Sunday, November 24, 2019

Network Topology Advantages and Disadvantages


 Network Topology Advantages and

 Disadvantages


 Network Topology Advantages and  Disadvantages

Topology is a method in which networks are physically connected together networks. Topology determines complexity of connecti ve computers and therefore the cost of network cable installation it also determine the strategy for physically expanding the networks in future.

Different topologies are as follows-

BusTopology 

In Bus Topology computers are connected by a single length cable with a terminator at each end. It is very simple and most widely used for Lan Computing. It is passive topology that means only one computer can send message at a time. So, the numbers of ocmputers connected in a bus affects the speed of the network. A computer must wait until the bus is free before it can transmit each node is connected to two others except the machine at either end of the cable which are connected only two one other node (Linear Topology)

Advantages of Bus Topology


  • The Bus Topology is simple reliable easty to use and understand small sized Lan's.


  • Bus requires or needs least amount of cable to connect the computers. Therefore, it is less  expensive than other cabling arrangements.


  • It is easy to extend a bus. Two cables can be joined into one longer cable with a connector. It allows computers to join the computer network.

 Disadvantages of Bus Topology


  • Heavy network traffic can slow down a bus considerably. This is because any computer can transmit any time.


  • A bus network with many computer can spend a lot of Bandwidth with the computers interuppting each other instead of communicating.


  • Trouble shooting  a bus is difficult cable can break from any where that cause communication fault.


  • Cable break or loose connectors causes the whole network down.

 Ring Topology


This layout is similar to the linear bus bus except that the nodes are connected in a circle using cable segment. In this layout each node is physically connected only to two other nodes.

Each node passes information passage along to the next until it arrives intendent destination. Since each compute retransmit wht it receive.  There is no termination because there is no end after ring. Performance of on this topology is faster  because each portion of the cabling system is handling only data floor between two machine.

It can  be found of P2P networkwhere each machine manages both information processing and distribution of the file. It is known as Circular topology.

 Advantages of Ring Topology


  • Because every computer is given equal access to the token no noone computer can monopolies the network.


  • The fair sharing of the network allows the network to Degrade gracefully. It continues the function in a slower manner to fail completely.

 Disadvantages of Ring Topology


  • Failure of one computer on the ring affects the whole network.


  • It is difficult to trouble shoot.


  • Adding or removing computers disrupts the network.

 Star Topology


Each computer on a star network communicates with a central hub that recents the message either to all the computers or all only to destination computer. The hub in a broadcast star network can be active or passive. Star is a example of centralize topology  where a central computer (server) is responsible for the whole network . Nodes request to server for communication. It is known as Centralize Topology.

 Advantages of Star Topology


  • It is much easier to modify or add new computers to a star network.


  • Single computers failures do not necessarily bring down the whole star network.


  • The hub can detect the network fault on isolate offending computer or network cable and allow rest of network to continue its operations.


  • You can use several cable type in the same network with the hub that can accomodate multiple cable types.

 Disadvantages of Star Topology


  • If the central hub fails the whole network fails to operate.


  • many star network requires a device at the central point to re-broadcast  or switch the network traffic.


  • It is costly to manage star network.


Mesh Topology (Pully connected)


It is a fully connected topology in this all devices are connected with many redudant interconnection between network nodes.

In a well connected topology, every node has a connection to every other node in the network. The cable requires are high. Failure in one of the computer does not cause the network breakdown , as they have alternative parts to othe computer. No of connected input and output devices.

Advantages of Mesh Topology


  • Use of dedicated links eleminates traffic problems.


  • Failure in one of the computer doesn't affect the entire network.


  • Point to point link makes fault isolation easy.


  • It's robust.


  • Privacy between computers is maintained as message travel along dedicated path.


Disadvantages of Mesh Topology


  • The amount of cabling required is high.


  • A large number of Input/Output ports are required.


