1. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
INTERNATIONAL JOURNAL OF ELECTRONICS AND
6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME
COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 4, Issue 5, September – October, 2013, pp. 169-176
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IJECET
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TRANSITION FROM IPV4 TO IPV6
Chirag Mulchandani, Kinjal Mistry, Purva Chawan, Abhishek Shetty
Electronics and Telecommunication Engineering,
D. J. Sanghvi College of Engineering
ABSTRACT
Currently IPv4 is facing the problem of address exhaustion and it has become a necessity to
make a transition to IPv6. However, the deployment of IPv6 has been happening at a slow rate even
after it promises to provide enhancements to IPv4. The main aim of this paper is to present
information about the transition process from IPv4 to IPv6. Initially, the paper states the prominent
features of IPv4 and IPv6 and also mentions the limitations of IPv4 which created a platform for the
need of transition to IPv6. It also discusses the advantages of IPv6. Finally, it explains the transition
mechanisms specified by Internet Engineering Task Force (IETF) along with their advantages and
disadvantages.
Keywords: IPv4, IPv6, IP sec, routing infrastructure, dual stack mechanism, tunnelling mechanism,
translational mechanism, protocol translation (PT)
INTRODUCTION
Internet plays a very big role in the lives of individuals by making information available in a
quick and easy manner. Internet has revolutionized the world of communication. It has
fundamentally changed lives of individuals and business operators in the developed world. With this
huge growth in the internet, there is an increased demand for better, faster and efficient technology.
This has increased the demand for addresses required for sending and receiving information.
Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP) which
was developed by the Internet Engineering Task Force (IETF). It was mainly developed to deal with
the problem of address exhaustion faced by IPV4. With the increase in the use of Internet-based
resources globally and the shift of circuit switched technologies to IP based technologies in various
Communication Networks, the problem of address exhaustion in IP4 is getting worse.
The current version of Internet Protocol (IPv4) has not substantially changed in the past 20
years. In this span of time, IPv4 has witnessed robustness, easy implementation, interoperability and
accommodation of rapidly growing internet. However, the continued expeditious growth of the
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
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6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME
Internet enabled devices and the em
emerging necessity for secure transfer of data over the Internet are
surpassing the capabilities of IPv4 and are setting limitations.
INTERNET PROTOCOL VERSION 4(IPv4)
4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one
of the core protocols of inter-networking methods of the Internet, and most traffic is routed by it.
networking
Being a connectionless protocol, IPv4 is used on packet-switched networks. It does not guarantee
packet delivery, or proper sequencing of data. These aspects are addressed by an up
upper layer, such as
Transmission Control Protocol.
The following are some important features of IPv4:
Addressing: IPv4 addresses are made up of 32 bits, which allows a total of 4294967296 (2^32)
addresses. This number was not enough and as users were assigned addresses, it gave rise to IPv4
assigned
address exhaustion. In IPv4, special address blocks are reserved for multicast addresses (~270
million addresses) and private networks (~18 million addresses).
Packet Header: Ipv4 has a 32-bit packet header which contains 20 bytes of information. The header
bit
has variable length which depends on whether the Options field is used or not. An IP packet
comprises of two sections: Header and Data. The IPv4 packet header comprises of 14 fields. Out of
these, 13 are required. The 14th field named 'Options' is optional. In the packet header, the most
4th
significant byte is packed first. In the table below, this byte is the version field.
Figure1: IPv4 Packet Header
Packet size: The maximum packet size is 65535 octets. There is a compromise between overheads
There
of small packets and line seizure by large packets.
Address Allocation: Address allocation is done using network classes: A, B and C. Local use of
address is limited to the link. There is no room for expansion due to exhaustion of current addresses.
Address notation: Ipv4 addresses which are 32-bit integers values can be expressed in any notation,
32
but for human convenience, they are often written in dot-decimal, which has four octets expressed in
dot decimal,
decimal and separated by periods.
Address Types:
Different types of addresses are:
1.) Point to point address
2.) Local broadcast and limited multicast
3.) Experimental any cast (not widely available)
Fragmentation: The routers perform multiple step fragmentation of packets for the sake of the
receiver, but this affects router performance.
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3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
Engineering
6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME
Security: Security in IPv4 is limited as no authentication or encryption is done at IP level. This
makes it more dependent on higher level protocols, making it more vulnerable to address de
deception
and denial of service attacks.
INTERNET PROTOCOL VERSION 6 (IPv6)
Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP). It
was developed by the IETF as a solution to the problem of address exhaustion in IPv4.
