A network is a group of devices (PCs, printers, etc.) or nodes connected by communications circuits so that users can share data, programs and hardware resources. A network has two main elements: the physical structure that links the equipment and the software that allows communication.
The physical distribution of nodes and their circuits is known as network topology or architecture. The software consists of the protocols, i.e. the rules which determine the formats by which information may be exchanged between different systems. We could say that cables and transceivers (the architecture) allow computers to hear one another, while the software is the language that they use to talk to one another over the network.
As regards the cables, they consist essentially of the transceiver the hardware that sends and receives network signals. At present the most widely used transceivers are Token Ring, Ethernet and LocalTalk. Token Ring is the most common method of connecting PCs and IBM mainframes. Most Token Ring adapters transmit data at a speed of 16 megabits per second. With Ethernet, data is transmitted at 100 Mbits/sec. Ethernet provides a very robust, trouble-free architecture with good levels of performance. In this regard, Ethernet is the best solution for fast and intensive activity.
LocalTalk transceivers are the cheapest of all because they are directly included in each Macintosh. However, they are a bit slow, which is why most Macs come with built-in Ethernet.
As for protocols, these are rules which describe things like transmission speed and physical interfaces. The Token Ring protocol avoids the possibility of collisions. To transmit data, a workstation needs a token and as there is only one token per network, holding one guarantees sole use of the network. With Ethernet there are other options, of which TCP/IP (Transmission Control Protocol/Internet Protocol) is perhaps the most useful since it allows different operating systems to communicate with each other. With regard to LocalTalk networks, they use AppleTalk protocols. The Macintosh operating system includes the AppleTalk manager and a set of drivers that let programs on different Macs exchange information.
LANs can be interconnected by gateways. These devices help manage communications and control traffic on large networks. They change the data to make it compatible with the protocols of different networks.
The words to the text:
device ,
node
circuit ,
to link ,
to determine
mainframe ,
to transmit ,
robust ,
solution
interface
to avoid
collision ,
option ,
compatible ,
