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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