A computer network is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections between nodes.
A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
A network is defined as a group of two or more computer systems linked together.
Types of Networks
LOCAL AREA NETWORK(LAN)
CAMPUS AREA NETWORK(CAN)
METROPOLITAN AREA NETWORK(MAN)
WIDE AREA NETWORK(WAN)
LOCAL AREA NETWORK-:
Local area network is a group of computers connected with each other in a small places such as school, hospital, apartment etc.
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building.
CAMPUS AREA NETWORK(CAN)-:
A Campus Are Network are use to connect multiple building labs or network within a limited area. for example University have multiple department with in their campus. and each department have multiple computer labs. now we need to connect all building labs of the university campus. in this case we can establish a campus area network.
METROPOLITAN AREA NETWORK(MAN)-:
It connects two or more computers that are belongs in the same or different cities. Metropolitan Area Network are use to establish connection between multiple computer network with in the same city or two different city network.
Example-: to establish a connection between all networking device of all branch that are exist within a city.
WIDE ARE NETWORK(WAN)-:
Wide area network provides long distance transmission of data. The size of the WAN is larger than LAN and MAN. A WAN can cover country, continent or even a whole world. Internet connection is an example of WAN. Other examples of WAN are mobile broadband connections such as 3G, 4G etc.
Important Components/terms used in networking
Node-: when a computer is connect with any network then it id called Node.
Client-: when a computer request to access any resource to any other computer then it is called Client.
Server-:when a computer accept the request of client computer and gives their response then it is called Server.
a protocol is a set of rules that allow networking devices(computer) to communicate with each other.
Protocol, in computer Network, a set of rules or procedures for transmitting data between electronic devices, such as computers.
A protocol is a set of rules and guidelines for communicating data. Rules are defined for each step and process during communication between two or more computers. Networks have to follow these rules to successfully transmit data.
It is a digital language through which we communicate with others on the Internet. protocol meaning is that it a set of mutually accepted and implemented rules at both ends of the communications channel for the proper exchange of information.
Switching techniques are used for transmitting data across networks. there are three types of switching techniques are:
Circuit Switching-: In this technique, before sending and data from source to destination, a physical connection establish first and after establish the connection data will transfer. the advantages of Circuit Switching are to setup an end to end connection between computer before any data can be send.
Message Switching-: In this technique, the sender and receiver are not directly connected. There are a number of intermediate nodes transfer data and ensure that the message reaches its destination.
Message switching was a technique developed as an alternate to circuit switching.
Packet Switching-: In this technique,Packet switching is a method of transferring the data to a network in form of packets. In order to transfer the file fast and efficient manner in a network, the data is broken into small pieces of variable length, called Packet. At the destination, all packets has to be reassembled, belonging to the same file.
Network Topology refers to the layout of a network and how different nodes in a network are connected to each other and how they communicate. Topologies are either physical (the physical layout of devices on a network) or logical (the way that the signals act on the network media, or the way that the data passes through the network from one device to the next).
Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial field buses and computer networks.
There are five type of common network topologies.
BUS or Linear Topology
Ring or Circular Topology
Star Topology: In a star network device are connected to a central computer, called a hub. Nodes communicate across the network by passing data through the hub.
Advantage: In a star network, one malfunctioning node doesn't affect the rest of the network.
Disadvantage: If the central computer fails, the entire network becomes unusable
Bus Topology: it is also non as liner Topology, In Bus Topology it connect all nodes with in a single length of transmission medium.
In Bus Topology it Consists of a single length of transmission medium (normally coaxial cable) onto which the various nodes are attached. This topology is used in traditional data communication network.
Advantage: It's easy to connect a computer or device and typically it requires less cable than a star topology.
Disadvantage: The entire network shuts down if there is a break in the main wire and it can be difficult to identify the problem if the network shuts down.
Ring Topology: A local-area network (LAN) whose topology is a ring. That is, all of the nodes are connected in a closed loop. Messages travel around the ring, with each node reading those messages addressed to it.
Advantage: One main advantage to a ring network is that it can span larger distances than other types of networks, such as bus networks, because each node regenerates messages as they pass through it.
Tree Topology: This is a "hybrid" topology that combines characteristics of linear or bus and star topologies. In a tree network, groups of star-configured networks are connected to a linear bus backbone cable.
Advantage: A Tree topology is a good choice for large computer networks as the tree topology "divides" the whole network into parts that are more easily manageable.
Disadvantage: The entire network depends on a central Device(hub,switch,router) and a failure of the central device can cripple the whole network.
Network Devices (Hub, Repeater, Bridge, Switch, Router, Gateways)
Repeater-: A repeater operates at the physical layer. Its job is to regenerate the signal over the same network before the signal becomes too weak or corrupted so as to extend the length to which the signal can be transmitted over the same network. An important point to be noted about repeaters is that they do not amplify the signal. When the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength. It is a 2-port device.
Hub-: A Hub is a device that connects a number of computers together to make a Network. A hub is centralized networking device. It is used to connect multiple computer in a network. All the computer directly connects with Hub ports. for example, the connector in star topology which connects different computer.
A Hub is not a smart device because it cannot filter data, so data packets are sent to all connected devices.
There are two type of Hub
Active Hub: - These are the hubs which have their own power supply and can clean, boost and relay the signal along with the network. It serves both as a repeater as well as wiring center. These are used to extend the maximum distance between nodes.
Passive Hub:- These are the hubs which collect wiring from nodes and power supply from active hub. These hubs relay signals onto the network without cleaning and boosting them and can’t be used to extend the distance between nodes.
Bridge-: A bridge is a networking device that is used to connect two different types of network. When we need to connect a computer with more than one network then we can use bridge to connect to different network on the same time.
Switch-: A switch is a centralized device that connects a number of computers together to make a Local Network. It is a more intelligent device compare to HUB because it does not provide collision. If it receives a message from any computer then it checks first and it directly send the data with their destination computer. It does not broadcast the data and only send it to that specific computer. Because of this, network that use switches are more secure and safe compare to a HUB Network.
A router has a lot more capabilities than other network devices, such as a hub or a switch that are only able to perform basic network functions. For example, a hub is often used to transfer data between computers or network devices, but does not analyze or do anything with the data it is transferring. By contrast, routers can analyze the data being sent over a network, change how it is packaged, and send it to another network or over a different network. For example, routers are commonly used in home networks to share a single Internet connection between multiple computers.
Gateway-: a gateway is a networked device which serves as an entry point into another network. For example, a wireless router is commonly the default gateway in a home network.