Create a home network using a router. Do-it-yourself local network: General rules for building a home network and its main components

A network diagram is a table designed to draw up a project plan and monitor its implementation. To build it professionally, there are specialized applications, for example MS Project. But for small enterprises, and especially for personal business needs, there is no point in buying specialized software and spend a lot of time learning the intricacies of working in it. Copes quite successfully with constructing a network diagram table processor Excel, which is installed by most users. Let's find out how to perform the above task in this program.

You can build a network diagram in Excel using a Gantt chart. Having necessary knowledge you can create a table of any complexity, from the guard duty schedule to complex multi-level projects. Let's take a look at the algorithm for performing this task by drawing up a simple network diagram.

Stage 1: building the table structure

First of all, you need to create a table structure. It will represent a wireframe network diagram. Typical elements of a network diagram are columns that indicate serial number specific task, its name, responsible for its implementation and deadlines. But in addition to these basic elements, there may be additional ones in the form of notes, etc.

At this point, the creation of the table template can be considered complete.

Step 2: Create a Timeline

Now we need to create the main part of our network graph - the timeline. It will be a set of columns, each of which corresponds to one period of the project. Most often, one period is equal to one day, but there are cases when the period is calculated in weeks, months, quarters and even years.

In our example, we use the option when one period is equal to one day. Let's make a time scale of 30 days.

1. Let's move on to the right border of our table blank. Starting from this border, we select a range of 30 columns, and the number of rows will be equal to the number of lines in the template that we created earlier.



2. After that, click on the icon "Border" in mode "All Borders".



3. Once the boundaries are outlined, let's add the dates to the time scale. Let's say we will control a project with a validity period from June 1 to June 30, 2017. In this case, the names of the time scale columns must be set in accordance with the specified time period. Of course, entering all the dates manually is quite tedious, so we’ll use the autofill tool called "Progression".

   Insert the date into the first object of the time jackal header "06/01/2017". Moving to the tab "Home" and click on the icon "Fill". Opens additional menu, where you need to select the item "Progression…".



4. The window is being activated "Progression". In a group "Location" value must be marked "Line by line", since we will fill the header, represented as a string. In a group "Type" option must be checked "Dates". In the block "Units" you should place a switch near the position "Day". In the area "Step" must contain a numeric expression "1". In the area "Limit value" indicate the date 30.06.2017 . Click on "OK".



5. The header array will be filled with consecutive dates ranging from June 1 to June 30, 2017. But for the network diagram, we have too wide cells, which negatively affects the compactness of the table, and, therefore, its visibility. Therefore, we will carry out a number of manipulations to optimize the table.
   Select the header of the time scale. Click on the selected fragment. In the list we stop at the item "Cell Format".



6. In the formatting window that opens, move to the section "Alignment". In the area "Orientation" set the value "90 degrees", or move the element with the cursor "Inscription" up. Click on the button "OK".



7. After this, the column names in the form of dates changed their orientation from horizontal to vertical. But due to the fact that the cells did not change their size, the names became unreadable, since they did not fit vertically into the designated elements of the sheet. To change this state of affairs, we again select the contents of the header. Click on the icon "Format" located in the block "Cells". In the list we focus on the option "Auto-fit row height".



8. After the described action, the height of the column names fit into the boundaries of the cells, but the width of the cells did not become more compact. Again select the range of the time scale header and click on the button "Format". This time, select the option from the list "Auto-fit column width".



9. Now the table has become compact, and the grid elements have taken a square shape.

Stage 3: filling in data

Step 4: Conditional Formatting

On next stage work with network diagram We have to fill with color those grid cells that correspond to the period of implementation of a specific event. This can be done using conditional formatting.

1. We mark the entire array of empty cells on the time scale, which is presented as a grid of square elements.



2. Click on the icon « Conditional Formatting» . It is located in the block "Styles" After this, a list will open. You should select the option "Create Rule".



3. A window opens in which you need to create a rule. In the area for selecting the type of rule, mark the item that implies the use of a formula to designate formatted elements. In the field "Format values" we need to set a selection rule, presented as a formula. For our specific case, it will look like this:

   AND(G$1>=$D2;G$1<=($D2+$E2-1))

   But in order for you to be able to convert this formula for your network diagram, which quite possibly will have different coordinates, we need to decipher the written formula.

   "AND" is a built-in Excel function that checks whether all values ​​supplied as its arguments are true. The syntax is:

   AND(logical_value1,logical_value2,...)

   In total, up to 255 boolean values ​​are used as arguments, but we only need two.

   The first argument is written as an expression "G$1>=$D2". It checks that the value in the time scale is greater than or equal to the corresponding value for the start date of a particular activity. Accordingly, the first link in this expression refers to the first cell of the row in the timeline, and the second - to the first element of the event start date column. Dollar sign ( $ ) is set specifically so that the coordinates of the formula that have this symbol, did not change, but remained absolute. And you should place dollar signs in the appropriate places for your case.

   The second argument is represented by the expression "G$1<=($D2+$E2-1)» . It checks that the indicator on the time scale ( G$1) was less than or equal to the project completion date ( $D2+$E2-1). The time scale indicator is calculated as in the previous expression, and the project completion date is calculated by adding the project start date ( $D2) and its duration in days ( $E2). In order to include the first day of the project in the number of days, one is subtracted from this amount. The dollar sign plays the same role as in the previous expression.

   If both arguments of the presented formula are true, then conditional formatting will be applied to the cells in the form of filling them with color.

   To select a specific fill color, click on the button "Format…".



4. In a new window, move to the section "Fill". In a group "Background Colors" Various shading options are presented. We mark the color with which we want the cells of the days corresponding to the period of completion of a specific task to be highlighted. For example, let's choose green. After the shade is reflected in the field "Sample", click on "OK".



5. After returning to the rule creation window, click on the button "OK".



6. After the last action was completed, the grid arrays corresponding to the period of the specific activity were colored green.

At this point, the creation of the network diagram can be considered complete.

As we worked, we created a network diagram. This is not the only version of such a table that can be created in Excel, but the basic principles for performing this task remain unchanged. Therefore, if desired, each user can improve the table presented in the example to suit their specific needs.

