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rfc:rfc6782

Internet Engineering Task Force (IETF) V. Kuarsingh, Ed. Request for Comments: 6782 Rogers Communications Category: Informational L. Howard ISSN: 2070-1721 Time Warner Cable

                                                         November 2012
                     Wireline Incremental IPv6

Abstract

 Operators worldwide are in various stages of preparing for or
 deploying IPv6 in their networks.  These operators often face
 difficult challenges related to IPv6 introduction, along with those
 related to IPv4 run-out.  Operators will need to meet the
 simultaneous needs of IPv6 connectivity and continue support for IPv4
 connectivity for legacy devices with a stagnant supply of IPv4
 addresses.  The IPv6 transition will take most networks from an IPv4-
 only environment to an IPv6-dominant environment with long transition
 periods varying by operator.  This document helps provide a framework
 for wireline providers who are faced with the challenges of
 introducing IPv6 along with meeting the legacy needs of IPv4
 connectivity, utilizing well-defined and commercially available IPv6
 transition technologies.

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/rfc6782.

Kuarsingh & Howard Informational [Page 1] RFC 6782 Wireline Incremental IPv6 November 2012

Copyright Notice

 Copyright (c) 2012 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.

Kuarsingh & Howard Informational [Page 2] RFC 6782 Wireline Incremental IPv6 November 2012

Table of Contents

 1. Introduction ....................................................4
 2. Operator Assumptions ............................................4
 3. Reasons and Considerations for a Phased Approach ................5
    3.1. Relevance of IPv6 and IPv4 .................................6
    3.2. IPv4 Resource Challenges ...................................6
    3.3. IPv6 Introduction and Operational Maturity .................7
    3.4. Service Management .........................................8
    3.5. Suboptimal Operation of Transition Technologies ............8
    3.6. Future IPv6 Network ........................................9
 4. IPv6 Transition Technology Analysis .............................9
    4.1. Automatic Tunneling Using 6to4 and Teredo .................10
    4.2. Carrier-Grade NAT (NAT444) ................................10
    4.3. 6rd .......................................................11
    4.4. Native Dual Stack .........................................11
    4.5. DS-Lite ...................................................12
    4.6. NAT64 .....................................................12
 5. IPv6 Transition Phases .........................................13
    5.1. Phase 0 - Foundation ......................................13
         5.1.1. Phase 0 - Foundation: Training .....................13
         5.1.2. Phase 0 - Foundation: System Capabilities ..........14
         5.1.3. Phase 0 - Foundation: Routing ......................14
         5.1.4. Phase 0 - Foundation: Network Policy and Security ..15
         5.1.5. Phase 0 - Foundation: Transition Architecture ......15
         5.1.6. Phase 0 - Foundation: Tools and Management .........16
    5.2. Phase 1 - Tunneled IPv6 ...................................16
         5.2.1. 6rd Deployment Considerations ......................17
    5.3. Phase 2 - Native Dual Stack ...............................19
         5.3.1. Native Dual Stack Deployment Considerations ........20
    5.4. Intermediate Phase for CGN ................................20
         5.4.1. CGN Deployment Considerations ......................22
    5.5. Phase 3 - IPv6-Only .......................................23
         5.5.1. DS-Lite ............................................23
         5.5.2. DS-Lite Deployment Considerations ..................24
         5.5.3. NAT64 Deployment Considerations ....................25
 6. Security Considerations ........................................26
 7. Acknowledgements ...............................................26
 8. References .....................................................26
    8.1. Normative References ......................................26
    8.2. Informative References ....................................26

Kuarsingh & Howard Informational [Page 3] RFC 6782 Wireline Incremental IPv6 November 2012

1. Introduction

 This document sets out to help wireline operators in planning their
 IPv6 deployments while ensuring continued support for IPv6-incapable
 consumer devices and applications.  This document identifies which
 technologies can be used incrementally to transition from IPv4-only
 to an IPv6-dominant environment with support for Dual Stack
 operation.  The end state or goal for most operators will be
 IPv6-only, but the path to this final state will depend heavily on
 the amount of legacy equipment resident in end networks and
 management of long-tail IPv4-only content.  Although no single plan
 will work for all operators, options listed herein provide a baseline
 that can be included in many plans.
 This document is intended for wireline environments that include
 cable, DSL, and/or fiber as the access method to the end consumer.
 This document attempts to follow the principles laid out in
 [RFC6180], which provides guidance on using IPv6 transition
 mechanisms.  This document will focus on technologies that enable and
 mature IPv6 within the operator's network, but it will also include a
 cursory view of IPv4 connectivity continuance.  This document will
 focus on transition technologies that are readily available in
 off-the-shelf Customer Premises Equipment (CPE) devices and
 commercially available network equipment.

2. Operator Assumptions

 For the purposes of this document, the authors assume the following:
  1. The operator is considering deploying IPv6 or is in the process of

deploying IPv6.

  1. The operator has a legacy IPv4 subscriber base that will continue

to exist for a period of time.

  1. The operator will want to minimize the level of disruption to the

existing and new subscribers.

  1. The operator may also want to minimize the number of technologies

and functions that are needed to mediate any given set of

    subscribers' flows (overall preference for native IP flows).
  1. The operator is able to run Dual Stack in its own core network and

is able to transition its own services to support IPv6.

Kuarsingh & Howard Informational [Page 4] RFC 6782 Wireline Incremental IPv6 November 2012

 Based on these assumptions, an operator will want to utilize
 technologies that minimize the need to tunnel, translate, or mediate
 flows to help optimize traffic flow and lower the cost impacts of
 transition technologies.  Transition technology selections should be
 made to mediate the non-dominant IP family flows and allow native
 routing (IPv4 and/or IPv6) to forward the dominant traffic whenever
 possible.  This allows the operator to minimize the cost of IPv6
 transition technologies by minimizing the transition technology
 deployment size.
 An operator may also choose to prefer more IPv6-focused models where
 the use of transition technologies is based on an effort to enable
 IPv6 at the base layer as soon as possible.  Some operators may want
 to promote IPv6 early on in the deployment and have IPv6 traffic
 perform optimally from the outset.  This desire would need to be
 weighed against the cost and support impacts of such a choice and the
 quality of experience offered to subscribers.

3. Reasons and Considerations for a Phased Approach

 When faced with the challenges described in the introduction,
 operators may want to consider a phased approach when adding IPv6 to
 an existing subscriber base.  A phased approach allows the operator
 to add in IPv6 while not ignoring legacy IPv4 connection
 requirements.  Some of the main challenges the operator will face
 include the following:
  1. IPv4 exhaustion may occur long before all traffic is able to be

delivered over IPv6, necessitating IPv4 address sharing.

  1. IPv6 will pose operational challenges, since some of the software

is quite new and has had short run time in large production

    environments and organizations are also not acclimatized to
    supporting IPv6 as a service.
  1. Connectivity modes will move from IPv4-only to Dual Stack in the

home, changing functional behaviors in the consumer network and

    increasing support requirements for the operator.
  1. Although IPv6 support on CPEs is a newer phenomenon, there is a

strong push by operators and the industry as a whole to enable

    IPv6 on devices.  As demand grows, IPv6 enablement will no longer
    be optional but will be necessary on CPEs.  Documents like
    [RFC6540] provide useful tools in the short term to help vendors
    and implementors understand what "IPv6 support" means.

