draft-ietf-v6ops-wireline-incremental-ipv6-02.txt   draft-ietf-v6ops-wireline-incremental-ipv6-03.txt 
v6ops V. Kuarsingh, Ed. v6ops V. Kuarsingh, Ed.
Internet-Draft Rogers Communications Internet-Draft Rogers Communications
Intended status: Informational L. Howard Intended status: Informational L. Howard
Expires: November 10, 2012 Time Warner Cable Expires: November 24, 2012 Time Warner Cable
May 9, 2012 May 23, 2012
Wireline Incremental IPv6 Wireline Incremental IPv6
draft-ietf-v6ops-wireline-incremental-ipv6-02 draft-ietf-v6ops-wireline-incremental-ipv6-03
Abstract Abstract
Operators worldwide are in various stages of preparing for, or Operators worldwide are in various stages of preparing for, or
deploying IPv6 into their networks. The operators often face deploying IPv6 into their networks. The operators often face
difficult challenges related to both IPv6 introduction along with difficult challenges related to both IPv6 introduction along with
those related to IPv4 run out. Operators will need to meet the those related to IPv4 run out. Operators will need to meet the
simultaneous needs of IPv6 connectivity and continue support for IPv4 simultaneous needs of IPv6 connectivity and continue support for IPv4
connectivity for legacy devices with a stagnant supply of IPv4 connectivity for legacy devices with a stagnant supply of IPv4
addresses. The IPv6 transition will take most networks from an IPv4- addresses. The IPv6 transition will take most networks from an IPv4-
only environment to an IPv6 dominant environment with long transition only environment to an IPv6 dominant environment with long transition
period varying by operator. This document helps provide a framework period varying by operator. This document helps provide a framework
for Wireline providers who are faced with the challenges of for wireline providers who are faced with the challenges of
introducing IPv6 along with meeting the legacy needs of IPv4 introducing IPv6 along with meeting the legacy needs of IPv4
connectivity utilizing well defined and commercially available IPv6 connectivity utilizing well defined and commercially available IPv6
transition technologies. transition technologies.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 10, 2012. This Internet-Draft will expire on November 24, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 13 skipping to change at page 3, line 13
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Operator Assumptions . . . . . . . . . . . . . . . . . . . . . 4 2. Operator Assumptions . . . . . . . . . . . . . . . . . . . . . 4
3. Reasons and Considerations for a Phased Approach . . . . . . . 5 3. Reasons and Considerations for a Phased Approach . . . . . . . 5
3.1. Relevance of IPv6 and IPv4 . . . . . . . . . . . . . . . . 6 3.1. Relevance of IPv6 and IPv4 . . . . . . . . . . . . . . . . 6
3.2. IPv4 Resource Challenges . . . . . . . . . . . . . . . . . 6 3.2. IPv4 Resource Challenges . . . . . . . . . . . . . . . . . 6
3.3. IPv6 Introduction and Operational Maturity . . . . . . . . 7 3.3. IPv6 Introduction and Operational Maturity . . . . . . . . 7
3.4. Service Management . . . . . . . . . . . . . . . . . . . . 7 3.4. Service Management . . . . . . . . . . . . . . . . . . . . 8
3.5. Sub-Optimal Operation of Transition Technologies . . . . . 8 3.5. Sub-Optimal Operation of Transition Technologies . . . . . 8
3.6. Future IPv6 Network . . . . . . . . . . . . . . . . . . . 9 3.6. Future IPv6 Network . . . . . . . . . . . . . . . . . . . 9
4. IPv6 Transition Technology Analysis . . . . . . . . . . . . . 9 4. IPv6 Transition Technology Analysis . . . . . . . . . . . . . 9
4.1. Automatic Tunnelling using 6to4 and Teredo . . . . . . . . 9 4.1. Automatic Tunneling using 6to4 and Teredo . . . . . . . . 9
4.2. Carrier Grade NAT (NAT444) . . . . . . . . . . . . . . . . 10 4.2. Carrier Grade NAT (NAT444) . . . . . . . . . . . . . . . . 10
4.3. 6RD . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.3. 6RD . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Native Dual Stack . . . . . . . . . . . . . . . . . . . . 11 4.4. Native Dual Stack . . . . . . . . . . . . . . . . . . . . 11
4.5. DS-Lite . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.5. DS-Lite . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.6. NAT64 . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.6. NAT64 . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. IPv6 Transition Phases . . . . . . . . . . . . . . . . . . . . 12 5. IPv6 Transition Phases . . . . . . . . . . . . . . . . . . . . 12
5.1. Phase 0 - Foundation . . . . . . . . . . . . . . . . . . . 13 5.1. Phase 0 - Foundation . . . . . . . . . . . . . . . . . . . 13
5.1.1. Phase 0 - Foundation: Training . . . . . . . . . . . . 13 5.1.1. Phase 0 - Foundation: Training . . . . . . . . . . . . 13
5.1.2. Phase 0 - Foundation: Routing . . . . . . . . . . . . 13 5.1.2. Phase 0 - Foundation: Routing . . . . . . . . . . . . 13
5.1.3. Phase 0 - Foundation: Network Policy and Security . . 14 5.1.3. Phase 0 - Foundation: Network Policy and Security . . 14
5.1.4. Phase 0 - Foundation: Transition Architecture . . . . 14 5.1.4. Phase 0 - Foundation: Transition Architecture . . . . 14
5.1.5. Phase 0- Foundation: Tools and Management . . . . . . 14 5.1.5. Phase 0- Foundation: Tools and Management . . . . . . 15
5.2. Phase 1 - Tunnelled IPv6 . . . . . . . . . . . . . . . . . 15 5.2. Phase 1 - Tunneled IPv6 . . . . . . . . . . . . . . . . . 15
5.2.1. 6RD Deployment Considerations . . . . . . . . . . . . 16 5.2.1. 6RD Deployment Considerations . . . . . . . . . . . . 16
5.3. Phase 2: Native Dual Stack . . . . . . . . . . . . . . . . 18 5.3. Phase 2: Native Dual Stack . . . . . . . . . . . . . . . . 18
5.3.1. Native Dual Stack Deployment Considerations . . . . . 19 5.3.1. Native Dual Stack Deployment Considerations . . . . . 19
5.4. Intermediate Phase for CGN . . . . . . . . . . . . . . . . 19 5.4. Intermediate Phase for CGN . . . . . . . . . . . . . . . . 19
5.4.1. CGN Deployment Considerations . . . . . . . . . . . . 21 5.4.1. CGN Deployment Considerations . . . . . . . . . . . . 21
5.5. Phase 3 - IPv6-Only . . . . . . . . . . . . . . . . . . . 22 5.5. Phase 3 - IPv6-Only . . . . . . . . . . . . . . . . . . . 22
5.5.1. DS-Lite Deployment Considerations . . . . . . . . . . 23 5.5.1. DS-Lite Deployment Considerations . . . . . . . . . . 23
5.5.2. NAT64 Deployment Considerations . . . . . . . . . . . 23 5.5.2. NAT64 Deployment Considerations . . . . . . . . . . . 24
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
7. Security Considerations . . . . . . . . . . . . . . . . . . . 24 7. Security Considerations . . . . . . . . . . . . . . . . . . . 24
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1. Normative References . . . . . . . . . . . . . . . . . . . 24 9.1. Normative References . . . . . . . . . . . . . . . . . . . 25
9.2. Informative References . . . . . . . . . . . . . . . . . . 24 9.2. Informative References . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
This draft sets out to help Wireline operators in planning their IPv6 This draft sets out to help wireline operators in planning their IPv6
deployments while ensuring continued support for IPv6-incapable deployments while ensuring continued support for IPv6-incapable
consumer devices and applications. We will identify which consumer devices and applications. This document identifies which
technologies can be used incrementally to transition from IPv4-only technologies can be used incrementally to transition from IPv4-only
to an IPv6 dominant environment with support for dual stack to an IPv6 dominant environment with support for dual stack
operation. The end state goal for most operators will be IPv6-only, operation. The end state goal for most operators will be IPv6-only,
but the path to this final state will heavily depend on the amount of but the path to this final state will heavily depend on the amount of
legacy equipment resident in end networks and management of long tail legacy equipment resident in end networks and management of long tail
IPv4-only content. Although no single plan will work for all IPv4-only content. Although no single plan will work for all
operators, options listed herein provide a baseline which can be operators, options listed herein provide a baseline which can be
included in many plans. included in many plans.
This draft is intended for Wireline environments which include Cable, This draft is intended for wireline environments which include Cable,
DSL and/or Fibre as the access method to the end consumer. This DSL and/or fiber as the access method to the end consumer. This
document attempts to follow the principles laid out in [RFC6180] document attempts to follow the principles laid out in [RFC6180]
which provides guidance on using IPv6 transition mechanisms. This which provides guidance on using IPv6 transition mechanisms. This
document will focus on technologies which enable and mature IPv6 document will focus on technologies which enable and mature IPv6
within the operator's network, but will also include a cursory view within the operator's network, but will also include a cursory view
of IPv4 connectivity continuance. The focal transition technologies of IPv4 connectivity continuance. The focal transition technologies
include 6RD [RFC5969], DS-Lite [RFC6333], NAT64 and Dual Stack include 6RD [RFC5969], DS-Lite [RFC6333], NAT64 [RFC6146] and Dual
operation which may also include a CGN/NAT444 deployment. Focus on Stack operation which may also include a CGN/NAT444 deployment.
these technologies is based on their inclusion in many off-the-shelf Focus on these technologies is based on their inclusion in many off-
CPEs and availability in commercially available equipment. the-shelf CPEs and availability in commercially available equipment.
2. Operator Assumptions 2. Operator Assumptions
For the purposes of this document, the authors assume: For the purposes of this document, the authors assume:
- The operator is considering deploying IPv6 or is in progress in - The operator is considering deploying IPv6 or is in progress in
deploying IPv6 deploying IPv6
- The operator has a legacy IPv4 customer base which will continue - The operator has a legacy IPv4 subscriber base that will
to exist for a period of time continue to exist for a period of time
- The operator will want to minimize the level of disruption to - The operator will want to minimize the level of disruption to
the existing and new customers by minimizing the number of the existing and new subscribers by minimizing the number of
technologies and functions that are needed to mediate any given technologies and functions that are needed to mediate any given
set of customer flows (overall preference for Native IP flows) set of subscribers flows (overall preference for Native IP flows)
- The operator is able to run Dual Stack on their own core network - The operator is able to run Dual Stack on their own core network
and is able to transition their own services to support IPv6 and is able to transition their own services to support IPv6
Based on these assumptions, an operator will want to utilize Based on these assumptions, an operator will want to utilize
technologies which minimize the need to tunnel, translate or mediate technologies that minimize the need to tunnel, translate or mediate
flows to help optimize traffic flow and lower the cost impacts of flows to help optimize traffic flow and lower the cost impacts of
transition technologies. Transition technology selections should be transition technologies. Transition technology selections should be
made to mediate the non-dominant IP family flows and allow native made to mediate the non-dominant IP family flows and allow native
routing (IPv4 and/or IPv6) to forward the dominant traffic whenever routing (IPv4 and/or IPv6) to forward the dominant traffic whenever
possible. This allows the operator to minimize the cost of IPv6 possible. This allows the operator to minimize the cost of IPv6
transition technologies by minimizing the transition technology transition technologies by minimizing the transition technology
deployment size. deployment size.
