LAN enterprise example. Coursework: Organization of a local computing network in the enterprise. The campus subsystem of this network is a combination of several buildings with each other with the cable sewage of the external fiber-op

General concepts

Do not talk about the role and importance of competently organized, flawlessly working local computing network Enterprises. Often it is livised by the guarantor of a successful business. And vice versa with a bad organization, insufficient attention to the issues of its construction and renewal, collapse comes in the organization of labor in the enterprise. If you rephrase a well-known saying, then you can say: "LAN- like air, it is not noticed when it is, and suffocating when it is not."

Everywhere we face various versions of local computing networks. Often out of the houses LAN, growing up to the scale of the area or a whole city, the computing network becomes urban (MAN).

The local computing network must have a number of properties:

Scalability - At the initial stage, the Organization may invest a minimum of funds for laying local networks that would meet its current goals and tasks. In the future, if necessary, it will always be able to easily expand the networks and connect additional equipment.

Flexibility - For timely response to changing technology requirements, it is necessary to have its flexibility to an existing local network. In other words, the network must be adapted for most types of network cables: twisted pairs, coaxial, as well as fiber optic, and it is desirable to support technologies, starting OtherNet, FasteThernet, to GigabitetherNet above.

fault tolerance - The system of local networks mandatory includes backup lines in case the main causes of the reasons fail. For example, you can connect the server (server farm) to several switches / routers having spare paths - with one concentrator / router failure, you can always quickly go to another in automatic mode, without interrupting the communication session.

Reliability - Long-term use of a local network in accordance with the increasing need for it implies the need to search for optimal options to increase its reliability, as forced downtime costs to organize too expensive when there is a valuable every minute. Therefore, it is impossible to neglect existing software and hardware and tools that allow to increase the reliability of local networks.

Protection - An important property is the security of networks from an unauthorized invasion, as well as internal user actions. It is solved with the help of a set of measures, including software hardware, a hub, switch, router, firewall, a remote access server, as well as administrative measures, which generally makes it possible to fully control the current processes and ensures the safety of the most important data of the organization.

Controllability - The local network must have powerful tools for its monitoring, to quickly detect interference and faults, to eliminate the possible downtime mentioned above. There are many products designed for the operational collection of technical information about the network status and its parameters - an example can serve as NMP, RMON. In addition, it is possible to control the network via a web interface that can be used almost anywhere for remote access.

In the simplest case, the local computing network consists of two computers equipped with a network card connected to an adjustable cable (coaxial or twisted para). It should be remembered that there is a non-standard patch cord in such a scheme, and the so-called crossover. And of course you need to not forget that the distance is interfrodent to be no more than 100 m.

The solution when the LANSTOTIC of the two-panel can be implemented and on wireless technology, in this case both computers are equipped with wireless network cards (adapters) and are connected in Point-to-point mode.

Network fee Also known as a network card, a network adapter, an Ethernet adapter, NIC (English.NetworkInterface Controller) -Periferial device that allows the computer to interact with other network devices.

SNMP (eng. Simplenetworkmanagement Protocol - Protocol simple control Networks) is a communication network management protocol based on architectureTCP / IP.

RMON-protocol for monitoring computer networks The extension of the SNMP, which is based on the SNMP basis, is the collection and analysis of information on the nature of the information transmitted over the network. Like the CSNMP, the collection of information is carried out by hardware and software agents, the data from which is received by the computer where the network management application has been installed. The distinction of its predecessor consists, first of all, in the nature of the information collected-if the information is characterized by only events that occur on the device where the agent is installed, then that the data obtained has characterized traffic between network devices.

The above-mentioned method of organizing the network of the computer is simple, and does not require special costs, such an implementation of the LAN, meets more and less. However, today's realities are such that there are tens and hundreds of computers and network devices in their composition (switches, gateways, print servers, servers, network devices storage of information, etc.), moreover, practically impressive way out global Network Internet.

The organization of the local network (still donoyakes of the local network) is mandatory begins with the definition of key points. Here is some of them:

· Determining the number of stations (ports, hosts) of the future network;

· Operational data warehouse planning;

· Alleged software;

· Estimated services (IP telephony, video observation, etc.);

· Restability of a single information space for the company's structural divisions;

· The probability of using a local network to build a unified corporate information platform (intranet).

There are several options for organizing a local network. As a data transmission environment, a twisted UTP / STP cable can be used (usually category 5E and above) or fiber optic cable. An organization of local networks is possible with wireless technology. In this case, building and configuring the local network will vary greatly depending on the technology used - wireless and wired.

Building a local network will be largely due to its size and method of placing computers. Among other factors affecting the organization and configuration of the local network, it is worth noting the presence of servers, the number of jobs, as well as the number of buildings in which the LAN is functioning.

At the stage of creating a local network and setting up a local network, it is important to have a clear idea of \u200b\u200bthe network architecture (topology). The network topology depends on the location of the PCI of their functional purpose. The choice of topology in the process of creating a local network and setting up the local network is individually - under the specific object of its own architecture.

