What is a KVM switch? Its connection diagram. Connection options for ATEN KVM switches - cascade or shelf connection Control and indication

The need to control several computers at once from one set of keyboard and mouse often arises in work environments. This is what they are used for KVM switches(“Keyboard, Video, Mouse”). In recent years, such switches have been replaced by numerous programs that allow you to do the same through local network or the Internet, but switches are still used where maximum reliability is needed - software can sometimes fail.

KVM switches are used both in offices (desktop models) and in server rooms (models for server racks). Pick up correct model- is not as simple as it seems at first glance.

In the next section we will look at the most important characteristics KVM switches, and then we will present to your attention several models that can be purchased in our catalog stores.

Key Features You Should Pay Attention to

The scope of its application depends on the design of the switch housing. For offices, they buy desktop models that do not take up much space and are designed for 2-4 machines (both regular PCs and servers that are not located in a rack).

KVM-over-IP - switches that allow you to control your PC via global network Internet. This is a separate category, which has not been so popular lately due to the fact that similar functionality is available in the servers themselves.

A KVM extender is two devices (one on the computer side, the other on the peripheral side) that allow control remotely, but not via the Internet or local network.

A KVM console is a special device for server rooms, which when folded takes up 1U in a rack. When unfolded, it consists of a screen, keyboard and touchpad (or other device that replaces a mouse).

Also, the most powerful and multifunctional switches are installed in server racks - for 8 or more machines. They do not have a screen or keyboard; to connect them, the server cabinet must have additional shelves.

Number of connected computers

The main characteristic of any KVM switch. The more computers you can connect to it, the more expensive it will be, and the dimensions of the device will be larger. If you are choosing a model for the office, then 2 or 4 connections will probably be enough (the ports to which computers are connected are called “console ports”). If we are talking about use in a server room or server room, then the limit does not exist.

Supported Monitor Resolution

Be sure to make sure that the switch you purchase supports the resolution of the monitors that will be used in conjunction with it. With modern models this problem disappears, but keep in mind that switches are not designed for monitors high resolutions(for example, 4K).

Console connections

First of all, you need to determine which computers with which video outputs will connect to the KVM switch. These can be VGA (analog and legacy; maximum resolution - 1280x1024 pixels), DVI (digital; up to 1920x1080 pixels) DisplayPort or HDMI (digital; up to 2560x1440 pixels).

Next, you need to pay attention to the keyboard and mouse ports. The best option- USB, but if the server or computer has PS/2 ports, they will also work. Please note that most models do not work with wireless peripherals.

More advanced and expensive KVM switches allow you to connect not only computers, but also other devices - printers, audio devices, modems, removable drives and so on. For this, USB ports, 3.5 mm audio outputs and audio inputs, as well as various interfaces such as RJ-45 or RS-232 are used.

Control and display

Typically, the switch is controlled using one button on the case or remote control, which alternately changes the active console port. More advanced models have separate buttons for each port. Special indicators indicate the port that is active at a particular moment.

Nutrition

Based on the type of power supply, KVM switches are divided into passive and active. Passive models receive power from the keyboard and mouse interfaces. Sometimes they may simply not work due to lack of power, but in recent years this problem has been extremely rare.

Active KVM switches use their own power adapter, which is included in the kit. This is a more reliable, but also more expensive option - only server switches are usually equipped with their own adapter.

With the arrival of broadband Internet in offices, full-fledged remote administration has become possible. Thanks to this technology, service organizations were able to significantly reduce the response time to a client request, and system administrators got the opportunity to provide support even while outside the office. But the tools remote administration work only after the OS boots, if for some reason this is impossible, the physical presence of a specialist will be required. KVM over IP switches can solve this problem.

All administrators probably know what KVM switches are; this is a device that allows you to use one console (monitor, keyboard and mouse) to control several PCs. KVM switches can be as simple as those designed for personal use:

Also for rack mounting, supporting cascading and allowing immediate control a large number servers (up to several hundred) from one place:

What stands out in this company are KVM over IP switches, which allow you to access the PC console from anywhere via the TCP/IP protocol. For a long time These devices were considered “luxury items”, but recently offers have appeared on the market at a very reasonable price, making them quite affordable for small organizations.

Let's look at the capabilities of a KVM over IP switch using an example ATEN ALTUSEN KH1508i costing 727 USD. Except attractive price this device allows you to control up to 256 PCs (when cascading switches), supports PC, Mac, Sun platforms, PC connections via PS/2 and USB.