Kuarsingh & Howard Informational [Page 5] RFC 6782 Wireline Incremental IPv6 November 2012

 These challenges will occur over a period of time, which means that
 the operator's plans need to address the ever-changing requirements
 of the network and subscriber demand.  Although phases will be
 presented in this document, not all operators may need to enable each
 discrete phase.  It is possible that characteristics in individual
 networks may allow certain operators to skip or jump to various
 phases.

3.1. Relevance of IPv6 and IPv4

 The delivery of high-quality unencumbered Internet service should be
 the primary goal for operators.  With the imminent exhaustion of
 IPv4, IPv6 will offer the highest quality of experience in the long
 term.  Even though the operator may be focused on IPv6 delivery, it
 should be aware that both IPv4 and IPv6 will play a role in the
 Internet experience during transition.  The Internet is made of many
 interconnecting systems, networks, hardware, software, and content
 sources -- all of which will support IPv6 at different rates.
 Many subscribers use older operating systems and hardware that
 support IPv4-only operation.  Internet subscribers don't buy IPv4 or
 IPv6 connections; they buy Internet connections, which demand the
 need to support both IPv4 and IPv6 for as long as the subscriber's
 home network demands such support.  The operator may be able to
 leverage one or the other protocol to help bridge connectivity on the
 operator's network, but the home network will likely demand both IPv4
 and IPv6 for some time.

3.2. IPv4 Resource Challenges

 Since connectivity to IPv4-only endpoints and/or content will remain
 common, IPv4 resource challenges are of key concern to operators.
 The lack of new IPv4 addresses for additional devices means that
 meeting the growth in demand of IPv4 connections in some networks
 will require address sharing.
 Networks are growing at different rates, including those in emerging
 markets and established networks based on the proliferation of
 Internet-based services and devices.  IPv4 address constraints will
 likely affect many, if not most, operators at some point, increasing
 the benefits of IPv6.  IPv4 address exhaustion is a consideration
 when selecting technologies that rely on IPv4 to supply IPv6
 services, such as 6rd (IPv6 Rapid Deployment on IPv4 Infrastructures)
 [RFC5969].  Additionally, if native Dual Stack is considered by the
 operator, challenges related to IPv4 address exhaustion remain a
 concern.

Kuarsingh & Howard Informational [Page 6] RFC 6782 Wireline Incremental IPv6 November 2012

 Some operators may be able to reclaim small amounts of IPv4 addresses
 through addressing efficiencies in the network, although this will
 have few lasting benefits to the network and will not meet longer-
 term connectivity needs.  Secondary markets for IPv4 addresses have
 also begun to arise, but it's not well understood how this will
 complement overall demand for Internet growth.  Address transfers
 will also be subject to market prices and transfer rules governed by
 the Regional Registries.
 The lack of new global IPv4 address allocations will therefore force
 operators to support some form of IPv4 address sharing and may impact
 technological options for transition once the operator runs out of
 new IPv4 addresses for assignment.

3.3. IPv6 Introduction and Operational Maturity

 The introduction of IPv6 will require new operational practices.  The
 IPv4 environment we have today was built over many years and matured
 by experience.  Although many of these experiences are transferable
 from IPv4 to IPv6, new experience and practices specific to IPv6 will
 be needed.
 Engineering and operational staff will need to develop experience
 with IPv6.  Inexperience may lead to early IPv6 deployment
 instability, and operators should consider this when selecting
 technologies for initial transition.  Operators may not want to
 subject their mature IPv4 service to a "new IPv6" path initially
 while it may be going through growing pains.  Dual Stack Lite
 (DS-Lite) [RFC6333] and NAT64 [RFC6146] are both technologies that
 require IPv6 to support connectivity to IPv4 endpoints or content
 over an IPv6-only access network.
 Further, some of these transition technologies are new and require
 refinement within running code.  Deployment experience is required to
 expose bugs and stabilize software in production environments.  Many
 supporting systems are also under development and have newly
 developed IPv6 functionality, including vendor implementations of
 DHCPv6, management tools, monitoring systems, diagnostic systems, and
 logging, along with other elements.
 Although the base technological capabilities exist to enable and run
 IPv6 in most environments, organizational experience is low.  Until
 such time as each key technical member of an operator's organization
 can identify IPv6 and can understand its relevance to the IP service
 offering, how it operates, and how to troubleshoot it, the deployment
 needs to mature and may be subject to events that impact subscribers.
 This fact should not incline operators to delay their IPv6 deployment

Kuarsingh & Howard Informational [Page 7] RFC 6782 Wireline Incremental IPv6 November 2012

 but should drive them to deploy IPv6 sooner, to gain much-needed
 experience before IPv6 is the only viable way to connect new hosts to
 the network.
 It should also be noted that although many transition technologies
 may be new, and some code related to access environments may be new,
 there is a large segment of the networking fabric that has had IPv6
 available for a long period of time and has had extended exposure in
 production.  Operators may use this to their advantage by first
 enabling IPv6 in the core network and then working outward towards
 the subscriber edge.

3.4. Service Management

 Services are managed within most networks and are often based on the
 gleaning and monitoring of IPv4 addresses assigned to endpoints.
 Operators will need to address such management tools, troubleshooting
 methods, and storage facilities (such as databases) to deal with not
 only new address types containing 128-bit IPv6 addresses [RFC2460]
 but often both IPv4 and IPv6 at the same time.  Examination of
 address types, and recording delegated prefixes along with single
 address assignments, will likely require additional development.
 With any Dual Stack service -- whether native, 6rd-based, DS-Lite,
 NAT64, or some other service -- two address families may need to be
 managed simultaneously to help provide the full Internet experience.
 This would indicate that IPv6 management is not just a simple add-in
 but needs to be well integrated into the service management
 infrastructure.  In the early transition phases, it's quite likely
 that many systems will be missed, and that IPv6 services will go
 unmonitored and impairments will go undetected.
 These issues may be worthy of consideration when selecting
 technologies that require IPv6 as the base protocol to deliver IPv4
 connectivity.  Instability of the IPv6 service in such a case would
 impact IPv4 services.

3.5. Suboptimal Operation of Transition Technologies

 Native delivery of IPv4 and IPv6 provides a solid foundation for
 delivery of Internet services to subscribers, since native IP paths
 are well understood and networks are often optimized to send such
 traffic efficiently.  Transition technologies, however, may alter the
 normal path of traffic or reduce the path MTU, removing many network
 efficiencies built for native IP flows.  Tunneling and translation
 devices may not be located on the most optimal path in line with the

Kuarsingh & Howard Informational [Page 8] RFC 6782 Wireline Incremental IPv6 November 2012

 natural traffic flow (based on route computation) and therefore may
 increase latency.  These paths may also introduce additional points
 of failure.
 Generally, the operator will want to deliver native IPv6 as soon as
 possible and utilize transition technologies only when required.
 Transition technologies may be used to provide continued access to
 IPv4 via tunneling and/or translation or may be used to deliver IPv6
 connectivity.  The delivery of Internet or internal services should
 be considered by the operator, since supplying connections using a
 transition technology will reduce overall performance for the
 subscriber.
 When choosing between various transition technologies, operators
 should consider the benefits and drawbacks of each option.  Some
 technologies, like Carrier-Grade NAT (CGN)/NAT444, utilize many
 existing addressing and management practices.  Other options, such as
 DS-Lite and NAT64, remove the IPv4 addressing requirement to the
 subscriber premises device but require IPv6 to be operational and
 well supported.