To carry out the local network, network equipment required for each option is selected, and preferably from one reliable manufacturer.

D-Link offers the entire spectrum of active network equipment for building (upgrading) local computing networks, any level of complexity. In addition, it is important that the fact of the presence of widely extensive service maintenance of the D-Link equipment is important.

After all key points related to the organization of the future network are embarking on the creation of a cable system (in case wired solution LAN).

Intranet (English. INTRANET is also used to intranet ) - Unlike networkinet, it is internal private network Organizations. As a rule, an intranet is an internetune of miniature, which is built on using the exchange protocol and sharing some part of the information within this organization. These can be lists of employees, lists of partner phones and customers. Most often, under this term, only the visible part of the organization is only visible to the internal website. Analyznaya on the Basic HTTP and HTTPS protocols and the client-server principle, an intranet site is available from any computer. Thus, intranet is like a "private" Internet, limited by the virtual space of a separate organization. Intranet allows the use of public communication channels included in the Internet, (VPN), but it provides protection for transmitted data and measures to curb the penetration from outside to corporate nodes.

Structured Cable System (SCS)

Cable system - This is a system, the elements of which are cables and components that are associated with a cable. All applies to cable components passive switching equipment serving for connecting or physical termination of the cable - telecommunication sockets at workplaces, cross and Switching Panels (jargon patch panels ) In telecommunication rooms, couplings and splines.

Recently, when organizing a LAN, in relation to the cable system, the term is most often used. structuralCable system (SCS).

Structured Cable System (SCS) - The basis of the information infrastructure of the enterprise, which allows you to reduce multiple information services for various purposes: local computing and telephone networks, security systems, video surveillance, etc.

SCS it is a hierarchical cable system of a building or group of buildings, divided into structural subsystems. It consists of a set of copper and optical cables, cross-panels, connecting cords, cable connectors, modular sockets, information sockets and auxiliary equipment. All listed items are integrated into unified system and are operated according to certain rules.

Term "Structured" means a robust side, the ability of the system to maintain various telecommunication applications (voice, data and video transmission), on the other hand, the possibility of using various components and products of various manufacturers, and strings - the ability to implement the so-called multimedia environment in which several types of transmitted media are used - Coaxial cable, UTP, STP and optical fiber. The structure of the cable system determines the infrastructure of information technologies (from English, Information Technology), it is she who dictates the content of a specific cable system project in accordance with the requirements of the end user, regardless of active equipment that can be applied subsequently.

Typical installation works SCVNCC:

· Installation of cable channels (boxes, trays, corrugation, pipes, etc.);

· Punching holes in the walls;

· Cable gasket in cable channels;

· Setting out rosettes and seal the cable modules of sockets;

· Assembly and installation of the mounting cabinet;

· Installation and packing of patch panels and organizers.

Stages of mounting SCS:

· Studying an object for mounting SCS;

· Technical project development;

· Selection of the necessary equipment and installation at the facility;

· Testing and certification, delivery of work to the customer;

· After installation support and training

Components SCS

When creating emphasize. Cables ,connectors ,sockets and patch cords used in computing networks. In brief remark:

Copper unshielded UTP cable (eng. Unshieded twisted pair) depending on the electrical and mechanical characteristics, 5 categories are divided into 5 categories (Category 1 - Category5).

Shielded twisted pair of STP (eng. S hieldedtwisted pair) well protects the transmitted signals from external interference, as well as less radiates electromagnetic oscillations internally, which protects, in turn, network users from harmful radiation health. Special place occupied cables categories 6 and 7, which industry began to produce relatively recently. For a Category 6 cable, the characteristics are determined to a frequency of 200 MHz, and for Cable Cables 7 to 600 MHz. Category 7 cables are necessarily shielded, both each pair and the entire cable in the whole. Kabelcategory 6 can be both shielded and unshielded. The main purpose of these cables is support for high-speed protocols on cable segments of a larger length than the UTP Category 5 cable.

8p8c (8 Position 8 Contact) , often erroneously called RJ45 or RJ-45 - The unified connector used in telecommunications has 8 contacts and a latch.

InformantsAs a rule, universal, they serve as a point in the cable system for all office equipment, including not only the computer and other peripheral devices, but also the phone (i.e., it is possible to connect the cord with the RJ-11 (12).

Switching panel (cross-panel, patch panel) - One of the components of the structured cable system (SCS). It is a panel with a plurality of connecting connectors located on the front side of the panel. On the back of the panel there are contacts intended for fixed connections with cables, and connected with electrically connections. Switching panel refers to passive network equipment. Switching panels can be fixed or dialing. If in the first case, all connectors are performed by the same type, then in another case you can implement a hybrid switching panel containing connectors different types, including copper type RJ45 of different categories, fiber-optic connectors of various types, coaxial (for example, type BNC) and others. Types of installed sneakers depend on the type of task solved. The most common type of this type of devices, in modern technologies, is a 24-port fixed switching panel with not shielded connectors of the RJ45 category 5E or 6. From the back of the panel there are so-called IDC connectors (eng. Insulator Displacement Connector, connectivity insulation ).

