Best Transition Method for Large Enterprise Networks
Degree Programme in Business
Information Technology
Spring 2012
Nguyen, Phu Minh Nguyen
Nguyen, Quynh Anh
Lahti University of Applied Sciences
Degree Programme in Business Information Technology
Transition from Ipv4 to Ipv6
Best Method for Large Enterprise
Bachelor’s Thesis of Degree Programme in Business Information Technology, 97
pages, 25 pages of appendices
Spring 2012
On 8 June, 2011, over 1000 top websites in the world took part in an event called
“World IPv6 Day”. As IPv4 are running out, the need for changing to IP next
generation, IPv6 is obvious. This study aims at finding the best method of
transition from IPv4 to IPv6 for large enterprise networks.
This study analyzed experiences of several large enterprises that had deployed
IPv6. Key factors on the success and failure of IPv6 deployment were synthesized
from findings from those enterprises.
This research utilizes qualitative approach and inductive reasoning along with
design science approach. Seven guidelines of design science method are followed
strictly for better end results. Open-ended interviews will be data collection
methods of the study. Documents, such as articles, books, and websites also
provide lots of information. Content analysis helps the authors to look directly
into context of documents to find the core meaning. The content of this study was
examined on two scales: technical side and managerial side.
Findings upon data collected reveal several significant factors which affect IPv6
implementation project. Hence, a solution, the most applicable transition method
was concluded. This method was then tested on a virtual environment simulating
a large network model. It was proven to be working.
Keywords: internet protocol, IP, IPv4, transition, transition method, IPv6, large
enterprise, network, IPv6 readiness
This thesis is dedicated to my beloved family, Nguyễn Phú Thọ, Nguyễn Thị
Tùng, and Nguyễn Phú Quỳnh Như, who gave birth to me at the first place,
raised me up and always give me care and love to the fullest. I would not be
where I am now without their endless love, huge encouragement and
unconditional support. Last but not least, I would like to thank my girlfriend, Đỗ
Thị Minh Châu, for her loving care and wholehearted support, as well as
patience while I am doing my thesis.
Nguyen Phu Minh Nguyen
To my beloved parents, family and friends, who are always beside me.
Nguyen Quynh Anh
We would like to express our appreciation to all those who gave us the possibility
to complete this Bachelors degree thesis. First and foremost we are deeply
indebted to our supervisor, Professor Torsti Rantapuska, who has supported us
throughout our thesis with his patience and knowledge whilst allowing us the
room to work in our own way. Furthermore, we would like to offer our sincerest
gratitude to Professor Keith O' hiobhaird, whose guidance and constructive
feedback helped us to improve the linguistic and academic quality of our thesis. In
addition, our sincere thanks go to all of our friends and participants in the
interviews for their supportive advice and helpful information.
Finally, we would like to thank Lahti University of Applied Sciences, where we
acquired all the professional knowledge and academic support for our thesis.
Nguyen Phu Minh Nguyen & Nguyen Quynh Anh
Question and Objectives
Research approach and Strategy: Design Science
Guideline 1: Design as an Artifact
Guideline 2: Problem Relevance
Guideline 3: Design Evaluation
Guideline 4: Research Contributions
Guideline 5: Research Rigor
Guideline 6: Design as a Search Process
Guideline 7: Communication of Research
Research Method
Scope and Limitation
Validity and Reliability
Data Collection
Data Analysis
OSI Model
Network Address Translation
Features of IPv4
Features of IPv6
Introduction to IPv6
IPv6 New Features
IPv4 and IPv6 Comparison
Research Data
Interviews Data
Documents Data
Network Infrastructure
Management Issues
Method 1 - Dual Stack IPv4/IPv6 Devices
Method 2 – Translation
Method 3 – Tunneling
Business Side
Technical Side
Stages of Readiness
Enterprise Network Design
Addressing Plan
Implementation Peformance
Dynamic Host Configuration Protocol (DHCP)
Open Shortest Path First (OSPF)
Border Gateway Protocol (BGP)
Virtual Private Network (VPN)
Security Establishment
Research result
Limitation and Further Study
Application Level Gateway
Address Resolution Protocol
Adaptive Security Appliance
Border Gateway Protocol
Chief Executive Officer
Chief Information Officer
Cisco Packet Tracer
Central Processing Unit
Chief Technology Officer
Dynamic Host Configuration Protocol
Demilitarized Zone
Domain Name System
Dual Stack Transition Mechanism
File Transfer Protocol
Internet Assigned Number Authority
Internet Control Message Protocol
Internet Engineering Task Force
Internet Message Access Protocol
Internetwork Operating System
Internet Protocol
IP-The next Generation
IP security
IP version 4
IP version 6
Information System
Intra-Site Automatic Tunnel Addressing Protocol
International Organization for Standardization
Internet Service Provider
Information Technology
Layer 2 Tunneling Protocol
Local Area Network
Internet Control Message Protocol for IPv6
Media Access Control
Maximum Transmission Unit
Network Address Translation
Open Systems Interconnection
Open Shortest Path
Personal ComputerFirst
Private Internet eXchange
Post Office Protocol version 3
Point-to-Point Tunneling Protocol
Quality of Service
Request For Comments
Regional Internet Registries
Stateless IP/ICMP Translator
Small to medium-sized enterprise
Simple Mail Transfer Protocol
Secure Sockets Layer
Transmission Control Protocol
User Datagram Protocol
Virtual Local Area Network
Voice over IP
Virtual Private Network
Wide Area Network
World Wide Web
FIGURE 1. Organizational design and information systems design activities
(Hevner, et al. 2004) .................................................................................................... 5
FIGURE 2. Data analysis .......................................................................................... 13
FIGURE 3. Network address translation (Cisco, Cisco IOS Network address
translation 2004). ....................................................................................................... 20
FIGURE 4. Static NAT (Tyson 2001) ..................................................................... 21
FIGURE 5. Dynamic NAT (Tyson 2001)................................................................ 22
FIGURE 6. Overloading NAT (Tyson 2001) .......................................................... 22
FIGURE 7. Subnetting (Lowe 2005) ....................................................................... 28
FIGURE 8. Subnet mask (Lowe 2005) .................................................................... 29
FIGURE 9. IPv4 free pool allocation (ARIN 2010) ............................................... 30
FIGURE 10. IPv6 neighbor discovery protocol ...................................................... 37
FIGURE 11. Virtual Local Area Network (VLAN)................................................ 47
FIGURE 12. Network Address Translation (Odom, Healy and Donohue 2009). . 48
FIGURE 13. Virtual Private Network ...................................................................... 50
FIGURE 14. Different transition technologies (Subramanian 2003) ..................... 56
FIGURE 15. The structure of Dual stack model (Oracle Corporation 2001). ....... 59
FIGURE 16. IPv4 – IPv6 dual stack operation (Cisco, The ABCs of IP version 6
2010)........................................................................................................................... 60
FIGURE 17. Translation method model (Microsoft, Technet 2012) ..................... 60
FIGURE 18. SIIT Model (Vienna University of Technology 2012) ..................... 62
FIGURE 19. Deployment of IPv6 using NAT-PT (Cisco, The ABCs of IP version
6 2010) ....................................................................................................................... 63
FIGURE 20. Bump in the Stack model (TechWeb 2009) ...................................... 64
FIGURE 21. Tunneling transition method (H3C 2003) ......................................... 65
FIGURE 22. 6over 4 model (Microsoft 2011) ........................................................ 66
FIGURE 23. DSTM model (Wedel 2008) ............................................................... 67
FIGURE 24. 6to4 Automatic Tunneling model ...................................................... 68
FIGURE 25. Teredo method (Microsoft 2011) ....................................................... 69
FIGURE 26. Tunnel Broker model (Netnam Ltd. 2011) ........................................ 70
FIGURE 27. Headquarter network structure model ................................................ 84
FIGURE 28. Branch 1 network structure model ..................................................... 85
FIGURE 29. VPN users ............................................................................................ 86
FIGURE 30. The whole network sructure model .................................................... 87
FIGURE 31. Ping from client computer to database server ................................. 112
FIGURE 32. Ping from DHCP server to client laptop .......................................... 113
FIGURE 33. Ping from client compurter to database server with Ipv6 ............... 116
FIGURE 34. Ping from client computer to database server with IPv6 ................ 117
FIGURE 35. DHCPv4 Configuration .................................................................... 118
FIGURE 36. Ping from PC on ISP3’s router to Web server in Headquarter ...... 124
FIGURE 37. Ping from VPN laptop to Database server in headquarter.............. 126
FIGURE 38. Show IPSec ........................................................................................ 128
FIGURE 39. Ping from PC of ISP3’s router to Mail server using IPv4 .............. 129
FIGURE 40. Ping from PC of ISP2’s router to Database server using IPv6....... 129
FIGURE 41. Pre-configured model........................................................................ 130
FIGURE 42. Configured model.............................................................................. 131
TABLE 1. Seven layers of OSI model (adapted from Balchunas 2007; OSI n.d.)18
TABLE 2. Internet protocols in the range of OSI model layers (Ford, et al. 1999)
.................................................................................................................................... 19
TABLE 3. IPv4 header (Ford, et al. 1999) .............................................................. 23
TABLE 4. IPv4 format .............................................................................................. 25
TABLE 5. IPv4 classes (Microsoft 2011; Mitchell n.d.) ........................................ 26
TABLE 6. IPv6 header .............................................................................................. 32
TABLE 7. General format of IPv6 ........................................................................... 34
TABLE 8. Management issues ................................................................................. 51
TABLE 9. Dual Stack (Nokia n.d.) .......................................................................... 57
TABLE 10. Summary of three methods .................................................................. 71
TABLE 11. Rank description ................................................................................... 80
Since the birth of Internet in 1960s (Cerf 1993), it has completely change the way
of communications forever. With its capabilities, the Internet has already become
a world-wide broadcasting capability, a mechanism for information dissemination,
and a medium for collaboration and interaction between individuals and their
computers regardless of geographic location (Leiner, et al. 2009). Nevertheless,
there is still no model which valuing companies' Internet efforts correctly, even
though the Internet's phenomenal impact on business and its reach across all
sectors are uncountable. (Afuah and Tucci 2001). Besides, according to its nature
in the structure of Internet, the TCP/IP has also played an important role in the
global expansion of communications. As a result, the more users join the Internet,
the better it would be to spread knowledge in every field around the world.
However, this is also the problem as the IP address is not unlimited and the
Internet community is witnessing the exhaust of IPv4 not year by year but day by
day, which calls for a proper solution. The first group of Internet users that would
be affected is internet service providers (ISPs), large enterprises, companies, etc.
The reason is that they hold the most number of IPv4 for operation and
management and before the IPv4 runs out, they will need an appropriate act to
handle the exhaustion, and otherwise, the collapse of the worldwide Internet is
foreseeable (Huston 2008).
This study is conducted to answer the question which is the best method for large
enterprise networks to transit from IPv4 to IPv6. Currently, there have been many
papers, documents, or reports about IPv4 exhaustion; the invention of IPv6 and
the way administrators can apply IPv6 to existing networks, known as transition.
However, there are still few or nearly no documents for applying the transition
from IPv4 to IPv6 in a large enterprise networks with many different geographic
branches around the world. Therefore, with this thesis, we would like to give our
suggestion on a solution for a complete implementation of IPv6 into large
enterprise network with no influence on its current operation. Furthermore, this
thesis does not only focus on the technical aspects but also the management side.
It would provide an insight into the importance of IPv6 transition, as well as a
careful analysis on its influence to the enterprise network and its operation. For all
the information above, this thesis could be used as a source of reference for
network administrators, board of directors, information executives, or students
and network researchers who have an interest in the network communication and
would like to join the community of IPv6.
Therefore, with the topic “Transition from IPv4 to IPv6: The best method for
large enterprise networks”, we will have two main parts: the theoretical and the
practical. For the first part, we would propose the research question, our
approaches with the qualitative method, and also the data collection. In addition,
we would give an introduction about computer network, internet protocol,
especially all the main features of IPv4 and IPv6 to indicate the differences
between them. And for the second part, we would like to apply the DesignScience method to analyze the current network infrastructure, IPv6 readiness in
large enterprises to acknowledge the reasons and willingness for changing to
IPv6. Moreover, this method is also be deployed in the IPv6 implementation for
its effectiveness and risks.
Firstly, for the theoretical part, in Chapter 1, we would like to express the
background and aims, along with the goal and scope of the thesis. Besides, a study
is the combination of both theory and practice via change and reflection in a
problematic situation within a framework. It is a process consisting of researchers
and practitioners working together on a certain cycle of activities, including
problem diagnosis, action intervention, and reflective learning (Lee 1999; Davis
and Olson 1985). Therefore, Chapter 2 and 3 would handle mainly the research
methods and data framework consisting of research questions and objectives,
research approach and strategy, scope and limitation, validity and reliability, data
collection and analysis. Chapter 4 also contains information about the Internet
Protocol, known as IP. In this part, we would provide an insight into the network
model with layers, the structure and features of both IPv4 and IPv6, and the
difference between the old and new address format.
Secondly, for the empirical part, in Chapter 5, we would perform a business
network analysis to understand the current network infrastructure in large
enterprises. Chapter 6 grabs a thorough view on the IPv6 readiness and suggestion
for the current infrastructure to be ready for the IPv6 implementation. Then
Chapter 7 would contain the evaluation of current transition methods, which
becomes the base for choosing the right and suitable IPv6 implementation. The
Chapter 8 is the place where we perform the practical implementation into real
networks and test our methods for large enterprise networks with the network
model as required from the design science method. As we all have known
information systems and the organizations they support are complex, artificial,
and purposefully designed. They are composed of people, structures, technologies,
and work systems. Design science, as the other side of the IS research cycle,
creates and evaluates IT artifacts intended to solve identified organizational
problems. Such artifacts are represented in a structured form that may vary from
software, formal logic and rigorous mathematics to informal natural language
descriptions (Lee 1999; Davis and Olson 1985). Those artifacts are broadly
defined as constructs, models, methods, and instantiations to meet with the
business strategy, information technology strategy, organizational infrastructure
and information system infrastructure. Finally, the conclusion in chapter 9 would
include an overview of the thesis, innovations and limitations of the methods, as
well as the result analysis from the implementation.
This chapter provides the research question and research methodology of our
study. Research approach will be presented in detail so that readers will
comprehend our research model.
Question and Objectives
The most important and also initial step of a thesis is to define the research
question. Based on the nature of that question, proper methods will be applied to
find the expected answers. The research question of this thesis is: “Transition
from IPv4 to IPv6: What is the best method for large enterprise networks?”
