HSSN2-01-DataCommunication

8/6/2019 HSSN2-01-DataCommunication

1/75

Overview of Data Communication

and Networking

Prepared by: KL First Prepared on: 13-12-04 Last Modified on: 24/07/2005

Quality checked by: xxx

Copyright 2004 Asia Pacific Institute of Information Technology

Hardware and Software Systems and Networks 2CT024-3-2

Level-2


2/75

CT014-1 Hardware, Systems Software and Networks Chapter 2 2

Topic & Structure of the lesson

Data Communications

Networks

The Internet

Protocols and Standards


3/75


Learning Outcomes

At the end of this session you should beable to:-

Define Components, Data Representationand Direction of Data Flow

Identify Distributes Processing, NetworkCriteria, Physical Structures and Categoriesof Networks

Understand A Brief History and the InternetToday

Understand Protocols, Standards, StandardsOraganisations and Internet standards


4/75


Key Terms you must be able to

use

If you have mastered this topic, you should

be able to use the following terms correctly

in your assignments and exams:- Data Communication

Networks

The Internet

Protocols and Standards


5/75


Overview of Data Communications and Networking


6/75


Overview

Data Communication is sent data from one place toanother.

Data communication between remote parties called

Networking. Networks are divided into two main categories: LAN and

WAN.

Internet is a collection of LAN and WAN held together byinternetworking devices.

Protocol refer to the rules; a standard is a protocol thathas been adopted by vendors and manufactures.

Network Models serve to organize, unify, and control thehardware and software components of datacommunication and Network.


7/75


Data Communication

The effectiveness of a datacommunications system depends on threefundamental characteristics:

Delivery the system must deliver data tothe correct destination.

Accuracy the system must deliver the

data accurately. Timeliness The system must deliver data

in a timely manner.


8/75


Data Communication

Components

Data Representation

Direction of Data Flow


9/75


Components

A data communications system has fivecomponents

Message The information (data) to be

communicate. It can consist of text, number,

pictures, sound or video or any combination of

these.

Sender The device that sends the data

message. It can be a computer, workstation,telephone handset, video camera, and so on.

Receiver The device that receives the

message. It can be computer, workstation,

telephone handset, video camera, and so on.


10/75


Components

Medium The transmission medium is the

physical path by which a message travels

from sender to receiver. It could be atwisted-pair, coaxial cable, fiber-optic

cable, or radio waves (terrestrial or

satellite microwave).

Protocol A set of rules that governs data

communications. It represents an

agreement between the communication

devices.


11/75


Five components of data communication


12/75


Data Representation

Information today in different forms such

Text

Number

Images

Audio

Video


13/75


Direction of Data Flow

Communication between two devices canbe Simplex, half-duplex, or full-duplex.

Simplex Unidirectional, Only one of thetwo devices on a link can transmit; theother can only receive

Half-duplex Both station can transmit

and received, but not at the same time. Full-Duplex Both station can transmit

and receive simultaneoulsy.


14/75


Simplex

Example : Keyboard can only introduce input

Monitor can only accept output


15/75


Half-duplex

Example : Walkie-talkies


16/75


Full-duplex

Example : Telephone


17/75


Networks

Distributed Processing

Network Criteria

Physical Structures

Categories of Networks


18/75


Distributed Processing

Most networks use distributed processing,

in which Task is divide among multiple

computers. Instead of a single largemachine being responsible for all aspects

of a process.

The advantages of distributed processing

is security, distributed databases,

collaborative processing, faster problem

solving.


19/75


Network Criteria

A network must meet a certain criteria.

Performance include transit time and

response time, number of users,transmission medium and efficiency of thesoftware.

Reliability Frequency of failure, time

takes to recovery from a failure andnetworks robustness in a catastrophe.

Security Protection data fromunauthorized access.