The switch is made in 1U format and can be rack mounted. The front panel contains output switching buttons, an active port indicator, a connector for firmware updates, a power indicator and a Reset button.

Another feature of the switch is the use of twisted pair UTP 5e to connect managed PCs, which allows them to be placed at a distance of up to 40 m. Now there is no problem connecting servers located in the next rack (or on the floor below) and there is no need to rack your brains over purchasing and laying expensive specialized cables. Connectors for connecting controlled PCs, network, slave switches and the console are located on the back of the switch:

To connect managed PCs, client modules are used that emulate the necessary peripherals. Emulation is performed directly by the module, regardless of the presence of a control device. This means that if you forget to turn the switch on, your managed PCs will still detect your keyboard, mouse, and monitor when they boot up, and you won't have to reboot them to gain access.

The manufacturer offers a wide selection of client modules for controlling computers of different platforms; two types of client modules are available for PCs: KA9520 (PS/2) and KA9570 (USB) costing 71 USD. Each module is a controller with an RJ-45 interface and a half-meter cable with VGA and PS/2 (USB) connectors, has its own firmware, regularly updated by the manufacturer, and there is a switch on the module body that switches it to firmware update mode. The KA9520 module is shown below:

For mounting on a vertical surface, a special basket is supplied with the module.

Switch settings are made via OSD menu or web interface (to a somewhat limited extent). If you don't have Mac computers or Sun, then all settings will be available via the web (by default, all switch ports are configured for the PC platform).

The connection to the device is made via the secure HTTPS protocol, despite the fact that the switch accepts connections on port 80, it is still redirected to the secure connection (port 443). Port 9000 is used to transfer data between the switch and the client program; this should be taken into account when forwarding ports (i.e., in addition to 80 and/or 443, you also need to forward 9000).

Let's move on to network functions switch, by default it is configured to receive settings via DHCP, which, in our opinion, is much better than a pre-set IP, just look at what address is assigned to the device in DHCP settings server and reserve it for the corresponding MAC address (indicated on the device body).

To access, you can use any browser (optimally IE), the web interface is not rich in settings, you can launch Windows (only through IE) or a Java client, or download them if you can’t launch them through the browser in any way.

The parameter deserves special attention Network Transfer Rate, for comfortable work with the device, you should specify the minimum guaranteed speed of the channel through which the switch is accessed.

To access managed PCs, you must run the client. We were unable to run the Windows Client on Windows 7 64-bit; in this case, the Java client, which runs on any platform with Java support, helps out. Already at the client we can produce more fine tuning devices:

To go to managed devices bookmark is used Main, which displays all client modules connected to the switch (or chain of switches):

At correct setting data transfer speed, working through a remote client is quite comfortable; the only drawback is some (sometimes significant) lag of the mouse cursor on the remote system from the cursor on the control PC.

However, it should be remembered that working via KVM Over IP is required mostly in emergency situations when control at the PC load level is required; in other cases it will be much more comfortable to work via RDP. If you are using a USB module (KA9570), make sure that the USB support keyboard and mouse to avoid unpleasant surprises.

We also recommend that you configure the server BIOS to turn on a signal from the keyboard or via the network. This will allow you to turn on the server remotely if you suddenly turn it off by mistake or one of your overzealous employees turns it off.

KVM over IP switches allow the administrator to gain almost complete control over the managed PC from anywhere in the world, provided there is Internet access. And what seems at first glance is relatively high price The device is more than compensated for by the capabilities it provides. In any case, it is worth calculating what will cost less, a KVM IP switch or the downtime of the enterprise required for the arrival of a technician.

If you have already been using it for a long time personal computer, then you have to periodically update not only software, but also the hardware, that is, the computer itself. What to do with the old one? Especially if all that remains is the system unit (the monitor has “moved” to a new one). The “486DX33”, purchased ten years ago, which was then the latest achievement of technology, is now impossible to sell.

Yes, it’s a pity, because during his long (by computer standards) life he managed to acquire microcontroller programmers and EEPROMs; various amateur radio and radio engineering programs are installed on it (and work well). It’s just that it’s not suitable for working on the Internet (that’s why a new one was purchased).

Installing this entire “architecture” on a new one is problematic - there are not enough COM and LPT ports (the old one had three COM and two LPT), and with USB ports nothing new from the old peripherals can work. So it was decided to keep two system units and two mice.

