draft-ietf-v6ops-transition-ipv4aas-15.txt   rfc8585.txt 
IPv6 Operations (v6ops) J. Palet Martinez Internet Engineering Task Force (IETF) J. Palet Martinez
Internet-Draft The IPv6 Company Request for Comments: 8585 The IPv6 Company
Intended status: Informational H. M.-H. Liu Category: Informational H. M.-H. Liu
Expires: August 1, 2019 D-Link Systems, Inc. ISSN: 2070-1721 D-Link Systems, Inc.
M. Kawashima M. Kawashima
NEC Platforms, Ltd. NEC Platforms, Ltd.
January 28, 2019 May 2019
Requirements for IPv6 Customer Edge Routers to Support IPv4 Connectivity Requirements for IPv6 Customer Edge Routers
as-a-Service to Support IPv4-as-a-Service
draft-ietf-v6ops-transition-ipv4aas-15
Abstract Abstract
This document specifies the IPv4 service continuity requirements for This document specifies the IPv4 service continuity requirements for
an IPv6 Customer Edge (CE) router, either provided by the service IPv6 Customer Edge (CE) routers that are provided either by the
provider or by vendors who sell through the retail market. service provider or by vendors who sell through the retail market.
Specifically, this document extends the "Basic Requirements for IPv6 Specifically, this document extends the basic requirements for IPv6
Customer Edge Routers" (RFC7084) in order to allow the provisioning CE routers as described in RFC 7084 to allow the provisioning of IPv6
of IPv6 transition services for the support of "IPv4 as-a-Service" transition services for the support of IPv4-as-a-Service (IPv4aaS) by
(IPv4aaS) by means of new transition mechanisms. The document only means of new transition mechanisms. The document only covers
covers transition technologies for delivering IPv4 in IPv6-only IPv4aaS, i.e., transition technologies for delivering IPv4 in
access networks, commonly called "IPv4 as-a-Service" (IPv4aaS). This IPv6-only access networks. IPv4aaS is necessary because there aren't
is necessary because there aren't sufficient IPv4 addresses available sufficient IPv4 addresses available for every possible customer/
for every possible customer/device. However, devices or applications device. However, devices or applications in the customer Local Area
in the customer LANs (Local Area Networks) may be IPv4-only or Networks (LANs) may be IPv4-only or IPv6-only and still need to
IPv6-only and still need to communicate with IPv4-only services at communicate with IPv4-only services on the Internet.
the Internet.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This document is not an Internet Standards Track specification; it is
provisions of BCP 78 and BCP 79. published for informational purposes.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
This Internet-Draft will expire on August 1, 2019. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8585.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. LAN-Side Configuration . . . . . . . . . . . . . . . . . 6 3.1. LAN-Side Configuration . . . . . . . . . . . . . . . . . 5
3.2. Transition Technologies Support for IPv4 Service 3.2. Transition Technologies Support for IPv4 Service
Continuity (IPv4 as-a-Service - IPv4aaS) . . . . . 6 Continuity (IPv4-as-a-Service) . . . . . . . . . . . . . 5
3.2.1. 464XLAT . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.1. 464XLAT . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . . 9 3.2.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . . 8
3.2.3. Lightweight 4over6 (lw4o6) . . . . . . . . . . . . . 10 3.2.3. Lightweight 4over6 (lw4o6) . . . . . . . . . . . . . 9
3.2.4. MAP-E . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2.4. MAP-E . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.5. MAP-T . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2.5. MAP-T . . . . . . . . . . . . . . . . . . . . . . . . 10
4. IPv4 Multicast Support . . . . . . . . . . . . . . . . . . . 11 4. IPv4 Multicast Support . . . . . . . . . . . . . . . . . . . 11
5. UPnP Support . . . . . . . . . . . . . . . . . . . . . . . . 12 5. UPnP Support . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Comparison to RFC7084 . . . . . . . . . . . . . . . . . . . . 12 6. Comparison to RFC 7084 . . . . . . . . . . . . . . . . . . . 12
7. Code Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. Code Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11. Annex A: Usage Scenarios . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 13
12. Annex B: End-User Network Architecture . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . 16
13. ANNEX C: Changes from -00 . . . . . . . . . . . . . . . . . . 18 Appendix A. Usage Scenarios . . . . . . . . . . . . . . . . . . 17
14. ANNEX D: Changes from -01 . . . . . . . . . . . . . . . . . . 18 Appendix B. End-User Network Architecture . . . . . . . . . . . 18
15. ANNEX E: Changes from -02 . . . . . . . . . . . . . . . . . . 18 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 21
16. ANNEX F: Changes from -03 . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
17. ANNEX G: Changes from -04 . . . . . . . . . . . . . . . . . . 19
18. ANNEX H: Changes from -05 . . . . . . . . . . . . . . . . . . 19
19. ANNEX I: Changes from -06 . . . . . . . . . . . . . . . . . . 19
20. ANNEX J: Changes from -07 . . . . . . . . . . . . . . . . . . 19
21. ANNEX K: Changes from -08, -09 and -10 . . . . . . . . . . . 20
22. ANNEX L: Changes from -11, -12, -13 and -14 . . . . . . . . . 20
23. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
23.1. Normative References . . . . . . . . . . . . . . . . . . 20
23.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
This document defines IPv4 service continuity features over an This document defines IPv4 service continuity features over an
IPv6-only network, for a residential or small-office router, referred IPv6-only network for residential or small office routers (referred
to as an "IPv6 Transition CE Router", in order to establish an to as "IPv6 Transition CE Routers") in order to establish an industry
industry baseline for transition features to be implemented on such a baseline for transition features to be implemented on such routers.
router.
These routers rely upon "Basic Requirements for IPv6 Customer Edge These routers rely upon requirements for IPv6 CE routers defined in
Routers" [RFC7084]. The scope of this document is to ensure the IPv4 [RFC7084]. The scope of this document is to ensure IPv4 service
"service continuity" support, for devices in the LAN side. This continuity support for devices in the LAN side. This ensures that
ensures that remote IPv4-only services continue to be accessible, remote IPv4-only services continue to be accessible, for both
from an IPv6-only Internet Service Provider (ISP) access network from IPv4-only and IPv6-only applications and devices, located in the LAN
both, IPv4-only and IPv6-only applications and devices in the LAN side behind an IPv6 Transition CE Router connected to an IPv6-only
side. These ISP access networks are typically referred to as Wide access network. These ISP access networks are typically referred to
Area Networks (WANs), even if in some cases they may be metropolitan as Wide Area Networks (WANs), even if they may be metropolitan or
or regional. Figure 1 presents a simplified view of this regional in some cases. Figure 1 presents a simplified view of this
architecture. architecture.
+------------+ +------------+ \ +------------+ +------------+ \
| IPv4-only | | IPv4/IPv6 | \ | IPv4-only | | IPv4/IPv6 | \
| Remote | | Remote | | | Remote | | Remote | |
| Host | | Host | | Internet | Host | | Host | | Internet
+--------+---+ +---+--------+ | +--------+---+ +---+--------+ |
| | / | | /
| | / | | /
+-+-----------+-+ \ +-+-----------+-+ \
| Service | \ | Service | \
| Provider | \ | Provider | \
| Router | | Service | Router | | Service
+-------+-------+ | Provider +-------+-------+ | Provider
| IPv6-only | Network | IPv6-only | Network
| Customer / | Customer /
| Internet Connection / | Internet Connection /
| / | /
+------+--------+ \ +------+--------+ \
| IPv6 | \ | IPv6 | \
| Customer Edge | \ | Transition CE | \
| Router | | | Router | |
+---+-------+---+ | +---+-------+---+ |
LAN A | | LAN B | End-User LAN A | | LAN B | End-User
-+----------------+- -+-----+-------------+- | Network(s) -+----------------+- -+-----+-------------+- | Network(s)
| | | | | | | |
+---+------+ +----+-----+ +-----+----+ | +---+------+ +----+-----+ +-----+----+ |
| IPv6-only| | IPv4-only| |IPv4/IPv6 | / | IPv6-only| | IPv4-only| |IPv4/IPv6 | /
| Host | | Host | | Host | / | Host | | Host | | Host | /
+----------+ +----------+ +----------+ / +----------+ +----------+ +----------+ /
Figure 1: Simplified Typical IPv6-only Access Network Figure 1: Simplified Typical IPv6-Only Access Network
This document covers a set of IP transition techniques required when This document covers a set of IP transition techniques required when
ISPs have, or want to have, an IPv6-only access network. This is a ISPs have, or want to have, an IPv6-only access network. This is a
common situation when sufficient IPv4 addresses are no longer common situation when sufficient IPv4 addresses are no longer
available for every possible customer and device, causing IPv4 available for every possible customer and device, which causes IPv4
addresses to become prohibitively expensive. This, in turn, may addresses to become prohibitively expensive. This, in turn, may
result in service providers provisioning IPv6-only WAN access. At result in service providers provisioning IPv6-only WAN access. At
the same time, they need to ensure that both IPv4-only and IPv6-only the same time, they need to ensure that both IPv4-only and IPv6-only
devices and applications in the customer networks can still reach devices and applications in the customer networks can still reach
IPv4-only devices and applications in the Internet. IPv4-only devices and applications on the Internet.
