Download Chapter 6 Computers in Your Future Template

Chapter
6
Module 6A
Telecommunications
Module 6B
Networks
Chapter
6
Telecommunications
Understanding the Telephone System
A
6  Modems: From Digital to Analog & Back
 Digital Telephony: Living with Twisted Pair
 Alternatives to Digital Telephony
 Convergence: Is It a Phone or a Computer?
Module

Understanding the
Telephone System
Module
A
6
Public switched
telephone network
(PSTN)
analog system based on standards that date
back more than a century
Learn more about the PSTN and fast-breaking new
telecommunications technologies? PhoneZone.com’s tutorials.
Understanding the
Telephone System
Module
A
6
Quality of Service (QoS)
 Local Exchange Carriers (LECs)

local access & transport area (LATA)
twisted pair
local loop
Fiber Optics Online is a trade journal specializing in fiber
optics industry; this is a great site to learn about new
technologies.
Long-Distance
Transmission Media
If you place a call outside the local transport area, an
interchange carrier (IXC)—a long-distance telephone
Module
company—comes into play
A
6

Transmission facilities
 copper wire
 fiber-optic cables
 microwaves
 satellites
Fiber optic cables consist of thin strands of glass that transmit
data by means of pulses of light.
Standards and Regulations

Standards
International Telecommunications Union (ITU)
Module
A
6  Universal service
Common carrier immunity
 Deregulation

Regional Bell Operating Companies (RBOCs)
The home page of Pacific Bell, a RBOC, is packed with
information and tutorials about cutting-edge
telecommunications services.
More Ways to Access
the System
Module
A
6
Private Branch Exchange (PBX)
 Cellular telephones
 Leased lines

Cellular telephones enable subscribers
to place calls via a wireless
communications system.
The PSTN in Perspective
Module
A
6
Sender of call
receiver of call
As a caller moves from one area to another, a new cell site steps in to keep
the signal strong. The sites are connected to a Mobile Telephone Switching
Office (MTSO), which is connected to the standard PSTN telephone system.
Modems: From Digital to
Analog & Back
Telephone lines use analog receiver
transmission
Module
sender
A
6
Modem 2
Modem 1

How modems work
modulation
demodulation
internal modem
external modem
A modem transforms the computer's
digital signals into analog tones that
can be conveyed through the telephone
system.
Modems: From Digital to
Analog & Back
Module

Asynchronous Communication
asynchronous: used by modems
synchronous
A
6

Modulation Protocols
data transfer rate
bits per second (bps)
V.90 maximum rate of 56 Kbps
V.34 maximum rate of 28800 bps
fall back
Fax
Module
A
6
Facsimile transmission enables you to send an
image of a document over the telephone lines
to anyone who has a fax machine. If your
computer has a fax modem, you can send and
receive faxes from your computer.
Digital Telephony: Living
with Twisted Pair
Module 
Bandwidth
measured in Kbps, Mbps, or Gbps
A
6

Last mile technologies
Integrated Services Digital Network (ISDN)
Digital Subscriber Line (DSL)
Synchronous Optical Network (SONET)
BellSouth is one of the first RBOCs to offer ADSL service.
Follow the links to FastAccess to learn more.
Alternatives to Digital
Telephony
Module
A
6
Direct Broadcast
Satellite (DBS)
 Cable Modems

coaxial cable

Electrical Power
Systems
In contrast to twisted pair, it’s easy to achieve very high
bandwidth data communication with coaxial cable.
Convergence: Is It a Phone
or a Computer
Digitization enables
A convergence, a process
6
of technological
“morphing” in which
previously distinct
devices lose their
sharply-defined
boundaries, and blend
together.
Module
Convergence: Is It a Phone
or a Computer?
Module
A
6
The everything PC
 TV Internet set-tops
 Personal Communication Service (PCS)
 Internet telephony
 Internet faxing

WebTV allows you to access the Internet using your television set
as a display. Visit their web site for more information.
Networks
Module
B
6
Introducing Computer Networks
 Network Fundamentals
 Local Area Networks (LANs)
 Wide Area Networks (WANs)

Introducing Computer
Networks: Synergy at Work

Module 
B
What is a computer network?
Types of computer networks: LANs & WANs
local area network
metropolitan area network
wide area network
6

Networking synergies in a nutshell
reducing hardware costs
enabling shared applications
building massive information resources
connecting people
Introducing Computer
Networks: Synergy at Work
Module
B
6
Computer networks
enable users to share
software and to create
common pools of data.
Network Fundamentals
Module
B
6
 Physical
media
 Switching & routing techniques
circuit switching
packet switching
which is best
Network Fundamentals

Module
B
6

Protocols
proprietary
protocols
open protocols
protocol suite
protocol
layers
Network layers
the protocol stack
A message starts at the "top" of a stack of layers and moves
down through the various layers (protocol stack) until it reaches
the "bottom" or physical media.
Local Area Networks
(LANs): Limited Reach, Fast
Connections
Keyboard &
monitor for
server
Module
B
6
Computer 2
Accounting
Computer 3 Computer 4
Personnel Server - Daily sales
Computer 1
Sales & marketing
Laser
printer
LANs transform an organization's hardware into what
seems to users like one gigantic computer system.
Local Area Networks
(LANs): Limited Reach, Fast
Connections
Module 
B
6
Networking hardware: Network Interface
Cards (NICs)
workstation
node

Networking software
peer-to-peer networks
client/server networks

Clients
Local Area Networks
(LANs): Limited Reach, Fast
Connections
Module

Media
twisted pair
coaxial cable
fiber-optic cable
infrared
radio
B
6

LAN topologies
bus (daisy chain)
star
ring
Local Area Networks
(LANs): Limited Reach, Fast
Connections
Module
B
6
Most networks use a bus, star, or ring topology.
LAN Technologies
Module
B
6
By far the most popular
LAN standard is
Ethernet
Like to know the latest news about LANs? Check out LAN
Times, the premiere LAN trade journal
Like to learn more about the Ethernet? Check out Charles
Spurgeon’s Ethernet Web Site which covers all the Ethernet
technologies used today and includes a practical guide for do-ityourselfers.
LAN Protocals
AppleTalk
 IPX/SPX
 NetBEUI
 TCP/IP

Module
B
6
Like AppleTalk, TCP/IP can be used with a variety of lowerlevel protocols, such as Ethernet. A LAN that uses TCP/IP is
called an intranet, a term that suggests that it’s an Internet
designed for internal use within an organization.
Wide Area Networks (WANs):
Long-Haul Carriers
WANs are like long-distance telephone systems
Module
B
6
 How
WANs work
Point of Presence (POP)
backbones
The Internet is a WAN of massive
proportions. Backbone provider
UUNET offers local access from
more than 1,000 locations
worldwide.
Wide Area Networks (WANs):
Long-Haul Carriers

public data network (PDN)
virtual private network (VPN)
Module
B
6
How WANs are organized

WAN protocals
oldest is X.25

WAN Applications
LAN-LAN connections
transaction acquisition
electronic data interchange (EDI)
To explore cutting-edge WAN technologies such as SDMS
and ATM, a good place to start is Pacific Bell’s FasTrak
Data and Video Services page