These following actions are taken to find the answers:
Conducting a thorough literature review
Interviewing some specific large companies which have deployed IPv6
Analyzing their experiences and attitudes towards IPv6 deployment
Analyzing and comparing some transition methods to find the best one
Building a network model and testing the method
Concluding the result (inductive)
The results from above actions are main objectives of this thesis, which include:
Acquiring thorough understanding about IP as well as definitions, ideas,
and arguments IPv6 transition methods.
Getting better understanding of IPv6 deployment in real life project and
experiences from companies who had deployed IPv6.
Proposing the best method for transitions from IPv6 to IPv4 for large
enterprise networks.
The type of this study’s research question is “solution” which means to find a way
to solve a problem. Therefore, the purpose of this paper is to define and test the
most applicable method for large enterprise network to transit their current IPv4
network to IPv6.
Research approach and Strategy: Design Science
Design science, as the other side of the IS research cycle, creates and evaluates IT
artifacts intended to solve identified organizational problems. Such artifacts are
represented in a structured form that may vary from software, formal logic and
rigorous mathematics to informal natural language descriptions (Lee 1999; Davis
and Olson 1985). Those artifacts are broadly defined as constructs, models,
methods, and instantiations to meet with the business strategy, information
technology strategy, organizational infrastructure and information system
FIGURE 1. Organizational design and information systems design activities
(Hevner, et al. 2004)
Therefore, the reason for using design science method is that it is a problem
solving process. The fundamental principle of design-science research combines
seven guidelines whose knowledge and understanding of a design problem and its
solution are acquired in the building and application of an artifact. That is,
design-science research requires the creation of an innovative, purposeful artifact
(Guideline 1) for a specified problem domain (Guideline 2). Because the artifact
is "purposeful," it must yield utility for the specified problem. Hence, thorough
evaluation of the artifact is crucial (Guideline 3). Novelty is similarly crucial
since the artifact must be "innovative," solving a heretofore unsolved problem or
solving a known problem in a more effective or efficient manner (Guideline 4). In
this way, design-science research is differentiated from the practice of design.
The artifact itself must be rigorously defined, formally represented, coherent, and
internally consistent (Guideline 5). The process by which it is created, and often
the artifact itself, incorporates or enables a search process whereby a problem
space is constructed and a mechanism posed or enacted to find an effective
solution (Guideline 6). Finally, the results of the design-science research must be
communicated effectively (Guideline 7) both to a technical audience (researchers
who will extend them and practitioners who will implement them) and to a
managerial audience (researchers who will study them in context and practitioners
who will decide if they should be implemented within their organizations) (Lee
1999; Davis and Olson 1985).
Guideline 1: Design as an Artifact
The result of design-science research in IS is, by definition, a purposeful IT
artifact created to address an important organizational problem. It must be
described effectively, enabling its implementation and application in an
appropriate domain. For this reason, models for the three main methods used in
the transition from IPv4 to IPv6 will be created. However, this will not be applied
for small and medium companies but we aim for large businesses with over 250
employees along with a large network. This would help defining the ideas,
practices, technical capabilities, and products through which the analysis, design,
implementation, and use of new implemented Ipv6 information systems. On the
other hand, it also demonstrates feasibility both of the design process and of the
designed product.
Guideline 2: Problem Relevance
The objective of research in information systems is to acquire knowledge and
understanding that enable the development and implementation of technologybased solutions to heretofore unsolved and important business problems. Design
science approaches this goal through the construction of innovative artifacts
aimed at changing the phenomena that occur (Venkatesh 2000 according to
Hevner, et al. 2004).
From our point of view, business organizations are goal-oriented entities existing
in an economic and social setting. The design of organizational and interorganizational information systems plays a major role in enabling effective
business processes to achieve these goals. Because organizations spend billions of
dollars annually on IT, only too often to conclude that those dollars were wasted
(Keil 1995; Keil et al. 1998; Keil and Robey 1999 according to Hevner, et al.
2004). To deal with this matter, a survey will be conducted carefully and strictly
with selected enterprises possessing large networks. At first, a questionnaire will
be sent to get the results about the current network, IT expenditure, the success
and failure of IPv6 deployment, affected factors and so on. These cases will be
analyzed thoroughly to opt out the best method for the transition. From the
analysis, a design will be simulated according to the specific condition to produce
the best result which suits all networks.
Guideline 3: Design Evaluation
The utility, quality, and efficacy of a design artifact must be rigorously
demonstrated via well-executed evaluation methods (Hevner, et al. 2004). The
business environment establishes the requirements upon which the evaluation of
the artifact is based. This environment includes the technical infrastructure which
itself is incrementally built by the implementation of new IT artifacts. Thus,
evaluation includes the integration of the artifact within the technical
infrastructure of the business environment. A design artifact is complete and
effective when it satisfies the requirements and constraints of the problem it was
meant to solve. To fulfill this requirement, a test will be conducted thoroughly
before and after implementation to check all the new features and also the
integration with the old network. It would consist of many things such as: network
performance, quality of services, compatibility, common services which are
WWW, DNS, DHCP, routing, security, mail exchange, VPN, VoIP, etc…These
kinds of test are summarized in the following table.
Guideline 4: Research Contributions
Effective design-science research must provide clear contributions in the areas of
the design artifact, design construction knowledge (i.e., foundations), and/or
design evaluation knowledge (i.e., methodologies). One or more of these
contributions must be found in a given research project (Hevner, et al. 2004).
The Design Artifact - The artifact must enable the solution of heretofore unsolved
problems. From this thesis, our artifact would be the new design model for the
transition from IPv4 to IPv6 to obtain the best results.
Foundations - The creative development of our method of transition IPv4 to IPv6
would extend and improve the existing foundations in the network knowledge
However, we would also set the criteria for assessing contribution focus on
representational fidelity and implement ability. This new information system
themselves is the model of the IPv6 business network. This design must be
"implementable". Beyond these, however, the design science research must
demonstrate a clear contribution to the business environment, solving an
important, previously unsolved problem.
Guideline 5: Research Rigor
Design-science research demands that the research applies rigorous methods. This
research’s main purpose is finding the best method to transit IPv4 system to IPv6
for large-scale network. Various organizations have defined and tested many
methodologies. Our research focus on transition technique that come in one of
three forms: dual stacks, tunneling, and translation. These transition mechanisms
have been proposed by IEFT (Internet Engineering Task Force). (Daniel
G.Waddington 2002, 139). According to the questionnaire conducted in this
research on some large organizations network, the testing models will be built
based on those transition methodologies stated above. Artifact model is going to
be constructed on the basic of those three existing mechanism.
Guideline 6: Design as a Search Process
Design-science is a process searching for the best solutions for realistic problems
(Hevner, et al. 2004). Our research identifies three main transition mechanisms
from IPv4 to IPv6, which are: dual stacks, tunneling, and translation. The
research will focus on the design of best transition method that based on those
mechanisms. First, the research is going to find out the business needs and
attributes of current network infrastructure and then to design a solution to satisfy
the requirements. Cost and benefits of the proposed solutions will be discussed
Guideline 7: Communication of Research
Design-science research should be presented in a way that both technologyoriented audience and management-oriented audience can take advantages of. Our
research on transition of IPv4 to IPv6 will present an artifact and technical issues
related for building it. Critical factors that have influences on the implementation
will also be stated in our paper. Testing and evaluation process is going to be
documented properly for further development purposes.
On the other hand, the research is based on the needs of realistic organizations.
Cost and benefits of the solution provided by this paper will be discussed to help
the decision-making process. Management-oriented audience can find information
on resources needed as well as possibility to apply the artifact on their own
Research Method
Quantitative methods are often used to process random sampling data into
numbers and statistics (Lichtman 2006). Quantitative research concerns with
testing hypotheses, considers cause and effect, and calculates the size of a
phenomenon of interest (Johnson and Christensen 2008). The end-results are
usually statistical report including both descriptive and inferential statistics.
Descriptive method summarizes and presents data in an informative way while
inferential method generalizes about a population based on a sample. As such
nature of quantitative method, data collection often includes closed-ended
questionnaire, surveys that classify various experiences into categories, recording
numerical data through observing events etc… (University of Wisconsin-Eau
Claire n.d.)
On the other hand, the purpose of qualitative method is to understand and interpret
processes underneath an observed event and evaluate people’s perception
involved in the event (InSites 2007). It concerns people, objects, words, images
not numbers and statistics. In qualitative research, personal feelings and
experiences are analyzed. Qualitative research is often used to construct a new
theory from the data collected. For that reason, qualitative data collection methods
are interviews with open-ended questions, observation, and document review.
(University of Wisconsin-Eau Claire n.d.) This paper aims to study the current
network conditions of some large enterprises as well as their attitude toward the
transition from IPv4 to IPv6. Thus, qualitative research method is applied to this
thesis. As observation was unable to be carried out, interviews and document
review were done as data collection method in this paper.
Scope and Limitation
The scope of this thesis mainly discusses the most applicable transition method
from IPv6 to IPv4 for enterprises with large network. The presentation of the
method includes literature review, advantages, and configurations as well as
simplified model of the method. As this thesis aims at large network, large
enterprises with big network traffic may find it more useful than small and
medium sized network. There are some transition procedures which may not be
suitable for small and medium sized networks due to their complexity. Therefore,
this thesis is most applicable and limited to large network.
Validity and Reliability
Presently, there are various definitions of validity and reliability in qualitative
research method from perspectives of many different researchers. In this thesis,
the understanding of validity and reliability will be considered and measured by
the idea of trustworthiness according to Mishler (2000). Lincoln & Guba (1985)
explained it as being able to establish confidence in the findings. Moreover,
Johnson (1997) stated that reliability and validity can also be understood as
“defensible”. (Golafshani 2003). Multiple persepectives from various sources
shoulbe be compared and tested before the conclusion to strengthen the results
and enhance “trustworthiness” (Yin 2011, 20).
This study relies on a variety of sources, which are from technical papers of
leading telecommunication companies. Conclusion is drawn in reference to those
All the enterprises chosen had carried out IPv6 deployment. Those enterprises
chosen are all large network enterprises which falls into class B to class A
according to IP classes which means large network. All the interviewees are
people who were in charge of or involved in IPv6 deployment in their companies.
All data sources are listed in reference and can be verified.
Data collected will be analyzed by proper methods in the right procedures so that
the study remains stability, reproducibility and accuracy. It means that data can be
analyzed and classified in the same way over a period of time. (Palmquist n.d.)
Data Collection
We all know that multiple sources are more reliable than single reference. They
enhance the validity and reliability of the thesis. This thesis research collected
data by interviews with several specific organizations and document review.
Document review or document analysis is the procedure of examining and
evaluating published documents systematically in both printed and electronic
form. As well as other qualitative data collection methods, data must be evaluated
and explained in order to develop knowledge and evidence, which can support the
research. (Corbin and Strauss 2008). In addition, documents forms are varied.
They consist of books, newspapers, journal articles, advertisements, agendas,
memos of meetings, letters, maps and charts, press releases, program proposals,
applications forms, radio and TV transcripts, reports of organization, surveys,
etc... (Bowen 2009). The procedure of analyzing includes searching, choosing,
interpreting, and synthesizing data. Data taken from the documents can be
quotations or extraction are organized and analyzed throughout content of the
research. (Labuschagne 2003). This research paper contained extensive technical
information which was synthesized from various sources, especially documents
from leading networking organizations such as Cisco and Microsoft.
Interview is a commonly used research method. In qualitative research,
researchers try to understand not only the fact of the subjects but also the meaning
of their experience. The process of interviewing is to find out different point of
view, problems, solutions, and attitudes of interviewees within the main theme of
the research. (Rubin and Rubin 1995). There are several types of interview such as
closed interview, standardized interview, and conversational interview. In this
thesis, standardized, opened – ended interviews was conducted with people in
charge of IPv6 deployment and network maintenance staffs to find out their
different practical experiences on this subject. The questions are made so that
answers are open-ended; which means participants can fully express their points
of views and experiences (Turner 2010).The same questions were provided to the
interviewees to make the process of analyzing and comparing more easily. (Israel,
et al. 2005, 308). Due to graphical difficulties, all the interviews were done via
emails and telephone. The questionnaire can be found in the Appendix 1.
Before the interviews were conducted, emails concerning the issues were sent to
all the appropriate organizations asking for permissions. Unfortunately, as always
happening when conducting a research, not many have answered back or given
permissions for the research. The list of organization who agreed to participate in
this bachelor study is in Chapter 5.
Data Analysis
FIGURE 2. Data analysis
The process of analysis in this paper is inductive approach. As we can see from
Figure 2 above, data collected from document review and interviews will be
processed to draw a theory. Theory is concluded based on the data.
As we compare all the technical aspects of current transitions methods and from
real-life experiences of interviewees, the best transition method, which can be
applied to large enterprise network, can be found out. The process of transition
that is best for enterprises will also be concluded based on the experiences of
interview participants.
There are various methods for qualitative data analysis. In this thesis, the method
“content analysis” is used. This method classifies themes and ideas taken from
data into groups. This method is theory driven, which means that theory decides
the subject we look for. There are some rules of content analysis but most
important is that categories must be inclusive and mutually exclusive. (Weber
1990). By applying this method, differences, intensions and trends can be detected
via looking directly at the texts and transcripts. Uses of content analysis enable
behavioral responses of communicators or personal feelings to be described.
(Palmquist n.d.).
We will look into the documents and interview transcripts to find out the main
subject. Answers to the same question from different interviewees will be
compared to search for mutual view, how the ideas related in different situations
as well as different points of views. The same process is applied to data from
document review. Important phrases or words are highlighted and coded.
Therefore, a set of data groups will be formed. This procedure is done several
times to avoid leaving vital information out.
The first thing to know is the definition of a network. A network is a group of
computers linked together via communication devices and transmission media. A
computer is online when it is connected to a network, or log on. On the other
hand, it is offline or log off when it is disconnected. A computer, which is
connected to a computer network, is called a node (Lowe 2005, 36). The main
purpose of connecting different computers together is that they can exchange
resources i.e. hardware, applications, data, and information. All networks need
specialized network hardware and applications to work. Hardware consists of
cables, network interface card, network switch, routers, repeater etc. In general, all
networks are built from these following parts:
Server computers are computers that share resources such as printers, scanners;
disk storage, and network services i.e. Internet access. The servers normally run
specialized network operating system and network service software.
Client computers are all the other computers on the network, which are not server.
End users use client computers to request and access the resources on the network
provided by server
If a computer wants to connect to the network, it needs a NIC, a Network Interface
Card. This card enables computers to physically connect to the network via cable.
It is also referred as Ethernet card or network adapter. This card is attached inside
the computers.
Cables do not actually connect computers to each other. In fact, cables connect
computers to a switch. The switch, in turn, connects the rest of network together.
Switches can be connected together to make a larger network.
Finally, to make a network actually work, network software is required. For
clients as well as servers, specialized software is installed in order to share the
resources on the network. (Lowe 2005).
Presently, the world’s largest computer network is the Internet.
