In this report, we will examine the basic characteristics of the IPv6 and Its several major features that the Improvements that It contributes to the future of Internet. Historical overview In this section, a brief history of the Internet and Internet Protocol will be explored. We will also examine the design limitation of the Internet Protocol version 4 which motivated the development of Internet Protocol version 6. 2. 1 The Beginning of Internet The development of Internet Protocol began in the 196Us motivated by the advancement In mainframe computers [1].

American computer scientist Joseph Carl Robnett Llckllder first proposed the idea of a global data-exchange network In his with Weldon Clark and published "On-line man computer communication" in 1962 hich further articulated the idea of the future of a computer network. Licklider was then hired by the Defense Advance Research Project Agency also known as "DARPA" to help the United States Department of Defense to interconnect its mainframe computers.

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During this time, Licklider formed a three-terminal research network from his office to three different computers located at System Development Corporation in Santa Monica, University of California in Berkeley and the Massachusetts Institute of Technology (MIT) in Cambridge [2]. At the time however, these three separate erminal networks could not communicate with each other. To exchange information, one has to log onto each terminal separately and manually copy information received from one terminal to another. The inability to communicate interactively soon became an important issue to resolve.

In 1968, Licklider's successor Rob Taylor and Ivan Sutherland helped completing this objective by developing a new type of network capable of exchanging information with a method called "packet switching". That network was the modern Internet's predecessor ARPANET. As the first functional "packet switching" computer network, ARPANET allowed more han two end user terminals to communicate with each other without having the need to have dedicated communication links for every two of terminal. Messages were broken down into packets that could then being routed from one host to any other destination host on the network [3].

Many other packet-switched networks were then developed by various technological research institutes in the United States and Europe. By the early 70's, at least six of such network were operational in the world including Telenet, Merit and NPL. However, all of these networks used different communication protocols despite sharing the same fundamental way of data ransmission. It soon be came a problem that all networks were independent and therefore were unable to inter-communicate with one-another. The situation motivated American Computer Scientist Bob Kahn and Vinton Cerf to work together towards a network reformation.

This effort eventually produced the Internet Protocol Suite which became the standard protocol that universally defined the basis of modern Internet today. 2. 2 Internet Protocol Suite In the summer of 1973, Kahn and Cerf increased their network protocol's portability by simplifying its responsibility to strictly traffic routing. The hosts became the handler of other tasks that the protocol used to perform. This design concept enabled the same protocol to be used on virtually any network despite the type of hardware, operating system and application.

A year later, details of the protocol were published in the very first Transmission Control Program Specification [4]. In the following years, DARPA funded the actual development and implementation of the Transmission Control Program on hardware platforms and operating systems. Three versions of the protocol were completed in the late 70's and the stable fourth ersion - known today as TCP/IP v4, was deployed in 1981 and remained as the The Transmission Control Program have been divided into two major protocols during the 80's - the Transmission Control Protocol and Internet Protocol.

They became known later as the "Internet Protocol Suite". With the introduction of "encapsulation" as a concept in other areas of computer science at the time, major functions within the original protocol have been subsequently divided into various "layers" according to the practice. The "Internet Protocol" is the principle communication protocol for the "Internet Layer" responsible for addressing between etwork hosts and relaying/routing of packets across the network topography. The Internet Protocol version 4 uses a 32 bit addressing system, which enables the protocol to globally identify approximately 4. billion unique hosts on the public Internet. However, as the development of Internet gradually transitioned from institutional research into commercialization, it became obvious to developers that the amount of address required to allocate to the rapidly growing global end users was far from enough. Available addresses were depleting in a concerning rate in the 1980s, and imminent shortage was soon anticipated. Thus In the early 90s, new technologies were employed to slow down the rate of address exhaustion.

In 1991 , the Internet Engineering Task Force (IETF), the Internet standard organization established in 1986, have created the Routing and Addressing Group (ROAD) to tackle the situation[6]. By 1993, several techniques were proposed and have now become standard operational procedures in most networks. These include Classless Inter- domain Routing (CIDR), Network Address Translation (NAT), and Dynamic Host Configuration Protocol. These new techniques were aimed the goal of making the usage of limited public ddresses space more efficient.

