Internet DRAFT - draft-matsuhira-oht
draft-matsuhira-oht
Network Working Group N. Matsuhira
Internet-Draft Neptela
Intended status: Informational 26 February 2024
Expires: 29 August 2024
Outer Header Translator
draft-matsuhira-oht-01
Abstract
Network address translation technology has a convenient aspect,
however, it has the side effect of breaking end-to-end transparency.
This document proposes a technology that achieves both network
address translation and end-to-end transparency. This technology may
provide solutions for mobility, migration, multihoming, policy
routing, etc.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 29 August 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Concept of Architecture . . . . . . . . . . . . . . . . . . . 3
3. Terminoligy . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Network Configuration . . . . . . . . . . . . . . . . . . . . 4
5. OHT Processing . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Support IP protocol versions . . . . . . . . . . . . . . 5
5.2. Encapsulation / Decapsulation . . . . . . . . . . . . . . 5
5.3. OHT Table . . . . . . . . . . . . . . . . . . . . . . . . 5
5.4. Address Type . . . . . . . . . . . . . . . . . . . . . . 6
6. Possible Solutions . . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
NAT [RFC1631] was devised as a short-term solution to the exhaustion
of IPv4 addresses, and is placed at the boundary between a private
network (Intranet) built using private addresses [RFC1597] and the
Internet. Communication closed to the intranet is made possible by
using private addresses. A global address is required only for hosts
communicating with the Internet, and this is achieved by NAT
performing address translation.This technology supported the
expansion of the Intranets and the Internet.
After that, technology was developed that allows multiple hosts to
share a single global IPv4 address. This technology is called NAPT
(Network Address Port Translation). This technology was primarily
used in SOHO (small office/home office) networks and supported the
expansion of SOHO networks and the Internet.
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On the other hand, 8+8/GSE [I-D.ietf-ipngwg-gseaddr] was proposed in
the early stages of the IPv6 discussion. This proposal involves
translating the prefix part of the IPv6 address. Therefore, it has
the side effects of NAT. As a result, there was a lot of discussion.
Note that this has nothing to do with IPv4 address exhaustion.
Furthermore, as for the transition technology from IPv4 to IPv6,
technologies that involve address translation such as NAT-PT
[RFC2766] were considered, but this is also a technology similar to
NAT and has a lot of discussion.
Internet Transparency is summarized in RFC2775 [RFC2775].
2. Concept of Architecture
End-to-end transparency can be maintained by encapsulating packets
generated by the host and subjecting only the encapsulated outer IP
header to address translation. That is, internal packets must not be
translation.
Figure 1 shows encapsulation. IP Encapsulation within IP is
described in RFC2003 [RFC2003].
+-------------------------+
| |
| Outer IP Header |
| |
+-------------------------+ +-------------------------+
| | | |
| IP Header | | IP Header |
| | | |
+-------------------------+ ====> +-------------------------+
| | | |
| | | |
| IP Payload | | IP Payload |
| | | |
| | | |
+-------------------------+ +-------------------------+
Figure 1
Typically, the destination IP address in the outer header is the
address of the tunnel endpoint. However, in this concept, the outer
header is a copy of the inner header. If the outer header is not
translated, the outer header remains the same as the internal header.
After encapsulation, the outer header of the packet is subject to
translate.
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3. Terminoligy
This section defines terminologies.
Outer Header Translator
Refers to the device or processing module that performs this
processing.
Outer Header Translation
Show the method.
Outer Header Translation Table
Outer Header Translation Table
Outer Header Translation Relay
Indicates communication via one or more Outer Header Translators
Outer Header Translation Domain
Indicates a domain using OHT.
4. Network Configuration
This section describes network configuration with OHT.
Figure 2 shows sample network configuration with OHT.
~~~~~~~~~~ ~~~~~~~~~
+-------+ / IP / +-------+ / IP / +-------+
| OHT |----/ Network /----| OHT |----/ Network /----| OHT |
+----+--+ / / +-------+ / / +--+----+
| ~~~~~~~~~~~ ~~~~~~~~~~ |
---+-+---- ----+-+---
| |
+--+---* +---+--*
| HOST | | HOST |
+------* +------*
Figure 2
Typically, OHT is implemented in a router. Encapsulation and
decoupling are also implemented in routers. However, other
implementations are possible. For example, encapsulation and
decapsulation may be implemented in the host.
5. OHT Processing
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5.1. Support IP protocol versions
Figure 3 shows possible IP protocol versions, i.e. IPv4 [RFC791] and
IPv6 [RFC8200]combinations.
+---------------------------+----------------------------+
| Outer IP Header Version | Inner IP Protocol Version |
+---------------------------+----------------------------+
| | IPv6 |
| IPv6 +----------------------------+
| | IPv4 |
+---------------------------+----------------------------+
| | IPv6 |
| IPv4 +----------------------------+
| | IPv4 |
+---------------------------+----------------------------+
Figure 3
There are four combinations, and dealing with all of them would be
complicated. Therefore, it would be good if the Outer IP Header
could be limited to IPv6 only.
