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INS 601
INS 601 INFORMATION
SYSTEMS MANAGEMENT
Telecommunications and
Networks
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INS 601
Telecommunications & Networks
Definition of Computer Network
Telecommunications Network Model
Types of Telecommunications Networks
Telecommunications media
Wireless technologies
Telecommunications Processors
Network Topologies
Network Architectures & Protocols
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INS 601
Computer Network
An interconnected collection of two or
more autonomous computers is called a
computer network
Objectives :-
Share information
Share storage space
Share other resources printers, scanners
etc.
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INS 601
Types of Computer Networks
Types of
Computer
Networks
Local AreaNetworks
(LAN)
Wide AreaNetworks
(WAN)
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Local Area Networks (LAN)
LANs are used to connect computers
within a limited physical area.
Components of LAN:-
File Server with Network OS
Client machine with NIC (Network Interface
Card)
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Wide Area Network (WAN)
WANs cover a large geographic area.
They are used by multinational
companies to transmit & receive
information among :-
Their employees,
Customers
Partners across cities / countries
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The business value of the Internet
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The business value of the Intranets
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Extranet between companies A & B
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The Role of Intranets
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INS 601
Telecommunication Network Model
Telecommunications is the exchange of
information in any form (voice, text,
image, audio, video) over the computer
based networks.
Hence computer networks are more
popularly called as telecommunication
networks.
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INS 601
The Practical Uses of Communications
Videoconferencing & Videophones
Videoconferencing - the use of television video and soundtechnology as well as computers to enable people in
different locations to see, hear, and talk with one another
http://www.cnn.com/2000/TECH/computing/09/05/picture.phones.ap/http://www.cnn.com/2000/TECH/computing/09/05/picture.phones.ap/7/28/2019 INS 601 - Telecommunications Networks - 23-11-09
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INS 601
Workgroup Computing & Groupware
Workgroup computing - teams of co-workers use
networks of microcomputers to share information and to
cooperate on projects
Made possible by networks, microcomputers, &
groupware
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INS 601
Telecommuting
Telecommuting - working
at home while in
telecommunication with the
office
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Virtual Offices
Virtual office - an often nonpermanent and mobile office
run with computer and communications technology
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Computer Network
Corporate or
external computer
access
Server
Shared
Printer
Workstations
tape drive
(backup)
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INS 601
Components of
Telecommunication Networks
LAN cardLAN card
LAN card
LAN card
Shared PrinterServer
TerminalTerminal Software
Telecommunications
Processor
(Router or Switch)
Internet
Firewall
Telecommunic
ations
Channels
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INS 601
Components of Telecommunications
Networks
TerminalNetwork PCs, network computers or informationappliances.
Telecommunication Processors
Support data transmission and reception betweenterminals & computers eg : Routers, switches,Modems
Telecommunications Channels
Over which data are transmitted and received. Eg.Copper wires, coaxial cables etc.
Telecommunication Software
Consists of programs that control telecommunicationsactivities and manage the functions oftelecommunications networks.
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INS 601
Figure: Components of
Telecommunications Network
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Factors Affecting How Data Is
Transmitted
Direction of transmission:simplex, half-duplex, &
full-duplex
Simplex transmission -
data can travel in only onedirection
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INS 601
Factors Affecting How Data Is
Transmitted
Direction of transmission:
simplex, half-duplex, &
full-duplex
Half-duplex transmission - data
travels in both directions but
only in one direction at a time
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INS 601
Factors Affecting How Data Is
Transmitted
Direction of transmission:
simplex, half-duplex, &
full-duplex
Full-duplex transmission -
data is transmitted back
and forth at the same time
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INS 601
TelecommunicationsMedia
Coaxial
Shield
Radio or Micro Waves
Fiber Optic Cable
antenna
Twisted Pair
reflective cladding
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Wired CommunicationsChannelsTwisted-pair wire - two strands of insulated copper wire,
twisted around each other
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Wired CommunicationsChannelsCoaxial cable - insulated copper wire wrapped in a solid
or braided metal shield, then in an external cover
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Telecommunications Media
Twisted pair wirethese are ordinary telephone wires
& they are most widely used medium for
Telecommunications
Transmission Speeds 2 million bps Unshielded (UTP)
Coaxial Cableconsists of a sturdy copper wire/
aluminum wire wrapped with spacers to insulate and
protect it. The cables cover minimize interference &
distortion of signals & allows high speed transfers
Transission speeds 200 Mbps to 500 Mbpsused
more for Cable TV systems and short distance
connection of computers.
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Telecommunications Media
Fiber Opticsusescables consisting of
one or more hair thin filaments of glass
wrapped in a protective jacket. They
conduct pulses of visible light elements(Photons)
Transmission speeds : Terabits (Trillions of
Bits)
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Wireless Technologies
Wireless Telecommunications technologies rely onMicrowave, Infrared & ISM band pulses to transportdigital Communications without wires betweencommunications devices.