Tree Topology (Hairarchy Topology)


Tree topology is a LAN topology in which only one root exit between two any node on the computer. The pattern of connections resembles a tree in which all branches spring from root. Tree topology is a Hybrid Topology . It is similar to the star topology but nodes are connected to the secondary hub which in term each to the central hub. In this topology all groups are star configured network are connected  to linear bus backbone.


Advantages of Tree Topology


  • More than one server.


  • Installation and configuration are easy.


  • Fault can be detected or teased easily.


  • The addition of secondary hub allows more devices to be attached to central hub.


  • Support multitypes cable such as – STP, UTP, ordinary telephone cable etc.

 Disadvantages of Tree Topology


  • More cable require.


  • Failure in the root hub brings to entire network to the hard.


 Difference between Tree and Star Topology


Tree Topology
Star Topology
All devices are not connected to the central hub directly.
All devices are connected to the central hub.
More than one central hub are possible.
There is only one central hub.
The addition of secondary hub allows more devices to be attach the central hub.
In orders for the nodes to communicate hub allows more devices to be across the network data always passes through the central hub.
Less cabling is required in compared to star topology.
More cabling is required

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Monday, November 18, 2019

Types of Network- P2P and DNS Addressing System


Types of Network-

P2P and DNS Addressing System


Types of Network- P2P and DNS Addressing System

Client Server


A network architecture in which each computer or processor on the network is either a client or a server . Each client a server connected to a network can also referred to as a note. Describe of architecture in some time referred two tier. It allows devices to share file and resources. Client server application consist of a server portion when the most processing and storage is perform and a client when the most processing and storage is perform and a client portion that provides a user interface. Each client sense data as request to server. In turn sever access, process and return them to client.


Characteristics of Client

  • Activate master computer.
  • Initiates request.
  • Wait for and receive replys.
  • Connects to one or more number of server at one time.
  • Typically interacts directly with end user using a GUI.

 Characteristics of Server

  • Waits for request from clients.
  • Upon receipt of request, it process them and then offers replies.
  • It usually accepts connections from a larger no of clients.
  • It does not interact directly with end-users.

 Peer to Peer Computer Network


Peer to Peer network is a type of network in which each computer or work station managed independently and one network have equal rights for communication with each other, sharing resources and validating users.

This network is used for connecting nodes in ordered to share content files containing audio, video or anything in digital form.

Types of P2P Network


Basically P2P networks are classified into three categories-

  1. Collaborative computing
  2. Instant messaging
  3. Affinity Communities

 Collaborative Computing


It refers to distributed computing. It combines the idle or unused CPU processing power or free disk space of many computers in the network. It is popular in science and biotech organisation where computer processing is required.

Instant messaging


One very common form of P2P networking is instant messaging where applications, such as MSN (Microsoft Network) etc. allows user to chat via text message in real time.

 Affinity Communities


It is a group of P2P network that is based around file sharing and widely known due to legal issues surrounding the direct file sharing group like napster.

Comparison of Client Server Architecture with

 P2P architecture


Aclient server architecture enables roles and responsibility of the computing system to be distributed among several independent computers that are known to each other . Only through a network this creates additional advantage to this architecture.

Ease of maintenance , possible to replace, repair, upgrade, or even relocate a server while its client remain both unaware an unaffected by a change.

All the data stored on the servers which generally have for greater security controls than most client.

Servers can better control access and resources , to guarantee that only those client with the appropriate permissions may access and change data.

Since data storage centralized updates to those data are for easierto administrate that would be possible under P2P system.

IP Addressing


IP, stands for Internet Protocol,is a number or value that is used to uniquely identify a computer on the Internet. It is a 32-bit value and it is divided into four different  section. All these sections are separated by a period.

Each sections is of 8-bits and values can be presented from 0 to 255 each section is known as octet. Every time when computer connects to Internet, ISP assigns IP address dynamically.

DNS Addressing


The purpose of DNS is to translate domain names into IP address and this service is known as DNS. If DNS, server does not know how to translate a particular domain name, it asks another DNS server and this process continues until the correct IP address returned.

