Combining computers in a local network

The local network - consolidation of several computers located on short distance from each other (usually within the same building) for the joint solution of information, computing, educational and other tasks. In a small local network maybe 10-20 computers, in a very large one - order 1000.

Purpose of local networks
· sharing shared hardware (printer drives, modems)

· real-time data exchange

· Information system enterprises (institutions)

Organization of local networks.

Although there are many various ways combine computers, essentially there are two types computer networks: peer-to-peer network and client-server network.
peer-to-peer network is an association of equal computers. Typically, a peer-to-peer network unites no more than 10 computers and is organized in homes or small offices.

Client server network more common in organizations such as a school, business, or library rather than in the home. In this type of network, one computer, called the server, is the heart of the network. It stores information and resources and makes them available to other computers on the network. Other computers that use the network to obtain this information are called clients.

Client-server networks are the best option for networking more than ten computers. They are more expensive, but in cases where you need to store a large amount of information, this is the best choice.

Models of various network configurations

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Topologies of local networks

Local networks depending on the purpose and technical may have different configurations. General scheme The connection of computers in a local area network is called a network topology. Network topologies can be different. Most often, local networks can have a "bus" and "star" topology. In the first case, all computers are connected to one common cable (bus), in the second case, there is a special central device (hub), from which "beams" go to each computer, i.e. each computer is connected to its own cable.
IN tire topology, computers are connected to a common channel (bus) through which they can exchange messages.

The bus-type structure is simpler and more economical, since it does not require an additional device and consumes less cable. But it is very sensitive to cable system failures. If the cable is damaged in at least one place, then there are problems for the entire network. The fault location is difficult to locate.
IN radial topology ("star" topology) in the center there is a concentrator that sequentially communicates with subscribers and connects them with each other.

In this sense, the "star" is more stable. A damaged cable is a problem for one particular computer; it does not affect the operation of the network as a whole. No troubleshooting required
IN annular topology information is transmitted over a closed channel. Each subscriber is directly connected to the two closest ones, although in principle it is able to contact any subscriber in the network.

In a network having a "ring" type structure, information is transmitted between stations along the ring with hopping in each network controller. Reception is carried out through buffer drives made on the basis of random access memory devices, therefore, if one network controller fails, the operation of the entire ring may be disrupted. The advantage of the ring structure is the ease of implementation of devices, and the disadvantage is low reliability.
hybrid a topology is a combination of different topologies in a single network. For example, you can connect multiple star networks with a single cable.
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LAN equipment

How do computers communicate with each other?

The operation of the network is based on the fact that all elements of the equipment are connected to each other in one way or another. Every computer and equipment such as printers, scanners, laptop computers connected with cables of various sizes, satellite communications or telephone lines. Today there are even wireless network connecting computers using radio waves.
LAN equipment generally includes:
computers (servers and workstations);
network boards (adapters);
· channels of connection;
special devices that support the functioning of the network (routers, hubs, switches).
Each computer connects to the network using a network card - adapter.
TO network board connects network cable. If radio or infrared communication is used, no cable is required. In modern local networks, two types are most often used. network cables:
Unshielded twisted pair
fiber optic cable.
Typically, the choice of a cable for a network depends on the following indicators: the cost of installation and maintenance, the data transfer rate, the limitation on the amount of information transfer distance without additional repeater amplifiers (repeaters), data transfer security.
twisted pair is a set of eight wires twisted in pairs in such a way as to provide protection against electromagnetic interference.

Twisted pair is the cheapest type of cable. Twisted pair allows a maximum transmission rate of up to 10 Mbps. The cable length should not exceed 1000 meters, and the data transfer rate will not exceed 1 Mbps. Shielded twisted-pair cables are used to increase noise immunity. Each twisted-pair cable connects only one computer to the network, so a connection failure affects only that computer, which allows you to quickly find and fix problems.
fiber optic cables transmit data in the form of light pulses along glass wires. Fiber optic cables provide the highest transmission speed; they are more reliable because they are not subject to electromagnetic interference.
Optical cable is very thin and flexible, making it easier to transport than heavier copper cable. The data transfer rate over optical cable is hundreds of thousands of megabits per second, which is about a thousand times faster than over twisted pair wires.

