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How to mount your own local network

With every major day implantation of the computer science in our lives, there comes a moment in which we meet that that computer that we buy a few years ago has had descent, and there are two, three or more computers those who inhabit our house or office; there has come the moment to connect them in network.

In network? And why?, he will wonder. Since to make use of this proliferation of computers and devices: to use the enormous hard disk of the most modern to keep files of the ancient one without using the uncomfortable diskettes; to print in several computers with the only printer; to play the same game simultaneously several players... All this and much more it is possible to obtain thanks to a computers network.

It is necessary to bear in mind that the computers networks are an authentic science inside the computer science; a computers network can be something so complex and enormous like Internet, or a little so simply as two computers connected to a cable. Depending on what hardware and software do we use, the possibilities grow up to the infinite, but the complexity also; on these pages we will treat only of how to mount a network sencillita, for a dozen or less of computers, that it is the most common case. If what he wants is to connect a company of major size, hire a specializing technician or it will spend it badly.

Some basic concepts

Not to have to repeat them further on, we will explain them here. Read this paragraph with attention, do not try to enter the brave ones the installation process not of components buy without knowing these terms thoroughly.

Type of network

Although we might use other alternatives as Token Ring, the network that we are going to mount is of the class Ethernet. These networks are easy to mount, his yield is very good and they are very widespread, therefore the components are cheap and easy to find. The speed of a network Ethernet is quite high: 10 Mbits/s, or what is the same, 1,25 Mbytes/s; that is to say, that the content of a diskette takes not even two seconds in being transmitted. Although skylight is that the final yield will depend on the number of connected computers and on the traffic of the network, but it turns out to be a number certainly spectacular.

If our needs are even major, we can mount a network Fast Ethernet. The networks Fast Ethernet are an enlargement of the standard Ethernet that they come up to 100 Mbits/s (12,5 MB/s), what is more than sufficient for any use that occurs to us. Also, the compatibility with Ethernet is guaranteed, up to the point of which many cards of network can be used in both types of networks without need of doing no change.

As for the size, since our network will be distributed in a limited space (an office, a house, a building) it will be of the type named LAN (Local Area Network, network of local area).

Card of network

Cards of network Ethernet with bus ISA of the mark Genius

Also known like NIC (of the Englishman Network Interface Card), it is the element that we will connect to the PC to provide the network support. It usually comes in format ISA or PCI; for the standard Ethernet it proves more than enough ISA'S band, but for Fast Ethernet it is worth using PCI. The prices of these cards are low, I half-close to 5.000 pts, therefore he is worth buying them of a mark known as 3Com.

Anyway, the cards of network are much standardized, for what is not common to find problems; to many cards for classic Ethernet sometimes they are named "compatible with NE2000", a card of network of Novell that is something like standard SoundBlaster of the sound cards. Other computers (of mark) there include the network support in the motherboard, like many Dell, Compaq or IBM.

The wiring

(Con L, who is not the same as the pissed off one). If the computers networks receive this name it is for the cables. A network Ethernet can use many types of cables, although we will only treat two:

  • 10BASE-2: or RG58, or BNC or thin coaxial cable. It is one of the most classic cables; of a diameter I half-close to 0,5 cm, every stretch can have a 185 m maximum length, with approximately 30 computers distributed in this space. It is relatively easy to use and to mount, although it turns out to be something delicate and can be difficult to detect where it is broken.
  • Cable 10BASE-T4 (with 8 interior cables)
  • 10BASE-T: or UTP, or RJ45 or cable of braided pair. Externally it is just as the telephone, enclosed cable in the connectors (the pieces RJ45), although they must never make a mistake. With a maximum length of approximately 100 m for stretch, it is very comfortable of using, resistantly and easily to diagnose errors, although so called hub needs to use a device that the buy gets dearer.

To use one or other of these cables depends on several things:

  • The coaxial cable does not allow speeds of any more than 10 Mbits/s, by what it cannot be used in networks Fast Ethernet.
  • The hub is a relatively expensive element, approximately 10.000 pts for one with capacity for 8 computers; the hubs for Fast Ethernet are usually more expensive than the normal ones.
  • The cables 10BASE-T can belong to diverse qualities and guys (according to his level or category). For Ethernet 3 is enough with level cables with 4 interior cables; for Fast Ethernet cables TX can be used, with 4 interior cables but of level 5, or cables T4, of level 3, 4 ó 5 but with 8 interior cables instead of 4.

A practical rule is to use coaxial cable when we have to connect a limited number of computers, 3 ó 4 at most, and leave the cable of pair braided for cases of more computers, or many in the same room or area, or when we need the enormous speed of Fast Ethernet. Certainly, the cable for Fast Ethernet is called sometimes "100BASE-..." in allusion at the speed of 100 Mbits/s of these networks.