3.6. Future IPv6 Network

 An operator should also be aware that longer-term plans may include
 IPv6-only operation in all or much of the network.  The IPv6-only
 operation may be complemented by technologies such as NAT64 for long-
 tail IPv4 content reach.  This longer-term view may be distant to
 some but should be considered when planning out networks, addressing,
 and services.  The needs and costs of maintaining two IP stacks will
 eventually become burdensome, and simplification will be desirable.
 Operators should plan for this state and not make IPv6 inherently
 dependent on IPv4, as this would unnecessarily constrain the network.
 Other design considerations and guidelines for running an IPv6
 network should also be considered by the operator.  Guidance on
 designing an IPv6 network can be found in [IPv6-DESIGN] and
 [IPv6-ICP-ASP-GUIDANCE].

4. IPv6 Transition Technology Analysis

 Operators should understand the main transition technologies for IPv6
 deployment and IPv4 run-out.  This document provides a brief
 description of some of the mainstream and commercially available
 options.  This analysis is focused on the applicability of
 technologies to deliver residential services and less focused on
 commercial access, wireless, or infrastructure support.

Kuarsingh & Howard Informational [Page 9] RFC 6782 Wireline Incremental IPv6 November 2012

 This document focuses on those technologies that are commercially
 available and in deployment.

4.1. Automatic Tunneling Using 6to4 and Teredo

 Even when operators may not be actively deploying IPv6, automatic
 mechanisms exist on subscriber operating systems and CPE hardware.
 Such technologies include 6to4 [RFC3056], which is most commonly used
 with anycast relays [RFC3068].  Teredo [RFC4380] is also used widely
 by many Internet hosts.
 Documents such as [RFC6343] have been written to help operators
 understand observed problems with 6to4 deployments and provide
 guidelines on how to improve their performance.  An operator may want
 to provide local relays for 6to4 and/or Teredo to help improve the
 protocol's performance for ambient traffic utilizing these IPv6
 connectivity methods.  Experiences such as those described in
 [COMCAST-IPv6-EXPERIENCES] show that local relays have proved
 beneficial to 6to4 protocol performance.
 Operators should also be aware of breakage cases for 6to4 if
 non-[RFC1918] addresses are used within CGN/NAT444 zones.  Many
 off-the-shelf CPEs and operating systems may turn on 6to4 without a
 valid return path to the originating (local) host.  This particular
 use case can occur if any space other than [RFC1918] is used,
 including Shared Address Space [RFC6598] or space registered to
 another organization (squat space).  The operator can use 6to4
 Provider Managed Tunnels (6to4-PMT) [RFC6732] or attempt to block
 6to4 operation entirely by blocking the anycast ranges associated
 with [RFC3068].

4.2. Carrier-Grade NAT (NAT444)

 Carrier-Grade NAT (CGN), specifically as deployed in a NAT444
 scenario [CGN-REQS], may prove beneficial for those operators who
 offer Dual Stack services to subscriber endpoints once they exhaust
 their pools of IPv4 addresses.  CGNs, and address sharing overall,
 are known to cause certain challenges for the IPv4 service [RFC6269]
 [NAT444-IMPACTS] but may be necessary, depending on how an operator
 has chosen to deal with IPv6 transition and legacy IPv4 connectivity
 requirements.
 In a network where IPv4 address availability is low, CGN/NAT444 may
 provide continued access to IPv4 endpoints.  Some of the advantages
 of using CGN/NAT444 include similarities in provisioning and

Kuarsingh & Howard Informational [Page 10] RFC 6782 Wireline Incremental IPv6 November 2012

 activation models.  IPv4 hosts in a CGN/NAT444 deployment will
 likely inherit the same addressing and management procedures as
 legacy IPv4 globally addressed hosts (i.e., DHCPv4, DNS (v4), TFTP,
 TR-069, etc.).

4.3. 6rd

 6rd [RFC5969] provides a way of offering IPv6 connectivity to
 subscriber endpoints when native IPv6 addressing on the access
 network is not yet possible.  6rd provides tunneled connectivity for
 IPv6 over the existing IPv4 path.  As the access edge is upgraded and
 subscriber premises equipment is replaced, 6rd can be replaced by
 native IPv6 connectivity.  6rd can be delivered on top of a CGN/
 NAT444 deployment, but this would cause all traffic to be subject to
 some type of transition technology.
 6rd may also be advantageous during the early transition period while
 IPv6 traffic volumes are low.  During this period, the operator can
 gain experience with IPv6 in the core network and improve the
 operator's peering framework to match those of the IPv4 service.  6rd
 scales by adding relays to the operator's network.  Another advantage
 of 6rd is that the operator does not need a DHCPv6 address assignment
 infrastructure and does not need to support IPv6 routing to the CPE
 to support a delegated prefix (as it's derived from the IPv4 address
 and other configuration parameters).
 Client support is required for 6rd operation and may not be available
 on deployed hardware.  6rd deployments may require the subscriber or
 operator to replace the CPE.  6rd will also require parameter
 configuration that can be powered by the operator through DHCPv4,
 manually provisioned on the CPE, or automatically provisioned through
 some other means.  Manual provisioning would likely limit deployment
 scale.

4.4. Native Dual Stack

 Native Dual Stack is often referred to as the "gold standard" of IPv6
 and IPv4 delivery.  It is a method of service delivery that is
 already used in many existing IPv6 deployments.  Native Dual Stack
 does, however, require that native IPv6 be delivered through the
 access network to the subscriber premises.  This technology option is
 desirable in many cases and can be used immediately if the access
 network and subscriber premises equipment support native IPv6.

Kuarsingh & Howard Informational [Page 11] RFC 6782 Wireline Incremental IPv6 November 2012

 An operator who runs out of IPv4 addresses to assign to subscribers
 will not be able to provide traditional native Dual Stack
 connectivity for new subscribers.  In Dual Stack deployments where
 sufficient IPv4 addresses are not available, CGN/NAT444 can be used
 on the IPv4 path.
 Delivering native Dual Stack would require the operator's core and
 access networks to support IPv6.  Other systems, like DHCP, DNS, and
 diagnostic/management facilities, need to be upgraded to support IPv6
 as well.  The upgrade of such systems may often be non-trivial and
 costly.

