6-1McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

Telecommunications and Networks

Business value of networksThe Internet

Network components

Chapter

6

McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

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Network Concepts

NetworkAn interconnected chain, group or system

Number of possible connections on a network is N * (N-1)Where N = number of nodes (points of

connections on the network)Example, if there are 10 computers on a

network, there are 10 * 9 = 90 possible connections

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Telecommunications

TelecommunicationsExchange of information in any form (voice,

data, text, images, audio, video) over networks

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Trends in Telecommunications

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Open Systems

Information systems that use common standards for hardware, software, applications and networks

Internet networking technologies are a common standard for open systems

Connectivity: Ability of networked computers to easily access and

communicate with each other and share information Interoperability:

The ability of an open system to enable end user applications to be accomplished using different varieties of computer systems, software packages, and databases provided by a variety of interconnected networks

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Middleware

Any programming that serves to “glue together” two separate programs

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Digital Network Technologies

Rapid change from analog to digital network technologies

Analog: voice-oriented transmission, sound waves

Digital: discrete pulse transmissionDigital allows:

Higher transmission speedLarger amounts of informationGreater economyLower error ratesMultiple forms of communications on same circuit

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Internet2

Next generation of the InternetHigh-performance networkIn use at 200 universities, scientific

institutions, communications corporations

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Business Value of Telecommunication Networks

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The Internet

Over 46 million servers (2004)710 – 945 million users (2004)No central computer systemNo governing bodyNo one owns it

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Internet Service Provider

ISPA company that specializes in providing easy

access to the InternetFor a monthly fee, you get software, user name,

password and accessISPs are connect to one another through

network access points

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Popular uses of the Internet

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Using the Internet for business

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Business value of the Internet

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An Intranet

A network inside an organizationThat uses Internet technologies (such as Web

browsers and servers, TCP/IP protocols, HTML, etc.)

To provide an Internet-like environment within the organization

For information sharing, communications, collaboration and support of business processes

Protected by security measures Can be accessed by authorized users through

the Internet

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Enterprise Information Portal

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Extranet

Network links that use Internet technologiesTo connect the Intranet of a businessWith the Intranets of its customers, suppliers or

other business partners

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Extranet Uses

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Telecommunications network

Any arrangement where a sender transmits a message to a receiver over a channel consisting of some type of medium

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Telecommunications network components

Terminals: any input/output device that uses networks to transmit or receive data

Telecommunications Processors: devices that support data transmission and reception

Telecommunications Channels: media over which data are transmitted and received

Computers: all sizes and typesTelecommunications Control Software:

programs that control telecommunications activities

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Telecommunications network model

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Wide Area Network (WAN)

Telecommunications network that covers a large geographic area

Source: Courtesy of Cisco Systems Inc.

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Local Area Network (LAN)

Connect computers within a limited physical area such as an office, classroom, or building

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Virtual Private Networks (VPN)

A secure network that uses the Internet as its backbone but relies on firewalls, encryption and other security

A pipe traveling through the Internet

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VPN

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Client/Server networks

Clients: End user personal computers or networked computers

Interconnected by LANsServers: manage networksProcessing shared between clients and

servers

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Client/Server Network

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Network Computing

Networks are the central computing resource of the organization

Thin clients: network computers and other clients provide a browser-based user interface

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Peer-to-peer networks

Networks that connect from one PC to another PC

Common use is the downloading and trading of files

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Telecommunications Media

Twisted-pair wire:Ordinary telephone

wireCopper wire

twisted into pairs

Source: Phil Degginger/Getty Images.

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Telecommunications Media

Coaxial cable:Sturdy copper or

aluminum wire wrapped with spacers to insulate and protect it

Source: Ryan McVay/Getty Images.

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Telecommunications Media

Fiber-optic cable:One or more hair-

thin filaments of glass fiber wrapped in a protective jacket

Source: CMCD/Getty Images.

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Problem of “The Last Mile”

Network providers use fiber optic to provide backbone

But houses are connected to the backbone via twisted-pair

Cannot get the benefit of the faster, better technology

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Wireless Technologies

Terrestrial microwaveEarthbound microwave systems that transmit

high-speed radio signals in a line-of-sight pathBetween relay systems spaced approximately

30-miles apartCommunications satellites

Satellite serves as relay stations for communications signals

Uses microwave radio signals

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Wireless Technologies

Cellular and PCS telephone and pager systemsDivide the geographic area into small areas or

cellsEach cell has transmitter or radio relay antenna

to send message from one cell to anotherWireless LANs

Radio signals within an office or buildingConnect PCs to networks

BluetoothShort-range wireless technologyTo connect PC to peripherals such as printer

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Wireless Web

Connect portable communications devices to the Internet

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Telecommunications Processors

ModemsConvert digital signals from a computer into Analog frequencies that can be transmitted over

ordinary telephone lines

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Internetwork Processors

Switch – makes connections between telecommunications circuits in a network

Router – intelligent communications processor that interconnects networks based on different protocols

Hub – a port switching communications processor

Gateway – connects networks using different communications architectures

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Telecommunications Processors

MultiplexerAllows a single communications channel to carry

simultaneous data transmissions from many terminals

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Telecommunications Software

Used by servers and other computers to manage network performance

Network Operating SystemsMiddleware

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Network management functions

Traffic Management – manage network resources and traffic to avoid congestion and optimize service levels to users

Security – provide authentication, encryption, firewall, auditing and enforcement

Network Monitoring – troubleshoot and watch over the network, informing network administrators of potential problems before they occur

Capacity Planning – survey network resources and traffic patterns and users’ needs to determine how best to accommodate the needs of the network as it grows and changes

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Network Topologies

Topology: structure of a network

Star: ties end user computers to a central computer

Ring: ties local computer processors together in a ring on a relatively equal basis

Bus: local processors share the same communications channel

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Network Topologies

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Internet Telephony

Using an Internet connection to pass voice data using IP

Voice over IP (VoIP)Skips standard long-distance phone charges

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Bandwidth

BandwidthFrequency range of a telecommunications

channelDetermines transmission rateClassified in bits per second (bps)

Transmission Rates:Narrow-band – low-speedBroadband – high-speed

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Transmission Speeds

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Network Interoperability

Ensure that anyone anywhere on one networkCan communicateWith anyone anywhere on another network

Telecommunications as discussed in this chapter wouldn’t be possible without interoperability