DNS scheme uses alphabets and it is easier to remember, but  actually each domain name also have a address and DNS scheme is used to convert these domain into it's corresponding address.

DNS is divided into following three categories-

  1. Generic Domain
  2. Country Domain
  3. Inverse Domain

 Generic Domain


The generic domain defined register host according their generic behaviour each know node in the tree defines a domain which is an index to the domain name database . The first level is the generic domain allows 7 possible 3 character level.


Level                                      Description
.com                                       Commecial Oranization
.edu                                        Educational Institution
.gov                                        Government Institution
.int                                          Intenational Organization
.mil                                         Military Groups
.net                                         Network Support Centers
.org                                        Non Profit Organization

 Country Domains


The country domain section follows the same format as he generic domain but uses two character country abbreviations e.g. .us for United States, .in  for India in place of three charcter organizaional abbreviations at the first level. Second level labels can be organizational , or they can be more specific, national destinations. The united States for example, uses state abbreviations as a subdivision of "us" (e.g. , .ca,.us)

 Inverse Domain


The Inverse Domain is used to map an address to a name. This may happen, for example, when a server receive a request from a client to do a task. Whereas the server has a file that contains a list of authorized clients, the server list only the IP address of the client (extracted from the received IP packet) to.


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Monday, November 11, 2019

Computer Networking-Types of Network


Computer Networking-Types of Network

Computer Networking-Types of Network

What is Network?

An interconnection of computer and pheriperal devices with carriers and data communication devices for the purpose of exchanging data or information is known as Network.

"A computer network is simply a group of computers that are so connected that resources than can be shared and information can be exchaned."

Need of Networking


The major reasons for need of networking are as follows-

Resource Sharing


The aim is to make all programs, data and pheripherals available to authorised user on the network irrespective of physical location of resources.

Realiability


This is provided by having an alternative source of data available for use, e.g. file can be replicated onto 3 pcs, so that if one of them is unavailable due to hardware failure, the other PC can be used.

 Financial Benefits


Small computer have better price to performance ratio as compared to large ones.

 Better Communication Medium


In an organisation with a number of branches os for off places, networking of computer facilities cheap and easy mode of communication. It is possible to transfer any kind of information to any other destination immediately.


Access to remote data base


By getting access to remote data base it is possible to get rid of unnecessary trouble and wastage of precious time. From a remote place in any part of world a user can book a flight ticket, accomodation in hotels and so on.

Types of Network 

On the basis of geographical area, network can be categoriseed into-
  • LAN (Local Area Network)
  • MAN (Metropolitan Area Network)
  • WAN (Wide Area Network)


S.No.
Particulars
LAN
MAN
WAN
1
Full Form
Local Area Network
Metropolitan Area Network
Wide Area Network
2
Location
Located in Buildings,Offices etc.
Within a  city
Worldwide or Global
3
Connection
No Modem Require
Modem telephone require
Satellite connection and other devices
4
Data rate
High Data rate upto 100 Mbps
Less than LAN
Lowest Data rate
5
Installation
Easy to install
Less Easy
Difficult
6
Errors
Less errors
Error Occurs
High rate of Errors

LAN


Local Area Network is usually, privately owned by and links the devices in a single office, building or campus depending on needs.

LAN is a computer network that spans a relatively small area LANs are capable of transmitting data at very fast rate, much faster than what can be transmitted over a telephone line. Different  kinds of protocols are there  (Ethernet taken ring etc.) each with their own advantages and disadvantages.
Maximum Data transfer rate is upto 100 Mbps.

 

Advantages of LAN (Local Area Network)


LANallows sharing of expensive resources e.g. coloured,lajer printers and high capacity mass storage devices among a number of users.

LANs allows high speed of exchange of communication between key people in an organisation.
LAN contributes in increasing productivity.

LAN provides the catalyst to increase the range of  potential applications for the PCs where an application package can be used by users.

 Disadvantages of LAN (Local Area Network)


The financial cost of LANs is still high.

LAN software requires memory space in each of computer used on network.

LAN adds another level of complexity of computer operations.

