INS 601 - Telecommunications Networks - 23-11-09

7/28/2019 INS 601 - Telecommunications Networks - 23-11-09

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INS 601

INS 601 INFORMATION

SYSTEMS MANAGEMENT

Telecommunications and

Networks


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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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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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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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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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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/


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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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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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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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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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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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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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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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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 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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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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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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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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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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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%29


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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.htm


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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.

INS 601 - Telecommunications Networks - 23-11-09

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