Picture 78 . Elements SCS

There are two typical ways to use switched panels.

In the first case, the switching panel is used as a switching point between the ports of active network equipment (ASO) and workplaces ports, through the cable of the Horizontal SCS subsystem. Switching is carried out by switching cords from the panel to the ASO ports.

In the second case, the so-called double port representation, the switching panels are used in pairs, one of the panels represents the ASO ports, and the second is the ports of jobs. Switching is carried out by switching cords between panels.

Together with the switching panel it is advisable to use cable organizers To streamline suitable and existing cables.

Switching panels may differ:

but). According to the composition of the connectors

b). By the number of ports

in). By shielding

d). By way of fastening

e). By way of representing ports

Figure 79. Cross-Panel Mounting Example

Switching cord, switching cable or patch cord (from English Patching CORD - connecting cord) - One of the components of the structured cable system. It is an electrical cable to connect one electrical device to another. There may be any types and sizes, on one or both ends of the cable, the connectors connected devices are necessarily present.

The main difference switching cord from cable internal strip - Using a stranded wire, instead of solid. This reduces the transfer characteristics of the cable, but increases flexibility and reduces the minimum radius of the safe cord bending.

Switching cord used in the ambassador pigtail and it is a segment of the cable, terminated on one side by a connector of a certain type. The compound of optical pigtail with a fiber cable is carried out using welding or mechanical deline connections.

Organization SCS

In general, the entire design can be represented in this way: on one of the floors of the building containing workplace With office equipment, along the walls from connected devices and from auxiliary technical means (fire alarm sensors, IDR video surveillance systems.) Horizontal cable wiring is carried out. They converge into a single switting floor assembly (in the same way passing and on the other floors connected to the SCS). From it there is a vertical cable wiring connecting sequentially all the floors. Then the entire cable system is integrated into a common switching center, which can be placed in a special technical room.

All components are plugged with each other and are located in such a way that you can build up the entire system and expand its coverage not only within the multi-storey buildings, structures, but also between real-life objects at a certain distance from each other.

The cable system of the enterprise can be performed in various ways: according to the technology of hidden wiring, in the overhead channels, in space under the raised floor or over the mounted ceiling, etc.

Often, in terms of enterprises, saved on cables, with which the computer is connected to the cable network socket. It should be noted that these patch cords are often the reason for reducing the data transfer rate. They are subjected to the greatest mechanical exposure, while they are made by an unsuitable qualifications. Over time, their parameters deteriorate, which leads to data transfer errors, the appearance of which is quite difficult to notice.

Please note that, according to one of the manufacturers of patch cords, two thirds are not tested. It is difficult to expect the stability of the characteristics of products made in handicrafts, so it is necessary to equip jobs only by professionally performed patch cords.

Each user's working place must be equipped with a power outlet with grounding and information sockets. In small organizations, outlets of existing wiring are usually used. It should be borne in mind that the distance between the power and information sockets of one workplace according to the standard should not exceed 1 m. In addition, if necessary, the intersection of the power cable is necessary, it is necessary to perform at right angles. Often to minimize the effect of the power cable, special cables with shielding are used.

One of the powerful sources of electric interference is luminescent lamps. When laying informational cables, they often do not pay attention to their proximity to such lamps, for example, when installing new tracks over a false ceiling. To reduce the influence of this source, no interference should not be allowed to lay the information cable closer than 15 cm from the fluorescent lamp.

When placing a large number of users in a room that is not equipped with a sufficient amount of power outlets, power and information cables are frequently carried out to the workplace in one channel. According to the standard, if both cables are laid in a common channel, a solid partition should be provided between the power and information compartments.

Modern equipment connected to computer networks often consumes quite a bit of energy. Considering that only two pairs of conductors of twisted pair of four available are used in the data transfer data standards 10/100 Mbps. It is often possible to significantly save on the cable laying if you apply the equipment of the equipment by Ethernet cable. (Power Over Ethernet, PoE).

There are several options to ensure Roe.

The first is to use special switches or already having a function, or supporting it (switches allow the installation of an additional power supply, after which the provision of services is provided). This method is used in the presence of a significant number of ports with a function function, for example, when operating in the organization of IP phones. As an example, the 8-port desktop switch DES-1008PD-LINK with 4 ports.

Figure 80. DES-1008P.

The second method of supplying power through the networkEthernet is in the acquisition of special power supplies included in the "gap" of a network cable (a brown pair of conductors is used to supply the voltage of 48 V. This solution is justified when connecting single devices.

Figure 81. DWL-P200.

DWL-P200 transmits data, and electrical signals to the Ethernet device of one cable.

Special technology is applied in the commutators to check the port. Before serving, special testing is performed on the port, the parameters of the connected equipment are measured and, if it meets the requirements of the Roeing technology, the switch includes power. In the way, in port ports you can safely include conventional devices. When using "mortise" power supplies, especially their cheapest options, you should exclude the possibility of accidentally connecting other equipment.

