LAN is a network designed to process the storage and transmission of data and is a cable system of a building object or a group of building objects. LANs are used to solve problems such as: Distribution of data. In this regard, it is not necessary to have drives for storing the same information at each workplace; Resource allocation. Peripherals can be accessed by all LAN users.

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COURSE WORK

Made by a student of group 1ISz-410

group

directions of training (specialty)

230400.62. Information systems and technologies

code, name

Belov Nikita Sergeevich

Full Name

Supervisor

Selyanichev Oleg Leonidovich

Full Name

Associate Professor, Ph.D.

Job title

Date of submission of work

« »

Conclusion on admission to protection

Grade _______________, _______________

number of points

Teacher's signature_________________

Cherepovets, 2015

Introduction

Currently, local area networks are widely used in enterprises and institutions.

LAN is a network designed for processing, storing and transmitting data, and is a cable system of an object (building) or a group of objects (buildings).

The main purpose of these networks is to provide access to network-wide (information, software and hardware) resources. In addition, LANs allow employees of enterprises to quickly exchange information with each other.

LANs are used to solve problems such as:

Data distribution. Data in the local network is stored on the central PC and can be accessed at workstations. In this regard, it is not necessary to have drives for storing the same information at each workplace;
Resource allocation. Peripherals can be accessed by all LAN users. Such devices can be, for example, a scanner or laser printer;
Distribution of programs. All LAN users can share access to programs that have been centrally installed on one of the computers.

The basis for designing a LAN is the taskfor coursework in the discipline"Information and computer networks". Namely, select equipment, data transfer protocols and indicate recommendations for setting up software for the BelovTansAvto IE organization.

Tasks solved by the organization

IP "BelovTansAvto" transport company engaged in cargo transportation in the city of Vologda and beyond.

Within this term paper it is necessary to design a local network for the IP "BelovTansAvto". Each employee's workplace is equipped with a personal computer, which, in turn, must be combined into a local network for data exchange with each other. In addition, the office is equipped with printing devices, which must be accessed from each PC through this network.

Organization space planning

The office space consists of three workplaces, as well as a utility room. In total there are 3 computers and 1 printing device. The floor plan is shown below.

Floor plan

Selection of equipment parameters

To choose the right office computer of the whole variety of options offered, first of all, we will limit the range of tasks that will have to be solved with its help.

Without a doubt, in the first place here is the software package of the same name from Microsoft , working, of course, under the operating system of the same company. In most cases, this includes e-mail programs and browsers.

Further, everything depends on the specialization of the company and the imagination of those responsible for choosing the software. In the general case, the matter is limited not to the newest, but to proven and stable versions packages for working with text, graphics, electronic drawings and diagrams, databases, audio, video materials, etc.

This organization works with the software package from Microsoft.

Let's make a configuration PC for staff:

Motherboard	ASUS M5A78L-M / USB3 (RTL) SocketAM3+< AMD 760G >PCI-E+SVGA+DVI+HDMI GbLAN SATA RAID MicroATX 4DDR-III	2550
CPU	AMD FX-4300 (FD4300W) 3.8 GHz / 4core / 4+4Mb / 95W / 5200 MHz Socket AM3+	3400
CPU cooler	DEEPCOOL GAMMAXX 200, 92mm
HDD	1 Tb SATA 6Gb/s Seagate Barracuda< ST1000DM003 >3.5" 7200rpm 64Mb	2690
RAM	Kingston ValueRAM< KVR1333D3N9 / 4G>DDR-III DIMM 4Gb< PC3-10600>CL9	1950
Frame	cooler master< RC-350-KKN1-GP >CMP350 Black&Black ATX Without PSU	1920
power unit	FSP/SPI 450W ATX (24+4+6pin)	1420
D VD drive	DVD RAM & DVD±R/RW & CDRW LG GH22LS50 SATA

When choosing a server computer, consider the following characteristics:

processor performance;
amount of RAM;
speed and hard drive capacity.

You must also select software for the server and workstations. Licensed copies of the OS are already installed on workstations Microsoft Windows 7 and Windows 8, and we will choose the operating system for the server based on compatibility with these systems.

All invoices, reports, reports and more are done using the printer. When buying an MFP, printer, scanner, etc., you should buy it with a built-in "print server", that is, with a built-in network card. This will eliminate the purchase of an external print server and the cost of additional configuration.

An example of a printing device. Kyocera FS-6525MFP

Characteristics:

Printer/scanner/copier/fax device

Print type black and white

Laser printing technology

Desktop placement

Interfaces Ethernet (RJ-45), USB 2.0

Price: 42 860

network hardware

Network equipment devices necessary for the operation of a computer network, for example: router, switch, hub. Let us describe the equipment that will be used in this organization.

Despite the intensive development of wireless technologies, cable data transmission lines still remain the most reliable, noise-proof, and relatively inexpensive solution for organizing scalable computer networks with access control. The choice of twisted pair in the design and installation of such networks is one of the main tasks.

The parameters of a twisted pair that must be considered in the design are as follows:

Category . According to the standards of telecommunication cable networks EIA / TIA 568, and ISO 11801 there are ten of them: categories 1-4 do not meet modern requirements, and are not currently used, and categories 7 and 7a are inferior in expediency to optical cable. Therefore, we will focus on categories 5, 5e, 6, 6a.
Core material . Copper or copper plated aluminium. Plus, you should pay attention to the technology of copper plating: CCA, CCAA, CCAG, or CCAH
Outer shell type:for external or internal laying
Shield Type:for laying near strong sources of electromagnetic radiation
The presence of a cable or armorfor aerial laying, or laying in a room infested with rodents

An unprotected twisted pair cable is used to connect computers.(UTP Unshielded twisted pair) category 5e. Category 5e cable is the most common and is used to build computer networks.

Cost: 50 (meters) * 15 (rubles per meter) = 750 rubles.

A switch will be used to connect computers to a single local network.. Its main advantage is that in the course of its work it forms a switching table by typing a list of MAC addresses, and according to it, data is forwarded. Each switch, after a short period of time, "knows" which port each computer on the network is on.

NETGEAR FS116GE Switch

Switch characteristics.

Switch TP-LINK TL-SG1016D 16-Port Gigabit Switch

Number of portsswitch 16 x Ethernet 10/100 Mbps

Internal bandwidth 32 Gbps

Number of slots for additional interfaces n/a

Management no data

Support for Auto MDI/MDIX standards

Dynamic Routing Protocols n/a

Dimensions 286 x 27 x 103 mm

Price: 3 070 rub.

Lenovo ThinkServer TS140 70A4S00400 was chosen as the server.

Lenovo ThinkServer TS140 This is an off-the-shelf server from IBM that is of high quality, excellent performance and good scalability. Target audience growing companies that need the ability to further upgrade the server. The System x3100 series supports high performance Intel E3 series processors. The server is optimized for rapid deployment and subsequent monitoring of work. The performance of this model (2582-K9G) is provided by the Intel E3-1225 v3 processor with optimized work with multi-threaded applications. Preinstalled RAM 4GB (using high performance DDR3 ECC). The server has a Micro ATX Tower (4U) form factor and is designed for outdoor installation. As the need for performance grows, the configuration may change.

Lenovo ThinkServer TS140

Server characteristics.

Characteristics:

Main

Manufacturer Lenovo

Chassis Form Factor MicroATX Tower

CPU

Processor manufacturer Intel

Xeon line

Clock frequency 3000 MHz

Number of cores 4

Processor model E3-1225V3

Number of installed processors 1

Maximum number of processors 1

RAM

The amount of installed memory 4096 MB

Memory type DDR-3

Number of slots 4

HDD

SATA interface

Number of drives installed 2

The amount of installed HDD 500 GB

HDD Form Factor 3.5"

Maximum number of HDDs 4

Drive unit

Optical drive Yes

Net

Network interface Gigabit Ethernet (10/100/1000 Mbps)

Power supply 280 W

Price: 48 190 rubles.

Also, for the possibility of accessing the Internet will be usedwifi router. TP-LINK TL-WR841HP very fast router. The manufacturer claims a maximum data transfer rate of 750 Mbps. One of the important advantages of this model over many others is the ability to simultaneously use two frequency bands: 2.4 and 5 GHz. Thanks to this, users can simultaneously connect to the Internet from phones, smartphones, and from a laptop, PC or tablet. Another plus of this model is that it comes with sufficiently powerful antennas that allow you to distribute the Internet via Wi-Fi for more than 200 m.

wifi routerTP-LINK 4*LAN WAN10/100M Atheros

Router characteristics.

