Introduction

Modern society has entered the post-industrial era, which is characterized by the fact that information has become the most important resource for the development of the economy and society. In line with the general development of high technologies, the main contribution to the informatization of all spheres of life is made by computer technologies.

One of the characteristic features of the current stage of development of information technology can be defined by the words "unification" or "integration". Analog and digital, telephone and computer are combined, speech, data, audio and video signals are combined in one stream, technique and art (multimedia and hypermedia) are combined into a single technology. The flip side of this process is “sharing” or “sharing”. An integral part of this process is the development of computer networks.

Computer networks are essentially distributed systems. The main feature of such systems is the presence of multiple data centers. Computer networks, also called computing networks, or data transmission networks, are the logical result of the evolution of two most important scientific and technical branches of modern civilization - computer and telecommunication technologies. On the one hand, networks are a special case of distributed computing systems in which a group of computers consistently performs a group of interrelated tasks, exchanging data in an automatic mode. On the other hand, computers and data multiplexing have evolved in various telecommunication systems.

A local area network (LAN) or LAN is a group of personal computers or peripheral devices interconnected by a high-speed data link in the location of one or many nearby buildings. The main task that is posed in the construction of local computer networks is the creation of a telecommunications infrastructure of the company, which ensures the solution of the tasks set with the greatest efficiency. There are a number of reasons for combining individual personal computers on a LAN:

First, resource sharing allows multiple PCs or other devices to share a single disk (file server), DVD-ROM drive, printers, plotters, scanners, and other equipment, thereby lowering the cost per user.

Secondly, in addition to sharing expensive peripheral devices, LVL allows similar use of network versions of application software.

Thirdly, the LAN provides new forms of user interaction in one team, for example, working on a common project.

Fourthly, LANs make it possible to use common means of communication between different application systems (communication services, data and video data transmission, speech, etc.).

There are three principles of LAN:

1) Openness, the ability to connect additional computers and other devices, as well as communication lines (channels) without changing the hardware and software of existing network components.

2) Flexibility - preservation of performance when the structure changes as a result of failure of any computer or communication line.

3) Efficiency ensuring the required quality of service for users at minimal cost.

A local area network has the following distinctive features:

High data transfer speed (up to 10 GB), high bandwidth;

Low transmission errors (high quality transmission channels);

Effective high-speed data exchange control mechanism;

The exact number of computers connected to the network. At present, it is difficult to imagine any organization without a local network installed in it, all organizations are striving to modernize their work with the help of local networks.

This course project describes the creation of a local network based on Gigabit Ethernet technology, by connecting several houses, and the organization of Internet access.

1. Creation of a local area network

1.1 Network topologies

Topology is a way of physically connecting computers to a local area network.

There are three main topologies used in the construction of computer networks:

Bus topology;

Star topology;

Ring topology.

When creating a network with the "Bus" topology, all computers are connected to one cable (Figure 1.1). Terminators should be located at its ends. This topology is used to build 10 Megabit 10Base-2 and 10Base-5 networks. Coaxial cables are used as the cable.

Figure 1.1 - Topology "Bus"

Passive topology is based on the use of one common communication channel and its collective use in a time-sharing mode. Violation of a common cable or any of the two terminators leads to the failure of the network section between these terminators (network segment). Disconnecting any of the connected devices has no effect on the operation of the network. Failure of the communication channel destroys the entire network. All computers on the network "listen" to the carrier and do not participate in the transfer of data between neighbors. The throughput of such a network decreases with increasing load or with an increase in the number of nodes. Active devices - repeaters with an external power supply can be used to connect pieces of the bus.

The "Star" topology involves connecting each computer with a separate wire to a separate port of a device called a hub or repeater (repeater), or a hub (Hub) (Figure 1.2).

Figure 1.2 - "Star" topology

Hubs can be either active or passive. If there is a disconnection between the device and the hub, the rest of the network continues to function. True, if this device was the only server, then the work will be somewhat difficult. If the hub fails, the network will stop working.

This network topology is most useful when looking for damage to network elements: cables, network adapters or connectors. When adding new devices, the star is also more convenient than the common bus topology. You can also take into account that 100 and 1000 Mbit networks are built according to the "Star" topology.

Ring topology is an active topology. All computers on the network are connected in a vicious circle (Figure 1.3). Routing cables between workstations can be difficult and costly if they are not in a ring but, for example, in a line. Twisted pair or fiber optic is used as a carrier in the network. Messages circulate in a circle. A workstation can transfer information to another workstation only after it receives the right to transfer (token), so collisions are excluded. Information is transmitted around the ring from one workstation to another, therefore, if one computer fails, if no special measures are taken, the entire network will fail.

The transmission time of messages increases in proportion to the increase in the number of nodes in the network. There are no restrictions on the diameter of the ring, because it is determined only by the distance between nodes in the network.

In addition to the above network topologies, the so-called. hybrid topologies: star-bus, star-ring, star-star.

Figure 1.3 - Topology "Ring"

In addition to the three considered basic, basic topologies, the network topology "tree" is often used, which can be considered as a combination of several stars. As with a star, a tree can be active, or true, and passive. With an active tree, central computers are located in the centers of combining several communication lines, and with a passive tree, hubs.

Combined topologies are also used quite often, among which the most widespread are star-bus and star-ring. A star-bus topology uses a combination of a bus and a passive star. In this case, both individual computers and entire bus segments are connected to the hub, that is, the physical bus topology is actually implemented, including all computers on the network. In this topology, several hubs can also be used, interconnected and forming a so-called backbone bus. In this case, separate computers or bus segments are connected to each of the hubs. Thus, the user can flexibly combine the advantages of bus and star topologies, as well as easily change the number of computers connected to the network.

In the case of a star-ring topology, not the computers themselves are united into a ring, but special hubs, to which computers in turn are connected using star-shaped double communication lines. In reality, all computers on the network are included in a closed loop, since all communication lines inside the hubs form a closed loop. This topology allows you to combine the benefits of star and ring topologies. For example, hubs allow you to collect all the cable connection points in a network in one place.

This course project will use a star topology, which has the following advantages:

1. failure of one workstation does not affect the operation of the entire network as a whole;

2. good scalability of the network;

3. easy troubleshooting and network breaks;

4. high network performance (subject to correct design);

5. flexible administration options.

1.2 Cable system

The choice of cabling is dictated by the type of network and the selected topology. The physical characteristics of the cable required by the standard are laid down during its manufacture, as evidenced by the markings applied to the cable. As a result, today almost all networks are designed on the basis of UTP and fiber-optic cables, coaxial cable is used only in exceptional cases, and then, as a rule, when organizing low-speed stacks in wiring closets.

Today, only three types of cables are laid in projects of local computer networks (standard):

coaxial (two types):

Thin coaxial cable

Thick coaxial cable

twisted pair (two main types):

Unshielded twisted pair (UTP);

Shielded twisted pair (STP).

fiber optic cable (two types):

Multimode cable (fiber optic cable multimode);

Single mode cable (fiber optic cable single mode).

Not long ago, coaxial cable was the most common type of cable. This is due to two reasons: first, it was relatively inexpensive, lightweight, flexible and easy to use; second, the widespread popularity of coaxial cable has made it safe and easy to install.

The simplest coaxial cable consists of a copper core, insulation surrounding it, a braided metal shield and an outer jacket.

If the cable, in addition to the metal braid, has a layer of "foil", it is called a double-screened cable (Figure 1.4). In the presence of strong interference, you can use a cable with a quadruple shielding, it consists of a double layer of foil and a double layer of metal braiding.

Figure 1.4 - Coaxial cable structure

The braid, called the shield, protects the data transmitted over the cables by absorbing external electromagnetic signals called interference or noise, so the shield does not allow interference to distort the data.

Electrical signals are transmitted through the conductor. A core is a single wire or bundle of wires. The core is usually made of copper. The conductor and the metal braid must not touch, otherwise a short circuit will occur and noise will distort the data.

Coaxial cable is more noise-resistant, signal attenuation in it is less than in twisted pair.

Attenuation is the decrease in signal strength as it travels through the cable.

Thin coaxial cable is a flexible cable with a diameter of about 5 mm. It is applicable to almost any type of network. Connects directly to the network adapter card using a T-connector.

The connectors on the cable are called BNC connectors. The thin coaxial cable is capable of transmitting the signal at a distance of 185 m, without its delayed attenuation.

Thin coaxial cable belongs to a group called the RG-58 family. The main distinguishing feature of this family is the copper core.

RG 58 / U - solid copper conductor.

RG 58 / U - twisted wires.

RG 58 C / U - military standard.

RG 59 - Used for broadband transmission.

RG 62 - Used in Archet networks.

A thick coaxial cable is a relatively rigid cable with a diameter of about 1 cm. It is sometimes called the Ethernet standard because this type of cable was designed for a given network architecture. The copper core of this cable is thicker than that of a thin cable, so it carries signals further. A special transceiver device is used to connect to a thick cable.

The transceiver is equipped with a special connector called a "vampire tooth" or piercing coupler. It penetrates the insulating layer and comes into contact with the conductive core. To connect the transceiver to the network adapter, connect the transceiver cable to the AUI port connector on the network card.

A twisted pair is two insulating copper wires twisted around each other. There are two types of thin cable: unshielded twisted pair (UTP) and shielded twisted pair (STP) (Figure 1.5).

Figure 1.5 - Unshielded and shielded twisted pair

Several twisted pairs are often enclosed in a single protective sheath. Their number in such a cable may be different. Curling wires allows you to get rid of electrical noise induced by neighboring pairs and other sources (motors, transformers).

Unshielded twisted pair (10 Base T specification) is widely used in LAN, the maximum segment length is 100m.

The unshielded twisted pair consists of 2 insulated copper wires. There are several specifications that regulate the number of turns per unit of length, depending on the purpose of the cable.

1) Traditional telephone cable, which can only transmit speech.

2) A cable capable of transmitting data at speeds up to 4 Mbps. Consists of 4 twisted pairs.

3) A cable capable of transmitting data at speeds up to 10 Mbps. Consists of 4 twisted pairs with 9 turns per meter.

4) A cable capable of transmitting data at speeds up to 16 Mbps. Consists of 4 twisted pairs.

5) A cable capable of transmitting data at speeds up to 100 Mbps. Consists of 4 twisted copper wire pairs.

One potential problem with all types of cables is crosstalk.

Crosstalk is crosstalk caused by signals on adjacent wires. Unshielded twisted pair cables are particularly affected by this interference. To reduce their influence, a screen is used.

Shielded twisted pair (STP) cable has a copper braid that provides greater protection than unshielded twisted pair cable. Pairs of STP wires are wrapped in foil. As a result, the shielded twisted pair has excellent isolation, protecting the transmitted data from external interference.

Consequently, STP is less susceptible to electrical interference than UTP and can transmit signals at higher speeds and over long distances.

To connect a twisted pair to a computer, telephone connectors RG-45 are used.

Figure 1.6 - Structure of fiber optic cable

In a fiber optic cable, digital data is propagated along optical fibers in the form of modulated light pulses. This is a relatively reliable (secure) method of transmission since no electrical signals are transmitted. Therefore, fiber optic cable cannot be hidden and data intercepted, from which any cable conducting electrical signals is not immune.

Fiber-optic lines are designed to move large amounts of data at very high speeds, since the signal in them is practically not attenuated or distorted.

An optical fiber is an extremely thin glass cylinder called a core, covered with a layer of glass called a cladding, with a different refractive index than the core (Figure 1.6). Sometimes fiber is made of plastic, it is easier to use, but has inferior performance compared to glass.

Each glass fiber transmits signals in only one direction, so the cable consists of two fibers with separate connectors. One of them is used for signal transmission, the other for reception.

Transmission over fiber optic cable is not subject to electrical interference and is carried out at an extremely high speed (currently up to 100 Mbit / s, theoretically possible speed - 200000 Mbit / s). It can transmit data over many kilometers.

This course project will use Category 5E Twisted Pair and Fiber Optic Cable.

1.3 Gigabit Ethernet Network Technology

When organizing the interaction of nodes in local networks, the main role is assigned to the link layer protocol. However, in order for the data link layer to cope with this task, the structure of local networks must be quite definite, for example, the most popular data link layer protocol - Ethernet - is designed for parallel connection of all network nodes to a common bus for them - a piece of coaxial cable. This approach, which consisted of using simple structures of cable connections between computers on a local area network, corresponded to the main goal set by the developers of the first local area networks in the second half of the 70s. This goal was to find a simple and cheap solution for connecting several dozen computers located within the same building into a computer network.

This technology has lost its practicality, since now not dozens, but hundreds of computers located not only in different buildings, but also in different areas, are connected to local networks. Therefore, we choose a higher speed and reliability of information transmission. These requirements are met by Gigabit Ethernet 1000Base-T technology.

Gigabit Ethernet 1000Base-T is based on twisted pair and fiber optic cable. Since Gigabit Ethernet is compatible with 10 Mbps and 100Mbps Ethernet, it is easy to migrate to this technology without investing heavily in software, cabling, and training.

Gigabit Ethernet is an extension of IEEE 802.3 Ethernet that uses the same packet structure, format and support for CSMA / CD, full duplex, flow control, and more, while delivering a theoretical 10x performance improvement.

CSMA / CD (Carrier-Sense Multiple Access with Collision Detection) is a technology for multiple access to a common transmission medium in a local computer network with collision control. CSMA / CD refers to decentralized random methods. It is used both in conventional networks such as Ethernet and in high-speed networks (Fast Ethernet, Gigabit Ethernet).

Also called the network protocol, which uses the CSMA / CD scheme. The CSMA / CD protocol operates at the data link layer in the OSI model.

The characteristics and areas of application of these popular in practice networks are related precisely to the peculiarities of the access method used. CSMA / CD is a modification of the "pure" Carrier Sense Multiple Access (CSMA).

If, while transmitting a frame, the workstation detects another signal occupying the transmission medium, it stops transmission, sends a jam signal, and waits for a random amount of time (known as a "backoff delay" and found with the truncared binary exponential backoff algorithm) before send the frame again.

Collision detection is used to improve CSMA performance by interrupting transmission immediately after collision detection and reducing the likelihood of a second collision during retransmission.

Collision detection methods depend on the equipment used, but on electrical buses such as Ethernet, collisions can be detected by comparing transmitted and received information. If it differs, then another transmission is superimposed on the current one (a collision has occurred) and the transmission is interrupted immediately. A jam signal is sent, which delays the transmission of all transmitters for an arbitrary time interval, reducing the likelihood of collisions during retry.

1.4 Hardware

The choice of hardware should be given special attention, the possibility of expanding the system and the ease of its modernization play a significant role, since this is what allows to provide the required performance not only at the current time, but also in the future.

Of greatest interest is the maximum amount of RAM that can be used on this server, the possibility of installing a more powerful processor, as well as a second processor (if you plan to use an operating system that supports a dual-processor configuration). The question of what configuration of the disk subsystem can be used on this server is also important, first of all, what is the volume of disks, the maximum number of them.

There is no doubt that a vital parameter of any server is its high-quality and uninterrupted power supply. In this regard, it is necessary to check that the server has several (at least two) power supplies. Usually these two power supplies work in parallel, i.e. if it fails, the server continues to work, receiving power from another (serviceable) power supply. In this case, there should also be the possibility of their "hot" replacement. And, needless to say, an uninterruptible power supply is needed. Its presence allows, in the event of a power outage, at least to correctly shut down the operating system and turn on the server.

High reliability of servers is achieved by implementing a set of measures related to both ensuring the necessary heat exchange in the case, controlling the temperature of the most important components, monitoring a number of other parameters, and fully or partially duplicating subsystems.