In accordance with the IEEE 802.3Af Maximum power standard, which can be obtained by the device with a pie port, is 12.95W (with the port must provide power up to 15.4W). Connected devices often consume smaller power, for example, a typical wireless access point consumes About 11W, IP phones - from 2 to 14VTVs depending on the model. In order to save on some models of switches, the total permissible power supply in port router15.4x<количество портов>W In case of exceeding the permissible value of the power consumption, the switch starts to turn off the power of individual ports, given the priorities of the port ports, which the administrator must be assigned manually in accordance with the purpose of the connected equipment.

Fire safety requirements

The basic requirements of fire safety when laying cables in the office are as follows:

cables, Channels, Sockets, etc. must comply with a certain category of fire resistance; This is usually performed using modern ELEMENTS SCS;

power and informational cables when laying in one channel must be separated by a solid partition. The mimic distance from the power cables to information is determined by special standards, depending on the load, but usually should not be less than 12-15 cm;

holes made for laying cables between the rooms should be closed easily removable non-combustible material, for example, cement or low strength plaster, mineral wool, etc.;

when laying cables in space over mounted ceiling, it is unacceptable to use combustible materials.

The advantages of SCS

The first is the universality of SCS, which is that these systems can successfully be used to build computer networks, telephone lines, security, fire systems, as well as for video surveillance and "wiretaps" of a number of rooms.

The second - as already touched above, is easily expanding, which is of great importance in the rapid scientific and technological breakthrough forward. Thanks to this opportunity, there is a problem in the global restructuring of the established Ranesexve for 25 years when connecting new, more advanced devices.

The third is the reliability of the entire design, provided that all components are made in the same manufacturer that the root eliminates possible interference, and failures in the well-established work of connected equipment.

This technology gradually displaces the traditional cable system, and in the near future we will be able to observe a complete transition of enterprises and organizations of various levels on modern SCS.

Need to diagnose SCS

It is clear that any organization is interested in the uninterrupted work of its employees in the enterprise. And it is clear that simple work on the fault of poor-quality installation, as well as untested for compliance with international standards of structured cable systems, turns around much more losses of both temporary and financial nature, rather than their diagnostics. It is very annoying to know that the inability to work with information in the office is connected only with a small cable break or with a defect of some connector.

And in order not to be in an unpleasant situation, you need to diagnose the SCSN physical level. Another reason for the need to study the physical parameters of the network is the impact of these parameters on the test results of higher levels.

Now there are enough instruments in the market for solving such tasks. We will look at two types of devices: cable testers and SCS analyzers.

Cable testers

These devices are the simplest and relatively inexpensive. They are often used to install cables and assess the quality of the built SCS lines. Externally, there are small boxed devices, with the possibilities to identify cliffs, short circuits lived in a pair and between the cores of different pairs, the erroneous polarity of the pair, when the cores are accidentally confusing and with neighboring sites.

In some models of testers, there is a possibility of setting the wiring, as well as establishing the correspondence between the sockets of the switching panel and jobs, in the latter case, all sockets connected to horizontal line Wiring with numbered plugs. When the tester is connected to one side of the cable, its indicator highlights the plug number. Other testers can send a tone on the cable dwelling for its identification and trace.

SCS analyzers

Unlike the aforementioned cable testers, these instruments have a wider range of functions and are designed to determine not only the simplest defects caused by the absence of contact in the cable.

The analyzers are asked to identify more complex malfunctions resulting from incorrect installation when the rules of cable connections in a line (excessive cable stretching, a small bend radius, etc.). From poor-quality installation suffers from productivity worsen their electrical characteristics.

Using these devices in diagnostics, it is possible to determine the integrity of the chain, a characteristic impedance, power and transient attenuation, a signal propagation delay, line length, DC line resistance, line capacity, and electrical symmetry and noise. Such ample diagnostic capabilities determine the high cost of these devices, so they can be purchased away from anyone who deals with the installation and diagnosis of SCS.

Moscow State Mining University

Department Automated systems Office

Course project

under the discipline "Network of computer and telecommunications"

on the topic: "Designing a local computing network"

Performed:

Art. c. AC-1-06

Yurieva Y.G.

Checked:

prof., d. t. n. Shek V.M.

Moscow 2009.

Introduction

1 Design Task

2 Description of the locally computing network

3 Topology Network

4 LAN Scheme

5 OSI reference model

6 Rationale for selecting a local network deployment technology

7 Network Protocols

8 Hardware and Software

9 Calculation of network characteristics

Bibliography

The local computing network (LAN) is a communication system that combines computers and peripheral equipment in a limited territory, usually no more than several buildings or one enterprise. Currently, LAN has become an integral attribute in any computing systems with more than 1 computer.

The main advantages provided by the local network are the possibility of working together and quickly exchanging data, centralized data storage, shared access to shared resources, such as printers, Internet network and others.

Another major function of the local network is the creation of fault-tolerant systems that continue functioning (albeit not in full) at the failure of some elements included in them. In LAN, fault tolerance is ensured by redundancy, duplication; as well as the flexibility of the work of individual parts of the network (computers).

