How to build a LAN is a local network of small enterprise. Local Web Construction Practice Description Project Scheme LAN Enterprise

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Planning a logical network structure Selection of a network topology and access methods Selecting a network architecture Planning a network structure with a reference to an enterprise. Estimation for the development and installation of the network. Computers included in LAN client - server architecture are divided into two types: workstations or clients are intended for users and file servers that are usually not available for regular users and are intended to manage network resources.

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Federal Agency for Education

State educational institution

Ufa State Aviation Technical University

In addition to the main component, the network may include uninterruptible power supplies, backup devices, modern dynamically distributed objects and various types of servers (such as file-servers, print servers or archive servers).

Creating a LAN, the developer is faced with a problem: with the known data on the purpose, the list of LAN functions and the basic requirements for a complex of technical and software LANs to build a network, that is, to solve the following tasks:

Determine the LAN architecture: Select the types of the LAN component;

Make an assessment of performance indicators of the LAN;

Determine the value of the LAN.

It should take into account the rules for the connection of the LAN components based on network standardization, and their limitations specified by manufacturers of the LAN component.

The LAN configuration for ACS significantly depends on the characteristics of a particular application area. These features are reduced to the types of transmitted information (data, speech, graphics), the spatial location of subscriber systems, information flow intensities, permissible information delays in transmission between sources and recipients, data processing volumes in sources and consumers, subscriber station characteristics, external climatic, electromagnetic factors, ergonomic requirements, requirements for reliability, the cost of LAN, etc.

The initial data for the design of the LAN can be obtained during the pre-project analysis of the applied area for which the ACS should be created. These data are then refined as a result of decision-making on the design stages of the LAN and the construction of increasingly accurate ACS models, which makes it possible to formulate requirements for it in the "technical task on the LAN". The best LAN is the one that meets all the requirements of users formulated in the technical task for the development of the LAN, with the minimum amount of capital and operating costs.

PURPOSE OF THE WORK

Obtaining topology selection skills, elements of a local computing network, as well as calculating the signal delay time.

Brief theoretical information

The design of the LAN configuration refers to the technical support stage of automated systems and is carried out at this stage after the distribution of the automated system on the LAN subscriber station, the selection of subscriber station types, determining the physical location of subscriber stations.

The design task includes the requirements for the LAN, indicating the available components of hardware and software, knowledge of the synthesis and analysis methods of the LAN, preferences and criteria for comparing the LAN configuration options. Consider the topology options and the composition of the component of the local computing network.

1. Topology LAN.

The topology of the network is determined by the method of connecting its nodes of communication channels. In practice, 4 basic topologies are used:

Star-shaped (Fig. 1);

Ring (Fig. 2);

Tire (Fig. 3);

Tree (Fig. 1 *);

Mesh (Fig. 4).

The topology of computing networks can be the most different, but only three are typical for local computing networks: ring, tire, star-shaped. Sometimes, the terms are used to simplify - ring, tire and star.

Tree topology (hierarchical, vertical). In this topology, the nodes perform other more intelligent functions than in the topology "Star". Network hierarchical topology is currently one of the most common. The network management software is relatively simple, and this topology provides a concentration point to manage and diagnose errors. In most cases, the network is controlled by the station A at the highest level of the hierarchy, and the distribution of traffic between stations is also initiated by station A. Many companies implement a distributed approach to the hierarchical network, in which in the system of subordinate stations each station provides direct control of stations that are lower in the hierarchy. From station A, controls stations B and C. This reduces the load on the LAN through the segment selection.

Mesh topology (mixed or multisoble). The network with a cellular topology is, as a rule, an unsoluted network of switching nodes of messages (channels, packages) to which the terminal systems are connected. All COPs are highlighted two-point. This type of topology is most commonly used in large-scale and regional computing networks, but sometimes they are used in LAN. The attractiveness of the cellular topology lies in relative resistance to overload and failures. Thanks to the multiplicity of paths from the station to the traffic station, the traffic can be sent bypassing refused or busy nodes.

The network topology affects reliability, flexibility, bandwidth, network cost, and response time (see Appendix 1).

The selected network topology should correspond to the geographical location of the LAN network, the requirements set for the network characteristics listed in the table. Topology affects the length of communication lines.

Fig.1. Star Topology Figure 2 Topology Ring

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Fig. 1 * Topology Distributed Star

Fig.3 Topology

linear tire

transparent "connection of several local networks or several segments of the same network with different protocols. Internal bridges connect most of the LAN using network cards in the file server. With an external bridge, a workstation is used as a service computer with two network adapters from two different, However, homogeneous computing networks.

In the case when the network connected differs across all control levels, the terminal system type is used. gateway, in which coordination is carried out at the level of application processes. Through firewall Systems using various operating environments and high levels protocols are connected

9. Source data for task

Users: Students, teachers, engineers, programmers, laboratory technicians, Department of Automated Ugate Management Systems.

Functions:

1) the implementation of the educational process on laboratory, practical exercises, the implementation of the course and thesis design;

2) organization of the educational process, preparation for classes, the development of methodological support;

3) Develop software for networking;

4) Prevention and repair of equipment.

Calculation of the cost of equipment LAN:

The LAN should allow connecting a large set of standard and special devices, including: computer, terminals, external memory devices, printers, plumbers, fax devices, control and control equipment, connecting equipment to other LANs and networks (including telephone) etc.

LAN should deliver data to a high degree of reliability (network availability ratio must be at least 0.96), must comply with existing standards, provide a "transparent" data transfer mode, allow a simple connection of new devices and turn off the old ones without disrupting the network of not more than 1 s ; The accuracy of data transfer must be no more + 1e-8.

11. List of tasks for the design of the LAN

11.1. Choose a LAN topology (and justify the choice).

11.2. Draw the LAN functional scheme and make a list of hardware.

11.3. Select optimal LAN configuration.

11.4. Make an indicative tracing of the cable network and calculate the length of the cable connection for the selected topology, taking into account the transitions between the floors. Since there are limitations to the maximum length of one segment of the local network for a specific type of cable and a given number of workstations, you need to establish the need to use repeaters.

11.5. Determine the delay in the distribution of packets in the designed LAN.

For calculations, it is necessary to highlight the path with the maximum double passing time and the maximum number of repeaters (hubs) between computers, that is, the maximum length path. If there are several such paths, then the calculation should be made for each of them.

The calculation in this case is carried out on the basis of Table 2.

To calculate the full double (circular) pass time for the network segment, you must multiply the length of the segment by the delay value of the meter, taken from the second column of the table. If the segment has a maximum length, then you can immediately take the maximum delay value for this segment from the third column of the table.

Then the delay in the segments included in the maximum length path must be summed up and added to this amount of the delay value for transceiver nodes of the two subscribers (these are three top lines of the table) and the values \u200b\u200bof delays for all repeaters (hubs) included in this path (these are three bottom lines Tables).

The total delay should be less than 512 bit intervals. It must be remembered that the standard IEEE 802.3u. Recommends to leave the reserve within 1 - 4 bite intervals to account for cables inside the connecting cabinets and measurement errors. It is better to compare the total delay with a value of 508 bite intervals, and not 512 bit intervals.

Table2.

Double network component delays Fast Ethernet (values \u200b\u200bof delays are given in bit intervals)

Type of segment	Metter delay	Max. delay
Two subscribers TX / FX.		Two subscribers TX / FX.
Two subscribers T4.		Two subscribers T4.
One subscriber T4. and one TX / FX.		One subscriber T4. and one TX / FX.



Shielded twisted para
Fiber optic cable
		Repeater (concentrator) class I
TX / FX.		Repeater (concentrator) class II with ports TX / FX.
Repeater (concentrator) class II with ports T4.		Repeater (concentrator) class II with ports T4.