Good day!

Eh, if in the 90s of the last century a computer was a luxury, now many people have not one, but several computers/laptops at home. If you connect computers to a local network (even if there are only 2 devices), you can get undeniable advantages:

• the ability to open files located on another PC, work with them, etc. Now you don’t need to run back and forth with a flash drive or disk;
• the ability to make a network printer (scanner, CD/DVD drive, etc.), and use it from all PCs on the local network;
• the ability to play online games (this is a separate and most interesting opportunity that I could talk about for a long time).

In this article, I wanted to look at the issue of building a home local network (and setting it up), which will be useful to all novice users. I’ll take the path of a step-by-step analysis, I’ll start with the question of connecting one PC to another, then I’ll look at setting up Windows, and how, in fact, to share (make available on the local network) folders, printers, etc. So...

When creating a home local network, two options are most often used:

1. connect two computers (PC to laptop, PC to PC, etc.) using a cable (often called twisted pair);
2. buy special "box" called a Wi-Fi router. A PC is connected to the router using a network cable, and laptops, phones, tablets and other devices get access to the Internet via Wi-Fi (the most popular option today).

Option No. 1 - connecting 2 PCs using twisted pair

Pros: simplicity and low cost (you need 2 things: a network card and a network cable); ensuring a sufficiently high speed that not every router is capable of producing, less radio waves in the room.

Cons: extra wires create confusion and get in the way; after reinstalling Windows OS, the network needs to be configured again; In order for Internet access to be on the second PC (2), the first PC (1) must be turned on.

What is needed: each PC must have a network card and a network cable. If you plan to connect more than 2 PCs to a local network (or for one PC to be connected to the Internet and at the same time be on the local network), one of the PCs should have 2-3 or more network cards.

In general, if both PCs have network cards, and you have a network cable (also called an Ethernet cable), then connecting them using it is not difficult. I don't think there's much to consider here.

Note: Please note that usually the green (yellow) LED on network cards starts to light up when you connect a cable to it.

Another important point!

Network cables on sale are different: not only in color and length. The fact is that there are cables for connecting a computer to a computer, and there are those that are used to connect a PC to a router.

For our task needed crossed network cable (or cable crimped cross method- here who calls it what).

In a crossover cable, the yellow and green pairs are swapped at the end connectors; in the standard one (for connecting a PC to a router) - the colors of the contacts are the same.

In general, if two PCs are turned on and working, you connected them with a cable (the LEDs on the network cards blinked), the network icon next to the clock stopped displaying a red cross - this means the PC has found the network and is waiting for it to be configured. This is what we will do in the second section of this article.

Option No. 2 - connecting 2-3 or more PCs using a router

Pros: most devices: phones, tablets, laptops, etc. will have access to the Wi-Fi network; fewer wires under your feet; after reinstalling Windows, the Internet will work.

Cons: purchasing a router (after all, some models are far from cheap); "complex" device setup; radio waves from the router, lower ping and freezing (if the router cannot cope with the load).

What you need: a router (it usually comes with a network cable to connect one PC to it).

As a rule, there are no big problems with connecting the router either: the cable coming from the Internet provider is connected to a special one. router connector (it is often called “Internet”), and local PCs are connected to other connectors (“Lan ports”). Those. the router becomes an intermediary (an approximate diagram is shown in the screenshot below. By the way, in this diagram there may not be a modem on the right, it all depends on your Internet connection) .

By the way, pay attention to the LEDs on the router case: when you connect an Internet cable from the provider, from the local PC, they should light up and blink. In general, setting up a Wi-Fi router is a separate big topic, and for each router, the instructions will be slightly different. Therefore, it is hardly possible to give universal recommendations in one separate article...

By the way, when connecting via a router, the local network is usually configured automatically (i.e., all computers connected via a network cable should already be on the local network, there will be a couple of small touches left (more on them below)). The main task after this is to set up a Wi-Fi connection and access to the Internet. But because This article is about the local network, I’m not focusing on that...

Setting up a local network (Windows 7, 8, 10)

In this subsection of the article, I will give universal instructions, regardless of how your local network is organized: connected via a network cable, or using a router. Where the settings relate to a specific option, there will be notes.

Note: all settings are relevant for Windows 7, 8, 8.1, 10.

Computer and workgroup name

Allegory: each person has his own name, surname, patronymic, date of birth, city, etc. - no two people are exactly alike. It’s the same on the network - there shouldn’t be computers with the same name...

The first thing you need to do when setting up a local network is to check and configure workgroup name And computer name. Moreover, this needs to be done on every computer on the local network!

To find your computer name, open the Windows Control Panel at: Control Panel\System and Security\System (screen below). Next, make sure the following:

1. PC name and slave the group must be in Latin;
2. Each PC/laptop on the local network should have its own unique name(for example: PC1, PC2, PC3);
3. Every PC/laptop should have same working group (for example: WORKGROUP).

To change the name and workgroup, click the "Change settings" button.

Changing workgroup and PC name

In general, when you bring all the names in accordance with the requirements above, you can proceed to the next stage of setup.

Enable printer and folder sharing

Relevant both for connecting via a router and directly...

This innovation appeared in Windows 7 and supposedly provides greater security for the OS (in my opinion, it only creates the need for additional configuration of the local network). The bottom line is that, by default, Windows blocks and does not allow access to open and share folders, printers, etc., until the security policy is “softened.”

To remove this lock and enable sharing, you need to:

Setting up IP addresses, DNS, masks, gateways

For a network organized using a router

In general, for PCs connected to a local network using a router, you usually don’t need to configure anything (everything works by default). If something is wrong, just in case, I recommend going in and checking the connection properties.

To do this, you first need to open "network connections" . This is done simply:

1. first open the window "Run"- combination of buttons Win+R;
2. then enter the command ncpa.cpl and press Enter(works in all versions of Windows 7, 8, 10).

How to open network connections // ncpa.cpl

Local Area Connection Properties

To connect PC to PC via network cable

PC 1

By PC 1 I mean a computer that has two network cards: one of them is connected to the provider’s Internet cable, and the second is connected to a local network cable going to PC 2.