The ultimate goal of creating a local network in an enterprise or to an organization is to improve the efficiency of the computational system as a whole.

The construction of a reliable LAN, which meets the performance requirements and has the lowest cost, is required to begin with the preparation of the plan. In terms of the network is divided into segments, a suitable topology and hardware is selected.

Topology "Tire" is often called a "linear bus" (Linear Bus). This topology refers to the most simple and widespread topologies. It uses one cable, referred to as the main or segment, along which all network computers are connected.

On the network with the Tire topology (Fig.1.) Computers address the data to a specific computer by passing them through the cable in the form of electrical signals.

Fig.1. Topology "Tire"

Data in the form of electrical signals is transmitted to all computers network; However, only the address of which corresponds to the address of the recipient encrypted in these signals is received. And at each time only one computer can transmit.

Since data data is transmitted only by one computer, its performance depends on the number of computers connected to the bus. What are them more, i.e. than more computerswaiting for data transfer, the slower the network.

However, it is impossible to withdraw a direct dependence between network bandwidth and the number of computers. Since in addition to the number of computers, many factors affect the speed of the network, including:

· characteristics hardware computers online;

· The frequency with which computers transmit data;

· Type of working network applications;

· Type of network cable;

· Distance between computers on the network.

Tire - passive topology. This means that computers only "listen" data transmitted over the network, but do not move them from the sender to the recipient. Therefore, if one of the computers fails, it will not affect the work of the rest. In active topologies, computers regenerate signals and transmit them over the network.

Reflection of the signal

Data, or electrical signals extended throughout the network - from one end of the cable to another. If you do not take any special actions, the signal, reaching the end of the cable, will reflect and will not allow other computers to transmit. Therefore, after the data is reached by the addressee, the electrical signals must be repayed.

Terminator

To prevent the reflection of electrical signals, terminators (Terminators) absorb these signals are installed at each end of the cable. All ends of the network cable must be connected to anything, for example, to a computer or barrel connotor - to increase the cable length. To any free - nonconnected - the end of the cable must be connected to the terminator to prevent the electrical signals.

The local computing network is a concept that is familiar to many not at all. Almost every enterprise uses this technology, so it can be argued that each person somehow came across it. Local networks significantly accelerated production processes, thereby giving a sharp leap to their further use throughout the globe. All this allows you to predict the further growth and development of a similar data transfer system, up to the introduction of the LAN at each, even the most small enterprise.

Concept of local network

The local computing network represents a number of computers interconnected by special equipment, allowing to carry out a full exchange of information between them. An important feature of this type of data transfer is a relatively small area of \u200b\u200bplacement of communication nodes, that is, the computing machines themselves.

Local networks not only significantly facilitate interaction between users, but also perform some other functions:

Simplify work with documentation. Employees can edit and view files at their workplace. At the same time, the need for collective meetings and meetings disappears, which saves precious time.
Allow work on documents together with colleagues when everyone is behind its computer.
Enable access to applications installed on the server, which saves free space on the installed hard disk.
Save space on the hard disk, allowing you to save documents on the main computer.

Types of networks

The local computing network can be represented by two models: peer-to-peer network and hierarchical. They differ in ways to interact communication nodes.

A peer-to-peer network is based on equality of all machines, and the data is distributed between each of them. In fact, the user of one computer can access the resources and information of the other. The efficiency of the peer-to-peer model is directly dependent on the number of work nodes, and its level of safety is unsatisfactory, which is associated with a rather complicated management process makes such networks are not too reliable and convenient.

The hierarchical model includes one (or more) the main server where all data is stored and processed, and several client nodes. This type of networks are used much more often than the first, having an advantage in speed, reliability and safety. However, the speed of operation is such a LAN largely depends on the server, which under certain conditions can be considered a disadvantage.

Drawing up technical requirements

The design of the local computing network is a rather complicated process. It begins with the development of a technical task, which should be thought out to be carefully thought out, since the shortcomings are threatened with subsequent difficulties in building a network and additional financial costs. Primary design can be made using special configurators that will allow you to choose optimal network equipment. Such programs are especially convenient to the fact that you can correct different values \u200b\u200band parameters directly during operation, as well as compile a report at the end of the process. Only after these actions can be proceeding for the next stage.

Sketch design

This stage is to collect data on the enterprise, where it is planned to install a locally computing network, and analyzing the information received. The number is determined:

Users.
Workstations.
Server rooms.
Connection ports.

An important point is the availability of data on ways of laying highways and planning a specific topology. In general, it is necessary to adhere to a number of requirements that the IEEE 802.3 standard places. However, despite these rules, it may sometimes be needed to calculate the signal propagation delays or consult the network equipment manufacturers.

The main characteristics of the LAN

Choosing a way to place communication nodes, it is necessary to remember the basic requirements for local networks:

Performance that combines several concepts: throughput, reaction time, transmission delay.
Compatibility, i.e. Abilities Connect different equipment of local computer networks and software.
Security, reliability, i.e. Opportunities to prevent unauthorized access and full data protection.
Scalability - the ability to increase the number of workstations without deteriorating network performance.
Managers - the ability to control the main elements of the network, prevention and elimination of problems.
The transparency of the network, which consists in representation for users with a single computing device.