5.2. Encapsulation / Decapsulation
In this concept, the outer header is a copy of the inner header.
In this concept, the outer header is essentially a copy of the inner
header. According to this, the possible combinations of IP protocol
versions are IPv6 over IPv6 and IPv4 over IPv4. If it is assumed
that it will be applied to an IPv6 only backbone, accommodation of
IPv4 will be possible with IPv6 over IPv6 over IPv4. In this case,
the IPv6 Addresses with Embedded IPv4 Addresses can be used as the
IPv6 address in the internal IPv6 header.
If support for IPv4 private addresses, M46A [I-D.matsuhira-m46a]
might be useful.
5.3. OHT Table
Figure 4 shows the structure of OHT table.
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+------+------+------+------+------+------+------+------++------+------+
| Inner| Inner| Inner| Inner| Inner| Inner| Inner| Outer|| Next | Next |
| Src | Src | dst | dst | Next | src | dst | Src || Outer| Outer|
| IP | IP | IP | IP | Hdr | port | port | IP || Src | Dst |
| addr | mask | addr | mask | | | | addr || IP | IP |
| | | | | | | | || addr | addr |
+------+------+------+------+------+------+------+------++------+------+
| | | | | | | | || | |
+------+------+------+------+------+------+------+------++------+------+
| | | | | | | | || | |
+------+------+------+------+------+------+------+------++------+------+
| : | : | : | : | : | : | : | : || : | : |
| : | : | : | : | : | : | : | : || : | : |
+------+------+------+------+------+------+------+------++------+------+
Figure 4
The table may contain Traffic Class and Flow Label.
5.4. Address Type
Figure 5 shows possible address type [RFC4291] combinations for outer
header destination addresses and inner header destination addresses
are shown.
+------------------------------------------------------------+
| outer header +---------+---------+-----------+
| | unicast | anycast | multicast |
| | address | address | Address |
| | Global | | |
+-+-----------+--------------+---------+---------+-----------+
|i| unicast | Global | o | o | ? |
|n| address +--------------+---------+---------+-----------+
|n| | Embedded IPv4| o | o | ? |
|e| +--------------+---------+---------+-----------+
|r| | Link-Local | x | x | x |
| | +--------------+---------+---------+-----------+
|h| | Unique Local | o | o | ? |
|d+-----------+--------------+---------+---------+-----------+
|r| anycast address | o | o | ? |
| +--------------------------+---------+---------+-----------+
| | multicast address | o | o | o |
+-+--------------------------+---------+---------+-----------+
Figure 5
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6. Possible Solutions
OHT provides solutions for mobility, migration, multi-homing, policy
routing, service function chaining, etc. More details will be
provided in the future versions.
7. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
8. Security Considerations
IPsec for internal packets works because internal packets are
forwarded unchanged.
9. Acknowledgements
It may be listed in the future.
10. References
10.1. Normative References
[I-D.matsuhira-m46a]
Matsuhira, N., "Multiple IPv4 - IPv6 mapped IPv6 address
(M46A)", Work in Progress, Internet-Draft, draft-
matsuhira-m46a-15, 3 October 2023,
<https://datatracker.ietf.org/doc/html/draft-matsuhira-
m46a-15>.
[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
DOI 10.17487/RFC2003, October 1996,
<https://www.rfc-editor.org/info/rfc2003>.
[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>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
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[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
10.2. Informative References
[I-D.ietf-ipngwg-gseaddr]
O'Dell, M. D., "GSE - An Alternate Addressing Architecture
for IPv6", Work in Progress, Internet-Draft, draft-ietf-
ipngwg-gseaddr-00, 24 February 1997,
<https://datatracker.ietf.org/doc/html/draft-ietf-ipngwg-
gseaddr-00>.
[RFC1597] Rekhter, Y., Moskowitz, B., Karrenberg, D., and G. de
Groot, "Address Allocation for Private Internets",
RFC 1597, DOI 10.17487/RFC1597, March 1994,
<https://www.rfc-editor.org/info/rfc1597>.
[RFC1631] Egevang, K. and P. Francis, "The IP Network Address
Translator (NAT)", RFC 1631, DOI 10.17487/RFC1631, May
1994, <https://www.rfc-editor.org/info/rfc1631>.
[RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address
Translation - Protocol Translation (NAT-PT)", RFC 2766,
DOI 10.17487/RFC2766, February 2000,
<https://www.rfc-editor.org/info/rfc2766>.
[RFC2775] Carpenter, B., "Internet Transparency", RFC 2775,
DOI 10.17487/RFC2775, February 2000,
<https://www.rfc-editor.org/info/rfc2775>.
Author's Address
Naoki Matsuhira
Neptela
Japan
Email: matsuhira.ietf@gmail.com
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