An operator may also choose to prefer more IPv6 focused models where An operator may also choose to prefer more IPv6 focused models where
the use of transition technologies are based on an effort to enable the use of transition technologies are based on an effort to enable
IPv6 at the base layer as soon as possible. Operators may want to IPv6 at the base layer as soon as possible. Some operators may want
promote IPv6 early on in the deployment and have IPv6 traffic perform to promote IPv6 early on in the deployment and have IPv6 traffic
optimally from the outset. This desire would need to be weighed perform optimally from the outset. This desire would need to be
against the cost and support impacts of such an choice. 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 3. Reasons and Considerations for a Phased Approach
When faced with the challenges described in the Introduction, When faced with the challenges described in the introduction,
operators may need to consider a phased approach when adding IPv6 to operators may need to consider a phased approach when adding IPv6 to
an existing customer base. A phased approach allows the operator to an existing subscriber base. A phased approach allows the operator
add in IPv6 while not ignoring legacy IPv4 connection requirements. to add in IPv6 while not ignoring legacy IPv4 connection
Some of the main challenges which the operator will face include: requirements. Some of the main challenges the operator will face
include:
- IPv4 exhaustion may occur long before all traffic is able to be - IPv4 exhaustion may occur long before all traffic is able to be
delivered over IPv6, necessitating IPv4 address sharing delivered over IPv6, necessitating IPv4 address sharing
- IPv6 will pose operational challenges since some of the software - IPv6 will pose operational challenges since some of the software
is quite new and has had short run time in large production is quite new and has had short run time in large production
environments and organizations are also not acclimatized to environments and organizations are also not acclimatized to
supporting IPv6 as a service supporting IPv6 as a service
- Many access network devices or customer controlled CPEs may not - Many access network devices or subscriber controlled CPEs may
support native IPv6 operation for a period of time not support native IPv6 operation for a period of time. [RFC6540]
should remedy the situation over time as the document requires
IPv6 support for all IP-capable nodes
- Connectivity modes will move from IPv4-only to Dual Stack in the - Connectivity modes will move from IPv4-only to Dual Stack in the
home, changing functional behaviours in the consumer network home, changing functional behaviors in the consumer network and
increasing support requirements for the operator increasing support requirements for the operator
These challenges will occur over a period of time which means the These challenges will occur over a period of time, which means that
operator's plans need to address the ever changing requirements of the operator's plans need to address the ever changing requirements
the network and customer demand. The following few sections of the network and subscriber demand. Although phases will be
highlight some of the key reasons why a phased approach to IPv6 presented in this document, not all operators may need to enable each
transition may be warranted and desired. discrete phase. It is possible that characteristics in individual
networks may allow certain operators to skip or jump to various
Although phases will be presented in this document, not all operators phases.
may need to enable each desecrate 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 3.1. Relevance of IPv6 and IPv4
The delivery of IPv6 connectivity should be the primary goal for The delivery of high-quality unencumbered Internet service should be
operators. Even though the operator may be focused on IPv6 delivery, the primary goal for operators. It is recognized that with the
they should be aware that both IPv4 and IPv6 will play a role in the imminent exhaustion of IPv4, IPv6 will offer the highest quality of
Internet experience during transition. Many customers use older experience in the long term. Even though the operator may be focused
operating systems and hardware which support IPv4-only operation. on IPv6 delivery, they should be aware that both IPv4 and IPv6 will
Internet customers don't buy IPv4 or IPv6 connections, they buy play a role in the Internet experience during transition. The
Internet connections, which demands the need to support both IPv4 and Internet is made of many interconnecting systems, networks, hardware,
IPv6 for as long at the customer's home network demands such support. software and content sources - all of which will move to IPv6 at
different rates.
The Internet is made of of many interconnecting systems, networks, Many subscribers use older operating systems and hardware which
hardware, software and content sources - all of which will move to support IPv4-only operation. Internet subscribers don't buy IPv4 or
IPv6 at different rates. The Operator's mandate during this time of IPv6 connections; they buy Internet connections, which demands the
transition will be to support connectivity to both IPv6 and IPv4 need to support both IPv4 and IPv6 for as long at the subscriber's
through various technological means. The operator may be able to home network demands such support. The operator may be able to
leverage one or the other protocol to help bridge connectivity, but leverage one or the other protocol to help bridge connectivity on the
the home network will likely demand both IPv4 and IPv6 for some time. operator's network, but the home network will likely demand both IPv4
and IPv6 for some time.
3.2. IPv4 Resource Challenges 3.2. IPv4 Resource Challenges
Since connectivity to IPv4-only endpoints and/or content will remain Since connectivity to IPv4-only endpoints and/or content will remain
common, IPv4 resource challenges are of key concern to operators. common, IPv4 resource challenges are of key concern to operators.
The lack of new IPv4 addressees for additional devices means that The lack of new IPv4 addresses for additional devices means that
growth in demand of IPv4 connections in some networks will be meeting the growth in demand of IPv4 connections in some networks
facilitated by address sharing. will require address sharing.
Networks are growing at different rates including those in emerging Networks are growing at different rates including those in emerging
markets and established networks based on the proliferation of markets and established networks based on the proliferation of
Internet based services and devices. IPv4 address constraints will Internet based services and devices. IPv4 address constraints will
likely affect many if not most operators at some point increasing the likely affect many if not most operators at some point, increasing
benefits of IPv6. IPv4 address exhaustion is a consideration when the benefits of IPv6. IPv4 address exhaustion is a consideration
selecting technologies which rely on IPv4 to supply IPv6 services, when selecting technologies which rely on IPv4 to supply IPv6
such as 6RD. Additionally, if native Dual Stack is considered by the services, such as 6RD. Additionally, if native Dual Stack is
operator, challenges related to IPv4 address exhaustion remain a considered by the operator, challenges related to IPv4 address
concern. exhaustion remain a concern.
Some operators may be able to reclaim small amounts IPv4 addresses Some operators may be able to reclaim small amounts IPv4 addresses
through addressing efficiencies in the network, although this will through addressing efficiencies in the network, although this will
have little lasting benefits to the network and not meet longer term have little lasting benefits to the network and not meet longer term
connectivity needs. The lack of new global IPv4 address allocations connectivity needs. The lack of new global IPv4 address allocations
will therefore force operators to support some form of IPv4 address will therefore force operators to support some form of IPv4 address
sharing and may impact technological options for transition once the sharing and may impact technological options for transition once the
operator runs out of new IPv4 addresses for assignment. operator runs out of new IPv4 addresses for assignment.
3.3. IPv6 Introduction and Operational Maturity 3.3. IPv6 Introduction and Operational Maturity
The introduction of IPv6 will require the operationalization of IPv6. The introduction of IPv6 will require new operational practices. The
The IPv4 environment we have today was built over many years and IPv4 environment we have today was built over many years and matured
matured by experience. Although many of these experiences are by experience. Although many of these experiences are transferable
transferable from IPv4 to IPv6, new experience specific to IPv6 will from IPv4 to IPv6, new experience and practices specific to IPv6 will
be needed. be needed.
Engineering and Operational staff will need to develop experience Engineering and Operational staff will need to develop experience
with IPv6. Inexperience may lead to early IPv6 deployment with IPv6. Inexperience may lead to early IPv6 deployment
instability, and Operators should consider this when selecting instability, and operators should consider this when selecting
technologies for initial transition. Operators may not want to technologies for initial transition. Operators may not want to
subject their mature IPv4 service to a "new IPv6" path initially subject their mature IPv4 service to a "new IPv6" path initially
while it may be going through growing pains. DS-Lite [RFC6333] and while it may be going through growing pains. DS-Lite [RFC6333] and
NAT64 are both technologies which requires IPv6 to support NAT64 [RFC6146] are both technologies which requires IPv6 to support
connectivity to IPv4 endpoints or content over an IPv6-only access connectivity to IPv4 endpoints or content over an IPv6-only access
network. network.
Further, some of these transition technologies are new and require Further, some of these transition technologies are new and require
refinement within running code. Deployment experience is required to refinement within running code. Deployment experience is required to
expose bugs and stabilize software in production environments. Many expose bugs and stabilize software in production environments. Many
supporting systems are also under development and have newly supporting systems are also under development and have newly
developed IPv6 functionality including vendor implementations of developed IPv6 functionality including vendor implementations of
DHCPv6, Management Tools, Monitoring Systems, Diagnostic systems, DHCPv6, management tools, monitoring systems, diagnostic systems,
along with other elements. logging, along with other elements.
Although the base technological capabilities exist to enable and run Although the base technological capabilities exist to enable and run
IPv6 in most environments, organizational experience is low. Until IPv6 in most environments, organizational experience is low. Until
such time as each key technical member of an operator's organization such time as each key technical member of an operator's organization
can identify IPv6, understand its relevance to the IP Service can identify IPv6, understand its relevance to the IP service
offering, how it operates and how to troubleshoot it - the deployment offering, how it operates and how to troubleshoot it, the deployment
is maturing. This fact should not incline operators to delay their needs to mature, and may be subject to subscriber-impacting events.
IPv6 deployment, but should drive them to deploy IPv6 sooner to gain This fact should not incline operators to delay their IPv6
the much needed experience before IPv6 is the only viable way to deployment, but should drive them to deploy IPv6 sooner to gain the
connect new hosts to the network. 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 It should also be noted that although many transition technologies
may be new, and some code related to access environments may be new, may be new, and some code related to access environments may be new,
there is a large segment of the networking fabric which has had IPv6 there is a large segment of the networking fabric which has had IPv6
available for a long period of time and has had extended exposure in available for a long period of time and has had extended exposure in
production. Operators may use this to their advantage by first production. Operators may use this to their advantage by first
enabling IPv6 in the core of their network then work outward towards enabling IPv6 in the core of their network then work outward towards
the customer edge. the subscriber edge.
3.4. Service Management 3.4. Service Management
Services are managed within most networks and are often based on the Services are managed within most networks and are often based on the
gleaning and monitoring of IPv4 addresses assigned to endpoints. gleaning and monitoring of IPv4 addresses assigned to endpoints.