Wireless Communications Technology AntennaAn electrical conductor or system of conductors
used either for radiating electromagnetic energy into space orfor collecting electromagnetic energy space.
TransmissionRadio Frequency electrical energy fromtransmitter is converted into electromagnetic energy by the
antenna & radiated into the surrounding environment(atmosphere, space, water etc)
ReceptionElectromagnetic energy impringing on theantenna is converted into radio frequency electrical energyand fed into the receiver.
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The Electromagnetic Spectrum,the Radio Spectrum, &Bandwidth
Radio frequency spectrum
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Wireless Network Technologies
Infra Red Technology
An Infrared (IR) LAN is limited to a single room, as
infrared light does not penetrate opaque walls.
Bluetooth Technology
Bluetooth is a wireless communication standard
developed by five major companies: Ericsson, IBM,
Intel, Nokia and Toshiba. Bluetooth is designed to be
used in low cost, low power consumption devices,such as mobile phones and personal digital assistants
(PDAs).
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Wireless Network Technologies
Wi-Fi Technology (IEEE 802.11b)In 1990, IEEE formed a new working group IEEE 802.11
specifically devoted to wireless LANs. IEEE 802.11b wirelessLAN operates on the 2.4 GHz band.
ISM Band :The industrial, scientific, and medical (ISM) radio bands were
originally reserved internationally for non-commercial use of RFelectromagnetic fields for industrial, scientific and medicalpurposes.
900 MHz band 2.4 GHz band (Bluetooth / WiFi)
5.8 GHz band
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Telecommunications Processors
Telecommunications Processors perform a variety of
support functions between the computers & other
devices in a telecommunications network.
Modem :Modulator Demodulator
Modem convert digital signals from a computer or
transmission terminal at one end of a communications
link into analog frequencies that can be transferred
through ordinary telephone lines (Modulation)
A modem at the other end converts transmitted data
back into digital form (Demodulation)
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INS 601
From the Analog to the Digital Age
Analog - continuous and varying in strength and/or
quality
Digital - communications signals or information
represented in a two-stat (binary) way
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Purpose of the Modem: ConvertingDigital Signals to Analog Signals & Back
Sending modem - modulatesdigital signals into analog signals
for transmission over phone lines
Receiving modem -demodulates the analog
signals back into digitalsignals
Modem - short for
modulate/demodulate
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Telecommunications Processors
Multiplexers
A Multiplexer Is a communications processor thatallows a single communications channel to carrysimultaneous data transmissions from many terminals.
This is done by two ways:-
Frequency Division Multiplexing
In FDM a multiplexer effectively divides a high speed channel
into multiple slow speed channels. Time Division Multiplexing
In TDM, the multiplexer divides the time each terminal canuse the high speed line into very short time slots.
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INS 601
Time Division Multiplexing
A B
DC
timeA C A C A
Computers A and B split their messages into packets and share
the transmission medium by taking turns sending the data.
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Frequency Division Multiplexing
A B
D
frequency
3500 Hz
A
C
Computers A and C split the frequency: A uses a higher spectrum.
By listening only to the assigned frequency, multiple transmissions
can occur at the same time.
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INS 601
Telecommunications Processors
Inter network ProcessorsTelecommunications networks are interconnected by special purpose
communications processors called Internet-work Processors, such
as :-
SwitchMakes connections betweenTelecommunications circuits in a network.
RouterIs an Intelligent Communications Processor
that interconnects networks based on different
rules/protocols, so that a telecommunicationsmessage can be routed to its destination.
HubIs a Port switching communications processor.
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Telecomm Processors
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Telecommunications Software
Telecommunications and Network ManagementSoftware may reside in PCs, Servers, Mainframes &Communications Processors (such as Multiplexers &Routers)
Network Management Functions:- Traffic ManagementAvoid congestion/Optimise use
SecurityAuthentication/Encryption/Auditing/Firewall
Network MonitoringTroubleshoot/watch & inform the
Network Administrators of problems Capacity PlanningSurvey network resources and
traffic patterns & determine how best to accommodatethe needs of the network as it grows & changes.
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INS 601
Network Topologies
Network
Topologies
RING
Network
STAR
Network
BUS
Network
Network may be represented as a collection ofnodes,some of which are connected by links. Network topology
is determined only by the configuration of connections
between nodes, distances between nodes, physical
interconnections, transmission rates, and/orsignal types
are not a matter of network topology, although they maybe affected by it in an actual physical network.
http://en.wikipedia.org/wiki/Node_%28networking%29http://en.wikipedia.org/wiki/Configurationhttp://en.wikipedia.org/wiki/Transmission_%28telecommunications%29http://en.wikipedia.org/wiki/Signalhttp://en.wikipedia.org/wiki/Signalhttp://en.wikipedia.org/wiki/Transmission_%28telecommunications%29http://en.wikipedia.org/wiki/Configurationhttp://en.wikipedia.org/wiki/Node_%28networking%297/28/2019 INS 601 - Telecommunications Networks - 23-11-09
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RING Topology
RING TopologyAll devices are connected to one another in the shape of
a closed loop, so that each device is connected
directly to two other devices, one on either side of it.All of the nodes are connected in a closed loop.