It is also necessary to pay attention to the selection of additional hardware components of the network. When choosing network equipment, it is worth considering the network topology and the cabling system on which it is executed.

· The level of equipment standardization and its compatibility with the most common software tools;

· Speed ​​of information transfer and the possibility of its further increase;

· Possible network topologies and their combinations (bus, passive star, passive tree);

· Method of control of exchange in the network (CSMA / CD, full duplex or marker method);

· Permitted types of network cable, its maximum length, immunity from interference;

· Cost and technical characteristics of specific hardware (network adapters, transceivers, repeaters, hubs, switches).

Minimum server requirements:

CPU AMD Athlon64 X2 6000+ 3.1GHz;

Dual NC37H network adapters with TCP / IP Offload Engine network card;

RAM 8 GB;

HDD 2x500 GB Seagate Barracuda 7200 rpm.

1.5 Software

Computer networks software consists of three components:

1) stand-alone operating systems (OS) installed on workstations;

2) network operating systems installed on dedicated servers, which are the basis of any computer network;

3) network applications or network services.

As a stand-alone operating system for workstations, as a rule, modern 32-bit operating systems are used - Windows 95/98, Windows 2000, Windows XP, Windows VISTA.

The following are used as network operating systems in computer networks:

NetWare OS from Novell;

Microsoft network operating systems (Windows NT, Microsoft Windows 2000 Server, Windows Server 2003, Windows Server 2008)

Windows Server 2008 provides three main benefits:

1) Improved control

Windows Server 2008 allows you to better control your server and network infrastructure and focus on solving your top priority tasks by:

Simplified IT infrastructure management with new tools that provide a single interface for configuring and monitoring servers and the ability to automate routine operations.

Streamline and manage Windows Server 2008 installation and management by deploying only the roles and features you need. Configuring servers reduces vulnerabilities and reduces the need for software updates, resulting in easier ongoing maintenance.

Find and troubleshoot efficiently with powerful diagnostics that provide a visual insight into the current state of your server environment, both physical and virtual.

Better control over remote servers such as branch servers. By streamlining server administration and data replication, you can better serve your users and eliminate some of the management headaches.

Easily manage your web servers with Internet Information Services 7.0, a powerful web platform for applications and services. This modular platform has a simpler task-based management interface and integrated state management for Web services, provides tight control over site interactions, and includes a number of security enhancements.

Improved control of user settings with Advanced Group Policy.

2) Increased flexibility

The following features in Windows Server 2008 enable you to create flexible and dynamic datacenters that meet your ever-changing business needs.

Embedded technologies for virtualization on one server of several operating systems (Windows, Linux, etc.). With these technologies and simpler, more flexible licensing policies, you can now easily take advantage of the benefits of virtualization, including the economics.

Centralized application access and seamless integration of remotely published applications. In addition, it should be noted the ability to connect to remote applications through a firewall without using a VPN - this allows you to quickly respond to the needs of users, regardless of their location.

A wide range of new deployment options.

Flexible and functional applications connect workers to each other and to data, thus enabling visibility, sharing and processing of information.

Interaction with the existing environment.

A developed and active community for support throughout the life cycle.

3) Improved protection

Windows Server 2008 strengthens the security of the operating system and the environment as a whole, creating a solid foundation on which you can grow your business. Windows Server protects servers, networks, data, and user accounts from failure and intrusion through the following.

Enhanced security features reduce the vulnerability of the server core, thereby increasing the reliability and security of the server environment.

Network access protection technology can isolate computers that do not meet the requirements of current security policies. The ability to enforce security compliance is a powerful means of protecting your network.

Enhanced intelligent rule and policy writing solutions that improve the manageability and security of network functionality enable the creation of policy-driven networks.

Data protection that allows access only to users with the proper security context and prevents loss in the event of a hardware failure.

Anti-malware protection with User Account Control with a new authentication architecture.

Increased system resilience, reducing the likelihood of loss of access, work results, time, data and control.

For users of local area networks, a set of network services is of great interest, with the help of which he gets the opportunity to view a list of computers on the network, read a remote file, print a document on a printer installed on another computer on the network, or send a mail message.

The implementation of network services is carried out by software (software tools). The file and print services are provided by the operating systems, while the rest of the services are provided by the network application or applications. Traditional network services include: Telnet, FTP, HTTP, SMTP, POP-3.

Telnet service allows you to organize user connections to the server using the Telnet protocol.

The FTP service provides file transfers from Web servers. This service is provided by Web browsers (Internet Explorer, Mozilla Firefox, Opera, etc.)

HTTP is a service designed to view Web pages (Web sites), provided by network applications: Internet Explorer, Mozilla Firefox, Opera, etc.

SMTP, POP-3 - incoming and outgoing e-mail services. They are implemented by mail applications: Outlook Express, The Bat, etc.

An antivirus program is also required on the server. ESET NOD32 Smart Security Business Edition is a new integrated solution that provides comprehensive server and workstation protection for all types of organizations.

This solution includes antispam and personal firewall functions that can be used directly on the workstation.

ESET NOD32 Smart Security Business Edition provides support and protection for Windows, Novell Netware and Linux / FreeBSD file servers against known and unknown viruses, worms, Trojans, spyware, and other Internet threats. The solution includes on-access scanning, on-demand scanning and automatic updates.

ESET NOD32 Smart Security Business Edition includes ESET Remote Administrator, which provides updates and centralized administration in corporate or WAN environments. The solution provides optimal performance for systems and networks while reducing bandwidth consumption. The solution has the functionality and flexibility that any company needs:

1) Installation on the server. The version for corporate clients ESET NOD32 Smart Security can be installed both on the server and on workstations. This is especially important for companies seeking to maintain their competitiveness, as servers are as vulnerable to attacks as normal workstations. If the servers are not protected, a single virus can damage the entire system.

2) Remote administration. With ESET Remote Administrator, you can monitor and administer your security software solution from anywhere in the world. This factor is of particular importance for geographically distributed companies, as well as for system administrators who prefer to work remotely or are on the move.

Possibility of "Mirror". The ESET NOD32 Mirror feature allows the IT administrator to limit network bandwidth by creating an internal update server. As a result, ordinary users do not need to go online to receive updates, which not only saves resources, but also reduces the overall vulnerability of the information structure.

1.6 Brief network plan

Table 1.1 - Brief equipment summary

2 Physical construction of a local network and organization of Internet access

2.1 Network equipment

2.1.1 Active equipment

In this course project, the following equipment will be used:

D-link DGS-3200-16 switch;

D-link DGS-3100-24 switch;

D-link DFL-1600 router;

Converter 1000 Mbit / s D-Link DMC-810SC;

Server IBM System x3400 M2 7837PBQ.

Figure 2.1 - D-link DGS-3200-16 switch

General characteristics

Device type switch

there is

Number of slots for additional

interfaces 2

Control

Console port there is

Web interface there is

Telnet support there is

SNMP support there is

Additionally

IPv6 support there is

Standards support Auto MDI / MDIX, Jumbo Frame, IEEE 802.1p (Priority tags), IEEE 802.1q (VLAN), IEEE 802.1d (Spanning Tree), IEEE 802.1s (Multiple Spanning Tree)

Dimensions (WxHxD) 280 x 43 x 180 mm

Number of ports 16 x Ethernet 10/100/1000

switch Mbps

32 Gbps

MAC address table size 8192

Router

IGMP v1

Figure 2.2 - D-link DGS-3100-24 switch

General characteristics

Device type switch

Rack mountable there is

Number of slots for additional interfaces 4

Control

Console port there is

Web interface there is

Telnet support there is

SNMP support there is

Additionally

Standards support Auto MDI / MDIX, Jumbo Frame, IEEE 802.1p (Priority tags), IEEE 802.1q (VLAN), IEEE 802.1d (Spanning Tree), IEEE 802.1s (Multiple Spanning Tree)

Dimensions (WxHxD) 440 x 44 x 210 mm

Weight 3.04 kg

Additional Information 4 combo 1000BASE-T / SFP ports

Number of ports 24 x Ethernet 10/100/1000

switch Mbps

Stack support there is

Internal bandwidth 68 Gbps

MAC address table size 8192

Router

Dynamic routing protocols IGMP v1

Figure 2.3 - D-link DFL-1600 router

General characteristics

Device type router

Control

Console port there is

Web interface there is

Telnet support there is

SNMP support there is

Additionally

Standards support IEEE 802.1q (VLAN)

Dimensions (WxHxD) 440 x 44 x 254 mm

Additional Information 6 user configurable Gigabit Ethernet ports

Number of ports 5 x Ethernet 10/100/1000

switch Mbps

Router

Firewall there is

NAT there is

DHCP server there is

Dynamic protocols

routing IGMP v1, IGMP v2, IGMP v3, OSPF

VPN Tunnel Support yes (1200 tunnels)

Figure 2.4 - Converter 1000 Mbit / s D-Link DMC-805G

General characteristics

· One channel of media conversion between 1000BASE-T and 1000BASE-SX / LX (SFP mini GBIC transceiver);

· Compatible with IEEE 802.3ab 1000BASE-T, IEEE802.3z 1000BASE-SX / LX Gigabit Ethernet standards;

· Status indicators on the front panel;

LLCF support (Link Loss Carry Forward, Link Pass Through);

· Supports duplex and auto-negotiation for optical port;

DIP switch for setting Fiber (auto / manual), LLR (Enable / Disable);

· Support LLR (Link Loss Return) for FX port;

· Use as a stand-alone device or installation in the DMC-1000 chassis;

· Monitoring duplex / channel status for both types of environments through the DMC-1002 control module when installed in the DMC-1000 chassis;

· Forced setting of duplex mode, LLR on / off for FX, ports on / off through the DMC-1002 control module of the DMC-1000 chassis;

· Data transmission at channel speed;

· Hot swap when installed in the chassis;

Dimensions (edit) 120 x 88 x 25 mm

Weight 305 BC

Working temperature 0 ° to 40 ° C

Storage temperature -25 ° to 75 ° C

Humidity 10% to 95% non-condensing

Figure 2.5 - Server IBM System x3400 M2 7837PBQ

Server characteristics

CPU Intel Xeon Quad-Core

Series E5520

Processor frequency but 2260 MHz

Number of processors 1 (+1 optional)

System bus frequency 1066 MHz

Second level cache (L2C) 8 Mb

Chipset Intel 5500

RAM size 12 Gb

Maximum RAM 96 Gb

RAM slots 12

RAM type DDR3

Chipset video Built in

Video memory size 146 Mb

Number of hard drives 3

Hard disk size 0 Gb

Maximum number of disks 8

Hard disk controller M5015

Optical drives DVD ± RW

Network interface 2x Gigabit Ethernet

External I / O ports 8хUSB ports (six external, two internal), dual-port

Mounting type Tower

Power supply type 920 (x2) W

Maximum amount

power supplies 2

Dimensions (edit) 100 x 580 x 380 mm

Weight 33 kg

Guarantee 3 years

Additional Information Keyboard + Mouse

Additional accessories (ordered separately) Servers IBM System x3400 M2 7837PBQ

2.1.2 Passive equipment

Passive equipment constitutes the physical infrastructure of networks (patch panels, sockets, racks, enclosures, cables, cable channels, trays, etc.). The bandwidth and quality of communication channels largely depend on the quality of the cable system, therefore, complex and expensive equipment under the control of qualified personnel in this area should be used to test physical data carriers.

2.2 Calculation of the cable system

2.2.1 Calculation of the length of the fiber optic cable of the main trunk

In the course project, you need to connect 4 houses. Because given floors are 5th, 12th and 14th, then it is more expedient to lead the main fiber-optic cable over air communications.

A special self-supporting fiber-optic cable is used to suspend the main highway between the poles and buildings, which has a central power element (CSE) and a steel cable. The optimum distance between the cable support supports is from 70 to 150 meters.

Figure 2.5 - Location of houses

Table 2.1 - Calculation of the length of the fiber-optic cable of the main trunk

Cable section	Length, m	Number of segments	Length with a margin, m
1-2	105	1	136,5
2-3	75	1	97,5
3-4	190	1	247
4-5	100	1	130
5-6	75	1	97,5
Total			708,5

2.2.2 Calculation of Twisted Pair Length

Cable risers are used to lay the cable through the floors. In the entrances. In entrances, the cable can be left unpacked, because the entrances are not so dirty and the threats of a sharp temperature drop and pollution are minimal.

The twisted pair from the switch on the roof to the desired floor goes along the riser without any protection, from the electrical panel to the apartment, both in cable ducts and without them, simply attached to the wall with brackets.

The server and the router are located in house No. 2 on the 5th floor of the 3rd entrance in a sealed room with a constant temperature maintenance of no more than 30 ° C.

Table 2.2 - Calculation of the length of the twisted pair in houses

	Distance from switch to hole in							Number of cables per apartment, m				Length-on with a reserve, m
2	52	55	58	63	56	51	48	15	4	7	1952	2537,6
5	34	30	38	28	26	-	-	15	4	5	924	1201,2
7	42	45	48	53	46	41	38	15	4	7	1672	2173,6
8	34	30	38	28	26	-	-	15	5	5	1155	1501,5
											5703	7413,9

2.3 Logical network structuring

When the switch is operating, the data transmission medium of each logical segment remains common only for those computers that are directly connected to this segment. The switch connects the data transmission media of various logical segments. It transfers frames between logical segments only when necessary, that is, only when the communicating computers are in different segments.

Dividing a network into logical segments improves network performance if the network contains groups of computers that primarily communicate with each other. If there are no such groups, then the introduction of switches into the network can only degrade the overall performance of the network, since deciding whether to transfer a packet from one segment to another requires additional time.

However, even in a medium-sized network, such groups, as a rule, are available. Therefore, dividing it into logical segments gives a performance gain - traffic is localized within groups, and the load on their shared cabling systems is significantly reduced.

Switches make a decision on which port to send a frame to by analyzing the destination address placed in the frame, as well as based on information about the belonging of a computer to a particular segment connected to one of the switch ports, that is, based on information about the network configuration ... In order to collect and process information about the configuration of the segments connected to it, the switch must go through the "learning" stage, that is, do some preliminary work on its own to study the traffic passing through it. Determination of the belonging of computers to segments is possible due to the presence in the frame of not only the destination address, but also the address of the source that generated the packet. Using source address information, the switch maps port numbers to computer addresses. In the process of studying the network, the bridge / switch simply transmits the frames that appear at the inputs of its ports to all other ports, working as a repeater for some time. After the bridge / switch learns that the addresses belong to the segments, it starts transmitting frames between ports only in the case of inter-segment transmission. If, after training is complete, a frame with an unknown destination address suddenly appears at the switch input, then this frame will be repeated on all ports.

Bridges / switches that work in this way are usually called transparent, since the appearance of such bridges / switches in the network is completely invisible to its end nodes. This avoids changing their software when moving from simple hub-only configurations to more complex, segmented configurations.

There is another class of bridges / switches that transfer frames between segments based on complete information about the intersegment route. This information is written into the frame by the source station of the frame, therefore, such devices are said to implement the source routing algorithm. When using bridges / switches with source routing, end nodes must be aware of the division of the network into segments and network adapters, in which case they must have a component in their software that deals with the choice of the route of frames.

For the simplicity of the principle of operation of a transparent bridge / switch, you have to pay with restrictions on the topology of a network built using devices of this type - such networks cannot have closed routes - loops. The bridge / switch cannot function properly on a looped network, causing the network to become clogged with looping packets and degrading performance.

