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Networks
Defining a Network
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A computer network is a collection of computers and
peripheral devices connected by communication links
that allow the network components to work together.
Networks allow for communication between people
and the sharing of information between people,
computers, and devices.
Networks in Today’s Society
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Common examples of networks:
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The Internet
ATMs (connected to a bank)
Printers (connected to one or more computers)
Networks allow information (knowledge, opinions,
culture, etc.) to be quickly spread across the globe.
Local and Remote Networks
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Personal Area Networks (PAN) connect computers and
devices within a room
Local Area Networks (LAN) connect computers and
devices within a building
Wide Area Networks (WAN) connects computers and
devices between cities or countries
Wired vs Wireless
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Computers in wired networks are physically
connected with wires or cables.
Computers in wireless networks are connected via
radio waves, satellites, etc.
A cell network divides land into cells, each of which
has a base station transceiver.
Remote Communication
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Remote communication allows two users or systems to
communicate independent of their location.
Examples include online storage, cloud computing,
remote desktop, etc.
Components of Network Communication
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Understand how media, medium, message are
related
Communication Devices
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Common connection devices:
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Switches (links devices to create a network)
Routers (links networks)
Modem (converts analog data from telephone lines to the digital
form used on computers)
Cable modem (a digital modem used for high-speed Internet
services)
DSL (digital subscriber line. Transmits digital data over telephone
wires)
Network Medium Types:
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Twisted pair (copper wires)
CAT 6 (standardized cable for Gigabit Ethernet)
G3 (wireless connection used for PANs)
Bluetooth (wireless technology standard for exchanging data over
short distances)
Fiber optic (a glass fiber that uses pulses of light to transmit data)
Network Operating Systems
(NOS)
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The software that runs on a server.
Enables the server to manage connections, security,
and the storage and transfer of data
Common NOS’s include:
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UNIX
Microsoft Windows Server
Mac OS X
Packets
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Data sent over a network is divided up into small
chunks called packets.
A packet consists of
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the data to be sent (called payload)
a header with control information (such as source and
destination addresses, sequencing information, and a checksum
to check whether the packet arrives uncorrupted)
Protocols
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A protocol is a set of rules that govern the behavior of a
network. These rules allow all hosts on a network to
cooperate together.
Examples of rules:
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Each packet shall be 100 bytes in size
If a host is down, it will inform all other hosts on the network
Examples of protocols:
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TCP/IP (provides reliable delivery)
UDP (provides unreliable delivery)
FTP (used to transfer files)
HTTP, HTTPS (the foundation of the world wide web)
Protocol Stack
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A collection of protocols that governs the transfer of data
across all levels of hardware and software.
Careers and Educational Options in
Network Administration
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Certifications:
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Educational opportunities:
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CIW
CompTia
Cisco Certified Network Associate (CCNA)
A.S. or B.S. Network Administration
Career opportunities:
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Network administrators / engineers / technicians
Network security
Network analysis
Network Simulation
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Three people are selected to be hosts; everyone else is a router.
Two hosts write a two or three sentence message to send to the third host.
The message is split up into packets using notecards:
 Five words to a packet
 Each packet also contains the name of the sender and the receiver, as
well as the packet number.
The routers transmit these packets to the receiving host. They may lose
packets or corrupt them by scribbling out or rewriting part of the message.
The receiving host must put the packets of each message in order and
reply to them using the same method.
If the receiving host is missing a packet or receives a corrupted packet,
he/she sends a one-packet request for that packet to be re-sent.