Do-it-yourself local network. Detailed instructions from the system administrator

Practical work № 23-24

Subject: The local network. Topologies of local networks.

Goal of the work: apply in practice knowledge about the purpose, principles of construction and operation of local computer networks.

Theoretical information

local computer network This is a set of software and devices that unite subscribers located at a small distance from each other. As a rule, such systems are used within the boundaries of one enterprise or building.

Types of local networks

These lines are usually divided into 2 types:

Networks characterized by centralized management, characterized by a common security policy applicable to all users

peer-to-peer networks. In such a system, all users independently determine what information and resources they will provide for public use. And computers are completely equal and can be both a client and a server at the same time.

The main tasks of local computer networks

the main tasklocal computer network is the implementation of shared access of all users to data, devices and programs. Thus, the clients of the system can perform operations simultaneously, rather than one by one.

In addition, local lines solve the following issues:

Data processing and storage;

Transfer of information results to users;

Project execution control.

Main Ingredients local network

A local computer network cannot fully function without special equipment. For her, the main components are:

Passive equipment: patch panels, mounting cabinets, information sockets, cables, cable channels;

Peripherals and computers: printers, servers, workstations, scanners;

Active equipment: routers, switches (switches), special media convectors.

Depending on how the network will be built, how long and according to what requirements, the set of devices during installation can vary significantly.

Benefits of using a local network

This type of system solves many computational and information tasks within the same enterprise. Therefore, for an organization, a local type computer network is necessary due to several of its advantages:

The system ensures that all personal data is stored on the disk of the file server. This makes it possible to work simultaneously with all clients, update data in network software products and at the same time use information protected at the level of files and directories.

The local network facilitates the exchange of information between all computers in the system.

Each client has access to global network subject to the presence of a special switching node.

Such a computer network provides a full-fledged printing of information by all users on public printers.

The local system allows you to store software products ( graphic editor, tables, database management systems) on the disks of the file server in a single copy.

Requirements for local area networks

CurrentlyIT companiesa large number of local area networks have been created, which differ in operation algorithms, organization structure, topologies, and sizes. They are operated in different countries of the world, but the requirements for them are generally accepted.

Reliability. One of the main properties, aimed at maintaining full and partial functioning in the event of a breakdown of several nodes.

Speed. The most important property, characterized by the presence of high-speed data transmission channels.

Adaptation. A property of a local area network aimed at expansion: workstations are installed in the place where it is required.

A local network is an important element of any modern enterprise, without which it is impossible to achieve maximum labor productivity. However, in order to take full advantage of networking, it must be properly configured, also bearing in mind that the location of the connected computers will affect the performance of the LAN.

The concept of topology The topology of local computer networks is the location of workstations and nodes relative to each other and their connection options. In fact, this is a LAN architecture. The placement of computers determines the technical characteristics of the network, and the choice of any kind of topology will affect:

Varieties and characteristics network equipment.

Reliability and scalability of the LAN.

A way to manage a local network.

There are many such options for the location of work nodes and ways to connect them, and their number increases in direct proportion to the increase in the number of connected computers. The main LAN topologies are star, bus, and ring.

Factors to consider when choosing a topology

D
Before finally deciding on the choice of topology, it is necessary to take into account several features that affect the performance of the network. Based on them, you can choose the most suitable topology, analyzing the advantages and disadvantages of each of them and correlating these data with the conditions available for installation.

Operability and serviceability of each of the workstations connected to the LAN. Some kinds of LAN topology depend entirely on this.

Healthy equipment (routers, adapters, etc.). Failure of network equipment can either completely disrupt the operation of the LAN or stop the exchange of information with one computer.

The reliability of the cable used. Damage to it disrupts the transmission and reception of data throughout the LAN or in one of its segments.

Cable length limitation. This factor is also important when choosing a topology. If there is not much cable available, you can choose a layout that requires less cable.

About star topology

This type of location of workstations has a dedicated center - a server to which all other computers are connected. It is through the server that data exchange processes take place. Therefore, its equipment should be more complex.

D
advantages:

The topology of local networks "star" compares favorably with others by the complete absence of conflicts in the LAN - this is achieved through centralized management.

Failure of one of the nodes or damage to the cable will not have any effect on the network as a whole.

The presence of only two subscribers, the main and peripheral, allows you to simplify the network equipment.

The accumulation of connection points in a small radius simplifies the process of network control, and also improves its security by restricting access to outsiders.

Flaws:

Such a local network in the event of a failure of the central server becomes completely inoperable.

The cost of a "star" is higher than other topologies, since much more cable is required.

Bus topology: simple and cheap

IN
In this connection method, all workstations are connected to a single line - coaxial cable, and data from one subscriber is sent to the rest in the half-duplex exchange mode. Local area network topologies of this kind require the presence of a special terminator at each end of the bus, without which the signal is distorted.

Advantages :

All computers are equal.

The ability to easily scale the network even during its operation.

The failure of one node does not affect the others.

Cable consumption has been significantly reduced.

Flaws:

Insufficient network reliability due to problems with cable connectors.

Low performance due to the division of the channel between all subscribers.

Complexity of control and troubleshooting due to parallel connected adapters.

The length of the communication line is limited, therefore these types of local network topologies are used only for a large number computers.

Characteristics of the ring topology

T What type of communication involves the connection of a working node with two others, data is received from one of them, and data is transmitted to the second. The main feature of this topology is that each terminal acts as a repeater, eliminating the possibility of signal attenuation in the LAN.Advantages:

Quickly create and configure this LAN topology.

Easily scalable, however, requiring the network to be shut down while a new node is being installed.

A large number of potential subscribers.

Overload tolerance and no network conflicts.

The ability to increase the network to a huge size by relaying the signal between computers.

Flaws:

The unreliability of the network as a whole.

Lack of resistance to cable damage, so a parallel redundant line is usually provided.

Large cable consumption.