A Spanning Tree Algorithm (STA) has been developed to automatically recognize loops in a network configuration. This algorithm allows bridges / switches to adaptively build a link tree as they learn the link topology of segments using special test frames. When closed loops are detected, some links are declared redundant. The bridge / switch can only use the backup link if a primary link fails. As a result, networks built on the basis of bridges / switches supporting the spanning tree algorithm have a certain margin of safety, but it is impossible to improve performance by using multiple parallel links in such networks.

2.4 IP addressing on the network

There are 5 classes of IP addresses - A, B, C, D, E. The belonging of an IP address to a particular class is determined by the value of the first octet (W). The following shows the correspondence between the values ​​of the first octet and the address classes.

Table 2.3 - Range of octets of IP address classes

The IP addresses of the first three classes are designed to address individual nodes and individual networks. Such addresses consist of two parts - the network number and the node number. This scheme is similar to the postcode scheme - the first three digits code for the region, and the rest are the post office within the region.

The advantages of a two-tier scheme are obvious: it allows, firstly, to address entirely separate networks within a composite network, which is necessary to ensure routing, and secondly, to assign numbers to nodes within one network independently of other networks. Naturally, computers belonging to the same network must have IP addresses with the same network number.

IP addresses of different classes differ in the bit number of network and host numbers, which determines their possible range of values. The following table summarizes the main characteristics of Class A, B, and C IP addresses.

Table 2.4 - Characteristics of IP - addresses of classes A, B and C

For example, the IP address 213.128.193.154 is a class C address and belongs to host number 154 located on network 213.128.193.0.

The addressing scheme, defined by classes A, B, and C, allows data to be sent either to a single node or to all computers on a single network (broadcast). However, there is network software that needs to broadcast data to a specific group of nodes, not necessarily on the same network. In order for programs of this kind to function successfully, the addressing system must provide for the so-called group addresses. Class D IP addresses are used for these purposes. The Class E address range is reserved and is not currently used.

Along with the traditional decimal form of notation of IP addresses, the binary form can also be used, which directly reflects the way the address is represented in the computer memory. Since an IP address is 4 bytes long, it is represented in binary as a 32-bit binary number (that is, a sequence of 32 zeros and ones). For example, the address 213.128.193.154 in binary form is 11010101 1000000 11000001 10011010.

IP assumes the presence of addresses, which are treated in a special way. These include the following:

1) Addresses, the value of the first octet of which is 127. Packets sent to such an address are not actually transmitted to the network, but processed by the software of the sending node. Thus, a node can forward data to itself. This approach is very convenient for testing network software in conditions where there is no way to connect to the network.

2) Address 255.255.255.255. A packet whose destination is 255.255.255.255 should be sent to all nodes on the network where the source is located. This type of broadcast is called limited broadcast. In binary form, this address is 11111111 11111111 11111111 11111111.

3) Address 0.0.0.0. It is used for business purposes and is interpreted as the address of the node that generated the packet. Binary representation of this address 00000000 00000000 00000000 00000000

Additionally, addresses are interpreted in a special way:

The scheme for dividing an IP address into a network number and a node number, based on the concept of an address class, is rather rough, since it assumes only 3 options (classes A, B, and C) for allocating the address digits to the corresponding numbers. Consider the following situation as an example. Let's say that some company connecting to the Internet has only 10 computers. Since the smallest possible number of nodes are class C networks, this company should have received a range of 254 addresses (one class C network) from the organization dealing with the distribution of IP addresses. The disadvantage of this approach is obvious: 244 addresses will remain unused, since they cannot be allocated to computers of other organizations located in other physical networks. If the organization in question had 20 computers distributed over two physical networks, then it would have to be allocated a range of two class C networks (one for each physical network). In this case, the number of "dead" addresses will double.

For a more flexible definition of the boundaries between the digits of the network and host numbers within the IP address, so-called subnet masks are used. A subnet mask is a special type of 4 byte number that is used in conjunction with an IP address. The "special kind" of the subnet mask is as follows: the bits of the mask corresponding to the bits of the IP address reserved for the network number contain ones, and the bits corresponding to the bits of the host number contain zeros.

Paired with an IP address, a subnet mask eliminates the need for address classes and makes the entire IP addressing system more flexible.

So, for example, the mask 255.255.255.240 (11111111 11111111 11111111 11110000) allows you to split the range of 254 IP addresses belonging to the same class C network into 14 ranges that can be allocated to different networks.

For the standard division of IP addresses into a network number and a host number, defined by classes A, B and C, the subnet masks are of the form:

Table 2.5 - Class A, B and C subnet masks

Class	Binary form	Decimal form
	11111111 00000000 00000000 00000000	255.0.0.0
	11111111 11111111 00000000 00000000	255.255.0.0
	11111111 11111111 11111111 00000000	255.255.255.0

Since each node on the Internet must have a unique IP address, it is certainly important to coordinate the allocation of addresses to individual networks and nodes. This coordinating role is played by The Internet Corporation for Assigned Names and Numbers (ICANN).

Naturally, ICANN does not solve the problem of allocating IP addresses to end users and organizations, but is engaged in the allocation of address ranges between large organizations providing services for Internet access (Internet Service Providers), which, in turn, can interact with both smaller providers. and with end users. For example, ICANN delegated the functions for the allocation of IP addresses in Europe to the RIPE Coordination Center (RIPE NCC, The RIPE Network Coordination Center, RIPE - Reseaux IP Europeens). In turn, this center delegates part of its functions to regional organizations. In particular, Russian users are served by the Regional Network Information Center "RU-CENTER".

In this network, the allocation of IP addresses is performed using the DHCP protocol.

DHCP provides three ways to allocate IP addresses:

1) Manual distribution. In this method, the network administrator maps the hardware address (usually the MAC address) of each client computer to a specific IP address. In fact, this method of address allocation differs from manual configuration of each computer only in that address information is stored centrally (on the DHCP server), and therefore it is easier to change them if necessary.

2) Automatic distribution. With this method, each computer is allocated an arbitrary free IP address from the range specified by the administrator for permanent use.

3) Dynamic allocation. This method is similar to automatic allocation, except that the address is given to the computer not for permanent use, but for a certain period. This is called leasing an address. After the expiration of the lease, the IP address is again considered free, and the client is obliged to request a new one (however, it may turn out to be the same).

IP addresses in the course project are taken from class B and have a mask of 225.225.0.0. Issued by DHCP with binding to the MAC address to avoid illegal connections.

Table 2.6 - Assignment of subnets

House number	Number of entrances	Floor number	Subnet address
2	4	5
5	4	4
7	4	10
8	5	11

2.5 Organization of Internet access via satellite

2.5.1 Types of satellite Internet

Two-way satellite Internet means receiving data from a satellite and sending it back also via satellite. This method is very high quality, since it allows you to achieve high speeds during transmission and sending, but it is quite expensive and requires obtaining permission for radio transmitting equipment (however, the provider often takes over the latter).

One-way satellite Internet means that the user has some existing method of connecting to the Internet. As a rule, this is a slow and / or expensive channel (GPRS / EDGE, ADSL connection where Internet access services are poorly developed and limited in speed, etc.). Only requests to the Internet are transmitted through this channel. These requests go to the node of the operator of one-way satellite access (various technologies of VPN connection or traffic proxying are used), and the data received in response to these requests is transmitted to the user through a broadband satellite channel. Since most users get their data primarily from the Internet, this technology allows for faster and cheaper traffic than slower and more expensive landline connections. The volume of outgoing traffic over a terrestrial channel (and hence the cost of it) becomes quite modest (the outgoing / incoming ratio is about 1/10 when surfing the web, from 1/100 or better when downloading files).

Naturally, it makes sense to use one-way satellite Internet when the available terrestrial channels are too expensive and / or slow. In the presence of inexpensive and fast "terrestrial" Internet, satellite Internet makes sense as a backup connection option in case of loss or poor operation of the "terrestrial".

2.5.2 Equipment

The core of the satellite Internet. Carries out processing of data received from the satellite, and the extraction of useful information. There are many different types of maps, but the most famous are the SkyStar family. The main differences of DVB cards today are the maximum data rate. Also, the characteristics include the ability to decode the signal hardware, software support for the product.

There are two types of satellite dishes:

· Offset;

· Direct focus.

Direct focus antennas are a "saucer" with a circular cross-section; the receiver is located directly opposite its center. They are more difficult to set up than offset and require ascent to the satellite angle, which is why they can “collect” atmospheric precipitation. Offset antennas, due to the displacement of the focus of the "dish" (point of maximum signal), are installed almost vertically, and therefore easier to maintain. The antenna diameter is selected in accordance with the weather conditions and the signal strength of the required satellite.

The converter acts as a primary converter that converts the microwave signal from the satellite into an intermediate frequency signal. Most converters are nowadays adapted to prolonged exposure to moisture and UV rays. When choosing a converter, you should mainly pay attention to the noise figure. For normal operation, it is worth choosing converters with a value of this parameter in the range of 0.25 - 0.30 dB.

To implement the two-way method, a transmitting card and a transmitting converter are added to the required equipment.

2.5.3 Software

There are two complementary approaches to the implementation of software for satellite Internet.

In the first case, a DVB card is used as a standard network device (but only working for reception), and a VPN tunnel is used for transmission (many providers use PPTP ("Windows VPN"), or OpenVPN at the client's choice, in some cases IPIP is used. tunnel), there are other options. This disables control of packet headers in the system. The request packet goes to the tunnel interface, and the response comes from the satellite (if you do not disable header control, the system considers the packet to be an error (in the case of Windows - not so)). This approach allows you to use any application, but has a high latency. Most of the satellite providers available in the CIS (SpaceGate (Itelsat), PlanetSky, Raduga-Internet, SpectrumSat) support this method.

The second option (sometimes used in conjunction with the first): the use of special client software, which, due to the knowledge of the protocol structure, makes it possible to speed up the receipt of data (for example, a web page is requested, the server views it from the provider and immediately, without waiting for a request, sends pictures from this pages, assuming that the client will request them anyway; the client side caches such responses and returns them immediately). Such client side software usually acts as an HTTP and Socks proxy. Examples: Globax (SpaceGate + others on request), TelliNet (PlanetSky), Sprint (Raduga), Slonax (SatGate).

In both cases, it is possible to "share" traffic over the network (in the first case, sometimes you can even have several different subscriptions of a satellite provider and share a dish due to special configuration of a machine with a dish (requires Linux or FreeBSD, under Windows requires third-party software)).

Some providers (SkyDSL) necessarily use their software (playing the role of both a tunnel and a proxy), often also performing client shaping and preventing the sharing of satellite Internet between users (also preventing the use of anything other than Windows as an OS) ...

2.5.4 Advantages and Disadvantages

The following advantages of satellite Internet can be distinguished:

The cost of traffic in the hours of least capacity utilization

Independence from land lines (when using GPRS or WiFi as a request channel)

High final speed (reception)

· The ability to watch satellite TV and "fishing from the satellite"

The ability to freely choose a provider

Disadvantages:

The need to purchase special equipment

The complexity of installation and configuration

Generally lower reliability compared to ground connection (more components needed for smooth operation)

The presence of restrictions (direct visibility of the satellite) on the installation of the antenna

· High ping (delay between sending a request and receiving a response). This is critical in some situations. For example, when working in the interactive mode Secure Shell and X11, as well as in many multiplayer online systems (the same SecondLife cannot work at all via satellite, Counter Strike shooter, Call of Duty - works with problems, etc.)

· In the presence of at least pseudo-unlimited tariff plans (like "2000 rubles for 40 Gb for 512 kbps further - unlim but 32 kbps" - TP Active-Mega, ErTelecom, Omsk), the terrestrial Internet is already becoming cheaper. With the further development of cable infrastructure, the cost of terrestrial traffic will tend to zero, while the cost of satellite traffic is strictly limited by the cost of launching a satellite and its reduction is not planned.

When working through some operators, you will have a non-Russian IP-address (SpaceGate Ukrainian, PlanetSky - Cypriot, SkyDSL - German), as a result of which the services that are used for some purpose (for example, we start up only from the Russian Federation) determine the user's country, will not work correctly.

· The software part - not always "Plug and Play", in some (rare) situations it can be difficult and it all depends on the quality of the operator's technical support.

The course project will use two-way satellite Internet. This will allow achieving high data transfer rates and high-quality packet transmission, but will increase the project implementation costs.

3. Safety when working at height

Work at a height is considered to be all work that is performed at a height of 1.5 to 5 m from the ground surface, floor or working floor, on which work is performed from mounting devices or directly from structural elements, equipment, machines and mechanisms, during their operation, installation and repair.

Persons who have reached 18 years of age are allowed to work at height, who have a medical certificate of admission to work at height, who have been trained and instructed in safety precautions and who have received admission to independent work.

Work at heights must be carried out from scaffolding (scaffolding, scaffolding, decks, platforms, telescopic towers, suspended cradles with winches, ladders and other similar auxiliary devices and devices) that ensure safe working conditions.

All paving means used to organize workplaces at height must be registered, have inventory numbers and plates indicating the date of the conducted and the next tests.

Laying of decks and work on random supports (boxes, barrels, etc.) is prohibited.

Control over the condition of the means of paving should be carried out by persons from among the engineering and technical personnel who are appointed by an order for the enterprise (oil depot).

Workers of all specialties must be provided with safety belts and, if necessary, with protective helmets to perform even short-term work at a height from stairs.

Safety belts issued to workers must be labeled with a test mark.

It is prohibited to use a defective harness or with an expired test period.

Work at heights is done in the daytime.

In emergency cases (when troubleshooting), on the basis of an order from the administration, work at a height at night is allowed in compliance with all safety rules under the supervision of engineering personnel. The workplace should be well lit at night.

In winter, when working outdoors, paving equipment should be systematically cleaned of snow and ice and covered with sand.

With a wind force of 6 points (10-12 m / s) or more, with a thunderstorm, heavy snowfall, icy conditions, work at a height in the open air is not allowed.

Do not arbitrarily rebuild decking, scaffolds and fences.

Electric wires located closer than 5 m from the stairs (scaffolds) must be protected or de-energized while the work is being performed.

Workers are obliged to perform the assigned work, observing the labor protection requirements set out in this instruction.

For violation of the requirements of the instructions relating to the work performed by them, workers are liable in the manner prescribed by the Internal Regulations.

Simultaneous production of works in 2 or more tiers vertically is prohibited.

Do not fold the tool at the edge of the platform, or throw it and materials on the floor or the ground. The tool should be stored in a special bag or box.

It is forbidden to throw any objects for feeding to the worker at the top. The feeding should be done using ropes, to the middle of which the necessary items are tied. The other end of the rope should be in the hands of the worker standing below, who keeps the objects being lifted from swinging.

Anyone working at height must ensure that there are no people underneath his workplace.

When using ladders and stepladders, it is prohibited:

· Work on unreinforced structures and walk on them, as well as climb over fences;

· Work on the top two rungs of the ladder;

· Be two workers on a ladder or on one side of a stepladder;

· Move up the stairs with a load or with a tool in hand;

· Use stairs with steps sewn with nails;

· Work on a faulty staircase or on the steps doused with slippery oil products;

· Build up stairs in length, regardless of the material from which they are made;

· Stand or work under the stairs;

· Install ladders near rotating shafts, pulleys, etc .;

· To carry out work with a pneumatic tool;

· To carry out electric welding works.

4. Economic costs of building a local network

This course project involves the following economic costs.

