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Internet Core Protocols: The Definitive Guide
book

Internet Core Protocols: The Definitive Guide

by Eric Hall
February 2000
Intermediate to advanced content levelIntermediate to advanced
464 pages
15h 57m
English
O'Reilly Media, Inc.
Content preview from Internet Core Protocols: The Definitive Guide

TCP/IP Protocols and Services In-Depth

Whenever data is exchanged between two applications across a TCP/IP network, each of the major layers provided by TCP/IP come into play.

This can be seen with email clients that use the Simple Message Transfer Protocol (SMTP) to send mail to a local server, as is shown in Figure 1.5. The email software on the client contains local application-specific code for parsing and displaying email messages, but everything else is done with network protocols such as SMTP, TCP, and IP.

Some of the layers used by TCP/IP applications
Figure 1.5. Some of the layers used by TCP/IP applications

As data is passed through each of the different layers, packets are generated that contain two distinct elements: headers and data. As information is passed down through the protocol stack, each layer encapsulates the previous layer’s information (including both the header and the data) into a new packet, containing a new layer-specific header and the newly minted data segment. This process is shown in Figure 1.6.

The sub-parts of layers
Figure 1.6. The sub-parts of layers

At the bottom-most layer, the physical network is used to transfer bits of data (called “frames”) between two devices on the network. IP packets are contained within these network-specific frames. The only reason IP is used for this process is because the data can go over a ...

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Publisher Resources

ISBN: 1565925726Supplemental ContentErrata Page