4.5. DS-Lite

 DS-Lite [RFC6333] is based on a native IPv6 connection model where
 IPv4 services are supported.  DS-Lite provides tunneled connectivity
 for IPv4 over the IPv6 path between the subscriber's network device
 and a provider-managed gateway (Address Family Transition Router
 (AFTR)).
 DS-Lite can only be used where there is a native IPv6 connection
 between the AFTR and the CPE.  This may mean that the technology's
 use may not be viable during early transition if the core or access
 network lacks IPv6 support.  During the early transition period, a
 significant amount of content and services may by IPv4-only.
 Operators may be sensitive to this and may not want the newer IPv6
 path to be the only bridge to IPv4 at that time, given the potential
 impact.  The operator may also want to make sure that most of its
 internal services and a significant amount of external content are
 available over IPv6 before deploying DS-Lite.  The availability of
 services on IPv6 would help lower the demand on the AFTRs.
 By sharing IPv4 addresses among multiple endpoints, like CGN/NAT444,
 DS-Lite can facilitate continued support of legacy IPv4 services even
 after IPv4 address run-out.  There are some functional considerations
 to take into account with DS-Lite, such as those described in
 [NAT444-IMPACTS] and in [DSLITE-DEPLOYMENT].
 DS-Lite requires client support on the CPE to function.  The ability
 to utilize DS-Lite will be dependent on the operator providing
 DS-Lite-capable CPEs or retail availability of the supported client
 for subscriber-acquired endpoints.

4.6. NAT64

 NAT64 [RFC6146] provides the ability to connect IPv6-only connected
 clients and hosts to IPv4 servers without any tunneling.  NAT64
 requires that the host and home network support IPv6-only modes of

Kuarsingh & Howard Informational [Page 12] RFC 6782 Wireline Incremental IPv6 November 2012

 operation.  Home networks do not commonly contain equipment that is
 100% IPv6-capable.  It is also not anticipated that common home
 networks will be ready for IPv6-only operation for a number of years.
 However, IPv6-only networking can be deployed by early adopters or
 highly controlled networks [RFC6586].
 Viability of NAT64 will increase in wireline networks as consumer
 equipment is replaced by IPv6-capable versions.  There are incentives
 for operators to move to IPv6-only operation, when feasible; these
 include the simplicity of a single-stack access network.

5. IPv6 Transition Phases

 The phases described in this document are not provided as a rigid set
 of steps but are considered a guideline that should be analyzed by
 operators planning their IPv6 transition.  Operators may choose to
 skip steps based on technological capabilities within their specific
 networks (residential/corporate, fixed/mobile), their business
 development perspectives (which may affect the pace of migration
 towards full IPv6), or a combination thereof.
 The phases are based on the expectation that IPv6 traffic volume may
 initially be low, and operator staff will gain experience with IPv6
 over time.  As traffic volumes of IPv6 increase, IPv4 traffic volumes
 will decline (in percentage relative to IPv6), until IPv6 is the
 dominant address family used.  Operators may want to keep the traffic
 flow for the dominant traffic class (IPv4 vs. IPv6) native to help
 manage costs related to transition technologies.  The cost of using
 multiple technologies in succession to optimize each stage of the
 transition should also be compared against the cost of changing and
 upgrading subscriber connections.
 Additional guidance and information on utilizing IPv6 transition
 mechanisms can be found in [RFC6180].  Also, guidance on incremental
 CGN for IPv6 transition can be found in [RFC6264].

5.1. Phase 0 - Foundation

5.1.1. Phase 0 - Foundation: Training

 Training is one of the most important steps in preparing an
 organization to support IPv6.  Most people have little experience
 with IPv6, and many do not even have a solid grounding in IPv4.  The
 implementation of IPv6 will likely produce many challenges due to
 immature code on hardware, and the evolution of many applications and
 systems to support IPv6.  To properly deal with these impending or
 current challenges, organizations must train their staff on IPv6.

Kuarsingh & Howard Informational [Page 13] RFC 6782 Wireline Incremental IPv6 November 2012

 Training should also be provided within reasonable timelines from the
 actual IPv6 deployment.  This means the operator needs to plan in
 advance as it trains the various parts of its organization.  New
 technology and engineering staff often receive little training
 because of their depth of knowledge but must at least be provided
 opportunities to read documentation, architectural white papers, and
 RFCs.  Operations personnel who support the network and other systems
 need to be trained closer to the deployment timeframes so that they
 immediately use their newfound knowledge before forgetting.
 Subscriber support staff would require much more basic but large-
 scale training, since many organizations have massive call centers to
 support the subscriber base.  Tailored training will also be required
 for marketing and sales staff to help them understand IPv6 and build
 it into the product development and sales process.

5.1.2. Phase 0 - Foundation: System Capabilities

 An important component with any IPv6 network architecture and
 implementation is the assessment of the hardware and operating
 capabilities of the deployed equipment (and software).  The
 assessment needs to be conducted irrespective of how the operator
 plans to transition its network.  The capabilities of the install
 base will, however, impact what technologies and modes of operation
 may be supported and therefore what technologies can be considered
 for the transition.  If some systems do not meet the needs of the
 operator's IPv6 deployment and/or transition plan, the operator may
 need to plan for replacement and/or upgrade of those systems.

5.1.3. Phase 0 - Foundation: Routing

 The network infrastructure will need to be in place to support IPv6.
 This includes the routed infrastructure, along with addressing
 principles, routing principles, peering policy, and related network
 functions.  Since IPv6 is quite different from IPv4 in several ways,
 including the number of addresses that are made available, careful
 attention to a scalable and manageable architecture is needed.  One
 such change is the notion of a delegated prefix, which deviates from
 the common single-address phenomenon in IPv4-only deployments.
 Deploying prefixes per CPE can load the routing tables and require a
 routing protocol or route gleaning to manage connectivity to the
 subscriber's network.  Delegating prefixes can be of specific
 importance in access network environments where downstream
 subscribers often move between access nodes, raising the concern of
 frequent renumbering and/or managing movement of routed prefixes
 within the network (common in cable-based networks).

Kuarsingh & Howard Informational [Page 14] RFC 6782 Wireline Incremental IPv6 November 2012

5.1.4. Phase 0 - Foundation: Network Policy and Security

 Many, but not all, security policies will map easily from IPv4 to
 IPv6.  Some new policies may be required for issues specific to IPv6
 operation.  This document does not highlight these specific issues
 but raises the awareness that they are to be taken into consideration
 and should be addressed when delivering IPv6 services.  Other IETF
 documents, such as [RFC4942], [RFC6092], and [RFC6169], are excellent
 resources.