Table 4.1 - List of economic costs *

Name	Units	Qty	per unit (rub.)	Amount (rub)
Fiber-optic cable EKB-DPO 12	m	708,5	36	25506
FTP cable 4 pairs cat.5e<бухта 305м>Exalan + -	bay	25	5890	147250
D-Link DGS-3200-16 switch	PC	2	13676	27352
D-Link DGS-3100-24 switch	PC	5	18842	94210
D-link DFL-1600 router	PC	1	71511	71511
IBM System x3400 M2 7837PBQ Server	PC	1	101972	101972
APC SUA2200I Smart-UPS 2200 230V UPS	PC	2	29025	58050
RJ-45 connectors	Pack (100pcs)	3	170	510
MT-RJ connectors	PC	16	280	4480
Server cabinet	PC	1	2100	2100
Router cabinet	PC	1	1200	1200
Switch cabinet	PC	7	1200	8400
D-Link DMC-805G Converter	PC	16	2070	33120
Satellite dish + DVB card + converter	PC	1	19300	19300
Staples 6mm	Pack (50 pcs)	56	4	224
Total				595185

Economic costs do not include installation costs. Cables and connectors are rated with a margin of ~ 30%. Prices are indicated at the time of creation of the course project, including VAT.

Conclusion

In the process of developing the course project, a local area network was created with access to the global network. An informed choice of the type of network was made based on consideration of many options. Expansion of the network is envisaged for its further growth.

In the course design, class B IP addresses were used, since there are one hundred and one workstations on the network. The assignment of addresses was carried out by the DHCP protocol. The entrance number was used as the subnet address.

The point for calculating the required amount of equipment contains data and calculations of the equipment used. The development cost is 611,481 rubles. All calculated parameters meet the criteria for network operability.

A short network plan has been drawn up, where all the characteristics of the equipment used are indicated. The Power Tool Safety section explains how to handle and work with a power tool.

In general, the course project contains all the necessary data for building a local area network.

List of sources used

1.http: //www.dlink.ru;

2.http: //market.yandex.ru;

3.http: //www.ru.wikipedia.org.

4. Computer networks. Training course [Text] / Microsoft Corporation. Per. from English - M .: "Russian edition" LLP "Channel Trading Ltd.", 1998. - 696s.

5. Maksimov, N.V. Computer networks: Textbook [Text] / N.V. Maksimov, I.I. Popov - M .: FORUM: INFRA-M, 2005 .-- 336s.

their regulatory documents.

The procedure for designing local networks

Typical LAN design can be performed in several stages and provides for the determination of the following characteristics:

· Main and secondary tasks assigned to the network;

· Functionality of the network;

· The throughput of various sections and the nature of the transmitted information;

· Type of installed network;

· The possibility of laying cables indoors and ensuring their safe operation;

· The structure of the LAN, its hierarchy and main parts by departments, workplaces;

· The possibility of further expanding the network;

· The need to connect to existing local networks of the enterprise and to the global Internet;

· The possibility of using information security tools.

All work that provides for the design of computer networks is carried out in strict accordance with the preliminary plan developed on the basis of the TOR. One of the priority conditions is ease of maintenance, installation, and, if necessary, dismantling of the enterprise's local network.

Initial data

The importance of this stage is associated both with the need to streamline the requirements for the created drug and its individual components to ensure the possibility of making informed concrete decisions in the future, and with its justification.

When creating a new network for an enterprise, it is advisable to consider the following factors:

· Required network size (currently, in the near future and projected for the future).

· Structure, hierarchy and main parts of the network (by divisions of the enterprise, as well as by rooms, floors and buildings of the enterprise).

· The main directions and intensity of information flows in the network (at present, in the near future and in the long term). The nature of the information transmitted over the network (data, digitized speech, images), which directly affects the required transmission rate (up to several hundred Mbps for high-definition television images).

· Technical characteristics of equipment (computers, adapters, cables, repeaters, hubs, switches) and its cost.

· Possibility of laying the cable system in and between rooms, as well as measures to ensure the integrity of the cable.

Network maintenance and control reliability and safety.

· Requirements for software in terms of permissible network size, speed, flexibility, differentiation of access rights, cost, information exchange control capabilities, etc.

· The need to connect to global or other local networks.

It is quite possible that after studying all the factors, it turns out that it is possible to do without a network, thereby avoiding rather large costs for equipment and software, installation, operation, support and repair of the network, salaries of maintenance personnel, etc.

Network on compared to stand-alone computers, it generates many additional problems: from the simplest mechanical (computers connected to a network are more difficult to move from place to a place) to complex information (the need to control shared resources, prevent viruses from infecting the network). In addition, network users are no longer as independent as users of autonomous computers, they need to adhere to certain rules, to obey the established requirements that they need to be taught.

Finally, net sharply raises the question of information security, protection against unauthorized access, because from any computer on the network you can read data from shared network drives. Protect one a computer or even a few singles are much easier than a whole net... Therefore, it is advisable to start installing a network only when work becomes impossible without a network, unproductive, when the lack of intercomputer communication hinders the development of the business.

Requirements and solutions for sizing and network structures, network hardware and software will be discussed in the following sections. At the beginning of the network design, it is necessary to conduct a complete " inventory"existing computers and their software, as well as peripheral devices (printers, scanners, etc.). This will allow you to eliminate unnecessary duplication (equipment and software can now be shared resources), as well as set the tasks of modernization (upgrade) of both hardware and software. To correctly determine the characteristics of computers, it is advisable to use special diagnostic programs or built-in OS programs (for example, in the OS Windows Millennium is program"System Information" from the Utilities section and program"System" from the control panel). You should choose such program options that ensure that the correct data is obtained ("old" diagnostic programs may incorrectly indicate the type of processor and OS version), and data storage in the file (this is especially valuable with a large number of computers). In addition, you should pay attention to the presence of a built-in network card or network controller on the system board, as well as the type of network standards they support (usually Ethernet network on twisted pair, but it is important to know its type - 10/100/1000 Mbit / s). Not all of the characteristics of computers that are important when combining them into net, can be determined in the ways described above. From the accompanying documentation to the computer or after opening the system unit, it is possible and necessary to determine the number and type of free expansion slots (connectors), as well as the maximum power power supply. This is necessary to assess the possibility of installation in a computer new boards.

Equipment selection

When choosing network equipment, many factors must be taken into account, in particular:

· The level of equipment standardization and its compatibility with the most common software tools;

· Speed ​​of information transfer and the possibility of its further increase;

· Possible network topologies and their combinations (bus, passive star, passive tree);

· exchange control method online ( CSMA/ CD, full duplex, or marker method);

· Permitted types of network cable, its maximum length, immunity from interference;

The cost and technical characteristics of specific hardware (network adapters, transceivers, repeaters, hubs, switches).

All this is often neglected, but in vain: replace software relatively simple, but the replacement of equipment, especially the laying of the cable, is sometimes very expensive, and sometimes it is simply impossible. In the first queue the applicability for the considered network case should be analyzed Ethernet, as the most popular, inexpensive and developmentable ( Fast Ethernet and Gigabit Ethernet).

The problem of choosing the type of cable was considered in sufficient detail earlier. Assuming that there is a choice in this case, it is worth repeating the main arguments in favor of one or another choice (see Table 15.1).

Table 15.1. Arguments when choosing a cable type
Cable type	Choice arguments
per	vs
unshielded twisted pair UTP(category 3 or higher)	· Affordability; · Availability of tools for installing connectors (RJ45); · Convenience of cable laying (flexible); · Relative ease of repair in case of damage; · Support for promising high-speed networks (Fast and Gigabit Ethernet) when using cable category 5 or higher.	· Relatively low resistance to electromagnetic interference; · Relatively small permissible distances of cable connections, especially for high-speed networks; · Impossibility of use in external sections of connections (between buildings).
shielded twisted pair STP (braided shield) 1	· Increased immunity to electromagnetic interference.	Slightly higher price compared to cable type UTP.
shielded twisted pair FTP (foil shield) 2	similar to the previous type of cable
multimode fiber optic cable	· Practical insensitivity to external electromagnetic interference and the absence of its own radiation; · Support for promising high-speed networks, including over distances inaccessible using twisted pair.	· Relatively high price of cable and network equipment; · The complexity of the installation (requires a special tool and highly qualified personnel); · Low maintainability; Sensitivity to environmental factors (may cause turbidity fiber optic).
singlemode fiber optic cable	· Improved technical characteristics in comparison with multimode cable (the possibility of increasing the transmission speed or the length of the connections).	· Higher price; · Complex installation and repair.
wireless connections (radio and infrared)	· Elimination of the need to organize a cable system; · Mobility of workstations (ease of moving them inside buildings or near a central computer with a radiating antenna); · The possibility of organizing global networks (using radio channels and satellite communications).	· Relatively expensive equipment; · Strong dependence of the reliability of the connection on the presence of obstacles (for radio waves) and dust in the room (for infrared channels); · Rather low transmission speed (maximum up to several Mbit / s) and the impossibility of its significant increase.

Currently, for the organization of local networks in the overwhelming majority of cases, unshielded twisted pair UTP... More expensive shielded twisted pair options, fiber optic cable or wireless connections are used in enterprises where there is a really urgent need for it. For example, optical fiber can be used for communication between remote network segments without loss of speed. Recommendations by organization of the cabling system, including those contained in the standards for structured cabling systems ( SCS), are discussed in a separate section "Designing a cable system" Lectures 16.

Another important task is the choice of computers. If workstations or non-dedicated servers usually use those computers that already exist in the enterprise, then dedicated server it is advisable to purchase specifically for the network. It is better if it is a high-speed specialized a computer-server, designed with the specific needs of the network in mind (such servers are produced by all major computer manufacturers).

Server Requirements:

· The fastest processor (Microsoft recommends a processor with a clock speed of at least 500 MHz for its Windows Server 2003 operating system). The typical processor clock speed for a server is now 2-3 GHz. For large networks, multiprocessor servers are also used (sometimes up to 32 processors).

· Large amount of RAM (Microsoft recommends at least 256 megabytes of memory for its Windows Server 2003 operating system, the same requirements of Novell for NetWare 6). Typical server RAM is now 512MB-20GB. A large amount of server memory is even more important than the speed of the processor, since it allows efficient use of caching of disk information, storing copies of those disk areas with which the most intensive exchange is carried out in memory.

· Fast hard drives with large capacity. A typical server disk space is now 150-500 GB. Drives must be compatible with network operating system(that is, their drivers must be included in the driver set supplied with the OS). SCSI drives are widely used, which are faster than traditional IDE drives. Servers often provide hot swapping of disks (without turning off the server power), which is very convenient.

· Specialized servers already contain network adapters with optimal characteristics. If a regular personal computer is used as a server, then the network adapter for it should be chosen the fastest.

· Video monitors, keyboards and mice are not required server accessories, as the server usually never operates in the normal computer mode.

If it is possible to select computers for workstations, then it is worth analyzing the feasibility of using diskless workstations (with loading the operating system through net). This will immediately reduce the cost network as a whole or will allow at the same cost to buy better computers: with fast processors, with good monitors, with a lot of RAM. However, the use of diskless computers is not considered the best solution at present. Indeed, in this case, all the information a computer gets through net and transfers to net which can cause excessive network load. Diskless workstations are acceptable only for small networks (no more than 10-20 computers). Ideally, a significant part of all information flows (at least 80%) should remain inside the computer, and access to network resources should be available only in case of actual need. Thus, the aforementioned "80/20 rule" works in this case as well.

By eliminating the use of floppy disks on each computer in the network, you can significantly increase it steadiness to viruses and unauthorized access to data. A floppy disk drive may well be on only one workstation in a segment, or even an entire network. Moreover, this work station should be monitored network administrator... It can be located in a separate room along with hubs, switches, routers.

For any network, the situation of power outages is extremely critical. Despite the fact that many network software special measures are taken against this, as well as against other hardware failures (for example, disk duplication), the problem is very serious. Sometimes a power outage can completely and permanently remove net out of service.

Ideally, all servers on the network (preferably workstations) should be protected from power outages. The easiest way to achieve this is if server there is only one in the network. In the event of a power failure, the uninterruptible power supply transfers power to the connected computer from the battery and sends a special signal to the computer, which in a short time terminates all current operations and saves the data to disk. When choosing an uninterruptible power supply, one must first of all pay attention to the maximum power, which it provides, and for the time it maintains the nominal voltage level (this time ranges from several minutes to several hours). The cost the device is quite high (up to several thousand dollars). Therefore, it is advisable to use one uninterruptible power supply for two or three servers.

Most resistant to failure power supply portable computers (laptops). The built-in battery and low power consumption ensure their normal operation without external power supply for one to two hours or even more. Considering the low radiation and high image quality of the monitors of these computers, then it is worth seriously considering using laptops as workstations, and probably not too powerful, non-dedicated server. Moreover, many laptops have fairly good quality built-in network adapters. It is especially convenient to use laptops in peer-to-peer networks with many servers. The use of external uninterruptible power supplies in such cases becomes too expensive.

In addition to the listed problems, the network designer has to solve problems associated with the choice of network adapters, repeaters, hubs, switches and routers, but this has been covered in the previous chapters. It should only be noted that performance network and its reliability determined by the lowest quality component. When buying expensive hubs or switches, you shouldn't skimp on network adapters, for example. The converse is also true. It is desirable that all equipment components match each other as closely as possible.

Defining the network model

The network model defines the way data is stored and the location of the communication lines over which this data is transmitted. Each network can implement one or several standard models at once. Currently, there are four most common models that provide users with access to networked applications and data:

1. Distributed environment (mainframe environment)

This model was the very first and remains popular to this day. All network resources of this model are located on a server, which is responsible for managing and storing all company data. Each network user contacts him from his video terminal or diskless workstation to start processes on the server.

The main advantages and disadvantages of this environment:

The server is the most vulnerable component to network outages

No need to upgrade client workstations to support new applications

Decreased network performance when the server is overloaded

Impossibility of further modernization and expansion in case of wrong server choice

Uncomplicated management of security issues of physical access to the server.

2. Client / server environment

At the current stage of development of technologies for sharing data and resources, this model is the most popular and can be implemented in organizations of all sizes. Here, the server is only used to provide access to applications and store generated data. All data processing is performed on the workstation, which improves network performance and reduces server load.

The main advantages and disadvantages of a client / server environment are:

The need for more careful planning compared to other planning models

The ability to operate workstations even in the absence of a server

The need for upgrading the network to increase the performance of not only the server, but also the workstation

Insufficient security of data stored on workstations

Expandable to fieldbus level

3. Peer-to-peer environment

This model is designed for small (up to 15 workstations) local area networks and is most often deployed in small offices. The principle of its operation is based on the fact that each workstation operates in server mode, providing access to its data and devices to any other station that has the necessary permissions for this.

Advantages and disadvantages of the peer-to-peer model:

Attractive cost / performance ratio due to the lack of a dedicated server

Workstations have access to all resources

Lack of centralized management and security

The impossibility of converting to a large network

Possibility of failure of the entire network after failure of an individual workstation

4. WWW-based environment

The structure of the model is reminiscent of a mainframe environment, in which a central server provides users with its "pages" of information to view and interact with. Each user of such a network can use these pages either on their local machine or on a server.

The main advantages and disadvantages of this environment are:

Tempting cost / performance ratio when used to connect LAN and WAN

The ability to install and update versions of applications without the need for direct interaction with client workstations

The most vulnerable link in the network to failures is the web server

Insufficiently reliable security due to the possibility of external access to the network

Deployable in low bandwidth or high schedule environments

Possibility of integration with the Internet.

