Defining a local area network
Saturday 03 December 2011 at 06:56 am.
The most general definition of a local area network (Local Area Network, LAN) is a communications network used by a single organization through a limited distance, which allows users share information and resources such as hard disk space, printers, CD-ROM, etc.
elements of a network
A computer network consists of both hardware and software. The hardware includes: workstations, servers, network interface card, cables and connectivity equipment. The software is operating system (Network Operating System, NOS). Each computer workstation connected to the network retains the ability to function independently, making their own processes. Also, computers become networked workstations with access to information and resources contained in the file server itself. A workstation does not share their resources with other computers. This can be anything from a PC XT to a Pentium, equipped according to user needs, or other architecture also different as Macintosh, Silicon Graphics, Sun, etc.. Servers are computers able to share those resources with others. Shared resources can include printers, disk drives, CD-ROM, hard disk directories, and even individual files. Server types obtained depending on the resource name they share.
Some of them are jukebox server, file server, distributed file server, file servers, dedicated and not dedicated, server, terminal server, printer, CD server, web server and mail server.Network Interface Card to communicate with the rest of the network, each computer must have one network interface card (Network Interface Card, NIC). They are also called network adapters or network cards only. In most cases, the card fits into the expansion slot of the computer, although some are external units that connect to it via a serial or parallel port. Internal cards are almost always used for PC's, PS / 2 workstations as SUN's.Interface cards can also be used on minicomputers and mainframes. Often used for external boxes for some Mac's and laptops. The interface card obtains information from the PC, makes the appropriate format and sends it through the cable interface card to another local network. This card receives the information, translates it so the PC can understand and sends it to the PC. There are eight functions of the NIC host Communications Training Packet Buffering card serial to parallel conversion and decoding Coding Access Cable Transmission and Reception Greeting These steps make data from the memory of a computer's memory to pass another.
Cabling the LAN must have a system of wiring that connects individual workstations to file servers and other peripherals.If there is only one type of cabling is available, the decision would be simple. The truth is that there are many types of cables, each with its own advocates and as there is great variety in terms of cost and capacity, the selection should not be a trivial matter.
Twisted Pair Cable: It's by far the least expensive type and most common network medium.
Coaxial Cable: It's so easy to install and maintain as twisted pair, and is the preferred medium for large LAN.
Fiber Optic Cable: It has higher throughput than previous ones, is immune to radio frequency interference and capable of sending signals over considerable distances without losing its strength. It has a higher cost. Connectivity equipment usually for small networks, the cable length is not limiting for their performance, but if the network grows, you may ever need a further extension of the cable length or exceed the specified number of nodes. There are several devices that extend the length of the network, where each has a specific purpose. However, many devices incorporate the characteristics of another type of device to increase the flexibility and value.
Hubs or concentrators: They are a central connection point for network nodes that are arranged according to a star physical topology.
Repeaters: A repeater is a device that can extend the length of the network, amplifies and retransmits the signal network.
Bridges: A bridge is a device that connects two separate LAN to create what appears to be a single LAN.
Routers: Routers are similar to bridges, only operating at a different level. Generally requires that each network has the same network operating system, to connect networks based on completely different logical topologies such as Ethernet and Token Ring.
Gates: A gate allows network nodes to communicate with different types of network or other devices. Podr'a be, for example, a LAN consisting of IBM compatible computers and a Macintosh. Network Operating System After completing all required hardware to install a LAN, you need to install a network operating system (Network Operating System NOS), which manage and coordinate all operations of this network.