5.1.5. Phase 0 - Foundation: Transition Architecture

 Operators should plan out their transition architecture in advance
 (with room for flexibility) to help optimize how they will build out
 and scale their networks.  Should operators consider multiple
 technologies, like CGN/NAT444, DS-Lite, NAT64, and 6rd, they may want
 to plan out where network resident equipment may be located and
 potentially choose locations that can be used for all functional
 roles (i.e., placement of a NAT44 translator, AFTR, NAT64 gateway,
 and 6rd relays).  Although these functions are not inherently
 connected, additional management, diagnostic, and monitoring
 functions can be deployed alongside the transition hardware without
 the need to distribute these functions to an excessive or divergent
 number of locations.
 This approach may also prove beneficial if traffic patterns change
 rapidly in the future, as operators may need to evolve their
 transition infrastructure faster than originally anticipated.  One
 such example may be the movement from a CGN/NAT44 model (Dual Stack)
 to DS-Lite.  Since both traffic sets require a translation function
 (NAT44), synchronized pool management, routing, and management system
 positioning can allow rapid movement (the technological means to
 re-provision the subscriber notwithstanding).
 Operators should inform their vendors of what technologies they plan
 to support over the course of the transition to make sure the
 equipment is suited to support those modes of operation.  This is
 important for both network gear and subscriber premises equipment.
 Operators should also plan their overall strategy to meet the target
 needs of an IPv6-only deployment.  As traffic moves to IPv6, the
 benefits of only a single stack on the access network may eventually
 justify the removal of IPv4 for simplicity.  Planning for this
 eventual model, no matter how far off this may be, will help
 operators embrace this end state when needed.

Kuarsingh & Howard Informational [Page 15] RFC 6782 Wireline Incremental IPv6 November 2012

5.1.6. Phase 0 - Foundation: Tools and Management

 The operator should thoroughly analyze all provisioning and
 management systems to develop requirements for each phase.  This will
 include concepts related to the 128-bit IPv6 address, the notation of
 an assigned IPv6 prefix (Prefix Delegation), and the ability to
 detect either or both address families when determining if a
 subscriber has full Internet service.
 If an operator stores usage information, this would need to be
 aggregated to include both IPv4 and IPv6 information as both address
 families are assigned to the same subscriber.  Tools that verify
 connectivity may need to query the IPv4 and IPv6 addresses.

5.2. Phase 1 - Tunneled IPv6

 Tunneled access to IPv6 can be regarded as an early-stage transition
 option by operators.  Many network operators can deploy native IPv6
 from the access edge to the peering edge fairly quickly but may not
 be able to offer IPv6 natively to the subscriber edge device.  During
 this period of time, tunneled access to IPv6 is a viable alternative
 to native IPv6.  It is also possible that operators may be rolling
 out IPv6 natively to the subscriber edge, but the time involved may
 be long, due to logistics and other factors.  Even while carefully
 rolling out native IPv6, operators can deploy relays for automatic
 tunneling technologies like 6to4 and Teredo.  Where native IPv6 to
 the access edge is a longer-term project, operators can consider 6rd
 [RFC5969] as an option to offer in-home IPv6 access.  Note that 6to4
 and Teredo have different address selection [RFC6724] behaviors than
 6rd.  Additional guidelines on deploying and supporting 6to4 can be
 found in [RFC6343].
 The operator can deploy 6rd relays into the network and scale them as
 needed to meet the early subscriber needs of IPv6.  Since 6rd
 requires the upgrade or replacement of CPE devices, the operator may
 want to ensure that the CPE devices support not just 6rd but native
 Dual Stack and other tunneling technologies, such as DS-Lite, if
 possible [IPv6-CE-RTR-REQS].  6rd clients are becoming available in
 some retail channel products and within the original equipment
 manufacturer (OEM) market.  Retail availability of 6rd is important,
 since not all operators control or have influence over what equipment
 is deployed in the consumer home network.  The operator can support
 6rd access with unmanaged devices using DHCPv4 Option 212
 (OPTION_6RD) [RFC5969].

Kuarsingh & Howard Informational [Page 16] RFC 6782 Wireline Incremental IPv6 November 2012

                                     +--------+         -----
                                     |        |       /       \
                     Encap IPv6 Flow |  6rd   |      |  IPv6   |
                              - - -> | Relay  | <- > |   Net   |
        +---------+         /        |        |       \       /
        |         |        /         +--------+         -----
        |   6rd   + <-----                              -----
        |         |                                   /       \
        |  Client |         IPv4 Flow                |  IPv4   |
        |         + < - - - - - - - - - - - - - - -> |   Net   |
        |         |                                   \       /
        +---------+                                     -----
                       Figure 1: 6rd Basic Model
 6rd used as an initial transition technology also provides the added
 benefit of a deterministic IPv6 prefix based on the IPv4 assigned
 address.  Many operational tools are available or have been built to
 identify what IPv4 (often dynamic) address was assigned to a
 subscriber CPE.  So, a simple tool and/or method can be built to help
 identify the IPv6 prefix using the knowledge of the assigned IPv4
 address.
 An operator may choose to not offer internal services over IPv6 if
 tunneled access to IPv6 is used, since some services generate a large
 amount of traffic.  Such traffic may include video content, like
 IPTV.  By limiting how much traffic is delivered over the 6rd
 connection (if possible), the operator can avoid costly and complex
 scaling of the relay infrastructure.

5.2.1. 6rd Deployment Considerations

 Deploying 6rd can greatly speed up an operator's ability to support
 IPv6 to the subscriber network if native IPv6 connectivity cannot be
 supplied.  The speed at which 6rd can be deployed is highlighted in
 [RFC5569].
 The first core consideration is deployment models.  6rd requires the
 CPE (6rd client) to send traffic to a 6rd relay.  These relays can
 share a common anycast address or can use unique addresses.  Using an
 anycast model, the operator can deploy all the 6rd relays using the
 same IPv4 interior service address.  As the load increases on the
 deployed relays, the operator can deploy more relays into the
 network.  The one drawback is that it may be difficult to manage the
 traffic volume among additional relays, since all 6rd traffic will
 find the nearest (in terms of IGP cost) relay.  The use of multiple
 relay addresses can help provide more control but has the
 disadvantage of being more complex to provision.  Subsets of CPEs

Kuarsingh & Howard Informational [Page 17] RFC 6782 Wireline Incremental IPv6 November 2012

 across the network will require and contain different relay
 information.  An alternative approach is to use a hybrid model using
 multiple anycast service IP addresses for clusters of 6rd relays,
 should the operator anticipate massive scaling of the environment.
 Thus, the operator has multiple vectors by which to scale the
 service.
                                            +--------+
                                            |        |
                              IPv4 Addr.X   |  6rd   |
                                   - - - >  | Relay  |
             +-----------+        /         |        |
             | Client A  | <- - -           +--------+
             +-----------+
                           Separate IPv4 Service Addresses
             +-----------+
             | Client B  | < - -            +--------+
             +-----------+       \          |        |
                                   - - - >  |  6rd   |
                              IPv4 Addr.Y   | Relay  |
                                            |        |
                                            +--------+
           Figure 2: 6rd Multiple IPv4 Service Address Model
                                          +--------+
                                          |        |
                            IPv4 Addr.X   |  6rd   |
                                 - - - >  | Relay  |
           +-----------+        /         |        |
           | Client A  |- - - -           +--------+
           +-----------+
                     Common (Anycast) IPv4 Service Addresses
           +-----------+
           | Client B  | - - -            +--------+
           +-----------+       \          |        |
                                 - - - >  |  6rd   |
                            IPv4 Addr.X   | Relay  |
                                          |        |
                                          +--------+
           Figure 3: 6rd Anycast IPv4 Service Address Model
 Provisioning of the 6rd endpoints is affected by the deployment model
 chosen (i.e., anycast vs. specific service IP addresses).  Using
 multiple IP addresses may require more planning and management, as
 subscriber equipment will have different sets of data to be