The main topologies of locally computing networks: dignity and disadvantages

The network topology is a physical location, significantly affecting the main characteristics. On the modern enterprises Mainly use three types of topologies: "Star", "Tire" and "Ring".

The topology "Star" is the most common, has many advantages over the rest. This molding method is highly reliable; If any computer has failed (except for the server), the rest does not affect the rest of the rest.

Topology "Tire" is a single trunk cable with connected computing machines. A similar organization of the local computing network saves finance, but is not suitable for combining a large number of computers.

The "Ring" topology is characterized by low reliability due to the special location of the nodes - each of them is connected to two others using network cards. The breakdown of one computer leads to a stop of the entire network, so this type of topology is applied more and less.

Working design network

The local computing network of the enterprise also includes various technologies, equipment and cables. Therefore, the next stage will be the selection of all these elements. Deciding in favor of this or other software or hardware is determined by the purpose of creating a network, the number of users, a list of programs used, network sizes, and its location. Currently, fiber optic highways, characterized by great reliability, speed and availability are used.

About cable types

Cables are used in networks to transmit signals between workstations, each of them has its own characteristics that need to be taken into account when designing a LAN.

Twisted pair consists of several pairs of conductors coated with isolation and twisted among themselves. The low price and simplicity of installation are advantageous advantages, which makes such a cable as the most popular for mounting local networks.
Coaxial cable includes two conductors inserted one to another. The local computing network with the use of coaxial is no longer so common - it replaced the twisted pair, but it is found in some places so far.
Fiber optic is a glass thread capable of transferring light by reflecting it from the walls. The cable from this material transmits data to huge distances and is distinguished by high speed compared to twisted pair and coaxial, but it is expensive.

Necessary equipment

Network equipment of local computing networks includes a plurality of elements that are most common among which are:

Concentrator or hub. It combines some number of devices into one segment using a cable.
Switch. Uses special processors for each port, processing packets apart from other ports, due to which they have high performance.
Router. This is a device that makes decisions on packets based on data on routing tables and some rules.
Modem. It is widely used in communication systems, providing contact with other workstations through a cable or telephone network.

End network equipment

The hardware of the local computing network is mandatoryly included the server and client parts.

Server is powerful computerhaving high network importance. Its functions are to keep information, databases, user service and software processing. Servers are in special rooms with an adjustable constant air temperature - server, and the housing is equipped with additional protection against dust, accidentally shutdown, as well as a powerful cooling system. As a rule, only system administrators or executives of the enterprise have access to the server.

The workstation is a conventional computing machine connected to the network, that is, it is any computer that requests services from the main server. To ensure communication on such nodes, a modem and network fee are used. Since the server resources usually are used usually, client part Equipped with weak memory straps and hard disks of a small volume.

Software

Equipment of local computing networks will not be able to fully value their functions without suitable software. The program part includes:

Network operating systems on servers that make up the basis of any network. It is the OS that controls access to all network resources, coordinates the routing of packets, allows devices conflicts. These systems have built-in support for TCP / IP, NetBeUI, IPX / SPX protocols.
Autonomous OS, controlling the client part. They are the usual operating systems, for example, Windows XP, Windows 7.
Network services and applications. These software elements allow you to produce various actions: View remote documentation, printing on network printer, mailing mail messages. Traditional HTTP, POP-3, SMTP, FTP and Telnet services are the basis of this category and are implemented using software.

Local Nose Design Nuances

Designing a local computing network requires long and unhurried analysis, as well as accounting for all subtleties. It is important to provide for the possibility of an increase in the enterprise, which will entail and increase the scale of the local network. The project is necessary in such a way that the LAN at any time is ready to connect a new workstation or other device, as well as the upgrade of anyone node and component.

No less important security issues. The cable used in the construction of the network should be reliably protected from unauthorized access, and the highways are located away from potentially dangerous places where they may be damaged - inadvertently either intentionally. The components of the LAN, placed outside the room, must be ground and securely secured.

Development of a locally computing network is a fairly labor process, however, with the right approach and proper responsibility, the LAN will work reliably and stable, ensuring uninterrupted user work.

In the title, the local computing network has already laid the assignment, function and system limitations. We will analyze the name to the components. Local, formed from the English Local - local, that is, the network is tied to a specific geographical location and has restrictions on the territory, computing, associated with network composition (computing equipment, software) and its appointment, net - implies a combination of computing equipment and software on a certain territory (local) to the network (by means of cables).

In this way, it is possible to formulate a definition of a locally computing network (LAN) - this is a system of interconnected computing resources (computers, servers, routers, software, etc.) distributed by relatively small territory (office or group of buildings), serving for receiving and transfer, storage and processing information of various kinds.