The CIDR allows service providers to allocate address space of any size to end users and organizations, thus reduce wastage of addresses in the class block addressing system. NAT then allows multiple end user to share a single public address by making their addresses inaccessible in the global domain. Dynamic Host Confguration Protocol enables empty addresses to by freely allocated to the active devices only, thus prevent inactive devices occupying IP address when not required. Because of these innovations, the life of IPv4 have been significantly xtended and thus still remains the standard communication protocol of the Internet.

However, the procedure of confguring any network devices have been made significantly more complex and has very little flexibility and mobility. The use of NAT have largely inhibited end user's end-to-end connectivity. The extra network devices required to perform these procedures also create more bottle-necks and thus impact performance. With the intention to eliminate all the shortcomings of IPv4, the IETF developed a brand new protocol - IPv6. 3 Closer look at ipv6 examine the major features of this protocol and compare them with that of IPv4 to ain a better understanding of the advantages that they offer. . 1 Address space The major issue that IPv6 set to resolve was the limited addressing space provided by IPv4. With an addressing length of 32-bit, the maximum amount of public addresses that the current protocol can manage is 2A32 ” 4. 3 billion. To increase this limit, more bits will have to be added to the overall length of the address. To fundamentally mitigate the problem, IPv6 increased the address length to 128-bits, and can support up to an astonishing 2A128 ” 340 undercillion addresses.

To put things in erspective, if the entire address space were to be allocated to every single living human being in the world today in equal portions, each person would have 50 octocillion IP addresses. That is more than quintillion times the addresses currently allocated to the entire world [7]. This generous and future-proof design completely eliminated not only the mere quantitative shortage of allocatable resources, but also problems associated with NAT and DHCP. With IPv6 it is possible for end user to gain direct point-to-point connectivity to node on the world and global networking simpler and more transparent.

The new addressing format also provides other benefits besides its shear size. Routing have been made much more efficient despite having to manage many more addresses. This is due to its hierarchical design that advocates route aggregation by default, which prevents the explosive growth of routing tables by combining multiple sub-networks together into super-networks with route to each sub-network summarized by a CIDR prefix. Router performance is then subsequently improved because of the reduction of space required to store routing information and reduced calculation overhead when matching routes. . Packet format Since packets are the basic data transmitting units in a packet-switched network, packet handling techniques can drastically impact its performance and reliability of a protocol. Similar to IPv4, Pv6 packet has two parts: header and payload. The header contains control information required by the router to relay it to the correct destination, and the payload contains the host/user data that the packet is responsible of transmitting. An IPv6 header is considerably larger than that of IPv4 since it has to carry the much longer 128-bit address.

However, despite occupying 320bits, the new acket header only has eight-fields in contrast to the 14 fields of the old format. Non- essential information was removed from the header to improve router performance and efficiency. Meanwhile, it has the option to include a "header extension", a useful feature that allows other fields to be added after the fixed header to provide extra services upon request. Thus it still allows extra fields that were rarely used in IPv4 to be added in situations where it's required without compromising any capability.

In fact, header extension makes the future development of more powerful features and nhancements possible without revamp to the protocol, making it more much To make the packet handling even simpler on the "Internet layer", some of the essential tasks that the router used to perform in IPv4 have been moved to the hosts instead. One of such tasks was "packet fragmentation". It is a process that breaks up packets into smaller fragments when their size exceed maximum transmission unit (MTIJ) limit of a network path. In IPv6, the same process is done at the host level using a method called "path MTIJ discovery'.

Before sending packets over the etwork, the MTIJ limit of the path en route would be acquired by the host, then it subsequently set their packet size according to the lowest size limit so that no further fragmentation is needed. Furthermore, tasks such as Integrity protection and error detections have also been moved to the hosts and the router is no longer required to recompute the packet header checksum every time a field in the header is modified [8]. 3. 3 Automatic configuration Pv6 was designed with restoring the global connectivity in mind and was aimed to improve the scalability and mobility of IPv4.

