2011 Fall Conference of Korea Information and Communications Society
The Recent Trends and Analysis on IPv4/IPv6 Transition Mechanism
Lee Jae Yong*, Bong Jin Sook*, Jee Hyun Wang, Yongtae Shin*
*Soongsil Univ., Yongsan International School of Seoul .
(*jylee, *jsbong)@cherry.ssu.ac.kr, [email protected], *[email protected])
Summary
A transition to IPv6, the next generation of internet address System,
from IPv4 is in the desperate need because IANA (Internet Assigned
Numbers Authority) has claimed to stop the global IPv4 address
allocation on February of 2011. There are many ongoing researches in
IETF (Internet Engineering Task Force) on the transition of IPv4 to
IPv6, as IPv6 will be applied in the near future. This paper briefly
discusses the transition mechanisms of IPv4 to IPv6, which is recently
being researched, and its concept and significant characteristics.
1. Introduction
An increase in network devices such as smart phones or IPTV, and in network services
such as cloud service or integrated wire and wireless services, has resulted in growing
demands of IP. This brought the depletion of preexisted IPv4 addresses and the need of
IPv6 to replace IPv4. There are many ongoing researches in IETF (Internet Engineering
Task Force) on the transition of IPv4 to IPv6, as IPv6 will be applied in the near future
[4].
This paper explains the transition mechanisms for IPv4 to IPv6 that are recently being
researched and analyzes their significant characteristics. Chapter 3 glances over the new
transition mechanisms; chapter 4 compares and analyzes the characteristics of these
transition mechanisms; chapter 5 presents the conclusion.
2. Related Research
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2011 Fall Conference of Korea Information and Communications Society
The classification of IPv4/IPv6 transition mechanisms is as written in Table 1.
<table1> Classification of IPv4/IPv6 Transition Mechanisms
Dual-Stack
N/A
*Configured Tunneling
Tunneling
*Automatic Tunneling
- 6to4, DSTM , ISATAP, Tunnel Broker, Teredo
* Network layer translation
- NAT-PT/SIIT, BIS
(Address) Translation
* Transport layer translation
- TRT, SOCKS Gateway
* Application layer translation
- BIA
The transition mechanisms are divided into Dual-Stack, Tunneling, and
(Address)Translation mechanisms.
Dual-Stack handles all IPv4 and IPv6 protocols in one system. Thus the one physical
system supporting Dual-Stack supports both IPv4 and IPv6.
A tunneling mechanism creates a tunnel at IPv4 network in order to communicate for
traffic moving from an IPv6 network to a nearby IPv4 network and ultimately to transit
to a desired IPv6 network.
Translation mechanisms interwork IPv4 and IPv6 network using an address converter.
Because it is not possible for one mechanism to be applied to all situations, each
mechanism should be appropriately utilized according to the given situation.
3. Recent IPv4/ IPv6 Transition Mechanisms
3.1 6rd (IPv6 rapid deployment)
6rd is a developed mechanism to modify and improve upon the problems of 6to4 for the
service provider to provide IPv6 service faster and easier in IPv4 site. 6rd communicates
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2011 Fall Conference of Korea Information and Communications Society
by using IPv6 prefix (ISPv6 prefix), which is allocated by each ISP in replace of 6to4’s
2002::/16, and by using anycast address, which is selected by ISP (Internet Service
Provider). 6rd can solve problems arose from 6to4’s open relay, since ISP supervises BR,
which acts as relay. Moreover, packets come from 6rd assure the validity to be head
towards an ISP site because 6rd uses prefix given to each ISP.
6rd’s configuration is as follows:
(figure 1) configuration of 6rd
6rd uses only CE router when communicating within the inner IPv4 network and forms
a tunnel between CE and BR when communicating with IPv6 network outside of BR.
3.2 CGN (Carrier-Grade NAT)
CGN is a combined transition mechanism that minimizes the network’s structural
change that occurs in IPv4 to IPv6 transition. CGN uses both Dual-Stack home gateway
and Dual-Stack CGN, which can both be reused during different transition periods.