Choice of software

Network OS

After selecting the optimal network model and listing the required applications, network professionals and users should identify possible network operating systems. The factors taken into account when making this decision are very similar to those discussed above:

Cost and licensing scheme

Easy to install and configure

Ease of use

Minimum maintenance effort

Affordable level of technical support

• 
  Computer resource requirements

Hardware support

Possibility of subsequent modernization

Level of support for independent developers (both application software and the OS itself)

System Administrator Training Opportunities

Choice of hardware

The selected software6 defines the hardware requirements. Network hardware requirements can be roughly divided into three main types:

Server hardware requirements

Workstation hardware requirements

Requirements for peripheral devices (printers, modems, scanners, etc.)

It is recommended to install equipment from a company that is a leader in this market area, offers good support for its products, and provides solutions for compatibility issues between its hardware and hardware from other manufacturers.

The choice of server hardware is almost entirely determined by the network operating system used, and the hardware of the workstations is determined by the applications that you plan to run on them. It is desirable to divide user equipment into several categories. For example, senior PC models are recommended for software developers, CAD developers, artists, analysts of the firm, for assistant administrators, sales agents, secretaries, etc. - standard PC models, for executives, managers - older PC models or, if they often move, then powerful portable PCs.

The last point to consider is peripherals. Typically, their choice is determined by the commercial requirements of each department. For example, is there a need for high quality graphics printing? Do you need high print speeds? Do I need a color printer to work?

It is advisable to locate peripheral devices in those places where they will be accessible to the maximum number of users.

When preparing the final documentation for the network hardware, it is necessary to draw up the following basic specifications:

Desktop Hardware:

System manufacturer and model (specify separately for different categories of users)

CPU

Hard drives

Network adapters

Server hardware

System make and model

CPU

Hard drives (specify all backup methods: mirroring, duplication, using RAID arrays)

Network adapters

Additional peripherals

Peripheral make and model

Site specific settings

Interfaces used (serial, parallel or other)

Network traffic assessment

After choosing the final configuration of the hardware and software of the network, it is necessary to evaluate the volumes and types of data transmitted in it in accordance with the data flow diagram. This will allow determining the possible periods of maximum and average network load, assessing its scalability, analyzing the placement of information on servers and distributed processing of information within workgroups. This will make it possible to optimize the network architecture for equal load distribution, properly segment it, select the necessary network devices such as hubs, switches, routers and gateways.

Documentation

The network project documentation should contain the following information:

• 
  Commercial requirements
• 
  Logic diagram
• 
  Physical diagram
• 
  Application software (cost estimate)
• 
  Network software (cost estimate)
• 
  Hardware (servers, workstations and peripherals) (cost estimate)
• 
  Network hardware (cost estimate)
• 
  Total cost estimate

It is necessary for each item to provide a brief explanation of what alternatives existed and why one or another solution was chosen.

Administration

Network administration describes all aspects of installing and maintaining users / groups or files / directories. Although the meaning of this term is the same for all network environments, the work of network administrators at different sites differs significantly.

Administrators' technical knowledge and skills also differ significantly. The following list contains questions that a network administrator should know the answers to:

How do I register new users?

How do I delete already registered users?

What is the structure of the volumes on the server?

What directories are on separate volumes?

How are the reservation activities planned?

Are there any special requirements for the node configuration?

What is the security level of each department or user directory?

Is it necessary to copy data to a central server in order to back it up in case of a local equipment failure?

How is the server configured?

What are the possible server failures associated with?

The following list describes all the main responsibilities of network administrators to keep the server running smoothly.

To organize the management and maintenance of the network, documentation is required, which would contain the following main sections:

Working with users

Custom naming conventions

User registration and deletion rules

Information management

Volume naming conventions

Directory structure (applications, user directories, department directories)

Directory size limits (optional)

Network management

Server naming conventions

Information about routers and gateways

Safety

Logon scripts / privileges of different departments

Restricting access with passwords

Defining access hours

Recovery tools (boot disks, bad sector editors, certain server configuration files, etc.).

Tracking (keeping statistics), resolving emerging problems

To maintain the operational state of the network, it is necessary to develop recovery plan post-emergency and network support plan. A typical network recovery plan includes the following points:

Determination of the severity levels of all applications and systems (essential, vital, critical)

Medium system descriptions (electrical, heating / cooling)

Identifying the teams responsible for resolving the failures and the situations in which these teams should be contacted

Determining the types of support to be provided by groups

Determining the characteristics of the hardware (this information is taken from the documentation)

Assessment and preparation of a contingency plan (downtime, replacement, offline operation)

Choosing the manager who should be alerted first of a network outage

Determination of actions in non-standard situations (fire, bomb threat, spontaneous action)

Scheduling outages and testing of critical systems

Despite the seemingly triviality of these points, they are the main points not only for the correct functioning of the network, but also for a successful career as a network administrator.

The network maintenance department is also responsible for user support , organization of events for their training and assistance in solving their problems. Support can be organized in the form of e-mail, a central database to which users contact with questions, in the simplest case - telephone communication.

Keeping statistics and further analysis of failures of a certain type (some type of equipment constantly fails, there are certain factors affecting the stability of applications) will make it possible to make the right decision about the need to upgrade or replace any component of the network environment.

The main stages of LAN design

Before performing work on the installation of a LAN, measures are taken to develop and design local networks. Various specialists can be involved in this process, who must take into account all the design features of the building and individual rooms where the LAN is planned to be laid. The result is a technical project drawn up
in accordance with the rules and regulations adopted in the Russian Federation. It includes a wiring diagram
local network, a description of its main characteristics, indicating the regulatory
their regulatory documents.

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• Introduction
• 1.6 Choice of technologies
• Conclusion

Introduction

The topic of my course work was the process of designing a local area network. This topic is quite relevant, as it is due to the worldwide trend of connecting computers in a network. Computer Computing network is a collection of computers connected by communication lines. Cables, network adapters, and other communication devices are called communication lines. We can say that all network equipment operates under the control of application software.

The relevance of the topic is determined by the fact that computer networks have become part of our life. They are used in almost all spheres of life: from education to production management, from stock exchange settlements to home WI-FI networks. On the one hand, they are a special case of distributed computer systems, and on the other hand, they can be considered as a means of transmitting information over long distances, for which they use data coding and multiplexing methods that have been developed in various telecommunication systems.

Purpose: To design a local computing group of computer classes of an educational institution.

Research object: The process of designing a local area network.

Research methods, which consist in the systematization and analysis of educational and regulatory and technical literature, as well as an Internet resource, the recommendation of manufacturers of telecommunications equipment and modern standards.

Subject of research: Search and processing of knowledge about the subject of research will be carried out with the help of educational materials specified in the list of literature and Internet resources.

Work tasks:

1. Theoretical substantiation of the construction of a computer local area network;

2. Elaboration of the prerequisites and conditions for the creation of a computer network;

3. Creation of a project of a computer local network.

1. Theoretical substantiation of the construction of a computer local network

1.1 Local and global networks. Networks of other types of classification

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

A local computer network is a distributed data processing system covering a small area (up to 10 km in diameter) inside institutions, universities, banks, offices, etc.

· PAN is a personal network designed for interaction of various devices belonging to the same owner.

· LAN (LAN) - local area networks with a closed infrastructure before reaching service providers. The term "LAN" can describe both a small office network and a large factory network. Local networks are closed-type networks, access to them is allowed only to a limited circle of users, for whom work in such a network is directly related to their professional activities.

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

· MAN - metropolitan area networks between institutions within one or several cities, connecting many local area networks.

· WAN - a global network that covers large geographic regions, including both local networks and other telecommunication networks and devices.

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

By control method

TO client / server - one or several nodes (their name is servers) are allocated in them, performing control or special service functions in the network, and the remaining nodes (clients) are terminal, users work in them. Client / server networks differ in the nature of the distribution of functions between servers, in other words, according to the types of servers. With the specialization of servers for certain applications, we have a network of distributed computing. Such networks are also distinguished from centralized mainframe systems;

Peer-to-peer - networks in which all nodes are equal; Since in general, a client is an object (device or program) that requests some services, and a server is an object that provides these services, then each node in peer-to-peer networks can perform the functions of both a client and a server.

By access method

Tee A typical data transmission medium in local computer networks is a piece (segment) of a coaxial cable. Nodes - computers and possibly common peripheral equipment - are connected to it through the equipment of the end of the data channel. Since the data transmission medium is common, and requests for network exchanges from nodes appear asynchronously, the problem of sharing the common medium between many nodes arises, in other words, the problem of providing access to the network. Network access - interaction of a station (network node) with a data transmission medium to exchange information with other stations. Media access control is the sequencing in which stations access the media. Distinguish between random and deterministic access methods. Among the random methods, the best known method is carrier sense multiple access and collision detection.

1.2 Comparative analysis of different network topologies

At the moment, there are ways to combine computers. The way of describing the network configuration, the layout and connection of network devices is characterized by the term network topology.

Let's highlight the most common network topologies:

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

Ring - the nodes are connected by a ring data line (only two lines are suitable for each node); data passing through the ring becomes available to all network nodes one by one;

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

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

The term topology, or network topology, refers to the physical location of computers, cables, and other components of a network.

Topology is a standard term used by professionals to describe the basic layout of a network. In addition to the term "topology", the following are also used to describe the physical layout:

Physical location; layout;

Diagram;

The topology of the network determines its characteristics. In particular, the choice of a particular topology affects:

The composition of the required network equipment;

Characteristics of network equipment;

Network expansion possibilities;

Network management method.

To share resources or perform other network tasks, computers must be connected to each other. Most networks use a cable for this purpose.

However, simply plugging your computer into a cable that connects other computers is not enough. Different types of cables, combined with different network cards, network operating systems, and other components, also require different positioning of computers.

Comparative analysis of network topologies

The comparative analysis was carried out on the basis of the following indicators:

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

2) Reliability. It is determined by the presence of bottlenecks, upon failure of which the network ceases to function. Reliability is also characterized by the presence of alternative paths due to which, in case of failure of individual channels, communication can be established bypassing the failed section.

3) Network performance. It is determined by the number of data blocks transmitted over the network per unit of time. At the same time, it is necessary to take into account the possibility of speed reduction due to network conflicts.

4) Delivery time of messages. May not necessarily be measured in time units.

5) Topology cost. It is determined by both the cost of the equipment and the complexity of the network implementation.

Let's compile a table comparing various topologies according to the indicated characteristics. The features will be evaluated with values ​​from 1 to 5, with 1 being the best value.

Table 1

Comparative analysis of network topology

Structural simplicity and cost are two very closely related metrics. In terms of the number of communication channels, the simplest topology is the common bus, which has only 1 communication channel. The network is built on the basis of a network card. The ease of adding new computers also adds to the benefits of this topology. Thus, the common bus is by far the simplest and cheapest topology. Star and tree topologies can also be classified as relatively cheap, which is associated with a small number of types of connections between nodes, i.e. each computer is directly connected to the central site. Next comes the ring topology. In it, the number of communication channels is equal to the number of nodes. Fully connected topology is the most complex and expensive, respectively. This makes it impractical to use such a topology when building large networks. When building global networks, the most widespread is multi-connected \ mesh topology. It occupies an intermediate position in these indicators, but there is no alternative to this topology in global networks, because such networks are not built from scratch, but integrates existing networks.

Reliability. According to this indicator, the leader is fully connected topology. It has no bottlenecks and has the maximum possible number of alternative paths in the event of a link failure. Least reliable topologies: common bus, star and tree. The ring topology occupies an intermediate position, as well as multi-connected.

Network performance. If we 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 are simultaneously in the network. With an increase in the number of packets, performance increases and at some value saturation occurs. Saturation is usually associated with some node or channel in the network, the load of which is close to 1. Therefore, when building such a network, they try to ensure equal bandwidth for all channels, which provides maximum performance for a fully mesh topology and minimum performance for a common bus.

Time of delivery. Should be analyzed provided that there are no network bottlenecks. In this case, delivery time is directly related to the number of hops, i.e. communication channels between neighboring nodes. The 1-hop delivery time is provided by a fully connected topology. The longest delivery time with a large number of nodes in a network with a ring topology. The most difficult time to estimate delivery time is in a shared bus topology. This is due to the fact that the bus is used by all nodes, and if the delivery time for one node is minimal, then other nodes wait for their turn, and the delivery time increases dramatically. In addition, in the common bus topology, the delivery time is influenced by collisions, i.e. collisions of packets.

The analysis presented is qualitative and cannot be used to quantify. The decision to use a particular topology should be made on the basis of taking into account all the parameters. In this case, it may turn out that a more complex topology is cheaper than a simpler one.

Based on the material presented, it was decided to use the "star" topology, since it has the greatest efficiency among the presented ones.

1.3 Analysis of sources of standardization of networks. Structure of the IEEE 802.x standard

In 1980, the IEEE Institute organized the 802 LAN Standardization Committee, which resulted in the adoption of the IEEE 802-x family of standards, which provide recommendations for the design of the lower layers of local networks. Later, the results of the work of this committee formed the basis for a set of international standards ISO 8802-1 ... 5. These standards were based on the very common proprietary standards for Ethernet, ArcNet, and Token Ring.

IEEE 802.X family standards cover only two lower layers of the seven-layer 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 higher levels, starting with the network, have largely common features for both local and global networks.

The specificity of local networks is also reflected in the division of the link layer into two sublevels, which are often also called layers. The link layer is divided in local networks into two sublevels:

Logical Link Control, LLC;

Media Access Control (MAC).

The MAC layer appeared due to the existence of a shared data transmission medium in local networks. It is this level that ensures the correct sharing of the common environment, providing it in accordance with a certain algorithm at the disposal of one or another station on the network. After access to the medium is obtained, it can be used by a higher level - the LLC level, which organizes the transfer of logical data units, information frames, with different levels of quality of transport services. In modern local area networks, several protocols of the MAC layer have become widespread, implementing various algorithms for accessing a shared medium. These protocols fully define the specifics of technologies such as Ethernet, Fast Ethernet, Gigabit Ethernet, Token Ring, FDDI, l00VG-AnyLAN.

The LLC layer is responsible for the transfer of data frames between nodes with varying degrees of reliability, implements the functions of an interface with an adjacent network layer. It is through the LLC layer that the network protocol requests from the link layer the transport operation it needs with the required quality.

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

The IEEE 802 standards have a fairly clear structure, shown in Figure 1.1.

Figure 1.1

Today Committee 802 includes the following set of subcommittees, which include both those already mentioned and some others:

802.1 - Internetworking - networking;

802.2 - Logical Link Control, LLC - logical data transmission control;

802.3 - Ethernet with CSMA / CD access method;

802.4 - Token Bus LAN - local area networks with Token Bus access method;

802.5 - Token Ring LAN - local area networks with Token Ring access method;

802.6 - Metropolitan Area Network, MAN - metropolitan area networks;

802.7 - Broadband Technical Advisory Group - Broadband technical advisory group;

802.8 - Fiber Optic Technical Advisory Group - technical advisory group for fiber optic networks;

802.9 - Integrated Voice and data Networks - integrated voice and data networks;

802.10 - Network Security - network security;

802.11 - Wireless Networks - wireless networks;

802.12 - Demand Priority Access LAN, l00VG-AnyLAN - local area networks with priority access on demand method.

Based on the analysis performed, it was decided to use the following IEEE 802.3 subcommittee in the design of the local area network. The specifications of this subcommittee will be discussed below.

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

The cabling system is the foundation of any network. Structured cabling systems are the answer to the high demands on cabling quality.

A structured cabling system is a collection of communication elements — cables, connectors, connectors, marshalling panels, and cabinets — that meet standards and allow for the creation of regular, easily expandable link structures.

The structured cabling system consists of three subsystems: horizontal (within a floor), vertical (between floors), and a campus subsystem (within a single area with multiple buildings).