Type: wifi hotspot

Interface: 4 x Fast Ethernet 10/100 Mbps

1 x WAN

VPN support: yes

Network features Secure VPN protocols: PPTP,

PPPoE, L2TP, IPSec
Obtaining an IP address: Static IP, Dynamic IP
QoS: Supported

WMM (Wi-Fi Multimedia) support:

Supported
Virtual Server: Supported
WPS (Wi-Fi Protected Setup):

Supported
DMZ Supported
NAT: Supported, Port Triggering
DHCP Server: Supported

output power

Wireless network 20 dBm

Wireless frequency 2.4 / 5 GHz

Management: web interface

Dimensions 225x33x140 mm

Features Firewall: SPI (Stateful Packet Inspection), DOS Attack Protection, Timed Access Control, Parental Control, IP Filtering, MAC Address Filtering, Domain Filtering
Data security schemes: WPA2-PSK; WPA-PSK; WPA2; WPA WEP encryption with 64-bit or 128-bit key

Price: 4,350 RUB

Logical, block diagram of the network

The structure (topology) of a computer network is usually understood as the physical location of network computers one relative to one and the way they are connected by communication lines.

There are three main network topologies:

1. Bus network topology(bus), in which all computers are connected in parallel to one communication line and information from each computer is simultaneously transmitted to all other computers;

2. Network topology star(star), in which other peripheral computers are connected to one central computer, each of them using its own separate communication line;

3. Network topology ring(ring), in which each computer always transmits information to only one computer, the next in the chain, and receives information only from the previous computer in the chain, and this chain is closed in a "ring".

Bus network topology

Network topology "star"

Network topology "ring"

In practice, combinations of the basic topology are often used, but most networks are focused on these three.

When designing a network for this organization, we will use the Star topology. Star Topologyis the fastest of all computer network topologies, since data transmission between workstations passes through the central node (with its good performance) over separate lines 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. Network throughput is determined by the computing power of the node and is guaranteed for each workstation. Collisions (collisions) of data do not occur.

The cable connection is quite simple as each workstation is connected to a node.

The central control node file server implements an optimal protection mechanism against unauthorized access to information. The entire computer network can be controlled from the center of the control node.

Network block diagram

Network Logic

The network should use some method to determine which node should use the communication lines and for how long. These functions are implemented by a network protocol that is required to prevent more than one user from accessing the bus at any given time.

If two sets of data are placed on the network at the same time, data conflicts and data loss occurs. Two de facto standard network protocols are currently in use: Ethernet and Token Ring.

This project will use the Gigabit Ethernet standard, supports transmission speeds up to 1000 Mbps. 1000BASE-T, IEEE 802.3ab is selected as a subspecies, a standard that uses a twisted pair of categories 5e or 6. All 4 pairs are involved in data transmission. Data transfer rate 250 Mbps over one pair.

Ethernet packet technology of computer networks, mainly local. Ethernet standards define wired connections and electrical signals at the physical layer, frame format and media access control protocols at the data link layer of the OSI model. Ethernet is mainly described by the IEEE 802.3 group standards.

Advantages of Ethernet:

known technology;
availability.
provides fast, efficient data delivery required for real-time data exchange.

Network address structure

Each computer must have its own, unique name. But the name of the workgroup, on the contrary, must be the same on all computers. The name of the group and computer can be anything, but the names most commonly used for a group are WORKGROUP or MSHOME . In addition to the name, the computer can also be provided with a description that will help you understand what kind of computer it is.

IP assignment -addresses and subnet masks:

Like the Internet, each computer on our local network must have its own IP - an address consisting of digits separated by dots. And this is not surprising, since in both cases the connection is carried out according to the protocol TCP/IP. IP - addresses of computers in the local network are most often assigned based on the following pattern: 192.168.0.X

The first part of the address remains unchanged in any case, and instead of X, you can substitute any number in the range from 0 to 255. Since there are 3 computers in this organization, we will replace X with the computer number.

IP example - computer addresses: 192.168.0.1.

IP -the address for the server will be 192.168.0.0, and for the printer 192.168.0.99.

Second setting option TCP/IP is called the subnet mask. It must be the same on all computers: 255.255.255.0

Network software

The operating system used is Windows 8. It includes all the features that the Windows 7 version can boast of and also has a number of serious additions:

The features of this OS include such as joining a domain, Group Policy (GP) control, searching for available printers, automatic network backup.

Windows Server 2012 R2 will be installed on the server computer.

Windows Server 2012 R2 brings Microsoft's experience in building and delivering global cloud services to infrastructure with new capabilities and enhancements for virtualization, management, storage, networking, virtual desktop infrastructure, access and information protection, web platform and platform applications, as well as many other components.

If your organization's network uses 802.1X password authentication methods for wired and wireless connections through Ethernet switches and wireless access points, users of non-domain-joined Windows 8.1 and Windows Server 2012 R2 computers and devices may experience Bring your devices to your organization and take advantage of password-based credential reuse.

With EAP and PEAP authentication methods configured, users can provide their credentials the first time they connect to the organization's network and then connect to all the resources they need without having to re-enter them because the credentials are stored locally for reuse .

This is especially useful for users who connect to multiple network resources such as intranet websites, enterprise printers, and line of business applications.

For security reasons, when you disconnect your computer or device from the network, your saved credentials are deleted.

This capability is available for non-domain-joined computers and devices running Windows 8.1 and Windows Server 2012 R2 if the following authentication methods are implemented on the network.

EAP combined with MSCHAP version 2 (PEAP-MS-CHAP v2)
PEAP-EAP-MS-CHAP v2
EAP-TTLS in combination with EAP-MS-CHAP v2

In Windows 8.1 and Windows Server 2012 R2, this feature is enabled by default.

Microsoft Windows Server 2012 R2 Essentials

Price: 22062 rub.

As a program for monitoring, we choose Total Network Inventory software for network inventory and accounting of computers for offices, small and large corporate networks. Total Network Inventory collects the following information about computers:

Processor type and frequency, multiplier, socket type, etc.
Motherboard model and manufacturer, chassis name and manufacturer, BIOS information, system and memory slots, ports, etc.
Memory size and number of modules.
Information about the monitor and video adapter.
Name, size, type of all hard drives, CDs, drives and Flash drives, information about logical drives.
Sound devices, installed video and audio codecs.
NIC models, IP and MAC addresses, DHCP, DNS and WINS settings.
Models, types, and settings of installed printers.
Names and types of modems.
List of all system devices.
Operating system name, type, version, build, serial number, etc.
OS updates and patches.
Programs installed on users' computers.
The contents of the Program Files folder on users' computers.
Programs that start automatically when the OS boots.
Names and versions of anti-virus software.
Database drivers.
Environment Variables.
All visible and hidden shared folders (Shared).
All running processes.
Services.
User accounts.

Total Network Inventory polls all computers on the network and provides you with complete information about the OS, its updates, hardware, installed software, running processes, etc. This information is entered into a centralized database. In this way, network administrators can quickly create flexible reports about every computer on the network. The program does not require client installation and does not need any pre-installed software.

Total Network Inventory

Price :18600

Network protection

Ensuring information security is one of the most important and at the same time the most complex and expensive tasks. A systematic approach is very important here, when individual problems are solved within the framework of the entire system, and there is no isolated plugging of holes.

Windows Defender This is an anti-virus program that was developed by Microsoft independently and is present in the latest versions of Windows operating systems. Windows Defender itself is a full-fledged antivirus based on Microsoft Security Essentials and can protect against most modern threats. Windows Defender could be seen in some versions of Windows 7, but there it only performed passive virus protection and worked as a virus scanner. With regards to the new version of Windows 8, here it is already able to work in real time and perform active computer protection. In Windows 8, Defender or in Russian Windows Defender starts immediately after the system starts, which gives users the opportunity to use it as the main computer protection and at the same time do without purchasing other anti-virus programs.

Firewall is software or hardware that prevents attackers and certain types of malware from gaining access to your computer over a network or over the Internet. To do this, the firewall checks data coming from the Internet or over a network and either blocks it or allows it to reach your computer.

A firewall is different from antivirus and antimalware applications. A firewall protects against worms and intruders, antivirus software protects against viruses, and antimalware protects against malware. All three types of protection must be used. You can use Windows Defender (this antivirus/antimalware software comes with Windows 8) or use another antivirus/malware application.

Only one firewall application should be running on a computer (in addition to the firewall that is usually built into a network router). Having multiple firewall applications on a computer can cause conflicts and problems.

Windows Firewall is included with Windows and is enabled by default.

The operation of the firewall is shown in.

Firewall operation

The firewall creates a barrier between the Internet and the computer

The firewall is enabled for all network connections.
The firewall blocks all incoming connections except those explicitly allowed by the user.
The firewall is enabled for all types of networks (private, public, and domain).

Windows Firewall and Windows Defender directly included in the assembly Windows 8 and do not require additional installation.

fault tolerance

Fault tolerance the property of a technical system to maintain its operability after failure one or more constituent components. Fault tolerance is determined by the number of any consecutive single component failures, after which the operability of the system as a whole is maintained.

The basic premise of the four basic principles The network must work even under attack. The first step is to define the end devices. What is a terminal device? In this model, the target device is any of the devices on which real work is performed: desktop computers, servers, and mobile devices.

Having defined the concept of terminal devices, they proceed to the development of a strategy for their protection. Such a strategy, in fact, consists of four basic principles of endpoint security and is characterized by the following goals:

protection of the terminal device from attacks;

provision of the terminal device with a self-healing function;

network bandwidth control;

providing network self-healing.

