Transcript Networks

Discovering Computers 2008
Chapter 9
Communications
and Networks
Communications
-- Telecommunications
What are computer communications?

Process in which two or more computers or devices transfer data,
instructions, and information
notebook
computers
smart
phones
servers
Web-enabled
PDAs
GPS
receivers
desktop
computers
mainframe
computers
Tablet PCs
p. 460 Fig. 9-1
Blackberry Video
Next
Networks – Local Area Network
What is a local area
network (LAN)?

Network in limited
geographical area such
as home or office
building

p. 471 Fig. 9-10
Metropolitan area
network (MAN)
connects LANs in city
or town
Next
Communication Devices -- Hardware
Requirements
 Sending Device

Initiates Instruction to Transmit
 Communications Device

Connects Sending Device to Channel

Connects Channel to Receiving Device
 Communications Channel or Transmission Media

Media on Which Data Travels
 Receiving Device

p. 460
Accepts Transmission
Communications Devices
What are examples of communications devices?
Common types are dial-up modems, ISDN and
DSL modems, cable modems, network cards,
wireless access points, routers, and hubs
ISDN and DSL modems send
and receive data from ISDN
and DSL lines
p. 482
Next
Communications Channel also known as
Transmission Media
What are examples of transmission media?
Transfer Rates for Various Types of LANs Using Physical Transmission Media

Wire, cable,
and other
tangible
materials used
to send
communications
signals
p. 490 Fig. 9-35
Next
Wireless Transmission Media
What is wireless transmission media?


Used when inconvenient, impractical, or impossible to
install cables
Includes Bluetooth and IrDA
p. 494 Fig. 9-40
Networks
Collection of Computers & Devices
 Connected via

Communications Devices -- Slide 5

Transmission Media – Slide 6
Uses of Computer Communications
What are some uses of communications technology?
Internet
Chat Rooms
FTP
p. 462
Web
Instant
Messaging
E-Mail
Newsgroups
Web
Folders
Internet
Telephony
Video
Conferencing
Fax Machine
or Computer
Fax/Modem
Next
Uses of Computer Communications
What are Wireless Messaging Services?
 Text Messaging

Send / Receive Short Text Messages Using Phone
 Picture Messaging

Send / Receive Graphics, Pictures, Video, Sound
Uses of Computer Communications
What is a global positioning system (GPS)?
Step 1.
GPS satellites orbit
Earth. Every 1/1000
of a second, each
satellite sends a signal
that indicates its
current position to the
GPS receiver.
Click to view Web
Link, click Chapter 9, Click
Web Link from left
navigation, then click
GPS below Chapter 9
p. 466 Fig. 9-6
Step 2.
A GPS receiver
(such as in a car,
a wearable
device, a smart
phone, a
handheld device,
or a collar)
determines its
location on Earth
by analyzing at
least 3 separate
satellite signals
from the 24
satellites in orbit.
Next
Uses of Computer Communications
What is groupware?
 Groupware is software
that allows people
work together and share
information
MS Office 2007: SharePoint
Server: A big share drive to
share files with others at the
college.
SharePoint video
Google Wave
p. 467 Fig. 9-7
Next
Network Types
LAN (Local Area Network)
 Network in Limited Geographical Area

Typically Within a Building
Network Types
What is a wide area
network (WAN)?
 Network that covers
large geographic
area using many
types of media
 Internet is world’s
largest WAN
p. 472 Fig. 9-12
Next
Network Types
What is a client/server
network?
 One or more computers
act as server and other
computers, or clients,
access server
 Clients request
RESOURCES on the
server
p. 472 Fig. 9-13
Next
Networks
What is a site license?
Legal agreement that allows multiple users to run a
software package simultaneously
License fee usually based on number of users or number
of computers attached to network
www.cursorarts.com/ca_price.html
Networks
What are the components
of a client/server network?







File server
Workstation
Network interface card
UPS
Network Operating System
Printers
Backups
p. 472 Fig. 9-12
Next
Network Types
What is a peer-to-peer
network?
 Simple network
that connects
fewer than 10
computers
 Each computer,
or peer, has equal
capabilities
p. 473 Fig. 9-14
Next
Network Types
What is Internet peer-to-peer
(P2P)?
 Sometimes called a file
sharing network
 Enables users to
connect to each other’s
hard disks and
exchange files directly
Click to view Web
Link, click Chapter 9, Click
Web Link from left
navigation, then click
BitTorrent below Chapter 9
p. 473 - 474 Fig. 9-15
Next
Criticism
 Illegal music/video sharing
 Kazaa
 Napster
 The Pirate Bay
 Strain on ISP
 Bandwidth supply <
Bandwidth demand
Network Topology
Layout of devices in a network
Popular types of topology
Bus
Ring
Star
Bus Topology
What is a bus network?

All computers and
devices connect to
central cable,
or bus
Star Topology
What is a star network?

All devices connect to
a central device, called
hub

All data transferred
from one computer to
another passes
through hub
p. 475 Fig. 9-17
Next
Networks
What is a ring network?

Cable forms closed
ring, or loop, with all
computers and devices
arranged along ring

Data travels from
device to device
around entire ring, in
one direction
p. 474 Fig. 9-16
Next
Networks
What is an intranet?
Internal network that uses Internet technologies
Makes information accessible to employees
Typically includes connection to Internet
Don’t confuse and intranet with:
Extranet allows customers or suppliers to access
part of company’s intranet
p. 475
Next
Networks
What is an extranet?
Allows customers or suppliers
outside of the company to
access part of company’s
intranet
Customer checking
package on Fed Ex’s
intranet via the Internet
Bus Topology
What is a bus network?

