Internet DRAFT - draft-ietf-v6ops-transition-ipv4aas
draft-ietf-v6ops-transition-ipv4aas
IPv6 Operations (v6ops) J. Palet Martinez
Internet-Draft The IPv6 Company
Intended status: Informational H. M.-H. Liu
Expires: August 1, 2019 D-Link Systems, Inc.
M. Kawashima
NEC Platforms, Ltd.
January 28, 2019
Requirements for IPv6 Customer Edge Routers to Support IPv4 Connectivity
as-a-Service
draft-ietf-v6ops-transition-ipv4aas-15
Abstract
This document specifies the IPv4 service continuity requirements for
an IPv6 Customer Edge (CE) router, either provided by the service
provider or by vendors who sell through the retail market.
Specifically, this document extends the "Basic Requirements for IPv6
Customer Edge Routers" (RFC7084) in order to allow the provisioning
of IPv6 transition services for the support of "IPv4 as-a-Service"
(IPv4aaS) by means of new transition mechanisms. The document only
covers transition technologies for delivering IPv4 in IPv6-only
access networks, commonly called "IPv4 as-a-Service" (IPv4aaS). This
is necessary because there aren't sufficient IPv4 addresses available
for every possible customer/device. However, devices or applications
in the customer LANs (Local Area Networks) may be IPv4-only or
IPv6-only and still need to communicate with IPv4-only services at
the Internet.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 1, 2019.
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Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. LAN-Side Configuration . . . . . . . . . . . . . . . . . 6
3.2. Transition Technologies Support for IPv4 Service
Continuity (IPv4 as-a-Service - IPv4aaS) . . . . . 6
3.2.1. 464XLAT . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . . 9
3.2.3. Lightweight 4over6 (lw4o6) . . . . . . . . . . . . . 10
3.2.4. MAP-E . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.5. MAP-T . . . . . . . . . . . . . . . . . . . . . . . . 11
4. IPv4 Multicast Support . . . . . . . . . . . . . . . . . . . 11
5. UPnP Support . . . . . . . . . . . . . . . . . . . . . . . . 12
6. Comparison to RFC7084 . . . . . . . . . . . . . . . . . . . . 12
7. Code Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
11. Annex A: Usage Scenarios . . . . . . . . . . . . . . . . . . 14
12. Annex B: End-User Network Architecture . . . . . . . . . . . 15
13. ANNEX C: Changes from -00 . . . . . . . . . . . . . . . . . . 18
14. ANNEX D: Changes from -01 . . . . . . . . . . . . . . . . . . 18
15. ANNEX E: Changes from -02 . . . . . . . . . . . . . . . . . . 18
16. ANNEX F: Changes from -03 . . . . . . . . . . . . . . . . . . 19
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
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23. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
23.1. Normative References . . . . . . . . . . . . . . . . . . 20
23.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
This document defines IPv4 service continuity features over an
IPv6-only network, for a residential or small-office router, referred
to as an "IPv6 Transition CE Router", in order to establish an
industry baseline for transition features to be implemented on such a
router.
These routers rely upon "Basic Requirements for IPv6 Customer Edge
Routers" [RFC7084]. The scope of this document is to ensure the IPv4
"service continuity" support, for devices in the LAN side. This
ensures that remote IPv4-only services continue to be accessible,
from an IPv6-only Internet Service Provider (ISP) access network from
both, IPv4-only and IPv6-only applications and devices in the LAN
side. These ISP access networks are typically referred to as Wide
Area Networks (WANs), even if in some cases they may be metropolitan
or regional. Figure 1 presents a simplified view of this
architecture.
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+------------+ +------------+ \
| IPv4-only | | IPv4/IPv6 | \
| Remote | | Remote | |
| Host | | Host | | Internet
+--------+---+ +---+--------+ |
| | /
| | /
+-+-----------+-+ \
| Service | \
| Provider | \
| Router | | Service
+-------+-------+ | Provider
| IPv6-only | Network
| Customer /
| Internet Connection /
| /
+------+--------+ \
| IPv6 | \
| Customer Edge | \
| Router | |
+---+-------+---+ |
LAN A | | LAN B | End-User
-+----------------+- -+-----+-------------+- | Network(s)
| | | |
+---+------+ +----+-----+ +-----+----+ |
| IPv6-only| | IPv4-only| |IPv4/IPv6 | /
| Host | | Host | | Host | /
+----------+ +----------+ +----------+ /
Figure 1: Simplified Typical IPv6-only Access Network
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
common situation when sufficient IPv4 addresses are no longer
available for every possible customer and device, causing IPv4
addresses to become prohibitively expensive. This, in turn, may
result in service providers provisioning IPv6-only WAN access. At
the same time, they need to ensure that both IPv4-only and IPv6-only
devices and applications in the customer networks can still reach
IPv4-only devices and applications in the Internet.
