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Remote Wake-Up: Intel® Network Adapters User Guide

About Remote Wake-up
Physical Installation Issues
BIOS Settings
Operating System Settings

About Remote Wake-up

The ability to remotely wake servers is an important development in server management. This feature has evolved over the last few years from a simple remote power-on capability to a complex system interacting with a variety of device and operating system (OS) power states.

Supported Adapters

Wake on Magic Packet

In early implementations of Remote Wake-up, the server could be started from a power-off state by sending a Magic Packet*. A Magic Packet is an Ethernet packet that contains an adapter's MAC address repeated 16 times in the data field. When an adapter receives a Magic Packet containing its own MAC address, it activates the server's power. This enables network administrators to perform off-hours maintenance at remote locations without sending a technician out.

This early implementation did not require an OS that was aware of remote wake-up. However, it did require a server that was equipped with a standby power supply and had the necessary circuitry to allow the remote power control. These servers were typically equipped with a feature named APM (Advanced Power Management). APM provided BIOS-based power control. 

APM Power States
Power State Description
Ready On and fully operational
Stand-by CPU is idle, and no device activity has occurred recently
Suspended System is at the lowest level of power consumption available that preserves data
Hibernation Power is off, but system state is preserved
Off Power off

Advanced Configuration and Power Interface (ACPI)

Newer computers feature ACPI (Advanced Configuration and Power Interface), which extends the APM concept to enable the OS to selectively control power. ACPI supports a variety of power states. Each state represents a different level of power, from fully powered up to completely powered down, with partial levels of power in each intermediate state. 

ACPI Power States
Power State  Description
S0 On and fully operational
S1 System is in low power mode (sleep mode). The CPU clock is stopped, but RAM is powered on and being refreshed.
S2 Similar to S1, but power is removed from the CPU.
S3 Suspend to RAM (standby mode). Most components are shutdown. RAM remains operational.
S4 Suspend to disk (hibernate mode). The memory contents are swapped to the disk drive and then reloaded into RAM when the system is awakened.
S5 Power off

Some newer ACPI-aware operating systems, such as Microsoft Windows* 2000 and Windows Server 2003, do not support remote wake-up from a powered off state (S5). These operating systems do support remote wake-up from intermediate states like standby and hibernate mode (S3 and S4).

NOTE: S4 is the only ACPI mode currently supported by Dell.

Remote wake-up can be initiated by a variety of user selectable packet types and is not limited to the Magic Packet format. For more information about supported packet types, see the operating system settings section.

See the System Documentation for information on supported power states.

Wake Up Address Patterns

The wake up capability of Intel adapters is based on patterns sent by the OS. You can configure the driver to the following settings using Intel PROSet for Windows. For Red Hat Linux, WoL is provided through the Ethtool* utility. For more information on Ethtool, see the following Web site:

Choosing "Directed Packets" will also allow the adapter to accept patterns of the Address Resolution Protocol (ARP) querying the IP address assigned to the adapter. If multiple IP addresses are assigned to an adapter, the operating system may request to wake up on ARP patterns querying any of the assigned addresses. However, the adapter will only awaken in response to ARP packets querying the first IP address in the list, usually the first address assigned to the adapter.

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Physical Installation Issues


Some motherboards will only support remote wake-up (or remote wake-up from S5 state) in a particular slot. For example, the Intel Desktop Board D815EPEA2 only supports remote wake-up from a powered off (S5) state if the adapter is plugged into PCI slot 2. It does, however, support remote wake-up from standby from any slot. See the documentation that came with your system for details on remote wake-up support.


Newer Intel PRO adapters are 3.3 volt, but will work in a 5-volt slot also. They are keyed to fit either type of slot.

The 3.3 volt standby supply must be capable of supplying at least 0.2 amps for each Intel PRO adapter installed. Turning off the remote wake up capability on the adapter using the IBAUTIL utility reduces the power draw to around 50 milliamps (.05 amps) per adapter.

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BIOS Settings

You may need to configure various settings in the computer BIOS so that remote wake-up will work.

Many ACPI computers can be configured to work in APM mode. Check your BIOS settings to determine which mode you are operating in.

In both APM and ACPI computers, you may find settings for Wake on LAN* under the Power Control area and titled "Wake on LAN" and/or "Wake on PME". Wake on LAN refers to wake up events received through a 3-pin header cable. Wake on PME refers to wake up events received through the PCI bus. To enable remote wake-up, you should enable the setting that corresponds to your adapter connection.

In ACPI computers operating in ACPI mode and using an ACPI-aware operating system, look for an ACPI-specific setting. If you want to power up the system from a power off state, set an ACPI-specific setting such as "Wake on LAN from S5" to enable.

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Operating System Settings

Microsoft Windows Products

Windows 2000 and Windows Server 2003 are ACPI-capable. These operating systems do not support remote wake-up from a powered off state (S5), only from standby. When shutting down the system, they shut down ACPI devices including the Intel PRO adapters. This disarms the adapters' remote wake up capability. However, in some ACPI-capable computers, the BIOS may have a setting that allows you to override the OS and wake from an S5 state anyway. If there is no support for wake from S5 state in your BIOS settings, you are limited to wake from standby when using these operating systems in ACPI computers.

The advanced settings tab in Intel PROSet includes a setting called Enable PME for some adapters. To explicitly allow wake up with a Magic Packet from shutdown under APM power management mode, set this to Enable. See Intel PROSet help for more details. 

In ACPI-capable versions of Windows, the Intel PROSet advanced settings include a setting called Wake on Settings. This setting controls the type of packets that wake up the system from standby. See Intel PROSet help for more details.

In ACPI computers running ACPI-aware operating systems, make sure the wake on standby option is enabled. To enable wake on standby, open the Device Manager and then navigate to the adapter properties tab's Power Management setting. Check the setting Allow this device to bring the computer out of standby.

Other Operating Systems

Remote Wake-Up on is also supported in

In operating systems that do not support remote wake-up technology, you can still use the Magic Packet method to remotely power up a computer. When the server is first powered on, the Intel Boot Agent configuration utility can be invoked by typing CTRL-S when the Boot Agent prompt appears on the screen. The configuration program has a parameter setting called Legacy OS Wakeup Support. If this setting is enabled, the Boot Agent will pre-condition the adapter to respond to a Magic Packet wake up event. This allows remote wake-up in operating systems that do not support it.

Please read all restrictions and disclaimers.

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