All delays shown in the table are given for the worst case. If the time characteristics of specific cables, hubs and adapters are known, it is almost always preferable to use them. In some cases, this can give a noticeable increase to the permissible size of the network.

An example of calculation for the network shown in Fig. five:

There are two maximum paths: between computers (segments A, B and C) and between the upper (in drawing) with a computer and switch (segments A, B and D). Both of these paths include two 100 meter segments and one 5-meter. Suppose that all segments are 100Base-TX. and made on Cable Cable 5. For two 100 meter segments (maximum length) from the table, take the delay value of 111.2 bit intervals.

Fig 5. Example of the maximum network configuration Fast Ethernet

For a 5-meter segment when calculating a delay, 1,112 (delay per meter) is multiplied by a cable length (5 meters): 1,112 * 5 \u003d 5.56 bit intervals.

Delay value for two subscribers TX From the table - 100 bit intervals.

From the table of delays for two class II repeaters - 92 bitted intervals.

All listed delays are summed up:

111,2 + 111,2 + 5,56 + 100 + 92 + 92 = 511,96

this is less than 512, therefore, this network will be operational, although at the limit that is not recommended.

11.6. Determine the reliability of the LAN

For a model with two states (it works and does not work) the probability of the performance of the component or, it is easier to reliability, one can understand differently. The most common formulations are:

1. Availability of component

2. Reliability of component

Availability is used in the context of the working systems. From this it follows that the component can be in one of three states: it works, does not work, during the recovery process. The availability of the component is defined as the probability of its operation at a random point. An assessment of the amount of availability is made taking into account the average recovery time to the working condition and mean time in non-working condition. Reliability can be written:

______________average time to refusal ______________

average time to refusal + average recovery time

The quantitative values \u200b\u200bof the reliability of AIS should not be worse than the following:

The average time of operation for the failure of a software and hardware complex (KPTS) AIS should be at least 500 hours;

The average time of operational on the failure of a single channel of communication AIS should be at least 300 hours;

The average time of operation on the failure of the AIS servers should be at least 10,000 hours;

The average time of work on the refusal of PEVM (as part of AWP) should be at least 5000 hours;

The average time of operation for refusing a single function of application software (PPO) AIS KPTS should be at least 1500 hours;

The average recovery time of the efficiency of the AIS CCTS should be not more than 30 minutes; wherein:

The average recovery time of the efficiency of the CCTS after the refusals of the technical means should be - not more than 20 minutes, without taking into account the time of organizational downtime;

The average recovery time of the efficiency of the CCTS after the failure of the general or special software AIS is not more than 20 minutes without taking into account the time of organizational downtime;

The average recovery time of the operational communication channel of the CCTS should be not more than 3 hours;

The average recovery time of the efficiency of the CCTS in the event of a refusal or failure due to algorithmic errors of the application software of the software and technological complex (PTC) of the AIS, without the elimination of which is impossible to further functioning the CCTS or AIS PTC - up to 8 hours (taking into account the time to eliminate errors).

12.1. The list of stages of designing a LAN configuration indicating the projected design solutions.

12.2. LAN functional scheme (LAN drawing, indicating equipment stamps and communication lines). The scheme recommends noted the number of workstations in different segments of LAN, possible expansion reserves and "narrow" places.

12.3. The results of calculations of the value of the LAN (reduced to the table with the name of the name, the number of units, prices and cost). When calculating the cost to take into account the cost of designing and installing the LAN.

Name	amount	Cost	Note

12.4 Calculate LAN delay and reliability.

Appendix 1.

Table 1

Comparative data on the characteristics of the LAN

Characteristic	Qualitative evaluation of characteristics
Tire and tree	Ring network	Star network
Answer time test.	In the marker tire test. It is predictable and depends on the number of network nodes. In random bus t. ot. Depends on the load	test. There is a function from the number of network nodes	totv. depends on the load and temporal characteristics of the central node
Bandwidth WITH	The marker tire depends on the number of nodes. In random bus WITH Increases with sporadic small loads and falls when exchanging long messages in fixed mode	WITH falls when adding new nodes	WITH Depends on the performance of the central node and the bandwidth of the subscriber channels
Reliability	AU failures do not affect the performance of the rest of the network. The cable break displays the bus LAN.	The failure of one speaker does not lead to the failure of the entire network. However, the use of workarounds allows you to protect the network from the AC failures	AU failures do not affect the performance of the rest of the network. The reliability of the LAN is determined by the reliability of the central node

In a set of LAN communication lines set Included: bandwidth and data transfer rate, the ability to point, multipoint and / or broadcast transmission (that is, permissible applications), maximum length and number of connected subscriber systems, topological flexibility and complexity of gasket, resistance to interference and cost.

The main problem is to simultaneously provide indicators, for example, the highest data transfer rate is limited to the maximum possible data transmission distance, in which the required level of data protection is still ensured. Easy extension and simplicity of the expansion of the cable system affect its value.

The conditions of physical location help determine the best type of cable and its topology. Each type of cable has its own limitations at the maximum length: twisted para Provides work on short segments, single-channel coaxial cable - at long distances multichannel coaxial A fiber optic cable - At very long distances.

The data transfer rate is also limited by cable capabilities: the largest fiber optic Then go single-channel coaxial, multichannel cables and twisted couple. Under the required characteristics, you can choose the available cables.

Fast Ethernet 802.3u It is not an independent standard, but is an addition to the existing standard 802.3 in the form of chapters. New Fast Ethernet technology has kept all MAC. Level of classic EthernetBut the bandwidth was increased to 100 Mbps. Therefore, since the bandwidth increased 10 times, the bit interval decreased 10 times, and was now equal to 0.01 μs. Therefore, in technology Fast. Ethernet The transfer time of the minimum length of the minimum length in bit intervals remains the same, but equal to 5.75 μs. Restriction on the total length of the network Fast Ethernet decreased to 200 meters. All differences technology Fast Ethernet from Ethernet Focus on the physical level. Levels MAC. and LLC at Fast Ethernet Absolutely left the same.

The official standard 802.3u has established three different specifications for the physical level. Fast Ethernet:

- 100Base-TX. - for a two-party cable on unshielded twisted pair UTP. Category 5 or shielded twisted pair STP TYPE 1.;

- 100Base.-T4. - For a four-party cable on unshielded twisted pair UTP. categories 3, 4 or 5;

100Base-FX - for a multimode fiber optic cable, two fibers are used.

AT Ethernet 2 classes of concentrators are introduced: 1st grade and 2nd class. 1-class hubs support all types of physical layer coding ( TX, FX, T4), i.e. ports can be different. 2-class hubs support only one type of physical layer coding: either TX / FX.either T4..

Limit distances from the hub to the node:

- TX. - 100 m, FX. - Multimode: 412 m (half duplex), 2km (full). Single mode: 412 m (half duplex), up to 100 km (full), T4. - 100 m.

The chassis of the 1st class in the network can be only one, 2-class hubs - two, but M / D to 5 m.

Twisted pair (UTP)

The cheapest cable connection is a twisted twisted wire connection, often called twisted pair (twisted Pair.). It allows you to transmit information at a speed of up to 10-100 Mbps, it is easily increasing, however, it is noise-proof. The cable length cannot exceed 1000 m at 1 Mbps transmission rate. Advantages are low price and easy installation. To enhance the problems of information, the shielded twisted pair is often used. This increases the cost of twisted pair and brings its price to the price of a coaxial cable.

