Chapter 5
Business Networks &
Telecommunications
p189 – 203:
1.VPN
2. Switching
3. Protocols
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Revision:
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What is makes up the Telecommunications
Network Model?
What are the two categories of media?
Name the different media?
What is the difference between a digital and
analog signal?
List the 4 different types of networks?
What type of network is on slide 4?
Telecommunications NW Model:
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A telecommunications network is any
arrangement where
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A sender transmits a message
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To a receiver
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Over a channel
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Consisting of some sort of medium
What type of network?
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Different Media:
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Wired (or …….) and Wireless (…………)
See next slides
Telecommunications Media
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Twisted-Pair Wire
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Ordinary telephone wire
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Copper wire is twisted
into pairs
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Telecommunications Media
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Coaxial Cable
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Sturdy copper or
aluminum wire wrapped
with spacers to insulate
and protect it
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Telecommunications Media
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Fiber-Optic Cable
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One or more hair-thin
filaments of glass
fiber wrapped in a
protective jacket
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Analog versus Digital
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Analog or digital refers to the method used to
convert information into an electrical signal
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Analog: an electrical current is generated that
is proportional to the quantity being observed
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Digital: the quantity being observed is expressed
as a number
Digital Network Technologies
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Telecommunications are being revolutionized
by switch from analog to digital
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Analog: voice-oriented transmission
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Digital: discrete pulse transmission
Benefits
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Higher transmission speeds
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Moves larger amounts of information
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Greater economy and much lower error rates
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Transmits multiple types of communications (data, voice,
video) on the same circuits
Virtual Private Network:
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A network is private, when only authorized
users can access the network.
So instead leasing lines and services from an
ISP, a company can use the internet by
isolating a part of it for private use: creating a
“tunnel” through the internet or any public
network.
This is done by implementing sophisticated
security measures. See next slide.
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VPN (cont.)
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Used to establish secure intranets and
extranets
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The Internet is the main backbone network
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Relies on network firewalls, encryption, and
other security features to build a “pipe” through the
Internet
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Creates a private network without the high
cost of a separate proprietary connection
VPN (p188)
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Intranet:
Extranet:
Switching Techniques
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How can computers or nodes link to each other
on the network:
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Circuit switching: dedicated channel (path or circuit)
established for duration of transmission
Packet switching: message broken into packets
Packet: group of bits transmitted together
Switching Techniques (continued)
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Switching Tech. (cont.)
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Frame relay: high-speed packet-switching
protocol used in WANs
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Multi-protocol label switching: enhances
services like VoIP.
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Variable-sized packets routed quickly
Better ratio of data bits to non-data bits
Still broken into packages, but all will use the same
path on the network
Protocols
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Protocol: set of rules governing communication
between computers
Protocol is like human language and basic
understanding
Some protocols designed for WANs, LANs, and
wireless communications
Most important set of protocols called TCP/IP
TCP/IP
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TCP/IP: Transmission Control Protocol/Internet Protocol
– Ensures packets arrive accurately
– Ensures delivery of packets from node to node,
respectively
Internet backbone: highest speed channels
Host: computer connect directly to backbone
IP number: unique identification for device
DNS: Domain Name Service maintains character-based
names of IP numbers
What is your PC’s IP Address?
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Start > All Programs > Accessories
Command Prompt > ENTER
Type: ipconfig
So, what is your IP address
Let’s check for GOOGLE!!
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Still in command prompt:
Type: ping google.com
If you are having connectivity problems, you
can use the ping command to check the
destination IP address you want to reach and
record the results. The ping command
displays whether the destination responded
and how long it took to receive a reply.
Google.com
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OPEN the browser and type in the address
the ip address of google and ENTER
What is the DNS service doing?
TCP/IP (continued)
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Static IP number: permanent number assigned
to device
Dynamic IP number: temporary IP number
assigned for duration of connection
IP or URL Address:
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The Uniform Resource Locator is an address
that points to a specific resource on the Web
http://www.stanford.edu/jengk/useless.html
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http:// protocol for Web pages
www.standford.edu is the Domain name: it
identifies the computer that stores the Web pages
Jengk/ is the directory path; identifies where the
page is store on the computer
Useless.html is the document name or web page
Ethernet
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Ethernet: LAN protocol using coaxial cable, also
known as IEEE 802.3
Gigabit Ethernet: faster Ethernet connections
Devices on network contend with other devices
for transmission time
CSMA/CD protocol ensures no collisions in
transmission
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Know more about bands:
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See: http://www.disa.mil/jsc/speccht.html
Wireless Protocols
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IEEE 802.11: known as Wi-Fi (wireless fidelity)
– Supports wireless communication within 100 metres
of router with speed of 11 Mbps: 802.11b
– 802.11g Max speed 54 Mbps all in range 2.4-2.5 GHz
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Access point: Wi-Fi router connects to AP that
connects to the Internet.
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Access point (hotspot): allows Internet access within
range of equipment
Encryption: ability to scramble and code messages
– Use keys shared between sender and receiver
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Wireless Protocol (cont.):
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IEEE 802.15 Bluetooth: allows devices to
communicate within 10 metres
Examples: Wireless keyboards and mice,
microphones for mobile phones.
