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The TCP/IP Guide  9  Networking Fundamentals       9  Fundamental Network Characteristics

Connection-Oriented and Connectionless Protocols 1 2 Message Formatting: Headers, Payloads and Footers

Many networking technologies are based on packet switching, which involves the creation of small chunks of data to be sent over a network. Even though the word “packet” appears in the name of this method, the data items sent between networked devices are most generically called messages. “Packet” is one of a variety of similar words that are used in different contexts to refer to messages sent from one device to another.

In some cases these different terms can be very useful; simply the type of name used for the message can tell you something about what the message contains. In particular, different message names are usually associated with protocols and technologies operating at specific layers of the OSI Reference Model. Thus, the use of these different names can help clarify discussions that involve multiple protocols operating at different layers.

Unfortunately, these terms can also cause confusion, because they are not always applied in a universal or even consistent manner. Some people are strict about applying particular message designations only to the appropriate technologies where they are normally used, while others use the different terms completely interchangeably. This means that you should be familiar with the different message types and how they are normally used, but be prepared for the unexpected.

Connection-Oriented and Connectionless Protocols 1 2 Message Formatting: Headers, Payloads and Footers