1. The traditional telephone cable, you can pass on it, but not data.

2. It is capable of transmitting data at a speed of up to 4 Mbps. 4 twisted pairs.

3. Cable capable of transmitting data at a speed of up to 10 Mbps. 4 twisted pairs with nine turns per meter.

4. Cable capable of transmitting data at a speed of up to 16 Mbps. 4 twisted pairs.

5. Cable capable of transmitting data at a speed of up to 100 Mbps. Consists of four twisted copper wire pairs.

6. The cable capable of transmitting data at a speed of up to 1 GB / s consists of 4 vital steam.

Coaxial cable It has an average price, noise immunity and is used to communicate over long distances (several kilometers). Information transfer rate from 1 to 10 Mbps, and in some cases it can reach 50 Mbps. Coaxial cable Used for basic and broadband information transfer.

Broadband coaxial cable Inexperial to interference, it is easy to increase, but its price is high. The speed transmission rate is 500 Mbps. When transferring information to the baseband frequency band for a distance of more than 1.5 km, an amplifier is required, or the so-called repeater ( rEPEATER). Therefore, the total distance during information transmission increases to 10 km. For computing networks with a tide topology or a coaxial cable tree should have at the end of the current resistor (Terminator).

Ethernet-cable It is also a coaxial cable with a wave resistance of 50 ohms. It is called back thick Ethernet (thick.) or yellow cable (yellow Cable.). It uses 15-pin standard inclusion. Due to noise immunity is an expensive alternative to ordinary coaxial cables. The maximum available distance without repeater does not exceed 500 m, and the total network distance Ethernet - about 3000 m. Ethernet-Cabel, due to its main topology, uses at the end of only one load resistor.

Cheaper than Ethernet-cabel, is the connection Cheagernet-cable Or, as it is often called, thin (thin.) Ethernet. It is also a 50-ohm coaxial cable with a speed transfer rate of 10 million bits.

When connecting segments Cheagernet-Cabel Repeators are also required. Computing networks S. Cheagernet- Cable have a small cost and minimum costs when building. The connection of network circuit boards is performed using widely used small bayonet connectors ( CP-50.). Additional shielding is not required. The cable joins the PC using tee connectors ( TConnectors.). The distance between two workstations without repeaters can be maximum of 300 m, and the total distance for the network on Cheapemet.-Cabel - About 1000 m. Transceiver Cheagernet located on the network board and is used both for galvanic junction between adapters, and to enhance the external signal.

The most expensive are opt rates Also called alone fiberglass cable. The speed of dissemination of information on them reaches several gigabits per second. External impact of interference is practically absent. Applied where electromagnetic fields of interference occurs or information is required for very long distances without the use of repeaters. They have contradictory properties, since the techniques of branches in fiber optic cables are very complex. Optic strokes are combined into a LAN with a star-shaped connection.

2 types of optical fiber:

1)single mode cable - A central conductor of small diameter is used, commensurate with a wavelength of light (5-10 μm). In this case, all rays of light spread along the optical axis of the fiber, without reflecting from the external conductor. The laser is used. Cable length - 100km and more.

2) Multimode cable - use broader internal cores (40-100 μm). In the internal conductor at the same time there are several light rays, reflected from the external conductor at different angles. The angle of reflection is called. Fashion ray. LEDs are used as a radiation source. Cable length - up to 2km.

LIST OF REFERENCES

Olifer network. Principles, technologies, protocols. - SPb.: Peter, 20c.

GUK, M. Local network hardware. Encyclopedia.- SPB. : Publishing house Peter, 2004.- 576 p.

Novikov, Networks: Architecture, Algorithms, Design. - M.: Ekom, 2002.- 312c. : IL. ; 23cm. - ISBN -8.

Pepaneshnikov, Computing Networks /, .- Moscow: Dialog Mafi, 2005.- 224 p.

1. http: // ***** /, System for automatic creation of projects of local computing networks
Compilers: Nikolai Mikhailovich Dubinin

Ruslan Nikolaevich Agapov

Gennady Vladimirovich Startsev

Local System Design

Laboratory workshop on discipline

"Networks of computer and telecommunications"

Signed in the seal of the XX.05.2008. Format 60x84 1/16.

Offset paper. Flat printing. Headset Times New Roman.

Sl. Pechs. l. . Sl. kr. - Ot. . Uch. - ed. l. .

Circulation 100 copies. Order No.

GOU VPO Ufa State Aviation

technical University

Center for Operational Printing Ugatu

Ufa Center, ul. K. Marx, 12

The number of Internet users is constantly growing. Modern technologies allow you to solve a variety of tasks of receiving and transmitting data from various types - from texts to video, music and images.
In this regard, there is a need for the right organization of local computing networks. Designing local networks requires careful planning at all stages.
Can contact both wired, so wireless.

Stages of design and construction of the LAN

Several stages can be distinguished:

primary study
development, drafting
preparation of equipment
montage LAN
warranty and post-warranty service

Necessary properties of local networks

Scalability of LAN

Maschatabirost is a necessary property that needs to be provided in the design of the LAN. At the initial stage of the organization must meet the necessary goals and objectives. But it is necessary to take into account the possibility of expanding the LAN so that in the future you can connect additional equipment.

Flexibility

The presence of flexibility is necessary for the rapid response of the LAN for changing requirements. LAN should adapt normally for various types of network cables. The concept of flexibility also includes support for various technologies from Ethernet, Fast Ethernet and to Gigabit Ethernet.

fault tolerance

Failure tolerance is a very important property that is important to provide for design. The issue of fault tolerance is solved with the help of backup lines, which will be involved in the case of the failure of the main networks. There is a server connection option to concentrators equipped with spare paths. If one concentrator fails, you can always quickly go to another in automatic mode, without interrupting the communication session.

Reliability of LAN

It is necessary to look for optimal options for long-term use of a local computer network. Forced downtime costs expensive, so it is necessary to use special devices and tools, improving the reliability of the LAN.

Protection LAN

The guarantee of reliable and efficient operation of the company and the preservation of data is the security of local computing networks. Competently designed local computing networks should provide protection against unauthorized access via a telephone line or Internet.
A simple password does not provide reliable protection, so to ensure more efficient protection, the level of the hub, switch, router and remote access server. The use of such methods to protect the LAN provides the ability to complete the current processes and ensures the safety of the most important data of the organization.

Managing LAN

The capabilities of powerful tools for monitoring a local computing network are used to quickly diagnose and eliminate interference and malfunction to eliminate the possible downtime mentioned above. There are many products used to collect parameters on the status of the LAN and its parameters, for example, RMON. The Web interface provides the ability to control the family almost anywhere using remote access.
, ensuring their manageability and other properties should be carried out only by specialists who have qualifications and experience Work in the design and installation of LAN.

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Introduction

1.6 Technology selection
Conclusion

Introduction

The subject of my course work was the process of designing a local computing network. This topic is quite relevant, as it is due to the worldwide tendency to combine computers on the network. Computer computing network is a combination of computers connected by link lines. Cables, network adapters and other communication devices are called lines. It can be said that all network equipment runs under the control of application software.

The relevance of the topic is determined by the fact that computer networks firmly entered our lives. They apply in almost all spheres of life: from learning to production management, from settlements on the stock exchange to home Wi-Fi network. On the one hand, they are a special case of distributed computer systems, and on the other, can be considered as a means of transmitting information over long distances, for which they use coding and multiplexing methods to develop in various telecommunication systems.

Purpose: Design a local computing group of computer classrooms.

Research Object: The process of designing a local computing network.

The research methods that are to systematize and analyze educational and regulatory and technical literature, as well as the Internet resource, recommendation of manufacturers of telecommunications equipment and modern standards.

Research Subject: Search and processing knowledge about the research subject will be carried out using educational materials specified in the list of literature and network resources.

Tasks of work:

1. Theoretical rationale Building a computing local network;

2. Earware of the prerequisites and conditions for creating a computer network;

3. Creating a project of a computing local network.

1. Theoretical substantiation of building a computing local network

1.1 Local and global networks. Networks of other classification types

In order to create a LAN project, first of all, first of all, it is primarily to determine how the LAN differs from other types of networks.