An optical fiber line is the most expensive type of connection today, but the speed of information propagation in it reaches several gigabits per second with an allowable distance of up to 50 kilometers. At the same time, communication lines built on the use of optical fiber are practically insensitive to electromagnetic interference.
Where to "plug" the cable in the computer? You need an intermediate (interface) device, which is called a network card or network adapter, and in English speech NIC– Network Interface Controller.
Network adapter, or NIC, is an embedded device that allows you to connect your computer to a network. Each computer has software installed that allows it to communicate with other computers.

Wireless connection on radio waves can be used to organize networks within large premises where the use of conventional communication lines is difficult or impractical. In addition, wireless lines can connect remote parts of the local network at distances up to 25 km (subject to line of sight).
In addition to cables and network adapters, twisted-pair local area networks use other network devices - hubs, switches and routers.
concentrator(also called a hub) - a device that combines several (from 5 to 48) branches of a star-shaped local network and transmits information packages in all branches of the network equally.

Switch(switch) does the same, but, unlike the hub, ensures the transfer of packets to the specified branches. This ensures the optimization of data flows in the network and increased security against unauthorized entry.

router(router) - a device that transfers data between two networks, including between local and global networks. The router, in fact, is a specialized microcomputer, has its own processor, RAM and permanent memory, operating system.

Gateway: interface device that connects two different types networks. It receives the information, translates it into the required format, and then forwards the translation to its destination.

Shared External Devices include drives connected to the server external memory, printers, plotters and other equipment that becomes available from workstations.
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Organization of data transmission in the network
A necessary condition for the operation of a single local area network is the use network operating system. Such operating systems ensure the sharing of not only network hardware resources (printers, drives, etc.), but also distributed collective technologies when performing a variety of jobs. The most widely used network operating systems Novell NetWare Linux And Windows.
Computers can communicate with each other because there are sets of rules, or protocols which help computers understand each other. Protocols are necessary for the communication process to proceed without errors. Protocols help define how information is sent and how it is received.

Composition of local area networks (LAN) of an enterprise (organization), their topology, protocols, distribution of resources and access rights

The main characteristics of the LAN:

• * territorial extent of the network (length of the common communication channel);
• * maximum data transfer rate;
• * the maximum number of speakers in the network;
• * the maximum possible distance between workstations in the network;
• * network topology;
• * type of physical data transmission medium;
• * maximum number of data transmission channels;
• * type of signal transmission (synchronous or asynchronous);
• * access method of subscribers to the network;
• * structure software networks;
• * the possibility of transmitting speech and video signals;
• * conditions for reliable operation of the network;
• * the possibility of LAN communication with each other and with a network of a higher level;
• * the possibility of using the procedure for establishing priorities when simultaneous connection subscribers to a common channel.

The company has 2 local networks. One in the organization, and the other connects all migration services, access by domain, each user has his own password.

Types of local networks.

All modern local networks are divided into two types:

• · Peer-to-peer
• with centralized control.

In a peer-to-peer network, all computers are equal - each of the computers can be both a server and a client. The user of each of the computers decides for himself what resources will be shared and to whom.

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

Enterprise topology is the stars -- basic topology a computer network in which all computers on the network are connected to a central node (usually a switch) to form a physical network segment. Such a network segment can function both separately and as part of a complex network topology (usually a "tree"). The entire exchange of information takes place exclusively through the central computer, which in this way is assigned a very huge pressure, therefore, it cannot deal with anything other than the network. As a rule, it is the central computer that is the most powerful, and it is on it that all the functions of managing the exchange are assigned. No conflicts in a network with a star topology are in principle impossible, because management is completely centralized.

Organization protocols:

The data transfer protocols IPX/SPX and NETBIOS are used.

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

The SPX protocol assumes that workstations establish communication with each other before starting data exchange. At the SPX protocol level, the delivery of packets transmitted over the network is guaranteed. If necessary, retransmissions of information packets are performed. The SPX protocol is based on IPX and is a higher level protocol.

The NETBIOS protocol is designed to transfer data between workstations. It is an even higher level protocol.

Sometimes in local networks you can find the TCP / IP protocol. This protocol runs on the basis of the UNIX operating system, and is also used to transfer information between computers on a global computer network.