Note: although, an Internet cable from a provider does not have to be present. If it is not there, select PC 1 and PC 2 - randomly...

And so, we open LAN network connection properties(how this is done - see just above in the article).

1. IP address: 192.168.0.1;
2. subnet mask: 255.255.255.0 (see screenshot below);
3. save the settings.

IN properties of IP version 4 (TCP/IPv4) second PC, you need to set the following parameters:

1. IP address: 192.168.0.2,
2. subnet mask: 255.255.255.0;
3. default gateway: 192.168.0.1;
4. preferred DNS server: 192.168.0.1 (see screenshot below);
5. save the settings.

Actually, the local network setup itself is complete. Now you can start the fun part - sharing and using shared local network resources. Actually, that's what we were going for...

Sharing Internet access on a second PC

Relevant for PCs connected directly with a LAN cable...

We need to configure PC 1 (i.e. the one to which we have the provider’s Internet cable connected).

First we open network connections : press combination Win+R, enter ncpa.cpl, further Enter .

How to open network connections //ncpa.cpl

Next, open the tab "Access", and check the box next to the item "Allow other network users to use this computer's Internet connection" . Save your settings.

Allow other users to access the Internet

If everything was done correctly, the Internet will be on both computers.

Note: naturally, for the Internet to be on PC 2, PC 1 must be turned on! This, by the way, is one of the inconveniences of such a local network; when connected via a router, the Internet will be available no matter which PC is turned on/off.

Sharing folders/files for public access

3) Set the resolution: read or read and write.

Note:

• read enabled: users will only be able to copy your files to themselves (they will not be able to delete or change them!);
• read and write enabled: Local network users will have full control over files in folders: they can delete all files, change any of them, etc. In general, I would not recommend providing such access to important and large folders (to transfer files, it is better to create a separate folder to which you give full access).

5) After a few seconds, Windows will report that the folder has been opened for public access. So everything went well.

6) To access the folder:

1. open the explorer;
2. then open the “Network” tab (on the left, at the bottom of the window);
3. open computer name, on which the folder was shared. As you can see in the screenshot below, it is shared, you can go into it and start copying (reading) any files.

Sharing a printer (shared network printer)

1) The first thing you need to do is open the control panel: control panel/hardware and sound/devices and printers.

3) Then open the tab "Access" and check the box "Share this printer" . Save the settings (see screenshot below). Actually, the printer is now shared and can be used by other PCs/laptops/tablets and other devices on the local network.

How to share a printer

4) To connect a network printer, open conductor, select computer name , on which the printer is shared. Next you should see it: click on it right mouse button and select the option from the menu connections .

How to connect a network printer

5) Then you can open any document, press Ctrl+P (File/Print), and try to print a page.

Note: By default, Windows usually specifies a different printer (not the one you connected over the network). Don't forget to change it when printing.

Regarding the local network printer, I recommend reading my detailed article on this topic. It describes some points in more detail. Link below.

"Creating" a network printer -

This is where I end this article. Happy and quick setup everyone.

If you use not only one computer at home, but also other similar devices, then they can be combined into a home network. In this case, you can create a home network through a router, which will have access to the Internet.

A local network through a router will allow you to easily connect all your devices. You will then be able to exchange files over the local network, play games or use it for other purposes.

To do this, you will only need to purchase a special device – a router. Using a router, communication is carried out between devices connected to the network, and a home network is created via a wifi router. If your devices use one router to access the Internet, it means that there is a network between these devices. It does not matter how your devices are connected, using a network cable or wireless Wi-Fi.

To create a local network through a router, you need to connect the necessary devices directly to the router, or use a wireless connection. All modern routers can use a wired or wireless connection option. But you can also use a router to connect several networks with each other.

Creating a home network through a router is usually done using the star principle. When connecting using this scheme, all devices that you plan to use must be connected to the router independently of each other. The router in this case is the center of the resulting star, or more precisely the network. In this case, the router itself connects to the provider’s network and can distribute the Internet to devices connected to it. This connection can be seen schematically in the figure below.

Star connection to router

Router for home network

The router is the main device for creating a network. Before you create a network through a router, you must select a suitable router model. You need to know exactly the type of connection used by your provider (cable connection or telephone connection). If a cable connection is used, then the router must be selected with a WAN connector, and if a telephone line is used, then there must be an ADSL connector.

In addition, other options are possible when using a 3G/4G modem, telephone (“STREAM”) or cable modem (“AKADO”). When using the last two options, a special modem is also required. Such a modem can be a separate device or built into the router itself. You can see the diagram for connecting devices and creating a network through a router in the figure below.

On the back or side of the router are the device ports used for connection. The port that is used to connect to the Internet is called a WAN port. Ports for wired connection of a computer, network storage device or other devices to a local network are called LAN ports. There are several such ports, but mostly there are four. If the number of ports does not suit you and you need to connect more devices, you can use a network switch. When installing such a switch with eight ports, you connect one port to the router, and the remaining seven can be used to connect your devices. Switches come in 100-megabit and gigabit versions. Using a gigabit switch makes sense if you need a fast connection between your computer and a network drive. This will not affect the Internet speed itself. Setting up a network through a router can be done through the settings in the router’s web interface.

In addition to wired connection of devices using Ethernet technology, other options are possible. The network can be created via electrical wiring (HomePlug). But most often a wifi network is created through a router using a wireless connection. These methods have different maximum speeds and these characteristics can be seen in the table below.

When choosing a router for a home network with WIFI, a router using 802.11n gives the best results, as it provides better performance and signal coverage compared to 802.11g technology. In addition, you should pay attention to other useful functions, such as the built-in FTP client or USB port, which can be used to connect a flash drive, printer or network drive.

How to make a network through a router

Opening a port on the TP-LINK TL-WR841N router

As an example, we will describe setting up a home network through a router using the TP-Link TL-WR841N router model, which connects to the Internet. In this case, one of the computers will be connected to the router using a network cable, and the second computer via a wireless connection. A local network can also be configured for more computers. On each computer, you need to share the necessary resources so that you can access them from every device on the network.