The local computing network is a system of distributed data processing, covering a small territory (diameter up to 10 km) inside agencies, universities, banks, offices, etc.

· Pan is a personal network intended for the interaction of various devices belonging to one owner.

· LAN (LAN), - local networks that have a closed infrastructure before accessing service providers. The term "LAN" can also describe a small office network, and a network of a large plant. Local networks are closed-type networks, access to them is allowed only by a limited circle of users, for which work in such a network is directly related to their professional activities.

· CAN (campus network) - combines local networks closely located buildings.

· Man - urban networks between institutions within one or more cities connecting many local computing networks.

· WAN is a global network covering large geographic regions, including both local networks and other telecommunication networks and devices.

· The term "corporate network" is also used in the literature to designate a combination of several networks, each of which can be built on various technical, software and information principles.

By way of control

TOlitting / server - they allocate one or more nodes (their names - servers) performing managers or special service functions on the network, and the rest of the nodes (clients) are terminal, users work in them. Networks client / server differ in the character of the distribution of functions between servers, in other words by server types. When specializing servers on specific applications we have a network of distributed computing. Such networks are also distinguished from centralized systems built on mainframes;

Peer-to-peer-networks in them all nodes are equal to them; Since, in general, under the client it is understood as an object (device or program) requesting some services, and under the server - an object that provides these services, then each node in peer-to-peer networks can perform functions and client, and server.

By the access method

T.drive data transfer media in local computing networks - segment (segment) of the coaxial cable. Nodes are connected to it through the data channel ending equipment, computers are connected and the total peripheral equipment is possible. Since the data transmission medium is general, and the network exchange requests from nodes appear asynchronously, then the problem of separation of a common environment between many nodes, in other words, the problem of providing access to the network occurs. Network Access - Station Interaction (Network Node) with data transfer medium to exchange information with other stations. Environmental Access Control is to establish a sequence in which the stations get access to the data transfer medium. Distinguish random and deterministic access methods. Among the random methods is the most famous method of multiple access with the control of carrier and detection of conflicts.

1.2 Comparative analysis of various network topologies

At the moment there are ways to combine computers. The method of describing the network configuration, the location diagram and connection of network devices is characterized by the term network top-rolled.

We highlight the most common network topologies:

Bus - a local network in which the connection between any two stations is set through one shared path and data transmitted by any station simultaneously becomes available for all other stations connected to the same data transmission medium.

Ring - nodes are associated with a ring line of data transfer (only two lines are suitable for each node); data passing through the ring, alternately become available to all network nodes;

Star - there is a central node, from which the data lines are diverged to each of the other nodes;

Hierarchical - Each device provides direct control of devices below in the hierarchy.

The term "topology", or "network topology", characterizes the physical location of computers, cables and other network components.

Topology is a standard term that is used by professionals when describing the main network layout. In addition to the term "topology", the following is also used to describe the physical layout:

Physical location; layout;

Diagram;

The network topology causes its characteristics. In particular, the choice of one or another topology affects:

On the composition of the necessary network equipment;

Network equipment characteristics;

Network expansion capabilities;

Method of network management.

To share resources or perform other network tasks, computers must be connected to each other. For this purpose, cable is used in most networks.

However, simply connect the computer to the cable connecting other computers, not enough. Different types of cables in combination with various network cards, network operating systems and other components require various mutual positions of computers.

Comparative analysis of networking topologies

Comparative analysis was conducted on the basis of the following indicators:

1) simplicity of a structural organization. Measured by the number of communication channels between network nodes

2) reliability. Determined by the presence of bottlenecks, if the network fails to function. Reliability is also characterized by the presence of alternative paths due to which, when refusing separate channels, communication can be established bypassing the refused area

3) network performance. Determined by the number of data blocks transmitted over the network per unit of time. It is necessary to take into account the possibility of reducing speed due to conflicts on the network

4) Message delivery time. It may not be measured in temporary units.

5) the cost of topology. Determined by both the cost of equipment and the complexity of the network implementation.

We will make a table of comparing various topologies on the specified features. Signs will be evaluated by values \u200b\u200bfrom 1 to 5, and 1 is the best value.

Table 1

Comparative analysis of network topology

The simplicity of the structural organization and cost are two indicators that are very dependent on each other. By the number of communication channels, the most simple topologies is the total tire, which has only 1 communication channel. The network is based on a network card. The lack of difficulties in adding new computers, also adds the advantages of this topology. Thus, the total tire is undoubtedly the simplest and cheap topology. The topologists of the star and wood can also be attributed to the relatively cheap, which is associated with a small number of types of connections between nodes, i.e. Each computer is connected directly to the central node. Next follows the Topology Ring. In it, the number of communication channels is equal to the number of nodes. Completely connected topology is the most difficult, and expensive, respectively. This makes it inappropriate to use such a topology when building large networks. When building global networks, a multi-associated \\ cellular topology was most widely distributed. It occupies an intermediate position in these indicators, but there are no alternatives to this topology in global networks, because such networks are not built from scratch, and unites existing networks.

Reliability. According to this indicator, the leader is a complete connection topology. She does not have bottlenecks and there is a maximum possible amount of alternative ways when the link is output. The least reliable topology: total tire, star and tree. Topology Ring occupies an intermediate position, as well as multisycle.

Network performance. If you use the number of packets transmitted in the network per unit of time as a unit of measurement of performance, then it is obvious that the performance will be the higher the more packets simultaneously on the network. With an increase in the number of packages, the performance grows and with some kind of value is saturation. The saturation is usually associated with some node or channel on the network, the load of which is approaching 1. Therefore, when building such a network, it is trying to ensure equal bandwidth for all channels, which ensures maximum performance for complete-link topology and minimal performance for the total tire.

Delivery time. It is necessary to analyze if there are no bottlenecks on the network. In this case, the delivery time is directly connected with the number of hops, i.e. Communication channels between adjacent nodes. Delivery time in 1 Hop provides complete connection topology. The greatest delivery time with a large number of nodes on the network with the Topology Ring. It is most difficult to estimate the delivery time in the topology Total bus. This is due to the fact that the bus is used by all uzami, and if the delivery time is minimal for one node, then other nodes are waiting for their turn, and the delivery time increases sharply. In addition, the topology of the total bus for the delivery time has an impact of collisions, i.e. Package collisions.

The presented analysis is qualitative and cannot be used for quantitative assessment. The decision to use this or that topology should be made on the basis of accounting for all parameters. It may turn out that a more complex topology is cheaper than simple.

Based on the material material, it was decided to apply the "Star" topology, as it has the greatest efficiency of the presented.

1.3 Analysis of sources Standardization of networks. IEEE 802.x Structure Structure

In 1980, the IEEE Institute was organized at the IEEE Institute for Local Network Standardization, as a result of which the IEEE 802-X Family was adopted, which contain recommendations for the design of the lower levels of local networks. Later, the results of the work of this committee formed the basis of the international standards of ISO 8802-1 ... 5. These standards were created on the basis of very common branded Ethernet network standards, ArcNet and Token Ring.

The standards of the IEEE 802.x family cover only the two lower levels of the seven-level OSI model - physical and channel. This is due to the fact that it is these levels that most reflect the specifics of local networks. The older levels starting with the network, largely have general features for both local and global networks.

The specificity of local networks also reflected in the separation of the channel layer into two supremes, which are also often called levels. The channel level is divided into local networks into two suits:

Logical data transmission (LOGICAL Link Control, LLC);

MEDIA ACCESS CONTROL, MAC).