20/75


Physical Structures

Point-to-point The entire capacity of the

link is reserved for transmission between

those two devices. Multipoint (also called multidrop) Two

specific devices share a single link, it is a

timeshare connection.

Physical topology There are four basic

topologies possible: mesh, star, bus and

ring.


21/75


Point-to-point connection

Example : Television channels by infrared remote control


22/75


Multipoint connection


23/75


Categories of topology


24/75


Fully connected mesh topology (for five devices)

Mesh topology


25/75


Mesh Topology

Every device has a dedicated point-to-point link

to every other device.

The term dedicated means that the link carries

traffic only between the two devices in connects.

A fully connected has n(n-1)/2 physical channels

to link n devices.

Usually implemented in a limited fashion forexample, as a backbone connecting the main

computers of a hybrid network that can include

several other topologies.


26/75


Advantages of a Mesh Topology

The use of dedicated links guarantees thateach connection can carry its own data load.

Eliminating the traffic problems that can occur

when links must be shared by multipledevices.

It is more robust. If one link becomesunusable, it does not incapacitate the entiresystem.

It is more secure and privacy, every messagetravels along a dedicated line, only the

intended recipient sees it.


27/75


Disadvantages of a Mesh

Topology

Every device must be connected to every

other device, installation and reconnection

are difficult. The complete bulk of the wiring can be

greater than the available space (in walls,

ceilings, or floors) can be expensive.


28/75


Star topology


29/75


Star topology

Each device has a dedicated point-to-point link

only to a central controller, usually called a hub.

Does not allow direct traffic between devices.The controller acts as an exchange.

Less expensive than a mesh topology.

Each device need only one link and one I/Oport to connect it to any numberof others.

It is easy to install and reconfigure


30/75


Star topology

Less cabling needs to be addition, moves, and

deletions involve only one connection: between that

device and the hub.

It is more robustness. If one link fails, only that link isaffected.

It is easy fault identification and fault isolation.

However, star required far less cable than a mesh,

each node must be linked to a central hub. For this

reason more cabling is required in a star than in some

other topologies (such as ring or bus)


31/75


Bus topology


32/75


Bus topology

One long cable acts as a backbone to link all thedevices in a network. On the other hand, is multipoint.

A drop line is a connection running between the

device and the main cable. Nodes are connected to the bus cable by drop lines

and taps.

As a signal travels along the backbone, some of its

energy is transformed into heat. The heat becomes weaker and weakeras it has to

travel farther and farther.


33/75


Advantages of Bus topology

Easy of installation

Backbone cable can be laid along the

most efficient path, then connected to thenodes by drop lines of various lengths.

A bus uses less cabling than mesh or star

topologies, redundancy is eliminated.


34/75


Disadvantages of Bus Topology

Difficult reconnection and fault isolation.

It can be difficult to add new devices.

Signal reflection at the taps can causedegradation in quality.

The degradation can be controlled by

limiting the numberand spacing of devicesconnected to a given length of cable.


35/75


Disadvantages of Bus Topology

Adding new devices may therefore require

modification orreplacement of the

backbone. A fault orbreak in the bus cable stops all

transmission,

The damaged area reflects signals back inthe direction of origin, creating noise in

both directions.


36/75


Tree topology


37/75


Tree topology

It is a variation of a star.

Node in a tree are linked to a central hubthat controls the traffic to the network.

The central hub in the tree is an active huband contains a repeater.

The secondary hubs may be active or

passive hubs. A passive hub provides a simple physical

connection between the attached devices.


38/75


Ring topology


39/75


Ring topology

A signal is passed along the ring in one

direction, from device to device, until is reaches

it destination.

Each device in the ring incorporates a repeater.

A ring is relatively easy to install and

reconfigure.

The add or delete a device requires changingonly two connections.

If one device does not receive a signal within a

specific period, it can issue an alarm.


40/75


Categories of networks

Category a network falls is determined by its

size, its ownership, the distance it covers, and

its physical architecture.