Because of the digitization of mobile ommunication devices such as cell phone and blackberry, and significant growth of mobile and wireless Internet, assisting technologies such as NAT and DHCP became limiting factors due the complicated manual confguration procedure required upon joining a network. An IT professional is usually required to setup the device according to the networks confguration parameter before a user can use the device. And the same procedure needs to be repeated when Joining the network from other nodes/access points. IPv6 solved this issue by implementing an automatic configuration feature using the

Internet Control Message Protocol version 6. When connecting to a network, the host sends a link-local router solicitation request for its configuration parameters, and the router then response with an advertisement packet that contains the requested parameters for the host to confgure its network settings automatically without user interference. This eliminated the need for a user or IT professional to perform the procedure manually and enables instant connectivity to any available network anywhere and anytime. 3. 4 other features There are many other features that further enhance the capability of the new rotocol.

Various modes of multicasting enable certain packet to be sent to multiple destinations, and replaced the broadcast method of IPv4 to make better usage of network resources. IP Security is also a mandatory feature in IPv6 which makes the protocol less vulnerable to attacks. The support for Jumbogram enables more "payload" to be carries in a single packet on links with higher MTIJ and increases performance. Triangular routing of the mobile IPv4 is also eliminated in the mobile version of IPv6 and making it Just as reliable and capable as native IPv6. world wide transition pace comparable to the size of our solar system, IPv6 became the inevitable future of global communication via the Internet. However, the process of transitioning the world into using it isn't going to be easy. In this section we will examine the various aspects of what it takes to deploy IPv6. 4. 1 Transition mechanisms Because of the size and complexity that modern Internet has evolved into, the migration to new protocol will have to be done in a progressive way, which implies that applications, operating systems and infrastructures have to allow the two protocols to coexist.

Networks closer to the end user level such as tier three Internet service providers, business networks and home networks might still be using IPv4 during most of the transition. Gradually, these users will have to access IPv6 Internet services over the IPv4 infrastructure before the transition is complete. This can be done using a technique call "6in4 protocol tunneling" which encapsulates IPv6 packets with a special type of IPv4 header designated for this special purpose [12]. On the software side, similar mechanisms need to be implemented for applications and operating systems to handle both protocols interchangeably.

Despite some similarities, the version 6 protocol stack is fundamentally different from its predecessor. An operating system that supports the two protocols may have two completely independent IP stacks one for each version; commonly referred to as "dual-stack". This particular implementation provide applications with separate programming interface and leaves it up to the programmers to decide how their program will go about handling the two protocols. Such a design decision however, does make application development less flexible since the programmer have to specify which protocol to use in the code.

Newer operating systems however, have gotten around this problem by providing a "hybrid-stack" implementation which uses one IP stack capable of handling both IPv6 and IPv4 traffic while providing the programmer with only one application interface. Coding for backward compatible programs became more flexible and transparent. 4. 2 Hardware Support To facilitate Pv6 transition at the hardware level, certain modifications and upgrades needs to be applied to assets such as router, switch and modem, which are responsible for the forwarding of IPv6 packets.

However, major hardware vendors uch as Cisco have already being working closely with International organizations such as IETF to develop IPv6 support in their products. Currently, all network devices manufactured by Cisco are compatible with IPv6. Furthermore, firmware upgrades have also been developed for legacy hardware to handle new addressing and packet formats provided that the device have adequate design to permit such an upgrade. s network cables, adapters, fibre lines and unmanaged "dumb" switches need little to no upgrade; making large portions of existing infrastructure reusable an thus void costly structural revamps. 4. 3 transition progress With the last few blocks of International IPv4 addresses running out, the transition towards IPv6 became inevitable. Major steps have been taken around the world to accelerate the full globalization of IPv6 in every aspect of network computing.