The MAC layer appeared due to existence in local networks of a shared data transfer medium. It is this level that provides the correct sharing of a common environment, providing it in accordance with a certain algorithm to order a network of network. After access to the medium is obtained, it can use a higher level - the LLC level that organizes the transmission of logical data units, information frames, with a different level of quality of transport services. In modern local networks, several Mac level protocols that implement various access algorithms for the shared medium were distributed. These protocols fully determine the specifics of technologies such as Ethernet, Fast Ethernet, Gigabit Ethernet, Token Ring, FDDI, L00VG-Anylan.

The LLC level is responsible for transmitting data frames between nodes with varying degrees of reliability, implements the interface features with a network level adjacent to it. It is through the LLC level that the network protocol requests the supply operation with the necessary quality from the channel level.

Mac and LLC level protocols are mutually independent - each MAC level protocol can be used with any LLC level protocol, and vice versa.

IEEE 802 standards have a fairly clear structure indicated in Figure 1.1.

Figure 1.1.

Today, the 802 Committee includes the following a number of subcommittees, which includes both already mentioned and some others:

802.1 - InternetWorking - network merging;

802.2 - Logical Link CONTROL, LLC - managing logical data transfer;

802.3 - Ethernet with CSMA / CD access;

802.4 - Token Bus LAN - Local networks with access method TOKEN BUS;

802.5 - Token Ring LAN - Local networks with access method TOKEN Ring;

802.6 - Metropolitan Area Network, MAN - Methods of Megacols;

802.7 - Broadband Technical Advisory Group - Technical Consulting Group on Broadband;

802.8 - Fiber Optic Technical Advisory Group - Technical Consulting Group on Fiber Optic Networks;

802.9 - INTEGRATED VOICE AND DATA NETWORKS - Integrated voice and data transmission networks;

802.10 - Network Security - Network Security;

802.11 - Wireless Networks - Wireless Networks;

802.12 - Demand Priority Access LAN, L00VG-AnyLAN - Local networks with access on request with priorities.

On the basis of the analysis performed, it was decided to use the following Subcommittee IEEE 802.3 when designing a local computing network. The specification of this subcommittee will be discussed below.

1.4 Study of the elements of a structured cable system (SCS)

The cable system is the foundation of any network. A structured cable system has become a response to high demands for the quality of the cable system.

The structured cable system is a set of communication elements - cables, connectors, connectors, cross panels and cabinets that satisfy standards and allow you to create regular, easily expandable link structures.

The structured cable system consists of three subsystems: horizontal (within the flood), vertical (between floors) and campus subsystem (within one territory with several buildings).

For the horizontal subsystem, the presence of a large number of branches and cross-links is characterized. The most appropriate type of cable is the unshielded twisted pair of category 5.

The vertical subsystem consists of more extended cable segments, the number of branches is much smaller than in the horizontal subsystem. The preferred type of cable is fiber optic.

For the campus subsystem, the irregular structure of ties with the central building is characteristic. The preferred type of cable is a fiber optic in a special isolation.

The cable system of the building is composed of redundant, since the value of the subsequent expansion of the cable system exceeds the cost of installing excess elements.

For the construction of the SCS, switches or hubs are almost always used. In this regard, the question appears - what device to use?

When transferring data between computers, the package contains not only transmitted data, but also the address of the recipient's computer.

The hub ignores the address contained in the package and forwards data to all computers connected to it. The hub bandwidth (the number of bits per second, which is capable of transmitting the concentrator) is divided between the ports involved, since the data is transmitted to everyone at the same time. The computer reads the address, and only a legitimate recipient receives a data packet (the remaining computers ignore it).

The switch works more intelligently - it stores information about computers in memory and knows where the recipient is located. The switch transmits data to the port of this computer and serves only this port.

This is an extremely simplified description of the principles of hubs and switches, but it gives a general idea of \u200b\u200bthe process. Also note that a very simple switch is described here, whereas more advanced technologies exist for powerful switches used in large networks.

By the way, in routers there are built-in switches, not hub. .

Based on the information, it was decided to use switches (switches) when building a network.

1.5 Cable selection. Main types of cables and their characteristics

Category 1 cables are used where requirements for transmission rate are minimal. This is usually a cable for digital and analogue voice and low-speed (up to 20 kbps) data transmission.

Category 2 cables were first applied by IBM in constructing their own cable system. The main requirement for the cables of this category is the ability to transmit signals with a spectrum of up to 1 MHz.

Cable Categories 3 were standardized in 1991, when the standard of telecommunication cable systems for commercial buildings was developed (EIA-568), on the basis of which the current EIA-568A standard was created. The EIA-568 standard has determined the electrical characteristics of Cable Cable 3 for frequencies in the range of up to 16 MHz, thus supporting high-speed network applications. Category 3 cable is designed for both data transmission and voice transmission.

Category 4 cables are a slightly superior version of Cable Cables 3. Category 4 cables are required to withstand tests at a signal transmission frequency of 20 MHz and ensure increased noise immunity and low signal loss. Category 4 cables are well suited for use in systems with increased distances (up to 135 meters) and in TKen Ring networks with a bandwidth of 16 Mbps. In practice, it is rarely used.

Category 5 cables were specifically designed to support high-speed protocols. Therefore, their characteristics are determined in the range of up to 100 MHz. Most of the new high-speed standards are focused on the use of twisted pair of 5 categories. On this cable, protocols are working with a data transfer rate of 100 Mbps - FDDI, Fast Ethernet, L00VG-Anylan, as well as more speed protocols - ATM at 155 Mbps speed, and Gigabit Ethernet at 1000 Mbps speed (Gigabit Ethernet version On twisted pair of category 5 became the standard in June 1999). Cable Category 5 came to replace the Cable Cable 3, and today all new cable systems of large buildings are based on this type of cable (in combination with fiber optic).

The most important electromagnetic characteristics of the Category 5 cable have the following values:

Full wave resistance in the frequency range up to 100 MHz is 100 ohms;

The magnitude of the crosspin NEXT, depending on the signal frequency, should receive values \u200b\u200bof at least 74 dB at a frequency of 150 kHz and at least 32 dB at a frequency of 100 MHz;

The attenuation has limit values \u200b\u200bfrom 0.8 dB (at a frequency of 64 kHz) to 22 dB (at a frequency of 100 MHz);

Active resistance should not exceed 9.4 Ohm per 100 m;

Cable capacity should not exceed 5.6 NF per 100 m.

All UTP cables regardless of their category are manufactured in a 4-pair version. Each of the four pairs of the cable has a certain color and twist step. Usually, two pairs are intended for data transmission, and two - for voice transmission.

For connecting cables with equipment, the RJ-45 plugs and sockets representing 8-pin connectors similar to the usual telephone connectors are used. RJ-11.

This information allows us to conclude that the UTP cable of the 5th category is most preferable to build a local network. .

1.6 Technology selection

1.6.1 Ethernet technology. Ethernet technology frames and formats

Consider How the general approaches described above are embodied in the most important problems of building networks are embodied in the most popular network technology - Ethernet.

Network technology is a consistent set of standard protocols and implementing their software and hardware (for example, network adapters, drivers, cables and connectors), sufficient to build a computer network. The epithet "sufficient" underlines the fact that this set is a minimum set of funds with which you can build a working network. It is possible that this network can be improved, for example, by selecting subnets in it, which immediately requires an Ethernet protocol application applications, as well as special communication devices - routers. The improved network will most likely, more reliable and high-speed, but due to the add-ons over the means of Ethernet technology, which was the network basis.

