TCP/IP protocol overview and functions

¶ … TCP/IP Protocol Suite

For the average computer user, TCP/IP probably doesn't mean a whole lot, except maybe when it comes to "configuring" their computer so they can get online, but without the TCP/IP protocol, the activity experienced on the Internet up until this point would not be possible. This paper will examine some of the components of the TCP/IP protocol and explore their uses as they apply to relevant parts of the Internet.

TCP/IP is the acronym for Transmission Control Protocol/Internet Protocol, which was originally established by the Department of Defense in 1993 to connect defense department computers with other computer networks. This network grew to include government and educational institution computers and eventually it has grown to include the widespread use of commercial and private networks.1

Simply put, TCP/IP "allows cooperating computers to share resources across a network." 2 Developed by Department of Defense researchers, TCP/IP once revolved around that ARPAnet.2 Over the years, it has become an integral part of the network of networks assisting computer users with anything from sending a simple piece of electronic mail to processing a sensitive business transaction.

Taking a closer look, the TCP/IP protocol can be seen as a communications protocol with three layers. One layer is the Internet protocol (IP), which is responsible for moving data from computer to computer. Transmission Control Protocol/Internet Protocol (TCP) is a layer which verifies the delivery of data. Another layer of the TCP/IP protocol is referred to as sockets, which are packages of "subroutines that provide access to TCP/IP on most systems." 3

According to Jim Carr, in an article published in NetworkMagazine.com, the TCP and the IP part of TCP/IP must work together to insure the best delivery of information, which is the basic function of this protocol. The IP part of the protocol is responsible for receiving, or accepting data and the TCP part ensures that the data is delivered "error-free, in the order it was sent, and without loss or duplication."4

TCP and IP actually represent a family of many protocols, with TCP/IP being the common term used when speaking of any one of those protocols. For instance, different protocols allow computers to do different things such as transferring files or sending or receiving mail. One of the most important services of TCP/IP is the ability to transfer files, commonly referred to as FTP, which allows a user on one computer to get files or a part of a file from another computer. Another popular service TCP/IP allows is the remote logon, which allows a user to access to a network system from a computer at a remote location. Probably the most popular, or at least one of the most common, uses provided by TCP/IP is electronic mail. Other services TCP/IP offers are data formatting, encryption, and the transmission of binary data over a communications network.5

The TCP/IP protocol model is known as the DARPA model and the architecture of that model are application, transport, Internet and network interface. Each layer of the DARPA model corresponds to one of the layers in the ISO/OSI model.

ISO/OSI is the standard model of connection, which has its own set of layers and functions that are worth mentioning. ISO/OSI layers include application, presentation, session, transport, network, data-link, and physical. In addition to the protocols already mentioned, the ISO/OSI model also supports MIME, BOOTP, ASCII, IEEE, IGMP, and MTU protocols, just to mention a few. 6

The framework of TCP/IP is composed of an Internet layer, a transport layer and an application layer. Components of the Internet layer include ARP (responsible for the resolution of the address), ICMP (which provides diagnostics on errors or conditions) and IGMP (which is responsible for multicast management). The transport layer consists of TCP and UDP (which provides transmission of small amounts of data). The application layer of TCP/IP includes HTTP (which is used to transfer the language of the Internet), FTP (which is used for the transference of files), SMTP (used to transfer electronic mail and attachments) and Telnet (which is necessary for remote logins).7

As shown, TCP/IP has many uses and creates an incredible variety as far as what can be sent, downloaded, viewed and accessed across the Internet and networks alike. With all of that variety and availability, one has to wonder about security. TCP/IP does have standards, though. These standards are called Requests for Comments or RFCs. RFCs "describe the inner workings of the Internet... TCP/IP standards are always published as RFCs, although not RFCs specify standards."8

It may seem like information overload to some, and the end user can leave most of it running in the background. TCP/IP is easily installed on most computers, if the computer doesn't come with it installed already. Important to the user would be his or her IP address, especially if working remote.9