Also, because a Magic Packet is specific to the MAC address of a network adapter, a Magic Packet is unlikely to be sent accidentally. Magic Packets are especially designed to wake up a computer from a power-saving state. In this situation, we strongly recommend that you configure the computer to wake only in response to Magic Packets. One cause may be that the network environment generates wake-up patterns too frequently. For example, the computer may wake up soon after it enters a power-saving state. However, unwanted wake events may occur after you enable WOL. WOL can be an effective way to conserve power while keeping a computer reachable on the network.
Therefore, by default, WOL is disabled in Windows 7 and in Windows Vista. These unwanted wake-up events may occur in especially noisy environments such as enterprise networks. However, in some networks, network traffic may wake up a remote computer by mistake.
Such protocols do not use these packets to wake computers. For example, routers use ARP packets to periodically confirm the presence of a computer. However, some networking protocols use these packets for other purposes.
In most cases, a wake-up pattern or a Magic Packet enables remote access to a computer that is in a power-saving state.
This article explains why unwanted wake-up events occur when you enable the Wake On LAN (WOL) functionality in Windows 7 and in Windows Vista, and describes how to configure the computer to wake only in response to a Magic Packet.Īpplies to: Windows 7 Service Pack 1 Original KB number: 941145 Introduction