Wireless Protocols (continued)
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Worldwide Interoperability for Microwave
Access (WIMAX): increases range and speed of
wireless communication IEEE 802.16
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Mobile Broadband Wireless Access (MBWA):
similar to cell phone communications
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110 km, speed of 100 Mbps
Works with metropolitan area networks
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Compatible with IP services
Compatible with Wi-Fi and Bluetooth
Wireless Protocols (continued)
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Generations in Mobile
Communications
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Generations of mobile communication technologies
are determined by capabilities and transmission
speed:
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1G, First generation analog and circuit switching
2G, Second generation used digital voice encoding
2.5G, Speed 144 Kbps, packet switching and limited Internet
access
3G, speeds up to1 Mbps, support video, Internet access
4G, digital, packet switching, bandwidths up to 100 Mbps and
tighter security.
Future:
Internet Networking Services
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Variety of options to choose from when
subscribing to network services
Downstream: speed of receiving from
network
Upstream: speed of transmitting to network
Cable
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Internet links provided by television cable
firms
Cable connected to Internet server
At residence, cable split into TV set and
computer
Cable shared by all subscribers
Digital Subscriber Line (DSL)
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Digital subscriber line (DSL): data remains
digital through entire transmission; 8Mbps
Uses telephone lines connected to DSL
bridge/modem
Several types of DSL
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Asymmetric (ADSL) allows different upstream and
downstream rates
SDSL for short distances
Satellite
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Satellite services use microwaves
Service provider installs dish antenna, used
as communications satellite
Speeds up to 45 Mbps
GPS free satellite service
Fixed Wireless
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Fixed wireless: point-to-point transmission
between two stationary devices
Wireless Internet service provider (WISP)
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Provides fixed wireless service
Highly modular and scalable
Optical Carrier
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Optical carrier using optical fibre.
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Uses basic unit of 51.84 Mbps
Used by
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Expensive
High connection speeds
ISPs
Search engines
Content-rich Web sites
Broadband over Power Lines
(BPL)
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Broadband over Power Lines (BPL): uses
electric power lines to carry digital signals
Used by utility companies
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Monitor power consumption
Detect power failure
Track power outages
The Future of Networking
Technologies:
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Broadband Telephoning: VoIP
Radio Frequency Identification: RFID
Converging Technologies:
Broadband Telephoning:
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Voice over Internet Protocol: uses Internet
connection to conduct telephone
conversations using VoIP.
Regular telephone companies charge
according to number of minutes a call last
ISP charge customers a flat monthly
connection fee for connection to Internet
Three different topologies:
Technologies:
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PC-to-PC
PC-to-Phone
Phone-to-Phone
PC-to-PC:
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In this model, both caller and receiver must
have Internet phone equipment (VoIP) to talk
to each other.
The call is routed through an ISP such as
Netcom.
Both caller and receiver must have their
computers on to complete calls
PC-to-Phone
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These calls are routed like a normal
telephone call, except:
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The PC must have Internet phone equipment
A call is dialed to the ISP, routed back
through the internet backbone
And then sent back to the voive phone
network
Phone-to-Phone
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One caller would dial a code, similar to a
long-distance code
The ISP gateway will rout the call through the
Internet and
Then converts it the signal back to the voice
phone network upon reaching its connection.
Advantages/Disadvantages
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P202, 203
VoIP becomes portable
Radio Frequency Identification
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RFID tags tiny and need little power
Objects are embedded with tags that contain
a transponder:
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It’s a radio ‘transmitter-receiver’ that is activated
for transmission by a signal that is transmitted to it
The tag has a digital memory with a unique EPC
RFID:
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The interrogator
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An Arial
Transceiver
Decoder
Emits a signal activating the RFID tag so that
the interrogator can READ/WRITE data to it
Readers decode data stored in tag’s memory
and data passed to host computer
RFID:
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How do companies apply this technology to
the supply chain?
Future Uses of RFID
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Converging Technologies
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WebTV technologies allows one to add a settop box to a TV set, so that one can access
also the World Wide Web: connecting to the
Internet
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So TV technology and Web technology converges
in WebTV
Cell phones can act as Web phones
Wireless technologies combined in same
device enhance functionality
Summary
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Telecommunications is communication over
distance
Telecommunications technology has changed
the business environment
Different media have different bandwidths
Networks are classified according to reach
and complexity
Network can be turned into a virtual private
network (VPN)
Summary (continued)
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Two ways to switch a communication line: packet
switching and circuit switching
Network protocols are sets of rules to which all
devices on network must adhere
The Internet adheres to the TCP/IP protocol
Wireless technologies make it easy and affordable to
create wireless LANs
Organizations and individuals have variety of choices
when subscribing to networking services
Summary (continued)
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As Internet links become faster, Internet
telephoning is gaining in popularity
Wireless technologies support the
increasingly popular RFID technologies
Much like hardware, telecommunications
technologies are merging
Increasing numbers of employees now
telecommute