Network Architecture
There are several ways in which a network can be designed: peer-to-peer, client/server and mainframe systems. These are also referred to as different types of network architecture.
In a peer-to-peer, or P2P, network, tasks are allocated among all the computers in the network. There is no real hierarchy among the computers, and all of them are considered equal. This is also referred to as a 'distributed architecture,' or 'workgroup without hierarchy.' This is the simplest type of architecture since it does not have a central server.
In a client/server network, a number of network clients or workstations request resources or services from the network. One or more network servers manage and provide these resources or services. The clients are computers that depend on the server for data and software. In a mainframe system, all the processing is done by a single, very powerful computer. Individual terminals are used to access the mainframe computer but don't run any applications themselves.
Client/Server
Most Local Area Networks (LANs) use a client/server architecture. Network servers contain data and software applications that can be accessed by the clients in the network. Network servers are also referred to as 'computer servers,' or simply 'servers'. Sometimes, a server is described in terms of the specific service it provides, such as an e-mail server, print server or storage server. Many servers, however, provide all these services.
Servers are typically computers with more processing speed, memory and hard disk space than a regular desktop computer. Network servers run their own operating system that manages various network tasks, as well as services that run on the network. Depending on the need for network storage and services, a single network may use anywhere from only one to a large number of servers.
'Clients' are hardware devices that provide end users with access to data and services on the server. Desktop and laptop computers are examples of typical clients. You can also use these devices more or less independently. For example, you can open up software applications, create and edit documents and save files on the local storage medium, such as a hard disk. However, in a typical client/server network, a number of essential tasks are not performed by the clients alone. Some typical examples are:
- A printer is connected to the network, and to print a document, the client sends a print request to the server
- E-mail messages are stored on the server, and the client is used to view and manage messages
- Very large databases are stored on the server, and the client accesses these without copying them onto the local hard drive
There are a number of different types of clients. Stand-alone desktop and laptop computers that are used as clients are known as 'fat clients.' These computers can run programs on their own, have a local hard drive for storage and only use the network for certain tasks.
'Thin clients,' on the other hand, have their own processor but may not have a hard drive. They depend entirely on the network to access software applications and data. 'Dumb terminals' have a monitor, keyboard and a minimum amount of hardware to connect to the network. All the processing is done by the server. Good examples of thin clients are computers at a public library. Typically, they are only used to access the library's catalog, and they don't run any other applications.
Mainframe Systems
Computer networks have become part of everyday life. Take the example of a bank. Every moment of the day, customers carry out transactions - deposits, withdrawals, transfers, etc. A typical national bank can easily have over one million customers, and they can access their account information at hundreds of different branches, thousands of ATM machines and from just about any computer or smartphone. The account information for each customer needs to be kept up-to-date in real time.
Consider for a moment what kind of computer you would need to manage all this account information. You probably get the picture - this is not the kind of computer you can buy at your local electronic store. You need a mainframe.
A mainframe is a powerful computer to handle all the processing of large amounts of data. They are typically used by large companies or government agencies. The term originates from the large cabinets that were used to store the processor, memory and other parts of early computers. The term continues to be used to distinguish between very large and powerful computing systems and regular personal computers (PCs)
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