What Is Computer Network? – It is a collection of two or more computers, which are connected togethar to share information and resources. Computer network is a combination of hardware and software that allows communication between computers over a network.
Benefits of Computer Networking
some of the benefits of network are discussed below:-
- File Sharing :- Networking of computer helps the users to share data files.
- Hardware Sharing :- Users can share devices such as printers, scanners, CD-ROM drives, hard drives, etc.
- Application Sharing :- Applications can be shared over the network and this allows implementation of client/server applications.
- User Communication :- This allows users to communicate using E-Mail, newsgroups video conferencing within the network.
Types Of Computer Network
Computer network is broadly classified into various types:-
Local Area Network (LAN)
LAN is a small and single-site network. It connects network devices over a relatively short distance. It is a system in which computers are distance. It is a system in which computers are interconnected and the geographical area such as home, office, buildings, school may be within a buildings to 1 km.
On most LANs, cables are used to connect the computers. LANs are typically owned, controlled and managed by a single person or organizations. They also use certain specific connectivity technologies, primarily Ethernet and Token Ring. LAN provides a sharing of peripherals in an efficient or effective way.
Wide Area Network (WAN)
A WAN is a geographically dispersed collection of LANs. A WAN like the internet spans most of the world. A network device called a router connects LANs to a WANs. Like the Internet, most WANs are not owned by any one organization, but rather exist under collective or distributed ownership and management. WAN use technology like ATM, Frame Relay and X.25 for connectivity.
Metropolitan Area Network (MAN)
It is a data network designed for a town or city. It connects an area larger than a LAN, but smaller than a WAN, such as a city, with dedicated or high performance hardware.
Its main purpose is to share hardware and software resources by the various users. Cable TV network is an example of Metropolitian Area Network. The computers in a MAN are connected using co-axial cables or fibre optic cables.
Personal Area Network (PAN)
PAN refers to a small network of communication. These are used in a few limited range, which is in reachability of individual person. Few examples of PAN are Bluetooth, Wireless USB, Z-wave and Zig Bee.
Virtual Private Network (VPN)
VPN is a technology that is gaining popularity among large organizations that use the global Internet for both intra-and Inter-organization communication, but require privacy in their intra-organization communication. VPN is a network that is private but virtual.
It is private because it guarantees privacy inside the organization. It is virtual because it does not use real private WANs; the network is physically public but virtually private.
Server :- Server is a system that responds to requests across a computer network to provide a network service. it can be run on dedicated computer it is one of the most powerful and typical computer.
File Server :- File Server is a type of computer used on network that provides access to files. It allows users to share programs and data over network.
Protocols :- Protocols are the set of rules used by a network for communication. it is mainly used to connect all the computer to the network.
These devices are required to amplify the signal to restore the original strength of signal and to provide an inteface to connect multiple computers in a network. There are many types of network devices used in networking.
Some of them are described below:-
It is a device that operates only on the physical layer of OSI Model. Repeaters have two ports and can connect two segments of a LAN. It amplifies the feeble signals when they are trasnported over a long distance so that the signal can be as strong as the original signal. A repeater boosts the signal back to its correct level.
It is like a repeater with multiple ports is used to connect the network channels. It acts as a centralised connection to several computers with the central node or server. When a hub receives a packet of data at one of its ports from a network channel, it transmits the packet to all of its ports to all other network channel.
It is an interconnecting device, which joins two different network protocols together. They are also known as protocol converters. It accepts packets formated for one protocol and converts the formated packets into another protocol.
The gateway is a node in a network which serves as a proxy server and a firewall system and prevents the unauthorized access. it holds the information from a website temporarily, so that the repeated access to same Website or Web Page could be directed to the proxy server instead of actual web server. Thus helps in reducing the traffic load.
It is a small hardware device that joins multiple computers together within one LAN. Switches work on the data link layer of the OSI Model. it helps to reduce overall network traffic.
Switch forwads a data packet to a specific route by establishing a temporary connection between the source and the destination. there is a vast difference between a switch and a hub. A hub forwards each incoming packet (data) to all the hub ports, while a switch forwards each incoming packet to the specified recipient.
It is a hardware device which is designed to take incoming packets, analyse the packets, moving and converting the packets to another network interface, dropping the packets, directing packets to the appropriate locations etc.
It serves a similar function as switches. A Bridge reduce the amount of traffic on a LAN by dividing it into two segments. traditional bridges support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called multiport bridges.
It is a device that converts digital signal to analog signal (modulator) at the sender’s site and converts back analog signal to digital signal (demodulator) at the reciever’s end, in order to make communication possible via telephone lines, A MODEM is always placed between a telephone line and a computer.