The term "network technology" is most often used in a narrow sense described above, but sometimes its advanced interpretation is also used as any set of funds and rules for building a network, for example, "Through Routing Technology", "Protected Channel Technology", "IP Technology Networks. "

Protocols, on the basis of which a network of specific technology is built (in a narrow sense), specially developed for collaboration, therefore, the network developer does not require additional efforts to organize their interaction. Sometimes network technologies are called basic technologies, having in mind that based on them is based on the basis of any network. Examples of basic networking technologies can serve as an Ethernet such well-known local networking technologies like, token Ring and FDDI, or technology of territorial networks X.25 and Frame Relay. To obtain a working network, in this case, it is sufficient to purchase software and hardware related to one basic technology - network adapters with drivers, hubs, switches, cable system, etc., - and connect them in accordance with the requirements of the standard for this technology. The basic principle based on Ethernet is the random access method to the shared data transfer medium. As such a medium, a thick or thin coaxial cable, twisted pair, fiber optic or radio wave (by the way, the first network, built on the principle of accidental access to the shared medium, was the radio network of Aloha Hawaiian University).

In the Ethernet standard, the topology of electrical connections is strictly recorded. Computers are connected to the shared medium in accordance with the typical "total bus" structure. Using the bus-shared bus, any two computers can exchange data. Control access control is carried out by special controllers - Ethernet network adapters. Each computer, and more accurately, each network adapter has a unique address. Data transmission occurs at a speed of 10 Mbps. This value is the bandwidth of the Ethernet network. Initially, the Ethernet network looked like this (Fig. 1.2)

Figure 1.2.

Access method

The essence of the random access method is as follows. The computer in the Ethernet network can transmit data over the network only if the network is free, that is, if no other computer is currently engaged in the exchange. Therefore, an important part of the Ethernet technology is the procedure for determining the availability of the medium.

After the computer was convinced that the network is free, it starts the transmission, while "captures" medium. The monopoly time of the shared medium in one node is limited to the transmission time of one frame. Frame is a data unit that exchanges computers in the Ethernet network. The frame has a fixed format and along with the data field contains various service information, such as the recipient address and the sender's address.

The Ethernet network is designed so that when the frame in the shared data transmission medium, all network adapters are simultaneously starting to take this frame. All of them analyze the destination address located in one of the initial fields of the frame, and, if this address coincides with their own address, the frame is placed in the internal buffer of the network adapter. Thus, the addressee computer receives the data intended for it. .

Format personnel

There are several Ethernet formats.

Initial Version I (no longer applied).

Ethernet Version 2 or Ethernet-frame II, which is also called DIX-- most common and used to this day. It is often used directly to the Internet protocol.

Figure 1. 3. Ethernet frame format

The most common format of Ethernet II frame

Novell - Internal modification of IEEE 802.3 without LLC (Logical Link Control).

IEEE 802.2 LLC frame.

IEEE 802.2 LLC / SNAP frame.

Some Ethernet Network Cards manufactured by Hewlett-Packard have been used by IEEE 802.12 format frame, which corresponds to the 100VG-AnyLAN standard.

As an Ethernet Frame Supplement, an IEEE 802.1Q tag may contain the VLAN identification to which it is addressed, and IEEE 802.1p to indicate priority.

Different types of frame have a different format and MTU value.

Based on this information for the local network of the building under consideration in the course work, Ethernet technology was selected.

1.6.2 High-speed computer networking technologies: Fast Ethernet, Gigabit Ethernet, 10G Ethernet

Everything The differences between the Fast Ethernet technology from Ethernet are focused on the physical level. Mac and LLC levels in Fast Ethernet remained absolutely the same, and they are described by the previous chapters of standards 802.3 and 802.2. Therefore, considering FAST Ethernet technology, we will study only a few options for its physical level.

The more complex structure of the physical level of FAST Ethernet technology is caused by the fact that it uses three options for cable systems:

Fiber optic multimode cable, two fibers are used; Local computing network cable

Coaxial cable, which gave the first Ethernet network, in the number of allowed data transmission media Fast Ethernet did not hit. This is a general trend of many new technologies, because at short distances, twisted pair of category 5 allows you to transmit data at the same speed as a coaxial cable, but the network is cheaper and more convenient to operate. At large distances, the optical fiber has a much broader bandwidth than the coaxial, and the network costs turns out not much higher, especially considering the high costs of troubleshooting and troubleshooting in a large cable coaxial system.

Below in the figure shows the differences of Fast Ethernet and Ethernet technology from each other.

Figure 1.4.

Gigabit Ethernet.

The main idea of \u200b\u200bthe developers of Gigabit Ethernet consisted of maximizing the ideas of Ethernet technology while reaching 1000 MB / S, saving all Ethernet frame formats. There is still a half-addix version of the protocol that supports the CSMA / CD access method. Saving the cheapness of solutions based on a shared environment allows you to apply Gigabit Ethernet in small working groups that have quick servers and workstations. All major types of cables used by Ethernet are supported in Fast Ethernet fiber optic, twisted pair of category 5, unshielded twisted steam.

10-Gigabit Ethernet.

The new standard 10-gigabit Ethernet includes seven physical environment standards for LAN, MAN and WAN. Currently, it is described by the IEEE 802.3ae amendment and must enter the following audit of the IEEE 802.3 standard.

10GBase-CX4 - 10-gigabit Ethernet technology for short distances (up to 15 meters), CX4 copper cable and InfiniBand connectors are used.

10GBase-SR is a 10-gigabit ethernet technology for short distances (up to 26 or 82 meters, depending on the type of cable), a multimode fiber is used. It also maintains distances up to 300 meters using a new multimode fiber (2000 MHz / km).

10GBase-LX4 - uses a wavelength seal to support distances from 240 to 300 meters along multimode fiber. Also supports distances to 10 kilometers when using single-mode fiber.

10GBase-LR and 10GBase-ER - These standards maintain distances up to 10 and 40 kilometers, respectively.

10GBase-SW, 10GBASE-LW and 10GBase-EW - These standards use a physical interface that is compatible with the speed and data format with the OC-192 / STM-64 SONET / SDH interface. They are similar to 10GBase-SR, 10GBase-LR and 10GBase-ER standards, respectively, as they use the same types of cables and transmission distance.

10GBase-T, IEEE 802.3an-2006 - adopted in June 2006 after 4 years of development. Uses twisted pair of category 6 (maximum distance of 55 meters) and 6a (maximum distance of 100 meters).

10GBase-KR - 10-gigabit Ethernet technology for cross-boards (backplane / midplane) modular switches / routers and servers (MODULAR / BLADE).

Harting announced the creation of the world's first 10-gigabit RJ-45 connector that does not require installation tools - Harting RJ Industrial 10G.

1.6.3 Local Networks based on Shared Environment: TECKENRING TECHNOLOGY, FDDI technology

Shared Wednesday - The method of organizing the work of the network, in which the message from one workstation reaches all others with one common communication channel.

The access algorithm for the shared environment is the main factor that determines the efficiency of sharing the medium to the local networks. It can be said that the access algorithm forms the "appearance" technology, allows you to distinguish this technology from others.

Ethernet technology applies a very simple access algorithm that allows the network node to transmit data to those moments when he believes that the divided environment is free. The simplicity of access algorithm has identified the simplicity and low cost of Ethernet equipment. The negative attribute of the Ethernet technology access algorithm is collisions, that is, situations where frames transmitted by different stations face each other in the overall environment. Collisses reduce the effectiveness of the shared environment and give the network to the network unpredictable.

The initial version of Ethernet technology was designed for a coaxial cable that was used by all nodes of the network as a common tire. The transition to cable systems on a twisted pair and concentrators (hubs) has significantly increased the operational characteristics of Ethernet networks.

In TECKEN RING and FDDI technologies, more complex and efficient access algorithms were maintained, based on transferring to each other tokens - a special frame allowing access. However, to survive in the competitive struggle with Ethernet, this advantage was not enough.

TECKEN RING TECHNOLOGY (802.5)

TKEN Ring networks, as well as Ethernet network, characterizes a shared data transfer environment, which in this case consists of cable segments connecting all network stations in the ring. The ring is considered as a general shared resource, and it requires an accidental algorithm for access to it, but a deterministic, based on the transfer of the right to use the rings in a certain order. This right is transmitted using a special format frame called a marker or token (TOKEN).