This document specifies the IPv4 service continuity mechanisms to be This document specifies the IPv4 service continuity mechanisms to be
supported by an IPv6 Transition CE Router, and relevant provisioning supported by an IPv6 Transition CE Router and relevant provisioning
or configuration information differences from [RFC7084]. or configuration information differences from [RFC7084].
This document is not a recommendation for service providers to use This document is not a recommendation for service providers to use
any specific transition mechanism. any specific transition mechanism.
Automatic provisioning of more complex topology than a single router Automatic provisioning of more complex topology than a single router
with multiple LAN interfaces may be handled by means of HNCP with multiple LAN interfaces may be handled by means of the Home
[RFC7788] (Home Networking Control Protocol), which is out of the Networking Control Protocol (HNCP) [RFC7788], which is out of the
scope of this document. scope of this document.
Since it is impossible to know prior to sale which transition Since it is impossible to know prior to sale which transition
mechanism a device will need over its lifetime, an IPv6 Transition CE mechanism a device will need over its lifetime, an IPv6 Transition CE
Router intended for the retail market MUST support all the IPv4aaS Router intended for the retail market MUST support all the IPv4aaS
transition mechanisms listed in this document. Service providers who transition mechanisms listed in this document. Service providers
specify feature sets for the IPv6 Transition CE Router, may define a that specify feature sets for the IPv6 Transition CE Router may
different set of features than those included in this document, for define a different set of features from those included in this
example supporting only some of the transition mechanisms enumerated document, for example, features that support only some of the
in this document. transition mechanisms enumerated in this document.
A complete description of "Usage Scenarios" and "End-User Network Appendices A and B contain a complete description of the usage
Architecture" is provided in Annexes A and B, respectively, which scenarios and end-user network architecture, respectively. These
together with [RFC7084], will facilitate the reader to have a clearer appendices, along with [RFC7084], will facilitate a clearer
understanding of this document. understanding of this document.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Terminology 2. Terminology
This document uses the same terms as in [RFC7084], with minor This document uses the same terms as in [RFC7084], with minor
clarifications. clarifications.
"IPv4aaS" stands for "IPv4 as-a-Service", meaning transition "IPv4aaS" stands for "IPv4-as-a-Service", meaning transition
technologies for delivering IPv4 in IPv6-only connectivity. technologies for delivering IPv4 in IPv6-only connectivity.
The term "IPv6 transition Customer Edge Router with IPv4aaS" The term "IPv6 transition Customer Edge Router with IPv4aaS"
(shortened as "IPv6 Transition CE Router") is defined as an "IPv6 (shortened as "IPv6 Transition CE Router") is defined as an IPv6
Customer Edge Router" that provides features for the delivery of IPv4 Customer Edge Router that provides features for the delivery of IPv4
services over an IPv6-only WAN network, including IPv6-IPv4 services over an IPv6-only WAN network, including IPv6-IPv4
communications. communications.
The "WAN Interface" term used across this document, defines an IPv6 The term "WAN Interface" as used in this document is defined as an
Transition CE Router attachment to an IPv6-only link used to provide IPv6 Transition CE Router attachment to an IPv6-only link used to
connectivity to a service provider network, including link Internet- provide connectivity to a service provider network, including link
layer (or higher layers) "tunnels", such as IPv4-in-IPv6 tunnels. Internet-layer (or higher layers) tunnels, such as IPv4-in-IPv6
tunnels.
3. Requirements 3. Requirements
The IPv6 Transition CE Router MUST comply with [RFC7084] (Basic The IPv6 Transition CE Router MUST comply with [RFC7084] ("Basic
Requirements for IPv6 Customer Edge Routers) and this document adds Requirements for IPv6 Customer Edge Routers"). This document adds
new requirements, as described in the following sub-sections. new requirements, as described in the following subsections.
3.1. LAN-Side Configuration 3.1. LAN-Side Configuration
A new LAN requirement is added, which in fact is common in regular A new LAN requirement is added, which is, in fact, common in regular
IPv6 Transition CE Routers, and it is required by most of the IPv6 Transition CE Routers, and is required by most of the transition
transition mechanisms: mechanisms:
L-1: The IPv6 Transition CE Router MUST implement a DNS proxy as L-1: The IPv6 Transition CE Router MUST implement a DNS proxy as
described in [RFC5625] (DNS Proxy Implementation Guidelines). described in [RFC5625] ("DNS Proxy Implementation Guidelines").
3.2. Transition Technologies Support for IPv4 Service Continuity (IPv4 3.2. Transition Technologies Support for IPv4 Service Continuity (IPv4-
as-a-Service - IPv4aaS) as-a-Service)
The main target of this document is the support of IPv6-only WAN The main target of this document is the support of IPv6-only WAN
access. To enable legacy IPv4 functionality, this document also access. To enable legacy IPv4 functionality, this document also
includes the support of IPv4-only devices and applications in the includes the support of IPv4-only devices and applications in the
customers LANs, as well as IPv4-only services on the Internet. Thus, customer LANs, as well as IPv4-only services on the Internet. Thus,
both IPv4-only and the IPv6-only devices in the customer-side LANs of both IPv4-only and IPv6-only devices in the customer-side LANs of the
the IPv6 Transition CE Router are able to reach the IPv4-only IPv6 Transition CE Router are able to reach the IPv4-only services.
services.
Note that this document is only configuring the IPv4aaS in the IPv6 Note that this document only configures IPv4aaS in the IPv6
Transition CE Router itself, and not forwarding such information to Transition CE Router itself; it does not forward such information to
devices attached to the LANs, so the WAN configuration, availability devices attached to the LANs. Thus, the WAN configuration and
of native IPv4 or IPv4aaS, is transparent for them. availability of native IPv4 or IPv4aaS are transparent for the
devices attached to the LANs.
This document takes no position on simultaneous operation of one or This document takes no position on simultaneous operation of one or
several transition mechanisms and/or native IPv4. several transition mechanisms and/or native IPv4.
In order to seamlessly provide IPv4 service continuity in the In order to seamlessly provide IPv4 service continuity in the
customer LANs, and allow automated IPv6 transition mechanism customer LANs and allow automated IPv6 transition mechanism
provisioning, the following general transition requirements are provisioning, the following general transition requirements are
defined. defined.
General transition requirements: General transition requirements:
TRANS-1: The IPv6 Transition CE Router MUST support the DHCPv6 S46 TRANS-1: The IPv6 Transition CE Router MUST support the DHCPv6 S46
priority options described in [RFC8026] (Unified IPv4-in- priority options described in [RFC8026] ("Unified IPv4-in-
IPv6 Softwire Customer Premises Equipment (CPE): A IPv6 Softwire Customer Premises Equipment (CPE): A
DHCPv6-Based Prioritization Mechanism). DHCPv6-Based Prioritization Mechanism").
