Computer network is collection of Computers and other hardware interconnected by communication channels that allow sharing of resources and information. where at least one process in a device is able to send or receive data two or form at least one process residing in a remote device, then two device are said to be in a network.
Features of Computer Network:
The features of computer network are as follows:
- Computer networks facilitates communication efficiently through e-mail, instant messaging, chat video calls etc.
- It permits information sharing of files, data or other types of information stored on the computer in a network.
- It shares network and computing resources such as I/O devices memory or processor among the computers which are connected through the network.
- It may be increase as it may be used by hackers to deploy the computer viruses on the devices connected to the network.
- may be difficult to set up and it may be very costly to set up an effective network in a large organization or company.
- computer network are quite flexible because all of its topology and networking strategies support addition for extra components or terminal to a network.
- They are reliable because if one of the attached system in the network collapse or fail, then same data can be gathered from another system attached to the network.
Applications of computer Network:
Here the some application of computer network:
- video conferencing: It is possible for business organization or people to call the live video conferencing for real time communication for important meeting, discussions or personal purpose.
- Internet Service: They provide internet service over the entire network and world wide web which contains variety of information and also involves interaction between users and remote database.
- Broadcasting: with use of computer networks, news and important messages can be broadcasted just in few seconds which saves time and effort of work.
- E-commerce (electronic commerce): Through the use of computer network many people pay bills, manage bank accounts and handle investments electronically.
- File sharing: They can also be use for sharing files, videos, audios, image over the computer network very efficiently.
Types of Topology in Computer network
A network configuration is also called as network topology. A network topology is a shape or physical connectivity of a network. Its refers to physical layout of computers (servers and workstations) and cabling or connections between them on a network.
The most common network topologies are:
- Bus topology
- star topology
- Ring topology
- Mesh topology
- Tree topology
In Bus topology all the clients including server are attached with single bus or cable. The Bus acts as backbone for the network. BNC (British Network Cable) or T- connector is used to connect the terminals with the Bus.
Advantages Bus Topology
i) Easy to connect a computer or peripheral to a linear Bus or cable.
11) Requires less cable length and thus is less costly.
Disadvantages Bus Topology
- Entire Network shuts down if there is break in the main cable.
- Difficulty to identify the problem if the entire network shuts down.
- Minimum chance for data collisions when more than One client want to access same resources the same time. So the performance decreases.
A star topology is designed with each node (servers, work stations and peripherals) connected directly to a centrally located device called as network device i.e. hub or Switch. Data on star topology passes through the central device before continuing to its destination. The hub or switch manages and controls all the functions or activities on the network. This topology is more expensive due to the requirements of more number of cables and other controlling devices like switch.
Advantage of star topology
- Easy in installation and cabling.
- No disruption in the network when connecting or removing device.
- Easy to detect faults and remove the parts.
Disadvantages of star topology
- Requires more cable length than (bus) topology.
- if the hub or switch fails, the nodes attached also fails and network failure occurs.
- More expensive because of the additional cost of networking. device like switch or hub and cables.
In this topology, each device is attached to the other device in the network in a ring like Structure. The cabling runs from one System to another without any end point forming a loop called ring. The ring topology pass data in one direction.
Advantages Ring topology
Networking device like switch or hub is not required.
Advantages: No use of networking device less costly comparatively.
Disadvantages Ring topology
- The failure of one nodes can also affect the whole network.
- Failure in one of the cable can also affect the network.
- Adding or removing the devices from the network is difficult.
Tree Topology (Hierarchical)
A tree (hierarchical) topology is similar to star topology because several clients are Connected to the central host computer or a central networking device. However, these client computers also serve as host computers to the next level of units. Typically, the host computer at the top of the hierarchy is the mainframe computer and lower levels of hierarchy could consist of mini computers or micro computer. Tree topology may have characteristics of star topology, ring topology or bus topology.
Advantages tree topology
- Point-to-point wiring for individual segments.
- Expansion of network is possible and easy.
- If one segment is damaged, other segments are not affected.
- Error detection & Correction is easy.
Disadvantages Tree topology
- It the backbone line breaks, the entire segment goes down.
- More difficult in configuring and wiring than other topology
- Overall length of each segment is limited by the type of cable used.
Mesh topology is net like network communication in which there are at least to two pathways to each node. In mesh topology, every computer is connected to each other by point-to-point connections. In this topology, one or more computers become switching center interlinking Computers with others. The damage of one or more cables in the network may not have vital impact on other nodes except the involved computers.
Advantages of mesh topology
- It is very reliable because any link failure will affect only direct Communication between the nodes Connected by that link.
- Each node in the network need not have individual routing Capability.
- Communication is very fast between any two nodes.
Disadvantages of mesh topology
- It is the expensive network topology with the link cost point of view because cost of linking system grows with the Square of number of nodes.
Types of computer Network
The different types of computer network like LAN, MAN and WAN are discuss below:
LAN (Local Area Network)
- In LAN the geographical distribution of nodes (computers) is limited to few kilometers.
- The purpose of LAN Is to enable the communication among computing devices within a building or office of an organization.
- In LAN Cable the communication channels like twisted pair. Co-axial cable are used for transmission of data –
- This type of network is owned by a single organization for their own use.
- The cost of Communication and networking is low comparative.
- the use network topologies like bus, star and ring. most commonly.
MAN (Metropolitan Area Network)
- In MAN, the geographical distribution of nodes (computers) is limited few tens of kilometers.
- It’s main purpose is to interconnect the LANs located in a city or metropolitan area.
- The type of communication channel used in this network can be fiber optics, telephone lines, microwave etc.
- The interconnected LANs in this type of network generally belongs to a single organization which manages or controls the network
- The cost of communication and networking is medium comparatively.
- It uses the Network topologies like star, mesh, tree, hybrid etc.
WAN (wide Area Network)
- In WAN, the geographical distribution of nodes (computers) may extend up-to thousands of kilometers.
- It’s main purpose is to interconnect the LANs spread over several cities and countries all over the world.
- The type of communication channel used in this network can be fibre optics, telephone lines, microwave, satellite channel etc.
- The interconnected LANs in this type of Network generally belongs to a single organization or multiple organizations.
- The cost of communication and networking is highest in comparison to other networks.
- It uses the network topologies like star, mesh tree. hybrid etc.
Networking Devices in computer network
Here the some Networking Device like Network Interface Card (NIC), Switches, Router, Bridge, Repeaters are discuss below:
Network Interface Card (NIC) in computer network
The NIC is a circuit board that is inserted in the slot of motherboard. It provides the physical connection between network cable and the computer. NICS are the major factor for determining the speed and performance of the network.
Switches in computer network
A concentrator or a switch is a device that provide a central connection point for workstations, cables, servers and peripherals. In star topology, the twisted pair cable is run from each workstations to a central device called as switch or hub. Switches are usually 8, 12 or 24, RJ-45 ports.
Router in computer network
A router translates the information from one network to another. And is similar to an intelligent bridge Routers select the best path to route a message based the destination address and the origin. The router can direct traffic to prevent head-on collisions and is smart enough to know when to direct a traffic along back roads and shortcuts.
Bridges in computer
A bridge is a device that allows to segment a large network into smaller and more efficient networks. A bridge monitors information traffic on the both sides of the network So that it can pass packets of information to the correct destination.
Most bridges “listen to the network and automatically figure out the address of each sides of the bridge. The bridge can inspect each message and if necessary broadcast it to the other side of the network.
Repeaters in computer network
A repeater is a networking device that receives a signal and retransmits it at a higher level or higher power onto the other side so that the signal can longer distances. A repeater amplifies or increases the signal strength.
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