IPv
For a device to communicate with other devices using the internet, it must be assigned an IP address.
As the number of devices on the Internet increased, the need for more addresses than existent ones
arose.
Addressing: IPv6 has a 128-bit address, which accommodates 2^128 or around 3.4×10^38 addresses.
Packet Header: Packet header in IPv6 is of fixed size: 40 octets. This increases efficiency of the
network.
A packet in IPv6 has the following parts: a header and a payload.
The header comprises of a fixed part with minimal functionality that packets require and may be
extended for special features.
Figure 2: IPv6 Packet Header
Packet Size: As in IPv4, normal packets having up to 65536(2^16-1) octets are handled. However,
65536(2^16 1)
However
the concept of jumbo grams is introduced in IPv6, which are packets with up to
4294967295 (2^32−1) octets. These can also be handled. This improves performance over a high
−1)
highMTU link.
Address Allocation: In IPv6, address allocation is hierarchical by provider, registry, subscriber,
subnet and geographical region. Link as well as site is allowed the local use of address.
Approximately 70% of the total addresses are reserved for use in future.
Address notation: IPv6 addresses are expressed in the hexadecimal form. It consists of eight groups
consists
of four digits each, separated by colons. Since this is a long and inconvenient way, there exist
methods of shorter notation.
Address Types:
The following are the types of addresses in IPv6:
IPv6
1.) Multicast – many interfaces can be sent data at once
2.) Anycast – one of the several groups of interfaces is sent data
Fragmentation: Here, fragmentation is done by the host and not router. It can be done not more than
once. The host checks MTU over the link before performing fragmentation. The router performance
is thus improved.
Security: IPv6 conducts authentication as well as encryption. In addition to this, security
associations are administered to handle key distribution.
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SHORTCOMINGS OF IPv4
With IPv4 being the most widely deployed Internet protocol that is used to connect devices
on the internet, it still has some drawbacks. Some of which are stated below:
I.) Exhaustion of IPv4 addresses: With the advancement of the Internet, there is a considerable
increase in for Internet addresses, in turn draining the supply of IPv4 addresses. IPv4 has32 bit
capacity and hence some organizations are forced to use NAT (Network Address Translation) in
order to map multiple private addresses into a single public IP address. The primary reason for
exhaustion of IPv4 addresses is inadequate design capacity of the initial Internet infrastructure.
However, additional driving factors have worsened the shortcomings. Increased Internet deployment,
new and advanced devices for network, etc are few factors that have raised the demands for IPv4
addresses. The exhaustion of IPv4 addresses can have various effects in different parts of the world.
The effects can trigger the change rapidly in developing economies.
II.) Complexity of configuration: Present IPv4 must be manually configured. Implementation can
also be done using a state full address configuration protocol like Dynamic Host Configuration
Protocol. As more computers and devices use IP, there is a requirement for an easier and higher
automatic configuration of addresses that are independent of the administration of a DHCP
infrastructure.
III.) Flat Routing Infrastructure: In the initial internet, for creating a hierarchical routing
infrastructure, address prefixes were not assigned. Rather, individual access prefixes were allocated.
Each address prefix became a new route in the routing tables. As a result, Internet backbone routers
are required to maintain irrationally large number of routing tables. The large routing tables have
over 85,000 specified routes. Current IPv4 infrastructure has both, flat and hierarchical routing.
IV.) Security: Internet supports private communication over a public medium. Hence, security calls
for encryption services that should protect the data that is being sent from being viewed or being
modified in the transmission. The rapidly increasing hostile environment on the internet demands
built in security.
V.) Quality of Service (QoS): Presently, Internet users not only limit themselves to web browsing
and searching data but also are well acquainted with the text, voice and video chat features and
online video libraries and video conferences. This type of communication requires real time data
transfer service. These services require TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). Real-time traffic support depends on the IPv4 Type of Service (ToS) field but it has
limited functionality. When the IPv4 packet payload is encrypted, Payload identification using a
UDP Port is not possible.
ADVANTAGES OF IPv6
I.) Large Addressing Space: IPv6 has 128 bit long addresses. Hence, an address space with 3.4 x
1038 addresses is possible. This number of address space is abundant for the anticipated future. It also
allows all kinds of devices to connect to the internet not making the use of Network Address
Translators (NAT’s) and hence allowing spotless transparent end-to-end security. Address space can
be also be assigned internationally.