The horizontal subsystem is characterized by the presence of a large number of branches and cross-links. The most suitable cable type is Category 5 unshielded twisted pair cable.

The vertical subsystem consists of longer cable sections, the number of branches is much less than in the horizontal subsystem. The preferred cable type is fiber optic.

The campus subsystem is characterized by an irregular structure of connections with the central building. The preferred cable type is fiber optic in special insulation.

The building cabling system is built in excess, since the cost of the subsequent expansion of the cabling system exceeds the cost of installing redundant elements.

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

When transferring data between computers, the packet contains not only the transmitted data, but also the address of the receiving computer.

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

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

This is a very simplified description of how hubs and switches work, but it gives an overview of the 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, routers have built-in switches, not hubs. ...

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

1.5 Cable selection. The main types of cables and their characteristics

Category 1 cables are used where the transmission speed requirements are minimal. Typically this is a cable for digital and analog voice and low speed (up to 20 Kbps) data transmission.

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

Category 3 cables were standardized in 1991 when the Telecommunications Cabling Systems for Commercial Buildings Standard (EIA-568) was developed, from which the current EIA-568A standard was then developed. The EIA-568 standard defines the electrical characteristics of Category 3 cables for frequencies up to 16 MHz, thus supporting high-speed network applications. Category 3 cable is designed for both data and voice transmission.

Category 4 cables are a slightly improved version of Category 3 cables. Category 4 cables are required to withstand tests at a transmission frequency of 20 MHz and provide increased noise immunity and low signal loss. Category 4 cables are well suited for long distance applications (up to 135 meters) and 16 Mbps Token Ring networks. In practice, they are rarely used.

Category 5 cables have been specifically designed to support high-speed protocols. Therefore, their characteristics are determined in the range up to 100 MHz. Most of the new high-speed standards are based on Category 5 twisted pair cable. This cable operates protocols with a data transfer rate of 100 Mbit / s - FDDI, Fast Ethernet, l00VG-AnyLAN, as well as faster protocols - ATM at a speed of 155 Mbit / s, and Gigabit Ethernet at a speed of 1000 Mbit / s (Gigabit Ethernet option Category 5 twisted pair cable became standard in June 1999). Category 5 cable replaced Category 3 cable, and today all new cable systems in large buildings are built on this type of cable (in combination with fiber optic).

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

The total impedance in the frequency range up to 100 MHz is 100 Ohm;

The amount of cross talk NEXT, depending on the signal frequency, should be at least 74 dB at a frequency of 150 kHz and at least 32 dB at a frequency of 100 MHz;

Attenuation ranges from 0.8 dB (at 64 kHz) to 22 dB (at 100 MHz);

The active resistance should not exceed 9.4 ohms per 100 m;

The cable capacity should not exceed 5.6 nF per 100 m.

All UTP cables, regardless of their category, are available in 4-pair design. Each of the four cable pairs has a specific color and pitch. Usually two pairs are for data transmission and two for voice transmission.

To connect cables to equipment, RJ-45 plugs and sockets are used, which are 8-pin connectors, similar to regular telephone connectors. RJ-11.

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

1.6 Choice of technologies

1.6.1 Ethernet technology. Ethernet access methods and frame formats

Consider how the above general approaches to solving the most important networking problems are embodied in the most popular network technology - Ethernet.

Networking technology is a consistent set of standard protocols and software and hardware that implements them (for example, network adapters, drivers, cables, and connectors) sufficient to build a computer network. The epithet "sufficient" underlines the fact that this set is the minimum set of tools with which you can build a workable network. Perhaps this network can be improved, for example, by allocating subnets in it, which will immediately require, in addition to the Ethernet standard protocols, the use of the IP protocol, as well as special communication devices - routers. The improved network will most likely be more reliable and faster, but at the expense of add-ons to the Ethernet technology that formed the basis of the network.

The term "network technology" is most often used in the narrow sense described above, but sometimes its extended interpretation is also used as any set of tools and rules for building a network, for example, "end-to-end routing technology", "technology for creating a secure channel", "IP technology. networks ".

The protocols on the basis of which a network of a certain technology (in the narrow sense) is built were specially developed for collaboration, so no additional effort is required from the network developer to organize their interaction. Sometimes network technologies are called basic technologies, meaning that on their basis the basis of any network is built. Examples of basic network technologies include, along with Ethernet, such well-known LAN technologies as Token Ring and FDDI, or X.25 and frame relay technologies for wide area networks. To get a workable network in this case, it is enough to purchase software and hardware related to one basic technology - network adapters with drivers, hubs, switches, cabling, etc. - and connect them in accordance with the requirements of the standard for this technology. The basic principle behind Ethernet is a random method of accessing shared media. Such media can be thick or thin coaxial cable, twisted pair, optical fiber or radio waves (by the way, the first network built on the principle of random access to a shared medium was the Aloha radio network of the University of Hawaii).

In the Ethernet standard, the topology of electrical connections is strictly fixed. Computers are connected to a shared environment according to a typical shared bus structure. Using a time-shared bus, any two computers can exchange data. Access control to the communication line is carried out by special controllers - Ethernet network adapters. Each computer, or more precisely, each network adapter, has a unique address. Data transfer 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. A computer on an Ethernet network can transmit data over the network only if the network is free, that is, if no other computer is currently exchanging data. Therefore, an important part of Ethernet technology is the procedure for determining the availability of the medium.

After the computer has made sure that the network is free, it starts transmitting, while "hijacking" the medium. The time of exclusive use of the shared medium by one node is limited by the transmission time of one frame. A frame is a unit of data that is exchanged between computers on an Ethernet network. The frame has a fixed format and, along with the data field, contains various service information, for example, the recipient's address and the sender's address.

The Ethernet network is designed in such a way that when a frame enters the shared data transmission medium, all network adapters simultaneously begin to receive this frame. They all analyze the destination address located in one of the initial fields of the frame, and if this address matches their own address, the frame is placed in the internal buffer of the network adapter. Thus, the destination computer receives the data intended for it. ...

Frame format

There are several Ethernet frame formats.

Initial Version I (no longer applicable).

Ethernet Version 2, or Ethernet Frame II, also called DIX, is the most common and still in use today. Often used directly by the Internet Protocol.

Figure 1.3 Ethernet Frame Format

Most common Ethernet II frame format

Novell is an internal modification of IEEE 802.3 without LLC (Logical Link Control).

IEEE 802.2 LLC frame.

IEEE 802.2 LLC / SNAP frame.

Some Hewlett-Packard Ethernet cards used an IEEE 802.12 frame that conforms to the 100VG-AnyLAN standard.

Optionally, an Ethernet frame can contain an IEEE 802.1Q tag to identify the VLAN to which it is addressed and an IEEE 802.1p tag to indicate priority.

Different frame types have different format and MTU value.

Based on this information, Ethernet technology was chosen for the local area network of the building, considered in the course work.

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

Everything the difference between Fast Ethernet technology and Ethernet is focused on the physical layer. The MAC and LLC layers in Fast Ethernet have remained exactly the same, and they are described in the previous chapters of the 802.3 and 802.2 standards. Therefore, considering Fast Ethernet technology, we will study only a few options for its physical layer.

The more complex structure of the physical layer of Fast Ethernet technology is due to the fact that it uses three options for cable systems:

Fiber optic multimode cable, two fibers are used; local area network cable

The coaxial cable, which gave the first Ethernet network, was not included in the number of allowed data transmission media of the new Fast Ethernet technology. This is a common trend in many new technologies, because over short distances, Category 5 twisted pair can transmit data at the same speed as coaxial cable, but the network is cheaper and easier to use. Over long distances, optical fiber has much higher bandwidth than coax, and the network cost is not much higher, especially when you consider the high troubleshooting costs of a large coaxial cabling system.

The figure below clearly shows the differences between Fast Ethernet and Ethernet technology from each other.

Figure 1.4.

Gigabit Ethernet.

The main idea of ​​the developers of Gigabit Ethernet was to preserve the ideas of the Ethernet technology as much as possible while reaching the speed of 1000 Mb / s, keeping all the Ethernet frame formats. There is still a half-duplex version of the protocol that supports the CSMA / CD access method. Keeping a low cost solution based on a shared environment allows Gigabit Ethernet to be used in small workgroups with fast servers and workstations. All major types of cables used by Ethernet in Fast Ethernet are supported: fiber-optic, twisted-pair category 5, unshielded twisted-pair.

10-Gigabit Ethernet.

The new 10 Gigabit Ethernet standard includes seven physical media standards for LAN, MAN and WAN. It is currently covered by the IEEE 802.3ae amendment and should be included in the next revision of the IEEE 802.3 standard.

10GBASE-CX4 - 10-Gigabit Ethernet technology for short distances (up to 15 meters) using CX4 copper cable and InfiniBand connectors.

10GBASE-SR is a 10 Gigabit Ethernet technology for short distances (up to 26 or 82 meters, depending on the cable type), using multimode fiber. It also supports distances up to 300 meters using new multimode fiber (2000 MHz / km).

10GBASE-LX4 - Uses wavelength division multiplexing to support distances from 240 to 300 meters over multimode fiber. Also supports distances up to 10 kilometers when using single mode fiber.

10GBASE-LR and 10GBASE-ER - these standards support distances up to 10 and 40 kilometers, respectively.

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

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

10GBASE-KR is a 10 Gigabit Ethernet technology for backplane / midplane of modular switches / routers and servers (Modular / Blade).

Harting announced the world's first tool-free 10 Gigabit RJ-45 connector, the HARTING RJ Industrial 10G.

1.6.3 Local networks based on shared media: TokenRing technology, FDDI technology

Shared environment - a method of organizing a network, in which a message from one workstation reaches all others using one common communication channel.

The algorithm for accessing the shared environment is the main factor that determines the efficiency of sharing the environment among the end nodes of the local network. It can be said that the access algorithm forms the "image" of the technology, allows to distinguish this technology from others.

Ethernet technology uses a very simple access algorithm that allows a host to transmit data at times when it thinks the shared medium is free. The simplicity of the access algorithm has determined the simplicity and low cost of Ethernet equipment. A negative attribute of the Ethernet access algorithm is collisions, that is, situations when frames transmitted by different stations collide with each other in a common environment. Collisions reduce the efficiency of the shared environment and make the network unpredictable.

The original version of Ethernet technology was designed for a coaxial cable, which was used by all nodes on the network as a common bus. The transition to twisted pair cabling and hubs has significantly improved the performance of Ethernet networks.

Token Ring and FDDI technologies supported more complex and efficient algorithms for accessing the medium, based on the transfer of a token to each other - a special frame that allows access. However, this advantage was not enough to survive in the competition with Ethernet.

Token Ring technology (802.5)

Token Ring networks, like Ethernet networks, are characterized by a shared data transmission medium, which in this case consists of lengths of cable connecting all the stations on the network in a ring. The ring is considered as a common shared resource, and access to it requires not a random algorithm, as in Ethernet networks, but a deterministic one, based on the transfer of the right to use the ring to stations in a certain order. This right is conveyed using a special format frame called a token or token.

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

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

To monitor the network, one of the stations acts as a so-called active monitor. The active monitor is selected during ring initialization as the station with the maximum 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 a failure of the active monitor, the latter in a healthy state generates a special frame of its presence every 3 seconds. If this frame does not appear on the network for more than 7 seconds, then the rest of the network stations begin the procedure for selecting a new active monitor.

FDDI

FDDI technology - Fiber Optic Distributed Data Interface - is the first local area network technology in which the data transmission medium is fiber optic cable. FDDI technology is largely based on Token Ring technology, developing and improving its basic ideas. The developers of the FDDI technology set the following goals as the highest priority:

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

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

Make the most of the potential network bandwidth for both asynchronous and synchronous (delay-sensitive) traffic.

The FDDI network is built on the basis of two fiber-optic rings, which form the main and backup data transmission paths between the network nodes. Having two rings is the primary way to improve resiliency in an FDDI network, and nodes that want to take advantage of this increased reliability potential must be connected to both rings.

In normal network operation, data passes through all nodes and all sections of the cable only on the Primary ring, this mode is called Thru mode - "through" or "transit". Secondary ring is not used in this mode.

In the event of some type of failure, where part of the primary ring cannot transmit data (for example, a cable break or node failure), the primary ring merges with the secondary ring again to form a single ring. This mode of operation of the network is called Wrap, that is, "folding" or "folding" rings. The folding operation is performed by means of hubs and / or FDDI network adapters. To simplify this procedure, data on the primary ring is always transmitted in one direction (in the diagrams this direction is shown counterclockwise), and along the secondary ring - in the opposite direction (shown in clockwise direction). Therefore, when a common ring of two rings is formed, the transmitters of the stations still remain connected to the receivers of neighboring stations, which makes it possible to correctly transmit and receive information by neighboring stations. ...

1.7 Review of Fast Ethernet Physical Media Specifications

802.3z Physical Media Specifications

The following physical media types are defined in the 802.3z standard:

Singlemode fiber optic cable;

Multimode fiber optic cable 62.5 / 125;

Multimode fiber optic cable 50/125;

Double coaxial with a characteristic impedance of 75 ohms.

Multimode cable

For data transmission over a multimode fiber-optic cable, traditional for computer networks, the standard defines the use of emitters operating at two wavelengths: 1300 and 850 nm. The use of LEDs with a wavelength of 850 nm is explained by the fact that they are much cheaper than LEDs operating at a wavelength of 1300 nm, although the maximum cable length is reduced, since the attenuation of multimode fiber at a wavelength of 850 m is more than twice as high as at wave of 1300 nm. However, the opportunity to reduce the cost is extremely important for a generally expensive technology like Gigabit Ethernet.

For multimode fiber, the 802.3z standard defines the l000Base-SX and l000Base-LX specifications.

In the first case, a wavelength of 850 nm is used (S stands for Short Wavelength, short wave), and in the second, 1300 nm (L stands for Long Wavelength, long wave).

For the l000Base-SX specification, the maximum length of the fiber-optic segment for the 62.5 / 125 cable is 220 m, and for the 50/125 cable - 500 m.Obviously, these maximum values ​​can be achieved only for full-duplex data transmission, since the time of a double signal turn on two sections 220 m is equal to 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 fiber segment values ​​should always be less than 100 m. The distances quoted of 220 and 500 m are based on the worst-case multimode cable bandwidth between 160 and 500 MHz / km. Real cables usually have significantly better performance, between 600 and 1000 MHz / km. In this case, the cable length can be increased to about 800 m.

Single mode cable

For the l000Base-LX specification, a 1300 nm semiconductor laser is always used as the light source.

The main area of ​​application of the l000Base-LX standard is single-mode fiber. The maximum cable length for single mode fiber is 5000 m.

The l000Base-LX specification can operate on multimode cable as well. In this case, the limiting distance turns out to be small - 550 m. This is due to the peculiarities of the propagation of coherent light in a wide channel of a multimode cable. A special adapter must be used to connect the laser transceiver to the multimode cable. ...

2. Creation of a project of a computer local network

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

1. Traffic of each class is isolated from others.

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

3. The distance from the connection point is: 1-87 meters; 2-74 meters; 3-74 meters.

4. The network is peer-to-peer with a speed of 100 Mb / s, without access to the Internet.

Project implementation cost

table 2

The cost of purchasing network equipment

Equipment	Characteristics	number
LAN 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

Workgroup Computers Configuration

Computer type	Work station
Motherboard	FM2 AMD A75 MSI FM2-A75MA-P33
CPU	AMD Athlon II X2 250
Video adapter	Built in MP
LAN card	10/100 / 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 = 352450

The total cost of the LAN project, excluding installation costs, was 548777 rubles.

