Network

A network is a set of technologies - including hardware, software, and media that can be used to connect computers together, enabling them to communicate, exchange information, and share resources in real time. A network can be one computer connected to the Internet, or two or more computers connected to each other (and possibly to the Internet as well). In a wireless (WiFi) network, the computers are connected by radio signals instead of wires or cables. Advantages of wireless networks include mobility and the absence of unsightly wires. Disadvantages can include a slower connection speed than a wired network and interference from other wireless devices, such as cordless phones.

In others words, network is a system of interconnected computers that communicate with another and share applications, data, and hardware components. It is the act of connecting computers together in order to permit the transfer of data and programs between users.

All networks require hardware, software, and media such as wires to connect systems together. Networks allow many users to access shared data and programs almost instantly. When data and programs are stored on a network and are shared, individual users can substantially reduce the need for programs on their own computers. Networks open up new ways to communicate, such as e-mail and instant messaging. By allowing users to share expensive hardware resources such as networks, printers reduce the cost of running an organization.

Types of Networks

1.  Local Area Networks (LANs) – Local Area Networks (LAN) is a data communication system consisting of several devices such as computers and printers. This type of network contains computers that are relatively near each other and are physically connected using cables, infrared links, or wireless media. A LAN can consists of just two or three PCs connected together to share resources, or it can include hundreds of computers of different kinds. Any network that exists with a single building, or even a group of adjacent buildings, is considered a LAN. A LAN is not a system that connects to the public environment (such as the Internet) using phone or data lines. It is often helpful to connect separate LANs together so they can communicate and exchange data. In a large company, for example, two departments located on the same floor of a building may have their own separate LANs, but if the departments need to share data, then they can create a link between the two LANs.

2. Wide Area Networks (WANs) – A Wide Area Networks (WAN) is two or more LANs connected together, generally across a wide geographical area. For example, a company may have its corporate headquarters and manufacturing plant in one city and its marketing office in another. Each site needs resources, data and programs locally, but it also needs data to share with the other sites. To accomplish this feat of data communication, the company can attach devices that connect over public utilities to create a WAN.

These remote LANs are connected through a telecommunication network or via internet through a Internet service provider (ISP) that contracts with the telecommunication networks to gain access to the Internet’s backbone.

3. Metropolitan Area Networks (MANs) – The Metropolitan Area Networks (MAN) is a large- scale network that connects multiple corporate LANs together. MANs usually are not owned by a single organization; their communication devices and equipment are usually maintained by a group or single network provider that sells its networking services to corporate customers. MANs often take the role of a high - speed network that allows for the sharing of regional resources. MANs also can provide a shared connection to other networks using a WAN link.

Network Topologies and Protocols

An important feature of any LAN is its topology – the logical layout of the cables and devices that connect the nodes of the network. Network designers consider several factors when deciding which topology or combination of topologies to use: the type of computers and cabling (if any) in place, the distance between computers, the speed at which data must travel around the network, and the cost of setting up the network.

Data moves through the network in a structure are called packets.

A network’s topology and related technologies are important for two reasons. First, a correctly designed network, using the most appropriate topology for the organization’s needs, will move data packets as efficiently as possible. Second, the network’s topology plays a role in preventing collisions, which is what happens when multiple nodes try to transmit data at the same time. Their packet can collide and destroy each other.

Bus Topology – A bus topology network uses one cable. All the nodes and peripheral devices are connected in a series to that cable. A special device, a terminator, is attached at the cable’s start and end points, to stop network signals so they do not bounce back down the cable. This topology’s main advantage is that it uses the least amount of cabling of any topology. In a bus topology network, however, extra circuitry and software are used to keep data packets from colliding with one another. Broken connection can bring down all or part of a network.

Star Topology –The star topology is probably the most common topology. In a star network, all nodes are connected to a device called a hub and communicate through it. Data packets are travel through the hub and are sent to the attached nodes, eventually reaching their destinations. Some hubs – known as intelligent hubs – can monitor traffic and help prevent collisions. In a star topology, a broken connection between a node and the hub does not affect the rest of the network. If the hub is lost, however, all nodes connected to that hub are unable to communicate.