TRANS-2: The IPv6 Transition CE Router MUST have a GUI and either a TRANS-2: The IPv6 Transition CE Router MUST have a GUI and either a
CLI or API (or both) to manually enable/disable each of the CLI or API (or both) to manually enable/disable each of the
supported transition mechanisms. supported transition mechanisms.
TRANS-3: If an IPv6 Transition CE Router supports more than one LAN TRANS-3: If an IPv6 Transition CE Router supports more than one LAN
subnet, the IPv6 Transition CE Router MUST allow subnet, the IPv6 Transition CE Router MUST allow
appropriate subnetting and configuration of the address appropriate subnetting and configuration of the address
space among the several interfaces. In some transition space among several interfaces. In some transition
mechanisms, this may require differentiating mappings/ mechanisms, this may require differentiating mappings/
translations on a per-interface basis. translations on a per-interface basis.
In order to allow the service provider to disable all the transition In order to allow the service provider to disable all the transition
mechanisms and/or choose the most convenient one, the IPv6 Transition mechanisms and/or choose the most convenient one, the IPv6 Transition
CE Router MUST follow the following configuration steps: CE Router MUST follow the following configuration steps:
CONFIG-1: Request the relevant configuration options for each CONFIG-1: Request the relevant configuration options for each
supported transition mechanisms, which MUST remain supported transition mechanisms, which MUST remain
disabled at this step. disabled at this step.
CONFIG-2: Following Section 1.4 of [RFC8026], MUST check for a valid CONFIG-2: Following the steps in Section 1.4 of [RFC8026], MUST
match in OPTION_S46_PRIORITY, which allows enabling/ check for a valid match in OPTION_S46_PRIORITY, which
disabling a transition mechanism. allows enabling/disabling a transition mechanism.
CONFIG-3: Keep disabled all the transition mechanisms if no match is CONFIG-3: Keep disabled all the transition mechanisms if no match is
found between the priority list and the candidate list, found between the priority list and the candidate list,
unless a NAT64 prefix has been configured, in which case, unless a NAT64 [RFC6146] prefix has been configured, in
464XLAT MUST be enabled. which case, 464XLAT [RFC6877] MUST be enabled.
Because 464XLAT has not DHCPv6 configuration options, it can't be Because 464XLAT has no DHCPv6 configuration options, it can't
included, at the time being, in the OPTION_S46_PRIORITY. In the currently be included in the OPTION_S46_PRIORITY. In the future, an
future, an update of [RFC8026] or a NAT64 DHCPv6 configuration update of [RFC8026] or a NAT64 DHCPv6 configuration option may enable
option, may enable it. Meanwhile, if an operator provides 464XLAT, it. Meanwhile, if an operator provides 464XLAT, it needs to ensure
it needs to ensure that OPTION_S46_PRIORITY is not sent for any other that OPTION_S46_PRIORITY is not sent for any other transition
transition mechanism to the relevant customers. mechanism to the relevant customers.
The following sections describe the requirements for supporting each The following subsections describe the requirements for supporting
one of the transition mechanisms. An IPv6 Transition CE Router each one of the transition mechanisms. An IPv6 Transition CE Router
intended for the retail market MUST support all of them. intended for the retail market MUST support all of them.
3.2.1. 464XLAT 3.2.1. 464XLAT
464XLAT [RFC6877] is a technique to provide IPv4 service over an 464XLAT [RFC6877] is a technique to provide IPv4 service over an
IPv6-only access network without encapsulation. This architecture IPv6-only access network without encapsulation. This architecture
assumes a NAT64 [RFC6146] (Stateful NAT64: Network Address and assumes a Stateful NAT64 [RFC6146] function deployed at the service
Protocol Translation from IPv6 Clients to IPv4 Servers) function provider or a third-party network.
deployed at the service provider or a third-party network.
The IPv6 Transition CE Router MUST support CLAT functionality The IPv6 Transition CE Router MUST support customer-side translator
[RFC6877] if intended for the retail market. If 464XLAT is (CLAT) functionality [RFC6877] if intended for the retail market. If
supported, it MUST be implemented according to [RFC6877]. The 464XLAT is supported, it MUST be implemented according to [RFC6877].
following IPv6 Transition CE Router requirements also apply: The following IPv6 Transition CE Router requirements also apply.
464XLAT requirements: 464XLAT requirements:
464XLAT-1: Unless a dedicated /64 prefix has been acquired, either 464XLAT-1: Unless a dedicated /64 prefix has been acquired, either
using DHCPv6-PD [RFC8415] (IPv6 Prefix Options for by using DHCPv6-PD (Dynamic Host Configuration Protocol
DHCPv6) or by alternative means, the IPv6 Transition CE for IPv6 Prefix Delegation) or by alternative means, the
Router MUST perform IPv4 Network Address Translation IPv6 Transition CE Router MUST perform IPv4 Network
(NAT) on IPv4 traffic translated using the CLAT. Address Translation (NAT) on IPv4 traffic translated
using the CLAT.
464XLAT-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF 464XLAT-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
[RFC6970] (UPnP Internet Gateway Device - Port Control [RFC6970] ("Universal Plug and Play (UPnP) Internet
Protocol Interworking Function). Gateway Device - Port Control Protocol Interworking
Function (IGD-PCP IWF)").
464XLAT-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE 464XLAT-3: If the Port Control Protocol (PCP) [RFC6887] is
Router MUST also implement [RFC7291] (DHCP Options for implemented, the IPv6 Transition CE Router MUST also
the PCP). Following [RFC6887], if no PCP server is implement [RFC7291] ("DHCP Options for the Port Control
configured, the IPv6 Transition CE Router MAY verify if Protocol (PCP)"). Following [RFC6887], if no PCP server
the default gateway, or the NAT64 is the PCP server. The is configured, the IPv6 Transition CE Router MAY verify
IPv6 Transition CE Router MUST use plain IPv6 mode (i.e., if the default gateway or the NAT64 is the PCP server.
no IPv4-in-IPv6 encapsulation is used) to send PCP The IPv6 Transition CE Router MUST use plain IPv6 mode
(i.e., not IPv4-in-IPv6 encapsulation) to send PCP
requests to the server. requests to the server.
464XLAT-4: The IPv6 Transition CE Router MUST implement [RFC7050] 464XLAT-4: The IPv6 Transition CE Router MUST implement [RFC7050]
(Discovery of the IPv6 Prefix Used for IPv6 Address ("Discovery of the IPv6 Prefix Used for IPv6 Address
Synthesis) in order to discover the PLAT-side translation Synthesis") in order to discover the provider-side
IPv4 and IPv6 prefix(es)/suffix(es). translator (PLAT) translation IPv4 and IPv6
prefix(es)/suffix(es).
464XLAT-5: If PCP is implemented, the IPv6 Transition CE Router MUST 464XLAT-5: If PCP is implemented, the IPv6 Transition CE Router MUST
follow [RFC7225] (Discovering NAT64 IPv6 Prefixes Using follow [RFC7225] ("Discovering NAT64 IPv6 Prefixes Using
the PCP), in order to learn the PLAT-side translation the Port Control Protocol (PCP)") in order to learn the
IPv4 and IPv6 prefix(es)/suffix(es) used by an upstream PLAT-side translation IPv4 and IPv6 prefix(es)/suffix(es)
PCP-controlled NAT64 device. used by an upstream PCP-controlled NAT64 device.
464XLAT-6: The priority for the NAT64 prefix, in case the network 464XLAT-6: If the network provides several choices for the
provides several choices, MUST be: 1) [RFC7225], 2) discovery/learning of the NAT64 prefix, the priority to
[RFC7050]. use one or the other MUST follow this order: 1) [RFC7225]
and 2) [RFC7050].
