Understanding Computers Ch.81 Chapter 8 Computer Networks.

Understanding Computers Ch.8 1

Chapter 8

Computer Networks


Learning Objectives

Describe several uses for communications technology.

Understand characteristics about data and how it travels over a network.

Name specific types of wired and wireless transmission media and explain how they transmit messages from one device to another.


Learning Objectives, Cont’d.

Explain the difference between local area, wide area, and other types of networks.

List several types of networking hardware and explain the purpose of each.

Identify the different protocols that can be used to connect the devices on a network.

Discuss some security issues involved with computer network usage and some security precautions that can be taken.


Overview

This chapter covers: Common networking and communications applications

The concepts and terminology involved with computer networks

Common types of networks and the hardware and software involved in a computer network

Various communications protocols that can be used

Network security issues


Networking and Communications Applications

Wireless phones Cellular phones Satellite phones

Paging and messaging

Global positioning systems (GPSs)

Satellite radio


Networking and Communications Applications, Cont’d.

Online conferencing (online meetings) Videoconferencing Web conferencing

Collaborative computing

Telecommuting

Telemedicine


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.


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.


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).


Data Transmission Characteristics, Cont’d.

Transmission timing

Synchronous transmission

Asynchronous transmission

Isochronous transmission


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).


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.



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.



Network Topologies

Star

Bus

Ring

Combination


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.


LANs, WANs, and Other Types of Networks

Local area networks (LANs)

Wide area networks (WANs)

Metropolitan area networks (MANs)

Personal area networks (PANs)


LANs, WANs, and Other Types of Networks, Cont’d.

Intranets and extranets

Virtual private networks (VPNs)

Storage area networks (SANs)


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.).



Networking Hardware, Cont’d. Modems (used to connect PC to the Internet)

Conventional dial-up

ISDN

DSL

Cable

Satellite


Networking Hardware, Cont’d.

Hubs, switches, and routers

Wireless access points

Gateways and bridges

Repeaters

Multiplexers and concentrators



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.


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.


Token Ring

Usually used with a ring network topology and utilizes a token to send and retrieve data.


TCP/IP

The protocol used with the Internet also increasingly being used with LANs.

Sends data in packets.


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.


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.


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.


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.



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.


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

Understanding Computers Ch.81 Chapter 8 Computer Networks.

Documents

understanding computers

parallel transmission

wireless transmission

wireless network connections

computer network usage

halfduplex transmission

wired network connection

network security issues