Different locally computing networks can function individually or be interconnected using communications tools, such as enterprises with a branch network in different cities. Thanks to this connection, the user can interact with other workstations connected to this locally computing network. There are local networks whose nodes are separated by geographically at a distance of more than 12,500 km (space stations and orbital centers), but they still belong to local.

The assignment of the LAN is to ensure the joint and simultaneous access of a certain group of persons to data, programs and equipment (computers, printers, charts, file storage and processing devices, and databases) and data transmission (electronic graphics, text processing, email, access to remote bases data, digital speech transmission).

For example: the manager accepts an order and introduces it to the computer, then the order enters the accounting department and there is an invoice, at the same time information may come in legal service To create a contract.

Characteristics of LAN:

High-speed channels (1- 400 Mb С) belonging to predominantly one user;
The distance between workstations connected to the local network is usually from several hundred and several thousand meters;
Transmission of data between computer member stations;
Decentralization of terminal equipment, which uses microprocessors, displays, cash registers, etc.
Data transfer to subscribers connected to the network, on a shared cable;

The main functions of the LAN are:

Ensuring simultaneous access to equipment, software and information, combined into a network;
Minimizing the risk of unauthorized access to information and network resources;
Delimitation of access to information and network resources;
Ensuring fast and confidential exchange and simultaneous work with information to a certain circle of persons;
Control of information flows, including incoming and outgoing;
The distinction of control functions and responsible persons on each node (for each node corresponds to the system administrator performing the servicing and, as a rule, control functions);
Optimization of software and equipment costs due to their collective use (for example one printer into several departments, etc.)

As a result of the use of LAN unite personal computerslocated on many remote workplaces. Employee jobs cease to be isolated and combined into a single system that has its own special advantages:

The ability to remote access to equipment, software and information;
Optimization of processor operation resources;
Fewer errors intensity compared to the telephone database network;
Bandwidth higher than the global network;
The possibility of reconfiguration and development by connecting new terminals

Application area Local networks are very wide, currently there are such systems in almost every office (for example, one printer is installed on several computers, or several computers use one software, say 1C: Accounting, etc.). Every day, information flows are becoming more, the software used is comprehensive and functional, the geography of the activities of organizations is expanding. The use of LAN funds becomes not just desirable, but necessary for the successful activity and development of business, science, training of students, schoolchildren, training and retraining of specialists, the fulfillment of government programs and functions, etc.

Network functioning structure.

The structure of the local network is determined by the principle of management and communication type, it is often based on the structure of the serviced organization. Topology types are used: tire, annular, radial, tree. The most common two two types, due to effective use Communication channels, ease of management, flexible expansion and change capabilities.

Topology "Tire" - All computers are binding to a chain, connecting to a trunk cable segment (barrel), "Terminators" are placed at its ends, to clean the signal spreading in both directions. Computers in the network are connected coaxial cable with a tee connector. Network bandwidth is 10 Mbps, for modern applications that actively use video and multimedia data, this is not enough. The advantage of this topology lies in the low cost of posting and unification of connections.

Tire topology is passive. A failure of one computer does not affect network performance. Damage to the main cable (tires) leads to a reflection of the signal and the entire network as a whole becomes inoperable. Turning off and especially connection to such a network requires a tire break, which causes a violation of the circulating flow of information and the system freezing.

Topology "Tree" - A more advanced configuration of the type "tire". Several simple tires are attached to the common trunk bus through active repeaters or passive multipliers.

Topology "Star" (Star) - is the most high-speed of all topologies, information between peripheral workstations passes through the central node of the computing network. Central Control Node - file server It can implement the optimal protection mechanism against unauthorized access to information. The entire computing network can be controlled from its center.

The cable connection is pretty simple, as each workstation is connected only with the central node. The cost of laying cables is high enough, especially when the central node is geographically located not in the center of the topology. When expanding computing networks, previously performed cable connections cannot be used: a separate cable from the center of the network must be used to a new workplace.

In the case of a sequence configuration of the LAN, each configuration device to the physical environment transmits only one device only. At the same time, the requirements for transmitters and receivers are reduced, since all stations are actively involved in transmission.

Topology "Ring" (Ring) - Computers are connected by a cable segments having a ring shape, fundamentally identical to the tire, except for the need to use "Terminators". In the event of a malfunction of one of the network segments, the entire network fails.

Signals are transmitted only in one direction. Each station is directly connected to two adjacent, but listens to the transmission of any station. The ring is several transceivers and the physical environment connecting them. All stations may have equal access rights to the physical environment. At the same time, one of the stations can perform the role of an active monitor serving the exchange of information. The cable laying from one workstation to another can be quite complex and expensive, especially if geographically workstations are located far from the ring (for example, in line).

The main problem with the ring topology is that each workstation should actively participate in sending information, and in case of failure, at least one of them, the entire network is paralyzed. Faults in cable connections are easily localized. Connecting a new workstation requires a network shutdown, as the ring must be open during installation. Restrictions on the length of the computing network does not exist, as it ultimately is determined exclusively by the distance between the two workstations.