II.) Flexible Addressing Configuration: There are plenty of possibilities for address representation
that have structures like multicast, anycast, unicast, etc. The anycast structure is an identifier to a set
of interfaces having different nodes. When a packet is sent to an anycast group, it will be delivered to
the nearest interface (one of the group members) and hence limiting data flooding
The multicast structure is also a set of interfaces, but, unlike anycast, when a packet is sent to the
anycast group, it will be delivered to all the addresses given by that address). Hence, there is
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transmission of a single data packet to multiple receivers. Multimedia applications can take
advantage of multicast
III.) Hierarchical routing infrastructure: Global addresses are designed to be hierarchical that
leads to relatively few routing entries of the routing tables of the Internet backbone routers. Faster
routing is possible due to the efficient routing table organized with hierarchical routing infrastructure.
Hierarchical routing is measurable enough to sustain the growth of internet due to the large address
space.
IV.) Automatic Configuration: IPv6 supports two configurations, the state full address
configuration (with DHCP) and stateless address configuration (without DHCP automatic
configuration). Hence, IPv6 hosts can configure themselves automatically in the absence of an
address configuration infrastructure using stateless address configuration.
V.) Improved Security: IPv6 requires support for IPsec. IPsec is a framework of open standards
developed by the Internet Engineering Task Force and functions at a low-level in the layers between
the physical wire and a software application. Support for IP sec promotes interoperability between
different IPv6 implementations. It also provides standard based solutions for network security
demands.
THE PROGRESSION FROM IPv4 TO IPv6
The main criteria for smooth transition from IPv4 to IPv6 is compatibility between the two
protocols as majority of hosts and routers currently use IPv4 and it is not feasible to make a complete
switch in a short span of time. Also Network protocol transitions require significant investment and
work, and with the exhaustion of IPv4 addresses mounting, there is lack of time to complete the full
IPv6 transition.
The techniques through which IPv6 hosts and routers can interoperate with IPv4 hosts and
employ the existing IPv4 routing infrastructure are discussed below.
I.) Dual Stack Mechanism: Dual Stack refers to TCP/IP capable network equipment that provides
support for both IPv4 and IPv6. It means that if the end user isIPv6 ready then IPv6 is used and if
the end user is IPv4 ready then IPv4 is used. Both IPv4 and IPv6 protocol stack is run by hosts and
routers as specified in IETF RFC2893.Thus, with all new devices to be both IPv6 and IPv4 capable
allows these devices to have the capability to use either of the IP versions, depending on the
availability of the network, service, and the administrative policy. This means that, for each datagram
the router has two routing tables and two routes will be calculated but only one of them will be
followed by the packet. The application needs to know that routers have a double stack. Figure3
shows the dual stack mechanism in which IPv4 networks communicate with IPv6 networks.
Figure3: Dual Stack Mechanism
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Advantages
1.)
Easy to understand and implement.
2.)
It is the most direct method for a smooth transition from IPv4 to IPv6.
Disadvantages
1.)
Decreases the performance of devices.
2.)
Network complexity and cost increased.
Allows communication only between similar network nodes i.e. IPv6-IPv6 or IPv4-IPv4.
3.)
II.) Tunnelling Mechanism: The term “tunnelling” in general refers to a method of enveloping one
version of IP in another so the packets can be sent over a network that does not support the
enveloped IP version. In other words, tunnelling is used to implement the interconnection between
the isolated IPv4 networks distributed in an IPv6 network or the isolated IPv6 islands distributed in
an IPv4 network. For example, when two IPv6 islands need to communicate over an IPv4 network,
dual stack routers at the network borders can be used to set up a tunnel which envelopes the IPv6
packets within IPv4 thereby allowing the IPv6 networks to communicate without having to modify
the IPv4 network infrastructure. Thus, tunnelling facilitates internetworking between IPv6 islands
without the up gradation of the entire IPv4 network. The tunnelling mechanism is shown in figure4.
Figure4: Tunnelling of IPv6 over IPv4 network
Types of tunnels:
A.) Configured: In configured tunnels, the network administrators manually configure the tunnel
within the endpoint routers at each end.
B.) Automatic: In automatic tunnels, the devices create their own tunnels to end point routers for
shipping IPv6 packets within IPv4
Advantages:
1.)
Easy to implement over existing IP4 network.
Best technique for older legacy equipment.
2.)
3.)
Easy to use at the early stage of transition.
Disadvantages:
1.)
Breakdown of tunnel will fail the network.
2.)
Creation of tunnel can be costly.