Types of local networks

The choice of LAN topology should also be made based on the type of LAN available. The network can be represented by two models: peer-to-peer and hierarchical.

They do not differ much in functionality, which allows you to switch from one to another if necessary. However, there are still a few differences between them. With regard to the peer-to-peer model, its use is recommended in situations where the ability of the organization big network is absent, but the creation of some kind of communication system is still necessary. It is recommended to create it only for a small number of computers. Communication with centralized management is commonly used in various enterprises to control workstations.

peer-to-peer network

E
This type of LAN implies the equality of each workstation, distributing data between them. Access to information stored on a node can be allowed or denied by its user. As a rule, in such cases, the topology of local computer networks "bus" will be the most suitable.

Peer-to-peer network implies the availability of workstation resources to other users. This means the ability to edit a document on one computer while working on another, print remotely and run applications.

Advantages of a peer-to-peer LAN type:

Ease of implementation, installation and maintenance.

Small financial costs.

This model eliminates the need to purchase an expensive server.

Flaws:

Network performance decreases in proportion to the increase in the number of connected worker nodes.

Absent one system security.

Availability of information: when you turn off the computer, the data in it will become inaccessible to others.

There is no single information base.

Hierarchical model

The most commonly used LAN topologies are based on this type of LAN. It is also called "client-server". The essence of this model is that in the presence of a certain number of subscribers, there is one main element - the server. This control computer stores all data and processes them.

Advantages:

Excellent network performance.

A single reliable security system.

One, common for all, information base.

Easier management of the entire network and its elements.

Flaws:

The need for a special personnel unit - an administrator who monitors and maintains the server.

Large financial costs for the purchase of a host computer.

The most commonly used configuration (topology) of a local computer network in a hierarchical model is a "star".

The choice of topology (the layout of network equipment and workstations) is an extremely important point in organizing a local network. The selected type of communication should provide the most efficient and safe work LAN. It is also important to pay attention to financial costs and the possibility of further expansion of the network. Finding a rational solution is not an easy task, which is accomplished through careful analysis and a responsible approach. It is in this case that correctly selected topologies of local networks will ensure maximum performance of the entire LAN as a whole.

Exercise 1

Describe a peer-to-peer LAN with a linear bus topology.

Fill the table.

Local network diagram

Flaws

Advantages

equipment

price

Conclusions:

Task 2

Describe a peer-to-peer LAN with a star topology.

Analyze the description of the local network and draw conclusions.

Fill the table.

Local network diagram

Flaws

Advantages

Number of computers on the network

Equipment required to create a network and its cost

equipment

price

The total cost of creating a local network

Conclusions:

Task 3

Describe a local area network based on a server.

Analyze the description of the local network and draw conclusions.

Fill the table

Local network diagram

Flaws

Advantages

Number of computers on the network

Equipment required to create a network and its cost

equipment

price

The total cost of creating a local network

Conclusions:

Large companies have in circulation a large amount of data of a different nature:

• text files;
• graphic;
• Images;
• tables;
• scheme.

For management, it is important that all information has a convenient format, is easily converted and transmitted on any medium to the right hands. But paper documents have long begun to be replaced by digitized ones, since a computer can contain a lot of data that is much more convenient to work with using process automation. This is also facilitated by the transfer of information, reports and contracts to partners or inspection companies without long journeys.

So there was a need for the widespread supply of departments of firms with electronic computing devices. Along with this, the question arose of combining these devices into a single complex for the protection, safety and convenience of moving files.

In this article, we will tell you how to facilitate the design of a local computer (computer) network in an enterprise.

What is a LAN, its functions

This is a connecting connection of a number of computers in one closed space. Often this method is used in large companies, in production. You can also independently create a small connection of 2 - 3 devices, even at home. The more inclusions in the structure, the more complex it becomes.

Types of networking

There are two types of connection, they differ in complexity and the presence of a leading, central link:

• Equal.
• Multilevel.

Equivalent, they are peer-to-peer, characterized by similarity in technical specifications. They have the same distribution of functions - each user can access all general documents, perform the same operations. Such a scheme is easy to manage, it does not require multiple efforts to create it. The downside is its limitedness - no more than 10 members can join this circle, otherwise the overall efficiency of work and speed are violated.

Server design of a company's local network is more laborious, however, such a system has a higher level of information protection, and there is also a clear distribution of responsibilities within the web. The best in terms of technical characteristics (powerful, reliable, with more RAM) computer is assigned as a server. This is the center of the entire LAN, all data is stored here, from the same point you can open or stop access to documents to other users.

Functions of computer networks

The main properties to consider when drafting a project:

• Connectivity additional devices. Initially, there may be several machines in the grid, with the expansion of the company, additional inclusion may be required. When calculating the power, you should pay attention to this, otherwise you will need to redevelop and buy new consumables of increased strength.
• Adaptation for different technologies. It is necessary to ensure the flexibility of the system and its adaptability to different network cables and different software.
• Availability of redundant lines. First, it refers to the exit points of ordinary computers. In case of failure, it should be possible to connect another cord. Secondly, you need to ensure the uninterrupted operation of the server with a multi-level connection. You can do this by ensuring automatic failover to the second hub.
• Reliability. Equipped with uninterruptible power supplies, autonomous energy reserves to minimize the possibility of communication interruption.
• Protection from outside influences and hacking. Stored data can be protected not just with a password, but with a whole bunch of devices: a hub, a switch, a router, and a remote access server.
• Automated and manual control. It is important to install a program that will analyze the state of the grid at every moment of time and notify you of malfunctions so that they can be quickly eliminated. An example of such software is RMON. At the same time, personal monitoring via Internet servers can also be used.