Operators will need to address such management tools, troubleshooting Operators will need to address such management tools, troubleshooting
methods and storage facilities (such as databases) to deal with not methods and storage facilities (such as databases) to deal with not
just a new address type containing a 128-bit IPv6 address, but often just a new address type containing a 128-bit IPv6 address [RFC2460],
both IPv4 and IPv6 at the same time. Examination of address type, but often both IPv4 and IPv6 at the same time. Examination of
and recording delegated prefixes along with single address address type, and recording delegated prefixes along with single
assignments, will likely require additional development. address assignments, will likely require additional development.
With any Dual Stack service - whether Native, 6RD based, DS-Lite, With any Dual Stack service - whether Native, 6RD-based, DS-Lite,
NAT64 or otherwise - two address families may need to be managed NAT64 or otherwise - two address families may need to be managed
simultaneously to help provide for the full Internet experience. simultaneously to help provide for the full Internet experience.
This would indicate that IPv6 management is not just a simple add in, This would indicate that IPv6 management is not just a simple add in,
but needs to be well integrated into the service management but needs to be well integrated into the service management
infrastructure. In the early transition phases, it's quite likely infrastructure. In the early transition phases, it's quite likely
that many systems will be missed and that IPv6 services will go un- that many systems will be missed and that IPv6 services will go un-
monitored and impairments undetected. monitored and impairments undetected.
These issues may be of consideration when selecting technologies These issues may be of consideration when selecting technologies that
which require IPv6 as the base protocol to delivery IPv4 require IPv6 as the base protocol to delivery IPv4 connectivity.
connectivity. Instability on the IPv6 service in such a case would Instability on the IPv6 service in such a case would impact IPv4
impact IPv4 services. services.
3.5. Sub-Optimal Operation of Transition Technologies 3.5. Sub-Optimal Operation of Transition Technologies
When contrasting native Dual Stack versus other transition Native delivery of IPv4 and IPv6 provides a solid foundation for
technologies it should be noted that native IP paths are well delivery of Internet services to subscribers since native IP paths
understood and networks are often optimized to send such traffic are well understood and networks are often optimized to send such
efficiently. Transition technologies however, may alter the normal traffic efficiently. Transition technologies however, may alter the
path of traffic removing many network efficiencies built for native normal path of traffic or reduce the path MTU, removing many network
IP flows. Tunnelling and translation devices may not be located on efficiencies built for native IP flows. Tunneling and translation
the most optimal path in line with natural traffic flow (based on devices may not be located on the most optimal path in line with the
route computation) and therefore may increase latency. These paths natural traffic flow (based on route computation) and therefore may
may also add additional points of failure. increase latency. These paths may also add additional points of
failure.
To minimize risk, an operator should use transition technologies for Generally, the operator will want to deliver native IPv6 as soon as
the less dominant address family if possible. During earlier phases possible and utilize transition technologies only when required.
of transition, IPv4 traffic volumes may still be dominant, so Transition technologies may be used to provide continued access to
tunnelling of IPv6 traffic is reasonable. Over time, as IPv6 traffic IPv4 via tunneling and/or translation or may be used to deliver IPv6
volumes will increase, native delivery of IPv6 traffic becomes connectivity. The delivery of Internet or internal services should
advantageous. When IPv4 connectivity demands diminish, translation be considered by the operator, since supplying connections using a
and tunnelling of IPv4 over IPv6 may be acceptable and more optimal. transition technology will reduce the overall performance for the
subscriber.
When IPv6 tunnelling is used, an operator may not want to enable IPv6 When choosing between various transition technologies, operators
for their services, especially high traffic services like high should consider the benefits and drawbacks of each option. Some
quality IP video. Likewise, if CGN is deployed, the operator may technologies like CGN/NAT444 utilize many existing addressing and
wish to promote native IPv6 access for these services. management practices. Other options such as DS-Lite and NAT64 remove
the IPv4 addressing requirement to the subscriber premise device but
require IPv6 to be operational and well supported.
3.6. Future IPv6 Network 3.6. Future IPv6 Network
An operator should also be aware that longer term plans may include An operator should also be aware that longer-term plans may include
IPv6-only operation in all or much of the network. This longer term IPv6-only operation in all or much of the network. The IPv6-only
view may be distant to some, but should be considered when planning operation may be complemented by technologies such as NAT64 for long-
out networks, addressing and services. The needs and costs of tail IPv4 content reach. This longer term view may be distant to
maintaining two IP stacks will eventually become burdensome and some, but should be considered when planning out networks, addressing
simplification will be desirable. The operators should plan for this and services. The needs and costs of maintaining two IP stacks will
state and not make IPv6 inherently dependent on IPv4 as this would eventually become burdensome and simplification will be desirable.
unnecessarily constrain the network. The operators should plan for this state and not make IPv6 inherently
dependent on IPv4 as this would unnecessarily constrain the network.
4. IPv6 Transition Technology Analysis 4. IPv6 Transition Technology Analysis
Operators should understand the main transition technologies for IPv6 Operators should understand the main transition technologies for IPv6
deployment and IPv4 runout. This draft provides a brief description deployment and IPv4 runout. This draft provides a brief description
of some of the mainstream and commercially available options. This of some of the mainstream and commercially available options. This
analysis is focused on the applicability of technologies to deliver analysis is focused on the applicability of technologies to deliver
residential services and less focused on commercial access, Wireless residential services and less focused on commercial access, wireless,
or infrastructure support. or infrastructure support.
The technologies in focus for this document are targeted on those The technologies in focus for this document are targeted on those
commercially available and in deployment. commercially available and in deployment.
4.1. Automatic Tunnelling using 6to4 and Teredo 4.1. Automatic Tunneling using 6to4 and Teredo
Even when operators may not be actively deploying IPv6, automatic Even when operators may not be actively deploying IPv6, automatic
mechanisms exist on customer operating systems and CPE hardware. mechanisms exist on subscriber operating systems and CPE hardware.
Such technologies include 6to4 [RFC3056] which is most commonly used Such technologies include 6to4 [RFC3056], which is most commonly used
with anycast relays [RFC3068]. Teredo [RFC4380] is also used widely with anycast relays [RFC3068]. Teredo [RFC4380] is also used widely
by many Internet hosts. by many Internet hosts.
Documents such as [RFC6343] have been written to help operators Documents such as [RFC6343] have been written to help operators
understand observed problems with 6to4 deployments and provides understand observed problems with 6to4 deployments and provides
guidelines on how to improve it's performance. An Operator may want guidelines on how to improve it's performance. An operator may want
to provide local relays for 6to4 and/or Teredo to help improve the to provide local relays for 6to4 and/or Teredo to help improve the
protocol's performance for ambient traffic utilizing these IPv6 protocol's performance for ambient traffic utilizing these IPv6
connectivity methods. Experiences such as those described in connectivity methods. Experiences such as those described in
[I-D.jjmb-v6ops-comcast-ipv6-experiences] show that local relays have [I-D.jjmb-v6ops-comcast-ipv6-experiences] show that local relays have
proved beneficial to 6to4 protocol performance. proved beneficial to 6to4 protocol performance.
Operators should also be aware of breakage cases for 6to4 if non- Operators should also be aware of breakage cases for 6to4 if non-
RFC1918 addresses are used within CGN/NAT444 zones. Many off the RFC1918 addresses are used within CGN/NAT444 zones. Many off-the-
shelf CPEs and operating systems may turn on 6to4 without a valid shelf CPEs and operating systems may turn on 6to4 without a valid
return path to the originating (local) host. This particular usecase return path to the originating (local) host. This particular use
is likely to occur if any space other than [RFC1918] is used, case can occur if any space other than [RFC1918] is used, including
including Shared Address Space [RFC6598] or space registered to Shared Address Space [RFC6598] or space registered to another
another organization (squat space). The operator can use 6to4-PMT organization (squat space). The operator can use 6to4-PMT
[I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel] or attempt to [I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel] or attempt to
block 6to4 operation entirely by blocking the ancycast ranges block 6to4 operation entirely by blocking the anycast ranges
associated with [RFC3068]. associated with [RFC3068].
4.2. Carrier Grade NAT (NAT444) 4.2. Carrier Grade NAT (NAT444)
Carrier Grade NAT (GGN), specifically as deployed in a NAT444 Carrier Grade NAT (CGN), specifically as deployed in a NAT444
scenario [I-D.ietf-behave-lsn-requirements], may prove beneficial for scenario [I-D.ietf-behave-lsn-requirements], may prove beneficial for
those operators who offer Dual Stack services to customer endpoints those operators who offer Dual Stack services to subscriber endpoints
once they exhaust their pools of IPv4 addresses. CGNs, and address once they exhaust their pools of IPv4 addresses. CGNs, and address
sharing overall, are known to cause certain challenges for the IPv4 sharing overall, are known to cause certain challenges for the IPv4
service [RFC6269], but may be necessary depending on how an operator service [RFC6269][I-D.donley-nat444-impacts], but may be necessary
has chosen to deal with IPv6 transition and legacy IPv4 connectivity depending on how an operator has chosen to deal with IPv6 transition
requirements. and legacy IPv4 connectivity requirements.
In a network where IPv4 address availability is low, CGN/NAT444, may In a network where IPv4 address availability is low, CGN/NAT444, may
provide continued access to IPv4 endpoints. Some of the advantages provide continued access to IPv4 endpoints. Some of the advantages
of using CGN/NAT444 include the similarities in provisioning and of using CGN/NAT444 include the similarities in provisioning and
activation models. IPv4 hosts in a CGN/NAT444 deployment will likely activation models. IPv4 hosts in a CGN/NAT444 deployment will likely
inherent the same addressing and management procedures as legacy inherent the same addressing and management procedures as legacy
IPv4, globally addressed hosts (i.e. DHCPv6, DNSv4, TFTP, TR-069 IPv4, globally addressed hosts (i.e. DHCPv6, DNSv4, TFTP, TR-069
etc). etc).
4.3. 6RD 4.3. 6RD
6RD [RFC5969] provides a way of offering IPv6 connectivity to 6RD [RFC5969] provides a way of offering IPv6 connectivity to
customer endpoints when native IPv6 addressing on the access network subscriber endpoints when native IPv6 addressing on the access
is not yet possible. 6RD provides tunnelled connectivity for IPv6 network is not yet possible. 6RD provides tunneled connectivity for
over the existing IPv4 path. As the access edge is upgraded and IPv6 over the existing IPv4 path. As the access edge is upgraded and
customer premise equipment is replaced, 6RD can be replace by native subscriber premise equipment is replaced, 6RD can be replace by
IPv6 connectivity. 6RD can be delivered over top a CGN/NAT444 native IPv6 connectivity. 6RD can be delivered over top a CGN/NAT444
deployment, but this would cause all traffic to be subject to some deployment, but this would cause all traffic to be subject to some
type of transition technology. type of transition technology.