The hub

As we were saying, it is an element that only there uses in networks with cables telephone type (10BASE-T, TX, T4...), being unnecessary in those of coaxial cable. The hub is an element of vital importance, therefore there is not convenient to haggle in the buy of the same one, especially if we want to buy one who supports networks Fast Ethernet.

A typical hub, of the mark 3Com

Physically all the hubs are similar: small boxes of rectangular form seemed to big external modems, with numerous connectors for the cables and a series of luminous indicators that show the state of the network, what turns out to be fundamental at the time of diagnosing problems.

Most of the hubs can join some others to extend the network, although for a network of the size that we are interested in an only one is worth buying hub that governs the whole network. It is always convenient to buy a hub with a pair of ports more than we need, since this way we will save ourselves money and conflicts if we decide to extend the network in the future.

Servants and networks point to point

As for the logical part, two types of networks exist fundamentally: the networks governed by a servant and the networks point to point (peer to peer). The servant is a computer of big potency and capacity that acts of umpire and judge of the network, he handles it, controls his safety and distributes the access to the resources and the information; on the contrary, in the networks point to point no computer is over other, but a democracy species exists and the resources are distributed as the user of every computer wants.

The networks with dedicated servant are usually more complex than handling, in addition to which we must buy the servant, who is a special and quite expensive computer, both in hardware (hundreds of Mb of memory, big discs SCSI...) and in specializing software (Microsoft Windows NT for servants, Novell Netware, UNIX... or Linux, which is free but complicated to use). Nevertheless, as for safety and services there are undoubtedly the best; if it has to mount a network with more than one dozen of computers and/or the safety worries him, a computer technician hires and mount a network of this type.

The networks point to point are simpler to use, although they are more insecure and absolutely not advisable for networks of more than one or two dozens of computers. An intermediate solution for networks point to point is to have in the network of a computer with more potency that devotes itself exclusively to routine tasks like impression, safety copies or storage of files, what liberates to the rest of computers without need from having an authentic servant.

The software

A network is not anything more that four cables until we do not install a software to be able to handle it. The network software has two parts: the protocol of network, which is something like language that the cards are going to use to communicate, and the proper program of communications that translates our orders to the language of the protocol of network.

Pantallazo of Windows 95 showing departs from the support for networks incorporated

The most common protocols are the NetBEUI, the IPX/SPX, and more recently the TCP/IP (that is the one that uses the Internet network). As for the program to be used, it will depend on if our operating system includes or do not support for networks. If it includes it, we will have to form it so that he behaves like a type or other of client (for networks type Netware, networks type Microsoft...); if it does not include it, we will have to install an additional program (like Novell Personal Netware for TWO).

The design of the network

Now when it already knows enough on the networks, let's begin designing his own. In the design of a network it is where more mistakes are committed and where it turns out to be more difficult to correct them. Read again the previous explanations, take role and pencil and rise the following questions to him:

  • How many computers am I going to connect in network?
  • How many will I add in the future?
  • How are the computers ready?
  • Did a servant need?
  • What speed do I need?
  • What do I want to share and what want to support privately?
  • What software do I have?

Do not forget to do a detailed sketch of the disposition of the computers (present or future) in which there appear with the biggest precision all the measurements of importance, which will be fundamental at the time of installing the cables or deciding the situation of the hub.

If it is a question of joining two or three computers at home and the safety is not necessary, the answers it is possible that they take him to a network Ethernet point to point with coaxial cable and Windows 95 or Windows 3.x, in that share the hard disks, the CD - ROM, the unit Zip, the scanner and the printer is usually simple... and to we allow to play also in network, quite without too much effort or investment.

If it is a question of a similar case but the safety yes is an importance factor, it can think of mounting the same type of network but with Windows NT for workstations (workstations), that offers more safety options to his information, or simply to put a password in the BIOS that does impossibly to light his computer without his permission (to see how this does I pulsated here).

If he needs the speed maximum but to join only a few computers, his a network Fast Ethernet is point to point; of course, be careful at the time of acquiring the material, neither remain short nor be wrong of cables, cards not hub.

Hubs apilables for big networks, of the mark 3Com

If for what he looks is a network with easy installation and that could grow without problems, install a network based in hubs and cable of braided pair. Remember not to remain short with the hub, if 6 needs to connect ó 7 computers one consider to be bought with more than 8 ports, do not be that then it extends the network (to join hubs is perfectly possible, but: why to complicate us?).

And if it has to join many computers, he needs enough safety and the network must be rapid, very trustworthy and with complex capacities, hire a professional to mount it and to manage it. It will cost him a money in salary, servant and the others, but it will save in griefs, problems and errors of concept.

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