A brief introduction to network infrastructure, the history and modern applications
A net may be used to signify a pattern, such as the criss-crossing pattern of the net a fisherman uses to scoop up fish, or the wires that you see running between telephone poles. Work implies that some energy has been used or is used to establish the pattern. Infra means under or below, and structure is something composed of interrelated parts. The infrastructure of a network, then, is the underlying interrelated parts that form a constructed net pattern.
People network. Telephones network. Computers network. In each instance, we mean these communicate, that is, send and receive data or messages in a specified way over some medium that is able to carry the data or messages reliably from sender to receiver. If the communication is one way only, from sender to receiver, we call this communication type simplex. If the communication is two way, with both parties of the communication being able to send and receive messages, we call it duplex communication. Whether simplex or duplex, the hardware, software, protocols and methods people, telephones, computers, or other classes use to communicate messages between each other is the communication's network infrastructure.
Electronic communications originated with the invention of the telephone. In the case of telephones, two telephones are linked through telephone wires. The link is initially virtual, not direct. The telephone number used to make the call is used by a series of switches, between segments of wire, to create a route for the two telephones to communicate over. The telephone itself has a microphone, that converts the sound waves made when you speak, into electronic pulses that travel over a wire. The telephone also has a speaker that receives electronic pulses and converts these back to sound waves. Two telephones, wires and switches, as well as telephone poles, connectors, and other parts constitute the telephone system's network infrastructure.
Hardware refers to something material and designed to perform a function. Hardware requirements are only part of what we need for a telephone system. The telephone systems use a protocol for making a connection. First, the receiving telephone must ring before a connection can be established. Then, the person receiving the call must answer the call by picking up the telephone receiver, or perform some other action to signal the system that the person at the other end has answered. Software is not required for a telephone network. The switches the system uses does some decision making, but this logic is hardwired. The telephone system uses other methods and procedures to monitor the network lines. All of these, the wires, switches, protocols and monitoring sub-systems constitute the telephone system's network infrastructure.
Just as people may communicate over the telephone network infrastructure, computers may also communicate with each other over the telephone network. The telephone network infrastructure is not the only type of network infrastructure computers use to communicate. Local area networks, (LANs), connect computers to each other within a specific locale, such as an office building, with cables that may be attached from one machine to another, or attached to a switch or router that determines which attached computer, or peripheral, such as a printer or fax, is supposed to receive the message. The messages computers send to each other are sent in packets. Commonly accepted standards specify how a message is to be packed. The header of a packet normally contains the address of the computer to which the message is directed. LANs may also be connected to each other with switches or routers, or by high-speed backbone cables. Each LAN of a network of LANs is a sub-net.
A LAN may also feed into a switch or router that is connected to the telephone network infrastructure. Messages may be passed from one LAN over the telephone system to another LAN. This is also called a wide area network (WAN). An intermediate network between a WAN and a LAN is called a Metropolitan Area Network. Typically, cables, infrared communication devices or radio transmitting and receiving devices connect a small community, such as a group of office building.
The cabling, connectors, switches, hubs, nodes and other physical devices are part of the network infrastructure, as are the protocols used for messaging, connecting, securing and monitoring the network. The network infrastructure includes the manner in which the computers and devices are connected, the resource sharing models employed (sneaker, peer to peer, client/server), the topology used (bus, ring, star, mesh), the networks used (public, private) and even the support and administrative personnel. All these and others not mentioned, comprise the network infrastructure, the structure that enables computers and their peripherals to communicate.