TKEN Ring networks operate with two bit rates - 4 and 16 Mbps. Mixing stations operating at different speeds in one ring is not allowed.

TKEN Ring technology is more complex technology than Ethernet. It has the properties of fault tolerance. The token Ring network defines network control procedures that use the feedback of the ring-shaped structure - the sent frame is always returned to the station - the sender.

To control the network, one of the stations performs the role of the so-called active monitor. The active monitor is selected during the initialization of the ring as a station with the maximum value of the MAC address, if the active monitor fails, the ring initialization procedure is repeated and a new active monitor is selected. In order for the network to detect an active monitor failure, the last in the working condition every 3 seconds generates a special frame of its presence. If this frame does not appear on the network for more than 7 seconds, the rest of the network stations begin the procedure of elections of the new active monitor.

FDDI

FDDI technology - Fiber optic interface of distributed data is the first technology of local networks in which the data transmission medium is a fiber optic cable. FDDI technology is largely based on TOKEN Ring technology, developing and improving its main ideas. The developers of the FDDI technology set themselves as the most priority objectives:

Increase the bit rate of data transfer up to 100 Mbps;

Increase the fault tolerance of the network due to standard procedures for restoring it after the failures of various kind - damage to the cable, incorrect operation of the node, hub, the occurrence of a high level of interference on the line, etc.;

Maximum effectively use the potential network bandwidth for asynchronous and synchronous (delay sensitive) traffic.

The FDDI network is based on two fiberglass rings that form the main and backup data transmission path between network nodes. The presence of two rings is the main way to improve fault tolerance in the FDDI network, and nodes that want to take advantage of this increased reliability potential must be connected to both rings.

In the normal network operation mode, the data passes through all the nodes and all the sections of the cable only primary (PRIMARY) rings, this mode is called the Thru - "cross-cutter" or "transit" mode. The secondary ring (SECONDARY) is not used in this mode.

In the event of a type of failure, when a part of the primary ring cannot transmit data (for example, a cable break or a node failure), the primary ring is combined with the secondary re-forming a single ring. This network mode is called WRAP, that is, "coagulation" or "folding" rings. The coagulation operation is performed by means of hub and / or FDDI network adapters. To simplify this procedure, data on the primary ring is always transmitted in one direction (on the diagrams this direction is depicted counterclockwise), and on the secondary - in the opposite (depicted clockwise). Therefore, when the common ring of two rings is formed, the stations transmitters still remain connected to the receivers of adjacent stations, which allows you to correctly transmit and receive information to neighboring stations. .

1.7 Analysis of the Specifications of the Physical Environment FAST Ethernet

Specifications of the 802.3z Physical Environment

The following types of physical environment are defined in Standard 802.3z:

Single mode fiber optic cable;

Multimode fiber optic cable 62.5 / 125;

Multimode fiber optic cable 50/125;

Double coaxial with a wave resistance of 75 ohms.

Multimode cable

To transfer data to traditional computer networks, a multimode fiber optic cable standard determines the use of emitters operating on two wavelengths: 1300 and 850 nm. The use of LEDs with a wavelength of 850 nm is due to the fact that they are much cheaper than LEDs operating on a wavelength of 1300 nm, although the maximum cable length decreases, since the attenuation of multimode fiber opens on the wave of 850 m more than twice as much as on Wave 1300 nm. However, the possibility of cheaper is extremely important for such an entirely expensive technology as Gigabit Ethernet.

For multimode optical fiber, the standard 802.3z defined the L000Base-SX and L000Base-LX specification.

In the first case, the wavelength of 850 nm is used (s means Short Wavelength, a short wave), and in the second - 1300 nm (L - from Long Wavelength, a long wave).

For the L000Base-SX specification, the limit length of the fiber optic segment for cable 62.5 / 125 leaves 220 m, and for a cable 50/125 - 500 m. It is obvious that these maximum values \u200b\u200bcan be achieved only for full-duplex data transmission, as the double turnover time On two sections of 220 m is 4400 Bt, which exceeds the limit of 4095 BT even without taking into account the repeater and network adapters. For half-duplex transmission, the maximum values \u200b\u200bof the fiber optic cable segments should always be less than 100 m. The premises of 220 and 500 m are calculated for the worst case of the bandwidth of the multimode cable, which is from 160 to 500 MHz / km. Real cables usually have significantly better characteristics located between 600 and 1000 MHz / km. In this case, you can increase the length of the cable to about 800 m.

Single mode cable

For the L000Base-LX specification, a semiconductor laser with a wavelength of 1300 nm is always used as a radiation source.

The main area of \u200b\u200bapplication of the L000Base-LX standard is a single-mode fiber. The maximum cable length for single-mode fiber is 5000 m.

The L000Base-LX specification can work on a multimode cable. In this case, the limit distance is small - 550 m. This is due to the peculiarities of the propagation of coherent light in a wide channel of the multimode cable. To attach a laser transceiver to a multimode cable, you must use a special adapter. .

2. Creating a project of a computational local network

When creating a local computing network, it is assumed that:

1. Each class traffic is isolated from others.

2. There are three computer classes in the first: five computers; In the second - eleven computers; In the third - three computers.

3. Distance remoteness is: 1-87 meters; 2-74 meters; 3-74 meters.

4. The network is a peer with a speed of 100 MB / s, without accessing the Internet.

The cost of project implementation

table 2

Costs for the purchase of network equipment

Equipment	Specifications	amount

Network Card	COM-3CSOHO100TX Office Connect Fast Ethernet PCI 10 \\ 100 Base-TX
Switch	COM-3C16471 SS 3 Baseline 2024 24 * 10 \\ 100TX
Connector
Antivirus
Operating system

Table 3.

Configuration of Computers Working Group


Computer type	Work station
Motherboard	FM2 AMD A75 MSI FM2-A75MA-P33
CPU	AMD Athlon II x2 250

Video adapter	Built into mp
Network Card	10/100/1 1000Mbps PCI Adapter, 32 Bit, Wol, Jumbo, Retail
Power Supply	430 Watt ATX POWER SUPPLY
HDD	HDD Seagate 80GB. , 7200RPM, SATA-II, 8MB Cache
	Inwin C602 Black / Silver Middle ATX 430W (20 + 4pin, 12cm FAN)
Keyboard	SVEN 330, Silver
	A4-TECH MOP-59, Red Optical, Mini, USB + PS / 2, Roll
TOTAL: 18550 * 19 \u003d 352450

The total cost of the LAN project without taking into account the costs of fixing work was 548777 rubles.

Conclusion

In the course of the course work, practical and theoretical skills designing a computational local network was obtained. During the course of the course work, a local network of computer classrooms has been created.

The recommendations of the manufacturers of telecommunications equipment, the basics of standards were investigated, the requirements for the system being created and, as a result, a draft local computing network (LAN) of the conditional enterprise was developed.

The course paper presents the necessary calculations, drawings and schemes, the specification of the equipment and the materials necessary for the construction of the LAN.

The cost of equipment and software for the network in total amounted to 196327 rubles, and the cost of computer hardware was 3,52450 rubles.

List of sources and literature

1. V.G. Olifer. ON THE. Olifer Computer Networks, Principles, Technologies, Protocols 4th Edition 2010. - Chapter 2 pp. 55.3 p. 103.5 p. 139.