Kuarsingh & Howard Informational [Page 18] RFC 6782 Wireline Incremental IPv6 November 2012

 provisioned into the devices.  The operator may use DHCPv4, manual
 provisioning, or other mechanisms to provide parameters to subscriber
 equipment.
 If the operator manages the CPE, support personnel will need tools
 able to report the status of the 6rd tunnel.  Usage information can
 be collected on the operator edge, but if source/destination flow
 details are required, data must be collected after the 6rd relay (the
 IPv6 side of the connection).
 6rd [RFC5969], like any tunneling option, is subject to a reduced
 MTU, so operators need to plan to manage this type of environment.
     +---------+  IPv4 Encapsulation  +------------+
     |         +- - - - - - - - - - - +            |
     |   6rd   +----------------------+     6rd    +------------
     |         |   IPv6 Packet        |    Relay   | IPv6 Packet
     | Client  +----------------------+            +------------
     |         +- - - - - - - - - - - +            |      ^
     +---------+  ^                   +------------+      |
                  |                                       |
                  |                                       |
           IPv4 (Tools/Mgmt)                     IPv6 Flow Analysis
                Figure 4: 6rd Tools and Flow Management

5.3. Phase 2 - Native Dual Stack

 Either as a follow-up phase to "tunneled IPv6" or as an initial step,
 the operator may deploy native IPv6 down to the CPEs.  This phase
 would then allow both IPv6 and IPv4 to be natively accessed by the
 subscriber home network without translation or tunneling.  The native
 Dual Stack phase can be rolled out across the network while the
 tunneled IPv6 service remains operational, if used.  As areas begin
 to support native IPv6, subscriber home equipment will generally
 prefer using the IPv6 addresses derived from the delegated IPv6
 prefix versus tunneling options as defined in [RFC6724], such as 6to4
 and Teredo.  Specific care is needed when moving to native Dual Stack
 from 6rd, as documented in [6rd-SUNSETTING].
 Native Dual Stack is the best option at this point in the transition
 and should be sought as soon as possible.  During this phase, the
 operator can confidently move both internal and external services to
 IPv6.  Since there are no translation devices needed for this mode of
 operation, it transports both protocols (IPv6 and IPv4) efficiently
 within the network.

Kuarsingh & Howard Informational [Page 19] RFC 6782 Wireline Incremental IPv6 November 2012

5.3.1. Native Dual Stack Deployment Considerations

 Native Dual Stack is a very desirable option for the IPv6 transition,
 if feasible.  The operator must enable IPv6 on the network core and
 peering edge before attempting to turn on native IPv6 services.
 Additionally, provisioning and support systems such as DHCPv6, DNS,
 and other functions that support the subscriber's IPv6 Internet
 connection need to be in place.
 The operator must treat IPv6 connectivity with the same operational
 importance as IPv4.  A poor IPv6 service may be worse than not
 offering an IPv6 service at all, as it will negatively impact the
 subscriber's Internet experience.  This may cause users or support
 personnel to disable IPv6, limiting the subscriber from the benefits
 of IPv6 connectivity as network performance improves.  New code and
 IPv6 functionality may cause instability at first.  The operator will
 need to monitor, troubleshoot, and resolve issues promptly.
 Prefix assignment and routing are new for common residential
 services.  Prefix assignment is straightforward (DHCPv6 using
 Identity Associations for Prefix Delegation (IA_PDs)), but
 installation and propagation of routing information for the prefix,
 especially during access layer instability, are often poorly
 understood.  The operator should develop processes for renumbering
 subscribers who move to new access nodes.
 Operators need to keep track of the dynamically assigned IPv4 address
 along with the IPv6 address and prefix.  Any additional dynamic
 elements, such as auto-generated host names, need to be considered
 and planned for.

5.4. Intermediate Phase for CGN

 Acquiring more IPv4 addresses is already challenging, if not
 impossible; therefore, address sharing may be required on the IPv4
 path of a Dual Stack deployment.  The operator may have a preference
 to move directly to a transition technology such as DS-Lite [RFC6333]
 or may use Dual Stack with CGN/NAT444 to facilitate IPv4 connections.
 CGN/NAT444 requires IPv4 addressing between the subscriber premises
 equipment and the operator's translator; this may be facilitated by
 shared addresses [RFC6598], private addresses [RFC1918], or another
 address space.  CGN/NAT444 is only recommended to be used alongside

Kuarsingh & Howard Informational [Page 20] RFC 6782 Wireline Incremental IPv6 November 2012

 IPv6 in a Dual Stack deployment and not on its own.  Figure 5
 provides a comparative view of a traditional IPv4 path versus one
 that uses CGN/NAT444.
                                     +--------+         -----
                                     |        |       /       \
                           IPv4 Flow |  CGN   |      |         |
                              - - -> +        + < -> |         |
        +---------+         /        |        |      |         |
        |   CPE   | <- - - /         +--------+      |  IPv4   |
        |---------+                                  |   Net   |
                                                     |         |
        +---------+         IPv4 Flow                |         |
        |   CPE   | <- - - - - - - - - - - - - - - > |         |
        |---------+                                   \       /
                                                        -----
                   Figure 5: Overlay CGN Deployment
 In the case of native Dual Stack, CGN/NAT444 can be used to assist in
 extending connectivity for the IPv4 path while the IPv6 path remains
 native.  For endpoints operating in an IPv6+CGN/NAT444 model, the
 native IPv6 path is available for higher-quality connectivity,
 helping host operation over the network.  At the same time, the CGN
 path may offer less than optimal performance.  These points are also
 true for DS-Lite.
                                     +--------+         -----
                                     |        |       /       \
                           IPv4 Flow |  CGN   |      |  IPv4   |
                              - - -> +        + < -> |   Net   |
        +---------+         /        |        |       \       /
        |         | <- - - /         +--------+        -------
        |   Dual  |
        |  Stack  |                                     -----
        |   CPE   |         IPv6 Flow                 / IPv6  \
        |         | <- - - - - - - - - - - - - - - > |   Net   |
        |---------+                                   \       /
                                                        -----
                     Figure 6: Dual Stack with CGN
 CGN/NAT444 deployments may make use of a number of address options,
 which include [RFC1918] or Shared Address Space [RFC6598].  It is
 also possible that operators may use part of their own Regional
 Internet Registry (RIR) assigned address space for CGN zone
 addressing if [RFC1918] addresses pose technical challenges in their

Kuarsingh & Howard Informational [Page 21] RFC 6782 Wireline Incremental IPv6 November 2012

 networks.  It is not recommended that operators use 'squat space', as
 it may pose additional challenges with filtering and policy control
 [RFC6598].