6RD may also be advantageous during the early transition while IPv6 6RD may also be advantageous during the early transition while IPv6
traffic volumes are low. During this period, the operator can gain traffic volumes are low. During this period, the operator can gain
experience with IPv6 on the core and improve their peering framework experience with IPv6 on the core and improve their peering framework
to match those of the IPv4 service. 6RD scales by adding relays to to match those of the IPv4 service. 6RD scales by adding relays to
the operator's network. Another advantage for 6RD is that the the operator's network. Another advantage for 6RD is that the
operator does not need a DHCPv6 address assignment infrastructure and operator does not need a DHCPv6 address assignment infrastructure and
and does not need to support IPv6 routing to the CPE to support a 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 delegated prefix (as it's derived from the IPv4 address and other
configuration parameters). configuration parameters).
Client support is required for 6RD operation and may not be available Client support is required for 6RD operation and may not be available
on deployed hardware. 6RD deployments may require the customer or on deployed hardware. 6RD deployments may require the subscriber or
operator to replace the CPE. 6RD will also require parameter operator to replace the CPE. 6RD will also require parameter
configuration which can be powered by the operator through DHCPv4, configuration which can be powered by the operator through DHCPv4,
manually provisioned on the CPE or automatically through some other manually provisioned on the CPE or automatically through some other
means. Manual provisioning would likely limit deployment scale. means. Manual provisioning would likely limit deployment scale.
4.4. Native Dual Stack 4.4. Native Dual Stack
Native Dual Stack is often referred to as the "Gold Standard" of IPv6 Native Dual Stack is often referred to as the "gold standard" of IPv6
and IPv4 delivery. It is a method of service delivery which is and IPv4 delivery. It is a method of service delivery that is
already used in many existing IPv6 deployments. Native Dual Stack already used in many existing IPv6 deployments. Native Dual Stack
does however require that Native IPv6 be delivered to the customer does, however, require that Native IPv6 be delivered through the
premise. This technology option is desirable in many cases and can access network to the subscriber premise. This technology option is
be used immediately if the access network and customer premise desirable in many cases and can be used immediately if the access
equipment supports native IPv6. network and subscriber premise equipment supports native IPv6.
An operator who runs out of IPv4 addresses to assign to customers An operator who runs out of IPv4 addresses to assign to subscribers
will not be able to provide traditional native Dual Stack will not be able to provide traditional native Dual Stack
connectivity for new customers. In Dual Stack deployments where connectivity for new subscribers. In Dual Stack deployments where
sufficient IPv4 addresses are not available, CGN/NAT444 can be used sufficient IPv4 addresses are not available, CGN/NAT444 can be used
on the IPv4 path. on the IPv4 path.
Delivering native Dual Stack would require the operator's core and Delivering native Dual Stack would require the operator's core and
access network to support IPv6. Other systems like DHCP, DNS, and access network to support IPv6. Other systems like DHCP, DNS, and
diagnostic/management facilities need to be upgraded to support IPv6 diagnostic/management facilities need to be upgraded to support IPv6
as well. The upgrade of such systems may often be non-trivial and as well. The upgrade of such systems may often be non-trivial and
costly. costly.
4.5. DS-Lite 4.5. DS-Lite
Dual-Stack Lite (DS-Lite, [RFC6333]) is based on a native IPv6 Dual-Stack Lite (DS-Lite, [RFC6333]) is based on a native IPv6
connection model where IPv4 services are supported. DS-Lite provides connection model where IPv4 services are supported. DS-Lite provides
tunnelled connectivity for IPv4 over the IPv6 path between the tunneled connectivity for IPv4 over the IPv6 path between the
customer's network device and a provider managed gateway (AFTR). subscriber's network device and a provider managed gateway (AFTR).
DS-Lite can only be used where there is native IPv6 connection DS-Lite can only be used where there is native IPv6 connection
between the AFTR and the CPE. This may mean that the technology's 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 use may not be viable during early transition if the core or access
network lacks IPv6 support. During the early transition period a network lacks IPv6 support. During the early transition period, a
significant amount of content and services may by IPv4-only. significant amount of content and services may by IPv4-only.
Operators may be sensitive to this and may not want the newer IPv6 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 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 their impact. The operator may also want to make sure that most of its
internal services and a significant about of external content is internal services and a significant about of external content is
available over IPv6 before deploying DS-Lite. The availability of available over IPv6 before deploying DS-Lite. The availability of
services on IPv6 would help lower the demand on the AFTRs. services on IPv6 would help lower the demand on the AFTRs.
By sharing IPv4 addresses among multiple endpoints, like CGN/NAT444, By sharing IPv4 addresses among multiple endpoints, like CGN/NAT444,
DS-Lite can facilitate continued support of legacy IPv4 services even DS-Lite can facilitate continued support of legacy IPv4 services even
after IPv4 address run out. There are some functional considerations after IPv4 address run out. There are some functional considerations
to take into account even with DS-Lite such as those described in to take into account with DS-Lite, such as those described in
[I-D.donley-nat444-impacts] and in [I-D.ietf-softwire-dslite-
[I-D.donley-nat444-impacts] and [I-D.ietf-softwire-dslite-
deployment]. deployment].
DS-Lite requires client support on the CPE to function. The ability DS-Lite requires client support on the CPE to function. The ability
to utilize DS-Lite will be dependent on the operator providing DS- to utilize DS-Lite will be dependent on the operator providing DS-
Lite capable CPEs or retail availability of the supported client for Lite capable CPEs or retail availability of the supported client for
customer acquired endpoints. subscriber-acquired endpoints.
4.6. NAT64 4.6. NAT64
NAT64 [RFC6146] provides the ability to connect IPv6-only connected NAT64 [RFC6146] provides the ability to connect IPv6-only connected
clients and hosts to IPv4 servers without any tunnelling. NAT64 clients and hosts to IPv4 servers without any tunneling. NAT64
requires that the host and home network supports IPv6-only modes of requires that the host and home network supports IPv6-only modes of
operation. Home networks do not commonly contain equipment which is operation. Home networks do not commonly contain equipment that is
all IPv6-capable. It is also not anticipated that common home 100% IPv6-capable. It is also not anticipated that common home
networks will be ready for IPv6-only operation for a number of years. networks will be ready for IPv6-only operation for a number of years.
However, IPv6-only networking can be deployed by early adopters or However, IPv6-only networking can be deployed by early adopters or
highly controlled networks. highly controlled networks [RFC6586].
Viability of NAT64 will increase in Wireline networks as consumer Viability of NAT64 will increase in wireline networks as consumer
equipment is replaced by IPv6 capable versions. There are incentives equipment is replaced by IPv6 capable versions. There are incentives
for operators to move to IPv6-only operation, when feasible, which for operators to move to IPv6-only operation, when feasible, which
includes the simplicity of a single stack access network. includes the simplicity of a single stack access network.
5. IPv6 Transition Phases 5. IPv6 Transition Phases
The Phases described in this document are not provided as a rigid set The Phases described in this document are not provided as a rigid set
of steps, but are considered a guideline which should be analyzed by of steps, but are considered a guideline which should be analyzed by
operators planning their IPv6 transition. Operators may choose to operators planning their IPv6 transition. Operators may choose to
skip steps based on technological capabilities within their specific skip steps based on technological capabilities within their specific
networks, (residential/corporate, fixed/mobile), their business networks, (residential/corporate, fixed/mobile), their business
development perspectives (which may affect the pace of migration development perspectives (which may affect the pace of migration
towards full IPv6), or a combination thereof. towards full IPv6), or a combination thereof.
The phases are based on the expectation that IPv6 traffic volume may The phases are based on the expectation that IPv6 traffic volume may
initially be low, and operator staff will gain experience with IPv6 initially be low, and operator staff will gain experience with IPv6
over time. As traffic volumes of IPv6 increase, IPv4 traffic volumes over time. As traffic volumes of IPv6 increase, IPv4 traffic volumes
will correspondingly decrease, until IPv6 is the predominant address will decline (in percentage relative to IPv4), until IPv6 is the
family used. Operators may want to keep the traffic flow for the dominant address family used. Operators may want to keep the traffic
dominant traffic class (IPv4 vs. IPv6) native to help manage costs flow for the dominant traffic class (IPv4 vs. IPv6) native to help
related to transition technologies. The cost of using multiple manage costs related to transition technologies. The cost of using
technologies in succession to optimize each stage of the transition multiple technologies in succession to optimize each stage of the
should also be compared against the cost of changing and upgrading transition should also be compared against the cost of changing and
customer connections. upgrading subscriber connections.
Additional guidance and information on utilizing IPv6 transition Additional guidance and information on utilizing IPv6 transition
mechanisms can be found in [RFC6180]. Also, guidance on incremental mechanisms can be found in [RFC6180]. Also, guidance on incremental
CGN for IPv6 transition can also be found in [RFC6264]. CGN for IPv6 transition can also be found in [RFC6264].
5.1. Phase 0 - Foundation 5.1. Phase 0 - Foundation
5.1.1. Phase 0 - Foundation: Training 5.1.1. Phase 0 - Foundation: Training
Training is one of the most important steps in preparing an Training is one of the most important steps in preparing an
organization to support IPv6. Most people have little experience organization to support IPv6. Most people have little experience
with IPv6, and many do not even have a solid grounding in IPv4. The with IPv6, and many do not even have a solid grounding in IPv4. The
implementation of IPv6 will likely produce many challenges due to implementation of IPv6 will likely produce many challenges due to
immature code on hardware, and the evolution of many applications and immature code on hardware, and the evolution of many applications and
systems to support IPv6. To properly deal with these impending or systems to support IPv6. To properly deal with these impending or
current challenges organizations must train their staff on IPv6. current challenges, organizations must train their staff on IPv6.
Training should also be provided within reasonable timelines from the Training should also be provided within reasonable timelines from the
actual IPv6 deployment. This means the operator needs to plan in actual IPv6 deployment. This means the operator needs to plan in
advance as they train the various parts of their organization. New advance as it trains the various parts of its organization. New
Technology and Engineering staff often receive little training Technology and Engineering staff often receive little training
because of their depth of knowledge, but must at least be provided because of their depth of knowledge, but must at least be provided
opportunities to read documentation, architectural white papers, and opportunities to read documentation, architectural white papers, and
RFCs. Operations staff who support the network and other systems RFCs. Operations personnel who support the network and other systems
need to be trained closer to the deployment timeframes, so they need to be trained closer to the deployment timeframes, so they
immediately use their new-found knowledge before forgetting. immediately use their new-found knowledge before forgetting.