You may face a situation where, the entire network suddenly locks up because one user has made a mistake.

Some kind of security system must be implemented in order to protect confidential data.


MAN


A Metropolitan Area Network is designed to extent over an entire city. It may be single net such as cable TV net or it may be a means of connecting a no. of LANs to form a large network. MANs are usually characterised by very high connection by fibre optic cable or other digital media.

A MAN can support both data and voice.

WAN


Wide Area Network It provides long distance transmission of data, voice , image over large graphical areas that may compromise a country , continent or even whole world computers of WAN are usually connected through public network such as telephone systems, leased lines or satellite e.g. indonet, banking, networks, stock, brokerage, network.


Types of Wide Area Network


There are two types of WAN-


Short Notes on Computer Networking


Nodes


The PCs and the servers are known as network devices or network nodes. In general, a device or node is connected directly to a network cable or data path.

Host


The term host refers to a microcomputer attached to a network device. It may also refer to the native operating system on a workstation.

 Workstation


A work station is a powerful PC used for a node on a network primarily used to run application program. PCs can be used as a work station.

 Bandwidth


It refers to a difference between the highest and the lowest frequencies of a transmissions channel.
"A channel is the medium used to carry information or data from a point to another."


Broadband


In telecommunication , broadband is wide brandwidth data transmissions which transports multiple signals and channels.

Interoparability 

It is the capability to communicate , execute programs or transfer data among various  functional units in a way that requires the user to have little or no knowledge of the major characteristics of those units.

NetworkAdministrator


Network Administrator is a person who manages the maintenance and use of a network. Network management refers to maintenance and administration of large scale computer network and tele-communication networks at top level.
 It includes performance of following functions-

  • Initial Network planning
  • Frequency allocation, predetermined traffic routing to support load balancing.
  • Gyptographic key distribution authorization.
  • Configuration Management.
  • Fault Management
  • Security Management
  • Performance Management
  • Bandwidth Management
  • Accounting management


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Friday, November 1, 2019

Uses of Information Technology - How we can use it?


Uses of Information Technology

Uses of Information Technology - How we can use it?

 

Teachers commonly use Information Technology for administrative tasks. Teachers most often use Information Technology for routine tasks (record keeping, lesson plan development, information presentation, basic information searches on the Internet.)


Types of usage of Information Technology correlate with teacher pedagogical philosophies. Teachers who use ICTs the most- and most effectively – are less likely to  use traditional  transmission method pedagogies. Teachers who use more types of software tend to practice more constructivist pedagogies.

 Use of Infortmation Technology for knowledge enhancement


Modern developments in information and communication technologies (ICT)  provides exciting possibilities to enhance the quality of education. Interactive education software , open access digital libraries, and cheaper and more intuitive technology may facilities new forms of interaction between students, teachers, education employees and the community and enhance the quality of education by making it more accessible.


Information Technology had the capacity to enhance the learning process and facilities communications within education institutions and between educators and learners but it must be used in education institutions under the supervision of qualified well-trained professionals with the expertise in pedagogy and in education to ensure that its impact does not damage or undermine the learning process or the development of learners.


Internet Access

Internet Access is the process that enables individuals and organizations to connect to the Internet using computer terminals, computers, mobile devices, sometimes via computer networks. Once connected to the Internet, users can access Internet services, such as email and the World Wide Web. Internet service providers (ISPs) offer Internet through various technologies that offer a wide range of data signalling rates (speeds).


The Internet provides instant availability of vast stores of information in real time. Prior to the availability of the Internet, one seeking education often had to be physically near the information he wished to learn. This involved walking to a school, listening to a teacher and having access to a library. With the Internet , learners have instant access to information on virtually any subject.


The Internet has become a very useful tool to gain access to an ocean of information. It is an opportunity and privilege to be living in an era where the Internet is easily accessible . Teenagers are able to use this valuable resource for completing projects, researching information, to view pictures and videos of places and people at the click of a button.


The Internet has proved to be of immense assistance in the academic area.