41/75


Local-Area Network (LAN)


42/75


LAN (Continued)


43/75



Usually privately owned and links the devices in

a single office, building, or campus.

Currently, LAN size is limited to a few

kilometers.

LAN are designed to allow resources to be

shared between personal computers or

workstations. The resources to be shared can include

hardware (e.g., Printer), software (e.g., an

application program), or data.


44/75



Software can be stored on this centralserverand used as needed by the wholegroup.

Can control licensing restrictions on thenumber of users per copy of software.

Traditionally, data rates in the 4 to 6

megabits per second (Mbps) range. Today, however, speeds are increasing

and can be reach 100 Mbps with gigabitsystem in development.


45/75


Metropolitan-Area Network (MAN)


46/75


Designed to extend over an entire city.

It may be a single network such as a cabletelevision network.

Connecting a number of LANs into a largernetwork so that resources may be sharedLAN-to-LAN as well as device-to-device.

Many telephone companies provide apopular MAN service called SwitchedMulti-megabit Data Services (SMDS)

Metropolitan-Area Network (MAN)


47/75


Wide Area Network (WAN)


48/75


Wide Area Network (WAN)

Provides long-distance transmission of

data, voice, image and video information

overlarge geographic areas that maycomprise a country, a continent, or even

the whole world.

A WAN that is wholly owned and used by

a single company is often referred to as

an enterprise network.


49/75


The Internet

A Brief History

The Internet Today


50/75


The Internet

The Internet has revolutionized many aspects of

our daily lives.

It brought a wealth of information to our

fingertips and organized it for our use.

An internet (lowercase letter i) is two or more

networks that can communicate with each other.

The Internet (uppercase letter I), a collaborationof more than hundreds of thousands

interconnected networks.


51/75


The Internet

In the mid-1960, Computers from differentmanufactures were unable tocommunicate with one another.

TheAdvanced Research Projects Agency(ARPA) in the Department of Defense(DOD) was interested in finding a way to

connect computers. In 1967,ARPA presented its ideas forARPANET, a small network connectedcomputers.


52/75


The Internet

In 1969 four university were connected via

the Interface Message Process (IMP) to

from a network. Software called the Network Control

Protocol (NCP) provided communication

between the hosts.


53/75


Internet today


54/75


Internet today

The Internet today made up of many wide-

and local area networks joined by

connecting devices and switching stations.

Today most end users who want Internet

connection use the services ofInternet

service providers (ISPs).

There are international service providers,

national service providers, regional service

providers, and local service providers.


55/75


Service Providers

International Service Providers connectnations together.

National Service Providers (NSP)backbone networks are connected bycomplex switching stations, call networkaccess point (NAP)

Regional Internet Service Providersconnected to one or more NSPs.

Local Internet Service Providers providedirect service to the end users.


56/75


Protocols and StandardsProtocols and Standards

ProtocolsProtocols

StandardsStandards

Standards OrganizationsStandards Organizations

Internet StandardsInternet Standards


57/75



Protocol is a set of rules that govern datacommunications. It define what, how and whenis communicated.

The key elements of a protocol are syntax,semantics, and timing.

Syntax The structure or format of the data.

Semantics The meaning of each section of

bits. Timing Two characteristics: When data should

be sent and how fast they can be sent.


58/75



Standards agreed-upon rules.

Provide guidelines to manufactures,

vendors, government agencies, and otherservice providers to ensure the kind of

interconnectivity necessary in todays

marketplace and in international

communications.


59/75



Data communication standards fall into

two categories:

De facto Standards that have not beenapproved by an organized body but have

been adopted as standards through

widespread use are de factor standards.

De jurethat have been legislated by an

officially recognized body are de jure

standards.


60/75


Standards Organizations

Standards are developed through thecooperation ofstandards creation committees,forums, and government regulatory agencies.

International Organization for Standardization(ISO).