“The Internet is a worldwide collection of networks that connects million of
business, government, agencies, educational institutions, and individuals.” (Gary
B.Shelly, 2012, pp. 10-12)
Each computer on the Internet must have a unique address, which marks it as
different to other computers on the Internet. This special address is called IP,
which stands for Internet Protocol. Network protocol administrates all
communication activities. It defines order and format of messages transmitted
among network devices along with the actions upon those transmissions. (Jim
Kurose 2007). At this time, there are two version of IP address: IPv4 (Internet
Protocol version 4) and IPv6 (Internet protocol version 6). A question may come
up. What happened to IPv5? Raffi Krikorian from had given
us the answer. Back to the end of 1970’s, a protocol for experimental transmission
of voice, video, and distributed simulation called ST, the Internet Stream Protocol
was made. It was implemented at places like IBM, Apple, and Sun. That protocol
can be given the name version 5. Therefore, the next generation of IP is now IPv6.
(Krikorian 2003). Nowadays, IPv4 addresses are so common that the term IP is
understood as IPv4. Details features of IPv4 and IPv6 will be discussed later in
this chapter.
OSI Model
Today, all of the networks are built based on the frame of Open Systems
Interconnection (OSI) model. OSI was issued in 1984 by the International
Organization for Standardization (ISO). It is a standard for international
communication that explains seven abstract layers of networking framework for
protocol. The OSI model describes the way messages should be transmitted
between any two points in the network. The main purpose of this model is to
make it easy to communicate between different hardware and software system
with different underlying architectures. Network protocols allow entities in a host
to communicate with equivalent entities at the same layer in another host. Each
layer interacts directly only to the layer under it and provides facilities just for the
layer above it. (Ford, et al. 1999). The figure below explains seven layers of the
OSI model.
TABLE 1. Seven layers of OSI model (adapted from Balchunas 2007; OSI n.d.)
• This layer provides the interface
between the network and user
applications. User interact directly to this
layer. This layer does not include
computer application software but
contain web-browsers, email clients, FTP
• This layer controls the format of data
being transmitted. It makes sure that
data will be understood by other sending
and receiving device as well as other
layers. This layer also control the
encryption and compression of data.
• This layer sets up, manages and
terminates the communication session
between computers.
• This layer controls data segmentation,
data flow and provides error checking
recovery of data before and after
• This layer concerns with the processes
logical addressing and routing data
across the network hierarchy.
• This layer explains the logical way that
data being transmitted reliably. It deals
with the data framing and encapsulation.
• This layer defines the physical network
equipment transferring data across the
network i.e. cables, wires, network cards
Network protocols spread the entire OSI model. Table 2 shows some network
protocols equivalent to each OSI layer.
TABLE 2. Internet protocols in the range of OSI model layers (Ford, et al. 1999)
The IP is at layer 3 of OSI model, which is the Network layer. It contains
addressing information and other information which allows data packets to be
Network Address Translation
Network Address Translation, as known as NAT, is a technique that operates on
the router to connect two networks together. NAT makes the router function as an
agent between the private (or “inside”) and the public, the Internet (or “outside”)
(Cisco, Cisco IOS Network address translation 2004). It means that a globally
unique IP address can represent a whole group of computers (Tyson 2001).
Let’s imagine NAT as a receptionist in an office. An officer may instruct the
receptionist not to forward all the messages sent to him but only from people he
requests. Now, when someone calls the main number to the office, which is the
only official number, the receptionist will check to make sure that officer is
expecting the call from this person. Only then she will forward the caller to the
officer. (Tyson 2001).
Similarly, the NAT device uses a single unique IP address to represent the inside
network to the Internet. Inside the network, each computer can have any IP
address. When a packet of data is sent, the NAT translate the private IP to public
IP. It keeps track of the sending packets so that it knows who is expecting for the
reply from which source then match up the right incoming packet to the right host.
(Tyson 2001). Figure 3 below demonstrates above explanation.
FIGURE 3. Network address translation (Cisco, Cisco IOS Network address
translation 2004).
NAT works in several ways as described below.
Static NAT
As can be seen from Figure 4, in static NAT, the host with the IP address of will always be translated to In static NAT, an
unregistered private IP address will be mapped to a registered public IP address on
one-to-one scale. This technique comes in handy when outside network need to
access a device.
FIGURE 4. Static NAT (Tyson 2001)
Dynamic NAT
Figure 5 demonstrates that the host with the IP address will be
translated to the first available IP address in the range. In dynamic NAT, a private
IP address will be assigned to an available registered public IP address from a
range of registered addresses.
FIGURE 5. Dynamic NAT (Tyson 2001)
In Figure 6, each host in the private network is translated to the same public IP
address which is but assigned to different ports. Overloading is a
form of dynamic NAT which maps several private IP addresses to a same public
IP address by assigning different port numbers. (Tyson 2001).
FIGURE 6. Overloading NAT (Tyson 2001)
Features of IPv4
IP is a standard protocol with STD number 5 that is documented in RFC 791 of
IETF (Internet Engineering Task Force). Its main function is to deliver data
packets between network devices. IP provides an unreliable, connectionless and
best-effort delivery of packet or also called datagrams through Internet. In
addition, IP also provides fragmentation and reassembly of packets into original
message. (Ford, et al. 1999)
An unreliable connectionless communication is a data transmission method in
packet switching network, which transmit data packet in on direction without
checking the existence or availability of the destination. In this method, each data
packet has a header, which carries sufficient information to deliver the packet to
its destination (Microsoft 2011).
Best-effort means that the data delivered can be repeated, lost, corrupted or
broken. Data is not guaranteed to be delivered (Microsoft 2011).
IPv4 packet header format
TABLE 3. IPv4 header (Ford, et al. 1999)
Each field of the header is explains as following.
Version points out the IP version in use. The value of this field is 4 as the name
IHL (IP Header Length) is the length of the header in 32 bits word and points to
the beginning of the data. The minimum value of the header is 5.
Type of service indicates how the upper-layer protocol will treat and handle the
data packet with different levels of priorities.
Total Length is the length of the entire packet including header and data. It is
measured in octets/
Identification is a value that identified the current packet which helps in
assembling the fragment of the packet.
Flags field has 3 bits that allow the router to fragment packet or not.
Fragment Offset contains 13 bits indicates which packet a fragment belongs to.
Time-to-Live prevents the packet from looping forever. It shows the maximum
allowed time that the packet stays in the internet.
Protocol specifies which next layer protocol will be used after the IP processing is
Header Checksum is on the header only. Some of the headers field may change,
therefore this is computed each time the header is processed.
Source Address marks the sender.
Destination Address indicates the receiver.
Options support some other options i.e. security.
Data includes information of next layer.
(Ford, et al. 1999; RFC791).
IP addressing
The process of routing data packets within the Internet requires the IP addressing
scheme to let any two hosts to exchange information to each other. The IP address
is a unique number assigned to each host on Internet. It is represented by a 32-bit
binary value divided into four groups of eight bits (Ford, et al. 1999). This IP
address number consists of two main parts: The network number and the host
number. The network number identifies which network the host computer is
located. The host number identifies a specific host computer on that network.
(Ford, et al. 1999).
A typical IPv4 address is separated by dots and expressed in decimal format,
which is known as dotted decimal number or dotted decimal notation. (Gary
B.Shelly 2012, 110). In this format, each group of eight bits is called an octet,
which will be represented by a corresponding decimal value. Each octet value
ranges from 0 through 255. Table 4 below illustrates the basic format of an IPv4
TABLE 4. IPv4 format
An IPv4 address such as has its binary format as
00010001.10101100.11100000.00101111. It is not easy to remember such an
address; therefore, it is then assigned a unique name, which is resolved through
the Domain Name System (DNS). The address above will be translated into, which users will type into an address bar to access the website.
Classifying IP address
IPv4 addresses are categorized into five classes for use of different network size:
A, B, C, D and E. Classes A to C are use commercially while class D is used for
multicasting and class E is for experimental purpose. Which part of the address is
the network number decides the class. (Gary B.Shelly 2012). To determine which
class an address belongs to, the first octet is used as in the following table.
TABLE 5. IPv4 classes (Microsoft 2011; Mitchell n.d.)
The number of hosts is minus by 2 in each range because IETF reserved some
certain addresses for broadcasting, maintenance, and hosts etc (RFC5735).
Class A is normally used for large organizations with a big number of hosts while
Class C is suitable for small networks. Small-medium sized enterprises networks
must use Class B. The gap between Class C and Class B is rather larger. Many
enterprises have more than 245 hosts but far less than 65,543 hosts. Moreover, the
number of SMEs is increasing rapidly and there are not enough IP addresses to
provide them. The solution to this problem was solved through IP subnetting,
which allows the administrator to divide the network into subnets (or sub
Subnetting is a technique used to divide an IP network into several smaller
subordinate networks that can be called subnets. A subnet is a subordinate
network of a bigger Class A, B, or C network and under control of local
administrators. The outside network views the entire big network as a single IP
without knowing the detail of internal network structure. This technique helps
network administrators to create a much more flexible and efficient network with
more traffic capacity. Why it is said that subnetting provides extra flexibility for
the network administrators? We already know that for typical IPv4 classes, there
are merely three options for a network number length: 8 bits, 16 bits and 24 bits
corresponding for Class A, B and C. That leaves three choice of the host number:
254, more than 65 thousand and 16 millions. As mentioned before, SMEs that fall
into scale between 254 and 65 thousand find it difficult to have a right network
without wasting or have a shortage of IP addresses. Subnetting allows a portion of
host number of Class A, B or C to be used as sub network number, which makes it
much more efficient use of IP addresses. On the other hand, for performance
reason, subnetting is use to divided broadcast domain into smaller than even Class
C so that not one single domain must carry all the network traffic. (Lowe 2005,
364). Figure 7 demonstrates an example of subnetting.
FIGURE 7. Subnetting (Lowe 2005)
The network is assigned the IP address and a single broadcast domain
will carry all the traffic of this network. After subnetting, the first part of network
number was used to divide the network into 2 smaller ones, subnet 16 and subnet
32. The outside world still views the whole as a single It considers a
host at belongs to When a datagram is sent to that host,
the router will determine which subnet it belongs to by check the subnet part of
host number.
For “borrowing” from the host number, subnets can have any length of network
number instead of standard 8 bits, 16 bits or 24 bits. For the router to know which
part of host number was used for network number of subnets, a subnet mask is
needed. Subnet mask is a 32-bits number that looks like an IP address but actually
it has a completely different technical meaning. All the 1 in the binary format
indicate the bits for network number, and all the 0 indicate the bits of the IP
address that act as host number. (Lowe 2005, 364)
Figure 7 above has a 16-bit network with 4-bit subnet in addition will have a
subnet mask like this:
This makes the actual network number of subnet 20 and host number 12 bits. The
router will perform the AND operation to decide the network ID of an IP address
as figure 8.
FIGURE 8. Subnet mask (Lowe 2005)
Accordingly, the packet, which is sent to, will be routed to subnet
The subnet mask also normally represented in dotted decimal format.
(Lowe 2005; Ford, et al. 1999).
IPv4 space utilization
IP addresses are 32-bit binary numbers. Each number can be 0 or 1. Thus, the total
possible number of IP addresses can be 2 32, which equals 4,294,967,296 unique
values. Nevertheless, the actual usable value is ablout 3 billion as some of the
addresses are reserved for special purposes. (Gary B.Shelly, 2012, p. 110)
IPv4 addresses are managed through the Internet Assigned Number Authority
(IANA) who distributes large address block for five Regional Internet Registries
(RIRs) according to geographical territories. Until recent, the pool of free IPv4 is
now nearly running out.
FIGURE 9. IPv4 free pool allocation (ARIN 2010)
Figure 9 indicates that by the time of 3 rd February 2011, IANA assigned each RIR
its last block of /8 IPv4 addresses. It means that the free pool of IPv4 actually has
reached 0%. As the wheel must go on, Ip next Generation, which is Ipv6 is the
solution to the future of the Internet. The address size is increased from 32- bit
number to 128-bit number and represented in hexadecimal notation. The number
of address jumps to 2128 =
340,282,366,920,938,463,463,374,607,431,768,211,456. IPv6 deployment has
begun. (ARIN 2010).
Features of IPv6
In this sub chapter, the main features of IPv6 will be presented.
Introduction to IPv6
As from above, IPv4 has demonstrated its features to be useful both in the
implementation and operation. Furthermore, it plays an important part in every
network, from a local area network to the worldwide Internet. Nevertheless,
everything has two sides and IPv4 is not an exception. With the growth of
population and the development of technology, the demand for IPv4 addresses
becomes higher and higher day by day while the resource is running out.
Although private addresses have been long used to compensate for this problem, it
is just a temporary solution as the levitation of Internet-connected devices makes
sure that the public IPv4 addresses will soon be exhausted. Furthermore, the rise
of Internet and its users requires devices which play as backbone routers to
manage and support a great amount of routing tables consisting of over 70,000
routes across the world (Davies, 2002).
However, every problem has in it the seeds of its own solution. In response to
these matters, a new concept has been developed which is known as IPng (IP-The
Next Generation) or IPv6 (Internet Protocol version 6) along with its protocols
and support. Similar to IPv4, IPv6 is an Internet Layer protocol for packetswitched internetworking and provides end-to-end datagram transmission across
multiple IP networks. With many of its additional features, the IPv6 is supposed
to eventually replace the old IPv4 in every network without limitations (Deering
& Hinden, 1998). The main differences between IPv4 and IPv6 range from new
addressing space to built-in security. The following sections discuss each of these
new features in detail.
Streamlined header format
TABLE 6. IPv6 header
Version - 4-bit Internet Protocol version number = 6.
Traffic Class - 8-bit traffic class field.
Flow Label - 20-bit flow label.
Payload Length-16-bit unsigned integer: Length of the IPv6 payload, i.e., the rest
of the packe following this IPv6 header, in octets. (Note that any extension
headers present are considered part of the payload, i.e., included in the length
Next Header - 8-bit selector which dentifies the type of header immediately
following the IPv6 header. It uses the same values as the IPv4 Protocol field.
Hop Limit - 8-bit unsigned integer. Decremented by 1 by each node that forwards
the packet. The packet is discarded if Hop Limit is decremented to zero.
Source Address - 128-bit address of the originator of the packet.
Destination Address - 128-bit address of the intended recipient of the packet
(possibly not the ultimate recipient, if a Routing header is present).
The new form of IPv6 header aims to reduce header overhead by relocating
unimportant fields and option fields to extension headers which are positioned
right after the IPv6 header. As a result, this enables the simplified IPv6 header to
be processed more efficiently at intermediate routers. However, the IPv6 protocol
is incompatible with the IPv4 protocol. Therefore, a network connected device
(host or router) needs to apply an implementation of both IPv4 and IPv6 in order
to identify and process two kinds of header formats (Hagen, 2006).