Drawing up technical requirements for the design and calculation of a local area network (LAN) in an enterprise

From the properties come the conditions that must be taken into account when drawing up a project. The entire design process begins with the preparation of technical specifications (TOR). It contains:

• Data security standards.
• Providing all connected computers with access to information.
• Performance parameters: response time from user request to opening desired page, throughput, that is, the amount of data in operation and the transmission delay.
• Reliability conditions, that is, readiness for long-term, even permanent work without interruption.
• Replacement of components - expansion of the grid, additional inclusions or installation of equipment of a different power.
• Support for different types of traffic: text, graphics, multimedia content.
• Providing centralized and remote control.
• Integration of various systems and software packages.

When the TOR is compiled in accordance with the needs of users, the type of inclusion of all points in one network is selected.

Basic LAN topologies

These are ways to physically connect devices. The most frequent are represented by three figures:

• tire;
• ring;
• star.

Busbar (linear)

When assembling, one lead cable is used; wires to user computers already depart from it. The main cord is directly connected to the server that stores the information. It also selects and filters data, provides or restricts access.

Advantages:

• Disabling or problems with one element does not break the rest of the grid.
• Designing an organization's LAN is fairly straightforward.
• Relatively low cost of installation and consumables.

Flaws:

• A failure or damage to the carrier cable brings the entire system to a halt.
• A small area can be connected in this way.
• Performance can suffer from this, especially if the connection passes between more than 10 devices.

"Ring" (ring)

All user computers are connected in series - from one device to another. This is often done in the case of peer-to-peer LANs. In general, this technology is used less and less.

Advantages:

• No hub, router or other network equipment costs.
• Multiple users can send information at once.

Flaws:

• The transfer rate in the whole mesh depends on the power of the slowest processor.
• If there is a problem in the cable or if any element is not connected, the general work stops.
• Setting up such a system is quite difficult.
• When connecting an additional workplace, it is necessary to interrupt the general activity.

"Star"

This is a parallel connection of devices to the network to a common source - the server. As a cent, a hub or concentrator is most often used. All data is transmitted through it. In this way, not only computers can work, but also printers, fax machines and other equipment. In modern enterprises, this is the most frequently used method of organizing activities.

Advantages:

• It is easy to connect another place.
• Performance does not depend on speed individual elements, therefore remains at a stable high level.
• Just find the break.

Flaws:

• A malfunction of the central unit terminates the activity of all users.
• The number of connections is determined by the number of ports on the server device.
• The network consumes a lot of cable.
• Expensive equipment.

Stages of LAN software design

This is a multi-stage process that requires the competent participation of many specialists, since it is necessary to pre-calculate the necessary throughput cables, take into account the configuration of the premises, install and configure equipment.

Organization space planning

The offices of workers and superiors should be arranged in accordance with the chosen topology. If the star shape suits you, then you should place the main technique in the room that is the main one and is located in the center. It could also be the management's office. In the case of bus distribution, the service may be located in the most remote room along the corridor.

Building a local network diagram

The drawing can be made in specialized computer-aided design programs. ZVSOFT products are ideal - they contain all the basic elements that will be required during construction.

The network should take into account:

• maximum voltage;
• sequence of occurrences;
• possible interruptions;
• cost-effectiveness of the installation;
• convenient power supply.

The characteristics of the LAN must be selected in accordance with the layout of the premises of the organization and the equipment used.

Computer and network device settings

When choosing and purchasing mesh elements, it is important to consider the following factors:

• Compatible with different programs and new technologies.
• Data transfer rate and device performance.
• The quantity and quality of cables depends on the chosen topology.
• Method of managing exchanges in the network.
• Protection against interference and failures by winding wires.
• The cost and power of network adapters, transceivers, repeaters, hubs, switches.

Principles of designing a LAN using computer programs

When drawing up a project, it is important to take into account a large number of nuances. The software from ZWSOFT will help with this. The company develops and sells multifunctional software to automate the work of design engineers. Basic CAD is similar to the popular but expensive package from Autodesk - AutoCAD, but surpasses it in ease and convenience of licensing, as well as in a more loyal pricing policy.

Benefits of the program:

• intuitive, user-friendly interface in black.
• Wide selection of tools.
• Work in two-dimensional and three-dimensional space.
• 3D visualization.
• Integration with most popular file extensions.
• Organization of LAN elements in the form of blocks.
• Counting the lengths of cable lines.
• Visual arrangement of elements and nodes.
• Simultaneous work with graphics and text data.
• Ability to install additional applications.

For ZWCAD - a module that extends the functions of the basic CAD in the field of multimedia circuit design. All drawings are made with automated calculation of LAN cables and their marking.

Advantages:

• automation of selection of switching systems;
• wide library of elements;
• parallel filling of the cable magazine;
• automatic creation of specifications;
• adding equipment to the library;
• simultaneous work of several users with the database;
• schematic marks for the location of devices and pieces of furniture.

It will help to make a project in a three-dimensional form, create it in 3D. Intelligent tools allow you to quickly lay LAN routes to connection points, visualize the places where cables pass, organize line intersections, make cuts of connected equipment and technological furniture (including in dynamic mode). Using the component editor, you can create a library of cabinets, switching devices, cables, clamps, etc., as well as assign characteristics to them, on the basis of which you can later create specifications and calculations. Thus, the functions of this software will help complete the master plan of the premises of the organization with the tracing of all LAN lines.

Create a local area network project in your enterprise together with programs from ZVSOFT.

A structured cabling system is a set of switching elements (cables, connectors, cross panels and cabinets), as well as a technique for sharing them, which allows you to create regular, easily expandable communication structures in computer networks.

A structured cabling system is a kind of "constructor", with the help of which the network designer builds the configuration he needs from standard cables connected by standard connectors and switched on standard cross panels. If necessary, the connection configuration can be easily changed - add a computer, segment, switch, remove unnecessary equipment, and also change the connections between computers and switches.

When building a structured cabling system, it is understood that every workplace in the enterprise must be equipped with sockets for connecting a phone and a computer, even if this is not needed at that moment. That is, a good structured cabling system is built redundant. This can save money in the future, since changes to the connection of new devices can be made by reconnecting already laid cables.