Local computer networks of enterprises have been formed for more than 40 years, since the installation of electronic computers (computers), which sometimes occupied the size of an entire room.

The term "local area networks" came to us from the West. IN English language it sounds like "Local Area Network".
Local Area Network (LAN) is hardware and software used in combination for the task of combining the company's computing resources into a single distributed system for processing and storing information. Thus, installing a LAN means creating a highly functional digital data exchange network.

In addition to computers, other equipment is connected to the LAN: active network equipment, which includes adapters, hubs, switches, and routers, network gateways.

Software can include network operating systems, information transfer protocols and used network technologies. The viability of the future local network depends on the quality of the technologies used.

Widely used technologies in creating local networks at the moment are the following technologies: Asynchronous Transfer Mode (ATM), Gigabit Ethernet and Fast Ethernet (100BaseT). A distinctive feature of modern local networks - high speed data transmission, flexibility, modular architecture.

Virtual Private Network (VPN) technology allows you to combine disparate local area networks into a single corporate network with a high degree of protection and redundant communication channels. VPN networks allow the company to get away from the use of expensive urban communication channels. VPN allows you to use internal communication channels and the Internet for communication of company employees and data transfer.

The enterprise network infrastructure has the following functionality:

File transfer - any, even the smallest local area network has the ability to transfer information.
tools for joint work. LAN users have access to shared folders and files for collaboration.
differentiation of employees' access rights to the Internet
general use of office equipment.
corporate email. Enterprise Server Capabilities Email depending on the settings, they allow you to receive and send capacious attachments, carry out mass mailings, use the general address book employees and others.
information protection is one of the main features of local area networks. network administrator may impose restrictions on employees' access rights to the Internet, organize spam filters for incoming corporate mail traffic, exclude Internet entertainment resources, online sales catalogs, social media to view.

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 newfangled radio, Wi-Fi and other networks, but an inexpensive, but high-quality traditional wired cable network 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 newfangled radio, Wi-Fi and other networks, but an inexpensive, but high-quality traditional wired cable network 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, it is necessary to make one very simple, but very important thing- take a few sheets of paper, a pencil and sit down for a draft business plan. It is very important to more or less clearly "take on a pencil" everything keywords, which will 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”. Okay, we believe that we have in the office with power network Everything is fine. There's only one here important point- 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. It is important to find the 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 get by with wall brackets to secure 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 (recall about 99.9% of the market filled with network filters with tightly-obliquely planted rosettes).

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 waiting times in 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 forwarding by wired network
. Built-in MAC address table (8K MAC address capacity)
. Power LEDs, 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 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 manageable, with potentially 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 network interfaces on user computers, but subscriber outlets 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, you must follow a few simple rules (just 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. The high level of 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 advanced frequency range up to 350 MHz, technologies are applied digital processing pulse signal.

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 30mm

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 troubled lines
* Free phone
* Permanent connection
* Does not require driver installation
* Works with W



INTRODUCTION

Not so long ago, telecommuting was a challenge for employers. But progress, as we all know, does not stand still and modern telecommunication technologies are becoming more and more firmly established in our lives every year. And it's more about working life, in which innovations constantly appear.

Currently, in any organization, in various areas of work, if the enterprise needs computers and there are more than two of them, then it is advisable to combine them into a local area network. The computer network carries huge potentialities: acceleration of the production process; sharing network elements; the ability to quickly access the necessary information; reliable storage and backup of data; information protection; use of modern technology resources (Internet access, electronic document management systems, etc.)

A network is a group of computers connected to each other by communication channels. The channel provides data exchange within the network (i.e. data exchange between computers of this group). The network may consist of two or three computers, or it may unite several thousand PCs.

Physically, data exchange between computers can be carried out via a special cable, telephone line, fiber - optical cable or radio channel.

The purpose of my course project is to organize and describe a local area network (LAN) service center with Internet access.

1 THEORETICAL SECTION

.1 FUNCTIONAL DIAGRAM OF THE LOCAL COMPUTING NETWORK

.1.1 Analysis of the network structure and information needs of the enterprise.

The local area network (LAN) of the service center consists of a ground floor and a basement.

The organization of this network will use:

Network sockets

Switches

Server rack

Software

First floor:

Ground floor:

Mains socket - 13

Hub - 2

Power outlet - 26 Server rack - 1

Hub -3

For created network different information needs are envisaged.