5.4.1. CGN Deployment Considerations

 CGN is often considered undesirable by operators but is required in
 many cases.  An operator who needs to deploy CGN capabilities should
 consider the impacts of the function on the network.  CGN is often
 deployed in addition to running IPv4 services and should not
 negatively impact the already working native IPv4 service.  CGNs will
 be needed on a small scale at first and will grow to meet the demands
 based on traffic and connection dynamics of the subscriber, content,
 and network peers.
 The operator may want to deploy CGNs more centrally at first and then
 scale the system as needed.  This approach can help conserve the
 costs of the system, limiting the deployed base and scaling it based
 on actual traffic demand.  The operator should use a deployment model
 and architecture that allow the system to scale as needed.
                                     +--------+         -----
                                     |        |       /       \
                                     |  CGN   |      |         |
                              - - -> +        + < -> |         |
        +---------+         /        |        |      |         |
        |   CPE   | <- - - /         +--------+      |  IPv4   |
        |         |                      ^           |         |
        |---------+                      |           |   Net   |
                         +--------+    Centralized   |         |
        +---------+      |        |       CGN        |         |
        |         |      |  CGN   |                  |         |
        |   CPE   | <- > +        + <- - - - - - - > |         |
        |---------+      |        |                   \       /
                         +--------+                     -----
                             ^
                             |
                         Distributed CGN
         Figure 7: CGN Deployment: Centralized vs. Distributed
 The operator may be required to log translation information
 [CGN-REQS].  This logging may require significant investment in
 external systems that ingest, aggregate, and report such information
 [DETERMINISTIC-CGN].

Kuarsingh & Howard Informational [Page 22] RFC 6782 Wireline Incremental IPv6 November 2012

 Since CGN has noticeable impacts on certain applications
 [NAT444-IMPACTS], operators may deploy CGN only for those subscribers
 who may be less affected by CGN (if possible).

5.5. Phase 3 - IPv6-Only

 Once native IPv6 is widely deployed in the network and well supported
 by tools, staff, and processes, an operator may consider supporting
 only IPv6 to all or some subscriber endpoints.  During this final
 phase, IPv4 connectivity may or may not need to be supported,
 depending on the conditions of the network, subscriber demand, and
 legacy device requirements.  If legacy IPv4 connectivity is still
 demanded (e.g., for older nodes), DS-Lite [RFC6333] may be used to
 tunnel the traffic.  If IPv4 connectivity is not required but access
 to legacy IPv4 content is, then NAT64 [RFC6144] [RFC6146] can be
 used.

5.5.1. DS-Lite

 DS-Lite allows continued access for the IPv4 subscriber base using
 address sharing for IPv4 Internet connectivity but with only a single
 layer of translation, as compared to CGN/NAT444.  This mode of
 operation also removes the need to directly supply subscriber
 endpoints with an IPv4 address, potentially simplifying the
 connectivity to the customer (single address family) and supporting
 IPv6-only addressing to the CPE.
 The operator can also move Dual Stack endpoints to DS-Lite
 retroactively to help optimize the IPv4 address-sharing deployment by
 removing the IPv4 address assignment and routing component.  To
 minimize traffic needing translation, the operator should have
 already moved most content to IPv6 before the IPv6-only phase is
 implemented.
                                      +--------+      -----
                                      |        |    /       \
                      Encap IPv4 Flow |  AFTR  |   |  IPv4   |
                               -------+        +---+   Net   |
         +---------+         /        |        |    \       /
         |         |        /         +--------+      -----
         | DS-Lite +-------                           -----
         |         |                                /       \
         |  Client |         IPv6 Flow             |  IPv6   |
         |         +-------------------------------|   Net   |
         |         |                                \       /
         +---------+                                  -----
                     Figure 8: DS-Lite Basic Model

Kuarsingh & Howard Informational [Page 23] RFC 6782 Wireline Incremental IPv6 November 2012

 If the operator had previously decided to enable a CGN/NAT444
 deployment, it may be able to co-locate the AFTR and CGN/NAT444
 processing functions within a common network location to simplify
 capacity management and the engineering of flows.  This case may be
 evident in a later transition stage, when an operator chooses to
 optimize its network and IPv6-only operation is feasible.

5.5.2. DS-Lite Deployment Considerations

 The same deployment considerations associated with native IPv6
 deployments apply to DS-Lite and NAT64.  IPv4 will now be dependent
 on IPv6 service quality, so the IPv6 network and services must be
 running well to ensure a quality experience for the end subscriber.
 Tools and processes will be needed to manage the encapsulated IPv4
 service.  If flow analysis is required for IPv4 traffic, this may be
 enabled at a point beyond the AFTR (after decapsulation) or where
 DS-Lite-aware equipment is used to process traffic midstream.
   +---------+  IPv6 Encapsulation  +------------+
   |         + - - - - - - - - - - -+            |
   |  AFTR   +----------------------+    AFTR    +------------
   |         |   IPv4 Packet        |            | IPv4 Packet
   | Client  +----------------------+            +------------
   |         + - - - - - - - - - - -+            |      ^
   +---------+  ^               ^   +------------+      |
                |               |                       |
                |               |                       |
         IPv6 (Tools/Mgmt)      |           IPv4 Packet Flow Analysis
                                |
           Midstream IPv4 Packet Flow Analysis (Encapsulation Aware)
               Figure 9: DS-Lite Tools and Flow Analysis
 DS-Lite [RFC6333] also requires client support on the subscriber
 premises device.  The operator must clearly articulate to vendors
 which technologies will be used at which points, how they interact
 with each other at the CPE, and how they will be provisioned.  As an
 example, an operator may use 6rd in the outset of the transition,
 then move to native Dual Stack followed by DS-Lite.
 DS-Lite [RFC6333], like any tunneling option, is subject to a reduced
 MTU, so operators need to plan to manage this type of environment.
 Additional considerations for DS-Lite deployments can be found in
 [DSLITE-DEPLOYMENT].

Kuarsingh & Howard Informational [Page 24] RFC 6782 Wireline Incremental IPv6 November 2012

5.5.3. NAT64 Deployment Considerations

 The deployment of NAT64 assumes that the network assigns an IPv6
 address to a network endpoint that is translated to an IPv4 address
 to provide connectivity to IPv4 Internet services and content.
 Experiments such as the one described in [RFC6586] highlight issues
 related to IPv6-only deployments due to legacy IPv4 APIs and IPv4
 literals.  Many of these issues will be resolved by the eventual
 removal of this undesirable legacy behavior.  Operational deployment
 models, considerations, and experiences related to NAT64 have been
 documented in [NAT64-EXPERIENCE].
                                      +--------+      -----
                                      |        |    /       \
                            IPv6 Flow | NAT64  |   |  IPv4   |
                               -------+ DNS64  +---+   Net   |
         +---------+         /        |        |    \       /
         |         |        /         +--------+      -----
         |  IPv6   +-------                           -----
         |         |                                /       \
         |  Only   |         IPv6 Flow             |  IPv6   |
         |         +-------------------------------|   Net   |
         |         |                                \       /
         +---------+                                  -----
                  Figure 10: NAT64/DNS64 Basic Model
 To navigate some of the limitations of NAT64 when dealing with legacy
 IPv4 applications, the operator may choose to implement 464XLAT
 [464XLAT] if possible.  As support for IPv6 on subscriber equipment
 and content increases, the efficiency of NAT64 increases by reducing
 the need to translate traffic.  NAT64 deployments would see an
 overall decline in translator usage as more traffic is promoted to
 IPv6-to-IPv6 native communication.  NAT64 may play an important part
 in an operator's late-stage transition, as it removes the need to
 support IPv4 on the access network and provides a solid go-forward
 networking model.
 It should be noted, as with any technology that utilizes address
 sharing, that the IPv4 public pool sizes (IPv4 transport addresses
 per [RFC6146]) can pose limits to IPv4 server connectivity for the
 subscriber base.  Operators should be aware that some IPv4 growth in
 the near term is possible, so IPv4 translation pools need to be
 monitored.