Messages travel around the ring, with each node
reading those messages addressed to it. One of the
advantages of ring networks is that they can span
larger distances than other types of networks, such as
bus networks, because each node regenerates
messages as they pass through it.
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RING Topology
In a ring topology, all the computers in the network are connected
in a closed loop. The data signal travels around the loop in one
direction, passing through each computer. Whereas bus topology
is passive, in a ring topology each computer boosts the signal
before sending it on to the next computer. Because the signal
must pass through each computer, the failure of one computer
can cause the network to fail.
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Topology of LANs
Ring network - one inwhich all microcomputersand other communicationsdevices are connected in
a continuous loop
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Star Topology
A star topology is designed with each node (file server,
workstations, and peripherals) connected directly to a
central network hub Data on a star network passes
through the hub or concentrator before continuing to
its destination. The hub or concentrator manages andcontrols all functions of the network.
http://fcit.coedu.usf.edu/network/glossary.htmhttp://fcit.coedu.usf.edu/network/glossary.htmhttp://fcit.coedu.usf.edu/network/glossary.htmhttp://fcit.coedu.usf.edu/network/glossary.htm7/28/2019 INS 601 - Telecommunications Networks - 23-11-09
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INS 601
BUS TOPOLOGY
A linear bus topology consists of a main run of cable
with a terminator at each end. All nodes (file server,
workstations, and peripherals) are connected to the
linear cable. Ethernet networks use a linear bus
topology.
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Topology of LANs
Bus network - one inwhich all communicationsdevices are connected to
a common channel
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Star Topology
Advantages of a Star Topology
Easy to install and wire.
No disruptions to the network when connectingor removing devices.
Easy to detect faults and to remove parts.Disadvantages of a Star Topology
Requires more cable length than a linear topology.
If the hub or concentrator fails, nodesattached are disabled.
More expensive than linear bus topologiesbecause of the cost of the concentrators.
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Advantages of a Linear Bus Topology Easy to connect a computer or peripheral to a linear bus.
Requires less cable length than a star topology.
Disadvantages of a Linear Bus Topology
Entire network shuts down if there is a break in the maincable.
Terminators are required at both ends of the backbonecable.
Difficult to identify the problem if the entire network shuts
down. Not meant to be used as a stand-alone solution in a large
building.
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Network Architectures & Protocols
Until recently, the use of telecommunication was
hampered by the lack of sufficient standards for
interfaces between hardware, software &
communications channels.
In response, telecommunications manufacturers &National & International Organisations have developed
standards calledPROTOCOLS, & master plans
calledNETWORK ARCHITECTURES to support the
development of advanced Data Communications.
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Protocols and Network Architectures
Protocols:
Protocols are a standard set of rules & procedures for
the control of communications in a network.
Network Architectures:The goal of Network Architectures is to promote an:-
- Open
- flexible- efficient telecommunications environment.
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TCP/IP Model
TCP/IP commonly refers to a network
architecture, but this acronym also refers to 2
protocols that are closely bound: a transport
protocol, TCP (Transmission Control Protocol)and a network protocol, IP (Internet Protocol)
The Internet architecture is on the basis of
TCP/IP
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Comparison Between TCP/IP & OSI
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TCP/IP Model
The data link layer
In more concrete terms, this implementation is typicalof the technology used to build the local network(LAN). For example, LANs use Ethernet; Ethernet is
an implementation of the data link layer. The internet layer
This layer is the key of the architecture. Because ofthe major role of this layer in the packet deliveryprocess, the critical point of this layer is routing. For
this reason, we may compare this layer to the networklayer of the OSI model.
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TCP/IP Model
The transport layerIt has the same role as the transport layer of the OSI model: it is usedto make peer entities dialog with one another.Officialy, this layer onlyhas two possible implementations: the TCP protocol (TransmissionControl Protocol) and the UDP protocol (User Datagram Protocol). TCPis a reliable and connection-oriented protocol that delivers packets
without errorfrom a machine of an internet to another machine of thesame internet. On the other hand, UDP is a very simple protocol: it is anon-reliable and connectionless protocol. Using it presupposes that wedo not need flow control, either preserving the order of packets.
The application layer
Contrary to the OSI model, this layer is immediately bound to the
transport layer, simply because the session and presentation layers areuseless. This layer holds all high level protocols, such as Telnet,TFTP (trivial File Transfer Protocol), SMTP (Simple Mail TransferProtocol), HTTP (HyperText Transfer Protocol). The main issue for thislayer is that it can use both TCP or UDP protocols.