Transcript Networks - Drexel University

Sharing Information
and Resources
Through Networks
2002
TELECOMMUNICATIONS
Communicating Information
Via Electronic Means
Over Some Distance
• Next Office
• Next Continent
*
2002
Chicago
Accounting
MIS
Atlanta
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
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2002
DIGITAL SIGNAL
• Discrete Waveform
• Two Discrete States:
– 1-bit & 0-bit
– On / Off Pulse
• Data Communication
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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
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Copper Wire; electrical signal
Baseband
Analog or Digital signal
Crosstalk
Low cost, easy to install
2002
Coaxial Cable
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Shielded Copper Wire; electrical signal
Faster, less noise
Baseband and Broadband
Not flexible
More noise resistant
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2002
FIBER OPTICS
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Super Clear Glass or Plastic Fiber Strands
Laser generates light signal
Difficult to tap
Up To Ten Billion Bits Per Second
Full Duplex, Broadband
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SIGNAL
2002
LASER
CABLE
PHOTO
DETECTOR
SIGNAL
Wireless Transmission
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Microwave
Satellite
Cellular and PCS
Infrared Light
2002
Radio Waves
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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
MEDIUM
TWISTED PAIR
SPEED
300 BPS - 10 MBPS
MICROWAVE
256 KBPS - 100 MBPS
SATELLITE
256 KBPS - 100 MBPS
COAXIAL CABLE
56 KBPS - 200 MBPS
FIBER OPTICS
56 KBPS - 10 GBPS
BPS: BITS PER SECOND
KBPS: KILOBITS PER SECOND
MBPS: MEGABITS PER SECOND
GBPS:
GIGABITS PER SECOND
2002
COST
LOW
HIGH
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
L1
L2
Lake Campus
LANs
L3
WSU Backbone
L4
2002
Arts & Sciences
LAN
Russ
LAN
Rike LAN
LAN
WAN
Internet
NETWORK TOPOLOGIES
USER
USER
HOST
USER
STAR
2002
USER
NETWORK TOPOLOGIES
USER
USER
Printer
USER
USER
Server
BUS
2002
NETWORK TOPOLOGIES
USER
USER
USER
USER
RING
2002
LOCAL NETWORKS
• LOCAL AREA NETWORK (LAN):
– Limited Distance (less than 2000 foot radius)
– Can Share Expensive Hardware & Software
• Printers
• Office Products
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2002
Local Area Networks
Server based Network
Client
Client
2002
Client
S
E
R
V
E
R
Client
Client
Peer-to-peer Network
PC
PC
PC
PC
PC
PC
PC
Metropolitan Area Network
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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
Wide Area Networks
• Spread over a large geographical area
• Common Carrier
– Pay for usage and share ‘lines’
– Telephone Lines
– Fiber Optic Cables
– Microwaves
– Satellites
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)
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Private; Multipath; Data Only
3rd Party Managed
Used By Several Organizations
Subscription Basis
– Fee + Usage
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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
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2002
Wide Area Networks
Sending Data on the Internet
Router
Packets
I
S
P
Packets
Router
User’s PC
Destination
Computer
Packets
Router
Packets
2002
Packets
Packets
Uses of Telecommunications
MSN
AOL
2002
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CompuServe
Telecommuting
Electronic Mail
On-Line Information Services
Teleconferencing
Facsimile Transmissions
Electronic Data Interchange
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
GroupWare
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2002
Group Writing & Commenting
Electronic Mail Distribution
Scheduling Meetings
Shared Files & Databases
Electronic Meetings
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Teleconferencing
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Electronic meetings
Less travel
More can attend
Less cost
Videoconference
Computer conference
2002
Wide Area Networks
ISP Link to the Internet
I
S
P
Regional Network
Regional Network
Internet Backbone
College LAN
2002
Parent’s
PC
Student’s PC
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
A Network of Networks
• Server address
• Domain name
• E-mail address
sales @ fareastfoods.com
2002
User
name
Server address
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
*
2002
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Copyright © 2001
by Harcourt, Inc.
All rights reserved.
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