Educators and parents should encourage students to use the Internet and guide them to the right resources that are available online. Parents and educators should be aware that the Internet is an open source environment where information of every kind is easily accessible.


Using the Internet in teaching and learning willl enable the teacher to:


  • Access information instantly and present it to the students in an engaging manner using a variety of teaching methodologies.


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  • Provide educational opportunities for students based on their abilities and interests and different learning styles.


  • Model the safe and responsible use of the Internet in daily classroom life.


  • Access classroom-ready resources suitable for the curriculum and assessment.


  • Communicate with peers and subject experts and overcome the isolation of a classroom.


  • Create and share learning resources and extend learning  outside the classroom.


  • Avail of online continuing professional development courses.


Using Website

One of the most common reasons for us to be hanging around on the Internet every day is the abundance of information it is loaded with . The information is generated by multiple sources and is carefully organized in the form of files and web pages, which, when grouped together to form  a single entity, become a website.


There are several education related websites available on the Internet from which students can benefit greatly. These websites help students in developing their mathematical skills, vocabulary skills, digital resources provided by world renowned educators and experts. Parents and educators should make the best use of the resources available on the Internet to support the educational development of their children. The following are some of the education related websites- Wikipedia, MIT Open Courseware, TED-Ed, Science Net Links, Coursera, Vocabulary.com etc.



Using Search Engines


searchengine is a set of programs which are used  to search for information within a specific realm and collate that information in a database. Search engines help people to organize and display information in a  way which makes it readily accessible. Search engines allow people to access online information on the Web. 

As such, search engines provide great benefits to individuals, organizations, and society. The world Wide Web is different from anything we have known. Considering the amount of information that’s available from a good search engine, it’s similar to having the Yellow pages, a guide book and a road map all in one . Search engines can provide much more information than just the URL of a Web site.


search engine is a searchable database which collects information on web pages from the Internet, and indexes the information and then stores the result in a huge database where it can be quickly searched. The search engine then provides an interface to search the database.


The lives of teacher, professors and students are hard enough as it is with demanding hours, straining subject matter and endless research. There are many great search engines that can ease the strain of these pressure.

Examples: Google, Alta Vista, Yahoo.


Communicating with Experts


For teachers, the Internet is an electronic gateway to learning resouces and experiences Otherwise unavailable;  no matter how specialized an area of interest may be , there is someone on the Internet who shares the interest and has identified or developed useful resources.  It is through interaction with other people, ideas , and new experiences that we all construct new knowledge, and the power of the Internet in its capacity to enable interactions with people over great distances and link people with  distant informational resources . In essence, the Internet provides a way to break out of the school walls and engage students with people and resources scattered around the  world. There are times when each of us needs help finding specific information, learning new concepts, completing assignments, or making plans. On the web, personal assistance is only a click away.

Accessing CD-ROM and DVDs

            The CD-ROM format  is a popular medium for software, music, and data file. CD-ROM and DVDs has the ability to store sound files , graphics, video sequences. The two major differences between CD-ROM and DVD are that DVD has a much higher capacity for storing data (between 4Gb and 7Gb ) and the data can be accessed at very high speeds. This makes it a versatile medium capable of interactive use

Students using this type of learning tool are able to work at their own pace and capability. Having access to the Internet has created new tools for software developers and by combining CDs and DVDs along with an Intranet the resources can be used over the whole of a networked environment; this in turn helps teachers who are not computer literate and who are not able to solve computer operating problems.


DVD-ROM resources are motivating for students . DVD technology opens a visual window to content far richer than print. DVD-ROM s transform educational content into an engaging world of stories, facts, ideas , pictures, and sounds that students can actively explore. The active engagement the DVD-ROMs offer students is educationally crucial, particularly in the “computer game” era. Additionally , DVD resources make teachers better able to deliver information using the kids of media that mirror how students really think and learn. The versatile variety of media available on a DVD-ROM is particularly valuable, since teachers can’t always know up front which approach will work for each student. DVD-ROMs also free the teacher from the primary responsibility of delivering information , providing increased opportunities to facilitate, encourage, discuss and mentor.