According to the task, the block diagram of the location of buildings, each of which has its own subnet, is shown in Fig. 2.1.

Figure 2.1 - Block diagram of the location of buildings

The block diagram of the subnetworks of each of the buildings is shown in fig. 2.2 - 2.3. Since there are two 5-storey buildings, and they have the same number of switching equipment and PCs, their block diagrams are identical.

Figure 2.2 - Structural diagram of the subnetwork of a 5-storey building

Figure 2.3 - Structural diagram of the subnetwork of a 4-storey building

The block diagram of connecting subnets into one network is shown in fig. 2.4.

Figure 2.4 - General block diagram of the network

In buildings, the technology is FastEthernet, between buildings - FDDI, Internet access from each building via a radio channel.

3 Equipment and cable selection

3.1 Switch selection

A switch is a device designed to connect several nodes of a computer network within one or more network segments. The switch operates at the data link layer of the OSI model. Unlike a hub that distributes traffic from one connected device to all others, a switch only forwards data directly to the recipient. This improves network performance and security by eliminating the need for other segments of the network to process data that was not intended for them.

In this course project, in each room of the buildings there are room switches - workgroup switches, on each floor - a floor switch that combines workgroup switches on its floor, and a root switch located in the server room on the first floor, to which the switches of all floors are connected.

Switching equipment (switches, routers) was selected from the manufacturer Cisco. According to the Dell "Oro Group, Cisco occupies 60% of the global network equipment market, that is, more than all other competitors. This manufacturer has the widest line of all network solutions, a wide range of technologies, protocols, ideologies, both standard and and our own, allowing you to expand the capabilities of the network, the broadest troubleshooting capabilities built into almost all Cisco devices.

Based on the optimal ratio of price, performance and functionality, the following models of switches were selected, belonging to the Cisco 300 series, designed specifically for small businesses. The line includes a range of low cost managed switches that provide a powerful foundation for maintaining a corporate network.

Cisco 300 Series Switch Features

provide the high availability and performance needed for mission-critical business applications while minimizing potential downtime.

allow you to control network traffic using modern features such as quality of service analysis, static routing of the third layer, support for the IPv6 protocol.

have clear tools with a web interface; the possibility of mass deployment; similar functions in all models.

allow you to optimize energy consumption without affecting performance.

3.1.1 Workgroup switches

According to the assignment for coursework in a 4-storey building in three rooms on each floor there are 35 computers, and in two 5-storey buildings in one room on each floor there are 31 computers, for the connection of which the SG300-52 switch with 48 ports is selected (Fig. 3.1).

Figure 3.1 - Workgroup switch SG300-52

Switch SG300-52 (price: 7522 UAH), manufactured by Cisco, is equipped with 48 10/100/1000 Mbps ports for Ethernet networks with automatic speed negotiation for RJ45 ports, which facilitates installation of the device.

This switch provides good performance and can improve workgroup performance and network and host throughput, ensuring easy and flexible installation and configuration. Due to the compact size of the body, the device is ideal for placement on a limited desktop space; also the device can be mounted in a rack. Dynamic LEDs display the switch's real-time status and allow basic diagnostics of the device's operation.

The main technical characteristics of the SG300-52 switch are presented in Table 3.1.

Table 3.1 - Technical characteristics of the switch SG300-52

	managed switch
Interface	4 x SFP (mini-GBIC), 48 x Gigabit Ethernet (10/100/1000 Mbps)
	SNMP 1, RMON 1, RMON 2, RMON 3, RMON 9, Telnet, SNMP 3, SNMP 2c, HTTP, HTTPS, TFTP, SSH,
Routing protocol	Static IPv4 routing, 32 routes
MAC address table	16000 entries
	128 MB (RAM), Flash memory - 16 MB
Encryption algorithm
Additional features	Up to 32 static routes and up to 32 IP interfaces DHCP layer 3 translation User Datagram Protocol (UDP) translation Smartports feature simplifies configuration and security management Built-in configuration utility, web-based access (HTTP/HTTPS) Dual stack IPv6 and IPv4 protocols Upgradable software
Supported standards	IEEE 802.3 10BASE-T Ethernet, IEEE 802.3u 100BASE-TX Fast Ethernet, IEEE 802.3ab 1000BASE-T Gigabit Ethernet, IEEE 802.3ad LACP, IEEE 802.3z Gigabit Ethernet, IEEE 802.3x Flow Control, IEEE 802.1D (STP, GARP, and GVRP),IEEE 802.1Q/p VLAN, IEEE 802.1w RSTP, IEEE 802.1s Multiple STP, IEEE 802.1X Port Access Authentication, IEEE 802.3af, IEEE
	Internal power supply. 120-130VAC, 50/60Hz, 53W.
Surrounding conditions. environments	Operating temperature: 0°C ~40°C
Dimensions (WxDxH)	440*260*44mm

For two 5-storey buildings, which have 18 and 25 computers in the remaining rooms on each floor, respectively, 18 computers are selected for connection - a switch for 24 ports - SF300-24P (price: 4042 UAH), and for connection 25 computers - two switches, each for 16 ports - SG300-20 (price: UAH 3023), which are shown in fig. 3.2. The remaining ports are reserved.

Figure 3.2 - Workgroup switch SF300-24P (a) and SG300-20 (b)

The SF300-24P is a 24-port managed network switch. These switches provide all the features you need to run mission-critical business applications, protect sensitive information, and optimize bandwidth for more efficient network transmission. Plug-and-play and auto-negotiation support allow the switch to automatically detect the type of connected device (for example, network adapter Ethernet) and choose the most appropriate speed. LED indicators are used for cable connection control and standard diagnostics. The switch can be desktop-mounted or rack-mounted.