This document specifies the IPv4 service continuity mechanisms to be
supported by an IPv6 Transition CE Router, and relevant provisioning
or configuration information differences from [RFC7084].
This document is not a recommendation for service providers to use
any specific transition mechanism.
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Automatic provisioning of more complex topology than a single router
with multiple LAN interfaces may be handled by means of HNCP
[RFC7788] (Home Networking Control Protocol), which is out of the
scope of this document.
Since it is impossible to know prior to sale which transition
mechanism a device will need over its lifetime, an IPv6 Transition CE
Router intended for the retail market MUST support all the IPv4aaS
transition mechanisms listed in this document. Service providers who
specify feature sets for the IPv6 Transition CE Router, may define a
different set of features than those included in this document, for
example supporting only some of the transition mechanisms enumerated
in this document.
A complete description of "Usage Scenarios" and "End-User Network
Architecture" is provided in Annexes A and B, respectively, which
together with [RFC7084], will facilitate the reader to have a clearer
understanding of this document.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
This document uses the same terms as in [RFC7084], with minor
clarifications.
"IPv4aaS" stands for "IPv4 as-a-Service", meaning transition
technologies for delivering IPv4 in IPv6-only connectivity.
The term "IPv6 transition Customer Edge Router with IPv4aaS"
(shortened as "IPv6 Transition CE Router") is defined as an "IPv6
Customer Edge Router" that provides features for the delivery of IPv4
services over an IPv6-only WAN network, including IPv6-IPv4
communications.
The "WAN Interface" term used across this document, defines an IPv6
Transition CE Router attachment to an IPv6-only link used to provide
connectivity to a service provider network, including link Internet-
layer (or higher layers) "tunnels", such as IPv4-in-IPv6 tunnels.
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3. Requirements
The IPv6 Transition CE Router MUST comply with [RFC7084] (Basic
Requirements for IPv6 Customer Edge Routers) and this document adds
new requirements, as described in the following sub-sections.
3.1. LAN-Side Configuration
A new LAN requirement is added, which in fact is common in regular
IPv6 Transition CE Routers, and it is required by most of the
transition mechanisms:
L-1: The IPv6 Transition CE Router MUST implement a DNS proxy as
described in [RFC5625] (DNS Proxy Implementation Guidelines).
3.2. Transition Technologies Support for IPv4 Service Continuity (IPv4
as-a-Service - IPv4aaS)
The main target of this document is the support of IPv6-only WAN
access. To enable legacy IPv4 functionality, this document also
includes the support of IPv4-only devices and applications in the
customers LANs, as well as IPv4-only services on the Internet. Thus,
both IPv4-only and the IPv6-only devices in the customer-side LANs of
the IPv6 Transition CE Router are able to reach the IPv4-only
services.
Note that this document is only configuring the IPv4aaS in the IPv6
Transition CE Router itself, and not forwarding such information to
devices attached to the LANs, so the WAN configuration, availability
of native IPv4 or IPv4aaS, is transparent for them.
This document takes no position on simultaneous operation of one or
several transition mechanisms and/or native IPv4.
In order to seamlessly provide IPv4 service continuity in the
customer LANs, and allow automated IPv6 transition mechanism
provisioning, the following general transition requirements are
defined.
General transition requirements:
TRANS-1: The IPv6 Transition CE Router MUST support the DHCPv6 S46
priority options described in [RFC8026] (Unified IPv4-in-
IPv6 Softwire Customer Premises Equipment (CPE): A
DHCPv6-Based Prioritization Mechanism).
TRANS-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
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supported transition mechanisms.
TRANS-3: If an IPv6 Transition CE Router supports more than one LAN
subnet, the IPv6 Transition CE Router MUST allow
appropriate subnetting and configuration of the address
space among the several interfaces. In some transition
mechanisms, this may require differentiating mappings/
translations on a per-interface basis.
In order to allow the service provider to disable all the transition
mechanisms and/or choose the most convenient one, the IPv6 Transition
CE Router MUST follow the following configuration steps:
CONFIG-1: Request the relevant configuration options for each
supported transition mechanisms, which MUST remain
disabled at this step.