All computers and
devices connect to
central cable,
or bus
Protocol & Standards -- Wired
Ethernet
How Ethernet Cards Work
 For LANs
 Uses Bus or Star Topology
 One of Most Widely Implemented Standards
Protocol & Standards -- Wired
TCP/IP-- Transmission Control Protocol/Internet Protocol
 Commonly Used for Internet Transmissions
 Packet Switching

Transmits Data by Breaking it Into Packets
 Reassembles Data at Destination
TCP/IP Animation
Network Communications Standards
Wi-Fi identifies any
network based on the
802.11 standard that
facilitates wireless
communication
Sometimes referred to as
wireless Ethernet
Compare speeds:
802.11n vs. 802.11g
30
How to Setup a Wireless Network
http://www.youtube.com/watch?v=hlvYyWbzVa0
Network Communications Standards
Bluetooth limited to:
10 meters = 33 ft. TO
100 meters = 330 ft.
Short-range Radio Technology
IrDA
Data Transferred via Infrared Light Waves
p. 477 - 478 Fig. 9-20
Next
Protocols & Standards
RFID -- Radio Frequency Identification – replace bar code reader
 Uses Radio Signals

Communicates with Tag Placed in Object
 Legislation

Nevada
– Require Retailers to Inform Customers Product is Tagged

Rhode Island
– No Government Agency can Use to Track Individuals

TX
– Prohibit Schools from Using RFID on Students
How RFID Works
RFID and Sushi
Network Communications Standards
Communications Over the Telephone Network
What is a dial-up line?

Temporary connection using telephone line for communications


Costs no more than making regular call
Computers at any two locations can establish a connection using
modems and telephone network
Communications Over the Telephone Network
The Telephone Network
What is transfer rate?
Speed at which a line carries data and information
Faster the transfer rate, the faster you can send and receive data and
information
Usually expressed as a measure of bits per second
bits per second
(bps)
kilobits per second
(Kbps)
megabits per second
(Mbps)
gigabits per second
(Gbps)
Communications Over the Telephone Network
What is a dedicated line?
 Always-on connection
between two
communications
devices




ISDN
DSL
T-carrier line
ATM -- Asynchronous
Transfer Mode
p. 482 Fig. 9-24
Next
Communications Devices --Wired
What are ISDN and DSL modems?
Communications devices that send and
receive digital ISDN and DSL signals
Usually external devices in which one
end connects to a telephone line and the other
end connects to a port on the system unit
p. 485
Next
Communications Devices
What is a cable modem?
 Sends and receives
data over cable
television network
 Much faster than
dial-up modem or
ISDN
 Sometimes called a
broadband modem
Click to view Web
Link, click Chapter 9, Click
Web Link from left
navigation, then click
Cable Modems
below Chapter 9
p. 485 - 486 Fig. 9-28
Next
Cable Modem vs. DSL
Video –Cable & DSL
Cable Modem
Advantage:
Widespread Availability
Disadvantage:
Competition with shared users
DSL
Advantage:
Not shared with other users
Disadvantage:
Radius of user and service limited
Communications Over the Telephone Network
What is an ADSL (asymmetric digital subscriber line)?


Popular type of
DSL (Digital
Subscriber Line)
Faster when
receiving data
than when
sending data

Ideal for Internet
access
Next
Communications Devices
A network card enables
a computer or device
to access a network
Available in a variety of
styles
Wireless network cards
often have an
antenna
same waves used by cell phones
Communications Devices
A router connects
multiple computers
or other routers
together and
transmits data to its
correct destination on
a network
Many are protected by a
hardware firewall
Fastest path available
Communications Devices
A hub or switch connects several devices in a network
together
What's the difference between a hub and a
router?
A hub just allows several network cables to be attached,
putting several computers on the same network.
A router has a processor that allows it to decide where to send
traffic, and possibly to modify the details.
A hub glues together an Ethernet network segment
A router can do those functions plus route TCP/IP packets
between multiple PCs on LAN and a WAN
Some hubs include routers
Home Networks
What is a home network?
 Multiple computers
connected in home
 Several types of wired
home networks



Ethernet — connect
computers via cable
Powerline cable —
use electrical lines in house
Phoneline — use
telephone lines
Click to view Web
Link, click Chapter 9, Click
Web Link from left
navigation, then click
Home Networks
below Chapter 9
p. 489 - 490 Fig. 9-34
Next
Communications Channel
What is a communications channel?
 Transmission media on which data travels in
communications system – both wired and wireless
Transmission media
are materials capable of
carrying one or more
signals
p. 491
Bandwidth is amount of
data that can travel
over a communications
channel
Next
What is physical transmission media?
p. 492 Fig. 9-36
Physical Transmission Media
What are twisted-pair cable and coaxial cable?


Twisted-pair cable is used for telephone systems and network cabling
Coaxial cable is often used for cable television wiring
p. 493 Fig. 9-37—9-38
Next
Physical Transmission Media
What is fiber-optic cable?
 Capable of carrying
significantly more
data at faster speeds
than wire cables
 Less susceptible
to interference
(noise) and, therefore,
more secure
 Smaller size (thinner
and lighter)
4/9/09 Fiber Optic Cable Security?
p. 493 Fig. 9-39
Next
Wireless Transmission Media
What is wireless transmission media?


Used when inconvenient, impractical, or impossible to
install cables
Includes Bluetooth and IrDA
p. 494 Fig. 9-40
Wireless Transmission Media
Microwave Station
 Earth-based Reflective Dish

Contains Antenna, Transceivers
 Uses Line-of-sight Transmission
Universities, hospitals,
government, cable television
–straight line with no
obstructions
Wireless Transmission Media
Satellite
 Space Station

Receives Microwave Signals

Broadcasts Signals Back to Earth-based Stations
TV, GPS, air navigation