Customer support staff would require much more basic but large scale Subscriber support staff would require much more basic but large
training since many organizations have massive call centres to scale training since many organizations have massive call centers to
support the customer base. Tailored training will also be required support the subscriber base. Tailored training will also be required
for marketing and sales staff to help them understand IPv6 and build for marketing and sales staff to help them understand IPv6 and build
it into the product development and sales process. it into the product development and sales process.
5.1.2. Phase 0 - Foundation: Routing 5.1.2. Phase 0 - Foundation: Routing
The network infrastructure will need to be in place to support IPv6. The network infrastructure will need to be in place to support IPv6.
This includes the routed infrastructure along with addressing This includes the routed infrastructure along with addressing
principles, routing principles, peering policy and related network principles, routing principles, peering policy and related network
functions. Since IPv6 is quite different from IPv4 in several ways functions. Since IPv6 is quite different from IPv4 in several ways
including the number of addresses which are made available, careful including the number of addresses which are made available, careful
attention to a scalable and manageable architecture needs to be made. attention to a scalable and manageable architecture needs to be made.
One such change is the notion of a delegated prefix which deviates One such change is the notion of a delegated prefix, which deviates
from the common single address phenomenon in IPv4-only deployments. from the common single address phenomenon in IPv4-only deployments.
Deploying prefixes per CPE can load the routing tables and require a Deploying prefixes per CPE can load the routing tables and require a
routing protocol or route gleaning to manage connectivity to the routing protocol or route gleaning to manage connectivity to the
customer's network. Delegating prefixes can be of specific subscriber's network. Delegating prefixes can be of specific
importance in access network environments where downstream customers importance in access network environments where downstream subscriber
often move between access nodes, raising the concern of frequent often move between access nodes, raising the concern of frequent
renumbering and/or managing movement of routed prefixes within the renumbering and/or managing movement of routed prefixes within the
network (common in cable based networks). network (common in cable based networks).
5.1.3. Phase 0 - Foundation: Network Policy and Security 5.1.3. Phase 0 - Foundation: Network Policy and Security
Many, but not all, security policies will map easily from IPv4 to Many, but not all, security policies will map easily from IPv4 to
IPv6. Some new policies may be required for issues specific to IPv6 IPv6. Some new policies may be required for issues specific to IPv6
operation. This document does not highlight these specific issues, operation. This document does not highlight these specific issues,
but raises the awareness they are of consideration and should be but raises the awareness they are of consideration and should be
skipping to change at page 14, line 35 skipping to change at page 14, line 41
deployed along side the transition hardware without the need to deployed along side the transition hardware without the need to
distribute these to an excessive or divergent number of locations. distribute these to an excessive or divergent number of locations.
This approach may also prove beneficial if traffic patterns change This approach may also prove beneficial if traffic patterns change
rapidly in the future as the operators may need to evolve their rapidly in the future as the operators may need to evolve their
transition infrastructure faster than originally anticipated. Once transition infrastructure faster than originally anticipated. Once
such example may be the movement from a CGN/NAT44 model (dual stack) such example may be the movement from a CGN/NAT44 model (dual stack)
to DS-Lite. Since both traffic sets require a translation function to DS-Lite. Since both traffic sets require a translation function
(NAT44), synchronized pool management, routing and management system (NAT44), synchronized pool management, routing and management system
positioning can allow rapid movement (notwithstanding the positioning can allow rapid movement (notwithstanding the
technological means to re-provision the customers). technological means to re-provision the subscriber).
Operators should inform their vendors of what technologies they plan Operators should inform their vendors of what technologies they plan
to support over the course of the transition to make sure the to support over the course of the transition to make sure the
equipment is suited to support those modes of operation. This is equipment is suited to support those modes of operation. This is
important for both network gear and customer premise equipment. important for both network gear and subscriber premise equipment.
The operator should also plan their overall strategy to meet the The operator should also plan their overall strategy to meet the
target needs of an IPv6-only deployment. As traffic moves to IPv6, target needs of an IPv6-only deployment. As traffic moves to IPv6,
the benefits of only a single stack on the access network may justify the benefits of only a single stack on the access network may
the removal of IPv4 for simplicity. Planning for this eventual eventually justify the removal of IPv4 for simplicity. Planning for
model, no matter how far off this may be, will help the operator this eventual model, no matter how far off this may be, will help the
embrace this end state when needed. operator embrace this end state when needed.
5.1.5. Phase 0- Foundation: Tools and Management 5.1.5. Phase 0- Foundation: Tools and Management
The operator should thoroughly analyze all provisioning and The operator should thoroughly analyze all provisioning and
management systems to develop requirements for each phase. This will management systems to develop requirements for each phase. This will
include concepts related to the 128-bit IPv6 address, the notation of include concepts related to the 128-bit IPv6 address, the notation of
an assigned IPv6 prefix (PD) and the ability to detect either or both an assigned IPv6 prefix (Prefix Delegation) and the ability to detect
address families when determining if a customer has full Internet either or both address families when determining if a subscriber has
service. full Internet service.
If an operator stores usage information, this would need to be If an operator stores usage information, this would need to be
aggregated to include both the IPv4 and IPv6 traffic flows. Also, aggregated to include both the IPv4 and IPv6 as both address families
tools that verify connectivity may need to query the IPv4 and IPv6 are assigned to the same subscriber. Tools that verify connectivity
addresses. may need to query the IPv4 and IPv6 addresses.
5.2. Phase 1 - Tunnelled IPv6 5.2. Phase 1 - Tunneled IPv6
Tunnelled access to IPv6 can be regarded as an early stage transition Tunneled access to IPv6 can be regarded as an early stage transition
option by operators. Many network operators can deploy native IPv6 option by operators. Many network operators can deploy native IPv6
from the access edge to the peering edge fairly quickly but may not from the access edge to the peering edge fairly quickly but may not
be able to offer IPv6 natively to the customer edge device. During be able to offer IPv6 natively to the subscriber edge device. During
this period of time, tunnelled access to IPv6 is a viable alternative this period of time, tunneled access to IPv6 is a viable alternative
to native IPv6. It is also possible that operators my be rolling out to native IPv6. It is also possible that operators may be rolling
IPv6 natively to the customer edge but the time involved may be long out IPv6 natively to the subscriber edge but the time involved may be
due to logistics and other factors. Even while slowly rolling out long due to logistics and other factors. Even while carefully
native IPv6, operators can deploy relays for automatic tunnelling rolling out native IPv6, operators can deploy relays for automatic
technologies like 6to4 and Teredo. Where native IPv6 to the access tunneling technologies like 6to4 and Teredo. Where native IPv6 to
edge is a longer-term project, operators can consider 6RD [RFC5969] the access edge is a longer-term project, operators can consider 6RD
as an option to offer in-home IPv6 access. Note that 6to4 and Teredo [RFC5969] as an option to offer in-home IPv6 access. Note that 6to4
have different address selection behaviours than 6RD [RFC3484]. and Teredo have different address selection behaviors than 6RD
Additional guidelines on deploying and supporting 6to4 can be found [RFC3484]. Additional guidelines on deploying and supporting 6to4
in [RFC6343]. can be found in [RFC6343].
The operator can deploy 6RD relays into the network and scale them as The operator can deploy 6RD relays into the network and scale them as
needed to meet the early customer needs of IPv6. Since 6RD requires needed to meet the early subscriber needs of IPv6. Since 6RD
the upgrade or replacement of CPE devices, the operator may want requires the upgrade or replacement of CPE devices, the operator may
ensure that the CPE devices support not just 6RD but native Dual want to ensure that the CPE devices support not just 6RD but native
Stack and other tunnelling technologies if possible such as DS-Lite. Dual Stack and other tunneling technologies if possible such as DS-
6RD clients are becoming available in some retail channel products Lite [I-D.ietf-v6ops-6204bis]. 6RD clients are becoming available in
and within the OEM market. Retail availability of 6RD is important some retail channel products and within the OEM market. Retail
since not all operators control or have influence over what equipment availability of 6RD is important since not all operators control or
is deployed in the consumer home network. The operator can support have influence over what equipment is deployed in the consumer home
6RD access with unmanaged devices using DHCPv4 option 212 network. The operator can support 6RD access with unmanaged devices
(OPTION_6RD). using DHCPv4 option 212 (OPTION_6RD) [RFC5969].
+--------+ ----- +--------+ -----
| | / \ | | / \
Encap IPv6 Flow | 6RD | | IPv6 | Encap IPv6 Flow | 6RD | | IPv6 |
- - -> | BR | <- > | Net | - - -> | BR | <- > | Net |
+---------+ / | | \ / +---------+ / | | \ /
| | / +--------+ ----- | | / +--------+ -----
| 6RD + <----- ----- | 6RD + <----- -----
| | / \ | | / \
| Client | IPv4 Flow | IPv4 | | Client | IPv4 Flow | IPv4 |
| + < - - - - - - - - - - - - - - -> | Net | | + < - - - - - - - - - - - - - - -> | Net |
| | \ / | | \ /
+---------+ ----- +---------+ -----
Figure 1: 6RD Basic Model Figure 1: 6RD Basic Model
6RD used as an initial transition technology also provides the added 6RD used as an initial transition technology also provides the added
benefit of a deterministic IPv6 prefix which is based on the IPv4 benefit of a deterministic IPv6 prefix based on the IPv4 assigned
assigned address. Many operational tools are available or have been address. Many operational tools are available or have been built to
built to identify what IPv4 (often dynamic) address was assigned to a identify what IPv4 (often dynamic) address was assigned to a
customer CPE. So a simple tool and/or method can be built to help subscriber CPE. So, a simple tool and/or method can be built to help
the operational staff in an organization know that the IPv6 prefix is identify the IPv6 prefix using the knowledge of the assigned IPv4
for a 6RD serviced CPE based on knowledge of the IPv4 address. address.
An operator may choose to not offer internal services over IPv6 if An operator may choose to not offer internal services over IPv6 if
tunnelled access to IPv6 is used since some services generate a large tunneled access to IPv6 is used since some services generate a large
amount of traffic. Such traffic may include Video content like IPTV. amount of traffic. Such traffic may include Video content like IPTV.
By limiting how much traffic is delivered over the 6RD connection (if By limiting how much traffic is delivered over the 6RD connection (if
possible), the operator can avoid costly and complex scaling of the possible), the operator can avoid costly and complex scaling of the
relay infrastructure. relay infrastructure.