CONFIG-2: Following Section 1.4 of [RFC8026], MUST check for a valid
match in OPTION_S46_PRIORITY, which allows enabling/
disabling a transition mechanism.
CONFIG-3: Keep disabled all the transition mechanisms if no match is
found between the priority list and the candidate list,
unless a NAT64 prefix has been configured, in which case,
464XLAT MUST be enabled.
Because 464XLAT has not DHCPv6 configuration options, it can't be
included, at the time being, in the OPTION_S46_PRIORITY. In the
future, an update of [RFC8026] or a NAT64 DHCPv6 configuration
option, may enable it. Meanwhile, if an operator provides 464XLAT,
it needs to ensure that OPTION_S46_PRIORITY is not sent for any other
transition mechanism to the relevant customers.
The following sections describe the requirements for supporting each
one of the transition mechanisms. An IPv6 Transition CE Router
intended for the retail market MUST support all of them.
3.2.1. 464XLAT
464XLAT [RFC6877] is a technique to provide IPv4 service over an
IPv6-only access network without encapsulation. This architecture
assumes a NAT64 [RFC6146] (Stateful NAT64: Network Address and
Protocol Translation from IPv6 Clients to IPv4 Servers) function
deployed at the service provider or a third-party network.
The IPv6 Transition CE Router MUST support CLAT functionality
[RFC6877] if intended for the retail market. If 464XLAT is
supported, it MUST be implemented according to [RFC6877]. The
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following IPv6 Transition CE Router requirements also apply:
464XLAT requirements:
464XLAT-1: Unless a dedicated /64 prefix has been acquired, either
using DHCPv6-PD [RFC8415] (IPv6 Prefix Options for
DHCPv6) or by alternative means, the IPv6 Transition CE
Router MUST perform IPv4 Network Address Translation
(NAT) on IPv4 traffic translated using the CLAT.
464XLAT-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
[RFC6970] (UPnP Internet Gateway Device - Port Control
Protocol Interworking Function).
464XLAT-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE
Router MUST also implement [RFC7291] (DHCP Options for
the PCP). Following [RFC6887], if no PCP server is
configured, the IPv6 Transition CE Router MAY verify if
the default gateway, or the NAT64 is the PCP server. The
IPv6 Transition CE Router MUST use plain IPv6 mode (i.e.,
no IPv4-in-IPv6 encapsulation is used) to send PCP
requests to the server.
464XLAT-4: The IPv6 Transition CE Router MUST implement [RFC7050]
(Discovery of the IPv6 Prefix Used for IPv6 Address
Synthesis) in order to discover the PLAT-side translation
IPv4 and IPv6 prefix(es)/suffix(es).
464XLAT-5: If PCP is implemented, the IPv6 Transition CE Router MUST
follow [RFC7225] (Discovering NAT64 IPv6 Prefixes Using
the PCP), in order to learn the PLAT-side translation
IPv4 and IPv6 prefix(es)/suffix(es) used by an upstream
PCP-controlled NAT64 device.
464XLAT-6: The priority for the NAT64 prefix, in case the network
provides several choices, MUST be: 1) [RFC7225], 2)
[RFC7050].
The NAT64 prefix could be discovered by means of [RFC7050] only in
the case the service provider uses DNS64 [RFC6147]. It may be the
case that the service provider does not use or does not trust DNS64
[RFC6147] because the DNS configuration at the CE (or hosts behind
the CE) can be modified by the customer. In that case, the service
provider may opt to configure the NAT64 prefix by means of [RFC7225].
This can also be used if the service provider uses DNS64 [RFC6147].
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3.2.2. Dual-Stack Lite (DS-Lite)
Dual-Stack Lite [RFC6333] enables continued support for IPv4
services. Dual-Stack Lite enables a broadband service provider to
share IPv4 addresses among customers by combining two well-known
technologies: IP in IP (IPv4-in-IPv6) and Network Address Translation
(NAT). It is expected that DS-Lite traffic is forwarded over the
IPv6 Transition CE Router's native IPv6 WAN interface, and not
encapsulated in another tunnel.
The IPv6 Transition CE Router MUST implement DS-Lite B4 functionality
[RFC6333] if intended for the retail market. If DS-Lite is
supported, it MUST be implemented according to [RFC6333]. The
following IPv6 Transition CE Router requirements also apply:
DS-Lite requirements:
DSLITE-1: The IPv6 Transition CE Router MUST support configuration
of DS-Lite via the DS-Lite DHCPv6 option [RFC6334] (DHCPv6
Option for Dual-Stack Lite). The IPv6 Transition CE
Router MAY use other mechanisms to configure DS-Lite
parameters. Such mechanisms are outside the scope of this
document.
