Internet Engineering Task Force G. Chen
Internet-Draft H. Deng
Intended status: Informational China Mobile
Expires: April 21, 2011 October 18, 2010
NAT64-CPE Mode Operation for Opening Residential Service
draft-chen-v6ops-nat64-cpe-00
Abstract
The document has proposed an approach of NAT64-CPE mode, which would
give residential service opportunities to be accessed by remote
subscribers going through IPv6 networks. The document captures the
fundamental NAT64 functionalities with special cares to fit into CPE
scenarios and don't need cooperate with DNS64 any more. It will
compatible with legacy residential servers and no further updates
requirements to DNS.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. NAT64-CPE Mode Scenario Overviews . . . . . . . . . . . . . . . 3
3. NAT64-CPE Mode Operation . . . . . . . . . . . . . . . . . . . 4
3.1. CPE Functionalites Description . . . . . . . . . . . . . . 4
3.2. DNS Configuration Consideration . . . . . . . . . . . . . . 5
3.3. NAT64-CPE Mode Operation Example . . . . . . . . . . . . . 5
4. NAT64-CPE Approach Discussion . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Informative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The document is aimed at proposing an approach of NAT64-CPE mode,
which would give residential service opportunities to be accessed by
remote subscribers going through IPv6 networks. The document
captures the fundamental NAT64[NAT64] functionalities with special
cares to fit into CPE scenarios. In these scenarios, the NAT64-CPE
don't need cooperate with DNS64[DNS64] any more, whereby this
mechanism allows an IPv6-only client (i.e. either a host with only
IPv6 stack, or a host with both IPv4 and IPv6 stack, but only with
IPv6 connectivity or a host running an IPv6 only application) to
initiate communications to an IPv4-only residential service server.
Recently,IPv6 transition is fairly prevalent due to the depletion of
IPv4 soon enough. However, the large number of installed CPE is
IPv4-only based and likely to remain for several years. Considering
the existing deployment approaches, majority of ISP assigned private
IPv4 address to their customers, including residential servers. The
nature of private IPv4 would block the end-to-end bi-directional
communications. On the other hand, the goal of Internet services is
to offer users ubiquitous experiences. User will be certainly
supposed to able to enjoy such conveniences regardless of where we
are. Therefore, ISP would take advantage of the accessibilities of
residential services to provide plenty of services. Fortunately,
IPv6 will get ISP end-to-end benefits. During IPv6 migration period,
NAT64-CPE mode could overcome the obstacles to achieve final goals.
The document is structured as follows. Section 2 describes
appropriate scenario the NAT64-CPE mode fit to. Section 3 enumerates
various functional parts for NAT64-CPE operation. Section 4 focus on
the benefits the NAT64-CPE could bring. Section 5 is further
securities consideration.
2. NAT64-CPE Mode Scenario Overviews
Figure 1 illustrates a possible network scenario where an IPv6-only
client attached to a dual-stack network, but the destination server
is running on a private site where there is NAT64-CPE numbered with
public IPv6 addresses and private IPv4 addresses. DNS is located in
dual stack Internet for naming-resolving.
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+----------------------+ +------------------------------+
| Dual Stack Internet | | IPv4 Private site (Net 10) |
| | | |
| | | |
| | | +----------+ |
| +----+ +---------+ | | |
| | H1 |-----------|NAT64-CPE|-------------| Server | |
| +----+ +---------+ | | |
| v6 only / | | +----------+ |
| Host / | | IPv4-only |
| +-----+ | | etc. 10.1.1.1 |
| | DNS | | | |
| +-----+ | | |
+----------------------+ +------------------------------+
Figure 1: NAT64-CPE Network Scenario
This scenario appears in ISP network quite popular. As the
instances, visitors go through distant network to take care of family
affairs, like monitoring house security via residential camera,
manipulating household appliances remotely prior to comeback home.
3. NAT64-CPE Mode Operation
The whole process of NAT64-CPE operation involves CPE, DNS and
addressing mechanism. This section illustrates different parts of
functionalities.
3.1. CPE Functionalities Description
Two kinds of functions the NAT64-CPE would take on. First, it will
perform the functionalities that normal CPE does except NAT44
forwarding, like assigning private IPv4 address to their attached
residential servers. Additionally, CPE will allocate private IPv4
address to the servers depending on the server MAC address.
Therefore, the server could always get constant private IPv4 address.
Second, CPE should carry NAT64 capable mode without integrating
DNS64. According to normative handing, NAT64-CPE translates in-
coming IPv6 destination address by striping NAT64 IPv6-prefix and
maintains a IPv4 pool for translating IPv6 sources address. Therein,
the NAT64 IPv6 prefix will be NSP specified in IPv6 Addressing of
IPv4/IPv6 Translators [IPv6 Addressing of IPv4/IPv6 Translators].
