Introduction to Computer Networks TCP/IP - Research Paper Example

Farzeela Academia Research Jan-29-2006 Continued growth of the global Internet has leaded us to think in multidimensional ways from the early research prototype to a global communication system throughout the world. IP (Internet Protocol) has made it possible for the Internet to handle heterogeneous networks, detect and modify dramatic changes in hardware technology. To handle heterogeneity, IP defines IP datagram 1 (Uniform packet format) and a packet transfer mechanism. IP also defines a set of addresses that allow applications and higher layer protocols to communicate across heterogeneous networks without knowing the differences in hardware addresses used by the underlying network systems. IP has also accommodated changes in hardware technology. Although the protocol was defined before the commercial usage of LAN technologies, the original design has continued to work well through several generations of hardware technologies. IP is now used over networks that operate several orders of magnitude faster than the networks that were in use when IP was designed. The Motivation for Change In TCP/IP If IP works so well, why a need is felt to change The primary motivation for change arises from the limited address space. When IP was defined, only a few compute networks existed. The designers decided to use 32 bits for an IP address because doing so allowed the Internet to include over a million networks. However, with a rapid exponential growth in the global Internet, the primary motivation for defining a new version of IP arose from the address space limitation, as larger addresses are necessary to accommodate continued growth of the Internet. Besides addressing, the most common problems faced by the TCP/IP were routing and connectivity issues. Secondary motivations for changes in IP have risen from new Internet applications. For example, applications that deliver audio and video need to deliver data at regular intervals. To keep such information flowing through the Internet without disruption, IP must avoid changing routes frequently. Although the current IP datagram header includes a field that can be used to request a type of service, the protocol did not define a type of service that can be used for real-time delivery of audio and video. New applications are being developed that require more complex addressing and routing capabilities. Thus, a new version of IP needs to include mechanisms that make addressing and routing possible. (Douglas) The current version of IP, which possesses the main drawback of address space, routing and connectivity, is version 4 so it is referred to as Ipv4. Ipv6 is the official name of IPng (Internet Protocol next generation) Features of Ipv4 and Ipv6 1. Connectionless - each datagram contains a destination address, and each datagram is routed independently. 2. The header in a datagram contains a maximum number of hops the datagram can take before being discarded. 3. Ipv4 places key information in fixed fields of the header and only appends variable-length options for less important information while Ipv6 header is always of variable size. (Douglas) Reasons for changing Ipv4 to Ipv6 Larger and better Network management of Address Space: The most considerable reason for the decision of changing from Ipv4 to Ipv6 is the smooth management of the IPv6 network. As the answer to the lack of address space, IPv6 holds a potential for a network the size of which has never been seen before. The manner in which the network is managed will to a great extent determine whether this huge network will function. The main objectives, which are visualized in network management, would be: 1. Display the distinct hierarchy embedded in the IPv6 address architecture, 2. Show topographical data simultaneously to the hierarchy, 3. Make peripheral data easily available, and 4. In doing so, aid in the process of network management. Ipv6 research and ideology basically revolves around network management. This is because most of the problems in IPv4, which IPv6 is created to overcome, are not problems in how the protocol functioned, but in what the protocol is prepared to handle. IPv4 was simply not made to handle networks of the gigantic proportions of today. Many of IPv6's new capabilities are created to handle larger sizes. One of these capabilities is the manner of registration. The registry system for IPv6 in many ways should mimic that of IPv4, which provides limited management information. However, as the IPv4 network grew to hitherto unforeseen proportions, even as the need for more address space became more and more urgent, it was evident that the centralized management of addresses was becoming more and more difficult. IPv6 has come about as a solution to the demand for more address space than IPv4 could provide. However, if address management were difficult in IPv4 because of its great size, then address management for IPv6 would be many times that in difficulty. IPv6 supports an infinitely larger, multi-layered network. Registration items such as address prefix, organization name, and so on would have to be kept for each and every organization that registers for an address. (Shu, Yuji, Jun) Elimination of "Addressing Kludges": Technologies like NAT are effectively "kludges" that make up for the lack of address space in IPv4. IPv6 eliminates the need for NAT and similar workarounds, allowing every TCP/IP device to have a public address. Easier TCP/IP Administration: The designers of IPv6 hoped to resolve some of the current labor-intensive requirements of IPv4, such as the need to configure IP addresses. Even though tools like DHCP eliminate the need to manually configure many hosts, it only partially solves the problem. Modern Design for Routing: In contrast to IPv4, which was designed before we all had any idea what the modern Internet would be like, IPv6 is created specifically for efficient routing in our current Internet, and with the flexibility for the future. Multicasting, Security and Mobility: Multicasting was an option under IPv4 from the start, but support for it has been slow in coming. IPv4 was designed at a time when security wasn't much of an issue, because there were a relatively small number of networks on the Internet, and their administrators often knew each other. Today, security on the public Internet is a big issue, and the future success of the Internet requires that security concerns be resolved. When IPv4 was created, there really was no concept of mobile IP devices. The problems associated with computers that move between networks led to the need for Mobile IP. IPv6 builds on Mobile IP and provides mobility support within IP itself. (TCP/IP Guide) New features in Ipv6 1. Address Size: Instead of 32 bits, each Ipv6 address contains 128 bits. The resulting address space is large enough to accommodate continued growth of the world-wide Internet for many decades. 2. Header Format: The Ipv6 datagram header is completely different than the Ipv4 header. Almost every field in the header has been changed; some have been replaced. 3. Extension Headers: Unlike Ipv4, which uses a single header format for all datagrams, Ipv6 encodes information into separate headers. A datagram consists of the base Ipv6 header followed by zero or more extension headers, followed by data. 4. Support for audio and video: Ipv6 includes a mechanism that allows a sender and receiver to establish a high- quality path through the underlying network and to associate datagrams with that path. Although the mechanism is intended for use with audio and video applications that require high performance guarantees, the mechanism can also be used to associate datagrams with low-cost paths. 5. Extensible Protocol: Unlike Ipv4, Ipv6 does not specify all possible protocol features. Instead, the designers have provided a scheme that allows a sender to add additional information to a datagram. The extension scheme makes Ipv6 more flexible than Ipv4 with an additional facility to add new features to the design as and when required. (Douglas) Broadcasting Methods: Included in IPv6 are a number of new broadcasting methods: Unicast - a communication between a single host and a single receiver. Packets sent to a unicast address are delivered to the interface identified by that address. Multicast - Multicast is communication between a single host and multiple receivers. Packets are sent to all interfaces identified by that address. Anycast - Packets sent to an anycast address or list of addresses are delivered to the nearest interface identified by that address. Anycast is a communication between a single sender and a list of addresses. (Ipv6) References Douglas E. Comer, Computer Networks and Internets with Internet Applications. Third Edition. Ipv6, Documentation Available from < http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ipv6 > Shu, Yuji, Jun. A Study into a Visualization of an Ipv6 Network Available from < http://www.isoc.org/inet99/proceedings/4s/4s_1.htm > TCP/IP Guide, Ipv6 Motivation and Overview Available from < http://www.tcpipguide.com/free/t_IPv6MotivationandOverview-3 > Read More