Remote Wake-Up and Wake on LAN*

About Remote Wake-Up

The ability to remotely wake computers is an important development in computer 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.

NOTES:
  • Not all systems support every wake setting. There may be BIOS or Operating System settings that need to be enabled for your system to wake up. In particular, this is true for Wake from S5 (also referred to as Wake from power off).

 The following adapters do not support Wake on LAN* (WoL) operations

  • Intel® PRO/1000 MT Quad Port Server adapter
  • Intel® Gigabit VT Quad Port Server Adapter
  • Intel® Ethernet Server Adapter X520-2
  • Intel® Ethernet Server Adapter X520-1
  • Intel® Ethernet Server Adapter X540-T1
  • Intel® Ethernet Converged Network Adapter X540-T2
  • Intel® Ethernet Converged Network Adapter X540-T1

Wake on Magic Packet

In early implementations of Remote Wake-up, the computer 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 computer’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 computer that was equipped with a standby power supply and had the necessary circuitry to allow the remote power control. These computers were typically equipped with a feature named Advanced Power Management (APM). APM provided BIOS-based power control.

Advanced Configuration and Power Interface

Newer computers feature Advanced Configuration and Power Interface (ACPI), 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. Power states include:
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

Not all systems support being awakened from a powered-off state.

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.

Wake Up Address Patterns

The wake up capability of Intel gigabit adapters is based on patterns that are sent by the OS. You may configure the driver to the following settings using Intel® PROSet:

Choosing "Directed Packets" will also accept patterns of the Address Resolution Protocol (ARP) querying the IP address assigned to the adapter. Upon configuring multiple IP addresses to one adapter, the OS may request to wake up on ARP patterns to all of the configured addresses. The adapter will only awaken in response to ARP packets querying the first IP address in the list.

Physical Installation Issues

Wake on LAN Cable

For computers with a PCI 2.1 compliant bus

A Wake on LAN cable is required on all remote wake-up capable adapters when used in older WoL-capable computers. These computers are generally equipped with a PCI 2.1 complaint bus and the BIOS is typically designed for APM compliant power management.
NOTE:  Remote Wake-Up from power-off (S5) is not supported on the following adapters in computers using the PCI 2.1 bus. To use Remote Wake-Up on any of the adapters listed below, the computer must have a PCI 2.2 compliant bus.
  • Intel PRO/100+ PCI adapter (PILA8460BN)
  • Intel PRO/100 M Desktop adapter (PILA8460F)
  • Intel PRO/1000 T Desktop adapter (PWLA8390T)
  • Intel PRO/1000 XT Server adapter (PWLA8490XT)

For computers with a PCI 2.2 compliant bus

The Wake on LAN cable is not usually required for computers equipped with a PCI 2.2 compliant bus, as the wake up signal is routed through the PCI bus. This is done through the PCI connector pin defined as PME (Power Management Event).

Many of the newer ACPI computers also have a connector for the 3-pin Wake on LAN cable for backwards compatibility with older WOL capable adapters. In this type of computer, the WOL cable is still required for older 82558-based Intel® PRO/100+ Management adapter model numbers PILA8900 and PILA8461.

Slot

Some motherboards 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 or motherboard for details on remote wake-up support.

Power

Early versions of the Intel PRO/100+ Management adapter are +5 volt only. These models must have the 3-pin cable attached for the remote wake-up function to work. These adapters are equipped with 3 LEDs on the adapter bracket, whereas the PCI 2.2 compliant PRO/100 models have 2 LEDs on the adapter bracket. The older +5 volt model adapters are not compliant to the PCI 2.2 specification and do not fit in a 3-volt only PCI slot due to the slot being keyed differently.

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

If your computer requires the 3-pin cable, the +5 volt standby power supply must supply at least 0.2 amps at +5 volts for each adapter installed. For older PCI 2.1 compliant management adapters, the power supply must supply at least .6 amps. This value is usually listed on the power supply label as +5SB, +5VSB or +5AUX. 

If your remote wake-up enabled computer is compliant to PCI specification 2.2, it does not require the 3-pin cable for remote wake-up. In these computers, the 3.3 volt standby power supply must provide at least 0.2 amps for each adapter installed. You may need to contact your computer manufacturer to verify the standby current rating. Turning off the remote wake up capability on the adapter by using the IBAUTIL utility reduces the power draw to around 50 milliamps (.05 amps) per adapter.

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 setting refers to wake up events received through the 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. For example, set Wake on LAN to enable if you are using the WOL cable.

In ACPI computers operating in ACPI mode and using an ACPI aware OS, 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.

Last modified on 7/12/11 11:31p Revision