5.2.1. 6RD Deployment Considerations 5.2.1. 6RD Deployment Considerations
Deploying 6RD can greatly speed up an operator's ability to support Deploying 6RD can greatly speed up an operator's ability to support
IPv6 to the customer network if native IPv6 connectivity cannot be IPv6 to the subscriber network if native IPv6 connectivity cannot be
supplied. The speed at which 6RD can be deployed is highlighted in supplied. The speed at which 6RD can be deployed is highlighted in
[RFC5569]. [RFC5569].
The first core consideration is deployment models. 6RD requires the The first core consideration is deployment models. 6RD requires the
CPE (6RD client) to send traffic to a 6RD relay. These relays can CPE (6RD client) to send traffic to a 6RD relay. These relays can
share a common anycast address, or can use unique addresses. Using share a common anycast address, or can use unique addresses. Using
an anycast model, the operator can deploy all the 6RD relays 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 the same IPv4 interior service address. As the load increases on the
deployed relays, the operator can deploy more relays into the deployed relays, the operator can deploy more relays into the
network. The one drawback here is that it may be difficult to manage network. The one drawback is that it may be difficult to manage the
the traffic volume among additional relays, since all 6RD traffic traffic volume among additional relays, since all 6RD traffic will
will find the nearest (in terms of IGP cost) relay. Use of multiple find the nearest (in terms of IGP cost) relay. Use of multiple relay
relay addresses can help provide more control but has the addresses can help provide more control but has the disadvantage of
disadvantage of being more complex to provision as subsets of CPEs being more complex to provision. Subsets of CPEs across the network
across the network will require and contain different relay will require and contain different relay information. An alternative
information. An alternative approach is to use a hybrid model using approach is to use a hybrid model using multiple anycast service IP
multiple anycast service IPs for clusters of 6RD relays should the Addresses for clusters of 6RD relays, should the operator anticipate
operator anticipate massive scaling of the environment. Thus, the massive scaling of the environment. Thus, the operator has multiple
operator has multiple vectors by which to scale the service. vectors by which to scale the service.
+--------+ +--------+
| | | |
IPv4 Addr.X | 6RD | IPv4 Addr.X | 6RD |
- - - > | BR | - - - > | BR |
+-----------+ / | | +-----------+ / | |
| Client A | <- - - +--------+ | Client A | <- - - +--------+
+-----------+ +-----------+
Separate IPv4 Service Addresses Separate IPv4 Service Addresses
+-----------+ +-----------+
skipping to change at page 18, line 5 skipping to change at page 18, line 5
+-----------+ +-----------+
| Client B | - - - +--------+ | Client B | - - - +--------+
+-----------+ \ | | +-----------+ \ | |
- - - > | 6RD | - - - > | 6RD |
IPv4 Addr.X | BR | IPv4 Addr.X | BR |
| | | |
+--------+ +--------+
Figure 3: 6RD Anycast IPv4 Service Address Model Figure 3: 6RD Anycast IPv4 Service Address Model
Provisioning of the endpoints is affected by the deployment model Provisioning of the 6RD endpoints is affected by the deployment model
chosen (i.e. anycast vs. specific service IPs). Using multiple IPs chosen (i.e. anycast vs. specific service IP Addresses). Using
may require more planning and management as customer equipment will multiple IP Addresses may require more planning and management, as
have different sets of data to be provisioned into the devices. The subscriber equipment will have different sets of data to be
operator may use DHCPv4, manual provisioning or other mechanisms to provisioned into the devices. The operator may use DHCPv4, manual
provide parameters to customer equipment. provisioning or other mechanisms to provide parameters to subscriber
equipment.
If the operator manages the CPE, support personnel will need tools If the operator manages the CPE, support personnel will need tools
able to report the status of the 6RD tunnel. Usage information can able to report the status of the 6RD tunnel. Usage information can
be counted on the operator edge, but if it requires source/ be counted on the operator edge, but if it requires source/
destination flow details, data must be collected after the 6RD relay destination flow details, data must be collected after the 6RD relay
(IPv6 side of connection). (IPv6 side of connection).
6RD [RFC5969], as any tunneling option, is subject to a reduced MTU
so operators need to plan to manage this environment.
+---------+ IPv4 Encapsulation +------------+ +---------+ IPv4 Encapsulation +------------+
| +- - - - - - - - - - - + | | +- - - - - - - - - - - + |
| 6RD +----------------------+ 6RD +--------- | 6RD +----------------------+ 6RD +---------
| | IPv6 Packet | Relay | IPv6 Packet | | IPv6 Packet | Relay | IPv6 Packet
| Client +----------------------+ +--------- | Client +----------------------+ +---------
| +- - - - - - - - - - - + | ^ | +- - - - - - - - - - - + | ^
+---------+ ^ +------------+ | +---------+ ^ +------------+ |
| | | |
| | | |
IPv4 IP (Tools/Mgmt) IPv6 Flow Analysis IPv4 IP (Tools/Mgmt) IPv6 Flow Analysis
Figure 4: 6RD Tools and Flow Management Figure 4: 6RD Tools and Flow Management
5.3. Phase 2: Native Dual Stack 5.3. Phase 2: Native Dual Stack
Either as a follow-up phase to "Tunnelled IPv6" or as an initial Either as a follow-up phase to "Tunneled IPv6" or as an initial step,
step, the operator may deploy native IPv6 down to the CPEs. This the operator may deploy native IPv6 down to the CPEs. This phase
phase would then allow for both IPv6 and IPv4 to be natively accessed would then allow for both IPv6 and IPv4 to be natively accessed by
by the customer home network without translation or tunnelling. The the subscriber home network without translation or tunneling. The
native Dual Stack phase can be rolled out across the network while native Dual Stack phase can be rolled out across the network while
the tunnelled IPv6 service remains operational, if used. As areas the tunneled IPv6 service remains operational, if used. As areas
begin to support native IPv6, customer home equipment will generally begin to support native IPv6, subscriber home equipment will
prefer using the IPv6 addresses derived from the delegated IPv6 generally prefer using the IPv6 addresses derived from the delegated
prefix versus tunnelling options such as 6to4, 6RD and Teredo as IPv6 prefix versus tunneling options such as 6to4 and Teredo as
defined in [RFC3484] defined in [RFC3484]. Specific care is needed when moving to native
Dual Stack from 6RD as documented in
[I-D.townsley-v6ops-6rd-sunsetting].
Native Dual Stack is the best option at this point in the transition, 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 and should be sought as soon as possible. During this phase, the
operator can confidently move both internal and external services to operator can confidently move both internal and external services to
IPv6. Since there are no translation devices needed for this mode of IPv6. Since there are no translation devices needed for this mode of
operation, it transports both protocols (IPv6 and IPv4) efficiently operation, it transports both protocols (IPv6 and IPv4) efficiently
within the network. within the network.
5.3.1. Native Dual Stack Deployment Considerations 5.3.1. Native Dual Stack Deployment Considerations
Native Dual Stack is a very desirable option for the IPv6 transition Native Dual Stack is a very desirable option for the IPv6 transition,
if feasible. The operator must enable IPv6 on the network core and if feasible. The operator must enable IPv6 on the network core and
peering edge before they attempt to turn on native IPv6 services. peering edge before they attempt to turn on native IPv6 services.
Additionally, provisioning and support systems such as DHCPv6, DNS Additionally, provisioning and support systems such as DHCPv6, DNS
and other functions which support the customer's IPv6 Internet and other functions that support the subscriber's IPv6 Internet
connection need to be in place. connection need to be in place.
The operator must treat IPv6 connectivity with the same operational The operator must treat IPv6 connectivity with the same operational
importance as IPv4. Poor IPv6 service may be worse than not offering importance as IPv4. A poor IPv6 service may be worse than not
an IPv6 service at all, since users may cause users to disable IPv6 offering an IPv6 service at all as it will negatively impact the
and negatively impact their Internet experience. New code and IPv6 subscriber's Internet experience. This may cause users or support
functionality may cause instability at first. The operator will need personnel to disable IPv6, limiting the subscriber from the benefits
to monitor, troubleshoot and resolve issues promptly. of IPv6 connectivity as the 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 Prefix assignment and routing are new for common residential
services. Prefix assignment is straightforward (DHCPv6 using services. Prefix assignment is straightforward (DHCPv6 using
IA_PDs), but installation and propagation of routing information for IA_PDs), but installation and propagation of routing information for
the prefix, especially during access layer instability, is often the prefix, especially during access layer instability, is often
poorly understood. The Operator should develop processes for poorly understood. The operator should develop processes for
renumbering customers who move to new Access nodes. renumbering subscribers who move to new access nodes.
Operators need to keep track of both the dynamically assigned IPv4 Operators need to keep track of both the dynamically assigned IPv4
address along with the IPv6 address and prefix. Any additional address along with the IPv6 address and prefix. Any additional
dynamic elements, such as auto-generated host names, need to be dynamic elements, such as auto-generated host names, need to be
considered and planned for. considered and planned for.
5.4. Intermediate Phase for CGN 5.4. Intermediate Phase for CGN
Acquiring more IPv4 addresses is already challenging, if not Acquiring more IPv4 addresses is already challenging, if not
impossible, therefore address sharing may be required on the IPv4 impossible; therefore address sharing may be required on the IPv4
path. The operator may have a preference to move directly to a more path. The operator may have a preference to move directly to a
efficient way of IPv4 address sharing such as DS-Lite, but conditions transition technology such as DS-Lite [RFC6333] or may choose CGN/
may dictate that CGN/NAT444 is the only workable option. CGN/NAT444 NAT444 to facilitate IPv4 connections. CGN/NAT444 requires IPv4
is less optimal and should be used cautiously in a 6RD deployment (if addressing between the subscriber premise equipment and the
used with 6RD to a given endpoint) since all traffic must traverse operator's translator which may be facilitated by shared address
some type of operator service node (relay and translator). [RFC6598], private address [RFC1918] or other address space. CGN/
NAT444 should be used cautiously if used simultaneously with 6RD for
a common set of subscribers. Operators should be aware that if CGN/
NAT444 is used in such manner, subscriber all traffic must traverse
some type of operator service node (relay and translator). Also,
care should be taken so as not to run 6RD through a DS-Lite tunnel or
vice versa.
