Transcript Networking

Chapter 8
Computer Networks
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Networking and Communications
Applications

Wireless phones
 Cellular phones
 Satellite phones

Paging and messaging

Global positioning systems (GPSs)

Satellite radio
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Networking and Communications
Applications, Cont’d.

Online conferencing (online meetings)
 Videoconferencing
 Web conferencing

Collaborative computing

Telecommuting

Telemedicine
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What Is a Network and How Does it
Transmit Data?

Computer network—a
collection of computers
and other hardware
connected together to
share data, hardware,
software, programs, and
facilitate electronic
communication.
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Data Transmission Characteristics

Analog (continuous wave) vs.
digital (discreet 0s and 1s).

Bandwidth and speed (higher
bandwidth allows more data to
travel at the same time).

Serial vs. parallel transmission.
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Data Transmission Characteristics,
Cont’d.

Transmission directions

Simplex transmission (one way only).

Half-duplex transmission (one way at a time).

Full-duplex transmission (both ways at the same
time).
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Data Transmission Characteristics,
Cont’d.

Transmission timing

Synchronous transmission

Asynchronous transmission

Isochronous transmission
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Wired vs. Wireless Connections

With a wired network connection, the PC is
physically cabled to the network.
 Common in schools, business, and government
facilities.

Wireless network connections allow great freedom
regarding where users can use their PCs.
 Increasingly common in homes, businesses, and
wireless public hot spots (e.g. Starbucks).
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Wired Network Transmission Media

Twisted-pair cable
 Pairs of wires twisted together.
 Used for telephone and network connections.

Coaxial cable
 Thick center wire.
 Used for cable TV and network connections.

Fiber-optic cable
 Glass or fiber strands through which light can pass.
 Used for high-speed communications.
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Wireless Network Transmission
Media

Broadcast radio transmissions (FM and AM radio
broadcasts, short-range networking and wireless
devices).

Microwave and satellite transmissions.
 Microwave stations
 Communications satellites

Cellular radio transmissions.
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Network Topologies

Star

Bus

Ring

Combination
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Network Architectures

Client-server networks



Client—makes requests of servers.
Server—fulfills client requests (for files, programs,
Web pages, etc.).
Peer-to-peer networks (all computers at the same
level)
 Often takes place via the Internet.
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LANs, WANs, and Other Types of
Networks

Personal area networks (PANs)

Local area networks (LANs)

Metropolitan area networks (MANs)

Wide area networks (WANs)

Internet
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LANs, WANs, and Other Types of
Networks, Cont’d.

Intranets and extranets

Virtual private networks (VPNs)

Storage area networks (SANs)
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Networking Hardware

Network adapters, also called network interface
cards (NICs).

Needed to connect PC to network.

Come in a variety of formats (internal or external,
wireless or wired, PC card, USB, etc.).
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Networking Hardware, Cont’d.

Modems (used to connect PC to the Internet)

Conventional
dial-up

ISDN

DSL

Cable

Satellite
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Networking Hardware, Cont’d.

Hubs, switches, and routers

Wireless access points

Gateways and bridges

Repeaters

Multiplexers and concentrators
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Communications Protocols

Communications protocol—an agreed-upon standard
for transmitting data between two devices on a
network.

Common wired protocols are Ethernet, Token Ring,
and TCP/IP.

Common wireless protocols are 802.11 (Wi-Fi),
Bluetooth, and WAP.
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Ethernet

Typically used with wired LANs.

Utilizes a set of procedures (CSMA/CD) to send data
and make sure it arrives.

Traditional (10Base-T) Ethernet networks run at 10
Mbps; newer 100 Mbps and 1 Gbps versions are now
available.
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Token Ring

Usually used
with a ring
network
topology and
utilizes a
token to send
and retrieve
data.
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TCP/IP

The protocol
used with the
Internet also
increasingly
being used with
LANs.

Sends data in
packets.
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802.11 (Wi-Fi) and Bluetooth

802.11 (Wi-Fi for wireless fidelity)—a family of
wireless networking standards.
 802.11b is the original standard (11 Mbps).
 802.11g is faster (54 Mbps) and expected to
eventually replace 802.11b.
 Newer versions are in development.

Bluetooth is a standard for low-cost, short-range,
wireless connections between Bluetooth-enabled
devices.
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Other Networking Protocols

Wireless Application Protocol (WAP)—for Web content
delivered to smart phones and other mobile devices.

IrDA—used for short range infrared data transfers.

Phoneline (Home PNA)

Powerline

Ultra Wideband (UWB)—for home multimedia delivery.
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Network Security Issues

Unauthorized access and unauthorized use.
 Hacking
 War driving

Protecting against unauthorized access and use.
 Possessed knowledge systems (e.g. passwords).
 Possessed object systems (e.g. cards or badges).
 Biometric systems (e.g fingerprint scanners or
face readers).
 Firewalls and other protective software.
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Network Security Issues, Cont’d.

Computer sabotage

Computer viruses and other types of malware
(e.g. computer worms and Trojan horses).

Denial of service (DoS) attacks.

Malicious spamming.

Data or program alteration.
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Network Security Issues, Cont’d.

Protecting against computer sabotage.

Use up-to-date antivirus and firewall software.

Limit sharing disks and other removable storage media.

Only download programs from reputable Web sites.


Only open e-mail attachments that aren’t executable and are
from people you know.
Regularly download and install the latest security patches
available for your e-mail program and browser.
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Summary

Networking and communications applications

What is a network and how does it transmit data?

Types of networks

Networking hardware

Communications protocols

Network security issues
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