How is a machine in sleep/hibernate mode identified on the network

[phealer]

hi,
can someone help me understand, how a machine Win7 or XP once goes to sleep/hibernate mode, can be identified on the network to do a Wake-On-LAN

Because the machine is shutdown, the ping does not give a response. In a DHCP environment, when the machine goes to sleep mode, the ip is released so not necessarily the machine can be identified with its IP.

thanks for any insight on this,

cheers,
Pradeep

 

[Dave Atkin]

This will probably explain it better than I could:

How-To Geek Explains: What is Wake-on-LAN and How Do I Enable It? - How-To Geek

 

[phealer]

Dave, this is useful information
Found this additional information


Unicast, as the transmission method for sending wake-up packets to a computer, uses the IP address of the target computer from hardware inventory to route to the target computer's subnet, and it uses the Media Access Control (MAC) address of the target computer from hardware inventory to construct the wake-up packet. When the wake-up transmission reaches the target computer's subnet, the wake-up packet is sent directly to the target computer.
If the target computer has changed its IP address since it last sent its inventory information, the wake-up packet will reach the wrong computer but it will not wake it up because the MAC address in the wake-up packet transmission will not match.
If you have computers that move between subnets, you might be able to reduce the likelihood of failed wake-up transmissions by increasing the Dynamic Host Configuration Protocol (DHCP) lease time and configuring the hardware inventory schedule to run more frequently.

Subnet-directed broadcasts, as the transmission method for sending wake-up packets to a computer, 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.