First, you need to check that the Internet is supplied to the router. When a cable from the provider is connected to the WAN port on the router, the corresponding indicator on the front panel should blink. If the indicator does not light, then you need to update the router firmware. To do this, download the latest firmware from the manufacturer's website. Or there may be a bad cable connection and you need to re-crimp the cable connector. If everything works fine, then you can start creating a local network through the router.

Checking the physical connection

It is necessary to check the connection between computers before setting up a network through a router. You need to ping between them. To do this check, you need to go to the router menu from your computer and find the value of the IP address of another computer in the settings.

To do this, type the network address of the router in your browser, usually 192.168.1.1 and go to the router settings. In the settings, open the tab called “DHCP”, and then “DHCP Clients List”. In this window you will see devices connected to your router. Remember the address assigned to the second computer in order to ping it. Then you need to click the computer Start menu and enter cmd in the search bar to find a utility with this name and run it.

In the window that appears, you need to enter the ping command and write the address of the second computer. After that, press enter and see the result of the command. If the exchange of packets takes place, then the connection between the computers is established and you can already set up a home network through the router.

If there is no packet transmission, then the router does not see the network. Perhaps the reason is in the settings of the antivirus program. Then you need to disable the firewall and antivirus. You can go to the antivirus network settings and find the option to change the network security mode for the computer. There you need to check the option to allow sharing.

Setting up a local network via a router

First you need to check which workgroup each computer is connected to and give them a name accordingly. You need to make sure that the name is written in Latin characters and, if necessary, change it. To do this, you need to right-click on the My Computer icon and select Properties. Then select the Advanced settings option and open the Computer name item there. Here you can change the computer name and group name. After all the settings, you need to click Ok and restart the computer. Now you can set up a local network through the router.

All these steps must be performed on all connected computers that will use the local network via a wifi router. After this, you need to open the computer start menu and open Control Panel. Here we are interested in the Network Control Center. It is important that Home network is selected in the network settings. If everything is so, then you can click the Ready to create button.

Now you need to click the appropriate button to create a homegroup.

Now you need to specify which elements you want to have shared access to.

After this, a window with a password will open, you need to write it down and click Finish. In the next window you need to click the button to change additional parameters.

In the advanced sharing settings, you need to disable the option to require a password on the local network. Then the General tab also opens and this password protected item is disabled. Now don’t forget to click – Save changes.

Now the basic local network settings are done, and you need to reboot all configured computers. Check whether all configured computers can see each other on the created network. To do this, you just need to go to My Computer and click on Network. All computers connected to the network should be displayed, both via a wired connection and wirelessly, using a wifi network through a router for communication.

Now you can use the network via a wi fi router. But, if you log into another computer over the network, you will only get access to the Shared Folder. To gain access to a particular disk or individual files, you need to make the appropriate settings.

Setting up sharing

To configure shared access to a folder or drive, you need to open the folder or drive, respectively, click on Sharing, and then select the advanced settings item.

In the window that appears, you need to select the option to open public access by checking the box and clicking Ok. If necessary, you can also specify a name for the share.

After this configuration, all devices connected to your network will have shared access to the specified resource. When you set up your local network, it is recommended that you save a backup copy of the network configuration on your computer. This will save you from repeating the actions taken.

Two routers on the same network

Sometimes it becomes necessary to connect two routers to a network. This can be done by connecting several routers together.

Before you create a router-router network, you need to imagine the end result of such work. Routers can be connected to combine two local networks, can be used as a common access point to the Internet, or to connect various devices to a second router via a wired or wireless connection.

You can connect two routers using a network cable or a wireless Wi-Fi connection and set up a Wi-Fi network through the router. When choosing a wired connection for routers, when one of them is connected to the Internet, you need to follow these steps.

First you need to connect one end of the network cable to the LAN port of the router that is accepted as the main one. You must connect the other end of the cable to the WAN port of the second router.

Setting up a home network router begins with setting up the main router. You must enable the DHCP function in the settings. After this, you need to open the “IP address” menu for the second router and check the box to automatically obtain an IP address.

If you need to connect two routers via a wireless connection, then in the settings of the second router you need to enable the option to search for wireless networks. You can now connect to the Wi-Fi network created by the first router. To complete the setup, you also need to enable the DHCP function in the router settings, and then configure automatic acquisition of an IP address. Now you know how to connect your router to a WiFi network created by another router.

Network printer via router

You can set up network access to the printer. Here we will describe a method that is suitable for a printer that does not have a special built-in Wi-Fi module. To connect, you only need a router that has a built-in USB port for a printer. For the above connection, a router model ASUS WL-520GU and Xerox Workcenter PE114e will be used.

The printer can only be connected via a USB port, so a standard connection to a computer using sharing imposes some restrictions. To be able to always access the printer, the main computer to which the printer is connected must always be turned on. This is not always convenient and in such a situation it is better to use a printer connection to the router.

To properly configure the printer connection to your router, you need to open the computer Start menu and select Devices and Printers. In this window you need to open the Printer Installation item. When a new window opens, you need to select the type of printer to be added (local) and click Next to continue setting up.

Now you need to configure the printer port. You need to select the option -Create a new port, and select the port type - Standard TCP, as in the figure below, and then click Next to continue the configuration.

In the next window you need to enter the network IP address of the printer. Here you need to enter the router address, which in our case will be 192.168.1.1. You can enter any name for the port name, but you can leave the default one after entering the printer’s IP address (the network address of the router). The option to poll the printer and select a driver can be left enabled (checkbox below). This option will not affect the speed of the process.

After this, the computer will need some time until it finds the TCP/IP Port that you specified. This will be indicated by the corresponding window.

If the port is not found, a window will appear asking you to enter additional information about the port. In this case, you must select Device Type – Special, check the appropriate box, and click Next.

If everything went well, a window with port settings will open. Make sure that all settings are set as in the figure below.

In the next printer driver installation window, you need to select the name of your printer and its model. It is possible that you will not find the name of your printer in the list provided. Then you just need to click a button to install the printer driver from the disk. In this case, you must indicate the exact path to the driver file in the appropriate field. You can download the latest version of the driver on the Internet from the printer manufacturer’s website.

If you have already installed drivers for such a printer, a corresponding window will appear asking which driver version to use. It is recommended to leave the default selection and use the installed driver.

