The main problem consists in simultaneous providing these, for example, the highest speed of data transmission is limited to the most distance of data transmission at which the demanded data security level is still provided. The easy and simplicity of expansion of cable system influence its cost.
Modern modems are executed on the basis of specialized BIS (big integrated schemes), carrying out practically all functions of the modem. It provides small dimensions, high reliability and simplicity of use of modems.
Computer networks with treelike structure are used where direct application of basic network structures in pure form is impossible. Network amplifiers or apply to connection of a large number of workstations to adaptor payments. The switchboard possessing at the same time and functions of the amplifier, the active concentrator.
In the consciousness we closely connect concept of the personal computer with a computer network. The feeling of functional inferiority accompanies us if the computer standing houses for any reasons is not connected to Internet, and it is quite indicative – who needs such apartment from which it is impossible to go outside?
The principle "you me - I" find for you broad application in systems of electronic bulletin boards. Each registered user receives the daily period of time which is strictly limited to the System Operator for realization of the intentions and desires. It sometimes happens insufficiently even to accept the List available on given BBS files (Filelist). The user has to purposefully seek to be pleasant to the Sysop, to transfer it the most interesting and rare ON which can interest, notify it on the latest news, gossips, and also as often as possible to treat with beer. The last action most significantly influences a raising of Level of Access (Access Level) of the user to this BBS.
In a standard situation for the tire Ethernet network the thin cable or Cheapernet-kabel with a troynikovy connector often use. and especially connection to such network demand a rupture of the tire that violation of the circulating flow of information and lag of a.
What is the LAN? Understand joint connection of several separate computer workplaces (workstations) to an data link as a LAN. Thanks to computer networks we possibility of a simultaneous of programs and databases several users.
- work in the off-line mode when it is not required continuous presence on post knot of Sisor. It is only enough to specify to the special program mailer (Mailer) time of system events and the address where it is necessary to take away mail, all the rest will occur automatically!
Large network servers similar Elvis, Izhma, Kiae, Simte, Chci and dr belong to professional BBS. in the Relcom networks, and also small kommerchesko-reklamny stations. Their main differences - providing access for a monthly fee, the 24-hour schedule of work, a wide choice offered ON, the professional paid Sysop, etc.
The main problem at ring topology is that each workstation has to participate actively in transfer of an, and in case of failure at least all network will be paralyzed by one of them.
On a row with known topology of computer networks the ring, a star and the tire, is put and combined into practice, on an example the structure is treelike. It is formed generally in the form of combinations of topology of computer networks. The basis of a tree of a network settles down in a point (root) in which lines of information (a branch gather.
At tire topology the environment of information transfer is represented in the form of a communication way, available day of all workstations to which all of them have to be connected. All workstations can come into contact with any workstation which is available in a network.
Cheaper, than the Ethernet-cable is connection a Cheaperyonet-cable or as it is called often, thin (thin) Ethernet. It is also 50-omny coaxial cable with a speed of information transfers of ten million bps.
Recently modems become an integral part of the computer. Having installed the modem on the computer, you actually open for yourself the new world. Your computer turns from the isolated computer into a link of a global network.