With these goals in mind, the four core principles of endpoint security can be summarized as:

strengthening the protection of terminal devices;

fault tolerance of terminal devices;

network prioritization;

network fault tolerance.

To improve network fault tolerance, firstly, it is desirable to automate the process as much as possible.

Secondly, you need to perform centralized monitoring of the network in order to know what is happening in real time. Although one of the goals of the two principles of fault tolerance is to reduce the indirect costs of such monitoring as much as possible, it is sometimes necessary to manually implement protection measures and take countermeasures. In addition, even under normal conditions, equipment failures occur.

Thirdly, it is necessary to organize feedback. As attacks become more and more sophisticated, it must be recognized that defenses can only remain reliable by constantly investing in strengthening them. At the same time, it is important to understand that network security costs are difficult to justify to top management as operating costs of paramount importance.

That is why constant monitoring and feedback is very important. The better we understand and can demonstrate the reality of threats and attacks occurring around the perimeter and within our network, the more justified the increased attention and spending on protecting these business resources looks.

Thus, the aforementioned Total Network Inventory monitoring program is used to improve network fault tolerance.

Conclusion

In the course of the work done, a local network was built of 3 computers and a printing device using Ethernet technology. There is access to the Internet, there is also a server on the network and access to it is carried out from any computer in the organization. Knowledge was studied and consolidated in the following areas: general principles of building networks, basic terminology, technologies of local networks, building local networks.

The cost of printing equipment RUB 42,860

The cost of network equipment is 56,360 rubles.

The cost of the software is 40,662 rubles.

As a result, the total cost of all network equipment, materials and software amounted to 139,882 rubles.

List of used literature

E. Tanenbaum "Computer networks" 2012

V.G. Olifer, N.A. Olifer “Computer networks. Principles, technologies, protocols.» 2006

http://www.inetcomp.ru/local_area_network_lan.htmlDefinition of a local area network.

http://life-prog.ru/view_zam2.php?id=3

Topologies of networks.

http://nix.ru/

Choice of accessories.

http://nettech.dn.ua/get-news/196/

Information about twisted pair.

http://life-prog.ru/view_apparprog.php?id=102

Internet protocols

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Introduction

Today there are more than 130 million computers in the world and more than 80% of them are connected in various information and computing networks from small local networks in offices to global networks such as the Internet, FidoNet, FREEnet, etc. The global trend towards connecting computers in a network is due to a number of important reasons, such as the acceleration of the transmission of information messages, the ability to quickly exchange information between users, receive and transmit messages (faxes, E-Mail letters, electronic conferences, etc.) without leaving the working places, the ability to instantly obtain any information from anywhere in the world, as well as the exchange of information between computers of different manufacturers operating under different software.

The application in practice of such huge potentialities that the computer network carries and the new potential rise that the information complex experiences at the same time significantly speeds up production processes.

On the basis of an existing computer park and a software package that meets modern scientific and technical requirements, there is a need to develop a fundamental solution to the issue of organizing an IVS (information and computer network), taking into account the growing needs and the possibility of further gradual development of the network in connection with the emergence of new technical and software solutions.

The main purpose of graduation qualifying work is the design of the local area network of the training center.

To achieve this goal, it is necessary to solve the following tasks.

Conduct an analysis of existing approaches to the design of the LAN.

Determine the structure and information flows of the training center.

Design a local area network of the training center.

Calculate the cost of LAN design costs.

Existing approaches to designing local area networks

The concept and classification of local area networks

Computer network - a set of software technical means, which ensure the exchange of information between two or more users working on different (stand-alone) computers connected to each other.

Computer networks are created in order to enable geographically dispersed users to exchange information with each other, use the same programs, common information and hardware resources.

Resources are understood as data, applications (programs), various peripheral devices (printers, modems, scanners, hard and floppy disks etc.).

According to some estimates, more than half of the operating computers are connected to networks.

Usage computer networks has many advantages:

Reduce costs by sharing a variety of databases and hardware

Standardization of applications - all users work on the same software (software), "speak the same language"

Efficiency of obtaining information on the job

Effective interaction and planning of working time (holding discussions, operational meetings on the job)

The common components of all networks are:

Servers (server) - computers that provide their resources to network users;

Clients (client), workstations - computers that access network resources provided by the server (servers);

Environment (media) - means of information transmission;

Shared data - files transferred by servers over a network;

Shared peripherals.

Networks emerged as a result of the creative collaboration of computer and communication technology specialists. Computing networks are divided into two types: local and global.

To create a single information space that can cover all users of the enterprise and provide them with information created at different times and in different software, use a local area network (LAN). A LAN is understood as a joint connection of several separate computer workstations (workstations) to a single data transmission channel. The simplest network (English Network) consists of at least two computers connected to each other by a cable. This allows them to share data. All networks (regardless of complexity) are based on this simple principle. The birth of computer networks was caused by practical needs - to be able to sharing data.

The concept of a local area network (English LAN-Lokal Area Network) refers to geographically limited (territorially or production) hardware and software implementations in which several computer systems connected to each other through appropriate means of communication. Through this connection, the user can interact with other workstations connected to this LAN.

Local area networks are classified according to several criteria:

There are two main types of networks: peer-to-peer and server-based networks. In a peer-to-peer network, all computers are equal. there is no hierarchy among computers and there is no dedicated server. Typically, each computer functions as both a client and a server; in other words, there is no single computer responsible for administering the entire network. All users decide for themselves what data on their computer to make publicly available over the network. To date, peer-to-peer networks are hopeless. If more than 10 users are connected to the network, then a peer-to-peer network, where computers act as both clients and servers, may not be productive enough. Therefore, most networks use dedicated servers. A dedicated server is a server that functions only as a server (excluding client or workstation functions). They are specially optimized for fast processing of requests from network clients and for managing the protection of files and directories. Server-based networks have become the industry standard. There are also combined types of networks that combine the best qualities of peer-to-peer networks and server-based networks.

In industrial practice, LANs play a very important role. Through a LAN, the system combines personal computers located at many remote workplaces that share equipment, software and information. Workplaces of employees are no longer isolated and are combined into a single system. All LANs operate in the same standard adopted for computer networks - the Open Systems Interconnection (OSI) standard.

Global networks. To work in global network modem required. In this case, the asynchronous transmission of each character (letter or number) is carried out using ten bits (8 bits are required to transmit a character and two service bits - start and stop).

Thus, at a data rate of 28800 bps, 2880 symbols per second are transmitted on the line. At this data rate, it takes just over one second to send one page of text containing 3,000 characters.

The speed of modern modems is different. Industrial models of modems have been developed that operate at speeds of 14400 bit/s, 16800 bit/s, 28800 bit/s, 33600 bit/s and 56000 bit/s.

Currently, there are more than 200 global networks registered in the world. Global networks (as well as local ones) consist of computers connected by communication channels. Global Area Networks (WANs) around the world are interconnected with the help of the Internet.

In order to operate on the DHW, the user must have the appropriate hardware and software. In the simplest case, a modem must be additionally installed from the hardware, with the help of which communication is carried out via a telephone line (for example, from an apartment).

The software is divided into two classes:

server programs located on the network node that serves the user's computer;

client programs that are located on the user's computer and use the services of the server.

Global networks provide users with a variety of services:

work with distributed databases,

Email,

teleconference,

real time communication,

file transfer, etc.

Each service (sometimes they say service, service) works according to certain rules (protocols).

For the implementation of each network service requires its own server program and its own client program. For example, there are mail servers and teleconferencing (news) clients, servers, and clients.

At the same time, modern navigator programs (researchers, browsers, browsers) are gradually taking over the functions of individual global network services and becoming “universal” clients.

The term "server" has a second meaning.

A server is also called a computer on which server programs are installed. Several server programs can run on one server-computer at once. Most often we will understand the term ("server" is a certain computer)

The term "network topology" refers to the path that data travels over a network. There are three main types of topologies: star, ring, and bus.

Star Topology

Figure 1.1 - Star Topology

The concept of a star network topology comes from the field of mainframe computers, in which main machine receives and processes all data from peripherals as an active data processing node (Fig. 1.1). This principle is applied in data transmission systems, for example, in e-mail Relcom networks. All information between two peripheral workstations passes through the central node of the computer network.

Network throughput is determined by the computing power of the node and is guaranteed for each workstation. Collisions (collisions) of data do not occur.

Cable connection is quite simple, poppy like every work station connected to the node. Cabling costs are high, especially when the central site is not geographically located in the center of the topology.

When expanding computer networks, previously made cable connections cannot be used: a separate cable must be laid from the center of the network to a new workplace.

The star topology is the fastest of all computer network topologies, since data transmission between workstations passes through the central node (if it performs well) on separate lines 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.

The performance of a computer network primarily depends on the capacity of the central file server. It can be a bottleneck in a computer network. If the central node fails, the operation of the entire network is disrupted.

The central control node - the file server implements the optimal protection mechanism against unauthorized access to information. The entire computer network can be controlled from its center.

