liu
   D-Link Systems, Inc.
   17595 Mount Herrmann St.
   Fountain Valley, California  92708
   US

   Email: hans.liu@dlinkcorp.com
   URI:   http://www.dlink.com/


   Masanobu Kawashima
   NEC Platforms, Ltd.
   800, Shimomata
   Kakegawa-shi, Shizuoka  436-8501
   Japan

   Email: kawashimam@vx.jp.nec.com
   URI:   https://www.necplatforms.co.jp/en/























Palet Martinez, et al.  Expires December 15, 2018              [Page 20]


Html markup produced by rfcmarkup 1.127, available from https://tools.ietf.org/tools/rfcmarkup/