After this, you can set any suitable name for the printer, which will then be visible in the Devices and Printers menu. You can leave the default name for the printer, and then click Next.

Network printer name

In the next window, you can set up printer sharing. But since the printer will already be connected to your router, you don’t have to use the printer sharing option. It is recommended to leave the default value, do not use public access.

You can allow the printer to be used over a network

On the last page of the printer settings, you can leave or remove the option to use a custom printer as the default. After this, you can test the printer and print a test page. To complete the printer setup, click Finish.

Access to the printer is now configured on your computer. To access the printer from other computers, you need to repeat these same settings for each of your computers.

Let's imagine the situation of developing a capital construction project at a manufacturing enterprise. The project has been successfully initiated and planning work is in full swing. Formed and approved, the milestone plan has been adopted. A primary version of the calendar plan has been developed. Since the task turned out to be quite large-scale, the curator decided to develop a network model as well. The calculation of a network diagram in the applied aspect of its execution is the subject of this article.

Before starting the simulation

The methodological basis of network project planning is presented on our website in several articles. I will just refer to two of them. These are materials devoted in general and directly. If during the course of the story you have questions, review the previously presented understandings; the main essence of the methodology is outlined in them. In this article we will look at a small example of a local part of a complex of construction and installation works as part of a significant project implementation. We will perform calculations and modeling using the “vertex-work” method and the classic tabular method (“vertex-event”) using the MKR (critical path method).

We will begin constructing the network diagram based on the first iteration of the calendar plan, made in the form of a Gantt chart. For clarity purposes, I propose not to take precedence relations into account and to simplify the sequence of actions as much as possible. Although this rarely happens in practice, let’s imagine in our example that the operations are arranged in a “finish-start” sequence. Below you will find two tables: an extract from the list of project works (a fragment of 15 operations) and a list of network model parameters necessary for presenting formulas.

An example of a fragment of a list of operations of an investment project

List of network model parameters to be calculated

Don't be intimidated by the abundance of elements. Building a network model and calculating parameters is quite simple. It is important to prepare thoroughly, to have at hand a hierarchical structure of work, a linear Gantt chart - in general, everything that makes it possible to determine the sequence and interrelations of actions. Even the first time you run a graph, I recommend having formulas for calculating the required values ​​in front of you. They are presented below.

Formulas for calculating network diagram parameters

What do we need to determine when constructing the graph?

1. An early start to ongoing work that includes multiple connections from previous operations. We select the maximum value from all early endings of previous operations.
2. Late ending of the current activity from which multiple links exit. We select the minimum value from all late starts of subsequent actions.
3. The sequence of activities that form the critical path. For these actions, early and late starts are equal, as are early and late finishes, respectively. The reserve for such an operation is 0.
4. Full and private reserves.
5. Work intensity coefficients. We will consider the logic of the formulas for reserves and the work intensity coefficient in a special section.

Sequence of modeling actions

Step one

We begin constructing a network diagram by placing task rectangles sequentially from left to right, applying the rules described in previous articles. When performing modeling using the “vertex-work” method, the main element of the diagram is a seven-segment rectangle, which reflects the parameters of the beginning, end, duration, time reserve and name or number of operations. A diagram of its parameters is shown below.

Diagram of the work image on the network diagram

The result of the first stage of constructing a network diagram

In accordance with the logic of the sequence of operations, using a specialized program, MS Visio or any editor, we place images of work in the format specified above. First of all, fill in the names of the actions to be performed, their numbers and duration. We calculate the early start and early end taking into account the formula for the early start of the current action in the conditions of several incoming connections. And so we go until the final fragment of the operation. At the same time, in our example project, the same Gantt chart does not provide for outgoing connections from operations 11, 12, 13 and 14. It is unacceptable to “hang” them on the network model, so we add fictitious connections to the final work of the fragment, highlighted in blue in the figure.

Step two

Finding the critical path. As you know, this is the path that has the longest duration of the actions that are included in it. Looking through the model, we select connections between activities that have maximum early termination values ​​for activities. The designated critical path is highlighted with red arrows. The result obtained is presented in the intermediate diagram below.

Network diagram with a highlighted critical path

Step three

Fill in the values ​​for late finish, late start and full work reserve. To perform the calculation, we go to the final work and take it as the last operation of the critical path. This means that the later end and start values ​​are identical to the earlier ones, and from the last operation of the fragment we begin to move backwards, filling in the bottom line of the action diagram. The calculation model is shown in the diagram below.

Scheme for calculating late starts and finishes outside the critical path

The final view of the network diagram

Step four

The fourth step of the network modeling and calculation algorithm is the calculation of reserves and tension coefficient. First of all, it makes sense to pay attention to the total reserves of paths of non-critical directions (R). They are determined by subtracting from the duration of the critical path the time duration of each of these paths, numbered on the final network diagram.

• R path number 1 = 120 – 101 = 19;
• R path number 2 = 120 – 84 = 36;
• R of path number 3 = 120 – 104 = 16;
• R path number 4 = 120 – 115 = 5;
• R path number 5 = 120 – 118 = 2;
• R path number 6 = 120 – 115 = 5.

Additional model calculations

The calculation of the total float of the current operation is carried out by subtracting the early start from the late start value or the early finish from the late finish value (see the calculation diagram above). The general (full) reserve shows us the possibility of starting the current work later or increasing the duration by the duration of the reserve. But you need to understand that you should use the full reserve with great caution, because the work that is farthest from the current event may end up without a reserve of time.

In addition to full reserves, network modeling also operates with private or free reserves, which represent the difference between the early start of subsequent work and the early completion of the current one. The private reserve shows whether it is possible to move the earlier start of the operation forward without affecting the start of the next procedure and the entire schedule. It should be remembered that the sum of all partial reserve values ​​is identical to the total reserve value for the path in question.

The main task of performing calculations of various parameters is to optimize the network schedule and assess the probability of completing the project on time. One of these parameters is the tension coefficient, which shows us the level of difficulty in completing the work on time. The coefficient formula is presented above as part of all calculation expressions used to analyze the network diagram.