Computers can be connected with each other using different access media: copper conductors (twisted pair), optical conductors (optical cables) and through radio channels ( wireless technology). Wired, optical connections are installed via Ethernet, wireless - via Wi-Fi, Bluetooth, GPRS and other means. Most often local networks are built on ethernet technologies or Wi-Fi. It should be noted that the Frame Relay protocols were previously used, Token Ring.that today meet more and less often, they can be seen only in specialized laboratories, educational institutions and services.

Construction components of a simple local network are used:

Adapter (Network Adapter) - a device connecting the computer (terminal) with a network segment;
Bridge (Bridge) is a device connecting local or remote network segments;
Router (Router) - a device for limiting broadcast traffic by splitting the network to segments, ensuring information protection, management and organization of backup paths between broadcasting areas;
Switch - a narrowing device, effectively segmented network, reduces collision areas and increases the bandwidth of each terminal station.
Blocks uninterrupted power - Devices to ensure the operation of the system in cases of disconnecting the main power source.

Installation of the locally computing network (LAN)

The choice of the type of topology, the access environment and the locally computing system depends on the requirements and needs of the customer. Modern technologies allow you to develop an individual option that meets all the requirements and tasks.

The laying of LAN cables, as well as other types of cable networks can be carried out. different ways. When choosing a method of installation, it is guided by individual architectural and constructive features Buildings, It technical characteristics, the presence of existing networks and other equipment, the procedure for the interaction of low-current systems with other systems. You can fundamentally allocate two methods - open and hidden. For hidden wiring of LAN cables, the design of walls, floors, the ceilings are more aesthetic, the tracks are protected from extraneous influences, access to them is limited, the gasket is made immediately into special prepared places, the best conditions are provided for subsequent maintenance. Unfortunately, the ability to perform work with a hidden way is rare, more often it is necessary to carry out operating in the open method using plastic boxes, vertical columns and trays. Do not forget that there is still a way of laying cables by air, most often it is used to communicate buildings, when there is no possibility to pave the cable into the channels or if it is too expensive.

Installation of LAN is a complex and responsible work. The quality of its implementation depends the stability and correctness of the functioning of the system as a whole, the degree of execution of tasks assigned to it, the rate of transmission and data processing, the number of errors, etc. Factors. It is necessary to relate to this very thoroughly and seriously, since any network is the basis (skeleton and blood system) of the whole body from low-current systems responsible for a large number of functions (from email Before the safety of the object). Each subsequent intervention in the operation of the current system (expansion, repair, etc.), requires the cost of time and means, and their number on direct depends on the parameters initially laid down in the system, the quality of work performed, the qualifications of developers and performers. Saving funds at the design and installation of the LAN, can turn out much larger spending at the stage of operation and abgrade

The composition of local computing networks (LAN) of the enterprise (organization), their topology, protocols, resource allocation and access rights

Maintenance characteristics of LAN:

* The territorial length of the network (the length of the total communication channel);
* Maximum data transfer rate;
* Maximum number of ac network;
* the maximum possible distance between workstations on the network;
* network topology;
* View of the physical data environment;
* Maximum number of data channels;
* signal transmission type (synchronous or asynchronous);
* Method of access subscribers to the network;
* network software structure;
* Ability to transfer speech and video signals;
* Conditions for reliable networking;
* Ability to communicate LANs with each other and with a network more high level;
* Ability to use prioritization procedures while connecting subscribers to a common channel.

There are 2 local networks in the enterprise. One in the organization, and the other connects all migration services, domain access, each user has its own password.

Types of local networks.

All modern local networks are divided into two types:

· Peelling
· With centralized control.

In peer-to-peernetwork (peer-to-peernetwork) all computers are equal - each of the computers can be both the server and the client. The user of each of the computers itself decides which resources will be provided in total use and to whom.

In networks with centralized management, the security policy is common to all network users.

Topology Enterprise This Stars - Basic Topology computer networkIn which all network computers are attached to the central node (usually switch), forming a physical network segment. Such a network segment can function both separately and as part of a complex network topology (usually "tree"). The whole exchange of information goes exclusively through a central computer, which is in such a way a very large load is assigned, so it cannot be engaged in anything else. As a rule, it is the central computer that is the most powerful, and it is precisely all the functions for the exchange management. No conflicts on the network with a topology star are in principle are impossible, because the management is fully centrally.

Protocols of the organization:

The IPX / SPX and NetBIOS data transmission protocols are used.

The IPX protocol is the basic in NovellnetWare. It defines the format of packets transmitted over the network and interface with network software. At the IPX protocol level, workstations can exchange data blocks, and without confirmation of receipt.

The SPX protocol assumes that before the exchange of data, workstations establish communications among themselves. At the protocol level, the delivery of packet transmitted over the network. If necessary, repeated information packets are performed. The SPX protocol is a higher-level protocol.

NetBIOS protocol is designed to transfer data between workstations. It is a protocol of even higher level.

Sometimes B. local networks You can find the TCP / IP protocol. This protocol is based on operating system UNIX, and also used to transmit information between computers of a global computer network.