Designed for small workgroups, the SG300-20 is equipped with 18 Ethernet ports 10/100/1000BASE-TX and 2 mini-GBICs. The functionality of these switches is similar to the functionality of the SF300-24P switch, since they both belong to the same Cisco 300 series.

The main technical characteristics of the SF300-24P switch are presented in table 3.2, and the SG300-20 switch - table. 3.3.

Table 3.2 - Technical characteristics of the SF300-24P switch

	managed switch
Interfaces	24 Ethernet 10Base-T/100Base-TX ports - RJ-45 connector, PoE support; console control port - 9 pin D-Sub (DB-9); 4 Ethernet ports 10Base-T/100Base-TX/1000Base-T - RJ-45 connector, 2 port for SFP (mini-GBIC) modules.
Remote Administration Protocol
Routing protocol	Static IPv4 routing
MAC address table	16000 entries
	128 MB (RAM), Flash memory - 16 MB
Encryption algorithm
Control	SNMP version 1, 2c, and 3 Built-in RMON software agent for traffic management, monitoring, and analysis Dual-stack IPv6 and IPv4 protocols Software updates DHCP port mirroring (options 66, 67, 82, 129, and 150) Smartports feature simplifies configuration and security management Cloud-based services Other management functions: Traceroute; management through a single IP address; HTTP/HTTPS; SSH RADIUS; DHCP client; BOOTP; SNTP xmodem update; cable diagnostics; ping; syslog; Telnet client (SSH support)
Supported standards	IEEE 802.3 10BASE-T Ethernet IEEE 802.3u 100BASE-TX Fast Ethernet IEEE 802.3ab 1000BASE-T Gigabit Ethernet IEEE 802.3ad LACP IEEE 802.3z Gigabit Ethernet IEEE 802.3x Flow Control IEEE 802.1D (STP, GARP, and GVRP) IEEE 802.1Q /p VLAN IEEE 802.1w RSTP IEEE 802.1s Multiple STP IEEE 802.1X Port Access Authentication IEEE 802.3af IEEE 802.3at
Performance	Non-blocking switching at up to 9.52 Mpps (packet size 64 bytes) Switching matrix: up to 12.8 Gbps Packet buffer size: 4 MB
Availability	Automatic power off on RJ-45 Gigabit Ethernet ports when there is no connection, re-power on when activity resumes

Table 3.3 - Technical characteristics of the SF300-20 switch

	managed switch
Interfaces	18 Ethernet 10Base-T/100Base-TX ports - RJ-45 connector, 2 ports for SFP (mini-GBIC) modules.
Remote Administration Protocol	SNMP 1, RMON 1, RMON 2, RMON 3, RMON 9, Telnet, SNMP 3, SNMP 2c, HTTP, HTTPS, TFTP, SSH,
Routing protocol	Static IPv4 routing
MAC address table	16000 entries
	128 MB (RAM), Flash memory - 16 MB, buffer size - 1 MB
Encryption algorithm	802.1x RADIUS, HTTPS, MD5, SSH, SSH-2, SSL/TLS
Control protocols	IGMPv1/2/3, SNMPv1/2c/3
Supported standards	IEEE 802.1ab, IEEE 802.1D, IEEE 802.1p, IEEE 802.1Q, IEEE 802.1s, IEEE 802.1w, IEEE 802.1x, IEEE 802.3, IEEE 802.3ab, IEEE 802.3ad, IEEE 802.3at, IEEE 802.3u, IEEE 802.3x , IEEE 802.3z
Supported network protocols	IPv4/IPv6, HTTP, SNTP, TFTP, DNS, BOOTP, Bonjour
Functional	Flow control support Port mirroring Channel merging Jumbo Frame Support Broadcast storm control Speed ​​Limit DHCP client Spanning tree protocol, etc.
	Internal power supply. 120-130V alternating current, 50/60Hz, 53W.
Surrounding conditions. environments	Operating temperature: 0°C ~40°C

3.1.2 Floor switches

To connect workgroup switches, storey switches are used, for which the SRW208G-K9 switch (price: UAH 1483) is selected, which has 8 ports (Fig. 3.3).

Figure 3.3 - Floor switch SRW208G-K9

The SRW208G-K9 switch is equipped with 8 RJ45 ports for Fast Ethernet, 1 Gigabit Ethernet port, and two SFP (mini-GBIC) ports that operate in auto-configuration and speed-sensing mode.

The Cisco Catalyst 2960 is a series of new Fixed Configuration Smart Ethernet Switches. They provide the need for data transmission at a speed of 100 Mbps and 1 Gbps, allow the use of LAN services, for example, for data transmission networks built in corporate branches. The Catalyst 2960 family delivers high data security with built-in NAC, QoS support, and a high level of system resiliency.

Key Features:

High security, advanced access control lists (ACLs);

Organization of network control and optimization of bandwidth using QoS, differentiated rate limiting and ACL.

To ensure network security, the switches use a wide range of user authentication methods, data encryption technologies and organization of access control to resources based on the user ID, port and MAC addresses.

Switches are easy to manage and configure

An auto-configuration feature is available via Smart ports for some specialized applications.

The main technical characteristics of this switch, manufactured by Cisco, coincide with the characteristics presented in Table. 3.2. for a switch from the same company.

3.1.3 Root switches

To connect floor switches, root switches are used, for which a switch was chosen in each building - SG300-20, which has 16 ports. This switch was also chosen as a switch of the working group, its description is presented in clause 3.1.1.

3.2 Selecting routers

A router (router) is a device that has at least two network interfaces and forwards data packets between different network segments, making forwarding decisions based on information about the network topology and certain rules set by the administrator.

Routers help reduce network traffic by dividing it into collision or broadcast domains, and by filtering packets. They are mainly used to connect networks. different types, often incompatible in architecture and protocols. Often, a router is used to provide access from a local network to the Internet, performing the functions of address translation and a firewall.