Such as:

· Local computing network

Internet access

Ability to share information between users

· Database

1.2 PLANNING THE NETWORK STRUCTURE

.2.1 Computer network. Topology

Computer network (computer network, data transmission network<#"865298.files/image001.gif">

Figure 1. Types of network topologies

1.2.2 Star topology

Figure 2. Star topology

Star topology - topology view<#"865298.files/image003.gif">

Figure 3. Bus topology

local area network

The topology of the bus type (or, as it is also called, the common bus) by its very structure assumes the identity of the network equipment of computers, as well as the equality of all subscribers in accessing the network. Computers on the bus can only transmit information in turn, since the communication line in this case is the only one. If several computers transmit information at the same time, it will be distorted as a result of overlap (conflict, collision). The bus always implements the mode of the so-called half-duplex (half duplex) exchange (in both directions, but in turn, and not simultaneously).

In the bus topology, there is no explicit central subscriber through which all information is transmitted, this increases its reliability (after all, if the center fails, the entire system controlled by it ceases to function). Adding new subscribers to the bus is quite simple and is usually possible even while the network is running. In most cases, when using a bus, a minimum amount of connecting cable is required compared to other topologies.

Since there is no central subscriber, the resolution of possible conflicts in this case falls on the network equipment of each individual subscriber. In this regard, network equipment with a bus topology is more complicated than with other topologies. However, due to the widespread use of bus topology networks (especially the most popular Ethernet network), the cost of network equipment is not too high.

Having considered three main types of topologies, to build a project in our service center a mixed topology of the type: "Bus - Star" will be involved. This topology provides high reliability, high performance, flexible administration. According to all criteria, it meets the goals and objectives of the service center.

Figure 4. Mixed topology

1.3 WAYS TO MANAGE THE NETWORK

Depending on the scalability of the network, it will depend on how the network will be managed in a given enterprise. There are several ways to manage. Local area networks are divided into two subgroups according to the control method: peer-to-peer and hierarchical (multilevel) networks.

1.3.1 Peer-to-peer 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.

Peer-to-peer networks are also called workgroups. Working group this is a small team, so peer-to-peer networks most often have no more than 30 computers. Peer-to-peer networks are relatively simple.

Since each computer is both a client and a server, there is no need for a powerful central server or other components required for more complex networks.

Peer-to-peer networks are usually cheaper than server-based networks, but require more powerful (and more expensive) computers. In a peer-to-peer network, the performance and security requirements for network software are typically lower than in dedicated server networks.

Figure 5. Peer-to-peer network

1.3.2 Hierarchical networks

Hierarchical networks have one or more servers that store information that is shared between different users. In order to increase the reliability of information storage on the server, two disks working in parallel and duplicating each other can be installed,

at the same time, in case of failure of one of them, the other is automatically included in the work. Depending on how the server is used in hierarchical networks, the following types of servers are distinguished:

File server. In this case, the shared files and/or shared programs are located on the server. One example of using a file server is to host MS Office programs on it. In this case, only a small (client) part of these programs is located on the workstations, requiring insignificant resources. Programs that allow this mode of operation are called network installable programs.

Database server. In this case, the database is hosted on the server (for example, Consultant Plus, Guarantor, Bank customer accounts, etc.). The database on the server can be updated from various workstations and/or provide information upon request from the workstation.

Hierarchical network clients can use operating systems: Windows XP, Windows Vista, Windows 7, servers require special server versions of operating systems.

Figure 6. Hierarchical network

Our service center will use hierarchical network. For our case, this is the most suitable option. So that our network does not turn into an information "garbage dump", and also, in order to increase the reliability of information storage, it is necessary to have several servers. In this case, a file server, an Internet server, and a database server. The server will host MS Office, 1C and other programs, and the workstations will host only a small (client) part of these programs, requiring insignificant resources. It is also necessary for each user to allocate his rights in the local network.

1.4 NETWORKING BASED ON A NETWORK OPERATING SYSTEM

.4.1 Selecting the Operating System

When choosing operating system, you need to know for what purposes it will be used. Here it is necessary to take into account which network is peer-to-peer or hierarchical. Nowadays there are many OS For example:

Windows FamiliesWindows 2000/NT…server 2003/2008….XP/ 7 /8…

Also Linux families

We need our OS to be:

1. Stable

2. Had good protection

Easy to manage

Had good speed

5. Support more than 4GB RAM

Nothing more

Windows Server 2003 is available in four major editions, each targeted at a specific market segment.

