Internet Engineering Task Force M. Mawatari
Internet-Draft Japan Internet Exchange Co.,Ltd.
Intended status: Informational M. Kawashima
Expires: April 26, 2012 NEC AccessTechnica, Ltd.
October 24, 2011
464XLAT: Combination of Stateful and Stateless Translation
draft-mawatari-softwire-464xlat-01
Abstract
This document describes a method (464XLAT) for IPv4 connectivity
across IPv6 network by combination of stateful translation and
stateless translation. 464XLAT is a simple technique to provide IPv4
access service while avoiding encapsulation just by using twice IPv4/
IPv6 translation standardized in [RFC6145] and [RFC6146].
Status of this Memo
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This Internet-Draft will expire on April 26, 2012.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Network Architecture . . . . . . . . . . . . . . . . . . . . . 4
5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Implementation Considerations . . . . . . . . . . . . . . . . . 4
6.1. IPv6 Address Format . . . . . . . . . . . . . . . . . . . . 4
6.2. DNS Proxy Implementation . . . . . . . . . . . . . . . . . 5
6.3. IPv6 Fragment Header Consideration . . . . . . . . . . . . 5
6.4. Auto Prefix Assignment . . . . . . . . . . . . . . . . . . 5
7. Deployment Considerations . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The IANA unallocated IPv4 address pool was exhasuted on February 3,
2011. It is likely that each RIR's unallocated IPv4 addres pool will
exhaust in the near future. In this situation, it will be difficult
for most ISPs to assign global IPv4 address to end users.
This document describes an IPv4 over IPv6 solution as one of the
measures of IPv4 address exhaustion and encouragement of IPv6
deployment.
This method (464XLAT) in this document is using twice IPv4/IPv6
translation standardized in [RFC6145] and [RFC6146]. It does not
need DNS64 [RFC6147] technology for the purpose of providing IPv4
over IPv6 service by this method. It is also possible to provide
single IPv4/IPv6 translation service, which will be needed in the
near future. This feature is one of the advantages, because it can
be an encouragement to gradually transition to IPv6.
This method is a combination of existing technologies and provides a
simple way of providing connectivity to the IPv4 Internet without the
use of a CGN nor a port mapping algorithm.
2. 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 [RFC2119].
3. Terminology
PLAT: PLAT is Provider side translator(XLAT). A stateful
translator complies with [RFC6146] that performs 1:N
translation. It translates global IPv6 address to global
IPv4 address, and vice versa.
CLAT: CLAT is Customer side translator(XLAT). A stateless
translator complies with [RFC6145] that performs 1:1
translation. It algorithmically translates private IPv4
address to global IPv6 address, and vice versa. It has also
IPv6 router function that can forward IPv6 packet for IPv6
hosts in end-user network. Furthermore, it has DNS Proxy
function with IPv6 transport that provides name resolution
for IPv4 hosts and IPv6 hosts in end-user network. The
presence of DNS64 [RFC6147] and any port mapping algorithm
are not required.
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4. Network Architecture
464XLAT method is shown in the following figure.
----
| v6 |
----
|
---- | .---+---. .------.
| v6 |-----+ / \ / \
---- | ------ / IPv6 \ ------ / IPv4 \
+---| CLAT |---+ Internet +---| PLAT |---+ Internet |
------- | ------ \ / ------ \ /
|v4p/v6 |--+ `---------' `----+----'
------- | |
----- | -----
| v4p |----+ | v4g |
----- | -----
<- v4p -> XLAT <--------- v6 ---------> XLAT <- v4g ->
v6 : Global IPv6
v4p : Private IPv4
v4g : Global IPv4
Figure 1: Network Topology
5. Applicability
When ISP has IPv6 access network infrastructure and 464XLAT, ISP can
provide IPv4 service to end users.
If the IXP or another provider operates the PLAT, all ISPs have to do
is to deploy IPv6 access network. All ISPs do not need IPv4
facilities. They can migrate quickly their operation to an IPv6-only
environment. Incidentally, Japan Internet Exchange(JPIX) is
providing 464XLAT trial service since July 2010.
6. Implementation Considerations
6.1. IPv6 Address Format
IPv6 address format in 464XLAT is presented in the following format.
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+-----------------------------------------------+---------------+
| XLAT prefix(96) | IPv4(32) |
+-----------------------------------------------+---------------+
IPv6 Address Format for 464XLAT
Source address and destination address have IPv4 address embedded in
the low-order 32 bits of the IPv6 address. The format is defined in
Section 2.2 of [RFC6052]. However, 464XLAT does not use the Well-
Known Prefix "64:ff9b::/96".