The NAT64 prefix could be discovered by means of [RFC7050] only in The NAT64 prefix could be discovered by means of the method defined
the case the service provider uses DNS64 [RFC6147]. It may be the in [RFC7050] only if the service provider uses DNS64 [RFC6147]. It
case that the service provider does not use or does not trust DNS64 may be the case that the service provider does not use or does not
[RFC6147] because the DNS configuration at the CE (or hosts behind trust DNS64 [RFC6147] because the DNS configuration at the CE (or
the CE) can be modified by the customer. In that case, the service hosts behind the CE) can be modified by the customer. In that case,
provider may opt to configure the NAT64 prefix by means of [RFC7225]. the service provider may opt to configure the NAT64 prefix by means
This can also be used if the service provider uses DNS64 [RFC6147]. of the option defined in [RFC7225]. This can also be used if the
service provider uses DNS64 [RFC6147].
3.2.2. Dual-Stack Lite (DS-Lite) 3.2.2. Dual-Stack Lite (DS-Lite)
Dual-Stack Lite [RFC6333] enables continued support for IPv4 DS-Lite [RFC6333] enables continued support for IPv4 services.
services. Dual-Stack Lite enables a broadband service provider to DS-Lite enables a broadband service provider to share IPv4 addresses
share IPv4 addresses among customers by combining two well-known among customers by combining two well-known technologies: IP in IP
technologies: IP in IP (IPv4-in-IPv6) and Network Address Translation (IPv4-in-IPv6) and Network Address Translation (NAT). It is expected
(NAT). It is expected that DS-Lite traffic is forwarded over the that DS-Lite traffic is forwarded over the IPv6 Transition CE
IPv6 Transition CE Router's native IPv6 WAN interface, and not Router's native IPv6 WAN interface and not encapsulated in another
encapsulated in another tunnel. tunnel.
The IPv6 Transition CE Router MUST implement DS-Lite B4 functionality The IPv6 Transition CE Router MUST implement DS-Lite B4 functionality
[RFC6333] if intended for the retail market. If DS-Lite is [RFC6333] if intended for the retail market. If DS-Lite is
supported, it MUST be implemented according to [RFC6333]. The supported, it MUST be implemented according to [RFC6333]. The
following IPv6 Transition CE Router requirements also apply: following IPv6 Transition CE Router requirements also apply.
DS-Lite requirements: DS-Lite requirements:
DSLITE-1: The IPv6 Transition CE Router MUST support configuration DSLITE-1: The IPv6 Transition CE Router MUST support configuration
of DS-Lite via the DS-Lite DHCPv6 option [RFC6334] (DHCPv6 of DS-Lite via the DS-Lite DHCPv6 option [RFC6334]
Option for Dual-Stack Lite). The IPv6 Transition CE ("Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
Option for Dual-Stack Lite"). The IPv6 Transition CE
Router MAY use other mechanisms to configure DS-Lite Router MAY use other mechanisms to configure DS-Lite
parameters. Such mechanisms are outside the scope of this parameters. Such mechanisms are outside the scope of this
document. document.
DSLITE-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF DSLITE-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
[RFC6970] (UPnP Internet Gateway Device - Port Control [RFC6970].
Protocol Interworking Function).
DSLITE-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE DSLITE-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE
Router SHOULD implement [RFC7291] (DHCP Options for the Router SHOULD implement [RFC7291]. If PCP [RFC6887] is
PCP). If PCP [RFC6887] is implemented and a PCP server is implemented and a PCP server is not configured, the IPv6
not configured, the IPv6 Transition CE Router MUST assume, Transition CE Router MUST assume, by default, that the
by default, that the AFTR is the PCP server. The IPv6 Address Family Transition Router (AFTR, commonly called
Transition CE Router MUST use plain IPv6 mode (i.e., no "CGN" - Carrier-Grade NAT) is the PCP server. The IPv6
IPv4-in-IPv6 encapsulation is used) to send PCP requests
to the server. The term "default" above is to be Transition CE Router MUST use plain IPv6 mode (i.e., not
interpreted as pertaining to a configuration as applied by IPv4-in-IPv6 encapsulation) to send PCP requests to the
a vendor, prior to the administrator changing it for its server. The term "default" above is to be interpreted as
initial activation. pertaining to a configuration as applied by a vendor prior
to the administrator changing it for its initial
activation.
DSLITE-4: The IPv6 Transition CE Router MUST NOT perform IPv4 DSLITE-4: The IPv6 Transition CE Router MUST NOT perform IPv4
Network Address Translation (NAT) on IPv4 traffic Network Address Translation (NAT) on IPv4 traffic
encapsulated using DS-Lite [RFC6333]. encapsulated using DS-Lite [RFC6333].
3.2.3. Lightweight 4over6 (lw4o6) 3.2.3. Lightweight 4over6 (lw4o6)
lw4o6 [RFC7596] specifies an extension to DS-Lite which moves the lw4o6 [RFC7596] specifies an extension to DS-Lite that moves the NAPT
NAPT function from the DS-Lite tunnel concentrator to the tunnel function from the DS-Lite tunnel concentrator to the tunnel client
client located in the IPv6 Transition CE Router, removing the located in the IPv6 Transition CE Router, removing the requirement
requirement for a CGN (Carrier Grade NAT, AFTR - Address Family for an AFTR (CGN) function in the tunnel concentrator and reducing
Transition Router) function in the tunnel concentrator and reducing
the amount of centralized state. the amount of centralized state.
The IPv6 Transition CE Router MUST implement lwB4 functionality The IPv6 Transition CE Router MUST implement lwB4 functionality
[RFC7596] if intended for the retail market. If DS-Lite is [RFC7596] if intended for the retail market. If DS-Lite is
implemented, lw4o6 SHOULD be implemented as well. If lw4o6 is implemented, lw4o6 SHOULD be implemented as well. If lw4o6 is
supported, it MUST be implemented according to [RFC7596]. The supported, it MUST be implemented according to [RFC7596]. The
following IPv6 Transition CE Router requirements also apply: following IPv6 Transition CE Router requirements also apply.
lw4o6 requirements: lw4o6 requirements:
LW4O6-1: The IPv6 Transition CE Router MUST support configuration of LW4O6-1: The IPv6 Transition CE Router MUST support configuration of
lw4o6 via the lw4o6 DHCPv6 options [RFC7598] (DHCPv6 lw4o6 via the lw4o6 DHCPv6 options [RFC7598] ("DHCPv6
Options for Configuration of Softwire Address and Port- Options for Configuration of Softwire Address and Port-
Mapped Clients). The IPv6 Transition CE Router MAY use Mapped Clients"). The IPv6 Transition CE Router MAY use
other mechanisms to configure lw4o6 parameters. Such other mechanisms to configure lw4o6 parameters. Such
mechanisms are outside the scope of this document. mechanisms are outside the scope of this document.
LW4O6-2: The IPv6 Transition CE Router MUST support the DHCPv4-over- LW4O6-2: The IPv6 Transition CE Router MUST support the DHCPv4-over-
DHCPv6 (DHCP 4o6) transport described in [RFC7341] (DHCPv4- DHCPv6 (DHCP 4o6) transport described in [RFC7341]
over-DHCPv6 Transport). ("DHCPv4-over-DHCPv6 (DHCP 4o6) Transport").
LW4O6-3: The IPv6 Transition CE Router MAY support Dynamic LW4O6-3: The IPv6 Transition CE Router MAY support Dynamic
Allocation of Shared IPv4 Addresses as described in Allocation of Shared IPv4 Addresses as described in
[RFC7618] (Dynamic Allocation of Shared IPv4 Addresses). [RFC7618] ("Dynamic Allocation of Shared IPv4 Addresses").
3.2.4. MAP-E 3.2.4. MAP-E
MAP-E [RFC7597] is a mechanism for transporting IPv4 packets across Mapping of Address and Port with Encapsulation (MAP-E) [RFC7597] is a
an IPv6 network using IP encapsulation, including an algorithmic mechanism for transporting IPv4 packets across an IPv6 network using
mechanism for mapping between IPv6 and IPv4 addresses. IP encapsulation. MAP-E includes an algorithmic mechanism for
mapping between IPv6 and IPv4 addresses.
