Introduction To Computer Networks – What is A Network ,Definition

Introduction To Computer Networks – What is A Network ,Definition

Introduction To Computer Networks - What is A Network ,Definition

A set of devices often mentioned as nodes connected by media link is called a Network. A node can be a device which is capable of sending or receiving data generated by other nodes on the network like a computer, printer etc. These links connecting the devices are called Communication channels.

Computer network is a telecommunication channel through which we can share our data. It is also called data network. The best example of computer network is Internet. Computer network does not mean a system with control unit and other systems as its slave. It is called a distributed system

A network must be able to meet certain criteria, these are mentioned below:

  1. Performance
  2. Reliability
  3. Scalability

Performance

It can be measured in following ways :

  • Transit time : It is the time taken to travel a message from one device to another.
  • Response time : It is defined as the time elapsed between enquiry and response.

Other ways to measure performance are :

  1. Efficiency of software
  2. Number of users
  3. Capability of connected hardware

Characteristics of a Computer Network

The following characteristics should be considered in network design and ongoing maintenance:

  • Availability.-Availability is typically measured in a percentage based on the number of minutes that exist in a year. Therefore, uptime would be the number of minutes the network is available divided by the number of minutes in a year.
  • Cost –includes the cost of the network components, their installation, and their ongoing maintenance.
  • Reliability –defines the reliability of the network components and the connectivity between them. Mean time between failures (MTBF) is commonly used to measure reliability.
  • Security-includes the protection of the network components and the data they contain and/or the data transmitted between them.
  • Speed –includes how fast data is transmitted between network end points (the data rate).
  • Scalability –defines how well the network can adapt to new growth, including new users, applications, and network components.
  • Topology –describes the physical cabling layout and the logical way data moves between components.

Types of Networks

Organizations of different structures, sizes, and budgets need different types of networks. Networks can be divided into one of two categories:

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  • peer-to-peer
  • server-based networks

Peer-to-Peer Network

  • A peer-to-peer network has no dedicated servers; instead, a number of workstations are connected together for the purpose of sharing information or devices.
  • Peer-to-peer networks are designed to satisfy the networking needs of home networks or of small companies that do not want to spend a lot of money on a dedicated server but still want to have the capability to share information or devices like in school, college, cyber cafe

Server-Based Networks

  • In server-based network data files that will be used by all of the users are stored on the one server.
  • With a server-based network, the network server stores a list of users who may use network resources and usually holds the resources as well.
  • This will help by giving you a central point to set up permissions on the data files, and it will give you a central point from which to back up all of the data in case data loss should occur.

Network Communications

  • Computer networks use signals to transmit data, and protocols are the languages computers use to communicate.
  • Protocols provide a variety of communications services to the computers on the network.
  • Local area networks connect computers using a shared, half-duplex, baseband medium, and wide area networks link distant networks.
  • Enterprise networks often consist of clients and servers on horizontal segments connected by a common backbone, while peer-to-peer networks consist of a small number of computers on a single LAN.

Different Types of Networks – LAN, WAN , MAN Etc

  1. Local Area network
  2. Wide Area network
  3. Metropolitan Area Network
  4. Campus Area Network
  5. Wireless Local Area Network
  6. System Area Network
  7. Storage Area Network

Data Communication – What is the process of Data Communication 

The exchange of data between two devices through a transmission medium is Data Communication. The data is exchanged in the form of 0’s and 1’s. The transmission medium used is wire cable. For data communication to occur, the communication device must be part of a communication system. Data Communication has two types Local and Remote which are discussed below :

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Local :Data Communication

Local communication takes place when the communicating devices are in the same geographical area, same building, face-to-face between individuals etc.

Remote :Data Communication 

Remote communication takes place over a distance i.e. the devices are farther. Effectiveness of a Data Communication can be measured through the following features :

  1. Delivery : Delivery should be done to the correct destination.
  2. Timeliness : Delivery should be on time.
  3. Accuracy : Data delivered should be accurate.

Components of Data Communication

  1. Message : It is the information to be delivered.
  2. Sender : Sender is the person who is sending the message.
  3. Receiver : Receiver is the person to him the message is to be delivered.
  4. Medium : It is the medium through which message is to be sent for example modem.
  5. Protocol : These are some set of rules which govern data communication.