The tension coefficient is defined as the difference between one and the quotient of the total reserve operating time divided by the difference in the duration of the critical path and the special design value. This value includes a number of segments of the critical path that coincide with the maximum possible path to which the current operation (i-j) can be assigned. Below is the calculation of private reserves and work intensity factors for our example.

Table for calculating private reserves and tension coefficient

The tension coefficient varies from 0 to 1.0. A value of 1.0 is set for activities on the critical path. The closer the value of a non-critical operation is to 1.0, the more difficult it is to stay on schedule for its implementation. After the coefficient values ​​for all chart actions are calculated, operations, depending on the level of this parameter, can be categorized as:

• critical zone (Kn more than 0.8);
• subcretic zone (Kn more than or equal to 0.6, but less than or equal to 0.8);
• reserve zone (Kn less than 0.6).

Optimization of the network model, aimed at reducing the overall duration of the project, is usually achieved by the following activities.

1. Redistribution of resources in favor of the most stressful procedures.
2. Reducing the labor intensity of operations located on the critical path.
3. Parallelization of critical path activities.
4. Redesign of the network structure and composition of operations.

Using the table method

Well-known scheduling software (MS Project, Primavera Suretrack, OpenPlan, etc.) are capable of calculating key parameters of the project network model. In this section, we will use the tabular method to configure such a calculation using conventional MS Excel tools. To do this, let’s take our example of a fragment of project operations of a project in the field of construction and installation work. Let's arrange the main parameters of the network diagram in the columns of the spreadsheet.

Model for calculating network diagram parameters in a tabular way

The advantage of performing calculations in a tabular manner is the ability to easily automate calculations and avoid a lot of errors associated with the human factor. We will highlight in red the numbers of operations located on the critical path, and in blue we will mark the calculated positions of private reserves exceeding the zero value. Let us analyze step by step the calculation of network diagram parameters for the main positions.

1. Early starts of operations following current work. We configure the calculation algorithm to select the maximum value from the early end time of several alternative previous actions. Take, for example, operation number 13. It is preceded by operations 6, 7, 8. Of the three early finishes (71, 76, 74, respectively), we need to select the maximum value - 76 and set it as the early start of operation 13.
2. Critical path. Carrying out the calculation procedure according to point 1 of the algorithm, we reach the end of the fragment, finding the value of the duration of the critical path, which in our example was 120 days. The highest early completion values ​​among the alternative actions indicate operations on the critical path. We mark these operations in red.
3. Late completions of activities preceding the current job. Starting from the end work, we begin to move in the opposite direction from actions with higher numbers to operations with lower ones. In this case, from several alternatives for outgoing work, we choose the least knowledge of the late start. Late starts are calculated as the difference between the selected values ​​of late finishes and operation durations.
4. Operation reserves. We calculate total (total) reserves as the difference between late starts and early starts or between late finishes and early finishes. The values ​​of private (free) reserves are obtained by subtracting the early start of the next operation from the early end of the current one.

We examined practical mechanisms for drawing up a network schedule and calculating the main parameters of the project's time duration. Thus, we have come close to exploring the possibilities of analysis carried out with the aim of optimizing the network model and directly forming an action plan to improve its quality. This topic takes up little space in the project manager’s body of knowledge and is not that difficult to understand. In any case, every PM must be able to reproduce the visualization of the graph and perform the accompanying calculations at a good professional level.

Why are local networks needed, and what are they? How to connect several computer devices to one Internet channel at once? What equipment is required to build a home network? You will receive answers to all these and other equally important questions in this material.

Introduction

Before you learn how to design and configure home local networks yourself, let’s immediately answer the most important question: “Why are they needed?”

The concept of a local network itself means the unification of several computers or computer devices into a single system for the exchange of information between them, as well as the sharing of their computing resources and peripheral equipment. Thus, local networks allow:

Exchange data (movies, music, programs, games, etc.) between network members. At the same time, to watch movies or listen to music, it is absolutely not necessary to record them on your hard drive. The speeds of modern networks allow this to be done directly from a remote computer or multimedia device.

Connect several devices simultaneously to the global Internet through one access channel. This is probably one of the most popular functions of local networks, because these days the list of equipment that can use a connection to the World Wide Web is very large. In addition to all kinds of computer equipment and mobile devices, TVs, DVD/Blu-Ray players, multimedia players and even all kinds of household appliances, from refrigerators to coffee makers, have now become full participants in the network.

Share computer peripherals , such as printers, MFPs, scanners and network attached storage (NAS).

Share the computing power of computers of network participants. When working with programs that require complex calculations, such as 3D visualization, to increase productivity and speed up data processing, you can use the free resources of other computers on the network. Thus, having several weak machines connected to a local network, you can use their combined performance to perform resource-intensive tasks.

As you can see, creating a local network even within one apartment can bring a lot of benefits. Moreover, having several devices at home that require an Internet connection has long been not uncommon, and combining them into a common network is an urgent task for most users.

Basic principles of building a local network

Most often, local networks use two main types of data transfer between computers - by wire, such networks are called cable and use Ethernet technology, and also using a radio signal over wireless networks built on the basis of the IEEE 802.11 standard, which is better known to users as Wi -Fi.

Today, wired networks still provide the highest bandwidth, allowing users to exchange information at speeds of up to 100 Mbps (12 Mbps) or up to 1 Gbps (128 Mbps) depending on the equipment used (Fast Ethernet or Gigabit Ethernet). And although modern wireless technologies, purely theoretically, can also provide data transfer up to 1.3 Gbit/s (Wi-Fi 802.11ac standard), in practice this figure looks much more modest and in most cases does not exceed 150 - 300 Mbit/s. The reason for this is the high cost of high-speed Wi-Fi equipment and the low level of its use in current mobile devices.

As a rule, all modern home networks are arranged according to the same principle: user computers (workstations) equipped with network adapters are connected to each other through special switching devices, which can be: routers (routers), switches (hubs or switches), points access or modems. We will talk in more detail about their differences and purposes below, but for now just know that without these electronic boxes, it will not be possible to combine several computers into one system at once. The maximum that can be achieved is to create a mini-network of two PCs by connecting them to each other.

