Yes, I once tried to implement a data-center-wide power management system based on Wake On Lan technology. I had a number of solutions, but never got to implement them because the data center people decided that the reliability costs involved in shutting down and powering back up were higher than the energy savings.
A couple of random observations:
My experience was that the routers forgot the mac addresses after the machines had been shut down for more than 20 minutes. After that, the mac addresses were lost until the machines next powered up. Obviously, this will vary depending on the actual router used, but 20 minutes is probably pretty typical.
This means that in practice, the only way to get the mac address is to obtain it BEFORE you shut the system down. I'm not sure what your application is, but I think you can probably find a way to do this one way or another.
Once the router has forgotten the mac address, there's no way to deliver the WOL packet to the machine to be woken from outside the network. From inside the network, you can still do it with a broadcast packet. Either way, you still need to know the mac address, since it's part of the WOL packet.
Now theoretically, you could modify the firmware in the NIC chip to allow it to respond to ARP packets even when the machine itself is powered off. This may even be common practice -- I don't know. If so, what you want to do is do-able, but would be highly dependent on the exact network interface you have.
answered 2012-12-06T01:04:18.860