All of these editions, with the exception of the Web Edition, are also available in 64-bit editions (AMD64<#"865298.files/image009.gif">

Figure 7. 1 - hey setup step

Figure 8. 2nd stage of setup

Figure 9. 3rd stage of setup

On this computer setup<#"865298.files/image013.gif">

Figure 11. 1st connection option

Figure 12. 2nd connection option

Setup: Consider the first option for setting up the printer.

1. From the Start menu, click Settings > Printers and Faxes

2. On the left side of the Printers and Faxes window, in the Printing Tasks section, to launch a wizard that helps you install the printer, click Add Printer.

In the window with the subheading Local printer or printer connection, select network printer or a printer connected to another computer and click Next >.

4. In the window with the subtitle: Specify a printer, select Connect to a printer or browse printers ("Next" button). In the "Name" field, type the path to the network printer.

For example: \\base\elephant (this is the printer on the 4th floor, HP LaserJet 9000dn)

Figure 13 Add Printer Wizard

5. In the window subtitled Browse Printers, in the Shared Printers field, select Microsoft Windows Network > MI > BASE and select the printer you want to connect there. For example: elephant (this is the printer on the ground floor, HP LaserJet 9000dn). Next >

6. In the window with the subtitle Printer by default, select whether or not to use this printer by default. When printing from an application, if no other printer is selected, printed documents will always be sent to the default printer. Next >.

7. In the window with the subtitle Completing the Add Printer Wizard, click the Finish button.

1.7 SETTING UP THE NOD 32 ANTI-VIRUS SYSTEM

Having an anti-virus program on the server, it must be configured so that the anti-virus database on client machines is updated automatically and via the local network.

Let's start setting up: At the very beginning, we need to set up server updates via the Internet. On the server, open the program window - NOD 32. Go to the section: Settings>Updates, the "Settings" window will open automatic updates”, on the “Location” tab, click the “Servers” button and enter your update server, which is attached to the anti-virus system disk. Then we enter our name and password, which is also attached to the disk. The second step is to set up the "Mirror".

Figure 14. Antivirus settings

A mirror is a folder located on a server that will be accessed by client computers via a local network to update anti-virus programs. To do this: on the mirror tabs, go to the settings. In the window that appears, check the "create an update mirror" box, click on the "Folder" button, create a folder on the C:\ drive, give it a name, for example "NOD obnov", click OK. You need to go to the "Advanced" section and look at which port is used to provide files via HTTP (2221), click OK. On the client machine, open the window antivirus program>Updates > Locations > Servers >Add > ://192.168.98.1 :2221 ie prescribes the IP address of our server and the port of the HTTP server, click OK. Then select our server from the drop-down list and click OK.

1.8 ONLINE RESOURCES

Almost any rapidly developing enterprise has a local area network, and the enterprise also has many peripheral devices, for example: Scanner, printer, plotter, non-standard peripheral device, terminals, depending on the direction of the enterprise. There is such a thing as a shared network resource.

A network share is a device or piece of information to which a connection can be made. remote access from another computer<#"865298.files/image017.gif">

Figure 11. Fiber optic cable

At the heart of each of them is a core of germanium and silicon, covered on top with a silicon shell, cladding and outer coating.

Several layers of buffer skins help to reduce the mechanical impact (friction, stretching, bending, etc.) on the core. The outer shell protects it from temperature changes, humidity, dust and other external adverse factors. The number of optical fibers in the cable can be different. Traditionally produced 4, 6, 8, 12, 16, 24, 32, 48 - fiber cables. Depending on the type of fibers, optical cables are divided into: single-mode and multi-mode.

2.1.4. twisted pair

Twisted pair - type of cable<#"865298.files/image018.gif">

Figure 12. Twisted pair

Unshielded twisted pair: The twisting of conductors is carried out in order to increase the degree of connection between each other, the conductors of one pair and the subsequent reduction of electromagnetic interference<#"865298.files/image019.gif">

Figure 13. Cable - channel

2.2 CABLE LAYING TECHNOLOGY

.2.1 Laying fiber optic cable

The optical cable runs along the lighting poles to the end wall of the building, at the level of the second floor. Then it is attached to the end wall of the building with metal brackets.

