Lektsiya №15

Topology of the networks

THE REFERENCE. The Topology as mathematical notion:

The Topology (from grech. topos - a place and... логия), section mathematicians, exploring topological characteristic of the figures, t. e. characteristic, not changing under any deformation, produced without breakup and splicing. The Example topological characteristic figures are dimensionality, number crooked, limiting given area and t. d. So, circumference, ellipse, sidebar of the square has one and same topological characteristic, t. k. these lines can be deformed one in other described above by image; in ditto time ring and circle possess the different topological characteristic: circle is limited by one sidebar, but ring - two.
When making the network depending on problems, which she must will execute, can be marketed one of three network topologies.
Bus topology
The Workstation by means of network adapter are connected to the general pathway (the bus or cable). The Similar image to the general pathway are connected and other network device. In process of the work to network information from sending stations enters on adapters all workstation, however, is perceived only by adapter to that workstation, which she is addressed.
Architecture of the computer networks

Polnosvyazannaya network. The Network, in which there is branch between any two nodes. The most Most important feature to computer network - her(its) architecture.

The Way of management. Depending on way of management distinguish to network:
o "client/server" - in they stand out one or several elements (their name - a servers), executing in network, controlling or special servicing functions, but rest elements (the clients) are terminal, in they work to users. The Network client/server differ on nature of the distribution function between server, in other words, on types server (for instance, file-servers, servers database). At specialization server on certain applications have a network of the portioned calculations. Such network distinguish from site systems also, built on мэйнфреймах;
o одноранговые - in them all elements equal; since in general event under client is understood object (the device or program), inquiring some facilities, but under server - an object, giving these facilities, that each element in одноранговых set can execute to functions and client, and server;
o сетецентрическая concept, in accordance with which user has only cheap equipment for referencing to removed computer, but network services the orders on performing the calculations and receptions to information. That is to say user not it is necessary to gain software for decision of the applied tasks, him it is necessary only to pay for execute an order. The Similar computers name "fine client" or network computer.
On type of the ambience of the transmission possible to select to network, built on the base of the coaxial cable, winding pair(vapour)s, оптоволокна, radio link, infrared range of the electromagnetic radiation.
On send rate of information to network split into low- (before 10 Mbit/c), fair- (before 100 Mbit/c) and speediest (over 100 Mbit/c).
Besides, sometimes select the network on degree интегрированности: integrated networks, неинтегрированные network and subnets.
The Integrated computing network (интерсеть) presents itself interconnected collection of the many computing networks, which subnet are identified in интерсети. In automated system of the major concerns to subnets include the computing facilities of the separate design subdivisions. Interseti need for association of such subnets, as well as for association of the technical facilities of the automatic systems of the designing and production in united system complex auto-матизации (CIM - Computer Integrated Manufacturing). Usually интерсети are adapted for different type communication: telephony, e-mail, transmissions видеоинформации, numerical datas etc., and in this case they are identified the networks of the integral service.
The Development интерсетей is concluded in development of the facilities of the interfacing the heterogeneous subnets and standard for building of the subnets, изначально adapted to interfacing.
Depending on that, alike or different COMPUTER use in network, distinguish the network sister COMPUTER, named uniform, and intermix COMPUTER - lumpy (гетерогенные). In large automated system, as a rule, network turn out to be lumpy.
The Network also distinguish depending on used in them protocol and on way of the switchings.
The Architecture to network - a marketed structure to network data communication, defining her(its) topology, composition device and rules of their interaction in network. Within the framework of architecture of the network are considered questions of the coding to information, her(its) addressing and transmissions, control flow messages, error and analysis checking of the functioning to network in emergencies and at deterioration of the features.