To connect buildings to one network, a router is used, which was chosen as Cisco 7507 of the 7500 series (price: UAH 121,360), which has the ability to connect an FDDI module (Fig. 3.4).

Figure 3.4 - Cisco 7507 Router

This router was chosen based on the ability to connect an FDDI module, the optimal price from the entire line of this series, and the fact that the Cisco 7500 series modular routers are the most powerful Cisco routers. They meet the highest requirements for modern data networks. The flexible modular architecture of this series of routers makes it possible to use them in large network nodes, choosing the best solutions.

The Cisco 7500 series consists of three models. The Cisco 7505 has one Route/Switch Processor (RSP1= Route/Switch Processor), one power supply, and four interface processor slots (5 slots in total). The Cisco 7507 and Cisco 7513, with seven and thirteen slots respectively, provide more bandwidth and can be configured with two RSP2s or PSP4s and a redundant power supply. Combined with the new, redundant CyBus, the Cisco 7507/7513 routers offer unsurpassed performance and reliability capabilities. This is achieved through a new, distributed multiprocessor architecture that includes three elements:

Integrated Routing and Switching Processor (RSP);

New Versatile Interface Processor (VIP);

New high-speed bus Cisco CyBus.

In a dual RSP (Integrated Routing and Switching Processor) configuration, the Cisco 7500 distributes functions between the primary and secondary RSP, increasing system performance, and if one of the processors fails, the other takes over all functions.

The Cisco 7507 Router is a modular router designed for the backbone of large networks and works with virtually all LAN and WAN technologies and all major network protocols.

The Cisco 7507 series supports a very wide range of connections, including: Ethernet, Token Ring, FDDI, Serial, HSSI, ATM, Channelized T1, Fractionalized E1 (G.703/G.704), ISDN PRI, Channel Interface for IBM mainframes.

The network interfaces reside on modular processors that provide a direct connection between the high-speed Cisco Extended Bus (CxBus) backbone and the external network. Seven slots are available for front-end processors on the Cisco 7507. Hot-swap capability allows you to add, replace, or remove CxBus processor modules without interrupting network operation. For storage of information standard Flash-memory is used. All models come with a standard 19" rack mount kit.

There are such communication interface modules:

Ethernet Intelligent Link Interface - 2/4 Ethernet ports with high-speed filtering (29000 p/s), support for Transparent Bridging and Spanning Tree algorithms, configurable using the Optivity system;

Token Ring Intelligent Link Interface - 2/4 Token Ring 4/16 Mb/s ports;

FDDI Intelligent Link Interface - 2 ports supporting two SAS connections or one DAS connection, filtering at up to 500,000 p/s;

ATM Intelligent Link Interface.

3.3 Cable selection

Cable - a structure of one or more conductors (cores) isolated from each other, or optical fibers enclosed in a sheath. In addition to the actual cores and insulation, it may contain a screen, power elements and other structural elements. The main purpose is the transmission of a high-frequency signal in various fields of technology: for cable television systems, for communication systems, aviation, space technology, computer networks, household appliances etc. When using switches, the Fast Ethernet protocol can operate in duplex mode, in which there are no restrictions on the total length of the network, but there are restrictions on the length of the physical segments connecting neighboring devices (switch-adarter and switch-switch).

According to the assignment, Fast Ethernet technology with 100Base-TX specification was used inside the buildings, unshielded twisted pair (UTP) of category 5 was used as a communication line.

Between buildings - FDDI technology, as a communication line is used

optical cable for outdoor installation.

Indoor UTP cable, 2 pairs, category 5, is used in subscriber wiring when providing access to data network services. For laying, a cable from the manufacturer Neomax - NM10000 (Fig. 3.4) was chosen due to its high strength and long service life, its characteristics are presented in table 3.4.

Figure 3.4 - UTP, 2 pairs, cat. 5f: 1 - Outer shell; 2 - Twisted pair

Table 3.4 - Main characteristics of the UTP cable, cat.5

Conductor	electrolytic copper wire
core insulation	polyethylene high density
Conductor diameter (core)	0.51 mm (24 AWG)
Sheathed conductor diameter	0.9±0.02mm
External diameter (size) of the cable
Outer shell thickness
Color twisted pair:	blue-white/blue, orange-white/orange
Cable bending radius:	4 external cable diameters
Working temperature:	20°C - +75°C

3.4 Selecting wireless equipment

Each building uses a radio channel to access the Internet. The Maximus Sector 515812-B directional antenna was chosen as the antenna on the BPS (Fig. 3.5, a), and on the buildings, the TP-Link TL-WA7510N WiFi access point was selected as an external access point (Fig. 3.5, b). This equipment was chosen for the optimal ratio of price and functionality.

The 5GHz frequency band was chosen as the operating range, since the 2.4GHz band is more saturated (loaded) due to the ubiquity of wireless networks. This frequency is used by: the old standard 802.11b, the recently departed 802.11g and 802.11n. Whether you are using 802.11b, 802.11g, or 802.11n, you are transmitting data over the same channel. Another disadvantage of 2.4 GHz is the presence of "side noise" in the wireless channel, which degrades the channel throughput, since it shares the spectrum with many other unlicensed devices - microwave ovens, mini-monitors, cordless phones, etc. Also, the number of used radio channels in the range 2.4GHz is limited. The 5 GHz band is less crowded and has more usable channels at the expense of a slightly shorter coverage area.

Figure 3.5 - Wireless equipment: a) antenna; b) hotspot

Model TL-WA7510N (price: 529 UAH) is a long-range outdoor wireless device operating in the 5 GHz frequency band and transmitting data wirelessly at speeds up to 150 Mbps. The device has a dual polarized antenna with a gain of 15 dBi, which is a key element for building Wi-Fi connections over long distances. It is designed to transmit a signal with radiation angles of 60 degrees horizontally and 14 degrees vertically, increasing the signal strength by concentrating the radiation in a given direction.

