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2002
Sharing Information and Resources
Through Networks
2002
TELECOMMUNICATIONS
Communicating Information
Via Electronic Means
Over Some Distance• Next Office
• Next Continent
*
2002
Atlanta
Chicago
MIS
Accounting
2002
PROTOCOL
Rules & Procedures
To Govern Transmission
Between Components
In A Network
-TCP/IP
-OSI
2002
ANALOG SIGNAL
• Continuous Waveform
• Passes Through System
• Voice Communications
*
2002
DIGITAL SIGNAL
• Discrete Waveform
• Two Discrete States:– 1-bit & 0-bit– On / Off Pulse
• Data Communication
*
2002
Modems
• Convert Digital data (computers) to Analog signal(voice)– Internal/ External
2002
Multiplexer / Concentrator
• Combines signals from several terminals to be carried over one communications channel
• High-speed line
• Frequency
• Time
2002
COMMUNICATION CHANNELS
Means By Which Data Are Transmitted:
• Twisted Pair (Copper Wires)
• Coaxial Cable: (Insulated Copper Wires)
• Fiber-optic Cable
• Wireless
2002
COMMUNICATIONS CHANNELS
• TRANSMISSION SPEED: Bits per Second (BPS) or Baud
• BANDWIDTH: Capacity of Channel; Difference between Highest & Lowest Frequencies– Baseband (voice) - single transmission only– Broadband - divides channel by time or
frequency for several transmissions at once
2002
Twisted Pair
• UTP - Unshielded Twisted Pair– Cat 3 ~ 10Mbps, Cat 5 ~ 100Mbps
• Copper Wire; electrical signal
• Baseband
• Analog or Digital signal
• Crosstalk
• Low cost, easy to install
2002
Coaxial Cable
• Shielded Copper Wire; electrical signal
• Faster, less noise
• Baseband and Broadband
• Not flexible
• More noise resistant
*
2002
FIBER OPTICS
• Super Clear Glass or Plastic Fiber Strands
• Laser generates light signal
• Difficult to tap
• Up To Ten Billion Bits Per Second
• Full Duplex, Broadband
*
SIGNALSIGNAL LASERLASER CABLECABLE PHOTOPHOTODETECTORDETECTOR SIGNALSIGNAL
2002
Wireless Transmission
• Microwave
• Satellite
• Cellular and PCS
• Infrared Light
2002
Radio Waves
• Line of sight
• Antenna to Antenna
• Save $ because don’t run cable
• Interference or Security concerns
• Good if mobile
• 1-10 MBPS
• WAP – Wireless Application Protocol
2002
SPEEDS & COST OF MEDIA MEDIUMMEDIUM SPEEDSPEED COSTCOST
TWISTED PAIRTWISTED PAIR 300 BPS - 10 MBPS300 BPS - 10 MBPS LOWLOW
MICROWAVEMICROWAVE 256 KBPS - 100 MBPS256 KBPS - 100 MBPS
SATELLITESATELLITE 256 KBPS - 100 MBPS256 KBPS - 100 MBPS
COAXIAL CABLECOAXIAL CABLE 56 KBPS - 200 MBPS56 KBPS - 200 MBPS
FIBER OPTICSFIBER OPTICS 56 KBPS - 10 GBPS56 KBPS - 10 GBPS HIGHHIGH BPS: BITS PER SECONDBPS: BITS PER SECOND KBPS: KILOBITS PER SECONDKBPS: KILOBITS PER SECOND MBPS: MEGABITS PER SECONDMBPS: MEGABITS PER SECOND GBPS: GIGABITS PER SECONDGBPS: GIGABITS PER SECOND
2002
Client/Server Networks
• Server - Stores Programs, Data; Determines Access to Network … for many users.
