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Chapter 6. Telecommunications and Networks. Learning Objectives. Understand the concept of a network. Apply Metcalfe’s law in understanding the value of a network.
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Chapter 6 Telecommunications and Networks
Learning Objectives • Understand the concept of a network. • Apply Metcalfe’s law in understanding the value of a network. • Identify several major developments and trends in the industries, technologies, and business applications of telecommunications and Internet technologies. • Provide examples of the business value of Internet, intranet, and extranet applications.
Learning Objectives • Identify the basic components, functions, and types of telecommunications networks used in business. • Explain the functions of major components of telecommunications network hardware, software, media, and services. • Explain the concept of client/server networking. • Understand the two forms of peer-to-peer networking. • Explain the difference between digital and analog signals.
Learning Objectives • Identify the various transmission media and topologies used in telecommunications networks. • Understand the fundamentals of wireless network technologies. • Explain the concepts behind TCP/IP. • Understand the seven layers of the OSI network model.
Network Concepts • Network • An 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
Metcalfe’s Law • The usefulness of a network equals the square of the number of users • On a small network, a change in technology affects technology only • On a large network like the Internet, a change in technology affects social, political and economic systems
Telecommunications • Telecommunications • Exchange of information in any form (voice, data, text, images, audio, video) over networks
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
Middleware • Any programming that serves to “glue together” two separate programs
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
Internet2 • Next generation of the Internet • High-performance network • In use at 200 universities, scientific institutions, communications corporations
The Internet • Over 46 million servers (2004) • 710 – 945 million users (2004) • No central computer system • No governing body • No one owns it
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
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
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
Telecommunications network • Any arrangement where a sender transmits a message to a receiver over a channel consisting of some type of medium
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 types • Telecommunications Control Software: programs that control telecommunications activities
Wide Area Network (WAN) • Telecommunications network that covers a large geographic area Source: Courtesy of Cisco Systems Inc.
Local Area Network (LAN) • Connect computers within a limited physical area such as an office, classroom, or building
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
Client/Server networks • Clients: End user personal computers or networked computers • Interconnected by LANs • Servers: manage networks • Processing shared between clients and servers
Network Computing • Networks are the central computing resource of the organization • Thin clients: network computers and other clients provide a browser-based user interface
Peer-to-peer networks • Networks that connect from one PC to another PC • Common use is the downloading and trading of files
Telecommunications Media • Twisted-pair wire: • Ordinary telephone wire • Copper wire twisted into pairs Source: Phil Degginger/Getty Images.
Telecommunications Media • Coaxial cable: • Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Source: Ryan McVay/Getty Images.
Telecommunications Media • Fiber-optic cable: • One or more hair-thin filaments of glass fiber wrapped in a protective jacket Source: CMCD/Getty Images.
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
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
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
Wireless Web • Connect portable communications devices to the Internet
Telecommunications Processors • Modems • Convert digital signals from a computer into • Analog frequencies that can be transmitted over ordinary telephone lines
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
Telecommunications Processors • Multiplexer • Allows a single communications channel to carry simultaneous data transmissions from many terminals
Telecommunications Software • Used by servers and other computers to manage network performance • Network Operating Systems • Middleware
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
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