Transcript Intro to Information Systems

Chapter 6
Telecommunications and
Networks
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 highspeed 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
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