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Follow UsWake On LAN, or WOL for short, isn’t a new technology; it’s been around for some time, and is a part of Intel’s Wired for Management initiative. It enables you to remotely power on PCs and can be used in a number of situations. One situation is where, as the network administrator, you need to backup data from all the clients on your network. You can’t do it while the users are working on the client machines, as it would take a toll on the network’s bandwidth and bring it to a crawl. If you were to do it after everyone left, then you’d need to turn each PC on individually. That’s where WOL comes in handy. With it, you need to just send a ‘wake up’ call to all the PCs, take the backup and put them back to sleep.
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What you need
To use WOL, your network card and motherboard must support this feature. Your motherboard must also support ACPI (Advanced Configuration Power Interface), which will let you put your PC in sleep mode. Also, your network card must be connected to the motherboard through a small cable because when the network card receives a WOL request, it passes it on to the motherboard through this cable, which in turn is routed to the power supply to activate the PC. We used a P4-based machine having an Intel 850 motherboard and built-in LAN capability, so this cable was not necessary.
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You need a network card with WOL support such as this one from Intel. This cable connects to the WOL connector on the motherboard |
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The adapter also has two connectors, one for sending a WOL request to the motherboard and the other for receiving power from the power supply. Network cards with the WOL feature are available from most manufacturers, including Intel, IBM, Compaq, D-Link and 3Com. Most motherboards nowadays have this feature built-in.
Once you have installed your network card, you have to enable WOL from your PC’s BIOS. This might vary for different BIOSs. In our case, we had to go into the Power option from the BIOS menu, and enable ‘Power On’ for WOL and wake on PME (power management enabled). Save the settings and exit from the BIOS.
The configuration
We used Win 2000 Professional on the client machine. Here, once you’ve configured your network card’s drivers, go to your
network properties and click on the ‘Configure’ button next to your LAN card. Here, you’ll find a tab called ‘Power Management’. To enable your PC to a wakeup mode, check the box labeled ‘Allow this device to bring the computer out of standby’. Below this is another box for enabling power management, called ‘Allow the computer to turn off this device to save power’. Click on OK to finish.
Wake it up
You can ‘wake up’ a machine with WOL simply by pinging or accessing it from another machine on the network. You can also send wake-up frames or packets (also known as ‘magic packets’), which are specifically meant for WOL-enabled PCs. There are various utilities that let you send these WOL magic packets. However, since it works by simply accessing the WOL-enabled machine, you don’t really need these utilities. The WOL network
| Pluses The WOL feature can be quite beneficial if used right. For instance, if you have network-management software in place that allows you to access your network remotely over the Internet, you can manage individual PCs on your network over the weekend from your home. Even if you don’t have network-management software installed, you could manage all PCs from your seat instead of running around the building and turning them on. In both cases, you save a lot of time and effort. As you can do everything during off peak hours, your network-management tasks can be performed more efficiently since there’s very little network traffic. Minuses |
adapter on the client machine continuously monitors the network for wake-up frames, and powers on the machine as soon as it receives them. The system identification information (probably the IP address) is stored in the network card. Once the system is powered on, the scheduled tasks can be performed.
To test this feature, we used a backup software called Retrospect to backup data from a WOL-enabled machine. We scheduled the software to initiate a backup process from the server. The WOL machine automatically got powered ON and the backup process was initiated. Depending upon the time it takes to backup the data, you can configure the WOL machine to go back to sleep after a predefined time period.
Rashmi Sahu and Sanjay Majumder