The TCP/IP suite is a layered model similar to the OSI reference model. Its name is actually a combination of two individual protocols, Transmission Control Protocol (TCP) and Internet Protocol (IP). It is divided into layers, each of which performs specific functions in the data communication process. Both the OSI model and the TCP/IP stack were developed by different organizations at approximately the same time as a means to organize and communicate the components that guide the transmission of data.
Although the OSI reference model is universally recognized, the historical and technical open standard of the Internet is the TCP/IP protocol stack. The TCP/IP protocol stack, varies slightly from the OSI reference model.The TCP/IP protocol stack has four layers. Note that although some of the layers in theTCP/IP protocol stack have the same names as layers in the OSI reference model, the layershave different functions in each model, as is described in the following list:
Although the OSI reference model is universally recognized, the historical and technical open standard of the Internet is the TCP/IP protocol stack. The TCP/IP protocol stack, varies slightly from the OSI reference model.The TCP/IP protocol stack has four layers. Note that although some of the layers in theTCP/IP protocol stack have the same names as layers in the OSI reference model, the layershave different functions in each model, as is described in the following list:
■ Application layer: The application layer handles high-level protocols, including issues of representation, encoding, and dialog control. The TCP/IP model combines all application-related issues into one layer and ensures that this data is properly packaged for the next layer.
■ Transport layer: The transport layer deals with QoS issues of reliability, flow control,and error correction. One of its protocols, TCP, provides for reliable network communications.
■ Internet layer: The purpose of the Internet layer is to send source datagrams from any network on the internetwork and have them arrive at the destination, regardless of the path they took to get there.
■ Network access layer: The name of this layer is broad and somewhat confusing. It is also called the host-to-network layer. It includes the LAN and WAN protocols and all the details in the OSI physical and data link layers.
■ Transport layer: The transport layer deals with QoS issues of reliability, flow control,and error correction. One of its protocols, TCP, provides for reliable network communications.
■ Internet layer: The purpose of the Internet layer is to send source datagrams from any network on the internetwork and have them arrive at the destination, regardless of the path they took to get there.
■ Network access layer: The name of this layer is broad and somewhat confusing. It is also called the host-to-network layer. It includes the LAN and WAN protocols and all the details in the OSI physical and data link layers.
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