2. Peskov S.A., Kuzin A.V., Volkov A.N. Networks and telecommunications (3rd ed.) 2008 p. 232

4. Internet - resource lulu.ts6.ru. Access mode http.// 1.20.htm

5. Tannbaum E., Weseroll D. Computer Networks. 5th edition 2012

6. Tannbaum E. Computer networks. Principles, technologies, protocols. / E. Tonanbaum. - SPb.: Peter, 2007.

7. Maksimov N.V. Computer Networks: Tutorial [Text] / N.V. Maksimov, I.I. Popov - M.: Forum: Infra-M, 2005. - p. 109-111

8. Computer networks. Training course [Text] / Microsoft Corporation. Per. with ang. - M.: "Russian edition" Channel Trading Ltd. Ltd., 1998. -st. 258.

9. Craig Sun Computer Networks BHV-Petersburg, 2001 p. 7, 253, 234

10. Katie Iavens Computer Networks Peter 2006 p. 29.

11. www.ieeer8.org.

Posted on Allbest.ru.

3.1. Topology LAN enterprises

For the LAN enterprise under consideration of the most optimal topology, the topology of the star type due to the fact that it represents a more productive structure: each computer, including the server, is connected by a separate cable segment with a central concentrator (HUB).

The main advantage of such a network is its resistance to the CBM, arising from problems on individual PCs or due to damage to the network cable.

The most important information exchange characteristic in local sections are the so-called access methods (Access Methods), the regulatory procedure in which the workstation receives access to network resources and can exchange data.

Since the CSMA / CD method has proven itself precisely in male and secondary networks, for the enterprise under consideration, this method is convenient. In addition, the Ethernet network architecture, which will be used by the network of the enterprise, uses this method of access.

The network based on a twisted pair, in contrast to the network on the basis of a thin and tol-stoic coaxial cable, is built along the topology of the star. To post-relocate the network on the specified topology, a larger number of Cabab is required (but the price of twisted pair is small). A similar scheme has an invaluable advantage - high fault tolerance. The failure of one or several workstations does not lead to the failure of the entire system. True, if a hub will be released (HUB), his failure will affect all the devices under it.

Another advantage of this option is the simplicity of network expansion, since when using additional concentrations (up to four sequentially), it is possible to connect a large number of workstations (up to 1024). When applying a unshielded twisted pair (UTP), the length of the segment between the concentrator and the workstation should not exceed 100 m. This condition for the enterprise under consideration is performed.

3.2. Network resources

The next important aspect of the design of the network is the SMOP use of network resources (printers, faxes, modems and other peripherals).

The listed resources can be used both in peer-to-peer networks and networks with a dedicated server. However, in the case of a one-alone network, its disadvantages immediately revealed. To work with listed components, they need to be installed on the workstation or connect peripheral devices to it. When this mill is disconnected, all components and relevant services become unavailable for collective use.

In networks with a dedicated server, there is a round-the-clock dosted workstations to network peripherals, since the server never turns off if not counting short stops for technical convention.

There are four printer at the enterprise - in each department one by one. Consider the issue of connecting the printer to the LAN. For this, there are several ways:

connect to the workstation. The printer connects to that slave station, which is closest to it. As a result, this workstation becomes a print server. The lack of such a connection is that when performing tasks for printing, the performance of the workstation is reduced for some time, which is negatively scales on the operation of application programs with the intensive use of the printer. In addition, if the machine is turned off, the print server will become inaccessible to other nodes;
direct connection to the server. The printer connects to the parallel port of the server using a special cable. In this case, it is constantly available for all workstations. The disadvantage of this re-suction is due to a restriction on the length of the printer cable, providing correct data transmission. Although the cable can be stretched 10 m or more, it should be laid in boxes or overlap, which increases the cost of organizing the network;
connecting to the network via a special network interface. The printer is equipped with a network interface and connects to the network as a workstation. The interface card works as a network adapter, and the printer is registered on the server as a LAN node. Serve-faith software transmits print jobs on the network directly to the connected network printer;
connecting to a selected print server. An alternative to the previous option is to use specialized print servers. Such a server is a network interface, an arranged in a separate case, with one or more connectors (pores) for connecting printers. However, in this case, the use of the print server is impractical.

In this example, due to the fact that the installation of a separate print server increases the cost of creating a network (as well as the purchase of a printer with a network interface), it is advisable to connect printers directly to workstations in the departments. In favor of the Tax decision, the printers are located in those rooms where the need for them is the greatest. Therefore, the first method of connecting the printer was selected.

4. Development and description of LAN enterprises

4.1. Construction scheme

The LAN is built on the topology star, although, if more precisely, it is a tree: all network customers are branches of the central "main" channel. But the topologically, the entire network represents a star with the center in the form of a hub in the server room of the information and technical support department.

4.2. Basic administrative blocks

Combining computers in working groups gives two important pre-property to network administrators and users. The first, most significant, is that the domain servers make up (form) a single administrative unit, sharing the security service and information of user accounting cards. Each working group has one database containing accounting of user cards and groups, as well as the installation parameters of the security system.

The second advantage applies to the convenience of users: when users browsing the network in search of available resources, they see domains, and servers and printers not scattered throughout the network.

4.3. Configuring Server

The network operating system is performed on the server. On the other hand-line, customer computers can work under the control of various operating systems. In order for the customer's operating system to use the network, special drivers must be installed, which allow the computer-client-client network interface board to communicate with the network. These drivers work like printer drivers that allow applications to send information to Prime. Network Driver software allows programs to send and receive information over the network. Each computers on the network may contain one or more network interface cards that connect the computer with the network.

Obviously, the performance of the LAN depends on the computer that is used as a server. When using Windows 2000 Server, you must navigate the most high-speed computers. There is a choice between the ready-made servers offered by manufacturers and suppliers of computer equipment and self-assembly servers. In the presence of a certain experience, the server independently collected by the order can be alter-native to the finished product. Therefore, attention should be paid to a number of issues discussed below.

On the question of the bus used, the answer is unequivocal - PCI. In addition to the fact that the PCI components have high performance (due to the 64-bit busbar), they still allow software con-appear. Thanks to the last circumstance, possible confa-lyters between the plug-in hardware resources are almost always preferable.

Windows 2030 Server initially places high requirements for the operational memory. Therefore, taking into account the fact that the cost of opaire-memory today is not so large, the minimum volume of RAM is not advisable to do less than 512 MB (both from the point of view of the price and in terms of performance).

On servers it is recommended to use Fast SCSI hard drives and a SCSI corresponding adapter. When using Fast SCSI, the transfer rate of data reaches 10 Mbps. The newest hard drives with the Ultra SCSI interface have a transmission rate up to 20 Mbps. If the Wine Chester should still work faster, it is necessary to install a more doubtful Ultra Wide SCSI and the corresponding controller. The data transfer rate at the Ultra Wide SCSI disk reaches 40 Mbps, and it is an ideal device for a high-performance server, including for networks with intensive data exchange. OD-NAO for the enterprise under consideration is better to use OTE channel-wide hard drives, since the use of SCSI significantly increases the server cost.

A small body for such a computer is contraindicated, as this can lead to overheating, especially when using a high-productive processor and several hard drives. The perfect body will be a Big Tower type case, among other things, ensuring the possibility of further expansion of the system. Even more, special cases for servers equipped with powerful power supplies, additional fans, removable plugs and protective front panel. If the server is equipped with two or more hard drives, it is necessary to think about it with additional oxide. To do this, use special fans that can be additionally installed in the system unit.

Since all workstations connected to the network will constantly access the server, one of its most important components is a productive 32-bit network card. It should effectively help the information exchange, i.e. To have a coprocessor, accepting the basic functions of the central processor for processing entering the data server.

Thus, the LAN topology has been developed for a small pre-reception, justified the use of a specific OS server.

An example of approach to the development of the LAN enterprise. Part 2 | 2011-11-24 04:05:14 | Super User | Local network | https: //sight/media/system/images/new.png. | In the final part of the article, consider the main stages of building a local computer network of the enterprise, we will get acquainted with the concept of the topology of computer networks | Topology network, topology of local networks, computer network topology, network resources, use of network resources