Subnet-directed broadcasts, as the transmission method for sending wake-up packets to a computer in a Configuration Manager 2007 site, uses the Media Access Control (MAC) address and IP subnet address of the target computer from hardware inventory. The wake-up transmission is sent to the computer's last known subnet, and it is then broadcast to all computers on that subnet. For this method to be successful, all intervening routers must be configured to forward subnet-directed broadcasts. During this broadcast, the computer that has the MAC address specified in the wake-up transmission will respond.

Because this transmission method uses the subnet address rather than the IP address, it will succeed if the target computer has changed IP addresses but remained in the same subnet. The use of subnet-directed broadcasts is the more traditional method of sending wake-up packets, so this transmission method might be more compatible with a wider range of computer network adapters than transmitting wake-up packets using unicast. However, subnet-direct broadcasts are not supported with IPv6, and are often disabled on routers.

If you are using subnet-directed broadcasts as the Wake On LAN transmission method, it is highly recommended you include the additional security measure of allowing only the Configuration Manager site server to send subnet-directed broadcast traffic using a non-default port number for the wake-up packets.

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