DSLITE-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF
[RFC6970] (UPnP Internet Gateway Device - Port Control
Protocol Interworking Function).
DSLITE-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE
Router SHOULD implement [RFC7291] (DHCP Options for the
PCP). If PCP [RFC6887] is implemented and a PCP server is
not configured, the IPv6 Transition CE Router MUST assume,
by default, that the AFTR is the PCP server. The IPv6
Transition CE Router MUST use plain IPv6 mode (i.e., no
IPv4-in-IPv6 encapsulation is used) to send PCP requests
to the server. The term "default" above is to be
interpreted as 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
Network Address Translation (NAT) on IPv4 traffic
encapsulated using DS-Lite [RFC6333].
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3.2.3. Lightweight 4over6 (lw4o6)
lw4o6 [RFC7596] specifies an extension to DS-Lite which moves the
NAPT function from the DS-Lite tunnel concentrator to the tunnel
client located in the IPv6 Transition CE Router, removing the
requirement for a CGN (Carrier Grade NAT, AFTR - Address Family
Transition Router) function in the tunnel concentrator and reducing
the amount of centralized state.
The IPv6 Transition CE Router MUST implement lwB4 functionality
[RFC7596] if intended for the retail market. If DS-Lite is
implemented, lw4o6 SHOULD be implemented as well. If lw4o6 is
supported, it MUST be implemented according to [RFC7596]. The
following IPv6 Transition CE Router requirements also apply:
lw4o6 requirements:
LW4O6-1: The IPv6 Transition CE Router MUST support configuration of
lw4o6 via the lw4o6 DHCPv6 options [RFC7598] (DHCPv6
Options for Configuration of Softwire Address and Port-
Mapped Clients). The IPv6 Transition CE Router MAY use
other mechanisms to configure lw4o6 parameters. Such
mechanisms are outside the scope of this document.
LW4O6-2: The IPv6 Transition CE Router MUST support the DHCPv4-over-
DHCPv6 (DHCP 4o6) transport described in [RFC7341] (DHCPv4-
over-DHCPv6 Transport).
LW4O6-3: The IPv6 Transition CE Router MAY support Dynamic
Allocation of Shared IPv4 Addresses as described in
[RFC7618] (Dynamic Allocation of Shared IPv4 Addresses).
3.2.4. MAP-E
MAP-E [RFC7597] is a mechanism for transporting IPv4 packets across
an IPv6 network using IP encapsulation, including an algorithmic
mechanism for mapping between IPv6 and IPv4 addresses.
The IPv6 Transition CE Router MUST support MAP-E CE functionality
[RFC7597] if intended for the retail market. If MAP-E is supported,
it MUST be implemented according to [RFC7597]. The following IPv6
Transition CE Router requirements also apply:
MAP-E requirements:
MAPE-1: The IPv6 Transition CE Router MUST support configuration of
MAP-E via the MAP-E DHCPv6 options [RFC7598] (DHCPv6 Options
for Configuration of Softwire Address and Port-Mapped
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Clients). The IPv6 Transition CE Router MAY use other
mechanisms to configure MAP-E parameters. Such mechanisms
are outside the scope of this document.
MAPE-2: The IPv6 Transition CE Router MAY support Dynamic Allocation
of Shared IPv4 Addresses as described in [RFC7618] (Dynamic
Allocation of Shared IPv4 Addresses).
3.2.5. MAP-T
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
the form of IPv6 domain transport.
The IPv6 Transition CE Router MUST support MAP-T CE functionality
[RFC7599] if intended for the retail market. If MAP-T is supported,
it MUST be implemented according to [RFC7599]. The following IPv6
Transition CE Router requirements also apply:
MAP-T requirements:
MAPT-1: The IPv6 Transition CE Router MUST support configuration of
MAP-T via the MAP-T DHCPv6 options [RFC7598] (DHCPv6 Options
for Configuration of Softwire Address and Port-Mapped
Clients). The IPv6 Transition CE Router MAY use other
mechanisms to configure MAP-T parameters. Such mechanisms
are outside the scope of this document.
MAPT-2: The IPv6 Transition CE Router MAY support Dynamic Allocation
of Shared IPv4 Addresses as described in [RFC7618] (Dynamic
Allocation of Shared IPv4 Addresses).