The IPv6 Transition CE Router MUST support MAP-E CE functionality The IPv6 Transition CE Router MUST support MAP-E CE functionality
[RFC7597] if intended for the retail market. If MAP-E is supported, [RFC7597] if intended for the retail market. If MAP-E is supported,
it MUST be implemented according to [RFC7597]. The following IPv6 it MUST be implemented according to [RFC7597]. The following IPv6
Transition CE Router requirements also apply: Transition CE Router requirements also apply.
MAP-E requirements: MAP-E requirements:
MAPE-1: The IPv6 Transition CE Router MUST support configuration of MAPE-1: The IPv6 Transition CE Router MUST support configuration of
MAP-E via the MAP-E DHCPv6 options [RFC7598] (DHCPv6 Options MAP-E via the MAP-E DHCPv6 options [RFC7598]. The IPv6
for Configuration of Softwire Address and Port-Mapped Transition CE Router MAY use other mechanisms to configure
Clients). The IPv6 Transition CE Router MAY use other MAP-E parameters. Such mechanisms are outside the scope of
mechanisms to configure MAP-E parameters. Such mechanisms this document.
are outside the scope of this document.
MAPE-2: The IPv6 Transition CE Router MAY support Dynamic Allocation MAPE-2: The IPv6 Transition CE Router MAY support Dynamic Allocation
of Shared IPv4 Addresses as described in [RFC7618] (Dynamic of Shared IPv4 Addresses as described in [RFC7618].
Allocation of Shared IPv4 Addresses).
3.2.5. MAP-T 3.2.5. MAP-T
MAP-T [RFC7599] is a mechanism similar to MAP-E, differing from it in MAP-T [RFC7599] is a mechanism similar to MAP-E, differing from it in
that MAP-T uses IPv4-IPv6 translation, instead of encapsulation, as that MAP-T uses IPv4-IPv6 translation, instead of encapsulation, as
the form of IPv6 domain transport. the form of IPv6 domain transport.
The IPv6 Transition CE Router MUST support MAP-T CE functionality The IPv6 Transition CE Router MUST support MAP-T CE functionality
[RFC7599] if intended for the retail market. If MAP-T is supported, [RFC7599] if intended for the retail market. If MAP-T is supported,
it MUST be implemented according to [RFC7599]. The following IPv6 it MUST be implemented according to [RFC7599]. The following IPv6
Transition CE Router requirements also apply: Transition CE Router requirements also apply.
MAP-T requirements: MAP-T requirements:
MAPT-1: The IPv6 Transition CE Router MUST support configuration of MAPT-1: The IPv6 Transition CE Router MUST support configuration of
MAP-T via the MAP-T DHCPv6 options [RFC7598] (DHCPv6 Options MAP-T via the MAP-T DHCPv6 options [RFC7598]. The IPv6
for Configuration of Softwire Address and Port-Mapped Transition CE Router MAY use other mechanisms to configure
Clients). The IPv6 Transition CE Router MAY use other MAP-T parameters. Such mechanisms are outside the scope of
mechanisms to configure MAP-T parameters. Such mechanisms this document.
are outside the scope of this document.
MAPT-2: The IPv6 Transition CE Router MAY support Dynamic Allocation MAPT-2: The IPv6 Transition CE Router MAY support Dynamic Allocation
of Shared IPv4 Addresses as described in [RFC7618] (Dynamic of Shared IPv4 Addresses as described in [RFC7618].
Allocation of Shared IPv4 Addresses).
4. IPv4 Multicast Support 4. IPv4 Multicast Support
Existing IPv4 deployments support IPv4 multicast for services such as Existing IPv4 deployments support IPv4 multicast for services such as
IPTV. In the transition phase, it is expected that multicast IPTV. In the transition phase, it is expected that multicast
services will still be provided using IPv4 to the customer LANs. services will still be provided using IPv4 to the customer LANs.
If the IPv6 Transition CE Router supports delivery of IPv4 multicast If the IPv6 Transition CE Router supports delivery of IPv4 multicast
services, then it MUST support [RFC8114] (Delivery of IPv4 Multicast services, then it MUST support [RFC8114] ("Delivery of IPv4 Multicast
Services to IPv4 Clients over an IPv6 Multicast Network) and Services to IPv4 Clients over an IPv6 Multicast Network") and
[RFC8115] (DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6 [RFC8115] ("DHCPv6 Option for IPv4-Embedded Multicast and Unicast
Prefixes). IPv6 Prefixes").
5. UPnP Support 5. UPnP Support
If the UPnP WANIPConnection:2 service [UPnP-WANIPC] is enabled on a If the UPnP WANIPConnection:2 service [UPnP-WANIPC][OCF-IGD] is
CE router, but cannot be associated with an IPv4 interface enabled on a CE router, but cannot be associated with an IPv4
established by an IPv4aaS mechanism or cannot determine which ports interface established by an IPv4aaS mechanism or cannot determine
are available, an AddPortMapping() or AddAnyPortMapping() action MUST which ports are available, an AddPortMapping() or AddAnyPortMapping()
be rejected with error code 729 "ConflictWithOtherMechanisms". Port action MUST be rejected with error code 729
availability could be determined through PCP or access to a ("ConflictWithOtherMechanisms"). Port availability could be
configured port set (if the IPv4aaS mechanism limits the available determined through PCP or access to a configured port set (if the
ports). IPv4aaS mechanism limits the available ports).
An AddPortMapping() request for a port that is not available MUST An AddPortMapping() request for a port that is not available MUST
result in "ConflictInMappingEntry". result in "ConflictInMappingEntry".
An AddAnyPortMapping() request for a port that is not available An AddAnyPortMapping() request for a port that is not available
SHOULD result in a successful mapping with an alternative SHOULD result in a successful mapping with an alternative
"NewReservedPort" value from within the configured port set range, or "NewReservedPort" value from within the configured port set range or
as assigned by PCP as per [RFC6970], Section 5.6.1. as assigned by PCP as per Section 5.6.1 of [RFC6970].
Note that IGD:1 and its WANIPConnection:1 service have been Note that IGD:1 and its WANIPConnection:1 service have been
deprecated by OCF (Open Connectivity Foundation). deprecated by OCF (Open Connectivity Foundation) [OCF-IGD].
6. Comparison to RFC7084 6. Comparison to RFC 7084
This document doesn't include support for 6rd [RFC5969], because it This document doesn't include support for 6rd [RFC5969] because it is
is an IPv6-in-IPv4 tunneling. an IPv6-in-IPv4 tunneling.
Regarding DS-LITE [RFC6333], this document includes slightly Regarding DS-LITE [RFC6333], this document includes slightly
different requirements, related to the support of PCP [RFC6887], IGD- different requirements related to the support of PCP [RFC6887],
PCP IWF [RFC6970] and the prioritization of the transition IGD-PCP IWF [RFC6970], and the prioritization of the transition
mechanisms, including dual-stack. mechanisms, including dual-stack.
7. Code Considerations 7. Code Considerations
At the time of this writing, one of the apparent main issues for At the time of this writing, one of the apparent main issues for
vendors to include new functionalities, such as support for new vendors with regard to including new functionalities, such as support
transition mechanisms, is the lack of space in the flash (or for new transition mechanisms, is the lack of space in the flash (or
equivalent) memory. However, it has been confirmed from existing equivalent) memory. However, it has been confirmed from existing
open source implementations (OpenWRT/LEDE, Linux, VPP, others), that open-source implementations (e.g., OpenWRT/LEDE, Linux, and VPP) that
adding the support for the new transition mechanisms, requires around adding the support for the new transition mechanisms requires around
10-12 Kbytes, because most of the code base is shared among several 10-12 KBs because most of the code base is shared among several
transition mechanisms, which are already supported by [RFC7084]. A transition mechanisms, which are already supported by [RFC7084]. A
single data plane is common to all them, which typically means, in single data plane is common to all of them, which typically means, in
popular CEs already in the market [OpenWRT], the new required code is popular CEs already in the market [OpenWRT], the new required code is
only about 0.15% of the total existing code size. only about 0.15% of the total existing code size.
