Wake-on-LAN (WOL) is an Ethernet standard that allows a machine to be awakened when a specific network message is received. In order for WOL to function, the machine BIOS/UEFI must be configured to do so, the network card must support it, the operating system must place the machine in the appropriate power state, and the correct packet must get to the device. For more information on how to configure the machine or operation system for WOL, check with your hardware or OS vendor. After configuring the machine, review the considerations described in this section to ensure that the WOL message can be sent to the device.
ZENworks implements the WOL standard message format (referred to as the magic packet), which consists of a packet destined to the subnet broadcast address and contains the Mac address of the device to be awaked. In order for this magic packet to reach the device, one of the following must be true:
The Primary Server and the managed devices being awakened must be on the IP subnet, such that the device will receive subnet broadcasts.
The Primary Server and the managed devices being awakened are on separate IP subnets, but the router or switch has been configured to forward subnet broadcasts sent by the server to the subnets where the managed devices exist.
The Primary Server and the managed devices being awakened are on separate IP subnets. The the router or switch is not configured to pass subnet broadcasts, but a Satellite Server exists on the subnet. In this case, you can configure the satellite device to act as a WOL proxy to wake up the devices on its subnet.
The Primary Server and the managed devices being awakened are on separate IP subnets. The router or switch is not configured to pass subnet broadcasts and no Satellite Server exists on the subnet. Ensure that at least one managed device is running on the subnet where the target machine exists so that the device can be used as a WOL proxy. In this case, the Primary Server sends a unicast message to the proxy so that it can send the magic packet on its behalf.
If you are a ZENworks administrator and want to wake up all the devices that are inside a folder named IT users, consider following questions before configuring the WOL feature (in ZENworks) to wake up the devices:
Are all the devices in the folder that you want to wake up in the same subnet?
How many Primary Servers are available in the zone. Is there is a Primary Server on each subnet?
Is there is a Satellite Server on each subnet in the zone?
With a proper understanding of your network topology, the WOL will function as described below:
Devices in the folder that are to be awakened are on the same subnet along with a Primary Server: If devices in the folder that are to be awakened are on the same subnet and if there is a Primary Server available in the same subnet, then you need to select the Primary Server under the option Primary or Proxy Servers that send wake-up request to the managed devices.
Devices in the folder that are to be awakened are on different subnets: If devices in the folder that are to be awakened are spread across different subnets and if there is a Primary Server available in each of the subnets, you need to select all of the Primary Servers that are in those subnets in the WOL options. You can select the Automatically detect the primary server option in order to automatically detect the right Primary Server on the subnet, to send magic packets to the devices on that subnet.
No Primary Server on each of the subnets of the devices that are to be awakened: When there is no Primary Server on one or more of the subnets of the devices that are to be awakened, if the network infrastructure is configured in such a way that routers connecting networks are enabled to forward broadcast traffic, then the magic packets will reach the devices, and they are woken up. In most normal circumstances, routers are not configured to allow broadcast traffic in order to avoid network traffic collision and crippling of the network.
A Satellite Server present in each of the subnets in the zone: If there is a Satellite Server on each of the subnets in the zone, then you need to first identify Satellite devices in each subnet of the devices that are to be woken up. Next, select a Satellite device as a Proxy WOL sender. You can add one Satellite device per subnet in the list of those devices that send WOL packets. You can group devices that are to be woken up based mainly on the subnet. The proxy device in that subnet will be enhanced to send WOL packets to all the devices in that subnet. After the magic packet has been sent to the device, the boot-up time for each device might vary depending on the hardware and software products that are active during the startup.
ZENworks pings port 7628 after two minutes of sending the wake-up request to know if a device is active. On this port, on the managed device, the ZENworks agent service listens to service requests from the server to process quick tasks. If the device is up within 2 minutes, then the response is received and the device is up. If a device takes more time to come up, then the status is lost. For better results, configure the number of retries in the WOL option to be more than one. The recommended number of retries to be configured is at least three and the time interval between retries should be at least 3 minutes in the WOL options.