IPv6 New Features
Expanded address space
As we have mentioned above, the main reason for the invention of IPv6 is the
shortage of IPv4 resources. Despite its usefulness and flexibility, IPv4 combines
of 32 bits, which can only create a total of 2^32 (4,294,967,296) addresses.
Meanwhile, with new technologies, IPv6 contains 128 bits, and as calculated
above, the new address space supports a number of 2^128
(340,282,366,920,938,000,000,000,000,000,000,000,000) addresses, which is
2^96 times larger than IPv4 address resources. From those calculations, there has
been a saying that “With IPv6, nearly every object in the world can obtain an
address for its own”. As a result, this expanded address range of IPv6 can be
variously applied from the Internet backbone (interconnected networks, core
routers) to individual subnets (hosts, end devices) within an organization.
Furthermore, it also makes address-conservation techniques, such as NATs,
become unnecessary, which gained widespread deployment as an effort to
alleviate IPv4 address exhaustion (Microsoft, 2005).
Effective and organized infrastructure for addressing and routing
Along with the expanded address space comes the hierarchical address format.
This is also a new and important aspect of IPv6. Unlike IPv4 hierarchical address
consists of network, subnet, and host components, IPv6, supported with 128-bit
addresses, provides globally unique and organized addressing known as prefixes
(address classes in IPv4).
TABLE 7. General format of IPv6
Global routing prefix
Subnet ID
Interface ID
n bits
m bits
128-(n+m) bits
Global routing prefix: a value (typically hierarchically structured) assigned to a
Subnet ID: an identifier of a link within the site
Interface ID: a unique identifier for a network device on a given link (usually
automatically assigned).
Within the IPv6 contains a range of global addresses, whose purpose is to form an
effective, organized, and downsized infrastructure for routing that discusses the
conventional development of multiple levels from Internet service providers.
Appropriately, backbone routers contain routing tables which are much smaller in
the IPv6 Internet. (IBM, 2008)
Advanced address configuration
In order to reduce complexity in the configuration of the host, IPv6 is equipped
with new functions to uphold two ways of address configuration:
Stateful address configuration: a host receives IPv6 address along with optional
configuration specifications from a server named DHCPv6 via a UDP link.
However, in the circumstance that DHCPv6 server does not exist on that link,
there will be some special nodes acting as relay agents to help transmit these
request packets from the host to other DHCPv6 servers in the nearby link or
forward to the next relay agent.
Stateless address configuration: with this mechanism, manual configuration of the
hosts or additional servers is no longer needed. In addition, it helps to minimize
the configuration of routers. It also gives way for a host to form its own addresses,
known as link-local addresses, by utilizing local and advertised information from
routers. This means hosts on the same link can automatically create themselves
link-local addresses and communicate with each other with manual configuration
or in the absence of a router (Cisco, 2010).
Built-in security
Since the birth of Internet up to today, security has always been an important issue
when there are an increasing number of hackers, equipped with networking
knowledge, trying to prove themselves. The Internet once was a network without
intermediary gateways or routers or security (an end-to-end network). After that,
as the network develops, there raises a question “How to ensure the safety of
private data when transmitting on a public network?”. Under the circumstances,
gateways, firewalls, and local network isolation have become available all over
the world as a reply to this question. Despite these efforts, data privacy and
security continues to be a prominent issue and no complete solution has been
found. However, in conjunction with the invention of IPv6, whose main purpose
is to overcome the IP address depletion, the most propitious answer for the data
protection has been found, known as built-in security (IPSec) (RFC 1825 Security Architecture for the Internet Protocol).
IPSec is a framework of open standards setting network security policies for
transmitting packets in a network. It is developed to function in the layers between
the physical layers and the application layer. This ensures all data encapsulated in
the packet to travel safely among stations such as routers. Therefore, in IPv6
structure contains a protocol suite requirement to support for IPSec, increase
network security and contribute to interoperability among various IPv6
deployments. However, the IPSec in IPv6 is located in the extension headers,
which makes the use of IPSec is optional. Consequently, security may be
improved thanks to the built-in security in IPv6 protocol, the total protection still
lies in the hands of human beings (Arora & Desai, 2008).
Better support for Quality of Service
Quality of Service (QoS) is an old term commonly used in modern networks. In
IPv4 networks, it is known as "best level of effort" service. However, it has a
weakness that IPv4-implemented networks are unable to tell the difference if data
that are time-sensitive (streaming video or audio) or not (file transfer). In case a
packet is lost when transmitting, the TCP identifies the loss and it will send a
request for retransmission. However, this will also create an inevitable delay. As a
result, when the video is streaming, a gap will occur such as there is neither sound
nor picture. (Armitage 2000).
Fortunately, in 128 bits of IPv6 are there some new features to increase assured
service, enhance security, and improve reliability. The way of identifying and
handling traffic is defined in new fields of IPv6. By applying a Flow Label field in
the header, it enables packets belonging to a flow are recognized and handled
specially. As the traffic is recognized in the header, QoS can be supported
efficiently. With these enhancements, IPv6 supports applications to request
handling with no delay across the WAN. This will help time-sensitive data to load
with low latency via priority level:
Level 0 - No specify priority
Level 1 - Background traffic (news)
Level 2 - Unattended data transfer (email)
Level 3 - Reserved
Level 4 - Attended bulk transfer (FTP)
Level 5 - Reserved
Level 6 - Interactive traffic (Telnet, Windowing)
Level 7 - Control traffic (routing, network management)
However, although this method minimizes fragmentation and latency, it consumes
more bandwidth for prompt arrival, which results in inefficient utilization (Oracle,
Neighbor Discovery Protocol
FIGURE 10. IPv6 neighbor discovery protocol
Since the invention of IPv6 also comes the new Neighbor Discovery protocol,
which manipulates messaging as the technique to manage the interaction of
neighbor nodes on the same link, which is called Internet Control Message
Protocol for IPv6 (ICMPv6). The list of major activities that the Neighbor
Discovery protocol controls over the IPv6 local link includes router discovery for
supporting hosts to find routers on the local link, address auto configuration for
assigning automatically IPv6 addresses for interfaces, prefix discovery for
discovering the known subnet prefixes to differentiate destinations, address
resolution for determining the link-local address of a neighbor with only the
destinations’ IP address, next-hop determination for applying an algorithm to
identify the IP address of a packet recipient one hop that is beyond the local link,
neighbor unreachability detection for identifying if a neighbor is no longer
reachable, duplicate address detection for determining if an address that the node
wants to use is not already in use, and redirection for supporting routers to inform
a host of a better first-hop node to use to reach a particular destination (RFC4861).
As from those functions above, the Neighbor Discovery protocol for IPv6 is
performing the functions of Address Resolution Protocol (ARP), ICMPv4 Router
Discovery, and ICMPv4 Redirect messages and contributing additional
functionality (Narten, 1999). Neighbor Discovery uses the following ICMP
message types for communication among nodes on a link:
Router solicitation
Router advertisement
Neighbor solicitation
Neighbor advertisement
In IPv6, new features can be extended by adding extension headers after the IPv6
header. Different from the IPv4 header, which leaves only 40 bytes of options, the
size of IPv6 extension headers is only constrained by the size of the IPv6 packet
IPv4 and IPv6 Comparison
32 bits long (4 bytes).
128 bits long (16 bytes).
Consist of a network and a host
Basic architecture is 64 bits
portion, based on address class.
for the network number and
Different address classes are
64 bits for the host number.
constructed: A, B, C, D, or E
The host portion of an IPv6
depending on initial few bits.
address (or part of it) will be
The total number of IPv4
addresses is 4 294 967 296.
The configuration of IPv4 is
derived from a MAC address
or other interface identifier.
The total number of IPv6
addresses is
where 0<=nnn<=255, and each n
is a decimal digit.
The configuration of IPv6 is
For example:
xxx:xxxx:xxxx, where each x
is a hexadecimal digit,
representing 4 bits.
For example:
Not used
Used to assign network from
host portion.
Used by IPv4 to find a physical
No ARP as IPv6 contains
address (MAC or link address),
these functions within itself
associated with an IPv4 address.
for stateless autoconfiguration and neighbor
discovery using ICMPv6.
IP addresses and routes must be
IPv6 interfaces are self-
established while configuring a
configuring using IPv6
new system to communicate
stateless auto-configuration
with other systems.
to communicate with other
IPv6 systems that are local
and remote.
Applications receive host names
Same for IPv6. Support for
( and use DNS to
IPv6 exists using AAAA
get IP address (
(quad A) record type and
Applications also receive IP
reverse lookup (IP-to-name).
addresses and use DNS to get
Applications may elect to
host names.
accept IPv6 addresses from
For IPv4, the domain for reverse
lookups is
DNS (or not) and then use
IPv6 to communicate (or
For IPv6, the domain used
for reverse lookups is or (if not
Used to dynamically obtain an
IP address and other
configuration information.
DHCP does not support IPv6.
on Protocol
Used to send and receive files
across networks.
Does not support IPv6.
Used to communicate network
The same for IPv6 (ICMPv6)
with some new attributes to
support neighbor discovery
and related functions.
IP header
Variable length of 20-60 bytes,
Fixed length of 40 bytes
based on IP options present.
No IP header options.
Simpler than the IPv4 header.
IP header
Many options that might
No options but support some
associate with an IP header
extension headers: hop-by-
(before any transport header).
hop, routing, fragment, and
Used by an IP interface to get to
IPv6 can be used with any
the physical network. Many
Ethernet adapters and is also
types exist; for example, token
supported over virtual
ring, and Ethernet. Sometimes
Ethernet between logical
referred to as the physical
interface, link, or line.
The maximum number of bytes
that a particular link type
on Unit
(Ethernet or modem) supports.
Use a MTU of 1280 bytes.
The layers need to fragment
and defragment the packets
to send over a link with less
than 1280 MTU.
Basic firewall functions in
IPv6 does not require NAT
as the expanded address
space of IPv6 eradicates the
address shortage problem.
Does not support IPv6.
Basic firewall functions in
TCP/IP can be built to forward
IPv6 packets are not
IPv4 packets when they are
transmitting on different
TCP and UDP have separate
The same as IPv4. However,
port spaces in the range from 1
as these are in a new address
to 65535.
family, there are now four
separate port spaces.
Private and
All IPv4 addresses are public,
IPv6 addresses are either
except for three address ranges:
public or temporary.
In class A - 10.*.*.* (10/8)
However, temporary
addresses, which are used to
In class B - to (172.16/12)
shield the identity of a client
when it commences
In class C - 192.168.*.*
communication (for privacy),
can be globally routed.
Private addresses are used within
organizations and cannot be
routed across the Internet.
Temporary addresses have a
limited lifetime and generally
identical to public addresses.
A mapping of a set of IP
The same as IPv4 but IPv6
addresses to a physical interface
routes are associated to a
and a next-hop IP address to
physical interface as because
forward IP packets using the
source address selection
line. IPv4 routes are associated
functions differently for IPv6
with an IPv4 interface.
than for IPv4.
Used to extend a secure and
Does not support IPv6. (IBM
private network over an existing
public network.
Research Data
This section provides data collected in this thesis.
Interviews Data
The questions of our interviews can be found in Appendix 1. Here are some key
responses from interviewees who agreed to participate.
Seppo Syrjanen, Data network specialist from IT Center of University of Helsinki.
“We have 18,000 computers (Windows, Linux, Mac), 50,000 users,
2000 servers. The main purpose for IPv6 deployment project is
testing and preparing for future. There are no problems with IPv6
yet. IPv6 is only used on some test networks and AD Domain
controllers. The method of transition was routing. The transition of
IPv6 is a long gradual process that will take time and efforts. IPv6
of our system is not ready at the moment; it will be a couple of year
until can have an IPv6 address. There is no
external budget for IPv6; it will be done in part of basic
Aleksi Suhonen, Internetworking Consulting – Axu TM Oy
“Our business is involved in a lot of online transaction. The budget
for IP expenditure of our company is 4000 EUR/year. The reasons
for deploying IPv6 are ease of server numbering, future proofing,
and gathering user experiences for consulting purposes. We
expected that IP expenditure would drop once we finally get rid of
IPv4. We applied Dual-Stack and now testing NAT64 on a few
IPv6-only devices. It was tough to get native IPv6 transit at first.
User education must be prepared before the implementation”
Anna Niemi, Traffic Specialist, Oy
“Although we have some deployment of IPv6, unfortunately our
network issues are handled by a company in the Netherlands,
ASP4ALL. We have no intention to deploy IPv6 on our own or at
the moment.”
Nguyen Dac Thuan, Networking Manager of FPT Telecom Corporation.
“We have more than 5000 users and our business is involved in
lots of online transactions. The main reason for deploying IPv6
was testing. We applied Dual-Stack as transition method because
we purchased devices that can run both IPv4 and IPv6 from Cisco
The main problem was to configure software designed for our
system. Other problem was training our staffs about IPv6. Our
IPv6 project got a lot of support from top executives. We will be
very happy to have a complete solution to IPv6 deployment. ”
Nguyen Ho Phi Long, Cisco Certified System Instructor at Nhatnghe Network
Training Center
“Currently, there are around 600 desktops and laptops in the
center with 100 servers, which are all contributed for education.
This means we do many online business and training. The IPv6 is
mainly deployed to cope with the standard requirements from
Cisco Training Program. It was very hard at the beginning but
now everything is running smoothly. As we are a training center,
we use all possible transition methods for educating people. When
we complete IPv6 deployment, we think there will be some
advantages. The main problem was the high cost of IPv6 devices
and the knowledge of our staffs about IPv6. Fortunately, we get
much support from our superiors with a budget of 6000Eur per
year. We are also looking for a solution to deploy IPv6 to the rest
of our network.”
Documents Data
Requests For Comments (RFCs) is a document system invented by Steve Crocken
in 1969 to keep the record as well as improve technology being used on the
ARPAnet. An RFC describes a research or applications on networking
technology or define a new one.
RFCs can be written by anyone who wishes to provide ideas or a new way to
enhance the network. After an RFC is submitted via RFC Editor-page or emails, it
will be evaluated by a group of engineers, which is the Internet Engineering Task
Force (IETF). Engineers and developers of IETF will check then assign a number
to each RFC. Thus, the number is also a unique name for each RFC. For instance,
the first RFC is called RFC 1, and RFC 1 always refers to the first RFC about host
software invented in 1969. Some of RFCs are published as Internet Standards
(STD). Once published, an RFC can never be modified. A modification will be
published as a new RFC with new number. (Blank 2004).
TCP/IP was developed by the RFC method of development. In this thesis, we
consulted RFCs as our data on technical issues. RFCs are the most updated and
trustable papers on networking technology. A set of RFC, which will be used in
this thesis, is stated in Appendix 2 with citations provided by IETF at RFC Index
Page (
Besides RFCs, a set of journal papers on networking technology is also used as
technical data in this study.