Figure 14. Fiber cabling

On the end wall, the fiber optic cable gets into a special corrugated pipe, it is like additional protection, and insulation of the main cable. Then, through a corrugated pipe, the cable enters the room where the SHKOS (Rack Optical Crossover Cabinet) is installed, it is designed for terminating, distributing and switching optical communication cables.

Figure 15. SCOS

From the output ports, through a special fiber-optic patch cord, the fiber itself goes to the media converter. A media converter is a device that converts a signal propagation medium from one type to another. The most common signal propagation medium is copper wires and optical cables. In our case, the media converter converts the light signal coming out of the optical fiber into an electrical signal, which will later be transmitted over copper cables. Twisted Pair Technology

A shielded twisted pair is connected to the output of the media converter, in the Rj - 45 connector. The second end of the twisted pair cable from the first floor goes down to the basement floor through the cable channel. Since the ceiling of the basement floor is hinged, consisting of a metal frame and plasterboard plates. The twisted pair will be laid along the false ceiling, from the inside.

Figure 16. Suspended ceiling

The cable runs along the false ceiling to the office, where the telecommunications cabinet "server cabinet" is located. Where then the cable, twisted pair, is connected to the router, since this cable provides access to the Internet.

2.3 TELECOM CABINET

The telecommunications cabinet, also known as the "server cabinet" - is the cabinet itself, made of aluminum alloy, which makes it lightweight, on which it is securely placed: passive and active network equipment, it provides convenient access to everything network equipment. It is also easy to install and mount in various commercial premises. Cabinets are open and closed this project an open telecommunication cabinet is used.

Figure 17. Server rack

2.3.1 Organization of communication lines in a telecommunication closet

To the first network map the Internet server is connected by a twisted pair cable coming out of the router, it receives Internet traffic. The second network card is connected to the hub using a patch cord, it distributes Internet traffic throughout the network. All available servers are connected to the hub, in our case it is a file server and a database server.

On the back side of the patch panel are the so-called IDC-connectors (connector with insulation displacement), to which the cable, twisted pair are switched. This is the cable that comes from client machines and external switches.

Figure 18. Patch panel. rear side

There are many ports on the front side of the patch panel, the most commonly used number is 12, 24, 25.

Figure 19. Patch panel. Front side

Figure 20. Hub connected by patch cords to a patch panel

We have client machines and external switches connected to the patch panel, from the back. Ports are located on the front side. Each port is connected to a separate machine. Patch cord, connect the patch panel to the hub. Above each port of the patch panel, we sign the number of the cabinet where the client machine connected to this port is located. Also, when laying a twisted pair, we mark the two ends, then to figure out which cable is which. For example, it may be a digital marking, i.e. we hook a tag with the number "1" to one end of the wire and mark the other end with the number "1". In the event of a network break, we are able to easily determine which machine is connected to the corresponding port on the patch panel, as well as which wire. This allows us to reduce the time spent searching for a damaged cable.

Figure 21. Cable marking

Figure 22. Cable installation

From the back side of the patch panel, the twisted pair is led out under the suspended ceiling, because it is there that we will run all the wires, up to the cabinet where the local network is needed. Then, a through hole is drilled in the wall of the office where the network needs to be laid, between the false ceiling and the usual one. A corrugated pipe is inserted into the hole. A cable is pulled through the hole. In the office where the client machines will be located, cable channels are pre-installed, in which the twisted pair and power cable will be located. Then, we lay the cables in the cable channels. We mount the power cable in a power outlet, to ensure this cabinet electricity. We mount the twisted pair cable into special RJ-45 network sockets.

2.3.2 Mounting the twisted pair, to the network socket RJ - 45

1. For installation, we will use: RJ-45 socket<#"865298.files/image029.gif">

Figure 23. Cable crimping

Figure 24 Required tools

2.4 TECHNOLOGY OF CREATING A PATCH - CORD

We take the end of the twisted-pair cable from the bay. We measure the segment of the required length: the cable should freely reach from the computer to the switch, without blocking the passage. It is desirable to calculate the length of the cable so that later it can be put into its box or hidden behind the baseboard.

