Chapter 6

Telecommunications and Networks

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Learning Objectives

1. Understand the concept of a network.

2. Apply Metcalfe’s law in understanding the value of a network.

3. Identify several major developments and trends in the industries, technologies, and business applications of telecommunications and Internet technologies.

4. Provide examples of the business value of Internet, intranet, and extranet applications.

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Learning Objectives

5. Identify the basic components, functions, and types of telecommunications networks used in business.

6. Explain the functions of major components of telecommunications network hardware, software, media, and services.

7. Explain the concept of client/server networking.

8. Understand the two forms of peer-to-peer networking.

9. Explain the difference between digital and analog signals.

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Learning Objectives

10.Identify the various transmission media and topologies used in telecommunications networks.

11.Understand the fundamentals of wireless network technologies.

12.Explain the concepts behind TCP/IP.

13.Understand the seven layers of the OSI network model.

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Network Concepts

• Network– An interconnected chain, group or system

• Number of possible connections on a network is N * (N-1) / 2– Where N = number of nodes (points of connections on

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

are 10 * 9 / 2 = 45 possible connections

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Trends in Telecommunications

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Digital Network Technologies

• Rapid change from analog to digital network technologies

• Analog: voice-oriented transmission, sound waves• Digital: discrete pulse transmission• Digital allows:

– Higher transmission speed– Larger amounts of information– Greater economy– Lower error rates– Multiple forms of communications on same circuit

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Internet2

• Next generation of the Internet• High-performance network• In use at several hundred universities, scientific

institutions, communications corporations

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Business Value of Telecommunication Networks

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The Internet

• 2.27 billion users (2012)• No central computer system• No governing body• No one owns it

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Internet Service Provider

• ISP– A company that specializes in providing easy access to

the Internet– For a monthly fee, you get software, user name,

password and access

• ISPs are connect to one another through network access points

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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 organization– That 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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Extranet

• Network links that use Internet technologies– To connect the Intranet of a business– With the Intranets of its customers, suppliers or other

business partners

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Extranet Uses

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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 LANs

• Servers: manage networks

• Processing 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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Peer-to-Peer Network

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Telecommunications Media

• Twisted-pair wire:– Ordinary telephone wire– Copper 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 microwave– Earthbound microwave systems that transmit high-

speed radio signals in a line-of-sight path– Between relay systems spaced approximately 30-miles

apart

• Communications 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 systems– Divide the geographic area into small areas or cells– Each cell has transmitter or radio relay antenna to send

message from one cell to another

• Wireless LANs– Radio signals within an office or building– Connect PCs to networks

• Bluetooth– Short-range wireless technology– To connect PC to peripherals such as printer

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Wireless Web

• Connect portable communications devices to the Internet

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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

• Multiplexer - Allows a single communications channel to carry simultaneous data transmissions from many terminals

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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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Network Architectures & Protocols

• Protocol: standard set of rules and procedures for the control of communications in a network

• Transmission Control Protocol / Internet Protocol (TCP/IP)– A five layer telecommunications protocol used by the

Internet

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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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View How the Internet Works Video