IPv4/IPv6 Translation Technology
Nakajima, Masaki, and Nobumasu Kobayashi. "IPv4/IPv6
Translation Technology." FUJITSU sci. Tech. J., 2004: 159-169.
Transitioning from IPv4 to IPv6 - A Technical Overview
Mackay, Michael, and Christopher Edwards. "Transitioning from
IPv4 to IPv6 - A Technical Overview." Lancaster: Computing
Department, Faculty of Applied Sciences, Lancaster University.
Cisco – LISP White Paper Series - Enterprise IPv6 Transition Strategy
Using the Locator/ID Separation Protocol
The development of IPv6 in an IPv4 world as transition strategies
Subramanian, Saisree. IPv6 Transition strategies. November 2003
Network Infrastructure
Developed technologies have created more new functions for the enterprise
networks but they also bring as many risks as well. Therefore, large enterprises
are enhancing computer networks and also adopting new technologies to support a
single network infrastructure which has the ability to provide all the required
services such as higher security, maximum data transmission, scalability, routing
protocols and so on. In addition, this must be achieved with the lowest cost and
efforts to connect business partners, suppliers and employees scattered across
regions. As the requirement for these applications are escalating, it has become
standards for implementing an enterprise communication network to ensure the
provided solutions for real time operation, data transfer speed, and reliability.
Based on the interview with Mr. Seppo Syrjanen, Data network specialist of IT
center, the University of Helsinki is currently in possession of 18000 computers
and 2000 servers with 50000 users located in different areas. As a result, this
network has the needs to meet and support various kinds of request from clients
continuously all day and night. Therefore, it requires a stable, scalable and reliable
network backbone infrastructure to manage online operations effectively, which
normally consists of the following components:
Virtual Local Area Network
FIGURE 11. Virtual Local Area Network (VLAN)
The figure above indicates a model of a VLAN. A large enterprise often is
comprised of many small and medium companies and departments. However, if
each company uses a different network, the communication among departments is
not assured. Therefore, instead of running a different network, each company is
assigned to a unique Virtual Local Area Network (VLAN) and subnet within the
single physical network. Normally, it is a function of routers to create broadcast
domains but with VLAN, a switch can also create the broadcast domain as well.
Furthermore, according to Mr. Nguyen Ho Phi Long, Network Instructor at
Nhatnghe Training Center, VLAN is suitable for large networks with a lot of
broadcast traffic, especially, when the LAN already has more than 200 devices or
more security is required or users run the same application such as VoIP phones.
This helps to ensure the highest level of security and confidentiality for enterprise
Network Address Translation (NAT)
FIGURE 12. Network Address Translation (Odom, Healy and Donohue 2009).
In an enterprise computer network, it is ordinary to conceal an entire IP address
space, comprising of private IP addresses, behind a single IP address or a small
group of IP addresses in another public address space, which is known as Network
Address Translation (NAT). This is the process which aims to alter information in
IP packet headers when being transmitted through a router. Most computer
systems set NAT to work in order to enable multiple hosts on private networks to
access the Internet using a single public IP address. However, NAT is also known
to create enormous disadvantages for the Internet connectivity performance,
which demands careful implementation. For an enterprise network, all clients will
use private addressing internally and external access is achieved using Network
Address Translation (NAT) (RFC3022 2001).
Demilitarized Zone (DMZ)
In large enterprise networks, DMZ acts as an extra layer of security for local area
networks (LANs). In other words, it is a secure zone between the internal
networks (trusted) and the external networks (untrusted). In case the system is
attacked, along with firewall, it will protect the whole internal network. For this
reason, security methods must be added such as stopping unnecessary services,
applying necessary services with minimized privileges, deleting any useless
accounts, and ensuring DMZ to be running with the latest security updates and
patches. This is also called a Data Management Zone which provides secure
services for internal users by servers such as web server contains and delivers
websites of enterprises to customers and suppliers, email server supports SMTP
and POP3 or IMAP to maintain and control the email system within the
organizations, FTP server supports FTP service to transfer files among hosts
within the system, application server contains a software framework providing
environment to support the construction of applications, DHCP server assigns IP
addresses to client computers, which is often used in enterprise networks to reduce
configuration efforts, etc. (RFC2647 1999).
According to Mr. Nguyen Ho Phi Long, Network instructor at Nhatnghe training
center, nearly in every network nowadays, there is always at least one firewall
inside. It can be a system consisting of router, proxy, or gateway to establish
security rules for access control between two networks. In that way, the internal
network is protected against threats from the outside. A firewall can be either a
hardware device or a software program installed on a secure computer. In a large
enterprise network, there are two kinds of firewall implementations: distributed
firewall and centralized firewall.
Virtual Private Network (VPN)
FIGURE 13. Virtual Private Network
Each enterprise has a large number of employees and this will lead to a situation
that when they stay far away from the offices, they also need to access company
data which can only expose to internal networks. For this reason, many large
enterprise networks have arranged to adopt a VPN connection to allow clients
access internal machines securely from the public networks. This acts as a private
network configured inside a public network (Internet) to easily manage facilities
of large networks. Based on the interview with Aleksi Suhonen, Internetworking
consultant at Axu TM Oy, VPNs are widely used by enterprises to create wide
area networks to provide site-to-site connections to branch offices and to allow
mobile users to access their company networks. There are many kinds of VPN
that are being used:
Internet VPNs: Several protocols are used to provide security over the
Internet such as SSL, IPsec, L2TP and PPTP.
Frame Relay VPNs: Carriers offer point-to-point and multipoint VPNs
using frame relay. Customer equipment converts packets to frame relay
Virtual IP VPNs: Carriers offer multipoint networks that accept only IP
packets from the customer and run over an IP core. These virtual private
routed networks (VPRNs) connect the customer's IP router to the
provider's IP router and require some coordination.
Ethernet VPNs from Carriers: Carriers offer services that encapsulate
Ethernet frames and deliver them across their network to an Ethernet
connection on the other end.
Management Issues
In this part, management issues of organizations on deploying IPv6 will be
analyzed. According to responses from the interviews as well as some document
and bloggers of telecommunication, data can be categorized into groups as
following table.
TABLE 8. Management issues
IPv4 exhaustion is obvious and it causes future addressing problems. Our
interviews also revealed IPv4 exhaustion as the most common reason stated. As
we know that IPv4 free pool is out, new Internet connections are rising fast in
developing countries. Once those remaining IPv4 addresses are out, new
connections will be provided with IPv6. If enterprises do not prepare for such
parallel existence of IPv4 and IPv6, they may lose a number of customers who
cannot access them on Internet.
From the interviews with heads of IT departments, the idea that addressing is the
main reason for IPv6 to be created and address space boosting is the only
improvement of IPv6 is pretty popular. In fact, the advances of IPv6 include
update the protocol, addressing space as well as other aspects. Let’s take a look at
some important technical features that IPv6 is designed to archive according to
Mr. Nguyen Ho Phi Long, Cisco Certified System Instructor at Nhatnghe
Network Training Center:
More address space - This feature is the most well-known about IPv6. It provide
up to 2128 = 3.4×1038. It gets rid of NAT, technology for the lack of IPv4. It allows
every device to have a permanent unique public address.
Better Management and Administration - Stateless auto configuration that means
much less manual-configuration of IP address, even with DHC.
Improve routing performance - New header format of IPv6 remove routers from
the fragmentation process, which means more efficient performance from routers.
Better multicasting/Media - IPv6 has built-in features for multicast and unicast
groups. IPv4 had an option for multicasting but the support for it has been
Efficient mobility - As IPv4 was developed at the time when there was no mobile
IP concept which leads to the need of Mobile IP. IPv6 provides mobility support
by eliminating triangular routing.
Better security - IPSec, a framework from IETF, in IPv6 helps to advance the
security implementation. By using IPSec, devices can acquire data privately, data
verification and data integrity at the network layer.
As inferred from the interview with Aleksi Suhonen, Internetworking Consulting
of Axu TM Oy, the most important aspect to an enterprise is cost saving.
Technical features above may not sound very interesting to them. On cost-saving
scale, the transition to IPv6 may offer many benefits for large enterprises. It
promises to bring better routing performance, improve security and autoconfiguration, which generate lower implementation cost, and daily maintenance
basic cost. Therefore, it may save long-term IT cost for enterprises. Here are some
approaches that enterprises that plan to adopt IPv6 should consider.
Firstly, IPv6 should be integrated into the product lifecycle replacement. The
initial step of adopting IPv6 is to examine the existing information system
infrastructure. Some hardware doesn’t support IPv6 while software can be
changed and upgraded. The next step is to specify IPv6 conformity with the RFPs.
Then enterprises can reduce cost of IPv6 transition by including it to the product
procurement plan of the current IT budget. IT staffs may consider the purchase of
IPv6 supporting products while planning their regular procurement plan. In
addition, IPv6 training cost should also be integrated into the IT budget; this cost
may be considerably high during IPv6 adoption. These actions not only aim to
prevent unexpected or unnecessary costs but also make the transition process
According to the interview with Mr. Nguyen Dac Thuan, Networking Manager of
FPT Telecom, a leading telecommunication company in Vietnam, FPT has been
purchasing IPv6 support devices, especially devices of Cisco. The company is
aware clearly of the integration process in order to prepare for future. However,
the training of staffs was not planned well; therefore it cost more than expected.
Transition technologies are also important factors of IPv6 transition process.
There are several common techniques which will be discussed further in chapter 6
of this paper. To lower the cost and the associated operative effect of IPv6
adoption, it can be done by deploying IPv6 components in a fashion starting at the
network bounds and evenly moving “inwards towards the core”. (Das 2008).
Moreover, “the early bird gets the worm”, IPv6 is a certain future that it may bring
opportunities to early service provider. Since many enterprises are new to IPv6,
service provider can be a consultant in decision making while making some profit.
Chip Popoviciu, technical leader with Cisco and co-author of the book Global
IPv6 Strategies, emphasized the value that early adoption can get. Service
providers can sell various services if they can play a role in helping enterprises
deploy IPv6.
IPv6 day, organized in 2010, had indicated the participation of a various
organizations. For some organizations, the reasons for deploying IPv6 include
testing. According to Mr. Seppo Syrjanen, Data Network Specialist from IT
Center of University of Helsinki, universities and especially equipments vendors
who offer hardware and software products would like to make sure they are
capable of communicating between IPv4 networks and IPv6 devices. Demand for
IPv6 devices may be low at present but surely it will rise up in near future. To be
prepared for it, IPv6 support should be integrated into product life cycle soon.
Some organizations deploy IPv6 to test their present system so that it will be
compatible with both IPv4 and IPv6.
IPv6 has been in the game for quite a while, but we have not seen any quick and
eager movement toward the transition from IPv4 to IPv6. What are the reasons for
such hesitations of enterprises?
In the successful IPv6 deployment list of Finnish organizations (derived from, we see companies
like Vertta, who let their service provider do IPv6 deployment for testing. This
company didn’t quite know about IPv6 transition. They left that process for their
service provider.
Ethan Banks, a network engineer and host on Packet Pushers, an independent
podcast on data networking, had shared his view on this issue. He said that his
company does not need IPv6 to do business or reach a new market while there are
no important resources that is only reachable via IPv6 nor customers available
only through IPv6. He also indicated that without a ready service provider along
with transition solution, enterprises seem to be indifferent toward IPv6. (Banks
2011). For that reasons, without excellent service provider in the market,
customers will not be ready to deploy IPv6. There is a saying that “Don't fix it if it
hasn't broken yet”, then why bother changing while the business is going on well.
On the other hand, there is no backwards compatibility in transition to IPv6.
Microsoft has no intention to implement IPv6 for older Window OS such as
Windows 98 or Windows Millennium Edition or Windows 2000 (Microsoft
2008). Therefore, there are some concerns with the cost of replacing a variety of
application, which needs to be IPv6 compatible. However, most of the networking
software support IPv6 comes as an upgrades based on old software version, thus
there is not much extra cost, even no. Nevertheless, specific software tailored for
company is much more different. If an enterprise wishes to transit all software to
IPv6 compatible and eliminate IPv4, it may come up with huge costs. It also costs
a lot of time and efforts of applications developer to change the applications
according to information from the interview with Mr. Nguyen Dac Thuan from
FPT Telecom.
In conclusion, customers’ awareness of IPv6 transition wasn’t so high. Enterprises
currently have not much ideas on what involve in the transition i.e. computers,
network devices, infrastructures. They need a plan before they “hit the IPv6 wall
unexpectedly”. (Middleton 2011).
The transition from IPv4 to IPv6 is not a one-day step and involves a lot of
changes in network structures with the use of IP addresses. For the future success
of IPv6, the next step in deploying IPv6 is to vote for the most suitable transition
methods and their management. Although many kinds of transition mechanisms
have been invented to help with the process, the implementation of IPv6 is never
said to be easy and simple, even for experienced administrators. As a result, the
most difficult problem to make decisions for is which method will be chosen for
the implementation process to achieve a smooth and seamless transition (Raicu
and Zeadally 2003).
FIGURE 14. Different transition technologies (Subramanian 2003)
According to the above picture, there are different kinds of technologies which
can be applied such as dual stack, tunneling mechanisms, and translation
techniques. Over sixteen transition techniques have been used and tested for the
communications between different networks to ensure IPv4 and IPv6
interoperability. Therefore, to make decision on the best suited transition methods,
it is really important to have an overview of the current IPv4 networks. In
addition, enterprises must analyze needed functionalities, scalability, and
securities in the corporation. Besides, “one size does not fit all” and a network can
be applied different transition mechanisms together to support a complete
distributed system.
In this section, based on the information from the research and literature review,
we would present an overview of some major transition methods as well as
relevant matter to opt out the best methods for large enterprise networks. Each
technique possesses individual attributes and plays an important part in the
transition process. In general, we can classify various transition techniques into
three categories with respect to connectivity and necessary elements for the
Method 1 - Dual Stack IPv4/IPv6 Devices
TABLE 9. Dual Stack (Nokia n.d.)
From the table above, the dual stack happens in the network layer, which contains
both IPv4 and IPv6. Stack means, “A stack is a type of data structure -- a means of
storing information in a computer. When a new object is entered in a stack, it is
placed on top of all the previously entered objects. In other words, the stack data
structure is just like a stack of cards, papers, credit card mailings, or any other
real-world objects you can think of. The term "stack" can also be short for a
network protocol stack. In networking, connections between computers are made
through a series of smaller connections. These connections, or layers, act like the
stack data structure, in that they are built and disposed of in the same way”.
(TechTerms n.d.).