4. IPv4 Multicast Support
Existing IPv4 deployments support IPv4 multicast for services such as
IPTV. In the transition phase, it is expected that multicast
services will still be provided using IPv4 to the customer LANs.
If the IPv6 Transition CE Router supports delivery of IPv4 multicast
services, then it MUST support [RFC8114] (Delivery of IPv4 Multicast
Services to IPv4 Clients over an IPv6 Multicast Network) and
[RFC8115] (DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6
Prefixes).
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5. UPnP Support
If the UPnP WANIPConnection:2 service [UPnP-WANIPC] is enabled on a
CE router, but cannot be associated with an IPv4 interface
established by an IPv4aaS mechanism or cannot determine which ports
are available, an AddPortMapping() or AddAnyPortMapping() action MUST
be rejected with error code 729 "ConflictWithOtherMechanisms". Port
availability could be determined through PCP or access to a
configured port set (if the IPv4aaS mechanism limits the available
ports).
An AddPortMapping() request for a port that is not available MUST
result in "ConflictInMappingEntry".
An AddAnyPortMapping() request for a port that is not available
SHOULD result in a successful mapping with an alternative
"NewReservedPort" value from within the configured port set range, or
as assigned by PCP as per [RFC6970], Section 5.6.1.
Note that IGD:1 and its WANIPConnection:1 service have been
deprecated by OCF (Open Connectivity Foundation).
6. Comparison to RFC7084
This document doesn't include support for 6rd [RFC5969], because it
is an IPv6-in-IPv4 tunneling.
Regarding DS-LITE [RFC6333], this document includes slightly
different requirements, related to the support of PCP [RFC6887], IGD-
PCP IWF [RFC6970] and the prioritization of the transition
mechanisms, including dual-stack.
7. Code Considerations
At the time of this writing, one of the apparent main issues for
vendors to include new functionalities, such as support for new
transition mechanisms, is the lack of space in the flash (or
equivalent) memory. However, it has been confirmed from existing
open source implementations (OpenWRT/LEDE, Linux, VPP, others), that
adding the support for the new transition mechanisms, requires around
10-12 Kbytes, because most of the code base is shared among several
transition mechanisms, which are already supported by [RFC7084]. A
single data plane is common to all them, which typically means, in
popular CEs already in the market [OpenWRT], the new required code is
only about 0.15% of the total existing code size.
In general, the new requirements don't have extra cost in terms of
RAM memory, nor other hardware requirements such as more powerful
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CPUs, if compared to the cost of NAT44 code, so existing hardware
should be able to support all them with minimal impact.
The other issue seems to be the cost of developing the code for those
new functionalities. However, at the time of writing this document,
it has been confirmed that there are several open source versions of
the required code for supporting all the new transition mechanisms,
and several vendors already have implementations and provide it to
ISPs, so the development cost is negligible, and only integration and
testing cost may become an issue.
Finally, in some cases, operators supporting several transition
mechanisms may need to consider training costs for staff in all the
techniques for their operation and management, even if this is not
directly caused by supporting this document, but because the business
decisions behind that.
8. Security Considerations
The IPv6 Transition CE Router must comply with the Security
Considerations as stated in [RFC7084], as well as those stated by
each transition mechanism implemented by the IPv6 Transition CE
Router.
As described in [RFC8026] and [RFC8415] Security Consideration
sections, there are generic DHCP security issues, which in the case
of this document means that malicious nodes may alter the priority of
the transition mechanisms.
Access network architecture for securing DHCP within the access
network is out of scope of this document. Securing DHCP in the LAN
is also not in scope. DHCP packets MUST NOT be forwarded between LAN
and WAN interfaces of an IPv6 Transition CE router.
9. IANA Considerations
This document does not have any new specific IANA considerations.
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
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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.
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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
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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.
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+---------------+ \
| 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
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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.
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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.
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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
23.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",
BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009,
<https://www.rfc-editor.org/info/rfc5625>.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, DOI 10.17487/RFC5969, August 2010,
<https://www.rfc-editor.org/info/rfc5969>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <https://www.rfc-editor.org/info/rfc6146>.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
Beijnum, "DNS64: DNS Extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
DOI 10.17487/RFC6147, April 2011,
<https://www.rfc-editor.org/info/rfc6147>.
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[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
<https://www.rfc-editor.org/info/rfc6333>.
[RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
RFC 6334, DOI 10.17487/RFC6334, August 2011,
<https://www.rfc-editor.org/info/rfc6334>.
[RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation",
RFC 6877, DOI 10.17487/RFC6877, April 2013,
<https://www.rfc-editor.org/info/rfc6877>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013,
<https://www.rfc-editor.org/info/rfc6887>.