Conclusion

In the course of the course work, practical and theoretical skills in designing a computer local network were obtained. During the course work, a local network of computer classes of the educational institution was created.

The recommendations of manufacturers of telecommunication equipment, the foundations of standards are investigated, the requirements for the system being created are determined and, as a result, a project of a local computer network (LAN) of a conventional enterprise is developed.

The course work presents the necessary calculations, drawings and diagrams, the specification of equipment and materials needed to build a LAN.

The total cost of hardware and software for the network was 196,327 rubles, and the cost of computer hardware was 352,450 rubles.

List of sources and literature

1. V.G. Olifer. ON THE. Olifer Computer networks, principles, technologies, protocols 4th edition 2010. - chapter 2 p. 55.3 p. 103.5 p. 139.

2. Peskova 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. Tanenbaum E., Weatherall D. Computer networks. 5th edition 2012

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

7. Maksimov N.V. Computer networks: Textbook [Text] / N.V. Maksimov, I.I. Popov - M .: FORUM: INFRA-M, 2005. - p. 109-111

8. Computer networks. Training course [Text] / Microsoft Corporation. Per. from English - M .: "Russian edition" LLP "Channel Trading Ltd.", 1998. -p. 258.

9. Craig Zucker Computer networks BHV-Petersburg, 2001 p. 7, 253, 234

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

11.www.ieeer8.org

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0

Course work

LAN Design in General Education High School

Introduction 3

1. Setting up a LAN at school 4
2. Design part 8

2.1 Selection and justification of the technology for constructing a LAN 8

2.2 Analysis of the data transmission medium 8

2.3 Network topology 8

2.4 Access Method 9

1. Selection and Justification of Network Hardware 10

3.1 Communication devices 10

3.2 Network equipment 13

3.3 Room layout 16

3.4 Calculation of the number of cables 19

1. Network installation instructions 22
2. Calculating the cost of equipment 30

Conclusion 31

References 33

Introduction

A local area network is a joint connection of several computers to a common data transmission channel, thanks to which the sharing of resources, such as databases, equipment, programs, is ensured. Using a local network, remote workstations are combined into a single system, which has the following advantages:

1. Sharing of resources - allows you to share resources, for example, peripheral devices (printers, scanners), all stations in the network.
2. Data sharing - allows you to share information located on the hard drives of workstations and the server.
3. Software Separation - Allows sharing of programs installed on workstations and the server.
4. Sharing processor resources - the ability to use computing power for data processing by other systems in the network.

The development of the local area network will be carried out in the building of the secondary school.

The purpose of this work is to calculate the technical characteristics of the network being developed, determine the hardware and software, the location of the network nodes, communication channels, and calculate the cost of implementing the network.

1. Setting up a LAN at school

In recent years, there has been a radical change in the role and place of personal computers and information technologies in the life of society. The modern period of the development of society is defined as the stage of informatization. Informatization of society presupposes a comprehensive and mass introduction of methods and means of collecting, analyzing, processing, transferring, archiving large volumes of information based on computer technology, as well as various data transmission devices, including telecommunication networks.

The concept of modernization of education, the project “Informatization of the education system” and, finally, technical progress set before education the task of forming ICT - a competent person capable of applying knowledge and skills in practical life for successful socialization in the modern world.

The process of school informatization involves the solution of the following tasks:

• development of pedagogical technologies for the use of informatization and communication tools at all levels of education;
• use of the Internet for educational purposes;
• creation and application of automation tools for psychological and pedagogical testing, diagnosing methods for monitoring and assessing the level of knowledge of students, their advancement in learning, establishing the level of the student's intellectual potential;
• automation of the activities of the school administration;
• training of personnel in the field of communication and information technologies.

A local network unites computers installed in one room (for example, a school computer class, consisting of 8-12 computers) or in one building (for example, in a school building several dozen computers installed in various subject rooms can be connected into a local network).

Local Area Network (LAN) is a computer network covering a relatively small area.

In small local networks, all computers are usually equal, that is, users independently decide which resources of their computer (disks, directories, files) to make public over the network. These are called peer-to-peer networks.

To increase the performance of a local network, as well as to ensure greater reliability when storing information on the network, some computers are specially allocated for storing files or application programs. These computers are called servers, and the local area network is called a server-based network.

A typical school LAN looks like this. There is one point of access to the Internet, to which the corresponding router (ADSL or Ethernet) is connected. The router is connected to a switch (switch) to which user PCs are already connected. A DHCP server is almost always activated on the router, which means that IP addresses are automatically distributed to all user PCs. Actually, this solution has both its pluses and minuses. On the one hand, the presence of a DHCP server simplifies the process of creating a network, since there is no need to manually make network settings on users' computers. On the other hand, in the absence of a system administrator, the situation is quite typical when no one knows the password to access the router, and the standard password has been changed. It would seem, why do you even need to "climb" into the router, if everything works like that? This is so, but there are unpleasant exceptions. For example, the number of computers in the school increased (another computer science class was equipped) and problems with conflicts of IP addresses on the network began. The fact is that it is not known what range of IP addresses is reserved on the router for distribution by the DHCP server, and it may well turn out that these same IP addresses are simply not enough. If such a problem occurs, then the only way to solve it without going into the settings of the router itself is to manually register all the network settings (IP address, subnet mask and gateway IP address) on each PC. Moreover, in order to avoid a conflict of IP addresses, this must be done on each PC. Otherwise, the manually assigned IP addresses may be out of the range reserved for distribution by the DHCP server, resulting in an IP address conflict over time.

Another problem is that all computers connected to the switch and, accordingly, having access to the Internet through a router, form one peer-to-peer local area network, or just a workgroup. This working group includes not only computers installed in the school computer class, but also all other computers in the school. These are the director's computer, the head teacher's computer, the secretaries' computers, the accounting computers (if there is one at the school), and all other computers with Internet access. Of course, it would be wise to split all these computers into groups and assign corresponding rights to each user group. But, as we have already noted, no domain controller is provided, and therefore it will simply not be possible to implement this. Of course, this problem could be partially solved at the hardware level by organizing several virtual local area networks (VLANs) and thereby physically separating student PCs from other computers. However, this requires a managed switch (or at least a Smart switch), which is very rare in a school. But even if there is such a switch, then you still need to be able to configure virtual networks. You can even not use virtual networks, but install an additional router and switch and apply different IP addressing (IP addresses from different subnets) for computers in the computer science class and all other computers. But again, this requires additional costs for the purchase of appropriate equipment and experience in configuring routers. Unfortunately, it is impossible to solve the problem of dividing school computers into isolated groups without additional financial costs (the presence of a controlled switch in the school is an exception to the rule). At the same time, such a division is not mandatory. If we consider the need for such a separation from the point of view of network security, then the problem of the safety of computers of teachers and administration from encroachments from students can be solved in another way.

1. Design part

2.1 Selection and justification of the technology for building a LAN.

The main purpose of the projected computer network is to provide communication between network computers and provide the ability to transfer files at speeds up to 100 Mbit / s. Thus, to build a LAN for all departments of the building, Fast Ethernet technology will be used.

Technologies for building a LAN. In this work, to build a network, Fast Ethernet technology will be used, providing a data transfer rate of 100 Mbit / s. Also, the topology "star-yes" will be applied using unshielded twisted pair CAT5 as communication lines.

2.2 Analysis of the data transmission medium.

For data transmission in Fast Ethernet, the 100 Base-TX standard will be used. A 4-pair CAT5 cable is used. All pairs are involved in data transfer. Parameters:

 data transfer rate: 100 Mbps;

 type of cable used: unshielded twisted pair CAT5;

 maximum segment length: 100 m.

2.3 Network topology.

The topology of a network is determined by the placement of nodes in the network and the connections between them. The term "network topology" refers to the path that data travels in a network. For Fast Ethernet technology, a star topology will be used.

To build a network with a star architecture, a hub (switch) must be placed in the center of the network. Its main function is to provide communication between computers on the network. That is, all computers, including the file server, do not communicate directly with each other, but join the hub. Such a structure is more reliable, since in the event of failure of one of the workstations, all the others remain operational. The star topology is the fastest of all computer network topologies, since data transmission between workstations passes through the central site (with good performance) on separate lines that are used only by these workstations. The frequency of requests for information transfer from one station to another is low compared to that achieved in other topologies.

2.4 Access method.

Fast Ethernet networks use the CSMA / CD access method. The basic concept of this method is as follows:

All stations listen to transmissions on the channel, determining the state of the channel;

Carrier check;

The start of transmission is possible only after the detection of a free state of the channel;

The station monitors its transmission, when a collision (collision) is detected, the transmission stops and the station generates a collision signal;

The transmission is resumed after a random period of time, the duration of which is determined by a special algorithm, if the channel is free at that moment;

Several unsuccessful transmission attempts are interpreted by the station as a network failure.

Even in the case of CSMA / CD, a collision situation may arise when two or more stations simultaneously determine a free channel and start trying to transmit data.

1. Selection and justification of network hardware

3.1 Communication devices

Selecting a network adapter.

A network adapter is a computer peripheral device that
directly interacting with the data transmission medium, which
directly or through other communication equipment connects it with
other computers. This device solves the problem of reliable exchange
binary data, represented by corresponding electromagnetic signals, over external communication lines. The network adapter is connected via the PCI bus to the motherboard.

The network adapter usually performs the following functions:

• registration of the transmitted information in the form of a frame of a certain format.
• gaining access to the data transmission medium.
• coding a sequence of bits of a frame with a sequence of electrical signals when transmitting data and decoding when receiving them.
• converting information from parallel to serial and vice versa.
• synchronization of bits, bytes and frames.

TrendNet TE 100-PCIWN network cards are selected as network adapters.

Choosing a hub (switch).

A hub (repeater) is the central part of a computer network in the case of a star topology.

The main function of a hub is to repeat the signals arriving at its port. The repeater improves the electrical characteristics of the signals and their synchronization, and due to this it becomes possible to increase the total cable length between the most distant nodes on the network.

A multiport repeater is often called a hub or hub, which reflects the fact that this device implements not only the function of repeating signals, but also concentrates the functions of connecting computers to a network in one central device.

The lengths of cable that connect two computers or any other two network devices are called physical segments, so the hubs and repeaters that are used to add new physical segments are a means of physically structuring the network.

A concentrator is a device in which the total bandwidth of the input channels is higher than the bandwidth of the output channel. Since the input data streams in the concentrator are larger than the output stream, its main task is to concentrate the data.

The concentrator is an active piece of equipment. The hub serves as the hub (bus) of the star network configuration and connects the network devices. In a hub, a separate port must be provided for each node (PCs, printers, access servers, telephones, etc.).

Switches.

Switches monitor and control network traffic by analyzing the destination addresses of each packet. The switch knows which devices are connected to its ports and routes packets only to the required ports. This makes it possible to simultaneously work with several ports, thereby expanding the bandwidth.

Thus, switching reduces the amount of unnecessary traffic, which occurs when the same information is transmitted to all ports,

Switches and hubs are often used on the same network; hubs expand the network by increasing the number of ports, and switches break the network into smaller, less congested segments. However, the use of a switch is justified only in large networks, since its cost is an order of magnitude higher than the cost of a hub.

The switch should be used in the case of building networks, the number of workstations in which is more than 50, to which our case can also be attributed, as a result of which we choose D-Link DES-1024D / E, 24-port Switch 10 / 100Mbps switches.

3.2 Network equipment

Choice of cable type.

Today, the vast majority of computer networks use wires or cables as a transmission medium. There are various types of cables to suit the needs of all kinds of networks from large to small.

Most networks use only three main groups of cables:

• coaxial cable;
• twisted pair:

* unshielded; o * shielded;

Fiber optic cable, single mode, multimode (fiber
optic).

Today, the most common type of cable and the most suitable for its characteristics is twisted pair. Let's dwell on it in more detail.

A twisted pair cable is a cable in which an insulated pair of conductors is twisted with a few turns per unit length. Twisting the wires reduces external electrical noise when signals propagate through the cable, and shielded twisted pairs further increase the signal immunity.

Twisted pair cable is used in many networking technologies, including Ethernet, ARCNet, and IBM Token Ring.

Twisted pair cables are divided into: unshielded (UTP - Unshielded Twisted Pair) and shielded copper cables. The latter are divided into two types: with the shielding of each pair and a common screen (STP - Shielded Twisted Pair) and with only one common screen (FTP - Foiled Twisted Pair). The presence or absence of a shield on a cable does not at all mean the presence or absence of protection of the transmitted data, but only indicates various approaches to suppressing interference. The absence of a shield makes unshielded cables more flexible and more kink resistant. In addition, they do not require an expensive ground loop to operate normally as shielded ones. Unshielded cables are ideal for indoor installation in offices, while shielded cables are best used for installation in places with special operating conditions, for example, near very strong sources of electromagnetic radiation, which are not usually found in offices.

Because of Fast Ethernet 100Base-T and star topology, it is suggested to choose Category 5 unshielded twisted pair (UTP) cable.

Choice of connectors.

To connect workstations and the switch, RJ-45 connectors, 8-pin sockets, the cable of which is crimped in a special way, are selected.

When a computer is used to exchange information by telephone
network, you need a device that can receive a signal from a telephone
network and convert it to digital information. This device
called a modem (modulator-demodulator). The purpose of the modem is to replace the signal coming from the computer (a combination of zeros and ones) with an electrical signal with a frequency corresponding to the operating range of the telephone line.

There are internal and external modems. Internal modems are made in the form of an expansion card inserted into a special expansion slot on the computer motherboard. An external modem, unlike an internal one, is designed as a separate device, i.e. in a separate case and with its own power supply when the internal modem receives electricity from the computer's power supply.

Internal modem Advantages

1. All internal models without exception (as opposed to external ones) have a built-in FIFO. (First Input First Output - first in, first out). FIFO is a data buffering chip. An ordinary modem, when passing a data byte through the port, each time requests interrupts from the computer. The computer on special IRQ lines interrupts the modem for a while, and then resumes it again. This slows down your computer as a whole. FIFO allows you to use interrupts several times less often. This is of great importance when working in multi-tasking environments. Such as Windows95, OS / 2, Windows NT, UNIX and others.
2. Using an internal modem reduces the number of wires pulled in the most unexpected places. Also, the internal modem does not occupy the desktop.
3. Internal modems are the serial port on the computer and do not occupy the existing ports on the computer.
4. Internal models of modems are always cheaper than external ones.
   disadvantages
5. They occupy an expansion slot on the computer motherboard. This is very inconvenient on multimedia machines with a large number of add-on cards installed, as well as on computers that run servers on networks.
6. There are no indicator lights, which, with a certain skill, allow you to monitor the processes taking place in the modem.
7. If the modem hangs, then it can be restored only by pressing the "RESET" button to restart the computer.

External modems Advantages

1. They do not occupy an expansion slot, and if necessary, they can be easily disconnected and transferred to another computer.
2. There are indicators on the front panel that help you understand what operation the modem is currently performing.
3. When the modem hangs, you do not need to restart the computer, just turn off and on the power of the modem.

disadvantages

1. Requires a multicard with built-in FIFO. Without FIFO, the modem will certainly work, but the data transfer rate will drop.
2. An external modem takes up the desktop and requires additional wires to connect. This also creates some inconvenience.
3. It occupies the serial port of the computer.
4. An external modem is always more expensive than a similar internal modem. includes a housing with indicator lights and a power supply.

For our network, we will choose the ZyXEL Omni 56K internal modem. V.90 (PCTel) int PCI.

3.3 Layout of premises

All diagrams have the following symbols:

CB - server.

РС - workstation.

K - switch.

