Networking Connectivity
Network Connectivity
Understanding WOL

Symptom(s):
N/A

Cause:
N/A

Solution:
WOL, stands for Wake-On-LAN or the remote boot-up of computers.

The system could be started from a power off state by sending a "Magic Packet*." The Magic Packet contained the adapters MAC address repeated 16 times in the data field. The adapter, which was supplied with power from a standby power supply when the computer was turned off, would react to a "Magic Packet" containing its own MAC address by toggling a signal connected to the computer power control circuitry. The power control circuitry, in response, would activate power to the computer resulting in the computer booting the OS. This allowed network administrators to perform off-hours maintenance at remote locations.

This requires a computer to be equipped with a standby power supply with the circuitry to allow remote power control. (typically equipped with a feature named APM (Advanced Power Management).

Newer computers feature ACPI (Advanced Configuration and Power Interface), which extends the APM concept to allow the OS to selectively control power. ACPI supports a variety of power states, representing different levels of power states. A quick synopsis:

S0

On and fully operational.

S1

System is in low power mode (a.k.a. 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 (a.k.a. standby mode). Basically, most components are shutdown except RAM.

S4

Suspend to disk (a.k.a. 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* 98, Windows* Me, Windows* 2000 and Windows* XP, support remote wake-up from standby or hibernate mode. Remote wake can be initiated by a variety of user selectable packet types.

Wake on LAN* (WOL) Cable
This cable is required on all remote wake-up capable adapters when used in older wake on LAN capable computers. These computers are generally equipped with a PCI 2.1 compliant bus, and the BIOS is typically designed for APM compliant power management.

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 will still be needed for older 82558-based Intel® PRO/100+ Management adapter model numbers PILA8900 AND PILA8461. These computers will not need the WOL cable with the later Intel 82559 or 82550 based adapter models PILA8460B, PILA8470B, PILA8464B, PILA8474B, PILA8464BUS, PILA8474BUS, PILA8460C3 and PILA8470C3.


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 will only support remote wake-up from an S5 state if the adapter is plugged into PCI slot 2. It will, however, support remote wake-up from standby from any slot. See documentation.

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

In both APM and ACPI computers, you may find settings for Wake on LAN*, generally 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 the your adapter connection (e.g. set Wake on LAN to "enable" if you are using the WOL cable).

In ACPI computers, if you are using an ACPI aware OS (such as Windows 2000), and wish to be able to power up the system from a power off state, look for an ACPI specific setting such as "Wake on LAN from S5" and enable it.

Microsoft Windows Products
Microsoft Windows NT and Windows* 95 are not ACPI capable. Microsoft Windows 98, Windows Me, Windows 2000 and Windows XP are ACPI capable. These operating systems do not support wake from S5 state, only from standby. In some ACPI capable computers, the BIOS may have a setting that allows you to wake from an S5 state anyway. If there is no support for wake from S5 state in your BIOS settings, then you will be limited to wake from standby when utilizing these operating systems in ACPI computers.

In the adapters advanced settings, there is a setting titled "Enable PME." To explicitly allow wake up with a Magic Packet from shutdown under APM power management mode, set this to "Enable." This only applies to Intel 82559 and 82550 based adapters (PILA8460B, PILA8470B, PILA8464B, PILA8464BUS, PILA8474B, PILA8474BUS, PILA8460C3, PILA8470C3). See PROSet help for more details. In ACPI computers running ACPI aware operating systems such as Windows 2000, in Device Manager, the adapter properties will display a tab titled "Power Management." The setting "allow this device to bring the computer out of standby" should be checked.

Other Operating Systems
In operating systems that do not support remote wake-up technology, you can still utilize the "Magic Packet" method of remotely powering up a computer. When the computer is first powered on, the Intel® Boot Agent configuration utility can be invoked by entering CTRL-S when the Boot Agent prompt appears on the screen. The configuration program has a parameter setting titled "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.

 

This applies to:

Intel® PRO/100 S Dual Port Server Adapter
Intel® PRO/100 S Server Adapter
Intel® PRO/100+ Dual Port Server Adapter
Intel® PRO/100+ Server Adapter
Intel® PRO/1000 CT Network Connection
Intel® PRO/1000 MT Desktop Adapter
Intel® PRO/1000 T Desktop Adapter

Solution ID: CS-000084
Last Modified: 07-Oct-2013
Date Created: 02-Jul-2002
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