Ring topology

With a ring network topology, workstations are connected to each other in a circle, i.e. workstation 1 with workstation 2, workstation3 with workstation 4, etc. The last workstation is linked to the first. The communication connection is closed in a ring (Fig. 1.2).

Laying cables from one workstation to another can be quite difficult and expensive, especially if the geographic location of the workstations is far from the ring shape.

Messages circulate regularly around the circle. The workstation sends information to a certain end address, having previously received a request from the ring. Message forwarding is very efficient, as most messages can be sent in a ringback request to all stations. The duration of information transfer increases in proportion to the number of workstations included in the computer network.

The main problem with a ring topology is that each workstation must actively participate in the transfer of information, and if at least one of them fails, the entire network is paralyzed. Faults in cable connections are easily localized.

Connecting a new workstation requires a short-term shutdown of the network, as the ring must be open during installation. There is no limit to the extent of a computer network, as it is ultimately determined solely by the distance between two workstations.

Bus topology

With a bus topology, the information transmission medium is presented in the form of a communication path available to all workstations, to which they must all be connected. All workstations can communicate directly with any workstation on the network.

Workstations at any time, without interrupting the operation of the entire computer network, can be connected to it or disconnected. The functioning of a computer network does not depend on the state of a separate workstation.

In the standard situation for an Ethernet bus network, a thin cable or Cheapernet is often used - a cable with a tee connector. Disconnecting and especially connecting to such a network requires a bus break, which causes a disruption in the circulating flow of information and a system hang.

New technologies offer passive plug boxes through which workstations can be disconnected and/or connected while the computer network is running.

Due to the fact that workstations can be connected without interrupting the network processes and communication environment, it is very easy to listen to information, i.e. branch information from the communication medium.

In a LAN with a direct (not modulated) transmission of information, there can always be only one station that transmits information. To prevent collisions, in most cases, a temporary separation method is used, according to which for each connected workstation, at certain points in time, the exclusive right to use the data transmission channel is granted. Therefore, the requirements for the bandwidth of a computer network at increased load increase, for example, when new workstations are introduced. Workstations are connected to the bus by means of TAP (Terminal Access Point) devices. TAP is special type connection to the coaxial cable. The needle-shaped probe is introduced through the outer shell of the outer conductor and the dielectric layer to the inner conductor and is attached to it.

In a broadband modulated LAN, different workstations receive, as needed, the frequency at which these workstations can send and receive information. The transmitted data is modulated on the respective carrier frequencies, i.e. Between the information transmission medium and the workstations are, respectively, models for modulation and demodulation. The technology of broadband communications allows you to simultaneously transport a fairly large amount of information in a communication medium. For the further development of discrete data transportation, it does not matter what initial information is fed into the modem (analogue or digital), since it will be converted in the future anyway.

Table 1.1 - Main characteristics of the three most typical typologies of computer networks

Characteristics	Topologies of computer networks

Expansion cost	Minor
Joining subscribers	passive	Active	passive
Failure protection	Minor	Minor
System dimensions			Limited
eavesdropping protection			Minor
Connection cost	Minor	Minor
System behavior under high loads		Satisfactory
Ability to work in real time	Very good
Cable routing		Satisfactory
Service	Very good

Currently, experts and business representatives are the most effective way creating a unified information environment in the company recognized the construction of local networks. A local area network (LAN) is a group of computers connected to each other that can share common resources. Data is transmitted in the form of packets, while different technologies are used to control this process. At the moment, the most demanded technology is Ethernet - a technology for transmitting data via cable. The physical medium for a data transmission channel in a wired network is cables, usually twisted pair or fiber optic cable. A single information space in a company is necessary so that its employees - network users - can quickly exchange data, use a variety of resources and devices together, and perform many other actions necessary for the successful implementation of the company's core business.

Key benefits of local area networks for business:

Ensuring continuous access of the company's personnel to shared resources - documents, databases, etc., saving time and ensuring a high level of communication among employees;

The possibility of sharing office equipment - printers, faxes, scanners, copiers, allowing you to save on the purchase of additional devices;

Simplicity and ease of moving and adding jobs and equipment, reducing the cost of funds and time of the company's staff;

Increase the security of critical business information through the use of data protection systems.

ALP Group specialists carry out work on the organization and construction of switched local networks, using modern technologies and their own serious experience gained over many years of creating, maintaining and technical support of engineering systems for domestic business. Creating a local network is a responsible process that requires a high degree of professional training and skill level. After all, the stable operation of the entire company depends on the stability of the LAN.

Basic requirements for a local area network

Ease of control

Adaptation to the most popular types of cables and devices

Availability of spare channels and potential for further expansion and optimization

Stages of building computer networks

1. Development. It includes a survey of the territory where the local network is supposed to be built, a discussion with the client of the tasks that it will perform, the formation of a technical assignment and the choice of equipment.

2. Installation and. At this stage, the cable is laid, after which the installation and subsequent configuration of equipment, software and data protection systems are carried out.

3. Testing. The LAN is checked for its performance, stability, security and compliance with accepted norms and quality standards.

4. Warranty and post-warranty service. Providing support and carrying out preventive and repair work of the network and equipment.

The exchange of information in the LAN occurs according to certain rules, which are called protocols. Different protocols describe different aspects of the same type of communication. At the same time, taken together, they form the protocol stack. Workstations that are connected to the local network can be combined with each other in several ways. The configuration of a network or the way its elements are connected is commonly called a topology. Experts identify three main schemes for combining computers when building a local area network - a "star", "common bus" and "ring".

"Star". Is the most common. When using the topology, each node (individual workstation) is connected to the LAN using its own cable, one end of which is connected to the network adapter, and the other to the hub.

The operation of a network created according to this principle provides the enterprise with several important advantages:

A rather low cost of adding new jobs (up to about 1 thousand units);

Independent functioning of computers: if one of them fails, the rest will continue to work.

It should be borne in mind that the star topology has its drawbacks. If the hub turns out to be faulty, then the stations connected to it will also not be able to work. Also, when creating a local network of the "star" type, a cable route of considerable length may be required.

"Common bus". A topology in which information passes through workstations connected in parallel to a backbone (main cable). However, only the addressee that has the IP address from which the information was requested receives data upon request. The inconvenience of this principle of organizing a local area network can be considered that if the connection of one PC to the backbone is broken, all the others will fail. It is worth considering the fact that the configuration of the "common bus" type will not always be able to meet the increased requirements of the enterprise for the level of LAN performance.

"Ring". It is a way to serially connect PCs with each other and transmit a one-way signal in a circle. In fact, each PC repeats and amplifies the signal, transmitting it further over the network. This scheme also has its drawback: if one workstation fails, the entire network will be stopped. It is also worth noting the limitations of the total length. However, a significant advantage of this topology can be considered optimal load balancing for equipment and convenience when laying cables.

The topology most suitable for organizing a LAN is always selected individually. The main selection criteria are the specific needs of a particular company. A very commonly used circuit is a combination of different topologies. For example, the snowflake configuration is used in high-rise buildings. At this principle creating a local network requires the use of file servers for different workgroups of the company and a common central server.

LAN Features

At enterprises, local networks are characterized by the organization of working groups - the association of several personal computers into one group with the same name. Network administrators are responsible for the smooth functioning of the LAN as a whole or some of its sections. In complex networks, the rights of administrators are strictly regulated, and the actions of each member of the network administrators group are also recorded.

The creation of a local network is most often carried out on the basis of Ethernet technology. To organize simple networks, routers, modems, switches and network adapters are used. In conventional local networks, it is customary to use static or dynamic routing.

Building a LAN usually involves the use of technology of the two initial layers of the OSI network model - channel or physical. Their functionality is enough to carry out work within the framework of one of the most common topologies - "ring", "star" or "common bus". PCs used in building a corporate network can support higher level protocols. Other protocols can be installed and used in network nodes, but the functions carried out with their help will no longer relate directly to the LAN.

ALP Group specialists will perform the whole range of works on creating a local network for your company using modern technologies and compliance with all international standards - with high quality and in optimal time.

Let's decide on the starting points: a small company, let's say about 15-50 employees. As a rule, there is no qualified network specialist. And most likely it was the "dedicated" for working with the network, the network administrator by state. Let's agree - your specialist is still needed. And he needs to be paid money, and good money at that (what a horror, right? That's news for many directors). I will try in this article (perhaps with a continuation) to act as a network administrator for such a small company. So, we build a network ourselves. Why not? There are many arguments "against" "home-made", and all of them are true (unless, of course, this is not outright "noodles" from a potential contractor). But still, you can do it yourself. Arguments "for" also abound. We will not bring them here - we believe that we decided to do it ourselves. We will not make new-fangled radio, Wi-Fi and other networks, but an inexpensive, but high-quality cable network of a traditional wired type for the daily work of the company. However, one must understand that the work must be performed by a specialist (or several).

