Computer network

 Computer network

What is a network:  A Network is a group of multiple computers that are linked together. It is also called a computer network, which is a set of inter-connected computers to share related information in any form, such as text, numbers, images, audio, or video. Some devices, such as printers, are interconnected by a communication link. such as a cable. These devices communicate through a network system that consists of hardware (physical components) and software (programs)

      Type of computer networks

There are many types of Networks that are classified on the basis of various characteristics. which are used to connect computers on the network. The effectiveness of a computer network is measured by four parts: Delivery and accuracy. Timeliness, and Jitter (variation). The different types of networks available are: Local Area Network (LAN). Metropolitan Area Network (MAN). and Wide Area Network (WAN). In the subsequent sections, you learn about LAN, MAN, and WAN.

 

v LAN: LAN is a privately owned network of an organization. It connects a computer with other hardware, such as a printer, at home or in an office. The range of LAN is restricted to a few kilometers only. This type of network is proper when you want to connect two different departments in a building. There are different technologies (such as Ethernet and Token Ring), each with its own advantages and disadvantages. The data transfer rate for LAN technologies is up to 10 Gbit/s High transmission rates are possible in LAN because of the short distances between the various computer networks. This makes LAN a high-speed fault-tolerant data network. LAN enables shared access to devices and applications, file exchange between connected users, and communication between users via electronic mail and other applications

LAN consists of Network Interface Cards (NICs), which are fitted on the expansion slot of the motherboard inside computers: a cable (or an equivalent wireless connection) to connect the computers together, a protocol software to transfer data from one computer to another a user interface software to connect the user to the network: and an operating system software to help a user for sharing resources such as files and printers. LANS with similar architectures are linked by bridges, which act as transfer points, and those with different architectures are linked by gateways, which convert data as it passes between systems in the network. Gateways may link computers by means of cables, optical fibers, or satellites, but users commonly access the networks through a modem (a device that allows computers to communicate over telephone lines). The following are the characteristics of LAN :

v LAN transfers data at high speed LAN's reach is limited.

v LAN’s reach is limited.

v LAN technology is generally less expensive than MAN and WAN.

LAN is a transmission system that allows a large number and a variety of computing devices to exchange information at high speeds, over limited distances. These devices may range from large mainframe systems to personal computers and peripherals (devices). The operating system used by LAN interprets the input and instructs the networked devices, allows users to communicate with each other, share printers and storage devices, and simultaneously access centrally located processors, data, or programs (instruction sets). LAN users may also access other LANS. Due to the complexity of computer communications. LAN protocols are divided into several hierarchical levels. This hierarchical structure is called a protocol stack. LANs have become popular because they allow users to share vital computing resources electronically. Including expensive hardware, such as printers and CD-ROM drives, and application programs. Nowadays. LAN inter-networks are powerful, flexible, and easy to use. but remember that they incorporate several technologies that must work together flawlessly.

MAN

 

MAN is a bigger version of LAN and its technology is also similar to LAN. It provides network coverage between LAN and WAN. In other words, MAN covers an area that is larger than the area covered by LAN but smaller than the area covered by WAN MAN generally connects two or more LANS or Campus Area Networks (CANS). It usually acts as a backbone, connecting several LANS owned by an organization, as well as hiring Internet services to users. MANS contains several protocols (such as FDDI and DQDB), which have their own topology and may have a higher data transfer rate. MAN typically uses wireless infrastructure or optical fiber connections to link its sites. It is generally owned by a group or combination of users or by a single network provider providing the service to the users. It adopts technologies from both LAN and WAN Protocols such as Asynchronous Transfer Mode (ATM). Fiber Distributed Data Interface (FDDI). Distributed Queue Dual Bus (DQDB) and Switched Multi-megabit Data Service (SMDS) are used in MAN. In short, you can say that MAN acts as a high-speed network that allows the sharing of regional resources Apart from the three main types of networks namely, LAN, WAN, and MAN there are other types of networks also available. These include the following :

 

v Personal Area Network (PAN): Provides communication between a person's digital devices such as fax machines, telephones, and PDAs.

 

v Campus Area Network (CAN): Refers to the network spans within a limited geographical area such as a campus or a military base.

 

v Global Area Network (GAN): Provides support for mobile applications across a number wireless LANs, such as satellite coverage areas.

 

v Value Added Network (VAN): Refers to a type of network where a communication channel is hired by a company to facilitate Electronic Data Interchange (EDI) or provide other network services. Virtual Private Network (VPN): Provides links between various nodes with the help of open connections or virtual circuits.

 

 

v Wireless/Mobile Networks: Refers to the transmission media such as infrared light, radio channels, microwave radio cellular telephone systems, and satellite relays, here the transmission rates vary with the media. from under 1 Mbit/s up to the 1Gbit/s range for satellite relays

 

 

WAN

 

WAN is a type of network used to cover a wide geographical area or region. WANs can be interconnected with LANS. WAN links different metropolitans: countries and national boundaries, thereby enabling easy communication. A WAN may be located entirely within a state or country, or it may be interconnected around the world. Several protocols (X.23 TCP/IP. Frame Relay) are available for WAN The transfer rate of these protocols is around 1Mbit or less and they often use public telephone networks or leased transmission lines.

The following are the characteristics of WAN :

1. v OWAN exists in an unlimited geographical area
2. v WAN is more susceptible to errors due to the distances involved.
3. v WAN interconnects multiple LANs.
4. v E WAN is more sophisticated and complex than LAN’s.
5. v WAN technology is expensive.

WANs can further be classified into two categories :

ü Enterprise WANs: Connects computer resources of a single organization that are located at great distances An organization that needs to perform computer operations at several distant sites can employ an enterprise WAN to interconnect the sites. An enterprise WA can use a combination of private and commercial network services but is dedicated to the needs of a particular organization.

 

ü Global WANs: Interconnects the networks of several corporations and organizations. It is seen that WANs are often a natural choice when connecting geographically separated LANS into a single network. Much of the complexity and expense of operating WAN is due to the great distance that the signal must travel to reach the interconnected sites. WAN links an often slower and typically depend on a public transmission medium hired from a communication service provider. The most common example of WAN is the Internet Let's now learn about the Internet and Intranet.

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