In general, the new requirements don't have extra cost in terms of In general, the new requirements don't have extra cost in terms of
RAM memory, nor other hardware requirements such as more powerful RAM memory, nor other hardware requirements such as more powerful
CPUs, if compared to the cost of NAT44 code, so existing hardware CPUs, if compared to the cost of NAT44 code. Thus, existing hardware
should be able to support all them with minimal impact. should be able to support all of them with minimal impact.
The other issue seems to be the cost of developing the code for those The other issue seems to be the cost of developing the code for those
new functionalities. However, at the time of writing this document, new functionalities. However, at the time of writing this document,
it has been confirmed that there are several open source versions of it has been confirmed that there are several open-source versions of
the required code for supporting all the new transition mechanisms, the required code for supporting all the new transition mechanisms,
and several vendors already have implementations and provide it to and several vendors already have implementations and provided them to
ISPs, so the development cost is negligible, and only integration and ISPs. Therefore, the development cost is negligible, and only
testing cost may become an issue. integration and testing cost may become an issue.
Finally, in some cases, operators supporting several transition Finally, in some cases, operators supporting several transition
mechanisms may need to consider training costs for staff in all the mechanisms may need to consider training costs for staff in all the
techniques for their operation and management, even if this is not techniques for the operation and management of these mechanisms, even
directly caused by supporting this document, but because the business if the costs are not directly caused by supporting this document but
decisions behind that. because of business decisions.
8. Security Considerations 8. Security Considerations
The IPv6 Transition CE Router must comply with the Security The IPv6 Transition CE Router must comply with the Security
Considerations as stated in [RFC7084], as well as those stated by Considerations in [RFC7084] as well as those for each transition
each transition mechanism implemented by the IPv6 Transition CE mechanism implemented by the IPv6 Transition CE Router.
Router.
As described in [RFC8026] and [RFC8415] Security Consideration As described in the Security Considerations of [RFC8026] and
sections, there are generic DHCP security issues, which in the case [RFC8415], there are generic DHCP security issues, which, in the case
of this document means that malicious nodes may alter the priority of of this document, mean that malicious nodes may alter the priority of
the transition mechanisms. the transition mechanisms.
Access network architecture for securing DHCP within the access Access network architecture for securing DHCP within the access
network is out of scope of this document. Securing DHCP in the LAN network is out of scope for this document. Securing DHCP in the LAN
is also not in scope. DHCP packets MUST NOT be forwarded between LAN is also not in scope. DHCP packets MUST NOT be forwarded between LAN
and WAN interfaces of an IPv6 Transition CE router. and WAN interfaces of an IPv6 Transition CE Router.
9. IANA Considerations 9. IANA Considerations
This document does not have any new specific IANA considerations. This document has no IANA actions.
10. Acknowledgements
Thanks to Mikael Abrahamsson, Fred Baker, Mohamed Boucadair, Brian
Carpenter, Ian Farrer, Lee Howard, Richard Patterson, Barbara Stark,
Ole Troan, James Woodyatt, Lorenzo Colitti and Alejandro D'Egidio,
for their review and comments in this and/or previous versions of
this document, as well as to the Last Call reviewers by the Ops-dir
(Dan Romascanu), Sec-dir (Christian Huitema), Rtg-dir (Daniele
Ceccarelli), Tsv-art (Martin Stiemerling), Gen-art (Matthew Miller)
and IESG (Alissa Cooper, Benjamin Kaduk, Suresh Krishnan, Ben
Campbell, Spencer Dawkins, Mirja Kuhlewind, and Adam Roach).
11. Annex A: Usage Scenarios
The situation previously described, where there is ongoing IPv6
deployment and lack of IPv4 addresses, is not happening at the same
pace in every country, and even within every country, for every ISP.
For different technical, financial, commercial/marketing and socio-
economic reasons, each network is transitioning at their own pace;
the global transition timings cannot be reliably estimated.
Different studies (for example [IPv6Survey]) also show that the IPv6
deployment is a changing situation. In a single country, not all
operators will necessarily provide IPv6 support. Consumers may also
switch ISPs, and use the same IPv6 Transition CE Router with either
an ISP that provides IPv4-only or an ISP that provides IPv6 with
IPv4aaS.
So, to cover all those evolving situations, an IPv6 Transition CE
Router is required, at least from the perspective of the transition
support.
Moreover, because some services will remain IPv4-only for an
undetermined time, and some service providers will remain IPv4-only
for an undetermined period of time, IPv4 will be needed for an
undetermined period of time. There will be a need for CEs with
support "IPv4 as-a-Service" for an undetermined period of time.
This document, based on those premises, ensures that the IPv6
Transition CE Router allows the continued transition from networks
that today may provide access with dual-stack or IPv6-in-IPv4, as
described in [RFC7084], and as an "extension" to it, evolve to an
IPv6-only access with IPv4-as-a-Service.
Considering that situation and different possible usage cases, the
IPv6 Transition CE Router described in this document is expected to
be used typically, in residential/household, Small Office/Home Office
(SOHO) and Small/Medium Enterprise (SME). Common usage is any kind
of Internet access (web, email, streaming, online gaming, etc.) and
even more advanced requirements including inbound connections (IP
cameras, web, DNS, email, VPN, etc.).
The above is not intended to be a comprehensive list of all the
possible usage cases, just an overall view. In fact, combinations of
the above usages are also possible, as well as situations where the
same CE is used at different times in different scenarios or even
different with services providers that may use a different transition
mechanism.
The mechanisms for allowing inbound connections are "naturally"
available in any IPv6 router when using GUA (IPv6 Global Unicast
Addresses), unless they are blocked by firewall rules, which may
require some manual configuration.
However, in the case of IPv4aaS, because the usage of private
addresses and NAT and even depending on the specific transition
mechanism, inbound connections typically require some degree of more
complex manual configuration such as setting up a DMZ, virtual
servers, or port/protocol forwarding. In general, IPv4 CE Routers
already provide a GUI, CLI or API to manually configure them, or the
possibility to setup the CE in bridge mode, so another CE behind it
takes care of that. The requirements for that support are out of the
scope of this document.
It is not relevant who provides the IPv6 Transition CE Router. In
most of the cases it is the service provider, and in fact they are
responsible, typically, of provisioning/managing at least the WAN
side. Commonly, the user has access to configure the LAN interfaces,
firewall, DMZ, and many other features. However, in many cases, the
user must supply or may replace the IPv6 Transition CE Router. This
underscores the importance of the IPv6 Transition CE Routers
fulfilling the same requirements defined in this document.
The IPv6 Transition CE Router described in this document is not
intended for usage in other scenarios such as large Enterprises, Data
Centers, Content Providers, etc. So even if the documented
requirements meet their needs, they may have additional requirements,
which are out of the scope of this document.
12. Annex B: End-User Network Architecture
According to the descriptions in the preceding sections, an end-user
network will likely support both IPv4 and IPv6. It is not expected
that an end-user will change their existing network topology with the
introduction of IPv6. There are some differences in how IPv6 works
and is provisioned; these differences have implications for the
network architecture.
A typical IPv4 end-user network consists of a "plug and play" router
with NAT functionality and a single link upstream, connected to the
service provider network.
From the perspective of an "IPv4 user" behind an IPv6 transition
Customer Edge Router with IPv4aaS, this doesn't change.
However, while a typical IPv4 NAT deployment by default blocks all
incoming connections and may allow opening of ports using a Universal
Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some
other firewall control protocol, in the case of an IPv6-only access
and IPv4aaS, that may not be feasible depending on specific
transition mechanism details. PCP (Port Control Protocol, [RFC6887])
may be an alternative solution.
Another consequence of using IPv4 private address space in the end-
user network is that it provides stable addressing; that is, it
doesn't change, even when you change service providers, and the
addresses are always usable even when the WAN interface is down or
the customer edge router has not yet been provisioned. In the case
of an IPv6-only access, private IPv4 addresses are also available if
the IPv4aaS transition mechanism keeps running the NAT interface
towards the LAN side when the WAN interface is down.
