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Perspectives on Networking

So, you are new to networking. Like many people, your perspective about networks might
be that of a user of the network, as opposed to the network engineer who builds networks.
For some, your view of networking might be based on how you use the Internet, from
home, using a high-speed Internet connection like digital subscriber line (DSL) or cable TV,
as shown in Figure 1-1.
Free CISCO CCNA Routing and Switching ICND1 Study Guide
Figure 1-1 End-User Perspective on High-Speed Internet Connections
The top part of the figure shows a typical high-speed cable Internet user. The PC connects
to a cable modem using an Ethernet cable. The cable modem then connects to a cable TV
(CATV) outlet in the wall using a round coaxial cable—the same kind of cable used to connect
your TV to the CATV wall outlet. Because cable Internet services provide service continuously,
the user can just sit down at the PC and start sending email, browsing websites,
making Internet phone calls, and using other tools and applications.

The lower part of the figure uses two different technologies. First, the tablet computer uses
wireless technology that goes by the name wireless local-area network (wireless LAN), or
Wi-Fi, instead of using an Ethernet cable. In this example, the router uses a different technology,
DSL, to communicate with the Internet.

Both home-based networks and networks built for use by a company make use of similar
networking technologies. The Information Technology (IT) world refers to a network created
by one corporation, or enterprise, for the purpose of allowing its employees to communicate,
as an enterprise network. The smaller networks at home, when used for business
purposes, often go by the name small office/home office (SOHO) networks.

Users of enterprise networks have some idea about the enterprise network at their company
or school. People realize that they use a network for many tasks. PC users might realize that
their PC connects through an Ethernet cable to a matching wall outlet, as shown at the top
of Figure 1-2. Those same users might use wireless LANs with their laptop when going to a
meeting in the conference room as well. Figure 1-2 shows these two end-user perspectives on an enterprise network.
Free CISCO CCNA Routing and Switching ICND1 Study Guide
Figure 1-2 Example Representation of an Enterprise Network
NOTE In networking diagrams, a cloud represents a part of a network whose details are
not important to the purpose of the diagram. In this case, Figure 1-2 ignores the details of
how to create an enterprise network.

Some users might not even have a concept of the network at all. Instead, these users just
enjoy the functions of the network—the ability to post messages to social media sites, make
phone calls, search for information on the Internet, listen to music, and download countless
apps to their phones—without caring about how it works or how their favorite device connects
to the network.

Regardless of how much you already know about how networks work, this book and the
related certifications help you learn how networks do their job. That job is simply this: moving
data from one device to another. The rest of this chapter, and the rest of this first part
of the book, reveals the basics of how to build both SOHO and enterprise networks so that
they can deliver data between two devices.

In the building business, much work happens before you nail the first boards together. The
process starts with some planning, an understanding of how to build a house, and some
architectural blueprints of how to build that specific house. Similarly, the journey toward
building any computer network does not begin by installing devices and cables, but instead
by looking at the architectural plans for those modern networks: the TCP/IP model.

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