• Client - Desktop interface– Fat client - client has power on desktop to run
programs (PC)– Thin Client - all deployed from server
• Less $ to support• Always current• One interface, Training easier
2002
Computer Networks
Arts & SciencesLAN
RussLAN
Rike LANLAN
L1
L2L3
L4
Lake CampusLANs
WANInternet
WSU
Bac
kbon
e
2002
NETWORK TOPOLOGIES
HOSTHOST
USERUSER
USERUSER
USERUSER USERUSER
STAR
2002
NETWORK TOPOLOGIES
BUS
USERUSER
USERUSER
SServererver
PrinterPrinter
USERUSER
USERUSER
2002
NETWORK TOPOLOGIES
USERUSER
USERUSER
USERUSER
USERUSER
RING
2002
LOCAL NETWORKS
• LOCAL AREA NETWORK (LAN): – Limited Distance (less than 2000 foot radius)
– Can Share Expensive Hardware & Software• Printers
• Office Products
*
2002
Local Area NetworksServer based Network Peer-to-peer Network
SERVER
PC PC PC PC
PC PC PC
Client Client Client
Client Client
2002
Metropolitan Area Network
• Often called a MAN
• Within a Local Dialing Area
• Often within a city
• Uses a Common Carrier’s Lines
• Often divisions of same company that are not in close proximity to set up a LAN
2002
• Spread over a large geographical area
• Common Carrier– Pay for usage and share ‘lines’
– Telephone Lines– Fiber Optic Cables
– Microwaves– Satellites
Wide Area Networks
2002
Wide Area Network - Connection
• Switched or Dial-up– Temporary connection
• Dedicated or Leased Lines– 2 locations (private)– High volume user– Always available
• Value Added Network– 3rd party leased lines
2002
VALUE-ADDED NETWORK (VAN)
• Private; Multipath; Data Only
• 3rd Party Managed
• Used By Several Organizations
• Subscription Basis– Fee + Usage
*
2002
PACKET SWITCHING
• Breaks Data Blocks Into Small Packets (E.G.: 128 Bytes)
• Packets Routed By Most Economical Means
• Reassembled At Destination
• Used on Value Added Networks
*
2002
Wide Area NetworksSending Data on the Internet
DestinationComputer
ISP
Router
Router
RouterPackets
Packets
Packets
Packets
Packets
User’s PC
Packets
2002
Uses of Telecommunications
• Telecommuting
• Electronic Mail
• On-Line Information Services
• Teleconferencing
• Facsimile Transmissions
• Electronic Data Interchange AOL
CompuServe
MSN
2002
Electronic Data Interchange
• Computer to Computer exchange of business transactions– Orders– Bills
• Save $ and time
• Eliminate errors by entered only once
• EFT - Electronic Funds Transfer
2002
• Group Writing & Commenting
• Electronic Mail Distribution
• Scheduling Meetings
• Shared Files & Databases
• Electronic Meetings
*
GroupWare
2002
Teleconferencing
• Electronic meetings
• Less travel
• More can attend
• Less cost
• Videoconference
• Computer conference
2002
Wide Area Networks
ISP Link to the Internet
ISP
Parent’sPC
Regional Network Regional Network
Internet Backbone
College LAN
Student’s PC
2002
Connection Options• Cable - 4/10 Mbps, ~$40/mo (digital)
– Ethernet Card and Cable Modem+ ($200-300)
• DSL - 8 Mbps, ~$30-150/mo (digital)
– DSL Hub + Ethernet Card, Dedicated(3)
• T-1 Line -1.5 Mbps,~$1,000s,Dedicated, Digital
– (T-2~6.3Mbps; T-3~44Mbps; T-4~275Mbps)
• ISDN - 128 Kbps, $56-82/mo– Digital Service Unit+ ($200-300), Dial-up
• Phone-line modem - 56Kbps, ~$20/mo– Modem < $50, Dial-up, Analog
2002
The Internet
• Server address
• Domain name
• E-mail address
A Network of Networks
sales @ fareastfoods.com
Username
Server address
2002
The World Wide Web• Client/Server network
• Browser–Netscape
–Internet Explorer
• Hypertext markup language - HTML
2002
The World Wide Web• Web pages• Web site• Multimedia files• URLs
2002
The World Wide Web
• Default HTML file (Home)
• Electronic commerce
• Intranets
• Extranets
2002
INTRANET
• Internal Network• WWW Technology• Firewall: Security System to Prevent Invasion of
Private Networks• Need Password• Overcomes Computer Platform Differences• Often Installed On Existing Network
Infrastructure*
2002
EXTRANET
Private Internet Accessible To Select Outsiders - Need Password
Link Organization To
• Important Clients
• Business Partners
• Top Executives & Board Members*
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