Kuarsingh & Howard Informational [Page 25] RFC 6782 Wireline Incremental IPv6 November 2012

6. Security Considerations

 Operators should review the documentation related to the technologies
 selected for IPv6 transition.  In those reviews, operators should
 understand what security considerations are applicable to the chosen
 technologies.  As an example, [RFC6169] should be reviewed to
 understand security considerations related to tunneling technologies.

7. Acknowledgements

 Special thanks to Wes George, Chris Donley, Christian Jacquenet, and
 John Brzozowski for their extensive review and comments.
 Thanks to the following people for their textual contributions,
 guidance, and comments: Jason Weil, Gang Chen, Nik Lavorato, John
 Cianfarani, Chris Donley, Tina TSOU, Fred Baker, and Randy Bush.

8. References

8.1. Normative References

 [RFC6180]  Arkko, J. and F. Baker, "Guidelines for Using IPv6
            Transition Mechanisms during IPv6 Deployment", RFC 6180,
            May 2011.

8.2. Informative References

 [464XLAT]  Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
            Combination of Stateful and Stateless Translation", Work
            in Progress, September 2012.
 [6rd-SUNSETTING]
            Townsley, W. and A. Cassen, "6rd Sunsetting", Work
            in Progress, November 2011.
 [CGN-REQS]
            Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
            A., and H. Ashida, "Common requirements for Carrier Grade
            NATs (CGNs)", Work in Progress, August 2012.
 [COMCAST-IPv6-EXPERIENCES]
            Brzozowski, J. and C. Griffiths, "Comcast IPv6 Trial/
            Deployment Experiences", Work in Progress, October 2011.

Kuarsingh & Howard Informational [Page 26] RFC 6782 Wireline Incremental IPv6 November 2012

 [DETERMINISTIC-CGN]
            Donley, C., Grundemann, C., Sarawat, V., and K.
            Sundaresan, "Deterministic Address Mapping to Reduce
            Logging in Carrier Grade NAT Deployments", Work
            in Progress, July 2012.
 [DSLITE-DEPLOYMENT]
            Lee, Y., Maglione, R., Williams, C., Jacquenet, C., and M.
            Boucadair, "Deployment Considerations for Dual-Stack
            Lite", Work in Progress, August 2012.
 [IPv6-CE-RTR-REQS]
            Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
            Requirements for IPv6 Customer Edge Routers", Work
            in Progress, October 2012.
 [IPv6-DESIGN]
            Matthews, P., "Design Guidelines for IPv6 Networks", Work
            in Progress, October 2012.
 [IPv6-ICP-ASP-GUIDANCE]
            Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet
            Content and Application Service Providers", Work
            in Progress, September 2012.
 [NAT444-IMPACTS]
            Donley, C., Ed., Howard, L., Kuarsingh, V., Berg, J., and
            J. Doshi, "Assessing the Impact of Carrier-Grade NAT on
            Network Applications", Work in Progress, October 2012.
 [NAT64-EXPERIENCE]
            Chen, G., Cao, Z., Byrne, C., Xie, C., and D. Binet,
            "NAT64 Operational Experiences", Work in Progress,
            August 2012.
 [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
            E. Lear, "Address Allocation for Private Internets",
            BCP 5, RFC 1918, February 1996.
 [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
            (IPv6) Specification", RFC 2460, December 1998.
 [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
            via IPv4 Clouds", RFC 3056, February 2001.
 [RFC3068]  Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
            RFC 3068, June 2001.

Kuarsingh & Howard Informational [Page 27] RFC 6782 Wireline Incremental IPv6 November 2012

 [RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
            Network Address Translations (NATs)", RFC 4380,
            February 2006.
 [RFC4942]  Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/
            Co-existence Security Considerations", RFC 4942,
            September 2007.
 [RFC5569]  Despres, R., "IPv6 Rapid Deployment on IPv4
            Infrastructures (6rd)", RFC 5569, January 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.
 [RFC6144]  Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
            IPv4/IPv6 Translation", RFC 6144, April 2011.
 [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
            NAT64: Network Address and Protocol Translation from IPv6
            Clients to IPv4 Servers", RFC 6146, April 2011.
 [RFC6169]  Krishnan, S., Thaler, D., and J. Hoagland, "Security
            Concerns with IP Tunneling", RFC 6169, April 2011.
 [RFC6264]  Jiang, S., Guo, D., and B. Carpenter, "An Incremental
            Carrier-Grade NAT (CGN) for IPv6 Transition", RFC 6264,
            June 2011.
 [RFC6269]  Ford, M., Boucadair, M., Durand, A., Levis, P., and P.
            Roberts, "Issues with IP Address Sharing", RFC 6269,
            June 2011.
 [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
            Stack Lite Broadband Deployments Following IPv4
            Exhaustion", RFC 6333, August 2011.
 [RFC6343]  Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
            RFC 6343, August 2011.
 [RFC6540]  George, W., Donley, C., Liljenstolpe, C., and L. Howard,
            "IPv6 Support Required for All IP-Capable Nodes", BCP 177,
            RFC 6540, April 2012.

Kuarsingh & Howard Informational [Page 28] RFC 6782 Wireline Incremental IPv6 November 2012

 [RFC6586]  Arkko, J. and A. Keranen, "Experiences from an IPv6-Only
            Network", RFC 6586, April 2012.
 [RFC6598]  Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and
            M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address
            Space", BCP 153, RFC 6598, April 2012.
 [RFC6724]  Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
            "Default Address Selection for Internet Protocol Version 6
            (IPv6)", RFC 6724, September 2012.
 [RFC6732]  Kuarsingh, V., Lee, Y., and O. Vautrin, "6to4 Provider
            Managed Tunnels", RFC 6732, September 2012.

Authors' Addresses

 Victor Kuarsingh (editor)
 Rogers Communications
 8200 Dixie Road
 Brampton, Ontario  L6T 0C1
 Canada
 EMail: victor.kuarsingh@gmail.com
 URI:   http://www.rogers.com
 Lee Howard
 Time Warner Cable
 13820 Sunrise Valley Drive
 Herndon, VA  20171
 US
 EMail: lee.howard@twcable.com
 URI:   http://www.timewarnercable.com

Kuarsingh & Howard Informational [Page 29]

/data/webs/external/dokuwiki/data/pages/rfc/rfc6782.txt · Last modified: 2012/11/07 15:51 (external edit)