Introduction

Let's decide on the starting points: a small company, let's say about 15-50 employees. As a rule, there is no qualified network specialist. And most likely it was the "dedicated" for working with the network, the network administrator by state. If there is - a jack of all trades, and often forced to deal with some "urgent" business like Windows installation or drivers on some computer, instead of working with the network. Together with other "computers" (if any). Is the network working? Let the deck through the stump, well, okay, a little later we will do it (let's do it).

Let's agree - your specialist is still needed. And he needs to be paid money, and good money at that (what a horror, right? That's news for many directors). I will try in this article (perhaps with a continuation) to act as a network administrator for such a small company.

Initial data

So, we build a network ourselves. Why not? There are many arguments "against" "home-made", and all of them are true (unless, of course, this is not outright "noodles" from a potential contractor). But still, you can do it yourself. Arguments "for" also abound. We will not bring them here - we believe that we decided to do it ourselves.

However, one must understand that the work must be performed by a specialist (or several). You can’t train (“though inferior, but your own”) and raise your specialist in this way. You can put your own into practice to the person doing the work (we will not take into account drilling holes with a puncher in the walls and fixing the cable channel - any man should be able to do this).

One more factor, let's add, so to speak, "pepper" - our company, in addition to the office, has a store and a warehouse, which are quite remote.

We will not make new-fangled radio, Wi-Fi and other networks, but an inexpensive, but high-quality cable network of a traditional wired type for the daily work of the company. For work, not for surfing news and/or porn sites from a laptop from a hotel couch. We may return to these issues in the sequel (not to the hotel and others like it, of course, but to modern technologies).

Last, and also very important: we count money, but we are not greedy.

Plan

At the very beginning, you must definitely do one very simple, but very important thing - take a few pieces of paper, a pencil and sit down for a draft business plan. It is very important to more or less clearly "pencil" all the keywords that come to mind from the question "what do I want from the network." Sketch these positions on the first sheet. On the second - to group them into separate categories. For example - the category "services". What kind of services do we want to receive from the network, and what quality? What do we need? File-, ftp-, print-, internet service?

It would seem that everything is clear, why write, draw? But, if you do not take everything on a pencil - then it will be worse. For example, it turns out that you need to go to the director and / or to the accounting department: “Sorry, we bought the wrong piece of iron here, and not for 100 USD. necessary, but for 500.

Now you can take a break to add what you need, throw away the excesses. And put it all aside for at least a day. Then the draft can be transferred to the third sheet. With "final" additions and corrections. Why quotes - you yourself understand, this is not the last sheet, and far from the last "sketches".

Services are services, however, the base is SCS, that is, a structured cabling system. Let's try not to run too far ahead of the horse.

Usually there are two options - an office "from scratch" and an office "ready". The first case - bare walls and ceiling, repair - ours, and that's good. The second option is "done". Those. - we begin the external laying of the SCS. But, let's not start with that, yet.

Electricity

An important stage, because God forbid, not just one or two ordinary computers “fly”, everything can “fly”. Well, we believe that everything is in order with the power network in our office. There is only one important point here - uninterruptible power supplies (UPS). They are necessary. Believe me. A diesel generator is, of course, good, but not necessary in all cases, but sparing money on installing a UPS on each server or communication closet is simply stupid. However, we will return to the issue of UPS in due time.

SCS and basic active equipment

Structured Cabling System (SCS) is one of the cornerstones. SCS must be properly designed and built. Let's break the question into sections:

* Communication cabinet (with "stuffing")
* Cable lines
* Subscriber sockets

This is where the plan of the premises, with clearly marked places for employees, is very useful. It must be borne in mind - it’s also good to note power sockets. Next - in order, let's start with the closet.

Communication cabinet: find a convenient place to install a cabinet with equipment. Important to find optimal distance to workstations, in order to reduce the cost of twisted pair, cable channel and other “little things”. There are many factors: limiting the length of the line to 100 meters (or rather, 90 meters, according to the classical formula 90 + 5 + 5); office layout (where is it convenient to put or hang a cabinet, is it convenient to pass the walls when pulling the cable, will the cooling not put pressure on the ears of customers or employees, etc.); in fact, the design of the cabinet (floor, wall, its height in U, the amount of equipment that needs to be installed in it, whether there will be a cooling unit).

There are a wide variety of cabinets, you need to carefully look at the prices and quality of the proposed purchase, do not forget to stock up on capacity (!) In those very U. Be sure to have at least one shelf. However, in some places it is quite possible to do wall brackets, to secure the equipment. But this is specificity. We will assume that for the office we chose a 12-14-height cabinet with a glass door. Looking ahead a little, it is necessary to mention what will be installed inside:

Shelf: it will always come in handy, even if it is empty (I doubt it) - it can be removed. You should not spare 10-20 dollars when you have to "suddenly" put a device or two in the closet, remember these lines.

Switch (switch): 24 ports at the lower limit of the company's employees in the office - let there be 10-20 people in the office (and do not forget about servers and other network equipment). However, if there is a high density of jobs, there will be no problems adding the required number of switches and other related equipment.

Distribution panel (patch panel): 24 ports, everything is the same with the switch. It is on the patch panel that all lines from workstations and servers will be reduced.

Panel (block) of power sockets: by the number of connected equipment in the cabinet, plus a supply of 1-2 sockets on the panel. Here we may well expect an "ambush" if we have to connect power supplies - it may not be enough (remember 99.9% of the market filled with surge protectors with tightly-obliquely planted sockets).

You can put a cheap, simple option (that's when a shelf comes in handy, but you can also put it on the floor of a cabinet), you can also use a 19 ”UPS designed for installation in a cabinet.

So, having looked at the products offered on the market, we believe that we have decided on a cabinet: 14-height (14 U). For example, Molex MODBOX II 14U:

Suitable for 19" 1U fan cabinet
. Standard cabinet set:
. Lightweight steel profile provides the cabinet with greater rigidity and strength
. Aesthetic glass door with lock
. Door of universal design with the possibility of hanging (left, right)
. 19" depth adjustable frame
. Grounding of all cabinet elements
. The cable entry holes are equipped with a protective brush to prevent dust from entering the cabinet

Switch. His choice is a more complex issue. Absolutely cheap switches do not want to be considered. There are devices that are more expensive (and very expensive), but you still have to choose from two types: unmanaged and managed.

Let's take a look at the following two devices: ZyXEL Dimension ES-1024 and ES-2024:

It is a cost-effective Fast Ethernet solution and can be used to build highly efficient switched networks. The data staging feature significantly reduces latency on high-speed networks. The switch is designed for workgroups, departments or backbone computing environments for small and medium enterprises. Due to the large address table and high performance, the switch is an excellent solution for connecting departmental networks to a corporate backbone or for connecting network segments.

Specifications:

24-port Fast Ethernet Switch
. IEEE 802.3, 802.3u and 802.3x compliant
. RJ-45 Ethernet ports with 10/100 Mbps auto-speed selection
. Automatic crossover cable connection detection on all 10/100 Mbps RJ-45 Ethernet ports
. Back-Pressure-Base flow control support on half-duplex ports
. Pause-Frame-Base flow control support on full duplex ports
. Store-and-forward switching support
. Support for automatic address detection
. Max Speed wired network transfers
. Built-in MAC address table (8K MAC address capacity)
. LED indicators power supply, LK/ACT and FD/COL

Application of ES-2024 Switch will allow you to unite a group of users and connect them with high-speed lines to the corporate network. Additionally, it will be possible, thanks to the use of iStackingTM technology, to combine a group of switches for network management, regardless of their location.

Specifications:

24 RJ-45 ports with 10/100 Ethernet auto-speed selection and automatic detection crossover cable connections
. 2 x 10/100/1000 Ethernet ports
. 2 mini-GBIC standard slots, combined with ports
. 8.8 Gbps non-blocking switching bus
. Support for IEEE 802.3u, 802.3ab, 802.3z, 802.3x, 802.1D, 802.1w, 802.1p protocols
. MAC address table 10Kb
. VLAN support: Port-based and 802.1Q
. Possibility to limit the rate on the port
. 64 static VLANs and up to 2Kb dynamic VLANs
. MAC address filtering
. Support for ZyXEL iStacking™, up to 8 switches (up to 24 in the future) managed by a single IP address
. Control via RS-232 and WEB-interface
. Telnet CLI
. SNMP V2c(RFC 1213, 1493, 1643, 1757, 2647)
. Control over IP: static IP or DHCP client
. Firmware update via FTP
. Updating and Saving System Configuration
. Standard 19" Rack Mount

As you can see, there is a difference, and a very significant one. As there is a difference in price - approximately 100 and 450 dollars. But, if the first switch is a decent, but "stupid" box, then the second one is in some sense intelligent, with much more functionality and manageability, with potential strengths. We choose the second option. We want to build a good network, don't we?

By the way, right now it is quite time to ask yourself why, in fact, we are building a “hundredth” network? Today, every second computer has not just a gigabit network interface, but two gigabit ones?

This is the case where you can safely save. The fact is that a 100-megabit network is more than enough for an office to work. If, moreover, the switch is decent! Yes, but on the two gigabit interfaces of the selected switch - safely "sit down", for example, two servers. Here they are, the servers, it's just for the benefit.

