Introduction To Computer Networks
present day international scenario is ever changing. statistics conversation and community have changed the way business and different every day affair works. Now, they highly depend upon laptop networks and internet work.
a set of devices often mentioned as nodes connected by using media link is known as a network.
A node can be a device that is able to sending or receiving facts generated through different nodes on the network like a laptop, printer and so on. those links connecting the devices are called communique channels.
computer network is a telecommunication channel using which we can share facts with other computer systems or devices, linked to the same community. it’s also called statistics network. The quality example of laptop network is internet.
Computer network does not mean a system with one Control Unit connected to multiple other systems as its slave. That is Distributed system, not Computer Network.
A network must be able to meet certain criterias, these are mentioned below:
Computer Networks: Performance
It can be measured in the 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 :
>>Efficiency of software
>>Number of users
>>Capability of connected hardware
Computer Networks: Reliability
It decides the frequency at which network failure take place. More the failures are, less is the network’s reliability.
Computer Networks: Security
It refers to the protection of data from any unauthorised user or access. While travelling through network, data passes many layers of network, and data can be traced if attempted. Hence security is also a very important characteristic for Networks.
Properties of a Good Network
Interpersonal Communication: We can communicate with each other efficiently and easily. Example: emails, chat rooms, video conferencing etc, all of these are possible because of computer networks.
Resources can be shared: We can share physical resources by making them available on a network such as printers, scanners etc.
Sharing files, data: Authorised users are allowed to share the files on the network.
Basic Communication Model
A Communication model is used to exchange data between two parties. For example: communication between a computer, server and telephone (through modem).
Basic Communication Model
Communication Model: Source
Data to be transmitted is generated by this device, example: telephones, personal computers etc.
Communication Model: Transmitter
The data generated by the source system is not directly transmitted in the form its generated. The transmitter transforms and encodes the data in such a form to produce electromagnetic waves or signals.
Communication Model: Transmission System
A transmission system can be a single transmission line or a complex network connecting source and destination.
Communication Model: Receiver
Receiver accepts the signal from the transmission system and converts it into a form which is easily managed by the destination device.
Communication Model: Destination
Destination receives the incoming data from the receiver.
The exchange of data between two devices through a transmission medium is called 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 a part of a communication system. Data Communication has two types – Local and Remote which are discussed below:
Data Communication: Local
Local communication takes place when the communicating devices are in the same geographical area, same building, or face-to-face etc.
Data Communication: Remote
Remote communication takes place over a distance i.e. the devices are farther. The effectiveness of a data communication can be measured through the following features :
Delivery: Delivery should be done to the correct destination.
Timeliness: Delivery should be on time.
Accuracy: Data delivered should be accurate
Components of Data Communication
Message: It is the information to be delivered.
Sender: Sender is the person who is sending the message.
Receiver: Receiver is the person to whom the message is being sent to.
Medium: It is the medium through which the message is sent. For example: A Modem.
Protocol: These are some set of rules which govern data communication.
A computer network is a system in which multiple computers are connected to each other to share information and resources.
Characteristics of a Computer Network
Share resources from one computer to another.
Create files and store them in one computer, access those files from the other computer(s) connected over the network.
Connect a printer, scanner, or a fax machine to one computer within the network and let other computers of the network use the machines available over the network.
Following is the list of hardware’s required to set up a computer network.
>>Internal Network Cards
>>External Network Cards
Network cables are used to connect computers. The most commonly used cable is Category 5 cable RJ-45.
A computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work.
The solution is to use a central body to which other computers, printers, scanners, etc. can be connected and then this body will manage or distribute network traffic.
A router is a type of device which acts as the central point among computers and other devices that are a part of the network. It is equipped with holes called ports. Computers and other devices are connected to a router using network cables. Now-a-days router comes in wireless modes using which computers can be connected without any physical cable.
Network card is a necessary component of a computer without which a computer cannot be connected over a network. It is also known as the network adapter or Network Interface Card (NIC). Most branded computers have network card pre-installed. Network cards are of two types: Internal and External Network Cards.
Internal Network Cards
Motherboard has a slot for internal network card where it is to be inserted. Internal network cards are of two types in which the first type uses Peripheral Component Interconnect (PCI) connection, while the second type uses Industry Standard Architecture (ISA). Network cables are required to provide network access.
External Network Cards
External network cards are of two types: Wireless and USB based. Wireless network card needs to be inserted into the motherboard, however no network cable is required to connect to the network.
External Network Card
Universal Serial Bus (USB)
USB card is easy to use and connects via USB port. Computers automatically detect USB card and can install the drivers required to support the USB network card automatically.