And switch between the monitor and keyboard. Moreover, for these purposes there are (disgusting, as it turned out) workplace switches on sale.

The purchased “Maxtro” mechanical workstation switch worked for no more than a month. Then the tricks started - the keyboard didn’t work correctly, or the monitor didn’t have all the colors. You have to constantly move its handle, push it, in order to catch the moment when everything will work normally.

After much torment with it, it was decided to make a homemade switch of workplaces, but not on a Taiwanese “galetnik”, the contacts of which were simply peeling off, but on Soviet RES-22 relays, controlled by two buttons.

Surprisingly, Maxtro switched all the contacts of the keyboard and monitor connectors, which is why it had so many contacts. In fact, for such switching, seven contact groups are enough, because all the “GNDs” can be connected together, and the keyboard power can be switched with two diodes. Each RES-22 has four contact groups, therefore, there is even one of them left, which can be used to control the relays themselves (relay trigger effect).

Schematic diagram

The circuit is made in such a way that it recognizes the switched on computer 2 by the +5 V supply voltage supplied to the keyboard. If you turn on computer 2, then +5V voltage will flow through capacitor C2 to the base of transistor VT1, which will open and turn on the relay.

It is self-locking free contact group K1.4 and after charging is completed, C2 will remain on. In this state, the keyboard and monitor will switch to computer 2. In the de-energized state, the keyboard and monitor will switch to old computer 1.

Rice. 1. Schematic diagram Switch consoles.

All details are collected in iron case from the "Maxtro" switch. "Mice" are used separately for each computer. The switch is powered by network adapter from a faulty printer.

The problem of switching a printer between two computers has been solved differently. The printer (Samsung 1210) has two ports - LPT and USB. LPT port connected to old system unit, and USB - to the new one.

KVM over IP - what is it?

KVM(or kvm over ip) is a device that allows you to transmit video signals and mouse/keyboard input over a network using the IP protocol from your server. Using KVM, you can reboot the server, access the server's BIOS, and other functions that cannot be performed on the server through a terminal. You can connect KVM access for free on the services page.

KVM is provided free of charge for the first two hours of the day. Subsequent fee KVM connection amounts to 30 minutes - 300 rubles.

How to connect KVM to the server?

Ready! You will receive KVM access to the server for a selected period of time (up to 2 hours). Within 15-20 minutes, access will be sent to your contact e-mail.

KVM doesn't work

Working through utilities

When working through utilities, there is no need to configure Java.
To manage KVM, Windows users can use the following utilities:

• CN8000 WinClient
• — for KVM from the manufacturer ATEN;
• — for KVM from the manufacturer ATEN;
• KVM Vision Viewer - for KVM from other manufacturers.

Working in the browser

To work with KVM, the browser must support Java. Opera and Chrome browsers (starting from Cromium 42) and the standard edition of Firefox (versions above 52) no longer support Java. Of the updated browsers, Java support is in Firefox ESR (until March 2018).

The operation of the web interface for KVM CN8000A models is guaranteed only in browsers based on the Gecko engine (for example, FireFox). In Webkit (Chromium and those based on it) there may be problems with displaying elements. In this case, we recommend using Windows or Java clients.

If the KVM console has a black screen, the message “No Signal”

In case of prolonged inactivity, the screen will turn off (the message “No Signal” will appear); to resume, you must press any key in the console (we recommend pressing “Alt” or “Ctrl” instead of “Enter” to avoid executing the command typed in the console earlier).

Keyboard not working in KVM console

Try resetting the KVM device. To do this, log in to the KVM web interface, go to the “Maintenance” section and perform a reset. Usually this item is called “Unit Reset”, “Reset USB”. 2 minutes after the reset, check the operation of the keyboard in the KVM.

What to do if the KVM window in Java does not open

If the KVM window does not open for a long time, check whether Java is installed on your PC. Go to the official Java website, then click on the link “Do I have Java software installed on my computer? " If Java is installed, then follow the instructions below.

If Java version 8 is installed

To launch the KVM console you need to complete three steps:

1. 1.

   Make changes to the file java.security. The file is located in JDK_HOME/jre/lib/security/java.security, usually these are the paths:
   

   for Windows OS:
   C:\Program Files\Java\jre1.8.0_91\lib\security for 64-bit JAVA versions or
   C:\Program Files (x86)\Java\jre1.8.0_91\lib\security for 32-bit versions.
   

   for Linux OS:
   /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/security/java.security
   or you can find the file with the command in Linux consoles:
   find /usr/lib/ -name java.security
   

   In this file you need to comment out the line that begins with:

   jdk.certpath.disabledAlgorithms
   those. add a "#" symbol at the beginning of the line, for example:
   # jdk.certpath.disabledAlgorithms=MD2, RSA keySize

   Please note that to edit a file java.security need to run text editor as administrator (for Windows) or super root user(for Linux).

