ENVS 1000 Lecture Notes - Lecture 22: Simple Mail Transfer Protocol, Internet Protocol Suite, Telnet
10 May 2018
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ENVS 1000 Lecture 22 Notes – TCP/IP
Introduction
• Although the name suggests two protocols, TCP/IP is actually a name encompassing an
integrated suite consisting of numerous protocols that control various aspects of data
communication, including modem communication, communication through a gateway,
error reporting, address resolution, and many other functions.
• There are also a number of perhaps familiar application protocols, including HTTP,
telnet, ftp, smtp, and many more.
• The TCP/IP model consists of five layers.
• Each layer represents an attempt to isolate a single factor that is relevant to
communication between computers and other devices.
• The five layers in the model, along with some of the major protocols found at each
layer.
• In addition to the layer names, each layer is also identified by a layer number, starting
from 1 at the lowest layer.
• The operation of the TCP/IP model.
• As you can see from operation of the model is hierarchical.
• Each layer of the model is implemented to fulfill a specific function in the
communication process.
• Each layer at the sending node performs its services, and adds additional data to the
message, usually in the form of a header that encapsulates the data from above.
• A few protocols also require a trailer.
• The result is then passed to the next lower layer.
• This is also shown in the diagram.
• Each layer relies on the layers below it to provide all the additional functionality
necessary to fulfill the communication function.
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