III.) Translational Mechanism: As the name suggests, this technique translates the IP packets i.e.
from IPv4 to IPv6 and vice versa. Translation devices are located on the edges of two networks.
They translate corresponding fields of the IP header and the IP address carried in the packet body.
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Network Address Translation (NAT): The NAT mechanism is an IPv4 to IPv6 translator.
Nodes of NAT-PT are at the boundaries between IPv6 and IPv4. When sessions are initiated between
IPv4 and IPv6, each NAT-PT node maintains a pool of IPv4 addresses which are globally routable
and they are dynamically assigned to IPv6. This mechanism allows native IPv6 hosts and routers to
communicate with native IPv4 network devices and vice versa. NAT-PT uses an Application Layer
Gateway (ALG) functionality that translates Domain Name System (DNS) mappings between
protocols. The translation from IPv4 to IPv6 using NAT-PT router is shown in figure5.
Figure5: NAT-PT Translation Mechanism
Advantages:
1.)
Provides a smooth migration to IPv6 and provides seamless Internet experience to Ipv6 users
only.
IPv4 Network infrastructure need not be changed substantially to provide services to IPv6
2.)
networks.
3.)
Cost is low.
Disadvantages:
1.)
Tie up with ALG functionality causes hindrances to deployment of NAT-PT.
2.)
Not supported on end-to-end basis.
3.)
Single point of failure.
PROBLEMS IN IMPLEMENTING IPv6
Deployment of IPv6 is a big challenge for service providers and stake holders. IPv6 is highly
incompatible with IPv4 for deployment at the packet level. Translation services have various
practical issues that make it disputed. As a result, IPv4 and IPv6 are treated as completely separate
networks with hosts and routers having two separate protocol stacks in case devices need to access
both networks. Another challenge is the upgrade jump from 32 bit of IPv4 to 128 bit of IPv6. The
implementation of IPv6 is as good as planning to implement a new technology that includes
increased project risks. Planning to deploy IPv6 must also take into account the lack of broad
experience with protocol. Due to the large size of the IPv6 addressing space, reverse name mapping
which is an essential part of daily administrations over the internet is impossible to carry out
manually. Hence, it is clear that the complexities in the implementation of IPv6 will require judicious
use of time in the transition period from IPv4 to IPv6.
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CONCLUSION
While IPv4 has had an overwhelming durability in the ever increasing networking world,
major limitations like the exhaustion of addressing space coupled with other basic limitations makes
it essential to implement features of IPv6. With the increased addressing space made possible in the
IPv6 addressing scheme, the solution is deploying IPv6. As the number of Internet-based devices
continues to increase worldwide at an exponential rate, the increased availability of the internet in
remote areas and the use of Internet enabled devices in population dense areas, the need for the
flexibility extended by IPv6 will be very important. However, transition from IPv4 to IPv6 at an
instant is not possible due to the large number of IPv4 users. Taking into account the risks of this
immigration a serious challenge is presented to the technologists, which when accomplished
successfully should defeat the difficulties.
REFERENCES
[1]. IPv6: Theory, Protocol, and Practice, 2nd Edition(The Morgan Kaufmann Series in
Networking)
[2]. IPv6 essentials- Sylvia Hagen.
[3]. RFC 2462: IPv6 Stateless Address Auto configuration
[4]. http://pic.dhe.ibm.com/infocenter/iseries/v6r1m0/index.jsp?topic=/rzai2/rzai2compipv4ipv6.htm
[5]. www.cisco.com
[6]. IPv4/IPv6 Transition Mechanisms--European Journal of Scientific Research
[7]. RFC 1933- Transition Mechanisms for IPv6 hosts and routers
[8]. IPv6: Current Deployment and Migration Status--International Journal of Research and
Reviews in Computer Science (IJRRCS)
[9]. Fahim A. Ahmed Ghanem And Vilas M. Thakare, “Optimization of IPv6 Packet’s Headers
Over Ethernet Frame”, International Journal of Electronics and Communication Engineering
& Technology (IJECET), Volume 4, Issue 1, 2013, pp. 99 - 111, ISSN Print: 0976- 6464,
ISSN Online: 0976 –6472.
[10]. Fahim A. Ahmed Ghanem and Vilas M. Thakar, “Compatibility Between the New and the
Current IPv6 Packet Headers”, International Journal of Electronics and Communication
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0976- 6464, ISSN Online: 0976 –6472.
[11]. Fahim A. Ahmed Ghanem and Vilas M. Thakare, “Compatibility Between the New and the
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