Of course, you can take something like ZyXEL GS-2024 and put everyone on a gigabit channel, but this is just a case of unreasonable spending of money, and for that kind of money we can buy a complete cabinet with a more complete filling.

Patch panel. Also the case when you should not save much. Choose a panel like Molex 19" 24xRJ45, KATT, 568B, UTP, PowerCat 5e, 1U.

Compliance with the requirements of category 5e. The compensation system is implemented directly on printed circuit board. The use of CATT type connectors speeds up and simplifies cable installation. Dedicated space for labeling channels. The panel is powder coated. All necessary fastening and marking elements are supplied in the kit.

There are many options here, as already mentioned, you can put any cheap one, it can be more expensive, you can use a 19” rack-version - there will be beauty at all. Who doesn't know APC? You can see for example this UPS:

APC Smart-UPS SC 1500VA 230V - 2U Rackmount/Tower

Or, like this:

Without delving into the characteristics, we note that many devices are equipped on request with guides for installing the UPS in a 19 "rack. Also, it is possible to equip, if desired, with an SNMP module for monitoring and managing the UPS over a computer network. Of course, this will cost money, but It can be very convenient.Let's opt for IPPON.It should be noted that models 1500, 2000 and 3000 can be equipped with SNMP support, but not 750 and 1000.

Power outlet block:

Without any special comments - maybe you can find something cheaper, easier. But a dozen "strangled raccoons" will not make the weather.

It remains to remember to decide whether a fan unit is needed in the cabinet? Expensive pleasure, especially when paired with a thermostat unit. However, we will attribute this to the specifics of the place / office.

We more or less figured out the closet, there were all sorts of “little things”, without taking into account which there will be annoying delays later:

* Screws with nuts for mounting equipment in the cabinet;
* Nylon non-opening ties for laying and fastening the cable (packs of 100 pieces, 100, 150, 200 mm long);
* Marking for the cable (adhesive sheets with a protective layer).

In fact, we got to the SCS itself. A very important "detail" is the cable, which will be used for wiring the SCS. Yes, again a call not to save. A good twisted pair cable is a good investment. We take Molex, unshielded UTP PowerCat 5e cable.

The cable is the core element of the PowerCat product line. The line is designed for use in high-speed telecommunication networks (eg GigaEthernet 1000Base-T).

We, of course, will come to subscriber sockets, and then what? Next - buy the required number of patch cords to connect workstations. Naturally, you need to think over the length, look at the office plan mentioned above. But that is not all. You also need a strainded cable (normal - solid). This is a special twisted pair, "soft", from which patch cords are made. After all, sooner or later you will definitely need a patch cord of a greater length than there are ready-made ones at hand (if at all by that time they remain). it will be necessary - as you wish) to make short - 30-50 cm, patch cords for crossing SCS lines and active equipment in the cabinet itself. Therefore, we "take a pencil" a couple more packages of RJ45 connectors, in common parlance - "chips". And packaging of rubber caps for them.It is better to take soft caps and with a slot for the "chips" retainer, and not with a "pimple" for the retainer.

We have almost reached the network interfaces on user computers, but subscriber sockets are still needed. Someone against such a wonderful thing as Molex OFFICE BLOCK 2xRJ45? ;-)

Compliance with the requirements of category 5e. The modules are designed for high-speed telecommunication networks. Possibility of cable entry from the sides, top or rear. As standard, the modules are equipped with dust shutters. Ease of labeling channels. The built-in magnet simplifies mounting the modules to metal surfaces. Possibility of fastening with screws. Cable fastening inside the module without cable ties. Free choice of connection sequence (568A/B). Connector type "KATT" facilitating installation. The kit includes mounting elements. .

Here it is necessary to determine the quantity. After all, there are single options. Again we take the plan of the office. There is another important point in determining the installation locations for sockets - it is advisable to add one or two additional SCS lines to each office. One is just "just in case". What if the layout in the office changes a little or someone will need to connect a laptop? The second one is not bad to have based on the print server, for organizing network printing. It is very nice to have one or two network printers for your office or office that work without problems and whims of the owner (or Windows).

Do you think that's all? No. Another factor that is present in any office is forgotten - telephony. It's a good idea to think about this too: if telephones should be wired to some workplaces, then why not make a wiring in the general SCS? After all, the issue can be solved simply: throw a line or two to the necessary places, put an RJ-12 socket next to the RJ-45, even in one housing (unit). In the socket - DECT, for example, with several handsets, and in the cabinet we draw a line (lines) from the PBX - they can be put on sockets, neatly glued with Velcro inside and on the side. Lines from jobs - on them.

It seems like it's time to take on the cable channel and dowel-nails? Yes. It is time. But this is already clear to any handy man, we will not dwell on this for a long time. You just need to take into account the number of lines laid in the cable channel. And, of course, a small margin is needed. It is very good if the office has a suspended ceiling, the lines can be pulled behind it right to the workplace and lowered in a cable channel along the wall. When drawing lines, it’s a good idea to mark them (as well as sockets in the future). The easiest method is the first socket to the left of the door - No. 1, further in a circle.

After stretching the lines, you can start splitting the patch panel and sockets. Needless to say, this job requires accuracy and skill. It is at this moment that line marking will come in handy for us - if all the lines are split in order, then in the further operation of the SCS it will be possible to practically do without an installation map (layout), something like this:

Socket

However, this card is still needed in the future. Will definitely come in handy.

When laying cables, there are several simple rules(precisely simple ones, we will not delve into standards and other ISOs now):

* Do not severely bend, rub or step on the cable. Cable bending is allowed: during installation - 8, and, during operation - 4 radii of the cable itself;
* Do not lay lines near power lines: if necessary, lay them in parallel - at a distance of at least 20 cm;
* Crossing power lines is allowed, at a right angle;
* Mandatory testing by a cable tester.

Separately, about the last point. Remember the joke about the Japanese supply of something there? “Dear customers! We don't know why you need this, but we still decided to put in the boxes one defective chip for every ten thousand, according to your requirements. Yes, you can just split and forget. An experienced installer is not mistaken. However, a really experienced installer will definitely check, and not only the layout of the line, but also the quality.

Here we come to the most interesting moment. If we check a trifle with a simple and cheap tester, then to carry out tests and certify lines - no, it will not work:

Which exit? I really don't want to leave the issue of line quality unresolved. There are three options. The first is to buy a good tester, for example:

But, alas, we are very sorry for $6,000, even if it is for such a wonderful and necessary device.

It is a compact, handheld tool used for qualification, testing, and troubleshooting of coaxial and twisted-pair cabling in local area networks. The tester is recommended by leading manufacturers of information cabling systems for testing for system certification up to Class E inclusive. High level reliability, convenience and accuracy of the device provided him with one of the first places among the products of this class. For fast and high-quality testing of cable connections in an extended frequency range up to 350 MHz, digital pulse signal processing technologies are used.

The second option is to invite a familiar admin or installer who has such or a similar device. Of course, having previously bought a case of good beer. Half an hour of work, plus a beer evening in the pleasant company of a friend.

The third option is to officially invite specialists from a company that provides such services. and pay for these services. This is not so much, especially if you do not require a certificate on paper.

Remote workstations

Having "finished" (quotation marks because we must first still plan everything and make the necessary purchases and negotiations) with the work at the main office, we remember the warehouse and the store.

Now (in these notes) we will consider not a "tricky" solution like VPN, but the simplest one - organizing the connection of computer networks with subnets (workstations with a network) over a dedicated line. Effective, cheap and cheerful. By the way, allotments, of course, should be placed in a closet and connected to sockets, like telephones.

If the distance and, accordingly, the resistance of the leased line are small, you can try to install a pair of "bridges", for example, the already mentioned firms ZyXEL Prestige 841С and ZyXEL Prestige 841. Model "C" is "master", so this device is best installed at the head office. These are inexpensive VDSL devices, but they give the necessary results for our task. What ZyXEL says:

Depending on the type and condition of the cable, as well as on the distance, the Prestige 841 paired with the Prestige 841C provides the following data exchange rate:

In the direction to the subscriber - within the range from 4.17 to 18.75 Mbps
. in the direction from the subscriber - from 1.56 to 16.67 Mbps
. total throughput lines can reach 35 Mbps

Specifications:

VDSL Ethernet Bridge
. LAN connection at 15 Mbps up to 1.5 km
. Plug&Play, transparent to all protocols
. Working in pairs
. Desktop execution
. Non-volatile memory (Flash ROM)
. Size: 181 x 128 x 30 mm

This option will give 18 Mb in each direction, ideally, of course. This is VDS.

When using Prestige 841 there is another plus. These devices have a built-in splitter, and we can get "free" telephony from a remote location. It is enough to plug into the “phone” socket on the one hand the telephone of the remote workplace, and on the other hand, connect the office mini-PBX.

If the VDSL bridges don't "stretch" the line, you need to look at other devices, xDSL. For example - something from the 79 series ZyXEL, SHDSL.