At the very beginning, you need to determine the basic requirements for your future network and its scale. After all, the choice of the necessary equipment will directly depend on the number of devices, their physical placement and possible connection methods. Most often, a home local network is combined and can include several types of switching devices. For example, desktop computers can be connected to the network using wires, and various mobile devices (laptops, tablets, smartphones) can be connected via Wi-Fi.

For example, consider the diagram of one of the possible options for a home local network. It will involve electronic devices designed for various purposes and tasks, as well as using different types of connections.

As can be seen from the figure, several desktop computers, laptops, smartphones, set-top boxes (IPTV), tablets and media players and other devices can be combined into a single network. Now let's figure out what equipment you will need to build your own network.

Network card

A network card is a device that allows computers to communicate with each other and exchange data on a network. All network adapters can be divided into two large groups by type - wired and wireless. Wired network cards allow you to connect electronic devices to a network using Ethernet technology using a cable, while wireless network adapters use Wi-Fi radio technology.

As a rule, all modern desktop computers are already equipped with Ethernet network cards built into the motherboard, and all mobile devices (smartphones, tablets) are equipped with Wi-Fi network adapters. At the same time, laptops and ultrabooks are mostly equipped with both network interfaces at once.

Despite the fact that in the vast majority of cases, computer devices have built-in network interfaces, sometimes it becomes necessary to purchase additional cards, for example, to equip the system unit with a Wi-Fi wireless communication module.

Based on their design implementation, individual network cards are divided into two groups - internal and external. Internal cards are designed for installation in desktop computers using interfaces and their corresponding PCI and PCIe connectors. External cards are connected via USB connectors or legacy PCMCIA (laptops only).

Router (Router)

The main and most important component of a home local network is a router or router - a special box that allows you to combine several electronic devices into a single network and connect them to the Internet through one single channel provided to you by your provider.

A router is a multifunctional device or even a minicomputer with its own built-in operating system, which has at least two network interfaces. The first one is LAN (Local Area Network ) or LAN (Local Area Network) is used to create an internal (home) network, which consists of your computer devices. The second - WAN (Wide Area Network) or WAN (Wide Area Network) is used to connect a local network (LAN) to other networks and the World Wide Web - the Internet.

The main purpose of devices of this type is to determine the routes (routing) of data packets that the user sends to or requests from other, larger networks. It is with the help of routers that huge networks are divided into many logical segments (subnets), one of which is the home local network. Thus, at home, the main function of a router can be called organizing the transfer of information from a local network to a global one, and back.

Another important job of a router is to limit access to your home network from the World Wide Web. Surely you are unlikely to be happy if anyone can connect to your computers and take or delete from them whatever they want. To prevent this from happening, the data flow intended for devices belonging to a specific subnet must not go beyond its boundaries. Therefore, from the general internal traffic generated by local network participants, the router selects and sends to the global network only that information that is intended for other external subnets. This ensures the security of internal data and saves overall network bandwidth.

The main mechanism that allows the router to limit or prevent access from the public network (outside) to devices on your local network is called NAT (Network Address Translation). It also provides all users of your home network with access to the Internet by converting multiple internal device addresses into one public external address that is provided to you by your Internet service provider. All this makes it possible for computers on a home network to easily exchange information with each other and receive it from other networks. At the same time, the data stored in them remains inaccessible to external users, although access to it can be provided at any time at your request.

In general, routers can be divided into two large groups - wired and wireless. Already from the names it is clear that all devices are connected to the first ones only using cables, and to the second ones, both with the help of wires and without them using Wi-Fi technology. Therefore, at home, wireless routers are most often used to provide Internet access and network computer equipment using various communication technologies.

To connect computer devices using cables, the router has special sockets called ports. In most cases, the router has four LAN ports for connecting your devices and one WAN port for connecting your ISP cable.

In order not to overload the article with redundant information, we will not consider in detail the main technical characteristics of routers in this chapter; I will talk about them in a separate article, on choosing a router.

In many cases, a router may be the only component needed to build your own local network, since there is simply no need for the rest. As we have already said, even the simplest router allows you to connect up to four computer devices using wires. Well, the number of equipment that receives simultaneous access to the network using Wi-Fi technology can be in the tens, or even hundreds.

If, at some point, the number of LAN ports on the router is no longer enough, then to expand the cable network, you can connect one or more switches to the router (discussed below), which act as splitters.

Modem

In modern computer networks, a modem is a device that provides Internet access or access to other networks through regular wired telephone lines (xDSL class) or using wireless mobile technologies (3G class).

Conventionally, modems can be divided into two groups. The first includes those that connect to a computer via a USB interface and provide network access to only one specific PC, to which the modem is directly connected. In the second group, the already familiar LAN and/or Wi-Fi interfaces are used to connect to a computer. Their presence indicates that the modem has a built-in router. Such devices are often called combined, and they should be used to build a local network.

When choosing DSL equipment, users may encounter certain difficulties caused by confusion in its names. The fact is that often in the assortment of computer stores, two very similar classes of devices are located side by side: modems with built-in routers and routers with built-in modems. What is the difference between them?

These two groups of devices practically do not have any key differences. Manufacturers themselves position a router with a built-in modem as a more advanced option, equipped with a large number of additional functions and improved performance. But if you are only interested in basic capabilities, for example, such as connecting all computers on your home network to the Internet, then there is not much difference between modem-routers and routers where a DSL modem is used as an external network interface.

So, to summarize, a modern modem with which you can build a local network is, in fact, a router with an xDSL or 3G modem as an external network interface.

A switch or switch is used to connect various nodes of a computer network and exchange data between them via cables. The role of these nodes can be either individual devices, for example a desktop PC, or entire groups of devices united into an independent network segment. Unlike a router, a switch has only one network interface - LAN and is used at home as an auxiliary device primarily for scaling local networks.

To connect computers using wires, like routers, switches also have special socket ports. In models aimed at home use, their number is usually five or eight. If at some point the number of ports on the switch is no longer enough to connect all devices, you can connect another switch to it. Thus, you can expand your home network as much as you like.

Switches are divided into two groups: managed and unmanaged. The first, as the name suggests, can be controlled from the network using special software. Although they have advanced functionality, they are expensive and not used at home. Unmanaged switches distribute traffic and regulate the speed of data exchange between all network clients automatically. These devices are ideal solutions for building small and medium-sized local networks, where the number of participants in the exchange of information is small.

