TCP/IP
Chris Bolte
NTC/405
October 26, 2014
Bradly Rush

The basic communication language, or protocol, for the Internet is Transmission Control Protocol/Internet Protocol (TCP/IP) and is a two layer program. The Transmission Control Protocol (TCP) is the higher layer, providing services that ensure accurate and timely delivery of network communications between two hosts. Some of the services provided by TCP are sequencing of data packets, flow control, and error checking. Internet Protocol (IP), the lower layer, handles the address part of each packet so that it gets to the right destination (Rounse, nd). Using the client/server modes, each gateway computer on the network checks this address to see where to forward the message. The Open Systems Interconnection (OSI) model is a theoretical way of classifying and talking about the complex process of sending data on a network. The OSI model, although theoretical, is the most widely used method for understanding and talking about network communications. There are seven layers on the OSI model: in order; physical, data link, network, transport, session, presentation, and application. There are plenty of advantages to the concepts of the OSI model, including providing a reference point between network professionals, dividing networking tasks into logical layers, for easier comprehension, and aiding in troubleshooting. Other advantages include the promotion of standards of interoperability between networks and devices, allowing specialization of features at different levels, and the ability to change features without changing the entire approach (Mitchell, nd). However, whenever there are advantages, there are also disadvantages. The disadvantages of the OSI model may include that they are actually theoretical and technically do not perform real functions, industry implementations rarely have a layer-to-layer correspondence with the OSI layers, and different protocols within the stack perform different functions that help send or receive the overall message. In addition, a particular protocol implementation may not represent every OSI layer. The TCP/IP model incorporates the general concepts and structure of the OSI model. The layers of the TCP/IP model are as follows:
Application – The application layer corresponds to the Session, Presentation, and Application layers of the OSI model. Protocols associated with the Application layer include FTP (File Transfer Protocol), HTTP (Hyper Text Transfer Protocol), Telnet, SMTP (Simple Mail Transfer Protocol), DNS (Domain Name Service), and SNMP (Simple Network Management Protocol).
Host-to-host – The Host-to-host layer is comparable to the Transport layer of the OSI model and is responsible for error checking and reliable packet delivery. Here, the data stream is broken into segments that must be assigned sequence numbers so that the segments can be reassembled correctly on the remote side after they are transported. Protocols associated with the Host-to-host layer include TCP and User-Datagram Protocol (UDP).
Internet – The Internet layer is comparable to the Network layer of the OSI model. It is responsible for moving