Optimization of the hardware and the use of advanced technologies have made it possible not only to reduce the dimensions of the device, but also to reduce the cost and improve functional characteristics. provide symmetrical connection at speeds up to 2.3 Mbps and can work on a leased 2-wire line both in point-to-point mode and as a client of an Internet provider hub.

Specifications:

. SHDSL router
. G.991.2 support up to 2.3 Mbps symmetrical
. Connecting networks or accessing the Internet over long distances
. Encapsulation PPPoA, PPPoE, RFC-1483
. TCP/IP Routing, Full NAT, Packet Filtering
. Support for IP Policy Routing, UPnP, connection redundancy
. Management via console, Telnet, Web, SNMP

The ideal speed is 2.3Mb over two wires. If you "charge" 4 wires, the speed will be correspondingly greater. However, these devices will cost a large amount - 400-500 dollars per pair. In any case, roughly speaking, the worse the quality of the line, the lower the speed and the higher the costs. However, we will postpone the tuning (tuning) of devices for the future, this is a separate conversation, especially since in the case of VDSL 841 this does not make too much sense at all. xDSL devices should be placed on a shelf in a closet. I told you it wouldn't be empty.

Internet connection

ZyXEL Prestige-660

A modern office is unthinkable without the Internet. To connect, we can use ADSL technology, for example - ZyXEL Prestige 660.

As ZyXEL describes this device:

Modem P-660R belongs to the fourth generation of ADSL modems and combines in one device the functionality necessary to connect an existing office or home network to the Internet: ADSL2+ modem, router and firewall. The modem will provide your office with a permanent Internet connection that works quickly and securely. Installation and maintenance of the P-660R modem is simple and will not cause any problems even for inexperienced users.

Main advantages of ZyXEL Prestige 660:

* High-speed Internet - up to 24 Mbps
* Reliable connection on problematic lines
* Free phone
* Permanent connection
* Does not require driver installation
* Works with W

Federal Agency for Education

State educational institution

Ufa State Aviation Technical University

In addition to the main components, the network can include uninterruptible power supplies, redundant devices, modern dynamically distributed objects and Various types servers (such as file servers, print servers, or archive servers).

When creating a LAN, the developer faces a problem: with known data on the purpose, the list of LAN functions and the basic requirements for a set of technical and software tools LAN to build a network, that is, solve the following tasks:

Determine the LAN architecture: select the types of LAN components;

Evaluate the performance indicators of the LAN;

Determine the cost of the LAN.

This must take into account the rules for connecting LAN components, based on network standardization, and their limitations, specified by the manufacturers of the LAN components.

The configuration of a LAN for an automated control system essentially depends on the characteristics of a particular application area. These features are reduced to the types of transmitted information (data, speech, graphics), spatial arrangement subscriber systems, intensity of information flows, admissible delays of information during transmission between sources and recipients, volumes of data processing in sources and consumers, characteristics of subscriber stations, external climatic, electromagnetic factors, ergonomic requirements, requirements for reliability, cost of LAN, etc.

Initial data for designing a LAN can be obtained in the course of a pre-design analysis of the application area for which an ACS should be created. These data are then refined as a result of decision-making at the design stages of the LAN and the construction of more and more accurate models of the automated control system, which makes it possible to formulate requirements for it in the "Terms of Reference for the LAN". The best LAN is the one that satisfies all the requirements of users, formulated in the terms of reference for the development of a LAN, with a minimum amount of capital and operating costs.

GOAL OF THE WORK

Gaining skills in choosing a topology, elements of a local area network, as well as calculating the signal delay time.

BRIEF THEORETICAL INFORMATION

LAN configuration design refers to the hardware design phase automated systems and is carried out at this stage after the distribution of the automated system function among subscriber stations of the LAN, the choice of types of subscriber stations, and the determination of the physical location of subscriber stations.

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

1. LAN topology.

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

Star-shaped (Fig. 1);

Ring (Fig. 2);

Tire (Fig. 3);

Tree-like (Fig. 1*);

Cellular (Fig. 4).

The topologies of computer networks can be very different, but only three are typical for local area networks: ring, bus, star. Sometimes, for simplicity, the terms are used - ring, tire and star.

Tree topology (hierarchical, vertical). In this topology, the nodes perform other more intelligent functions than in the star topology. Network hierarchical topology is currently one of the most common. The network management software is relatively simple, and this topology provides a point of concentration for management and error diagnosis. In most cases, the network is controlled by station A at the highest level of the hierarchy, and the distribution of traffic between stations is also initiated by station A. Many firms implement a distributed approach to the hierarchical network, in which, in a system of slave stations, each station provides direct control of stations lower in the hierarchy. From station A, stations B and C are controlled. This reduces the load on the LAN through the allocation of segments.

Mesh topology (mixed or meshed). A network with a mesh topology is, as a rule, a non-fully connected network of message switching nodes (channels, packets) to which end systems are connected. All CSs are dedicated point-to-point. This kind of topology is most often used in large-scale and regional computer networks, but sometimes they are also used in LANs. The attractiveness of the mesh topology lies in its relative resistance to overloads and failures. Due to the multiple paths from station to station, traffic can be directed around failed or busy nodes.

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

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

Fig.1. Star topology Fig.2 Ring topology

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Rice. 1* Distributed star topology

Fig.3 Topology

linear bus

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

In the case when the connected networks differ in all levels of control, an end system of the type Gateway, in which coordination is carried out at the level of application processes. By using gateway interconnect systems using different operating environments and high-level protocols

9. Initial data for the task

Users: students, teachers, engineers, programmers, laboratory assistants, technicians of the Department of Automated Control Systems of the USATU.

Functions:

1) the implementation of the educational process in laboratory, practical classes, the implementation of course and diploma design;

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

3) development of software for networking;

4) prevention and repair of equipment.

Calculation of the cost of LAN equipment:

The LAN must allow the connection of a wide range of standard and special devices, including: computers, terminals, external memory devices, printers, plotters, facsimile devices, monitoring and control equipment, equipment for connecting to other LANs and networks (including telephone networks) etc.

The LAN must deliver data to the destination with a high degree reliability (network availability factor must be at least 0.96), must comply with existing standards, provide a "transparent" mode of data transfer, allow simple connection of new devices and disconnection of old ones without disrupting the network for no more than 1 s; the reliability of data transmission should be no more than + 1E-8.

11. List of tasks for designing a LAN

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

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

11.3. Select the optimal LAN configuration.

11.4. Carry out an approximate routing of the cable network and calculate the length of the cable connection for the selected topology, taking into account transitions between floors. Since there are restrictions on the maximum length of one LAN segment for a given type of cable and a given number of workstations, it is necessary to establish the need to use repeaters.

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

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

The calculation in this case is based on table 2.

To calculate the total double (round trip) transit time for a network segment, multiply the segment length by the delay per meter taken from the second column of the table. If the segment has a maximum length, then you can immediately take the value of the maximum delay for this segment from the third column of the table.

Then, the delays of the segments included in the path of maximum length must be summed up and added to this sum is the delay for the transceiver nodes of two subscribers (these are the top three lines of the table) and the delays for all repeaters (hubs) included in this path (these are the bottom three lines tables).

The total delay must be less than 512 bit intervals. It should be remembered that the standard IEEE 802.3u recommends leaving a margin of 1 to 4 bit intervals to account for cables inside junction cabinets and measurement errors. It is better to compare the total delay with 508 bits rather than 512 bits.

Table 2.

Double network component delays fast ethernet(delays are given in bit intervals)

Segment type	Delay per meter	Max. delay
Two subscribers TX/FX		Two subscribers TX/FX
Two subscribers T4		Two subscribers T4
One subscriber T4 and one TX/FX		One subscriber T4 and one TX/FX



Shielded twisted pair
Fiber optic cable
		Repeater (hub) class I
TX/FX		Repeater (hub) class II with ports TX/FX
Repeater (hub) class II with ports T4		Repeater (hub) class II with ports T4

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

Calculation example for the network shown in fig. 5:

There are two maximum paths here: between computers (segments A, B and C) and between the upper (in the figure) computer and the switch (segments A, B and D). Both of these paths include two 100m segments and one 5m segment. Let's assume that all segments are 100BASE-TX and performed on category 5 cable. For two 100-meter segments (maximum length), a delay value of 111.2 bit intervals should be taken from the table.

Rice 5. Example of maximum network configuration fast ethernet

For a 5 meter segment, when calculating the delay, multiply 1.112 (delay per meter) by the length of the cable (5 meters): 1.112 * 5 = 5.56 bit intervals.

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

From the table of delay values for two class II repeaters - 92 bit intervals each.

All the listed delays are summed up:

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

it is less than 512, therefore, this network will work, although at the limit, which is not recommended.