However, like any market regulations, the acceptance of any new technology lies
in the way it integrates into the current infrastructure with no serious breakdown
of service. A large enterprise network includes many IPv4 networks and
thousands of IPv4 nodes. Therefore, the transition from IPv4 to IPv6 does not
require upgrades on all nodes at the same time; IPv4 and IPv6 will coexist for
some time. As a result, enterprises can apply dual stack method to transit to IPv6.
The dual stack method is literally to use two IPv4 and IPv6 stacks for operating
simultaneously, which enables devices to run on either protocol, according to
available services, network availability, and administrative policies. This can be
achieved in both end systems and network devices. As a result, IPv4 enabled
programs use IPv4 stack and this goes the same for IPv6. The IP header version
field would play an important role in receiving and sending packets. In other
words, this kind of IPv6 transition is the encapsulation of IPv6 within IPv4. The
complete transition can be managed by DNS, for example, in the circumstance
that a dual-stacked device queries the name of a destination and DNS gives it an
IPv4 address (a DNS A Record), it sends IPv4 packets, or in case DNS responds
with an IPv6 address (a DNS AAAA Record), it sends IPv6 packets. This
mechanism is currently the best choice for the transition as many operating
systems have applied dual IP protocol stacks (Cho, Luckie and Huffaker 2004).
FIGURE 15. The structure of Dual stack model (Oracle Corporation 2001).
As presented in Figure 15, the dual stack method is implemented in the network
layer for both IPv4 and IPv6. Before transferring the packet to the next layer, the
network layer will choose which one to use based on the information from the
datalink layer. Large enterprise networks that are decided to transit to IPv6 can
apply the dual stack method as the basic strategy, which involves the device
configuration to be able to utilize IPv4 and IPv6 at the same time on the core
routers, perimeter routers, firewalls, server-farm routers, and desktop access
routers. Depending on the response to DNS requests, applications can choose
which protocol to use and this choice can be made in consonance with the type of
IP traffic. Furthermore, hosts can attain both available IPv4 content and IPv6
content. Accordingly, dual stack mechanism presents a flexible transition strategy.
However, despite its greatest flexibility, there are still some concerned issues with
this method such as every dual-stack device still requires an IPv4 address; two
routing tables must be maintained in every dual-stacked router; as two stacks must
be run at the same time, additional memory and CPU power will be required;
moreover, every network requires its own routing protocol; supplementary
security concepts and rules must be set within firewalls to be suited to each stack;
a DNS with the ability to resolve both IPv4 and IPv6 addresses is required;
finally, all programs must be able to choose the communication over either IPv4
or IPv6, and separate network management commands are required (Hirorai and
Yoshifuji 2006). For example, based on the figure below, the client computer at
first sends a DNS lookup request for the website Then, the DNS
server will reply with an IPv4 and an IPv6 address of the website. Finally, the
client computer will use that information to send request to the router via either
IPv4 or IPv6 network and the web server will reply the client by allowing to load
the website.
FIGURE 16. IPv4 – IPv6 dual stack operation (Cisco, The ABCs of IP version 6
Method 2 – Translation
FIGURE 17. Translation method model (Microsoft, Technet 2012)
Together with IPv6 deployment strategies into large enterprise networks, the
figure above indicates that there are various translation mechanisms (NAT-PT,
application level gateways (ALG)) also applied to enable the communication
between IPv4-only applications and IPv6-only applications. The meaning of
translation is to convert directly protocols from IPv4 to IPv6 or vice versa, which
might result in transforming those two protocol headers and payload. This
mechanism can be established at layers in protocol stack, consisting of network,
transport, and application layers. The translation method has many mechanisms,
which can be either stateless or stateful. While stateless means that the translator
can perform every conversion separately with no reference to previous packets,
stateful is the vice versa, which maintains some form of state in regard to previous
packets. The translation process can be conducted in either end systems or
network devices (Nakajima and Kobayashi 2004).
The fundamental part of translation mechanism in transition process is the
conversion of IP and ICMP packets. All translation methods, which are used to
establish communication between IPv6-only and IPv4-only hosts, for instance,
NAT-PT or BIS, apply an algorithm known as Stateless IP/ICMP Translator
(SIIT). The function of this algorithm is to translate packet-by-packet the headers
in the IP packet between IPv4 and IPv6, and also addresses in the headers among
IPv4, IPv4-translated or IPv4-mapped IPv6 addresses. However, this does not
mean IPv6 hosts can get an IPv4 address or route packets, but this assumes that
each IPv6 host can have a temporary assigned IPv4 address (Nakajima and
Kobayashi 2004).
Stateless IP/ICMP Translation (SIIT)
FIGURE 18. SIIT Model (Vienna University of Technology 2012)
The above figure indicates an algorithm that designates a two-way translation
between IPv4 and IPv6 packet headers or between ICMPv4 and ICMPv6
messages. The interpretation has been arranged so that UDP and TCP header
checksums are not influenced during the process. More importantly, SIIT is
currently used as the backbone for NAT-PT and BIS (RFC2765 2000).
Network Address Translation-Protocol Translation (NAT-PT)
FIGURE 19. Deployment of IPv6 using NAT-PT (Cisco, The ABCs of IP version
6 2010)
From the figure above, the router is used as a translation communicator between
an IPv4-only network and an IPv6-only network. NAT-PT is considered as a
stateful translator functioning in the network layer with the SIIT algorithm. The
main role of a NAT-PT device, such as routers or servers, is to support numerous
IPv6 nodes by assigning a temporary IPv4 address for each, which permits native
IPv6 hosts and applications to communicate with native IPv4 hosts and
applications. In general, it acts as a communication proxy with IPv4 peers. Proxy
means “a server that stands between an external network (such as Internet) and an
organization's internal (private) networks and serves as a firewall. It prevents
external users from directly accessing the internal information resources, or even
knowing their location. All external requests for information are intercepted by
the proxy server and checked for their validity, and only authorized requests are
passed on to the internal server” (BusinessDictionary n.d.). However, this
mechanism still possesses limitations similar to IPv4 NAT such as point of
failure, decreased performance of an application level gateway (ALG), reduction
in the overall value and utility of the network. NAT-PT also prevents the ability to
implement security at the IP layer (RFC2766 2000).
Bump in the Stack
FIGURE 20. Bump in the Stack model (TechWeb 2009)
The BIS method means there are three more fields inserted into the structure of
layers as indicated in Figure 20. There will be three additional components, name
resolver extension, address mapper, and translator, and are layers between the
application and network layers. The BIS method is specially designed for
communication between IPv4 applications on an IPv4-only host and IPv6-only
hosts. The term bump is used to describe extra modules in a TCP/IP stack. Firstly,
the extension name resolver uses DNS lookups to see if the node supports only
IPv6. Secondly, the address mapper will allocate a temporary IPv4 address for the
IPv6 node and save that in the address mapping caches. Thirdly, the translator
translates packets between IPv4 and IPv6. In the circumstances that a program
needs to transmit data from and to a host, which supports only IPv6, those layers
will play their roles to map an IPv6 address into the IPv4 address of the IPv4 host.
Nevertheless, those temporary IPv4 addresses are only apparent in the end system
and normally come from a private address space. Therefore, BIS is only suitable
to programs that include no address-dependent fields in application layer
protocols. One more thing is that this method can only be implemented on end
systems. The reason for this limitation is that it is easier for translation processes
to solve application to network interoperability problems but it would be harder to
control on a larger scale (RFC2767 2000).
Those are three representatives for the translation mechanism, which are currently
used in the IPv6 transition. With this method, we can easily connect devices in
networks. Furthermore, it requires neither modifications to nodes nor additional
applications to be established on networks. In addition, we only need to make
some adjustments on the boundary routers. However, nothing is perfect and this
translation is also not an exception. Although it has some benefits, the
disadvantages it possesses are also taken into consideration. At first, the first
drawback of the NAT techniques is that the end-to-end security is not supported.
Secondly, due to the function of NAT, routers would become the single point of
failure, which means if anything occurs to routers, the whole networks could
collapse. Finally, the level of complexity in IP addresses would be increased,
which can cause the loss of information in the process (Mackay and Edwards
Method 3 – Tunneling
FIGURE 21. Tunneling transition method (H3C 2003)
The last category for IPv6 transition process is tunneling as presented in Figure
21. This is used to transfer data between compatible networking nodes over
incompatible networks. There are two ordinary scenarios to apply tunneling: the
allowance of end systems to apply offlink transition devices in a distributed
network and the act of enabling edge devices in networks to inter-connect over
incompatible networks. Technically speaking, the tunneling technique utilizes a
protocol whose function is to encapsulate the payload between two nodes or end
systems. This encapsulation is carried out at the tunnel entrance and the payload
will be de-capsulated at the tunnel exit. This process is known as the definition of
tunnel. Therefore, the main issue in deploying tunnel is to configure tunnel
endpoints, determine positions for applying encapsulation. Based on our research,
this mechanism are generally attained via manual or tool-based parameter entry,
existing services like DNS or DHCP, or by taking into use the embedment of
information into IP addresses or applying an IPv6 anycast address. (Bi, Wu and
Leng 2007). Network devices can achieve the two processes of encapsulation and
de-capsulation at tunnel endpoints. In general, tunneling mechanism is a simple
deployment with point-to-point configuration. Nevertheless, tunnels can also be
implemented hierarchically and sequentially. Hierarchical structure is applied in
the circumstances that there are transition tunnels operating alongside with
security or QoS tunnels. Sequential structure can be established in an end-to-end
path, from end systems to local gateways, and beyond. As a result, these two
establishments always increase requirements for processing and packet delay. Up
to date, there exist different tunneling methods such as 6to4, ISATAP, Teredo,
DSTM, and 6over4. Tunnels may be manually configured or automatically
configured. (Qing-weil and Lin 2007).
FIGURE 22. 6over 4 model (Microsoft 2011)
The figure above illustrates the 6over4 method that inserts IPv4 addresses into
IPv6 address link layer identifier part and defines Neighbor Discovery (ND) over
IPv4 by using organization-local multicast. In this method, the multicast enables
IPv4 network to perform as a virtual LAN and the IPv6 target address will be
resolved on this network to get the destination IPv4 address for the tunnel
endpoint. This mechanism accommodates all features of IPv6 such as end-to-end
security, multicast and stateless auto-configuration. It also bears resemblances to
the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) method. (Bouras,
Karaliotas and Ganos 2003).
Dual Stack Transition Mechanism (DSTM)
FIGURE 23. DSTM model (Wedel 2008)
The DSTM mechanism, which is expressed in Figure 23, allows temporary IPv4
addresses to be allocated for end systems with dual stack enabled with connection
to networks that support IPv6 only. The general idea is that IPv4 packets will be
tunneled to pass through IPv6 network to get to the global IPv4 Internet. In the
event that a DSTM end system starts sessions, a DHCPv6 server which has been
modified to acquire a temporary IPv4 address and the address of DSTM border
router, to which packets are later tunneled. On the other hand, in case a node
supporting only IPv4 initiates sessions, the request sent to DNS for the lookup
process would be directed to an adjusted DNS server in the DSTM domain, at
which a temporary IPv4 address will be appointed for the end system. As a result,
incoming packets are tunneled to this IPv4 address (Bouras, Karaliotas and Ganos
6to4 Automatic Tunneling
FIGURE 24. 6to4 Automatic Tunneling model
Automatic means that tunnel configuration is carried out with no additional
management. As shown in Figure 24, this method is considered as the most
popular choice in the field of automatic tunneling technique. When in operation,
this mechanism will have IPv6 traffic tunneled upon IPv4 networks within
isolated 6to4 networks. A special prefix containing the IPv4 address of its 6to4
gateway is supposed to be present in each 6to4 network, which enables tunnel
endpoint addresses are acquired easily and requires no IPv6 administrative work.
Then connection from 6to4 network to the rest of the IPv6 network is established
via a dual stack local gateway and a dual stack relay router. Therefore, every IPv6
packet is directed to the gateway. These kinds of tunnels would transfer the traffic
to appropriate gateway with suitable IPv4 address. (RFC6343 2011).
FIGURE 25. Teredo method (Microsoft 2011)
Teredo mechanism is a technique for assigning addresses and providing tunneling
services automatically to allow IPv6 connectivity across IPv4 Internet. This
method is supposed to be the solution for the lack of 6to4 functionality by
supporting the tunnel for IPv6 packets between hosts within sites while 6to4
method only allows providing tunnels for IPv6 packets between edge devices.
Based on our research, currently networks, which are applying IPv6, face another
problem of NATs. Because of its nature, IPv4- encapsulated IPv6 packets have
the header set to 41, which prevents them to pass through typical NATs.
Accordingly, because UDP messages can be translated universally by NATs and
can traverse multiple layers of NATs, Teredo encapsulates the IPv6 packet as an
IPv4 UDP message, provided that NAT supports UDP port translation, it supports
Teredo. (Huang, Quincy and Lin 2005).
Tunnel Broker
FIGURE 26. Tunnel Broker model (Netnam Ltd. 2011)
This is another approach to IPv6 with the support of dedicated servers, known as
Tunnel Brokers as illustrated in Figure 27, to answer automatically tunnel requests
from users, which is believed to increase IPv6 growth with connected hosts and to
support access to IPv6 networks. Besides, this method makes it easy for IPv6 ISPs
to manage access control by applying own policies on network usage. This is
where users make connection for registering and activating tunnels. Then,
dedicated servers or Tunnel Brokers control the management of tunnels with
activities such as creation, modification and deletion for users. In addition, to
support networks on a larger scale, this method can distribute the workload to
some tunnel servers by delivering orders to concerned tunnel server when there is
a need to manage a tunnel. Finally, connections between tunnel brokers and
servers can occur with IPv4 or IPv6. (Chen, et al. 2002).
Generally, the tunneling mechanism allows us to connect isolated IPv6 nodes and
networks whether or not the ISP has been upgraded to IPv6. Moreover, it also
takes advantage of emerging IPv6 services while remaining connected to the IPv4
world. However, its encapsulation and de-capsulation take more time and CPU
power, and add more complications to troubleshooting and network management
as well. One more thing is that those tunnel endpoints can be single points of
failure and they can be vulnerable to security attacks. (Waddington and Chang
Summary of three methods
Below is the summary table containing the advantages and disadvantages for three
main methods above.
TABLE 10. Summary of three methods
- Configure tunnel endpoints
- Simple deployment
- No additional management
- Face another problem of NATs
- Take more time and CPU power
- Harder to troubleshooting and
network management
- Have single points of failure
- Vulnerable to security attacks
- The router is used as a
- Limitations similar to IPv4 NAT
translation communicator
- Reduction in the overall value
- Solve network interoperability
and utility of the network.
