Computer Network Topology (Notes)

Computer Network - Types and Topologies

A computer network is a group of computers that are connected to each other for the purpose of communication. It is a combination of hardware and software resources which allows computers to communicate with many computers and share information between computing devices.

Components of Network

• Server - The computers that provide shared resources to network users.
• Receiver - The computers that access the shared resources provided by server.
• Medium - The wires which makes the physical connections.

TYPES OF COMPUTER NETWORK

(1) Local Area Network (LAN) - It is a computer network that covers a small geographical area like home,office or small group of buildings.

• It is small in size and generally owned by private body.
• It covers maximum ratings of 10 km.
• Data transfer rates are high.
• Two or more computing devices are connected by physical media such as transmission cable
• LAN is based on Ethernet Technique.

(2) Wide Area Network (WAN) -  It is a computer network that may covers geographical area of a country or continent. It is use to connect LANs and other types of network together so that users of different locations connect with each other,

• Data transfer rate is relatively slower than LAN.
• WANs are often built using switched circuits.
• The device which connects WAN with several LANs is called router.



(3) Metropolitan Area Network (MAN) - It is a computer network that usually spans a city or large campus. 

• It covers maximum radius of 50 km.
• It usually interconnects a number of LANs into a large network.
• It may be a single network such as Cable TV network, spread over a city.

NETWORK TOPOLOGIES

Network Topologies describes the physical layout i.e. how cables, nodes and connection devices are linked or organised together.

(1) Bus Network Topology - It is network topology in which set of nodes are connected by a single communication line, called a bus. 

• It is simplest way to connect multiple nodes
• At one time only one node can send data across the network
• The failure of one device does not affect the others.

(2) Star Network Topology - In this, all the computers are connected to the central device called Hub.Node send electronics signal to the hub, and then to the remaining computers on the network.

• If Hub will fail then all other computer networks will also fail.
• If only one computer will fail, then it will not affect the other networks.
• It is not so expensive as it requires only one cable to connect more host.

(3) Mesh Network Topology - In this, each node in the network has a connection with other node in the network.

• The cost of this network is high as it requires large amount of cables and each node require hub.
• It is more reliable as there is more than one path between a source and a destination in the network.

(4) Ring Network Topology - It is a network topology each node connects to exactly two other nodes forming  a single continuous pathway for signals through each node like a ring.

• The failure of any node may result in failure of the whole ring network.

Some Network Related Terms

• Protocol - It is set of rules and standards which is used by computers to exchange data or information with each other across a network.
• Nodes - It is a connect point where either data transmission ends or redistribution of data starts.
• Hosts - It is computer or other devices connected to a computer network