Fig. one Ground floor network diagram

Fig. 2 Network diagram on the second floor

Fig. 3 Network diagram on the 3rd floor

3.4 Calculation of the amount of cable

The calculation of the total length of the cable by floors, required to build a local network, is given in tables 1, 2, 3. The cable is laid along the walls in special boxes.

Table 1. Cable length on the 1st floor.

K1-K2 16 meters

K1-K3 14 meters

The total cable length on the ground floor is 96 meters.

Table 2. Cable length on the 2nd floor

Work station	Length of cable From PC to K

Length of cable between switches:

K4K5 17 meters

The length of the cable from the server to K 4 - 1 meter

The total cable length on the second floor is 156 meters.

Table 3. Cable length on the 3rd floor

Work station	Cable length from РС to К

Length of cable between switches:

К7К6 17 meters

K7K8 15 meters

The total cable length in segment C is 230 meters.

The length of the cable between floors is 2 meters

The total cable length of the entire local network, taking into account the safety factor, is (96 + 156 + 230 + 2 + 2) * 1.2 = 583.2 m.

1. Network installation instructions

At the beginning of the development of local networks, coaxial cable was the most widespread transmission medium. It was and is used primarily in Ethernet networks and partly ARCnet. A distinction is made between "thick" and "thin" cables.

Thick Ethernet is typically used as follows. It is laid along the perimeter of a room or building, and 50-ohm terminators are installed at its ends. Due to its thickness and rigidity, the cable cannot connect directly to the network board. Therefore, "vampires" are installed on the cable in the right places - special devices that pierce the cable sheath and connect to its braid and central core. "Vampire" sits so firmly on the cable that after installation it is impossible to remove it without a special tool. To the "vampire", in turn, is connected a transceiver - a device that matches the network card and cable. Finally, a flexible cable with 15-pin connectors on both ends is connected to the transceiver - the other end connects to the AUI (attachment unit interface) connector on the network card.

All these difficulties were justified by only one thing - the permissible maximum length of a "thick" coaxial cable is 500 meters. Accordingly, one such cable can serve a much larger area than a "thin" cable, the maximum allowable length of which is, as is known, 185 meters. With some imagination, you can imagine that a "thick" coaxial cable is an Ethernet hub distributed in space, only completely passive and does not require power. It has no other advantages, but there are more than enough disadvantages - first of all, the high cost of the cable itself (about $ 2.5 per meter), the need to use special devices for installation ($ 25-30 per piece), the inconvenience of laying, etc. ... This gradually led to the fact that "fat Ethernet" slowly but surely left the scene, and is currently used in very few places.

Thin Ethernet is far more widespread than its fat cousin. The principle of use is the same, but due to the flexibility of the cable, it can be connected directly to the network card. To connect the cable, BNC (bayonet nut connector) connectors are used, which are installed on the cable itself, and T-connectors, which serve to drain the signal from the cable to the network card. BNC connectors are crimp and collapsible (an example of a collapsible connector is the domestic connector SR-50-74F).

T-connector

To mount the connector to the cable, you will need either a special crimping tool or a soldering iron and pliers.

The cable must be prepared as follows:

1. Cut carefully so that the end is straight. Slide the metal sleeve (piece of tubing) that comes with the BNC connector over the cable.
2. Remove the outer plastic sheath from the cable approximately 20 mm. Be careful not to damage any of the braiding conductors if possible.
3. Unbraid the braid carefully and spread apart. Strip the insulation from the center conductor approximately 5 mm.
4. Install the center conductor into the pin also supplied with the BNC connector. Using a special tool, crimp the pin securely to fix the conductor in it, or solder the conductor into the pin. When soldering, be especially careful and attentive - poor soldering after a while will cause network failures, and it will be quite difficult to localize this place.
5. Insert the center conductor with the pin installed on it into the connector body until it clicks into place. A click means that the pin sits into place in the connector and locks into place.
6. Spread the braid conductors evenly over the surface of the connector, if necessary, cut to length. Slide the metal sleeve over the connector.
7. Use a special tool (or pliers) to gently crimp the sleeve until the braid contacts the connector securely. Do not crimp too hard - you could damage the connector or pinch the insulation of the center conductor. The latter can lead to unstable operation of the entire network. But it is also impossible to crimp it too weakly - poor contact of the cable braid with the connector will also lead to malfunctions.

Note that the domestic SR-50 connector is mounted in about the same way, except that the braid in it is embedded in a special split sleeve and secured with a nut. In some cases, this may be even more convenient.

Twisted Pair Cables

Twisted pair (UTP / STP, unshielded / shielded twisted pair) is currently the most common medium for signal transmission in local area networks. UTP / STP cables are used in Ethernet, Token Ring and ARCnet networks. They differ by category (depending on the bandwidth) and the type of conductor (flexible or solid). In a cable of the 5th category, as a rule, there are eight conductors twisted in pairs (that is, four pairs).

UTP cable

Category 5 twisted pair structured cabling is very flexible in use. Its idea is as follows.

At least two (three are recommended) four-pair RJ-45 sockets are installed on each workplace. Each of them is connected with a separate cable of the 5th category to a cross-section or patch panel installed in a special room - a server room. Cables are brought into this room from all workplaces, as well as city telephone inputs, dedicated lines for connecting to global networks, etc. In the room, of course, servers are mounted, as well as office PBX, alarm systems and other communication equipment.

Due to the fact that the cables from all workplaces are brought into a common panel, any outlet can be used both to connect the workplace to a LAN, and for telephony, or anything at all. Let's say two outlets in the workplace were connected to a computer and a printer, and the third to a telephone exchange. In the process of work, it became necessary to remove the printer from the workplace and install a second phone instead. There is nothing simpler - the patch cord of the corresponding outlet is disconnected from the hub and switched to a dial-up switch, which will take the network administrator no more than a few minutes.

2-port socket

A patch panel, or connection panel, is a group of RJ-45 outlets mounted on a 19-inch plate. This is the standard size for universal communication racks in which equipment is installed (hubs, servers, uninterruptible power supplies, etc.). On the reverse side of the panel, there are connectors, into which the cables are mounted.

The cross, in contrast to the patch panel, does not have sockets. Instead, it carries special connection modules. In this case, its advantage over the patch panel is that, when used in telephony, the inputs can be interconnected not with special patch cords, but with ordinary wires. In addition, the crossbar can be mounted directly on the wall - it does not require a communication cabinet. Indeed, there is no point in purchasing an expensive communications cabinet if your entire network consists of one or two dozen computers and a server.

Cables with stranded flexible conductors are used as patch cords, that is, connecting cables between the socket and the network board, or between the sockets on the connection panel or distribution frame. Cables with solid conductors - for laying the actual cable system. The installation of connectors and sockets on these cables is completely identical, but usually cables with solid conductors are mounted on the sockets of user workstations, connection panels and cross-sections, and the connectors are installed on flexible connecting cables.

Patch panel

Typically, the following types of connectors are used:

• S110 - the general name of connectors for connecting a cable to a universal distribution frame "110" or switching between inputs on a distribution frame;
• RJ-11 and RJ-12 are six-pin connectors. The former are usually used in general-purpose telephony - you can find such a connector on the cords of imported telephones. The second is usually used in telephones designed to work with office mini-automatic telephone exchanges, as well as to connect a cable to ARCnet network cards;
• RJ-45 is an eight-pin connector typically used to connect a cable to Ethernet network cards or for patch panel connections.

RJ-45 connector

Depending on what you need to connect with, different patch cords are used: "45-45" (on each side on the RJ-45 connector), "110-45" (on the one side S110, on the other - RJ-45 ) or "110-110".

For the installation of RJ-11, RJ-12 and RJ-45 connectors, special crimping devices are used, which differ in the number of knives (6 or 8) and the size of the socket for fixing the connector. As an example, consider installing a Category 5 cable on an RJ-45 connector.

1. Cut the end of the cable carefully. The end of the cable must be flat.
2. Using a special tool, remove the outer insulation from the cable to a length of about 30 mm and cut the thread embedded in the cable (the thread is intended for easy stripping of the cable for a longer length). Any damage (cuts) of the conductor insulation is absolutely unacceptable - that is why it is advisable to use a special tool, the cutter blade of which protrudes exactly to the thickness of the outer insulation.
3. Carefully spread, untwist and align the conductors. Align them in one row, while observing the color coding. There are two most common color pairing standards: T568A (recommended by Siemon) and T568B (recommended by ATT and in fact the most commonly used).

On an RJ-45 connector, the wire colors are arranged as follows:

Conductors should be located strictly in one row, without overlapping each other. Holding them with one hand, cut the conductors evenly with the other so that they protrude 8-10 mm above the outer winding.

1. Holding the connector with the tab downward, insert the cable into the connector. Each conductor must fall into place in the connector and abut against the limiter. Before crimping the connector, make sure you are not mistaken in the wire routing. In case of incorrect wiring, in addition to the lack of correspondence with the numbers of the contacts at the ends of the cable, which can be easily identified with the help of a simple tester, a more unpleasant thing is possible - the appearance of "splitted pairs".

To detect this defect, an ordinary tester is not enough, since the electrical contact between the corresponding contacts at the ends of the cable is provided and everything seems to be normal in appearance. But such a cable will never be able to provide normal connection quality even in a 10-megabit network over a distance of more than 40-50 meters. Therefore, you need to be careful and take your time, especially if you do not have enough experience.

1. Insert the connector into the socket on the crimper and crimp it against the stop on the crimper. This locks the retainer on the connector into place, keeping the cable steady in the connector. The contact blades of the connector will each cut into its own conductor, ensuring reliable contact.

Similarly, you can install the RJ-11 and RJ-12 connectors using the appropriate tool.

No special crimping tool is required to mount the S110 connector. The connector itself is supplied unassembled. By the way, unlike "disposable" RJ connectors, the S110 connector allows multiple disassembly and assembly, which is very convenient. The sequence of actions during installation is as follows:

1. Strip the outer insulation of the cable to a length of about 40 mm, separate the pairs of conductors to the sides without unraveling them.
2. Secure the cable (in the half of the connector that does not have a terminal block) with a plastic tie and cut off the resulting "tail".
3. Tuck each wire neatly into the organizer on the connector. Do not untwist the pair too much, as this will degrade the performance of the entire cable connection. The sequence of laying pairs is usual - blue-orange-green-brown; in this case, the light wire of each pair is laid first.
4. Use a sharp tool (side cutter or knife) to cut each conductor along the edge of the connector.
5. Replace the other half of the connector and squeeze it with your hands until all latches snap into place. In this case, the knives of the contact group will cut into the conductors, providing contact.

Fiber optic cable

Fiber optic cables are the most promising and fastest-performing signal propagation medium for local networks and telephony. In local area networks, fiber optic cables are used to work with ATM and FDDI protocols.

Connector stripper and crimp tool

Optical fiber, as its name implies, transmits signals using pulses of light radiation. Semiconductor lasers and LEDs are used as light sources. Fiber optic is classified into single mode and multimode.

Singlemode fiber is very thin, with a diameter of about 10 microns. Due to this, a light pulse passing through the fiber is less often reflected from its inner surface, which provides less attenuation. Consequently, single-mode fiber provides longer range without the use of repeaters. The theoretical bandwidth of single-mode fiber is 10 Gbps. Its main disadvantages are high cost and high complexity of installation. Single-mode fiber is used primarily in telephony.

Multimode fiber has a larger diameter of 50 or 62.5 microns. This type of fiber is most commonly used in computer networks. The greater attenuation in multimode fiber is due to the higher dispersion of light in it, due to which its bandwidth is significantly lower - theoretically it is 2.5 Gbit / s.

To connect an optical cable with active equipment, special connectors are used. The most common connectors are SC and ST.

Mounting connectors on a fiber optic cable is a very demanding operation that requires experience and special training, so you should not do this at home without being a specialist.

1. Calculating the cost of equipment

The cost of the components is shown in table 4 (according to the M-video online store in Balakovo).

Table 4 equipment cost

The table shows that the network design costs do not exceed reasonable limits.

1. Network development prospects

The LAN presented in this paper can be developed and expanded. At this stage, the following measures can be taken to improve the local network:

Connection of an additional network segment on the second and third floors;

Connection of additional workstations at any part of the network;

Installation of managed switches in the most loaded network segments (directly in computer classes);

Unloading the most loaded network segments by splitting it into branches;

Software updates to improve network quality.

Conclusion

In the course of the work, a local computer network was developed, consisting of 38 workstations and 1 server based on Fast Ethernet technology, the most widespread type of network at the present time, the advantages of which include ease of setup, low cost of components. The star topology used in the design provides the ability to centrally manage the network and makes it easy to find a failed node. The network is built with future development in mind. Windows Server 2003 R2 was selected as the server operating system. The required amount of network equipment is calculated, its price is given data and calculations of the equipment used, the construction costs are 66,539 rubles. A detailed network plan has been drawn up, where all the characteristics of the components used are indicated. The design tasks have generally been completed. The work has all the necessary data and calculations to build a network.

Bibliography

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4. Brezgunova, I.V. Hardware and software of a personal computer. Operating system Microsoft Windows XP / - M: RIVSH, 2011 .-- 164 p.
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Download: You do not have access to download files from our server.

The bundles of wires hanging from the walls in the corridors of public buildings have sunk into summer. Now communications are laid in a hidden way, in boxes, trays behind false ceilings, through switching floor cabinets to the centers of server equipment. All terminal devices-sockets are tightly fixed in their places, in walls or boxes, marked and numbered, the networks themselves have become local, performing a specialized role among a separate group of information devices.

How local networks are built

Modern networks are convenient to use, nothing "leaves" in them, they can easily integrate various even new applications and change the purpose. The cable infrastructure itself, or local area network (LAN), serves for many years, for example, changing active equipment, which becomes obsolete much faster, you can easily increase bandwidth without serious investment and capital expenditures. All this is preceded by the design of local area networks, which determines the type and purpose of future local area networks. They arrange a LAN not only for a group of computers united by one task, but also for local or separate applications. There are a lot of purposes for which the construction of a LAN is done and a correctly formulated technical task (TOR) will help the designer to embody all the wishes of the customer. The LAN design should describe the infrastructure to be created very clearly and in detail. Detailed floor plans indicate the location of terminal devices, computer outlets, their purpose, numbering and marking, cross-connection diagrams, model and brand. During the construction of a LAN, various materials and equipment from different or from a specific manufacturer can be used, the choice of these elements and systems is also determined by the LAN project.

But not everything is as easy and simple as it seems at first glance, there are certain risks. For example, the terms of reference (TOR) should be an integral part of the contract for design and survey work. The design company must have many years of experience in this area, have the necessary licenses, certificates and approvals, that is, be verified and professional. A very large number of amateur enthusiasts undertake work not only without design, without preliminary studies of the object, but also without pre-agreed schemes, plans and work schedule. This results in additional work, an increase in deadlines, dirt and noise in the office, the lack of a clear understanding of the needs of the customer.

The cost of designing a LAN is negligible compared to the consequences of eliminating improperly performed work, improperly laid or completely inappropriate cable.

Capital investments made once in cable infrastructure, in particular in a LAN device, will be repaid many times over in the first year if you chose the right path: you turned to a specialized company, for example, to us, EngineeringGroup LLC. We will be able to reduce the budget and time of the Customer already at the stage of creating the technical assignment, we will come to inspect the object (travel around the Moscow region is free), we will help you correctly formulate the technical specification and tell you about innovations and innovations in this area.

Having ordered and received a competent LAN project, you can bring it to life with the help of any professional installation company. But if you order from us and the execution of work, we will be able to return part of the money (up to 30%) spent in the design.