- Harder to control on a larger
- Complexity increases in IP
Dual stack
- Easy to implement
- Two routing tables
- Low cost
- Additional memory and CPU
- Greatest flexibility
- Already supported in all OSs
and devices
- Two firewall sets of policies
Based on the above overview of all mechanisms and current practices in
researched enterprise networks, nearly all deployments of IPv6 in enterprise
networks apply dual stack mechanism as it gives us a way to know more about
IPv6 as well as to improve practical experience with a new address family, which
plays an important role in the success of transition implementation. Therefore, in
this thesis, we choose the dual stack mechanism to build a model for large
enterprise networks.
“Readiness is a state of preparedness of persons, systems, or organizations to
meet a situation and carry out a planned sequence of actions. Readiness is based
on thoroughness of the planning, adequacy and training of the personnel, and
supply and reserve of support services or systems” (BusinessDictionary n.d.).
In expression of IPv6, this means being ready for the implementation of IPv6 into
a network when business requirements arise.
The University of Helsinki, Axu TM Oy, and FPT Telecom Corporation have
already taken initial steps to implement IPv6 into the network system based
answers gathered from the research. Although these efforts are now just meant for
testing, the message from the international community is clear. The transition
from IPv4 to IPv6 will become a must for enterprises, especially ones that
currently provide online services based on IP addresses. They must be able to
handle large requests from internal and external customers who are applying their
emails or web or other services to everyday working lives over the Internet. As a
result, this creates new demands for services to be approachable via both IPv4 and
IPv6, which means organizations, enterprises or even governments who wish to
continue online operations must right now consider the pros and cons of the usage
of IPv6 and analyze future needs to integrate IPv6 into the whole system. It is
impossible to predict exactly when IPv6 will become mandatory for most
companies. However, in accordance with Mr. Seppo Syrjanen, Data Network
Specialist from IT Center of University of Helsinki, although IPv6 adoption is a
need for current companies to prepare for the future, aside from the exhaustion of
IPv4 address for stakeholders to take into consideration, it is not an easy and
single step that can be achieved in a short time but this requires a great amount of
thorough planning and preparation to develop and adjust an IPv6 business case.
Therefore, it is not when IPv4 addresses come to the point of complete
exhaustion, IPv6 has already been considered as purely strategic because this is
not only to establish global connectivity of enterprise networks for the future, but
also to guarantee growth as well.
In this part, based on information from the interviews with large companies and
enterprises, we would like to categorize different preparation activities that can be
applied as a plan in this IPv6 implementation. This part would become a great
asset to assure that a common method is ready to make plans and to check IPv6
readiness when it falls into place for each enterprise network. It is an outline of
phases which have both technical infrastructure and business readiness taken into
account for an enterprise to initiate the transition to IPv6.
Business Side
Phase 1: The determination of business grounds and demands to implement IPv6
An enterprise must have strong and reasonable desires to initiate the IPv6
transition project. They need to realize business requirements, motives and mark
the features of IPv6 to those particular objectives. Five main conditions that need
to be acutely considered are business operations after the depletion of IPv4
addresses, support for a great amount of network devices, enterprise policies for
IPv6 transition, requests from customer, partners, suppliers, and the global-scaled
trade Mr. Nguyen Dac Thuan, Networking Manager of FPT Telecom.
Phase 2: The analysis of profits, expenses, and risks
Enterprises need to assess the impacts of IPv6 transition and which kinds of
benefits it brings to the business. Specifically, they need to perform thorough
analysis to decide which certain line of business or programs can be benefited
from IPv6 transition. In addition, from the interview with Aleksi Suhonen,
Internetworking Consultant at Axu TM Oy, there are other relevant subjects that
also need to be taken into serious consideration such as enhancement of new
services as well as the maintenance of existing services, development of network
efficiency and cost savings (the elimination of NAT or other work-around
methods), the high performance of large enterprise network, simple configuration
of online operations, and the supply of tactical advantages.
Mr. Nguyen Ho Phi Long, Cisco Certified System Instructor at Nhatnghe
Network Traning Center, has said that costs estimation is the most important part
in every project and it can decide the progress of the implementation. Therefore,
once enterprises would like to initiate the IPv6 transition, they also need to be
prepared for the budget that can be used for planning, design (infrastructure
upgrades if needed), implementation testing, deployment, personnel training as
well as operational costs.
Risk in definition is “a probability or threat of a damage, injury, liability, loss, or
other negative occurrence that is caused by external or internal vulnerabilities, and
that may be neutralized through preemptive action” (BusinessDictionary n.d.). In
this IPv6 transition, risk includes business, legal, privacy, security, reliability,
interoperability and technical risks. Only when we can identify risks and the
impact it may affect, will we be able to apply action plans to prevent or reduce the
influence on the whole project. These plans should put emphasis on major
program activities, specific solutions, and impacts.
Phase 3: The settlement of a supervised group (SG) for administration of IPv6
transition project
According to Mr. Nguyen Dac Thuan, Networking Manager of FPT Telecom, the
supervised group will temporarily act as a centralized management office (CMO)
to make plans, administer, and control the progress of IPv6 transition throughout
the entire enterprise. Furthermore, the SG will arrange sufficient resources such as
staffing, training, and budget to support the IPv6 project successfully. This type
of CMO is particularly crucial in large organized enterprises. Specifically, the SG
will be responsible for recruiting suitable members to the group for different roles
and responsibilities; gaining authority rights within the enterprise to support
financial matters for the transition project and set policies to become the priority
in case of shortage of resources; organizing an administration structure to
guarantee the success implementation of IPv6 transition. The SG will be the
leader to set the milestones and targets for the working team and control the
progress through successful results.
Technical Side
Phase 4: The assessment of all assets of current network infrastructure
From the interviews with Head of IT center from Nhatnghe Network Training
Center, the University of Helsinki, we suggest that before starting to implement
the IPv6 transition project, the enterprises need to carry out a complete analysis of
current networks to get an overview of components that may need to be changed
or upgraded to be suitable for transition to IPv6 such as address allocation,
networks services (IP, wireless, VoIP, DNS, DHCP, NTP…), network
management, applications, operational systems and support.
Phase 5: The establishment of architecture for IPv6 project
When implementing the transition from IPv4 to IPv6, there must be an overall
IPv6 architecture for various impacted areas. It should be standard based and
support IPv4 to perform a smooth transition. Moreover, this architecture should
also expect new networks and services as well as foreseeable traffic growth after
the implementation. There are some concerned major areas such as IPv6
addressing plan, IPv6 routing, IPv6 interconnection, IPv6 foreseeable traffic, IPv6
enabled systems, IPv6 deployment plan, transition mechanism (dual stack,
tunneling, and translation), network services, security, management, scalability &
reliability, and service level agreements (RFC2373 1998).
Phase 6: The outline of a specific structure on the influence of IPv6 project
The IPv6 project, once established, will place influence on every platform and
service in the network. As a result, IPv6 capability and its influence will be
decided according to enterprises’ standard for each platform and service, which
consists of commercial and industry standards. This includes the required
resources (devices, personnel, budget, etc.) and the communication between
system integrator and vendor, said by Mr. Nguyen Dac Thuan, Networking
Manager of FPT Telecom.
Phase 7: The development of an IPv6 project plan
In this phase, the SG is required to gather all information and resources to design
a final plan for IPv6 transition in the enterprise network. Because of its
importance, this plan is required to contain a schedule of small projects to be
implemented along with dependencies and priority. Furthermore, in accordance
with Mr. Nguyen Ho Phi Long, Cisco Certified System Instructor at Nhatnghe
Network Training Center, there should be a testing environment for members to
gain experience with new IPv6 features and also to demonstrate the architecture,
plans, policies... One more thing is that the SG should perform trials on the real
enterprise network as well as operational processes to ensure that all devices and
services acquired or developed are IPv6 capable.
Phase 8: The provision of a personnel-training program
This IPv6 transition project involves either business or technical aspects and this
also means the attendance of many users from the board of directors to ordinary
staff to maintain IPv6 readiness. As a result, training is required to update
knowledge and skills for users to familiarize with the new system (RFC4057
2005). However, based on the position of users in the enterprise, there will be
many types of training programs to be suitable for all. Based on the information
from the interview with Mr. Nguyen Dac Thuan, Networking Manager of FPT
Telecom, we divide the training into four categories:
General training program aims to give normal users primary information about
IPv6 and its related issues. This training also includes a summary of IPv6
technologies, a basic knowledge of IPv6 technology, and also business factors or
IPv6 capable services.
Engineer training program is to give detailed information about IPv6
technologies and this is suitable for staff members who are responsible for
analyzing, planning, designing, testing and deploying IPv6.
Operational training program presents specific IPv6 education to employees who
take care of the support for an IPv6 network.
Special training program includes advanced information in certain technology
are, which is suitable for technical specialists or experts in a certain technology
area such as security, mobile, etc.
Stages of Readiness
In this part, based on the information from literature review and interviews, we
have combined that information to create a checking tool for enterprises to assess
IPv6 readiness level in the network. Based on the result from this tool, the board
of directors can have an overview of the current network and make decisions or
plans according to the result. The stages of IPv6 readiness can be arranged into six
ranks, which represent the work to be achieved before implementing IPv6:
Rank 1: The enterprise has no intention to implement IPv6.
At this stage, enterprises have no business requirements and decide not to
integrate IPv6 into the system as they analyze that the expenditure for IPv4
shortage is lower than the effort and budget spent for transition to IPv6 while IPv4
exhaustion will not place influence on their business.
Rank 2: The enterprise has taken IPv6 into consideration but is still unprepared to
initiate it.
At this stage, enterprises may hire IT experts to advise on the IPv6 project or
methods to prevent IPv4 address exhaustion. Moreover, there may be discussions
within the executive group (CIO, CEO, CTO…) to collect information in relation
with IPv6 project such as business and technical requirements as well as cost and
risk for transiting to IPv6.
Rank 3: The enterprise has an IPv6 program in place and is determining important
At this stage, enterprises may establish a business case and a budget for the IPv6
migration. A supervised group is also formed to control and manage the progress
of IPv6 implementation. The members and roles of the IPv6 Transition Group
should be identified. Furthermore, a thorough analysis of current network
infrastructure should be done to check the IPv6 capabilities. There will also be a
deployment and testing plan as well as training programs for staff.
Rank 4: The enterprise possesses an IPv6 project associated by a final plan.
At this stage, enterprises may already have a sponsored IPv6 project which
includes a detailed report of current infrastructure and a tested architecture design
of IPv6 implementation.
Rank 5: The enterprise is in possession of an IPv6 project without any unresolved
crucial issues.
At this stage, enterprises, supported by all detailed documents such as an IPv6
deployment plan, training plan, architecture design, may actively put into practice
those plans and design to perform the first testing on the real networks.
Rank 6: The enterprise has successfully accomplished the IPv6 transition project.
At this stage, enterprises have deployed IPv6 into the system and finished the
testing part. Furthermore, the training programs are also provided for every user.
Last but not least, the system is ready to communicate with other IPv6 networks
from customers, partners, and suppliers.
Below is the table to describe the phases that is suitable for each rank.
TABLE 11. Rank description
Phase Description
The determination of business grounds and
demands to implement IPv6
The analysis of profits, expenses, and risks
The settlement of a supervised group (SG)
for administration of IPv6 transition project
The assessment of all assets of current
network infrastructure
The establishment of an architecture for
IPv6 project
The outline of a specific structure on the
influence of IPv6 project
The development of an IPv6 project plan
The provision of a personnel training
In general, it is necessary for enterprises to thoroughly analyze and implement an
IPv6 transition with clear instructions to serve expectations. However, because of
the specific expectations may change from time to time, and they can be different
by various enterprises, a complete approach with careful planning and preparation
as listed in this part, accompanied by the details for each phase will allow the IPv6
implementation project to be achieved successfully, which will open a new path
for each enterprise to be ready for the next generation of communication
In this part, we will start to implement the IPv6 in the current IPv4 based system.
To support the transition process, we will use a program, Cisco Packet Tracer
(CPT), which is a powerful network simulation software using the core program
from Cisco. Therefore, with the support of CPT, we can create a visual model of a
network by the drag-and-drop methods. CPT is used to simulate network devices
such as switches, routers, and servers... with a virtual IOS for operation and
management. This includes designing network models ranging from simple to
complex level based on practical requirements, simulating IOS platforms for
routers, IPS, PIX firewall, ASA firewall of Cisco, simulating packet-switching
devices such as Ethernet, ATM, Frame Relay switch, etc. (Janitor, Jakab and
Knieward 2010).
In addition to the simulation program, we also build an artifact, a network model
of an enterprise to implement the transition from IPv4 to IPv6. In this model, we
will apply the dual stack mechanism to transit to IPv6.
Enterprise Network Design
Our model has three main areas. At first, the headquarters model (Figure 27), a
center of operations or administration in an enterprise, consists of four groups:
Group 1: The Demilitarized Zone (DMZ) would contain all the most important
servers in an enterprise such as web server, database server, file server, exchange
server… Each of them stores all confidential information, which can only be
accessed by authorized personnel and they will provide information and data for
users inside and outside the network. However, due to the nature of services, these
servers are usually exposed to untrusted networks. Therefore, in the DMZ,
network administrators will apply all the latest patches, technology, and security
to protect the network from hackers and other threats.
Group 2: This group is named “The Instrusion Prevention”, which is the
combination of authentication server, VPN server, and intrusion prevention
servers, responsible for checking logged in users as well as protecting the whole
network from attacks or penetration.
Group 3: Known as “The Service Provision”, this group contains DHCP server,
FTP server, DNS server, etc., providing necessary services throughout the system.
Group 4: Within this “Client Zone” group is the place for all client computers,
laptops, mobile phones, etc., to connect to the network in the enterprise.
FIGURE 27. Headquarter network structure model
Secondly, a branch is a division of the business that can be located in various
geographic areas. Therefore, the network model of each branch is similar to the
headquarter model only without the DMZ.
FIGURE 28. Branch 1 network structure model
Thirdly, the group of ISP routers with VPN users who perform the work outside
the enterprise network still needs to get access to data from protected servers
inside the network.
FIGURE 29. VPN users
And finally, the total enterprise network model is presented in Figure 30 below.
FIGURE 30. The whole network sructure model
Addressing Plan
Although the model includes one headquarters, two branches, and VPN group, in
the scope of the implementation, we only set addressing plans for the
headquarters, edge routers and ISP routers to simulate the network. For the other
two branches, the practice can be applied similarly.
There are two kinds of addresses: static and dynamic. Statically public addresses
are often assigned for main computers, servers, and routers to make it stable so
that other end devices can establish connection to perform various activities such
as accessing data storage, uploading information, downloading file, etc. Dynamic
addresses are distributed for client devices to join the enterprise network.
