Networking
From TPU Reference
erdronr A network consists of more than one computer or device connected together in some manner. This series of 'networked' electronics consists of terminals and nodes.
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Terminals
Terminals are the devices that are responsible for sending data to and recieving data from other computer systems on the same network. The category of terminals can further be narrowed down into 'Dumb Terminals' and 'Intelligent/Smart Terminals'.
Dumb Terminals - A computer or device located in a network that does not possess processing capabilities, rather it relies on the processing capabilities of another computer or server on the network. As a result, they tend to have limited functionality. These terminals mostly are hugely reliant on the network in order to be of use to the participants that utilize them.
Examples of Dumb Terminals include Automated Teller Machines (ATM's) and Workstations that are connected to a mainframe or central computer for enhanced processing and storage capabilities.
Intelligent Terminals (Smart Terminals) - A computer or device located on a network that is capable of performing its own processing, storage and a variety of input and output tasks. Intelligent terminals are usually known to mainstream society as Personal Computers or Workstations.
Examples of Intelligent Terminals include your everyday home computer, laptops, servers, personal digital assistants and so on.
Nodes
In simplest terms, a node is basically a broad description for any device connected to a network. Each node of the network has a specific location, being assigned some sort of reference address so that terminals and other nodes can communicate with or through it. Nodes can include printers, storage devices, PDA's, cell phones, routers, switches hubs and even terminals.
Network Classification
Networks can be classified into two different categories, Local Area Networks and Wide Area Networks.
Local Area Networks - Consist of a collection of connected computers and their associated peripherals within a specific geographically defined location. This location varies depending on the use of a network.
In a home network, the Local Area Network may be confined to several rooms or a simple connection between two floors. A business or government institution on the other hand may involve the use of a Local Area Network that spans the whole building or several buildings across a single block of land. Nevertheless LAN's are generally small in terms of definition.
Advantages
There are many advantages of utilizing a Local Area Network, these include:
⢠The sharing of resources across a network. Such as printers, storage devices and internet access.
⢠Enhancing work efficiency by running the same programs or applications across the network for more than one person to use.
⢠Improved communication between users in terms of socialization and data transmission.
⢠The ability to play Counter Strike and PWN your friends!
⢠Speedier and easy way of transferring files when the Local Area Network already exists.
⢠Generally more secure and safe than the internet, which is a Wide Area Network (WAN).
⢠Higher data transmission rates than wide area networks.
⢠Does NOT require regular fees for the lease of lines from Internet Service Providers.
Disadvantages
Local Area Networks also possess several disabilities:
⢠Local Area Networks may not be cost effective across larger spans.
⢠Privacy may be invaded by others when adequate security is not employed to prevent people accessing your file storage.
⢠Drilling and other wall destructive activities may need to occur in order to run cables.
⢠Technical knowledge is required to set up and maintain networks and their devices.
Wide Area Networks - Consist of computers and devices that are connected over a much broader area than a LAN. The most well known Wide Area Network is the internet, which connects millions of computers and their users world wide.
Wide Area Networks usually involve the use of a host computer, which generally would require extensive processing power and huge storage facilities. This computer would normally be a mainframe or some other type of server connected to a large number of terminals tasked with co ordinating the vast number of computers connected to the network and in turn either redirecting those computers to specific servers in order to provide file access or in the case of smaller WAN's dealing with the computer in the network directly.
These Wide Area Networks generally utilize a private leased line in order to transmit data across the network. In earlier years, simple copper phone lines were the norm for such data transmission, but they have quickly become redundant with the availability of hugely popular digital subscriber lines as well as the utilization of fibre optic cables, permitting greater data transmission speeds with less electronic interference as well as proving to be increasingly more reliable, especially in the number of users that can access the line at any one time.
Packet Switching - In a Wide Area Network, this is required in order to allow multiple users to peruse the same transmission medium at one time by dividing data into small groups called Data Packets, which are transmitted and reconstructed at the other end of the line. Even if this data arrives in the wrong order, control instructions tell the computer how the data has to be rearranged.
Network Topologies
Network topologies encompass the physical organisation of devices and computers in a network. The three most popular are:
Bus Network - An arrangement of devices connected to a single 'bus' or transmission medium. Each device on the bus has a specific address and can only recieve transmissions that were intended for it to recieve. Each device or computer checks the bus for data refered to its address and retrieves it. This network is the easiest to set up, and is generally found in the home.
An example of this would be three computers connected together via a router with a printer attached to the router also. If one computer fails in the network, the network is still operational. However if the router fails, the whole system goes down.
Ring Network - Arrangement of computers and devices where all devices are connected to one another, with data travelling around to each device until it gets to its specified address. As data travels past, each node of the network can add extra packets of its own to send to the other devices of the network.
An example of a ring network would be five computers connected in five adjacent rooms connected by hubs. It is simple to see that although there is less mess involving cable that the downside of this network is that if one device fails the whole network crashes.
Star Network - This arrangement involves a central computer with each device individually connected to it. The central computer would utilise a switch in order to be able to connect to so many devices. The central computer here makes it possible to use either Dumb or Intelligent terminals, with the central computer doing the processing in the case of the surrounding computers being Dumb terminals. The central computer is generally a mainframe, and if it fails to operate, the network becomes non-functional.