Depending on the model, switches can provide a maximum data transfer speed of either 100 Mbit/s (Fast Ethernet) or 1000 Mbit/s (Gigabit Ethernet). Gigabit switches are best used for building home networks where you plan to frequently transfer large files between local devices.

Wireless access point

To provide wireless access to the Internet or local network resources, in addition to a wireless router, you can use another device called a wireless access point. Unlike a router, this station does not have an external WAN network interface and is equipped in most cases with only one LAN port for connecting to a router or switch. Thus, you will need an access point if your local network uses a regular router or modem without Wi-Fi support.

The use of additional access points in a network with a wireless router may be justified in cases where a large Wi-Fi coverage area is required. For example, the signal strength of a wireless router alone may not be enough to completely cover the entire area in a large office or multi-story country house.

Access points can also be used to organize wireless bridges, allowing you to connect individual devices, network segments or entire networks with each other using a radio signal in places where laying cables is undesirable or difficult.

Network cable, connectors, sockets

Despite the rapid development of wireless technologies, many local networks are still built using wires. Such systems have high reliability, excellent throughput and minimize the possibility of unauthorized connection to your network from the outside.

To create a wired local network in home and office environments, Ethernet technology is used, where the signal is transmitted over the so-called “twisted pair” (TP-Twisted Pair) - a cable consisting of four copper pairs of wires twisted together (to reduce interference).

When building computer networks, predominantly unshielded cable of the CAT5 category is used, and more often its improved version CAT5e. Cables of this category allow you to transmit a signal at a speed of 100 Mbit/s when using only two pairs (half) of wires, and 1000 Mbit/s when using all four pairs.

To connect to devices (routers, switches, network cards, etc.), 8-pin modular connectors, commonly called RJ-45 (although their correct name is 8P8C), are used at the ends of the twisted pair cable.

Depending on your desire, you can either buy ready-made (with crimped connectors) network cables of a certain length, called “patch cords”, at any computer store, or purchase twisted pair cables and connectors separately, and then make your own cables of the required size in the right quantity. You will learn how this is done in a separate material.

Using cables to connect computers into a network, of course, you can connect them directly from switches or routers to the connectors on the PC’s network cards, but there is another option - using network sockets. In this case, one end of the cable is connected to the switch port, and the other to the internal contacts of the socket, into the external connector of which you can subsequently connect computer or network devices.

Network sockets can be either built into the wall or mounted externally. Using sockets instead of protruding cable ends will give a more aesthetically pleasing look to your workspace. It is also convenient to use sockets as reference points for various network segments. For example, you can install a switch or router in the hallway of an apartment, and then thoroughly route cables from it to sockets located in all the necessary rooms. Thus, you will receive several points located in different parts of the apartment, to which you can at any time connect not only computers, but also any network devices, for example, additional switches to expand your home or office network.

Another little thing that you may need when building a cable network is an extension cord that can be used to connect two twisted pairs with already crimped RJ-45 connectors.

In addition to their intended purpose, extension cords are convenient to use in cases where the end of the cable ends not with one connector, but with two. This option is possible when building networks with a capacity of 100 Mbit/s, where it is enough to use only two pairs of wires to transmit a signal.

You can also use a network splitter to connect two computers to one cable at once without using a switch. But again, it is worth remembering that in this case the maximum data exchange speed will be limited to 100 Mbit/s.

For more information about crimping twisted pair cables, connecting sockets and the characteristics of network cables, read the special material.

Now that we've become familiar with the basic components of a local area network, it's time to talk about topology. In simple terms, a network topology is a diagram that describes the locations and methods of connecting network devices.

There are three main types of network topologies: Bus, Ring and Star. With a bus topology, all computers on the network are connected to one common cable. To unite PCs into a single network using the “Ring” topology, they are connected in series, with the last computer connecting to the first. In a star topology, each device is connected to the network through a special hub using a separate cable.

Probably, the attentive reader has already guessed that to build a home or small office network, the “Star” topology is predominantly used, where routers and switches are used as hub devices.

Creating a network using the Star topology does not require deep technical knowledge and large financial investments. For example, using a switch that costs 250 rubles, you can connect 5 computers into a network in a few minutes, and using a router for a couple of thousand rubles, you can even build a home network, providing several dozen devices with access to the Internet and local resources.

Another undoubted advantage of this topology is good expandability and ease of upgrading. Thus, network branching and scaling is achieved by simply adding additional hubs with the necessary functionality. You can also change the physical location of network devices or swap them at any time in order to achieve more practical use of the equipment and reduce the number and length of connecting wires.

Despite the fact that the Star topology allows you to quickly change the network structure, the location of the router, switches and other necessary elements must be thought out in advance, in accordance with the layout of the room, the number of devices being connected and how they are connected to the network. This will minimize the risks associated with purchasing unsuitable or redundant equipment and optimize the amount of your financial costs.

Conclusion

In this material, we examined the general principles of building local networks, the main equipment that is used and its purpose. Now you know that the main element of almost any home network is a router, which allows you to network many devices using both wired (Ethernet) and wireless (Wi-Fi) technologies, while providing them all with an Internet connection through one single channel.

Switches, which are essentially splitters, are used as auxiliary equipment for expanding connection points to a local network using cables. To organize wireless connections, access points are used, which allow, using Wi-Fi technology, not only to connect all kinds of devices wirelessly to the network, but also to connect entire segments of the local network together in a “bridge” mode.

To understand exactly how much and what kind of equipment you will need to purchase to create a future home network, be sure to first draw up its topology. Draw a diagram of the location of all devices participating in the network that will require a cable connection. Depending on this, select the optimal location for the router and, if necessary, additional switches. There are no uniform rules here, since the physical location of the router and switches depends on many factors: the number and type of devices, as well as the tasks that will be assigned to them; layout and size of the room; requirements for the aesthetic appearance of switching nodes; possibilities for laying cables and others.

So, as soon as you have a detailed plan for your future network, you can begin to select and purchase the necessary equipment, install it and configure it. But we will talk about these topics in our next materials.