Carefully remove the top protective layer (outer insulation) of the cut cable. If there is a thread or insulating foil, then cut them off. The insulation is removed at a length of approximately 30-40 mm from the end of the electrical cord. After we removed the top winding of the cable, we see eight strands of wires that differ from each other in color. They are twisted in pairs.

We straighten each wire. All wires must be absolutely even, straight and clearly separated from each other. Next, we make these eight colored wires together (tightly and in one line) in a certain sequence. The sequence is as follows (T568B), from left to right, as shown in the figure:

Figure 25. Crimping a twisted pair

Let's start crimping the ends of the cable. We need crimping pliers. Gently support the end of your wires: Take the connector. It must be turned with the tongue down and the contacts up (figure). While holding the contacts, carefully insert the end of the cable all the way into the connector, so that each wire gets into its own track of the connector. After making sure that the contacts are correctly positioned, we place the connector in the crimping pliers. They have a special connector. Holding the cable, we squeeze the pliers to the stop - all the contacts should “squeeze” well. We take out the ready-made, crimped connector from the pliers. With the second end of the cable, we repeat the same thing as with the first. Now we need to check our patch cord. We take the tester and insert the patch cord into it with both ends. If the indicators on both devices match, then the patch cord is ready for use.

2.5 COMMUNICATION EQUIPMENT OF THE COMPUTER NETWORK

Communication equipment is used to connect computers to a local network. Depending on the scalability of the network, it will depend on what equipment and how much you need to use to organize a LAN.

In my network, to connect computers to a local network, the following communication equipment is used:

Network cards (adapter, network adapter) are expansion cards inserted into expansion ports on system board computer. ABOUT The main function is the transmission and reception of information over the network.

Router (router) - a device used to organize large local networks. Provides traffic between local networks with different network addresses. Routers help reduce network congestion by dividing it into collision domains and broadcast domains, and by filtering packets. They are mainly used to combine networks of different types, often incompatible in architecture and protocols, for example, to combine local Ethernet networks and WAN connections using xDSL, PPP, ATM, Frame relay, etc. protocols. Often a router is used to provide access from a local network to global network Internet, performing the functions of address translation and firewall.

Figure 26 Hub Figure 27 Router

2.6 NETWORK COST CALCULATION

2.6.1 Determination of the cost of the material part of the network

Table 1. The cost of all equipment

Name of equipment	Quantity		Price
Hubs and routers
D-Link 24x10/100Base-TX
D-Link DES-1016A 16port 10/100 Fast Ethernet Switch
D-Link DES-1005D 5port 10/100 Fast Ethernet Switch
Router D - Link DIR-300
Other communication equipment
SHKOS-19-1U-VP-SC-24 Optical box 19" for 24 SC
Media Converter (1UTP, 1SC) D-Link 100Base-TX to 100Base-FX
UPS Server SUA3000I APC Smart-UPS 3000VA
Patch panel 5bites LY-PP5-75 UTP 5e cat., 48 ports
cable system
Cable UTP 2PR 24AWG CAT5e 305m OUTDOOR REXANT
FTP cable 1PR 24AWG CAT5e 305m (A) REXANT
Category 5 RJ-45 Connector
Crimping pliers
Patch cord UTP, Cat.5e, 0.5 m
Patch - cord UTP, Cat.5e, 1 m

CONCLUSION

In this course project, we examined the main issues of creating a local area network in an enterprise. In our case, we organized a local area network in a service center.

There are 39 workstations in our network. Our network has a hierarchical structure, built on a mixed "Bus - Star" topology, which means that the entire network will be controlled through specially designated computers, the so-called servers. To ensure information security, integrity and rapid access to information in our network, we use four servers. Internet server, database server, two file servers, one of them is redundant.

The main device that connects different parts of the network into a single network are hubs. Two types of cables are used, these are twisted pair and fiber optic cable. Cable laying is carried out along cable channels and on a false ceiling.

Based on all of the above, we can conclude that this network is very reliable, but requires constant maintenance. The cost of building the network amounted to 287,457.0 rubles.

LIST OF SOURCES USED

1 Kosarev V.P. "Computers and networks"

2