26-09-2013, 04:31 PM
AN INTRODUCTION TO TCP/IP
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ABSTRACT :-
One of the most important achievement of last decade is popularity of internet. Today internet has become part of our day to day life.TCP/IP in a broad sense can be explained as the concept on which internet works.The paper attempts to familiarize with some of the basic concepts of TCP/IP.It starts with a brief introduction of TCP/IP and provides the basics of it.It also gives a brief origin of TCP/IP and the basic function of these protocols.It also gives the structure of TCP/IP and explains how transmission of data takes place in real world network.It also gives description of some of the protocols that constitute TCP/IP.The conclusion summarizes the key points of TCP/IP.
INTRODUCTION
Most of us know of TCP/IP as the glue that binds the Internet. But not as many can offer a cogent description of what it is and how it works. So what is TCP/IP, really?
TCP/IP is a means for networked computers to communicate with each other. It doesn't matter whether they are part of the same network or are attached to separate networks. It doesn't matter if one computer is a Cray and the other a Macintosh. TCP/IP is a platform-independent standard that bridges the gap between dissimilar computers, operating systems, and networks. It's the protocol that drives the global Internet, and it is to the Internet that TCP/IP owes much of its popularity.
Understanding TCP/IP is largely a matter of understanding a collection of arcane protocols that TCP/IP hosts use to exchange information. Let's look at some of those protocols and see what makes TCP/IP tick
ORIGIN OF TCP/IP
TCP/IP is an outgrowth of research funded by the U.S. government's Advanced Research Projects Agency (ARPA) in the 1970s. It was developed so that research networks around the world could be joined to form a virtual network known as an internetwork. The original Internet was formed by converting an existing conglomeration of networks, known as ARPAnet, over to TCP/IP; that Internet would eventually become the backbone of today's Internet.
TCP/IP AND INTRANETS
The reason TCP/IP is so important today is that it allows standalone networks to be connected to the Internet or linked together to create private intranets. The networks that comprise an intranet are physically connected by devices called routers or IP routers. A router is a computer that transfers packets of data from one network to another. On a TCP/IP intranet, information travels in discrete units called IP packets or IP datagrams. TCP/IP software makes each computer attached to the network a sibling to all the others; in essence, it hides the routers and underlying network architectures and makes everything seem like one big network. Just as connections to an Ethernet network are identified by 48-bit Ethernet IDs, connections to an intranet are
identified by 32-bit IP addresses, which we express as dotted decimal numbers (for example, 128.10.2.3). Given a remote computer's IP address, a computer on an intranet or the Internet can send data to the remote computer as if the two were part of the same physical network.
BASIC FUNCTION OF TCP AND IP
TCP/IP provides a solution to the problem of how two computers attached to the same intranet but belonging to different physical networks can exchange data. The solution comes in several parts, with each member of the TCP/IP protocol suite filling in one piece of the puzzle. The most fundamental TCP/IP protocol, IP, transmits IP datagrams across an intranet and performs an important function called routing--choosing the path that datagrams will follow to get from A to B and using routers to "hop" networks.
USER DATAGRAM PROTOCOL
Another important member of the TCP/IP suite is the User Datagram Protocol (UDP), which is similar to but more primitive than TCP. TCP is a "reliable" protocol because it performs the error-checking and handshaking necessary to verify that data makes it to its destination intact. UDP is an "unreliable" protocol because it doesn't guarantee that datagrams will arrive in the order in which they were sent or even that they will arrive at all. If reliability is desired, it's up to the application to provide it. Still, UDP has its place in the TCP/IP universe, and a number of applications use it. The SNMP (Simple Network Management Protocol) application provided with most implementations of TCP/IP is one example of a UDP application.
OTHER IMPORTANT PROTOCOLS OF TCP/IP
Other TCP/IP protocols play less visible but equally important roles in the operation of TCP/IP networks. For example, the Address Resolution Protocol (ARP) translates IP addresses into physical network addresses, such as Ethernet IDs. A related protocol, the Reverse Address Resolution Protocol (RARP), does the opposite, converting physical network addresses into IP addresses. The Internet Control Message Protocol (ICMP) is a support protocol that uses IP to communicate control and error information regarding IP packet transmissions. If a router is unable to
forward an IP datagram, for example, it uses ICMP to inform the sender that there's a problem. For a summary of some of the other protocols that fall under the TCP/IP umbrella, see the sidebar above.