Thanks to the all-weather housing and the temperature resistance of the internal hardware, the access point can operate in various environmental conditions, in sunny or rainy weather, in strong winds or in snowfall. Built-in ESD protection up to 15KV and lightning protection up to 4000V can prevent power surges during a thunderstorm, which ensures the stability of the device. In addition, the device has a ground terminal for a more professional level of protection for some advanced users.

The device can work not only in the access point mode. The TL-WA7510N model also supports AP client router, AP router, bridge, repeater and client operating modes, which can greatly expand the application scope of the device, provide users with the most versatile product possible.

Powered by a PoE injector, an outdoor access point can use an Ethernet cable to simultaneously transmit data and electricity to wherever the access point is up to 60 meters away. This feature increases the placement options for the access point, allowing you to position the access point in the most suitable location for receiving best quality signal.

The main characteristics of the TL-WA7510N are presented in Table. 3.5.

Table 3.5 - Characteristics of TL-WA7510N

Interface	1x 10/100Mbps auto-sensing RJ45(Auto-MDI/MDIX, PoE) 1x external Reverse SMA connector 1x ground terminal
Wireless standards	IEEE 802.11a, IEEE 802.11n
	Dual polarized directional antenna, 15 dBi gain
Dimensions (WxDxH)	250 x 85 x 60.5 mm (9.8 x 3.3 x 2.4 inches)
Antenna Beam Width	Horizontal: 60° Vertical: 14°
	ESD protection 15 kV Lightning protection up to 4000 V Built-in earth terminal
Continuation of the table. 3.5
frequency range	5.180-5.240 GHz 5.745-5.825 GHz Note: Frequency varies by region or country.
Signaling rate	11a: up to 54 Mbps (dynamic) 11n: up to 150 Mbps (dynamic)
Sensitivity (reception)	802.11a 54 Mbps: -77 dBm 48 Mbps: -79 dBm 36 Mbps: -83 dBm 24 Mbps: -86 dBm 18 Mbps: -91 dBm 12 Mbps: -92 dBm 9Mbps: -93dBm 6Mbps: -94dBm	802.11n 150Mbps: -73dBm 121.5Mbps: -76dBm 108Mbps: -77dBm 81Mbps: -81dBm 54Mbps: -84dBm 40.5Mbps : -88dBm 27Mbps: -91dBm 13.5Mbps: -93dBm
Operating modes	Access Point Router Access Point Client Router (WISP Client) Access Point/Client/Bridge/Repeater
Wireless Security	Enable/disable SSID; MAC address filter 64/128/152-bit encryption WEP WPA/WPA2, WPA-PSK/WPA2-PSK(AES/TKIP)
Additional features	PoE support up to 60 meters 4-level LED indicator

Sector antenna Maximus Sector 515812-B (price: 991 UAH) of vertical polarization is made in an antenna housing made of UV-resistant plastic with cast aluminum bracket. High-quality materials allow the antenna to be used in harsh weather conditions. It can be used for small, medium and large base stations. The antenna gives out a strong and stable signal at medium and long distances. The main characteristics are presented in table. 3.6.

Table 3.6 - Technical characteristics of Maximus Sector 515812-B

Information flows in the enterprise LAN

Consider the organizational and staffing structure of the unit. The division is headed CEO enterprises. The unit consists of 4 departments, one of which is a specialized department of direct subordination to the head. Each department has a different number of departments under its control. In each department, in turn, employees serve according to the staff list.

All of the above is illustrated in Fig. 2.1.

Orders

Operative information

Reports

Rice. 1.1. Organizational structure of the unit

In total, 23 people are involved in the unit, each of which is supposed to be allocated a personal computer for use.

Network structure planning

Computer network

A computer network is a number of computers within a limited area (located in the same room, in one or more closely spaced buildings) and connected to a single communication line. Today, most computer networks are local area networks (Local-Area Networks) that are located within the same office building and are based on a client/server computer model. network connection consists of two computers participating in communication and a path between them. You can create a network using wireless technologies, but this is not widespread yet.

In the client/server model, network communication is divided into two areas: the client side and the server side. By definition, a client requests information or services from a server. The server, in turn, serves the client's requests. Often, each side in a client/server model can act as both a server and a client. When creating a computer network, there are various components to choose from that determine what software and hardware you can use to form your corporate network. A computer network is an integral part of today's business infrastructure, and a corporate network is just one of the applications used in it and, accordingly, should not be the only factor determining the choice of network components. The components necessary for the Intranet should be an addition to the existing network without leading to a significant change in its architectures.

Network management method

Each company formulates its own requirements for the network configuration, determined by the nature of the tasks to be solved. First of all, it is necessary to determine how many people will work in the network. From this decision, in essence, all subsequent stages of creating a network will depend.

The number of workstations directly depends on the expected number of employees. Another factor is the hierarchy of the company. For a company with a horizontal structure, where all employees must have access to each other's data, optimal solution is a simple peer-to-peer network.

A company built on the principle of a vertical structure, in which it is known exactly which employee and what information should have access, should focus on the more expensive version of the network - with a dedicated server. Only in such a network is it possible to administer access rights (Fig. 3.1).

3 to 5 workstations

Server installation required

Rice. 3.1 Selecting the type of network.

In this case, the enterprise has 23 workstations, which need to be combined into a corporate network. Moreover, they are grouped into the following groups:

§ director of the enterprise - 1 workstation;

§ Department of direct subordination - 2 workstations;

§ secretary - 1 workstation;

§ departments 1, 2 and 3 of the 2nd department with 3, 2 and 4 workstations, respectively;

§ departments 4 and 5 of the 3rd department, 3 and 4 workstations each;

§ department 6 of the 4th department - 3 workstations.

Following from the network type selection scheme, we can decide that in this case a server installation is required, since we have a vertical structure of the enterprise, that is, differentiated access to information.