If the problem persists, try installing Java 7 and setting the security level to Medium (see above).

If the methods listed above did not help you and any error messages appear when opening the KVM window, you should refer to the official JAVA manual on the developer’s website: http://java.com/en/download/help/

As a solution, try using Windows OS and Internet browser Explorer versions 9.
It is also possible to work in Linux systems x32 at using Firefox and 7 versions of Java.
Additionally, you can use the emulation mode for older browsers in Internet browser Explorer 11 (accessible by pressing the F12 button).

What to do if a KVM window in Java opens from the browser, but there is an error in the status bar?

Information about blocking messages Java works in the browser is located at the link.

What is IPMI and why is it needed?

IPMI- interface for remote control server. It is designed for autonomous monitoring and management of functions built into the server hardware.

IPMI operates regardless of the operating system on the server. Therefore, if problems are detected with the processor / BIOS / operating system, you can reboot the server and restore critical management, logging and inventory functions via IPMI. You can read more about IPMI on thematic forums.

IPMI Interface Access

If you have problems with console display and IPMI availability, use the instructions: . If any difficulties arise, write.

Installing an operating system using IPMI

You can install the operating system yourself using IPMI. The IPMI interface allows you to remotely install the OS and connect the image file as a virtual DVD-ROM on the server.

The following images are available for loading into IPMI:

• Centos 6, 7;
• Debian 8, 9;
• Ubuntu 14, 16, 18;
• ESXI 6.5, 6.7;
• SystemRescueCd 5.3.2.

If you need to download another image, please write with a link to the image.

To install the operating system, follow these steps:

1. 3.

   On the Manage tab, click IPMI Console:

2. 4.

   On first transition confirm launch:

   • in the first pop-up window, check the box next to “Always trust content from this publisher” and click the button Run:
   • in the second pop-up window click the button Yes:
3. 5.

   In the Web IPMI window, select Virtual Media — Virtual storage:

4. 6.

   In the “Logical Drive Type” field, select the image type ISO File, in the “Image File Name and Full Path” field, select the distribution file (any .iso file), click Plug in, Further OK:

5. 7.

   Reboot the server in the console window Macro — Macro — Ctrl+Alt+Del:

6. 8.

   After this, the “Virtual DVD” device will appear in the server BIOS, which can be set first in the boot order of disks ( Boot priority):

7. 9.

   Save changes by selecting "Save changes and exit" in the "Exit" menu:

8. 10.

   Boot from the virtual DVD and install the operating system.

If you have problems with console display and IPMI availability, use the instructions: . If any difficulties arise, write.

It is important to know

The IPMI controller forwards to motherboard virtual DVD-ROM and keyboard control via the USB bus, so you cannot disable support for USB devices in the BIOS or OS.

What to do if IPMI does not work?

Ways to solve IPMI console display problems (for example, black screen):

Press any key on the keyboard (for example, Shift). If your keyboard doesn't work, use the virtual keyboard.

For a server with operating system Ubuntu - Press keyboard shortcut Ctrl + Alt + F1.

Reboot IPMI (cold reset) by connecting to the server via SSH as root and running the command: ipmicfg -r or ipmitool bmc reset cold .

The ipmitool utility requires some kernel modules; you can enable them using the command in the server console from the root user: modprobe ipmi_si && modprobe ipmi_devintf && modprobe ipmi_msghandler.

• For a server with operating system Windows system Server - connect as the Administrator user and in command line enter the command: ipmicfg-win.exe -r .

If the above methods do not resolve the issue, follow these steps:

Connection failed error

Reset IPMI. For this:

Keyboard doesn't work

If the IPMI console still does not respond to keyboard inputs, use the virtual keyboard.

From the Virtual Media menu, select Virtual Keyboard:

To return to physical keyboard control in the IPMI console, select the Options menu item. Keyboard Mouse Hotplug:

If you need to hide virtual keyboard, in the “Exit” menu, select Exit:

After that, close the IPMI console and open it again. The IPMI reboot may take up to five minutes.

If any difficulties arise, write.