International Telecommunication Union Telecommunication Standards Sector (ITU-T).

American National Standards Institute (ANSI). Institute of Electrical and Electronics Engineers

(IEEE).

Electronic Industries Association (EIA).


61/75


International Organization

for Standardization (ISO)

The ISO is a multinational body whose

membership is drawn mainly from the

standards creation committees of various

governments throughout the world.

The ISO is active in developing

cooperation in the area ofscientific,

technological, and economic activity.


62/75


International Telecommunication Union

Telecommunication Standards Sector (ITU-T).

This committee was devoted to the

research and establishment of standards

for telecommunications in general.

Created standards for telephone

communications (V Series) and

standards for network interfaces and

public networks (X Series)?


63/75


American National Standards Institute

(ANSI).

It is a completely private, nonprofit

corporation not affiliated with U.S. federal

government.

All ANSI activities are undertaken with the

welfare of the united States and its citizens

occupying primary importance.


64/75


Institute of Electrical and Electronics

Engineers (IEEE).

The largest professional engineering

society in the world.

Organization consists of computerscientists and engineers is known for its

development, creativity, and product

quality in the fields of electrical

engineering, electronics, radio as well asin LAN standards,


65/75


Electronic Industries Association

(EIA).

A nonprofits organization devoted to the

promotion of electronics manufacturing

concerns.

Its actives include public awareness

education in the field of information

Technology.

Agency developed standards for electrical

connections and the physical transfer of

data between devices


66/75


Forums

Forums work with universities and users totest, evaluate, and standardize newtchnologies.

Forums concentrating their efforts on aparticular technology.

It able to speed acceptance and use of

those technologies in thetelecommunications community.

Forums present their conclusions to thestandards bodies.


67/75


Regulatory Agencies

Federal Communications Commission(FCC) is regulation by government

agencies.

The purpose of these agencies is toprotect the public interest by regulating

radio, television, and wire/cable

communication.

The FCC has authority over interstate and

international commerce as it relates to

communications.


68/75


Quick Review Questions

Refer to tutorial.

S f O i f D t


69/75


Summary of Overview of Data

Communication and Networking

Data communication is the transfer of data fromone device to another via some form oftransmission medium.

A data communications system must transmitdata to the correct destination in an accurateand timely manner.

The five components that make up a data

communications system are the message,sender, receiver, medium, and protocol.

Text, numbers, images, audio, and video aredifferent forms of information.


70/75




Data flow between two devices can occur

in one of three ways: simplex, half-duplex,

or full-duplex.

A network is a set of communication

devices connected by media links.

In a point-to-point connection, two and

only two devices are connected by a

dedicated link. In a multipoint connection,

three or more devices share a link.

S f O i f D t


71/75




Topology refers to the physical or logicalarrangement of a network. Devices may bearranged in a mesh, star, bus, or ring topology.

A network can be categorized as a local areanetwork (LAN), a metropolitan-area network(MAN), or a wide area network (WAN).

A LAN is data communication system within a

building, plant or campus, or between nearbybuildings.

A MAN is a data communication systemcovering an area the size of a town or city.

S f O i f D t


72/75




A WAN is a data communication systemspanning states, countries, or the whole world.

An internet is a network of networks.

The Internet is a collection of many separatenetworks.

TCP/IP is the protocol suite for the Internet.

There are local, regional, national andinternational Internet service providers (ISPs).

A protocol is a set of rules that governs datacommunication; the key elements of a protocolare syntax, semantics and timing.

S f O i f D t


73/75




Standards are necessary to ensure that

products from different manufacturers can

work together as expected.

The ISO, ITU-T, ANSI, IEEE, and EIA are

some of the organizations involved in

standards creation.

Forums are special-interest groups that

quickly evaluate and standardize new

technologies.


74/75


Q & A

Question and Answer Session


75/75

Next Session

Network Models

Documents

HSSN2-01-DataCommunication