The Term ‘topology’ refers to the way a network is laid out, either physically or logically. Topology can be referred as the geometric arrangement of a computer system. Each computer system in a topology is known as node, network topology is determined only by the configuration of connections between nodes. The most commonly used topology are described below:-
it is such that there is a single line to which all nodes are connected. It is usually used when a network installation is small, simple or temporary. In Bus topology, all the network components are connected with a same line. Ethernet is commonly well protocol in networks connected by bus topology.
Advantage of Bus Topology:-
- All the nodes are connected directly, so very short cable length is required.
- The architecture is very simple and linear.
- Bus topology can be extended easily on either sides.
Disadvantages of Bus Topology:-
- In case of any fault in data transmission, fault isolation is very difficult. we have to check the entire network to find the fault.
- Becomes slow with increase in number of nodes.
- The entire network shuts down if there is an error occurs in the main cable.
In This network topology, the peripheral nodes are connected to a central node, which rebroadcasts all transmissions recieved from any peripheral node to all peripheral nodes across the network, including the originating node. A star network can be expanded by placing another star hub.
The protocols used in star topology are Ethernet, Token Ring and Local Talk.
Advantage of Star Topology:-
- Installation of star topology is very easy as all the nodes are directly connected to the central node or server.
- Easy to detect faults and remove it
- Failure of single system will not bring down the entire network
Disadvantages of Star Topology:-
- Requires more cable length than bus topology.
- if hub or server fails, the entire network will be disabled.
- Difficult to expand, as the new node has to connect all the way to central node.
Ring or Circular Topology
This topology is used in high-performance networks where large bandwidth is necessary. The protocols used to implement ring topology are Token Ring and Fibre Distributed Data Interface (FDDI). In ring topology, data is transmitted in form of Token over a network after passing through each node, the data returns to the sending node.
Advantage Of Ring Topology:-
- Short cable length is required.
- Suitable for opticle fibre as the data flow in one direction.
- It is less costly than star topology.
Disadvantage of Ring Topology:-
- Fault diagnosis is very difficult in a network formed using ring topology.
- Failure of single computer affects the whole network
- Adding or removing the computers disturbs whole network activity.
It is also known as completely interconnected topology. In mesh topology. every node has a dedicated point-to-point link to every other node. It provides a bi-directional link between each possible node. This type of network topology contains atleast two nodes with two or more paths between them. Mesh topology is roburst because the failure of any one computer does not bring down the entire network.
Advantage of Mesh Topology:-
- Execellent for long distance networking.
- communication possible through the alternate route. if one path is busy
- its performance is not affected with heavy load of data transmission.
Disadvantage of Mesh Topology:-
- Long wire/cable length, hence increase in the cost of installation and maintenance.
- The hardware required to connect each link is expensive.
This is a network topology in which nodes are arranged as a tree. The function of the central node. in this topology may be distributed. A tree topology is an extension and variation of star topology. Its basic structure is like an inverted tree. Where the root acts as a server. It allows more devices to be attached to a single hub.
Advantages of Tree Topology:-
- The tree topology simulates hierarchical flow of data. So it is suitable for application where hierarchical flow of data and control is required.
- we can easily extend the network.
- If one segment is damaged, other segments are not affected.
Disadvantages of Tree Topology:-
- Long cables are required.
- There are dependables on the root node.
- If the central hub fails, the entire system breaks down.
Models of Computer Network
There are mainly two modules of computer networking.
It is also known as P2P network. This computer network relies on computing power at the edges of a connection rather than in the network itself. It is used for sharing content like audio, video, data or anything in digital format. In P2P connection, a couple of computers is connected via a Universal Serial Bus (USB) to transfer files.
In Peer-To-Peer Networking, each or every computer may be worked as server or client.
The model of interaction between two applications programs in which a program at one end (client) requests a service from a program at the other end (server).
It is a network architecture which seperates the client from the server. It is scalable architechture. Where one computer works as server and others as client. here, client acts as the active device and server behaves as passively.
Terms Related To Network
- Multiplexing – It is a technique used for transmitting signals simultanously over a common medium. It involves single path and multiple channels for data communication.
- Code Division Multiple Access (CDMA) – It is a channel access method used by various radio communication technologies. CDMA employs spread spectrum technology and a special coding scheme, where each transmitter is assigned a code to allow multiple users to be multiplexed over the same physical channgel.
- Packet Switching – It refers to method of digital networking communication that combined all transmitted data regardless of content, type or packets. Each packet has header information abouth the source, destination, packet numbering. etc.
- Public Switched Telephone Network (PSTN) It is designed for telephone, which requires modem for data communication. it is used for FAX machine also.
- Integrated Services Digital Network (ISDN) It is used for voice, video and data services. It uses digital transmission and combines both cirucuit and packet switching.
- Ethernet It is a widely used technology employing a bus technology. An ethernet LAN consists of a single co-axial cable called Ether. It operates at 10 Mbps and provides a 48-bits address. Fast Ethernet operates at 100 Mbps.
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