Thus, in this transition period, CGN can be operated through the whole transition solely
with upgrades or reboots, without the need to change the device. The early stage of
transition uses CGN, which is later replaced by DS-Lite CGN.
CGN, having all the NAT’s functions and the automatic tunneling characteristics that
can be found in 6rd, aids for the recently facing shortage of IPv4 addresses and faster
applications of IPv6 [1].
CGN’s configuration is as follows:
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2011 Fall Conference of Korea Information and Communications Society
(figure 2) Configuration of CGN
CGN, a device that performs NAT functions, is used as the terminal of a tunnel for the
communication to IPv6
3.3 DS-Lite (Dual Stack Lite)
DS-Lite is a CGN basis solution that enables IPv4 communication to the end when the
service provider provides IPv6 network and can be used as a DS-Lite mode by
upgrading or resetting CGN devices.
DS-Lite has an advantage that can be applied in networks sharing IPv4 addresses by
providing IPv4-in-IPv6 and NAT functions [2].
DS-Lite’s configuration is as follows:
(figure 3) Configuration of DS-Lite
3.4 NAT64 (Network Address Translation64)
NAT64 is a translation mechanism that converts the information of IP header and ICMP
to an IPv4 or to an IPv6 version for the communication between IPv6 and IPv4
networks and can be viewed as an expanded mechanism of NAT-PT.
NAT64 is composed of a NAT64 router that converts an IPv6 header to an IPv4 header
by basing on IPv6 prefixes and IPv4 address domains and by using DNS64 server and
IP/ICMP conversion algorithm that provides IPv6 address [3].
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NAT64’s configuration is as follows:
(figure 4) Configuration of NAT 64
4. Comparison and Analysis of the Characteristics of Transition Mechanisms
Comparison and analysis of transition mechanisms are shown in <table 2>.
<table2> Feature of Transition Mechanisms
6rd
CGN
Mechanism
DS-Lite
NAT64
Tunneling
Tunneling
Tunneling
Translation
Section
CE – BR
HG – CGN
CPE – AFTR
-
Scalability
Very High
High
High
Middle
Use of NAT
-
O
O
O
NAT+Tunneling
Troubleshooting
Enhancement
(6rd)
of Double-NAT
of NAT-PT
Classification
Prefix
Notes
Configuration
by each ISP
Transition mechanisms are classified according to the roles, namely Tunneling and
Translation. A tunnel section explains where the Tunneling is used if using a Tunneling
mechanism. Analysis for Scalability is based on its applicability to diverse networks.
CGN and DS-Lite should be considered of the point of changing the equipments, and
NAT64 has the limitation only on to the beginning of the communication of IPv6
networks. Use of NAT notifies how well each mechanism can be applied to NAT
applied environment. Notes summarize the merits of each mechanism.
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5. Conclusion
In order for introducing IPv6 and transition into IPv6, the various projects, such as
establishing the foundation of the IPv6 Service Supporting System and of the IPv6
Supply and Promotion, and activating the researches and the test on IPv6 Network Base
Service are ongoing in Korea, by Korea Communication Committee and by Korea
Internet Security Agency.
This paper is compared and analyzed the compositions and the characteristics of newly
researched on transition mechanisms such as 6rd, CGN, DS-Lite, and NAT 64. Further
researches are needed to analyze the possible security problems and to develop the plan
to enhance the security to minimize the problems when applying on IPv4/ IPv6
transition mechanisms.
References
[1] S. Jiang, D. GUO, B. Carpenter, An Incremental Carrier -Grade NAT
(CGN) for IPv6 Transition, RFC 6264, 2011. 06.
[2] A. Durand, R. Droms, J. Woodyatt, T. Lee, Dual -Stack Lite Broadband
Deployments Following IPv4 Exhaustion, RFC 6333, 2011. 08.
[3] M. Bagnulo, P. Matthews, I. van Beijnum, Stateful NAT64: Network
Address and Protocol Translation from IPv6 Clients to IPv4 Servers Draftietf-behave-v6v4-xlate-stateful-12, RFC 6146, 2011. 01.
[4] J. Arkko, F. Baker, IPv6 Transition Guidelines, RFC 6180, 2011. 05.
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