Technology has filtered into education fairly slowly and in order for the CD-ROM DVD to continue as a viable means in instructional use, educators must maximise it to its full potential and become confident in using the  applications.


Accessing Digital Content

Digital content is any type of content that exists in the form of digital data. Digital content comes in many forms, from text (e-books) and audio and videos files (training videos, tutorials etc.) , to graphics animations, and images. Typically , digital content refers to information available for download or distribution on electronic media.

Increasingly, teachers all over the world are using technology, including digital curricular resources and tools, to enhance students’ classroom experiences and improve learning outcomes.

 Recognizing student needs, interests, and preferences, teachers employ digital content to transform their instructional practices, including , in some cases, by independently creating, modifying, and sharing learning materials. Empowering teachers to engage in the development, refinement, and use of digital materials- including lesson plans, videos of instructional practice , and formative assessments- holds real promise for improving student learning experiences and teacher effectiveness. 

Unlike traditional textbooks and other printed materials, digital content can be updated in a more timely manner and better targeted to meet specific student needs –enabling and stimulating flexibility, creativity, and collaboration and allowing for an educator-influenced system of ongoing improvement and enhancement.


Using E-Books


E-Books can present any type of auditory or visual  materials-including speech, text, music, animations, photographs, or videos- alone or in different combinations. E-Books can link different types of representations such as pictures with sounds, oral readings with written text, videos with subtitles, or any other combinations that could reinforce teaching. Teachers should proactively make use of e-Books in facilitating teaching and learning. The usage of such, from the perspective of teachers, involves in the preparation or even the development of eBooks for students.


Using E-tutorials and training videos


E-tutorials and training videos help in the overall professional development of the teachers. With the help of E-tutorials teachers will be able to keep themselves up to date with new innovation and techniques in the field of teaching. Teachers may get better guidance and teaching tips from the  experts and teacher educators in E-tutorials. Training videos can in turn help the teachers in developing effective classrooms, improving their teaching techniques and style.


Use of Information Technology for Teachers


Gurukul system of Education was in vogue in India. The main characteristics of Gurukul System were dedicated and knowledgeable teachers, individualized and learner centre teaching, and self-motivated students  eager to learn. This system changed due to increase in number of students. Consequently, the number of teachers increased. Some teachers are born but rests of them have to be given rigorous training so as to develop required competency to become a teacher.

 Teachers have been conscious about the quality of their teaching. To enhance the quality, some teachers use teaching aids, like, charts, models – static and working, specimen, slides, etc. because teachers are given training both in preparation and use of Audio-visual Aids. It is a known fact that majority of schools do not have appropriate teaching aids related to the school content. So teachers have no facility to use A – V Aids during teaching. the use of A-V Aids get further restricted due to unmotivated persons becoming teachers. 

Central government realized the need of improving quality of education through the use of Television wherein most competent teacher teaches the topic with the help of most appropriate teaching aids. This helped in improving the quality of teaching in schools having no teacher to teach the subject, less competent teacher, schools having poor or no facility of teaching aids, etc.


Programmes offered through television were produced by different State Institute of Educational Technology (SIET) in different languages. Even the Video Instructional Materials were produced and made available to teachers; still majority of schools did not make use of them. some of the reasons were no facility of TV and VCR, no electricity, TV and VCR not in working condition, not incorporated in the time table, lack of initiation on the part of teacher and Principle , etc.

 Along with A-V Aids, the print media has to  go a long way in improving the quality of teaching and learning. Format in which the textbooks were written was not beneficial for teachers and students. Researchers started thinking and using different Theories of Learning for developing Instructional Material. This gives birth to Programmed Learning Material based on Operant Conditioning  Theory of Learning . Programmed Learning Materials were compared with that of Lecture Method or Conventional Method. 

Programmed Learning Material alone as well as in combination with other methods for teaching different subjects was found to be effective in terms of achievement of students.


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