+--------+ ----- +--------+ -----
| | / \ | | / \
IPv4 Flow | CGN | | | IPv4 Flow | CGN | | |
- - -> + + < -> | | - - -> + + < -> | |
+---------+ / | | | | +---------+ / | | | |
| CPE | <- - - / +--------+ | IPv4 | | CPE | <- - - / +--------+ | IPv4 |
|---------+ | Net | |---------+ | Net |
| | | |
+---------+ IPv4 Flow | | +---------+ IPv4 Flow | |
| CPE | <- - - - - - - - - - - - - - - > | | | CPE | <- - - - - - - - - - - - - - - > | |
|---------+ \ / |---------+ \ /
----- -----
Figure 5: Overlay CGN Deployment Figure 5: Overlay CGN Deployment
In the case of native Dual Stack, CGN/NAT444 can be used to assist in 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 extending connectivity for the IPv4 path while the IPv6 path remains
native. For endpoints operating in a IPv6+CGN/NAT444 model the native. For endpoints operating in a IPv6+CGN/NAT444 model, the
native IPv6 path is available for higher quality connectivity helping native IPv6 path is available for higher quality connectivity,
host operation over the network while the CGN path may offer a less helping host operation over the network. At the same time, the CGN
than optimal performance. These points are also true for DS-Lite. path may offer a less than optimal performance. These points are
also true for DS-Lite.
+--------+ ----- +--------+ -----
| | / \ | | / \
IPv4 Flow | CGN | | IPv4 | IPv4 Flow | CGN | | IPv4 |
- - -> + + < -> | Net | - - -> + + < -> | Net |
+---------+ / | | \ / +---------+ / | | \ /
| | <- - - / +--------+ ------- | | <- - - / +--------+ -------
| Dual | | Dual |
| Stack | ----- | Stack | -----
| CPE | IPv6 Flow / IPv6 \ | CPE | IPv6 Flow / IPv6 \
| | <- - - - - - - - - - - - - - - > | Net | | | <- - - - - - - - - - - - - - - > | Net |
|---------+ \ / |---------+ \ /
----- -----
Figure 6: Dual Stack with CGN Figure 6: Dual Stack with CGN
CGN/NAT444 deployments may make use of a number of address options CGN/NAT444 deployments may make use of a number of address options,
which include RFC1918 or Shared Address Space [RFC6598]. It is also which include [RFC1918] or Shared Address Space [RFC6598]. It is
possible that operators may use part of their own RIR assigned also possible that operators may use part of their own RIR assigned
address space for CGN zone addressing if [RFC1918] addresses pose address space for CGN zone addressing if [RFC1918] addresses pose
technical challenges in their network. It is not recommended that technical challenges in their network. It is not recommended that
operators use squat space as it may pose additional challenges with operators use 'squat space', as it may pose additional challenges
filtering and policy control, with filtering and policy control [RFC6598].
5.4.1. CGN Deployment Considerations 5.4.1. CGN Deployment Considerations
CGN is often considered undesirable by operators but required in many CGN is often considered undesirable by operators but required in many
cases. An operator who needs to deploy CGN capabilities should cases. An operator who needs to deploy CGN capabilities should
consider the impacts of the function to the network. CGN is often consider the impacts of the function to the network. CGN is often
deployed in addition to running IPv4 services and should not deployed in addition to running IPv4 services and should not
negatively impact the already working Native IPv4 service. CGNs will negatively impact the already working Native IPv4 service. CGNs will
also be needed at low scale at first and grown to meet the demands be needed at low scale at first and grown to meet the demands based
based on traffic and connection dynamics of the customer, content and on traffic and connection dynamics of the subscriber, content and
network peers. network peers.
The operator may want to deploy CGNs more centrally at first and then The operator may want to deploy CGNs more centrally at first and then
scale the system as needed. This approach can help conserve costs of scale the system as needed. This approach can help conserve costs of
the system and only spend money on equipment based on the actual the system limiting the deploy based and scaling it based on actual
growth of traffic (demand on CGN system). The operator will need a traffic demand. The operator should use a deployment model and
deployment model and architecture which allows the system to scale as architecture which allows the system to scale as needed.
needed.
+--------+ ----- +--------+ -----
| | / \ | | / \
| CGN | | | | CGN | | |
- - -> + + < -> | | - - -> + + < -> | |
+---------+ / | | | | +---------+ / | | | |
| CPE | <- - - / +--------+ | IPv4 | | CPE | <- - - / +--------+ | IPv4 |
| | ^ | | | | ^ | |
|---------+ | | Net | |---------+ | | Net |
+--------+ Centralized | | +--------+ Centralized | |
skipping to change at page 21, line 44 skipping to change at page 21, line 49
| CPE | <- > + + <- - - - - - - > | | | CPE | <- > + + <- - - - - - - > | |
|---------+ | | \ / |---------+ | | \ /
+--------+ ----- +--------+ -----
^ ^
| |
Distributed CGN Distributed CGN
Figure 7: CGN Deployment: Centralized vs. Distributed Figure 7: CGN Deployment: Centralized vs. Distributed
The operator may be required to log translation information The operator may be required to log translation information
[I-D.sivakumar-behave-nat-logging]. This logging may require [I-D.ietf-behave-lsn-requirements]. This logging may require
significant investment in external systems which ingest, aggregate significant investment in external systems which ingest, aggregate
and report on such information [I-D.donley-behave-deterministic-cgn]. and report on such information [I-D.donley-behave-deterministic-cgn].
Since CGN has noticeable impacts on certain applications [I.D.donley- Since CGN has noticeable impacts on certain applications [I-D.donley-
nat444-impacts], operators may deploy CGN only for those customers nat444-impacts], operators may deploy CGN only for those subscribers
who may not likely be affected by CGN (if possible). who may be less affected by CGN (if possible).
5.5. Phase 3 - IPv6-Only 5.5. Phase 3 - IPv6-Only
Once Native IPv6 is widely deployed in the network and well-supported Once Native IPv6 is widely deployed in the network and well-supported
by tools, staff, and processes, an operator may consider supporting by tools, staff, and processes, an operator may consider supporting
only IPv6 to all or some customer endpoints. During this final only IPv6 to all or some subscriber endpoints. During this final
phase, IPv4 connectivity may or may not need to be supported phase, IPv4 connectivity may or may not need to be supported,
depending on the conditions of the network and customer demand. If depending on the conditions of the network and subscriber demand. If
legacy IPv4 connectivity is still demanded, DS-Lite may be used to legacy IPv4 connectivity is still demanded (e.g. for older nodes),
tunnel the traffic. If IPv4 connectivity is not required, but access DS-Lite [RFC6333] may be used to tunnel the traffic. If IPv4
to legacy IPv4 content is , then NAT64 can be used. connectivity is not required, but access to legacy IPv4 content is,
then NAT64 [RFC6144][RFC6146] can be used.
DS-Lite allows continued access for the IPv4 customer base using DS-Lite allows continued access for the IPv4 subscriber base using
address sharing for IPv4 Internet connectivity, but with only a address sharing for IPv4 Internet connectivity, but with only a
single layer of translation, compared to CGN/NAT444. This mode of single layer of translation, compared to CGN/NAT444. This mode of
operation also removes the need to directly address customer operation also removes the need to directly supply subscriber
endpoints with an IPv4 address simplifying the connectivity to the endpoints with an IPv4 address, potentially simplifying the
customer (single address family) and supporting IPv6 only addressing connectivity to the customer (single address family) and supporting
to the CPE. IPv6 only addressing to the CPE.
The operator can also move Dual Stack endpoints to DS-Lite The operator can also move Dual Stack endpoints to DS-Lite
retroactively to help optimize the IPv4 address sharing deployment by retroactively to help optimize the IPv4 address sharing deployment by
removing the IPv4 address assignment and routing component. To removing the IPv4 address assignment and routing component. To
minimize traffic needing translation, the operator should have minimize traffic needing translation, the operator should have
already moved most content to IPv6 before the IPv6-only phase is already moved most content to IPv6 before the IPv6-only phase is
implemented. implemented.
+--------+ ----- +--------+ -----
| | / \ | | / \
Encap IPv4 Flow | AFTR | | IPv4 | Encap IPv4 Flow | AFTR | | IPv4 |
skipping to change at page 22, line 45 skipping to change at page 23, line 5
| | / +--------+ ----- | | / +--------+ -----
| DS-Lite +------- ----- | DS-Lite +------- -----
| | / \ | | / \
| Client | IPv6 Flow | IPv6 | | Client | IPv6 Flow | IPv6 |
| +-------------------------------| Net | | +-------------------------------| Net |
| | \ / | | \ /
+---------+ ----- +---------+ -----
Figure 8: DS-Lite Basic Model Figure 8: DS-Lite Basic Model
If the operator decided to enable a CGN/NAT444 deployment, they may If the operator had previously decided to enable a CGN/NAT444
be able to co-locate the AFTR and CGN/NAT444 processing functions deployment, it may be able to co-locate the AFTR and CGN/NAT444
within a common network location to simplify capacity management and processing functions within a common network location to simplify
the engineering of flows. This case may be evident in a later capacity management and the engineering of flows. This case may be
transition stages when an operator chooses to optimize their network evident in a later transition stages when an operator chooses to
and IPv6-only operation is feasible. optimize its network and IPv6-only operation is feasible.
5.5.1. DS-Lite Deployment Considerations 5.5.1. DS-Lite Deployment Considerations
The same deployment considerations associated with Native IPv6 The same deployment considerations associated with Native IPv6
deployments apply to DS-LIte and NAT64. IPv4 will now be dependent deployments apply to DS-Lite and NAT64. IPv4 will now be dependent
on IPv6 service quality, so the IPv6 network and services must be on IPv6 service quality, so the IPv6 network and services must be
running well to ensure a quality experience for the end customer. running well to ensure a quality experience for the end subscriber.
Tools and processes will be needed to manage the encapsulated IPv4 Tools and processes will be needed to manage the encapsulated IPv4
service. If flow analysis is required for IPv4 traffic, this should service. If flow analysis is required for IPv4 traffic, this may be
be enabled at a point beyond the AFTR (after de-capsulation). enabled at a point beyond the AFTR (after de-capsulation) or DS-Lite
[RFC6333] aware equipment is used to process traffic midstream.
+---------+ IPv4 Encapsulation +------------+ +---------+ IPv6 Encapsulation +------------+
| + - - - - - - - - - - -+ | | + - - - - - - - - - - -+ |
| AFTR +----------------------+ AFTR +--------- | AFTR +----------------------+ AFTR +---------
| | IPv4 Packet | | IPv4 Packet | | IPv4 Packet | | IPv4 Packet
| Client +----------------------+ +--------- | Client +----------------------+ +---------
| + - - - - - - - - - - -+ | ^ | + - - - - - - - - - - -+ | ^
+---------+ ^ +------------+ | +---------+ ^ ^ +------------+ |
| | | | |
| | | | |
IPv6 IP (Tools/Mgmt) IPv4 Packet Flow Analysis IPv6 IP (Tools/Mgmt) | IPv4 Packet Flow Analysis
|
Midstream IPv4 Packet Flow Analysis (Encapsulation Aware)
Figure 9: DS-Lite Tools and Flow Analysis Figure 9: DS-Lite Tools and Flow Analysis
DS-Lite also requires client support. The operator must clearly DS-Lite [RFC6333] also requires client support on the subscribers
articulate to vendors which technologies will be used at which premise device. The operator must clearly articulate to vendors
points, how they interact with each other at the CPE, and how they which technologies will be used at which points, how they interact
will be provisioned. As an example, an operator may use 6RD in the with each other at the CPE, and how they will be provisioned. As an
outset of the transition, then move to Native Dual Stack followed by example, an operator may use 6RD in the outset of the transition,
DS-Lite. then move to Native Dual Stack followed by DS-Lite.