Therefore, in our network model, we also set the static and public addressing plan
for headquarter as listed below:
Group 1 (DMZ):
Database server
Web server
Mail server
Group 2 (Authentication):
Authentication server
Firewall server
VPN server
Group 3 (Service):
DNS server
DHCPv4 server
FTP server
Group 4 (Client):
DHCPv4 Pool
DHCPv6 Pool –
FEC0:1234::1/48 – FEC0:1234::FFFE/48
Headquarter Router:
Net 2001:ABCD::/32
Net FEC0:1234::/64
Net 2001::/16
Client Zone
Internet Zone
London Router
Net 2001:1234::/32
Internet Zone
Paris Router
Net 2001:D4D5::/32
Internet Zone
Implementation Peformance
Dynamic Host Configuration Protocol (DHCP)
DHCP is used to assign IP addresses automatically for end devices, such as
laptops, desktops, and mobile phones when joining the network. In our model, as
we apply the dual stack method, there would be one DHCPv4 for IPv4
distribution and one DHCPv6 for IPv6 assignment. Therefore, there will be a
server in the “Service Provision” group to provide IPv4 for all devices in the
“Client Zone” group and it will be configured as in Appendix2. For the IPv6,
although IPv6 resource is very large, we will apply the IPv6 unicast site-local
address for the local clients to ensure security and better management. However,
due to the limitation of the simulator program, the edge router will act as the
DHCPv6 for the distribution of IPv6 to client devices and the configuration can be
found in Appendix 3.
Open Shortest Path First (OSPF)
There are different distinct networks within a large system such as network for
servers, network for clients, and network for security. As a result, a routing
protocol is required to connect these networks together so that a user from client
network can communicate with servers to get access to private information.
Among many routing protocols, we choose the OSPF, which known as a routing
protocol for IP that operates mainly as a link-state protocol and it is very suitable
for large enterprise networks because of its capability and interoperability. As in
the enterprise network model, according to the dual stack transition, we would
create and maintain two routing tables for IPv4 and IPv6 as in Appendix 3.
Border Gateway Protocol (BGP)
In order to build our model, we need to set up the Internet to enable the
communications between the headquarters and branches. Therefore, we apply the
BGP routing protocol, which is mainly used for core routers among autonomous
system around the world. Most ISPs use this protocol to communicate with each
other. The configuration of BGP for the simulation of Internet can be found in
Appendix 3.
Virtual Private Network (VPN)
VPN is a private network that is used by nearly almost every large company to
make it convenient for mobile employees but still ensure data safety via the
Internet. As a result, we also simulate this group of users in our network model
according to the Appendix 3.
Security Establishment
The most important matter in large networks is security, especially with the new
IPv6 implementation. The security is achieved during the implementation process
in the infrastructure to protect the system safe when using both IPv4 and IPv6.
These acts can include setting usernames and passwords, applying network
policies, encrypting data when sent and received, creating access list for better
control and management. See Appendix 3 for more detail.
This part presents the whole thesis structure for better understanding of the study.
Chapter 1 introduced the topic of this study that was the method of transition from
IPv4 to IPv6 that is best for large network enterprises.
Chapter 2 presented the research question, research objectives and research
methods. The main purpose of this study was to find out the most practical
transition method for enterprises with large network. This research question type
is “solution” which requires a problem solving process. Therefore, design science
method was applied. Hence, 7 guidelines of design science were followed strictly.
Chapter 3 concerned data collection method and data analysis. Since qualitative
approach was used, qualitative data collection methods such as interviews with
open-ended questions and document review were conducted. Content analysis was
chosen as data analysis method since we analyzed a lot of technical papers on
current transition methods. We need direct understanding of these papers as to
what they said, what they instructed. Content analysis helped us to understand
what is the nature of the text itself. It also helps with analyzing interview
Chapter 4 was the literature review of IP, IPv4 and IPv6. The basic concept of IPs
and their features were presented thoroughly in this chapter.
Chapter 5 analyzed data that had been collected via documents and interviews.
Data were categorized into groups based on technical or managerial content. This
chapter discussed network infrastructure of large enterprise networks and
management issues on transition from IPv4 to IPv6.
Chapter 6 evaluated the three most current applicable methods of transition that
were dual stack, translation and tunneling. These methods were evaluated
according to data analyzed in chapter 5 to conclude the most suitable method that
was dual stack.
Chapter 7 suggested several matters to consider when deploying IPv6 on both
management scale and technical scale to make it efficient and profitable.
In chapter 8, an artifact was built to test the method. A model of an enterprise
large network would be built in a virtual environment via simulation software.
The chosen method was tested. This chapter contained detailed technical steps on
how to apply dual stack method.
Research result
The first objective was to understand current IPv6 transition methods based on
knowledge about IP in general as well as IPv4 and IPv6 in particular. The authors
learned that global IPv4 free pool was completely exhausted now; the transition to
IPv6 would be a must for near future. There are three transition methods that were
most applied i.e. dual stack, translation and tunneling. Each of them has its own
advantages and disadvantages.
The second objective was to analyze real life experiences of enterprises that had
deployed IPv6. We learned that the reasons for starting IPv6 could be:
Preparing for IPv4 shortage coming in near future
Testing the transition process
Better features
Getting support from top executives on the project
On the other hand, some enterprises were not interested in IPv6 transition for the
following reasons:
Business is still going on well
Training costs
No instant advantages
No solution from service providers
No backward compatibilities
For those above reasons, dual stack seems to be the best method. It is flexible
because it utilizes both IPv4 and IPv6 at the same time on routers and easy to
handle. Translation method makes the network vulnerable, as the whole networks
will collapse if something bad happens to the routers in the transition process.
Tunneling adds more complications to network management and has troubles with
security attacks, which will not make executives happy.
Understand the situation. Most companies are running well with IPv4. Although
global free pool of IPv4 is exhausted, regional ISP still has a certain amount of
IPv4 to provide. They won’t have troubles until several years. What will come
then? Developing countries with increasing numbers of new computers and
devices connecting to the Internet will need their IPs, which will be IPv6. These
countries are new markets which large international companies are aiming at.
Being slow to adopt new technology will lead to losing access to these potential
customers. Besides, IPv6 has new features that promise to bring better
management and administration as well as improve security. Moreover, service
providers who can offer enterprises services in transition obviously can make
profit out of it.
Be prepared. In every project, the most vital part is to plan the implementation
process. Proper budget must be considered in advance including planning, design,
testing, deployment, personnel training and operational costs. Assessment of
current network structure to outline architecture for an IPv6 project is important.
Once the project is decided, IPv6 must be integrated into IT procurement. Even if
it is decided not to deploy IPv6, still IPv6 support products should be integrated
into product lifecycle replacement. The reason is that the network will still be able
to communicate with IPv6 from the outside world and it makes the transition
process much more fluent in case the organization needs to deploy IPv6 later on.
Software or a system tailored for specific organization should be considered an
IPv6 matter, as it is very difficult to change in the future. “Prior preparation
prevents poor performance” (James Baker).
Pay attention to human factor. The human factor includes staffs of project teams
and the operational administrator. Project team members must be people who
really understand internal network structure because they will decide which
method of transition to apply. Choosing the right method will avoid many troubles
for administration. The operational administrator must be the one who has
knowledge of IPv6. As mentioned before, in the case of FPT Telecom in Vietnam,
after IPv6 deployment, the administrator didn’t really know IPv6, which increased
the cost of staff training and decreased effectiveness of the project.
The thesis followed seven guidelines of design science method. It was an
inductive study looking for a solution to a problem. The interviews in this study
were conducted with people who are involved in IPv6 deployment projects in
large network enterprises in Vietnam and Finland. Therefore, they can answer the
questionnaire with their practical experiences.
Additionally, document review was essential for this study since this thesis
concerned a lot of technical issues and evaluated situations based on existing
techniques, which were documented in various published sources. It was
important to study documents on technical experiences of previous projects as
well as new technology coming.
Content analysis was the right choice for analyzing those documents and
interviews’ transcripts.
Limitation and Further Study
The first limitation of this study is that, there were only 4 large network
enterprises interviewed. The authors tried to contact as many large enterprises in
Finland and Vietnam who had deployed IPv6 as possible. Unfortunately, very few
answered back and helped. Half of enterprises that answered back had
successfully carried out IPv6 project while the other half had failed. Therefore, the
authors could analyze reasons for the success as well as failure to find out the best
This study was limited to large enterprises that had a network size of over 1000
computers. Consequently, the research results may not be true for smaller
Finally, there are various areas for further study based on this thesis. Firstly, a
study with a larger sample or more cases could be done for better results. Another
topic could be transition method for small and medium network enterprises. Or it
is possible to find the critical factors for the failure of IPv6 deployment in general
or large network size enterprises in particular (or small and medium sized ones).
Additionally, further study on IPv6 for mobile devices can be considered.
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APPENDIX 1: Questionnaire
1. Does your business involve in online operations (transaction, marketing,
recruitment, communication)?
2. How much is the total IT expenditure in particular account (in percent) of your
organization’s total expenditure?
3. How large is your current computer network? (Number of
4. What are the main reasons for deploying IPv6 in the organization’s network?
5. What is the expected budget that your organization would be willing to spend
for the transmission from IPv4 to IPv6?
6. Which factors that initiated the IPv6 project?
7. What was the method of transmission chosen to be applied?
8. Are there any problems during the implementation? If possible, could you tell
what they are?
9. Which factors needed to be prepared for the implementation?
10. If the implementation of IPv6 was successful, what is the most important
factor? Are there any advantages that the organization gets after deploying
11. If the implementation was failed, could you tell what the main reasons were?
Will your organization consider re-implementing IPv6?
12. Would you consider deploying IPv6 if there is a complete solution? What do
you expect from this solution?
APPENDIX 2: List of RFCs used in this thesis
RFC 2373
IP Version 6 Addressing Architecture. R. Hinden, S. Deering. July
1998. (Format: TXT=52526 bytes) (Obsoletes RFC1884)
(Obsoleted by RFC3513) (Status: PROPOSED STANDARD)
Benchmarking Terminology for Firewall Performance. D.
August 1999. (Format: TXT=45374 bytes) (Status:
Stateless IP/ICMP Translation Algorithm (SIIT). E. Nordmark.
February 2000. (Format: TXT=59465 bytes) (Obsoleted by
Network Address Translation - Protocol Translation (NAT-PT).
G. Tsirtsis, P. Srisuresh. February 2000. (Format: TXT=49836
bytes) (Obsoleted by RFC4966) (Updated by RFC3152) (Status:
Dual Stack Hosts using the "Bump-In-the-Stack" Technique
(BIS). K. Tsuchiya, H. Higuchi, Y. Atarashi. February 2000.
(Format: TXT=26402 bytes) (Status: INFORMATIONAL)
Traditional IP Network Address Translator (Traditional NAT). P.
Srisuresh, K. Egevang. January 2001. (Format: TXT=37675
bytes)(Obsoletes RFC1631) (Status: INFORMATIONAL)
IPv6 Enterprise Network Scenarios. J. Bound, Ed.. June 2005.
(Format: TXT=33454 bytes) (Status: INFORMATIONAL)
Neighbor Discovery for IP version 6 (IPv6). T. Narten, E.
Nordmark, W. Simpson, H. Soliman. September 2007. (Format:
TXT=235106 bytes) (Obsoletes RFC2461) (Updated by
Special Use IPv4 Addresses. M. Cotton, L. Vegoda. January 2010.
(Format: TXT=20369 bytes) (Obsoletes RFC3330) (Also
Advisory Guidelines for 6to4 Deployment. B. Carpenter. August
2011. (Format: TXT=51496 bytes) (Status: INFORMATIONAL)
Internet Protocol. J. Postel. September 1981. (Format:
TXT=97779 bytes) (Obsoletes RFC0760) (Updated by RFC1349)
(Also STD0005)(Status: STANDARD)
APPENDIX 3: Detail steps to configure network according to model built in
chapeter 8
OSPFv2 for IPv4
Goal: Establishing OSPFv2 routing protocol for IPv4
Detail steps:
OSPFv2 verification:
Unit testing:
o Ping from client computer to database server
FIGURE 31. Ping from client computer to database server
o Ping from DHCP server to client laptop
FIGURE 32. Ping from DHCP server to client laptop
From those results above, we have successfully implemented the OSPFv2 routing
protocol for IPv4 to establish the internal communication among clients and
OSPFv3 for IPv6
Goal: Establishing OSPFv2 routing protocol for IPv4
Detail steps:
OSPFv3 verification:
Unit testing:
o Ping from client computer to database server with IPv6
FIGURE 33. Ping from client compurter to database server with Ipv6
o Ping from client computer to database server with IPv6
FIGURE 34. Ping from client computer to database server with IPv6
Based on the test results and the routing table in the verification part, we have
achieved the goal of establishing OSPFv3 for IPv6 on each interface.
In the DHCP server, we configure address pool as depicted in the below picture:
FIGURE 35. DHCPv4 Configuration
Goal: Configuring IPv6 address pool
Detail steps:
DHCPv6 Verification:
Based on the results in verification step, we have successfully set up the IPv6
address pool ranging from FEC0:1234::1/48 – FEC0:1234::FFFE/48 through the
interface fast Ethernet 0/0 with the IPv6 address FEC0:1234::2/64.
Border Gateway Protocol (BGP)
Goal: Establish BGP routing protocols for 4 ISP routers to simulate the
Detail steps to establish BGP
o ISP1’s router:
o ISP2’s router:
o ISP3’s router:
o ISP4’s router:
Unit testing:
o Ping from PC on ISP3’s router to Web server in Headquarter
FIGURE 36. Ping from PC on ISP3’s router to Web server in Headquarter
Virtual Private Network (VPN)
Goal: Establish VPN for remote users
Detail steps:
o Headquarter Router:
Unit testing:
o Ping from VPN laptop to Database server in headquarter
FIGURE 37. Ping from VPN laptop to Database server in headquarter
Goal: - Set passwords for routers on all opening lines such as console,
telnet, and auxiliary.
- Configure encryption with IPSec
- Set IPv4 and IPv6 access list for traffic filtering.
Detail steps:
o Set password for privileged mode
o Set password for console line mode
o Set vty password for telnet line
o Set password for auxiliary line mode
o Configure encryption with IPSec
o Set IPv4 extended access list to prevent ICMP (DOS attack) from
the internet
o Set IPv6 access list to prevent ICMP (DOS attack) from the
Security verification:
o Show IPSec
FIGURE 38. Show IPSec
o Ping from PC of ISP3’s router to Mail server using IPv4
FIGURE 39. Ping from PC of ISP3’s router to Mail server using IPv4
o Ping from PC of ISP2’s router to Database server using IPv6
FIGURE 40. Ping from PC of ISP2’s router to Database server using IPv6
The final completed network model
Figure 41 is the pre-configured model of the whole network. As we can see all the
FIGURE 41. Pre-configured model
red dots means the routers have not been established correctly.
FIGURE 42. Configured model
Figure 42 is the configured and final model of the whole network. Based on the
green dots, the model has been configured and ready to be used.
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