Ring Topology – A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring. The network is dependent on the ability of the signal to travel around the ring

The ring topology connects the network’s nodes in a circular chain, with each node connected to the next. The last node connects to the first, completing the ring. Each node examines data as it travels through the ring. If the data – known as token – not addressed to the node examining it, that node passes it to the next node. There is no danger of collision because only one packet of a data travels the ring at a time. If the ring is broken, however, the entire network is unable to communicate.

Mesh Topology – The mesh topology is the least – used network topology and the most expensive to implement. In a mesh environment, a cable runs from every computer, if we have four computer, we must have six cables – three coming from each computer to the other computers. The big advantage to this arrangement is that data can never fail to be delivered, if one connection goes down, there are other ways to route the data to its destination

The Advantages (Benefits) of Networking

You have undoubtedly heard the “the whole is greater than the sum of its parts”. This phrase describes networking very well, and explains why it has become so popular. A network isn't just a bunch of computers with wires running between them. Properly implemented, a network is a system that provides its users with unique capabilities, above and beyond that the individual machines and their software applications can provide.

Most of the benefits of networking can be divided into two generic categories: connectivity and sharing. Networks allow computers, and hence their users, to be connected together. They also allow for the easy sharing of information and resources, and cooperation between the devices in other ways. Since modern business depends so much on the intelligent flow and management of information, this tells you a lot about why networking is so valuable.

Here, in no particular order, are some of the specific advantages generally associated with networking:

o  Connectivity and Communication: Networks connect computers and the users of those computers. Individuals within a building or work group can be connected into local area networks (LANs); LANs in distant locations can be interconnected into larger wide area networks (WANs). Once connected, it is possible for network users to communicate with each other using technologies such as electronic mail. This makes the transmission of business (or non-business) information easier, more efficient and less expensive than it would be without the network.

o  Data Sharing: One of the most important uses of networking is to allow the sharing of data. Before networking was common, an accounting employee who wanted to prepare a report for her manager would have to produce it on his PC, put it on a floppy disk, and then walk it over to the manager, who would transfer the data to her PC's hard disk. (This sort of “shoe-based network” was sometimes sarcastically called a “sneakernet”.)
True networking allows thousands of employees to share data much more easily and quickly than this. More so, it makes possible applications that rely on the ability of many people to access and share the same data, such as databases, group software development, and much more. Intranets and extranets can be used to distribute corporate information between sites and to business partners.

o  Hardware Sharing: Networks facilitate the sharing of hardware devices. For example, instead of giving each of 10 employees in a department an expensive color printer (or resorting to the “sneakernet” again), one printer can be placed on the network for everyone to share.

o  Internet Access: The Internet is itself an enormous network, so whenever you access the Internet, you are using a network. The significance of the Internet on modern society is hard to exaggerate, especially for those of us in technical fields.

o  Internet Access Sharing: Small computer networks allow multiple users to share a single Internet connection. Special hardware devices allow the bandwidth of the connection to be easily allocated to various individuals as they need it, and permit an organization to purchase one high-speed connection instead of many slower ones.

o  Data Security and Management: In a business environment, a network allows the administrators to much better manage the company's critical data. Instead of having this data spread over dozens or even hundreds of small computers in a haphazard fashion as their users create it, data can be centralized on shared servers. This makes it easy for everyone to find the data, makes it possible for the administrators to ensure that the data is regularly backed up, and also allows for the implementation of security measures to control who can read or change various pieces of critical information.

o  Performance Enhancement and Balancing: Under some circumstances, a network can be used to enhance the overall performance of some applications by distributing the computation tasks to various computers on the network.

o  Entertainment: Networks facilitate many types of games and entertainment. The Internet itself offers many sources of entertainment, of course. In addition, many multi-player games exist that operate over a local area network. Many home networks are set up for this reason, and gaming across wide area networks (including the Internet) has also become quite popular. Of course, if you are running a business and have easily-amused employees, you might insist that this is really a disadvantage of networking and not an advantage.