DS-Lite [RFC6333], as any tunneling option, is subject to a reduced
MTU so operators need to plan to manage this environment. Additional
considerations for DS-Lite deployments can be found in [I-D.ietf-
softwire-dslite-deployment].
5.5.2. NAT64 Deployment Considerations 5.5.2. NAT64 Deployment Considerations
The deployment of NAT64 assumes the network assigns an IPv6 addresses The deployment of NAT64 assumes the network assigns an IPv6 address
to an network endpoint which are translated to IPv4 addresses to to a network endpoint that is translated to an IPv4 address to
provide connectivity to IPv4 Internet services and content. provide connectivity to IPv4 Internet services and content.
Experiments such as the one described in [RFC6586] highlight issues Experiments such as the one described in [RFC6586] highlight issues
related to IPv6-only deployments due to legacy IPv4 APIs and IPv4 related to IPv6-only deployments due to legacy IPv4 APIs and IPv4
literals. Many of these issues will be resolved by the eventual literals. Many of these issues will be resolved by the eventual
removal this undesired legacy behaviour. In the short term, removal this undesired legacy behavior. Operational deployment
technology options include the 464xlat [I-D.ietf-v6ops-464xlat] model models, considerations and experiences related to NAT64 have been
which helps managed legacy IPv4 calls. Operational deployment models documented in [I-D.chen-v6ops-nat64-experience].
and experiences related to NAT64 have been documented in [I-D.chen-
v6ops-nat64-experience].
As the support for IPv6 increased within content and network +--------+ -----
endpoints, the more efficient the IPv6-Only model becomes with NAT64. | | / \
IPv6 Flow | NAT64 | | IPv4 |
-------+ DNS64 +---+ Net |
+---------+ / | | \ /
| | / +--------+ -----
| IPv6 +------- -----
| | / \
| Only | IPv6 Flow | IPv6 |
| +-------------------------------| Net |
| | \ /
+---------+ -----
The NAT64 deployment would see an overall declined in usage as more Figure 10: NAT64/DNS64 Basic Model
traffic is promoted to IPv6 to IPv6 native communication. NAT64 may
play an important part of an operators late stage transition as it To navigate around some of the limitations of NAT64 when dealing with
removes the need to support IPv4 on the access network and provides a legacy IPv4 applications, the operator may choose to implement
solid go-forward networking model. 464XLAT [I-D.ietf-v6ops-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. The NAT64
deployment would see an overall decline in usage as more traffic is
promoted to IPv6-to-IPv6 native communication. NAT64 may play an
important part of 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.
6. IANA Considerations 6. IANA Considerations
No IANA considerations are defined at this time. No IANA considerations are defined at this time.
7. Security Considerations 7. Security Considerations
No Additional Security Considerations are made in this document. 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 around tunnelling technologies.
8. Acknowledgements 8. Acknowledgements
Special thanks to Wes George, Christian Jacquenet and John Brzozowski Special thanks to Wes George, Chris Donley, Christian Jacquenet and
for their extensive review and comments. John Brzozowski for their extensive review and comments.
Thanks to the following people for their textual contributions and/or Thanks to the following people for their textual contributions,
guidance on IPv6 deployment considerations: Jason Weil, Gang Chen, guidance and comments: Jason Weil, Gang Chen, Nik Lavorato, John
Nik Lavorato, John Cianfarani, Chris Donley, and Tina TSOU. Cianfarani, Chris Donley, Tina TSOU, Fred Baker and Randy Bush.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC6180] Arkko, J. and F. Baker, "Guidelines for Using IPv6 [RFC6180] Arkko, J. and F. Baker, "Guidelines for Using IPv6
Transition Mechanisms during IPv6 Deployment", RFC 6180, Transition Mechanisms during IPv6 Deployment", RFC 6180,
May 2011. May 2011.
9.2. Informative References 9.2. Informative References
skipping to change at page 25, line 7 skipping to change at page 25, line 41
March 2012. March 2012.
[I-D.donley-behave-deterministic-cgn] [I-D.donley-behave-deterministic-cgn]
Donley, C., Grundemann, C., Sarawat, V., and K. Donley, C., Grundemann, C., Sarawat, V., and K.
Sundaresan, "Deterministic Address Mapping to Reduce Sundaresan, "Deterministic Address Mapping to Reduce
Logging in Carrier Grade NAT Deployments", Logging in Carrier Grade NAT Deployments",
draft-donley-behave-deterministic-cgn-02 (work in draft-donley-behave-deterministic-cgn-02 (work in
progress), March 2012. progress), March 2012.
[I-D.donley-nat444-impacts] [I-D.donley-nat444-impacts]
Donley, C., Howard, L., Colorado, U., and V. Kuarsingh, Donley, C., Howard, L., Kuarsingh, V., Berg, J., and U.
"Assessing the Impact of Carrier-Grade NAT on Network Colorado, "Assessing the Impact of Carrier-Grade NAT on
Applications", draft-donley-nat444-impacts-03 (work in Network Applications", draft-donley-nat444-impacts-04
progress), November 2011. (work in progress), May 2012.
[I-D.ieft-softwire-dslite-deployment]
Lee, Y., Maglione, R., Williams, C., and C. Jacquenet,
"Deployment Considerations for Dual-Stack Lite",
draft-ieft-softwire-dslite-deployment-00 (work in
progress), September 2011.
[I-D.ietf-behave-lsn-requirements] [I-D.ietf-behave-lsn-requirements]
Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A., Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common requirements for Carrier Grade NATs and H. Ashida, "Common requirements for Carrier Grade NATs
(CGNs)", draft-ietf-behave-lsn-requirements-06 (work in (CGNs)", draft-ietf-behave-lsn-requirements-06 (work in
progress), May 2012. progress), May 2012.
[I-D.ietf-softwire-dslite-deployment]
Lee, Y., Maglione, R., Williams, C., Jacquenet, C., and M.
Boucadair, "Deployment Considerations for Dual-Stack
Lite", draft-ietf-softwire-dslite-deployment-03 (work in
progress), March 2012.
[I-D.ietf-v6ops-464xlat] [I-D.ietf-v6ops-464xlat]
Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT: Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation", Combination of Stateful and Stateless Translation",
draft-ietf-v6ops-464xlat-03 (work in progress), May 2012. draft-ietf-v6ops-464xlat-03 (work in progress), May 2012.
[I-D.ietf-v6ops-6204bis]
Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers",
draft-ietf-v6ops-6204bis-09 (work in progress), May 2012.
[I-D.jjmb-v6ops-comcast-ipv6-experiences] [I-D.jjmb-v6ops-comcast-ipv6-experiences]
Brzozowski, J. and C. Griffiths, "Comcast IPv6 Trial/ Brzozowski, J. and C. Griffiths, "Comcast IPv6 Trial/
Deployment Experiences", Deployment Experiences",
draft-jjmb-v6ops-comcast-ipv6-experiences-02 (work in draft-jjmb-v6ops-comcast-ipv6-experiences-02 (work in
progress), October 2011. progress), October 2011.
[I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel] [I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel]
Kuarsingh, V., Lee, Y., and O. Vautrin, "6to4 Provider Kuarsingh, V., Lee, Y., and O. Vautrin, "6to4 Provider
Managed Tunnels", Managed Tunnels",
draft-kuarsingh-v6ops-6to4-provider-managed-tunnel-05 draft-kuarsingh-v6ops-6to4-provider-managed-tunnel-06
(work in progress), February 2012. (work in progress), May 2012.
[I-D.sivakumar-behave-nat-logging] [I-D.townsley-v6ops-6rd-sunsetting]
Sivakumar, S., "Logging of NAT Events", Cassen, A. and M. Townsley, "6rd Sunsetting",
draft-sivakumar-behave-nat-logging-03 (work in progress), draft-townsley-v6ops-6rd-sunsetting-00 (work in progress),
October 2011. November 2011.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996. 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 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
via IPv4 Clouds", RFC 3056, February 2001. via IPv4 Clouds", RFC 3056, February 2001.
[RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers", [RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
RFC 3068, June 2001. RFC 3068, June 2001.
[RFC3484] Draves, R., "Default Address Selection for Internet [RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003. Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through
skipping to change at page 26, line 31 skipping to change at page 27, line 28
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010. RFC 5969, August 2010.
[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in
Customer Premises Equipment (CPE) for Providing Customer Premises Equipment (CPE) for Providing
Residential IPv6 Internet Service", RFC 6092, Residential IPv6 Internet Service", RFC 6092,
January 2011. 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 [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011. Clients to IPv4 Servers", RFC 6146, April 2011.
[RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security [RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns with IP Tunneling", RFC 6169, April 2011. Concerns with IP Tunneling", RFC 6169, April 2011.
[RFC6264] Jiang, S., Guo, D., and B. Carpenter, "An Incremental [RFC6264] Jiang, S., Guo, D., and B. Carpenter, "An Incremental
Carrier-Grade NAT (CGN) for IPv6 Transition", RFC 6264, Carrier-Grade NAT (CGN) for IPv6 Transition", RFC 6264,
June 2011. June 2011.
skipping to change at page 27, line 5 skipping to change at page 28, line 5
Roberts, "Issues with IP Address Sharing", RFC 6269, Roberts, "Issues with IP Address Sharing", RFC 6269,
June 2011. June 2011.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4 Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011. Exhaustion", RFC 6333, August 2011.
[RFC6343] Carpenter, B., "Advisory Guidelines for 6to4 Deployment", [RFC6343] Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
RFC 6343, August 2011. 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.
[RFC6586] Arkko, J. and A. Keranen, "Experiences from an IPv6-Only [RFC6586] Arkko, J. and A. Keranen, "Experiences from an IPv6-Only
Network", RFC 6586, April 2012. Network", RFC 6586, April 2012.
[RFC6598] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and [RFC6598] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and
M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address
Space", BCP 153, RFC 6598, April 2012. Space", BCP 153, RFC 6598, April 2012.
Authors' Addresses Authors' Addresses
Victor Kuarsingh (editor) Victor Kuarsingh (editor)
 End of changes. 128 change blocks. 
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