More advanced routers support dynamic routing (which learns routes
from other routers), and advanced end-users can build arbitrary,
complex networks using manual configuration of address prefixes
combined with a dynamic routing protocol. Once again, this is true
for both IPv4 and IPv6.
In general, the end-user network architecture for IPv6 should provide
equivalent or better capabilities and functionality than the current
IPv4 architecture.
The end-user network is a stub network, in the sense that is not
providing transit to other external networks. However, HNCP
[RFC7788] allows support for automatic provisioning of downstream
routers. Figure 2 illustrates the model topology for the end-user
network.
+---------------+ \
| Service | \
| Provider | \
| Router | | Service
+-------+-------+ | Provider
| IPv6-only | Network
| Customer /
| Internet Connection /
| /
+------+--------+ \
| IPv6 | \
| Customer Edge | \
| Router | |
+---+-------+---+ |
Network A | | Network B |
-+----------------+-+- -+---+-------------+- |
| | | | |
+---+------+ | +----+-----+ +-----+----+ |
| IPv6 | | | IPv4 | |IPv4/IPv6 | |
| Host | | | Host | | Host | |
+----------+ | +----------+ +----------+ | End-User
| | Network(s)
+------+--------+ |
| IPv6 | |
| Router | |
+------+--------+ |
Network C | |
-+-------------+--+- |
| | |
+---+------+ +----+-----+ |
| IPv6 | | IPv6 | /
| Host | | Host | /
+----------+ +----------+ /
Figure 2: An Example of a Typical End-User Network
This architecture describes the:
o Basic capabilities of the IPv6 Transition CE Router
o Provisioning of the WAN interface connecting to the service
provider
o Provisioning of the LAN interfaces
The IPv6 Transition CE Router may be manually configured in an
arbitrary topology with a dynamic routing protocol or using HNCP
[RFC7788]. Automatic provisioning and configuration is described for
a single IPv6 Transition CE Router only.
13. ANNEX C: Changes from -00
Section to be removed by RFC Editor. Significant updates are:
1. ID-Nits: IANA section.
2. ID-Nits: RFC7084 reference removed from Abstract.
3. This document no longer updates RFC7084.
4. UPnP section reworded.
5. "CE Router" changed to "IPv6 Transition CE Router".
6. Reduced text in Annex A.
14. ANNEX D: Changes from -01
Section to be removed by RFC Editor. Significant updates are:
1. TRANS requirements reworked in order to increase operator control
and allow gradual transitioning from dual-stack to IPv6-only on
specific customers.
2. New TRANS requirement so all the supported transition mechanisms
are disabled by default, in order to facilitate the operator
management.
3. New TRANS requirement in order to allow turning on/off each
transition mechanism by the user.
4. Clarification on how to obtain multiple /64 for 464XLAT.
5. S46 priority update to RFC8026 for including 464XLAT and related
changes in several sections.
15. ANNEX E: Changes from -02
Section to be removed by RFC Editor. Significant updates are:
1. RFC8026 update removed, not needed with new approach.
2. TRANS and 464XLAT requirements reworded in order to match new
approach to allow operator control on each/all the transition
mechanisms.
3. Added text in 464XLAT to clarify the usage.
16. ANNEX F: Changes from -03
Section to be removed by RFC Editor. Significant updates are:
1. Several editorial changes across the document, specially TRANS
requirements.
2. DNS proxy MUST instead of SHOULD.
17. ANNEX G: Changes from -04
Section to be removed by RFC Editor. Significant updates are:
1. Removed G-1.
2. Added support for draft-pref64folks-6man-ra-pref64.
3. General text clarifications.
18. ANNEX H: Changes from -05
Section to be removed by RFC Editor. Significant updates are:
1. Reworded and shorter UPnP section and new informative reference.
2. New general transition requirement in case multiple public IPv4
prefixes are provided, so to run multiple instances according to
each specific transition mechanism.
3. General text clarifications.
19. ANNEX I: Changes from -06
Section to be removed by RFC Editor. Significant updates are:
1. Removed reference and text related to pref64folks-6man-ra-pref64.
2. General text clarifications.
20. ANNEX J: Changes from -07
Section to be removed by RFC Editor. Significant updates are:
1. Added text to UPnP section.
21. ANNEX K: Changes from -08, -09 and -10
Section to be removed by RFC Editor. Significant updates are:
1. Editorial edits.
22. ANNEX L: Changes from -11, -12, -13 and -14
Section to be removed by RFC Editor. Significant updates are:
1. Changes related to suggestions by Ops-dir, Sec-dir, Rtg-dir, Tsv-
art and Gen-art, as well as comments from IESG review.
2. IANA section removed as a consequence of the removal of the
inclusion of 464XLAT in the RFC8026 priority mechanism.
23. References 10. References
23.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",
BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009, BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009,
<https://www.rfc-editor.org/info/rfc5625>. <https://www.rfc-editor.org/info/rfc5625>.
skipping to change at page 23, line 15 skipping to change at page 16, line 15
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters, Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018, RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>. <https://www.rfc-editor.org/info/rfc8415>.
23.2. Informative References 10.2. Informative References
[IPv6Survey] [IPv6Survey]
Palet Martinez, J., "IPv6 Deployment Survey", January Palet Martinez, J., "Best Current Operational Practice for
2018, operators: IPv6 Prefix Assignment for end-customers --
persistent vs non-persistent and what size to choose",
January 2018,
<https://indico.uknof.org.uk/event/41/contribution/5/ <https://indico.uknof.org.uk/event/41/contribution/5/
material/slides/0.pdf>. material/slides/0.pdf>.
[OpenWRT] OpenWRT, "OpenWRT Packages", January 2018, [OCF-IGD] Open Connectivity Foundation, "Internet Gateway Device
<https://openwrt.org/packages/start>. (IGD) V 2.0", March 2015,
<https://openconnectivity.org/developer/specifications/
upnp-resources/upnp/internet-gateway-device-igd-v-2-0>.
[OpenWRT] OpenWRT, "Packages", <https://openwrt.org/packages/start>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking [RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <https://www.rfc-editor.org/info/rfc7788>. 2016, <https://www.rfc-editor.org/info/rfc7788>.
[UPnP-IGD] [UPnP-IGD]
UPnP Forum, "InternetGatewayDevice:2 Device Template UPnP Forum, "InternetGatewayDevice:2 Device Template
Version 1.01", December 2010, Version 1.01", December 2010, <http://upnp.org/specs/gw/
<http://upnp.org/specs/gw/igd2/>. UPnP-gw-InternetGatewayDevice-v2-Device.pdf>.
[UPnP-WANIPC] [UPnP-WANIPC]
UPnP Forum, "WANIPConnection:2 Service", December 2010, UPnP Forum, "WANIPConnection:2 Service", September 2010,
<http://upnp.org/specs/gw/ <http://upnp.org/specs/gw/
UPnP-gw-WANIPConnection-v2-Service.pdf>. UPnP-gw-WANIPConnection-v2-Service.pdf>.
Appendix A. Usage Scenarios
The situation of ongoing IPv6 deployment and a lack of IPv4 addresses
is not happening at the same pace in every country and even within
every country for every ISP. For different technical, financial,
commercial/marketing, and socio-economic reasons, each network is
transitioning at their own pace; the global transition timings cannot
be reliably estimated.
Different studies (for example, [IPv6Survey]) also show that IPv6
deployment is a changing situation. In a single country, not all
operators will necessarily provide IPv6 support. Consumers may also
switch ISPs and use the same IPv6 Transition CE Router with either an
ISP that provides IPv4-only or an ISP that provides IPv6 with
IPv4aaS.
So, to cover all those evolving situations, an IPv6 Transition CE
Router is required, at least from the perspective of transition
support.
Moreover, because some services and service providers will remain
IPv4-only for an undetermined period of time, IPv4 service continuity
is required. Thus, there is a need for CEs to support IPv4aaS
indefinitely.