And, ISP will reserve distinct NSP for each CPE.
The prerequisite here is that NAT64-CPE should maintain address
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mapping between inner IP address and outer IP address. PCP [PCP]
could handle such problems. But that goes beyond the scope of this
draft. Also, NAT64-CPE would install ALG, but it is optional.
3.2. DNS Configuration Consideration
Each residential services should be represented by FQDN format so as
to users could easily remember and understand. The corresponding
naming resource record should be stored as AAAA. The record's IPv6
address is synthesized by NAT64 prefix and private IPv4 address. The
IPv6 format is compliant with assembling IPv6 address in DNS64.
The deployed DNS just follow regular DNS handling. There is no
demands for performing DNS64 process.
3.3. NAT64-CPE Mode Operation Example
Figure 2 demonstrates the NAT64-CPE Mode operation flow, in which IPv6
host initiate service interaction with residential server remotely.
The detailed actions that different entities performed was described
afterwards.
IPv6-only
Host DNS NAT64-CPE Server
| | |IPv4 assigning |
(1) | | |<- - - - - - - >|
|AAAA query: | | |
|household.cam| | |
(2) |============>| | |
|AAAA response| | |
|2001::a01:101| | |
(3) |<============| | |
| IPv6 traffic | |
(4) |------------------------->| |
| | +-----------+ IPv4 |
(5) | | | NAT64-CPE |--------->|
| IPv6 traffic |translation| IPv4 |
(6) |<-------------------| |<---------|
| | +-----------+ |
Figure 2: NAT64-CPE Mode Operation Example
(1) NAT64-CPE should be configured with NAT64 prefix, which is
allocated by ISP. In that case, the NAT64 prefix is 2001::/64.
NAT64-CPE assign private IPv4 address to the servers depending on the
server MAC address. And, NAT64-CPE already has maintained the
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mapping between inner IP address and outer IP address.
(2)IPv6-only host initiates AAAA query for resolving service name,
for example, that is household.cam.
(3)DNS response AAAA record to the previous query. The IPv6 address
of this service is synthesized by NAT64 prefix and assigned private
IPv4 address. That is 2001::a01:101
(4)IPv6-only host send IPv6 traffic targeting to 2001::a01:101. The
IPv6 traffic is routed to CPE.
(5)NAT64-CPE detects incoming IPv6 packets and algorithmically
translated to IPv4 addresses by using the algorithm defined in
[I-D.ietf-behave-address-format]. The translated IPv4 traffic is
headed to IPv4-only residential server and perform somehow process.
(6)The residential IPv4 server responses these requests by IPv4
traffic, which will be sent to CPE. CPE performs reversed algorithm
to translate IPv4 to IPv6 based on the maintained mapping
information. And then, CPE generate IPv6 traffic and transmit to
IPv6-only Host.
4. NAT64-CPE Approach Discussion
Considering above description, NAT64-CPE has following specific
features.
o NAT64-CPE is capable of making residential server to be accessed,
by means of which users could visit the IPv4-only server remotely.
o NAT64-CPE is a solely NAT64 deployed solution in CPE environment.
It will compatible with legacy residential servers and no further
updates requirements to DNS. Therefore, it's liable to be
deployed.
5. Security Considerations
Essentially, there are strong demands to have thorough security
mechanism to prevent privacy invasion in CPE scenario. The detailed
considerations need to be further identified.
6. IANA Considerations
This memo includes no request to IANA.
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7. Informative References
[DNS64] Bagnulo, M., "DNS64: DNS extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", IETF
Internet-draft draft-ietf-behave-dns64-10.txt, July 2010.
[IPv6 Addressing of IPv4/IPv6 Translators]
Bao, C., "IPv6 Addressing of IPv4/IPv6 Translators",
draft-ietf-behave-address-format-10.txt (work in
progress), August 2010.
[NAT64] Bagnulo, M., "Stateful NAT64: Network Address and Protocol
Translation from IPv6 Clients to IPv4 Servers",
draft-ietf-behave-v6v4-xlate-stateful-12.txt (work in
progress), July 2010.
[PCP] Wing, D., "Pinhole Control Protocol (PCP)",
draft-wing-softwire-port-control-protocol-02.txt (work in
progress), July 2010.
Authors' Addresses
Gang Chen
China Mobile
53A,Xibianmennei Ave.,
Xuanwu District,
Beijing 100053
China
Email: phdgang@gmail.com
Hui Deng
China Mobile
53A,Xibianmennei Ave.
Beijing 100053
P.R.China
Phone: +86-13910750201
Email: denghui02@gmail.com
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