11.6. Determine LAN Reliability

For a model with two states (working and not working), the probability of a component's operability, or, more simply, reliability, can be understood in different ways. The most common expressions are:

1. component availability

2. component reliability

Availability is used in the context of maintainable systems. It follows from the above that the component can be in one of three states: working, not working, in the process of restoration. The availability of a component is defined as the probability of its operation at a random moment in time. Availability is assessed by taking into account the average recovery time to working condition and the average time out of working condition. Reliability can be written:

______________mean time to failure ______________

mean time to failure + mean recovery time

Quantitative values of AIS reliability indicators should be no worse than the following:

The mean time between failures of the AIS software and hardware complex (KHTS) should be at least 500 hours;

The mean time between failures of a single AIS communication channel should be at least 300 hours;

The mean time between failures of AIS servers should be at least 10,000 hours;

The mean time between failures of a PC (as part of an automated workplace) must be at least 5000 hours;

The mean time between failures of a single function of the application software (APS) of the KPTS AIS should be at least 1500 hours;

The average recovery time of the KPTS AIS should be no more than 30 minutes; wherein:

The average recovery time of the KPTS after failures of technical means should be - no more than 20 minutes, excluding the time of organizational downtime;

The average recovery time of the KPTS after a failure of the general or special AIS software is no more than 20 minutes, excluding organizational downtime;

The average recovery time of a single communication channel of the KPTS should be no more than 3 hours;

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

12.1. A list of design stages for the LAN configuration, indicating the design decisions made.

12.2. Functional diagram LAN (LAN drawing indicating the brands of equipment and communication lines). In the scheme, it is recommended to note the number of workstations in different LAN segments, possible expansion reserves and bottlenecks.

12.3. The results of LAN cost calculations (to summarize in a table indicating the name, number of units, price and cost). When calculating the cost, take into account the costs of designing and installing the LAN.

Name	Quantity	Price	Note

12.4 Calculate the LAN delay and its reliability.

Annex 1.

Table 1

Comparative data on LAN characteristics

Characteristic	Qualitative assessment of characteristics
Bus and tree network	Ring network	star network
Response time tres.	In the marker tire tres. predictable and depends on the number of network nodes. In a random bus t resp. load dependent	tres. There is a function of the number of network nodes	totv. depends on the load and time characteristics of the central node
Bandwidth WITH	In a token bus, it depends on the number of nodes. In a random bus WITH increases with sporadic light loads and falls with long messages in stationary mode	WITH crashes when new nodes are added	WITH depends on the performance of the central node and the bandwidth of subscriber channels
Reliability	AC failures do not affect the performance of the rest of the network. A break in the cable disables the bus LAN.	The failure of one AS does not lead to the failure of the entire network. However, the use of bypass schemes allows you to protect the network from AC failures.	AC failures do not affect the performance of the rest of the network. The reliability of the LAN is determined by the reliability of the central node

To LAN Link Parameter Set include: bandwidth and data rate, point-to-point, multipoint and/or broadcast capability (i.e. allowed applications), maximum extension and number of connected subscriber systems, topological flexibility and installation complexity, interference immunity and cost.

The main problem lies in the simultaneous performance, for example, the highest data transfer rate is limited by the maximum possible data transfer distance, which still provides the required level of data protection. Easy scalability and ease of expansion of the cable system affect its cost.

Physical location conditions help determine the best cable type and topology. Each type of cable has its own maximum length limits: twisted pair provides work on short stretches, single channel coaxial cable - over long distances, multichannel coaxial and fiber optic cable - over very long distances.

The data transfer rate is also limited by the capabilities of the cable: the highest fiber optic, then go single-channel coaxial, multi-channel cables And twisted pair. Available cables can be selected according to the required characteristics.

fast ethernet 802.3u is not an independent standard, but is an addition to the existing 802.3 standard in the form of chapters. New technology Fast Ethernet retained all MAC level of classical ethernet, but the throughput has been increased to 100 Mbps. Therefore, since the throughput has increased by a factor of 10, the bit interval has decreased by a factor of 10, and is now 0.01 μs. Therefore, in technology Fast ethernet the minimum length frame transmission time in bit intervals remained the same, but equal to 5.75 µs. Restriction on the total length of the network fast ethernet decreased to 200 meters. All technology differences fast ethernet from ethernet focused on the physical level. Levels MAC And LLC V fast ethernet remained exactly the same.

The official 802.3u standard established three different specifications for the physical layer fast ethernet:

- 100Base-TX- for two-pair cable on unshielded twisted pair UTP category 5 or shielded twisted pair STP Type 1;

- 100Base-T4- for a four-pair cable on an unshielded twisted pair UTP category 3, 4 or 5;

100Base-FX - for multi-mode fiber optic cable, two fibers are used.

IN ethernet 2 classes of concentrators are introduced: 1st class and 2nd class. Class 1 hubs support all types of physical layer encoding ( TX, FX, T4), i.e. ports can be different. Class 2 hubs only support one type of physical layer encoding: either TX/FX, or T4.

Maximum distances from the hub to the node:

- TX- 100 m, FX– multimode: 412 m (half duplex), 2 km (full). Singlemode: 412 m (half duplex), up to 100 km (full), T4- 100 m.

There can be only one class 1 concentrator in the network, two class 2 concentrators, but their m / d is 5 m.

Twisted Pair (UTP)

The cheapest cable connection is a two-wire twisted-wire connection, often referred to as twisted pair (twisted pair). It allows you to transfer information at speeds up to 10-100 Mbit / s, it can be easily increased, but it is noise-immune. The cable length cannot exceed 1000 m at a transmission rate of 1 Mbps. The advantages are low price and easy installation. To increase the noise immunity of information, a shielded twisted pair is often used. This increases the cost of twisted pair and brings its price closer to the price of coaxial cable.

1. A traditional telephone cable that can carry voice but not data.

2. Capable of transmitting data at speeds up to 4 Mbps. 4 twisted pairs.

3. A cable capable of transmitting data at speeds up to 10 Mbps. 4 twisted pair with nine turns per meter.

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

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

6. The cable, capable of transmitting data at speeds up to 1 Gb / s, consists of 4 twisted pairs.

Coaxial cable has an average price, is noise-proof and is used for communication over long distances (several kilometers). The information transfer rate is from 1 to 10 Mbps, and in some cases it can reach 50 Mbps. Coaxial cable used for basic and broadband transmission of information.

Broadband coaxial cable immune to interference, easy to build up, but its price is high. The information transfer rate is 500 Mbps. When transmitting information in the baseband over a distance of more than 1.5 km, an amplifier is required, or the so-called repeater ( repeater). Therefore, the total distance during the transmission of information increases to 10 km. For computer networks with a bus or tree topology, the coaxial cable must have a terminating resistor (terminator) at the end.

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

Cheaper than ethernet-cable, is a connection cheapernet-cable or, as it is often called, thin (thin) ethernet. It is also a 50-ohm coaxial cable with a transmission rate of 10 million bps.

When connecting segments cheapernet-cable repeaters are also required. Computing networks with cheapernet-cable have a low cost and minimal costs for building. Network boards are connected using widely used small-sized bayonet connectors ( SR-50). Additional shielding is not required. The cable is connected to the PC using tee connectors ( Tconnectors). The distance between two workstations without repeaters can be a maximum of 300 m, and the total distance for the network is Cheapemet- cable - about 1000 m. Transceiver cheapernet is located on the network board and is used both for galvanic isolation between adapters and for amplifying an external signal.

The most expensive are optoconductors, also called fiberglass cable. The speed of dissemination of information through them reaches several gigabits per second. There is practically no external influence of interference. They are used where electromagnetic interference fields occur or where information is required to be transmitted over very long distances without the use of repeaters. They have anti-eavesdropping properties, since the tapping technique in fiber optic cables is very complex. Optical conductors are combined into a LAN using a star connection.

2 types of fiber:

1)single mode cable- a central conductor of small diameter is used, commensurate with the wavelength of light (5-10 microns). In this case, all light rays propagate along the optical axis of the fiber without being reflected from the outer conductor. As a laser is used. Cable length - 100 km or more.

2) multi-mode cable - use wider inner cores (40-100 microns). In the inner conductor, several light rays simultaneously exist, reflecting from the outer conductor at different angles. Reflection angle beam mode. LEDs are used as a source of radiation. Cable length - up to 2 km.

BIBLIOGRAPHY

network olifer. Principles, technologies, protocols. - St. Petersburg: Peter, 20s.

Guk, M. Hardware of local networks. Encyclopedia. - St. Petersburg. : Publishing house Peter, 2004 .- 576 p.

Novikov, networks: architecture, algorithms, design. - M. : ECOM, 2002 .- 312p. : ill. ; 23cm - ISBN-8.

Epaneshnikov, computer networks /, .- Moscow: Dialogue-MEPhI, 2005 .- 224 p.

1. http://*****/, system for automatic creation projects of local computer networks
Compiled by: Nikolai Mikhailovich Dubinin

Ruslan Nikolaevich Agapov

Gennady Vladimirovich Startsev

LOCAL NETWORK DESIGN

Laboratory workshop on the discipline

"Computer networks and telecommunications"

Signed for publication xx.05.2008. Format 60x84 1/16.

Offset paper. The print is flat. Times New Roman typeface.

Conv. oven l. . Conv. cr. - Rev. . Uch. - ed. l. .

Circulation 100 copies. Order No.

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