Based on these premises, this document ensures that the IPv6
Transition CE Router allows the continued transition from networks
that today may provide access with dual-stack or IPv6-in-IPv4 (as
described in [RFC7084]) to networks that provide IPv6-only access
with IPv4aaS.
Considering that situation and different possible usage cases, the
IPv6 Transition CE Router described in this document is expected to
be used in residential/household; small office, home office (SOHO);
and small/medium enterprise (SME). Common usage is any kind of
Internet access (web, email, streaming, online gaming, etc.), and
more advanced requirements include inbound connections (IP cameras,
web, DNS, email, VPN, etc.).
The above is not intended to be a comprehensive list of all the
possible usage cases, just an overview. In fact, combinations of the
above usages are also possible, along with situations where the same
CE is used at different times in different scenarios or even with
different IPv4aaSes at different service providers.
The mechanisms for allowing inbound connections are naturally
available in any IPv6 router when using IPv6 Global Unicast Addresses
(GUAs), unless they are blocked by firewall rules, which may require
some manual configuration.
However, in the case of IPv4aaS, because of the usage of private IPv4
addresses and NAT and depending on the specific transition mechanism,
inbound connections typically require some degree of more complex
manual configuration, such as setting up a DMZ, setting up virtual
servers, or setting up port/protocol forwarding. In general, IPv4 CE
Routers already provide a GUI, CLI, or API to manually configure
them, or provide the possibility to set up the CE in bridge mode, so
another Router behind the original CE, takes care of inbound
connections. The requirements for that support are out of the scope
of this document.
Who provides the IPv6 Transition CE Router is not relevant. In most
cases, the service provider is responsible for provisioning/managing,
at least on the WAN side. Commonly, the user has access to configure
the LAN interfaces, firewall, DMZ, and many other features. However,
in many cases, the user must supply or may replace the IPv6
Transition CE Router. This underscores the importance of the IPv6
Transition CE Routers fulfilling the requirements defined in this
document.
The IPv6 Transition CE Router described in this document is not
intended for usage in other scenarios, such as large enterprises,
data centers, content providers, etc. Even if the documented
requirements meet their needs, they may have additional requirements,
which are out of the scope of this document.
Appendix B. End-User Network Architecture
An end-user network will likely support both IPv4 and IPv6 (see
Section 1 and Appendix A). It is not expected that end users will
change their existing network topology with the introduction of IPv6.
There are some differences in how IPv6 works and is provisioned;
these differences have implications for the network architecture.
A typical IPv4 end-user network consists of a "plug and play" router
with NAT functionality and a single link upstream, connected to the
service provider network.
From the perspective of an IPv4 user behind an IPv6 Transition CE
Router, this doesn't change.
However, while a typical IPv4 NAT deployment, by default, blocks all
incoming connections and may allow opening of ports using a Universal
Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD][OCF-IGD]
or some other firewall control protocol, in the case of an IPv6-only
access and IPv4aaS, that may not be feasible depending on specific
transition mechanism details. PCP [RFC6887] may be an alternative
solution.
Another consequence of using IPv4 private address space in the end-
user network is that it provides stable addressing; that is, it
doesn't change, even when you change service providers, and the
addresses are always usable even when the WAN interface is down or
the customer edge router has not yet been provisioned. In the case
of IPv6-only access, private IPv4 addresses are also available if the
IPv4aaS transition mechanism keeps running the NAT interface towards
the LAN side when the WAN interface is down.
More advanced routers support dynamic routing (which learns routes
from other routers), and advanced end users can build arbitrary,
complex networks using manual configuration of address prefixes
combined with a dynamic routing protocol. Once again, this is true
for both IPv4 and IPv6.
In general, the end-user network architecture for IPv6 should provide
equivalent or better capabilities and functionality than the current
IPv4 architecture.
The end-user network is a stub network in the sense that is not
providing transit to other external networks. However, HNCP
[RFC7788] allows support for automatic provisioning of downstream
routers. Figure 2 illustrates the model topology for the end-user
network.
+---------------+ \
| Service | \
| Provider | \
| Router | | Service
+-------+-------+ | Provider
| IPv6-only | Network
| Customer /
| Internet Connection /
| /
+------+--------+ \
| IPv6 | \
| Transition CE | \
| Router | |
+---+-------+---+ |
Network A | | Network B |
-+----------------+-+- -+---+-------------+- |
| | | | |
+---+------+ | +----+-----+ +-----+----+ |
| IPv6 | | | IPv4 | |IPv4/IPv6 | |
| Host | | | Host | | Host | |
+----------+ | +----------+ +----------+ | End-User
| | Network(s)
+------+--------+ |
| IPv6 | |
| Router | |
+------+--------+ |
Network C | |
-+-------------+--+- |
| | |
+---+------+ +----+-----+ |
| IPv6 | | IPv6 | /
| Host | | Host | /
+----------+ +----------+ /
Figure 2: Example of a Typical End-User Network
This architecture describes the:
o Basic capabilities of the IPv6 Transition CE Router
o Provisioning of the WAN interface connecting to the service
provider
o Provisioning of the LAN interfaces
The IPv6 Transition CE Router may be manually configured in an
arbitrary topology with a dynamic routing protocol or HNCP [RFC7788].
Automatic provisioning and configuration are described for a single
IPv6 Transition CE Router only.
Acknowledgements
Thanks to Mikael Abrahamsson, Fred Baker, Mohamed Boucadair, Brian
Carpenter, Lorenzo Colitti, Alejandro D'Egidio, Ian Farrer, Lee
Howard, Richard Patterson, Barbara Stark, Ole Troan, and James
Woodyatt for their review and comments in this and/or previous draft
versions of this document. Thanks also for the Last Call reviews by
Dan Romascanu (OPS-DIR); Christian Huitema (SEC-DIR); Daniele
Ceccarelli (RTG-DIR); Martin Stiemerling (TSV-ART); Matthew Miller
(Gen-ART); and Alissa Cooper, Benjamin Kaduk, Suresh Krishnan, Ben
Campbell, Spencer Dawkins, Mirja Kuhlewind, and Adam Roach (all
IESG).
Authors' Addresses Authors' Addresses
Jordi Palet Martinez Jordi Palet Martinez
The IPv6 Company The IPv6 Company
Molino de la Navata, 75 Molino de la Navata, 75
La Navata - Galapagar, Madrid 28420 La Navata - Galapagar, Madrid 28420
Spain Spain
Email: jordi.palet@theipv6company.com Email: jordi.palet@theipv6company.com
URI: http://www.theipv6company.com/ URI: http://www.theipv6company.com/
skipping to change at page 24, line 4 skipping to change at page 21, line 32
Authors' Addresses Authors' Addresses
Jordi Palet Martinez Jordi Palet Martinez
The IPv6 Company The IPv6 Company
Molino de la Navata, 75 Molino de la Navata, 75
La Navata - Galapagar, Madrid 28420 La Navata - Galapagar, Madrid 28420
Spain Spain
Email: jordi.palet@theipv6company.com Email: jordi.palet@theipv6company.com
URI: http://www.theipv6company.com/ URI: http://www.theipv6company.com/
Hans M.-H. Liu Hans M.-H. Liu
D-Link Systems, Inc. D-Link Systems, Inc.
17595 Mount Herrmann St. 17595 Mount Herrmann St.
Fountain Valley, California 92708 Fountain Valley, California 92708
US United States of America
Email: hans.liu@dlinkcorp.com Email: hans.liu@dlinkcorp.com
URI: http://www.dlink.com/ URI: https://www.dlink.com/
Masanobu Kawashima Masanobu Kawashima
NEC Platforms, Ltd. NEC Platforms, Ltd.
800, Shimomata 2-3, Kanda-Tsukasamachi
Kakegawa-shi, Shizuoka 436-8501 Chiyoda-ku, Tokyo 101-8532
Japan Japan
Email: kawashimam@vx.jp.nec.com Email: kawashimam@vx.jp.nec.com
URI: https://www.necplatforms.co.jp/en/ URI: https://www.necplatforms.co.jp/en/
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