[RFC6970] Boucadair, M., Penno, R., and D. Wing, "Universal Plug and
Play (UPnP) Internet Gateway Device - Port Control
Protocol Interworking Function (IGD-PCP IWF)", RFC 6970,
DOI 10.17487/RFC6970, July 2013,
<https://www.rfc-editor.org/info/rfc6970>.
[RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
the IPv6 Prefix Used for IPv6 Address Synthesis",
RFC 7050, DOI 10.17487/RFC7050, November 2013,
<https://www.rfc-editor.org/info/rfc7050>.
[RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers", RFC 7084,
DOI 10.17487/RFC7084, November 2013,
<https://www.rfc-editor.org/info/rfc7084>.
[RFC7225] Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the
Port Control Protocol (PCP)", RFC 7225,
DOI 10.17487/RFC7225, May 2014,
<https://www.rfc-editor.org/info/rfc7225>.
[RFC7291] Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
the Port Control Protocol (PCP)", RFC 7291,
DOI 10.17487/RFC7291, July 2014,
<https://www.rfc-editor.org/info/rfc7291>.
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[RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I.
Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport",
RFC 7341, DOI 10.17487/RFC7341, August 2014,
<https://www.rfc-editor.org/info/rfc7341>.
[RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the Dual-
Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
July 2015, <https://www.rfc-editor.org/info/rfc7596>.
[RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S.,
Murakami, T., and T. Taylor, Ed., "Mapping of Address and
Port with Encapsulation (MAP-E)", RFC 7597,
DOI 10.17487/RFC7597, July 2015,
<https://www.rfc-editor.org/info/rfc7597>.
[RFC7598] Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec,
W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for
Configuration of Softwire Address and Port-Mapped
Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015,
<https://www.rfc-editor.org/info/rfc7598>.
[RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,
and T. Murakami, "Mapping of Address and Port using
Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July
2015, <https://www.rfc-editor.org/info/rfc7599>.
[RFC7618] Cui, Y., Sun, Q., Farrer, I., Lee, Y., Sun, Q., and M.
Boucadair, "Dynamic Allocation of Shared IPv4 Addresses",
RFC 7618, DOI 10.17487/RFC7618, August 2015,
<https://www.rfc-editor.org/info/rfc7618>.
[RFC8026] Boucadair, M. and I. Farrer, "Unified IPv4-in-IPv6
Softwire Customer Premises Equipment (CPE): A DHCPv6-Based
Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026,
November 2016, <https://www.rfc-editor.org/info/rfc8026>.
[RFC8114] Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., and Q.
Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
over an IPv6 Multicast Network", RFC 8114,
DOI 10.17487/RFC8114, March 2017,
<https://www.rfc-editor.org/info/rfc8114>.
[RFC8115] Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
Option for IPv4-Embedded Multicast and Unicast IPv6
Prefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017,
<https://www.rfc-editor.org/info/rfc8115>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
23.2. Informative References
[IPv6Survey]
Palet Martinez, J., "IPv6 Deployment Survey", January
2018,
<https://indico.uknof.org.uk/event/41/contribution/5/
material/slides/0.pdf>.
[OpenWRT] OpenWRT, "OpenWRT Packages", January 2018,
<https://openwrt.org/packages/start>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <https://www.rfc-editor.org/info/rfc7788>.
[UPnP-IGD]
UPnP Forum, "InternetGatewayDevice:2 Device Template
Version 1.01", December 2010,
<http://upnp.org/specs/gw/igd2/>.
[UPnP-WANIPC]
UPnP Forum, "WANIPConnection:2 Service", December 2010,
<http://upnp.org/specs/gw/
UPnP-gw-WANIPConnection-v2-Service.pdf>.
Authors' Addresses
Jordi Palet Martinez
The IPv6 Company
Molino de la Navata, 75
La Navata - Galapagar, Madrid 28420
Spain
Email: jordi.palet@theipv6company.com
URI: http://www.theipv6company.com/
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Hans M.-H. Liu
D-Link Systems, Inc.
17595 Mount Herrmann St.
Fountain Valley, California 92708
US
Email: hans.liu@dlinkcorp.com
URI: http://www.dlink.com/
Masanobu Kawashima
NEC Platforms, Ltd.
800, Shimomata
Kakegawa-shi, Shizuoka 436-8501
Japan
Email: kawashimam@vx.jp.nec.com
URI: https://www.necplatforms.co.jp/en/
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