6.2. DNS Proxy Implementation
CLAT perform DNS Proxy for IPv4 hosts and IPv6 hosts in end-user
network. It MUST provide name resolution with IPv6 transport. It
does not need DNS64 [RFC6147] function.
6.3. IPv6 Fragment Header Consideration
In the 464XLAT environment, the PLAT and CLAT SHOULD include an IPv6
Fragment Header, since IPv4 host does not set the DF bit. However,
the IPv6 Fragment Header has been shown to cause operational
difficulties in practice due to limited firewall fragmentation
support, etc. Therefore, the PLAT and CLAT may provide a
configuration function that allows the PLAT and CLAT not to include
the Fragment Header for the non-fragmented IPv6 packets. At any
rate, both behaviors SHOULD match.
6.4. Auto Prefix Assignment
Source IPv6 prefix assignment in CLAT is via DHCPv6 prefix delegation
or another method. Destination IPv6 prefix assignment in CLAT is via
some method. (e.g., DHCPv6 option, TR-069, DNS, HTTP, etc.)
7. Deployment Considerations
Even if the Internet access provider for consumers is different from
the PLAT provider (another Internet access provider or Internet
exchange provider, etc.), it can implement traffic engineering
independently from the PLAT provider. Detailed reasons are below.
1. The Internet access provider for consumers can figure out IPv4
source address and IPv4 destination address from translated IPv6
packet header, so it can implement traffic engineering based on
IPv4 source address and IPv4 destination address (e.g. traffic
monitoring for each IPv4 destination address, packet filtering
for each IPv4 destination address, etc.). The Tunneling methods
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do not have such a advantage, without any deep packet inspection
for visualizing the inner IPv4 packet of the tunnel packet.
2. If the Internet access provider for consumers can assign IPv6
prefix greater than /64 for each subscriber, this 464XLAT method
can separate IPv6 prefix for native IPv6 packets and XLAT prefix
for IPv4/IPv6 translation packets. Accordingly, it can identify
the type of packets ("native IPv6 packets" and "IPv4/IPv6
translation packets"), and implement traffic engineering based on
IPv6 prefix.
And this 464XLAT method have two capabilities. One is a IPv6 -> IPv4
-> IPv6 translation for sharing global IPv4 addresses, another is a
IPv4 -> IPv6 translation for reaching IPv6 only servers from IPv4
only clients that can not support IPv6. IPv4 only clients will
remain for a while.
8. Security Considerations
To implement a PLAT, see security considerations presented in Section
5 of [RFC6146].
To implement a CLAT, see security considerations presented in Section
7 of [RFC6145]. And furthermore, the CLAT SHOULD perform Bogon
filter, and SHOULD have IPv6 firewall function as a IPv6 router. It
is useful function for native IPv6 packet and translated IPv6 packet.
The CLAT SHOULD check IPv6 packet received from WAN interface. If
the packet is invalid prefix (i.e., it is not XLAT prefix), then
SHOULD silently drop the packet. In addition, the CLAT SHOULD check
IPv4 packet after the translation. If the packet is not match
private IPv4 address of LAN, then SHOULD silently drop the packet.
9. IANA Considerations
This document has no actions for IANA.
10. Acknowledgements
The authors would like to thank JPIX NOC members and Seiichi Kawamura
for their helpful comments.
11. References
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11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
October 2010.
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation", RFC 6144, April 2011.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
11.2. Informative References
[I-D.murakami-softwire-4v6-translation]
Murakami, T., Chen, G., Deng, H., Dec, W., and S.
Matsushima, "4via6 Stateless Translation",
draft-murakami-softwire-4v6-translation-00 (work in
progress), July 2011.
[I-D.xli-behave-divi]
Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual-
Stateless IPv4/IPv6 Translation", draft-xli-behave-divi-03
(work in progress), July 2011.
[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,
April 2011.
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Authors' Addresses
Masataka Mawatari
Japan Internet Exchange Co.,Ltd.
KDDI Otemachi Building 19F, 1-8-1 Otemachi,
Chiyoda-ku, Tokyo 100-0004
JAPAN
Phone: +81 3 3243 9579
Email: mawatari@jpix.ad.jp
Masanobu Kawashima
NEC AccessTechnica, Ltd.
800, Shimomata
Kakegawa-shi, Shizuoka 436-8501
JAPAN
Phone: +81 537 23 9655
Email: kawashimam@vx.jp.nec.com
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