One of the main stages of planning is the creation of a preliminary scheme. In this case, depending on the type of network, the question arises of limiting the length of the cable segment. This may not be significant for a small office, but if the network spans several floors of a building, the problem appears in a completely different light. In this case, it is necessary to install additional repeaters (repeater).

In the situation with the Shuttle-S enterprise, the entire network will be located on one floor, and the distance between the network segments is not so great that the use of repeaters is required.

Floor plan

The layout of the premises affects the choice of network topology much more strongly than it might seem at first glance (Fig. 3.2).

Rice. 3.2. Floor plan

After determining the location of the server installation, you can immediately determine how much cable is required.

Server hosting

Unlike setting up a peer-to-peer network, when building a LAN with a server, another question arises - where is the best place to install a server.

Several factors influence the choice of location:

§ due to the high noise level, it is desirable to install the server separately from other workstations;

§ it is necessary to provide constant access to the server for maintenance;

§ for reasons of information security, it is required to restrict access to the server;

Thus, the only possible place for installing the server was chosen, which does not require restructuring of the internal premises. It was decided to install the server in the checkout room, since only this room meets the requirements, that is, the noise level in the checkout room is minimal, the checkout room is isolated from others, therefore, access to the server will be limited (Figure 2.3). At the same time, it is more convenient to maintain the server at the cash desk, since when installing the server in the office of the director or deputy. the director's service will be difficult due to the performance of their official duties, and in the office of the personnel department, access to the server for unauthorized persons is not very difficult. Placing a server in computer science classrooms does not meet any condition.

Network architecture

Network architecture is the combination of topology, access method, and standards required to create a workable network.

The choice of topology is determined, in particular, by the layout of the room in which the LAN is deployed. Besides, great importance have the cost of acquiring and installing network equipment, which is an important issue for the company, the price range here is also quite large.

The star topology is a more productive structure, each computer, including the server, is connected by a separate cable segment to a central hub (HAB).

The main advantage of such a network is its resistance to failures that occur due to malfunctions on individual PCs or due to damage to the network cable.

Figure 3.3 shows the topology of an enterprise network.

Rice. 3.3 Enterprise network topology.

The most important characteristic information exchange in local networks are the so-called access methods (access methods), regulating the order in which the workstation gets access to network resources and can exchange data.

The abbreviation CSMA / CD hides the English expression "Carrier Sense Multiple Access with Collision Detection" (multiple access with carrier sense and collision detection). By using this method All computers get equal access to the network. Each workstation checks whether the channel is free before starting data transmission. At the end of the transmission, each workstation checks whether the sent data packet has reached the destination. If the answer is negative, the node repeats the data transmission/reception control cycle and so on until it receives a message about the successful reception of information by the addressee.

the Ethernet architecture that the enterprise network will use uses this particular access method.

The Ethernet specification was proposed by the Xerox Corporation in the late seventies. Later, Digital Equipment Corporation (DEC) and Intel Corporation joined this project. In 1982, the specification for Ethernet version 2.0 was published. Based on Ethernet, the IEEE 802.3 standard was developed by the IEEE.

Twisted-pair (10Base-T) cable technology is currently the most popular. Such a cable does not cause difficulties when laying.

A twisted-pair network, unlike thin and thick coax, is built on a star topology. To build a network using a star topology, you need large quantity cable (but the price of twisted pair is not high). Such a scheme also has an invaluable advantage - high fault tolerance. The failure of one or more workstations does not lead to the failure of the entire system. True, if the hub fails, its failure will affect all devices connected through it.

Another advantage this option is the ease of network expansion, since when using additional hubs (up to four in series), it becomes possible to connect a large number of workstations (up to 1024). When using unshielded twisted pair (UTP), the length of the segment between the hub and the workstation should not exceed 100 meters, which is not observed in the enterprise.

Network resources

The next important aspect of network planning is sharing network resources(printers, faxes, modems).

The listed resources can be used both in peer-to-peer networks and in networks with a dedicated server. However, in the case of a peer-to-peer network, its shortcomings are immediately revealed. To work with the listed components, they must be installed on a workstation or connected to it peripherals. When this station is disabled, all components and related services become unavailable for shared use.

In networks with a server, such a computer exists by definition. The network server never shuts down except for short maintenance shutdowns. Thus, round-the-clock access of workstations to network periphery is provided.

The enterprise has ten printers: in each separate room. The administration went to the expense to create the most comfortable working conditions for the team.

Now the question of connecting the printer to the LAN. There are several ways to do this.

1. Connect to a workstation.

The printer is connected to the workstation that is closest to it, as a result of which this workstation becomes the print server. The disadvantage of this connection is that when printing jobs are performed, the performance of the workstation decreases for a while, which will negatively affect the work of application programs when the printer is used intensively. Also, if the machine is turned off, the print server will become inaccessible to other hosts.

2. Direct connection to the server.

The printer is connected to the server's parallel port using a special cable. In this case, it is permanently available to all workstations. The disadvantage of this solution is due to the limitation in the length of the printer cable, which ensures correct data transfer. Although the cable can be run for 10 meters or more, it must be run in conduits or floors, which will increase networking costs.

3. Connect to the network through a special network interface.

The printer is equipped with a network interface and connects to the network as a workstation. The interface card acts as a network adapter, and the printer is registered to the server as a LAN node. Software server sends print jobs over the network directly to a connected network printer.

In networks with a bus topology, a network printer, like workstations, is connected to network cable using a T-connector, and when using a "star" - through a hub.

An interface card can be installed in most printers, but its cost is quite high.

4. Connect to a dedicated print server.

An alternative to the third option is to use specialized servers print. Such a server is a network interface arranged in a separate housing with one or more connectors (ports) for connecting printers. However, in this case, using a print server is impractical.

In our case, due to the unprofitability of installing a special network printer, buying a separate interface card for the printer, the most suitable way to connect a network printer is to connect to a workstation. This decision was also influenced by the fact that printers are located near those workstations that need the greatest printer.