Architecture to enable energy savings in networked computers

A system comprising:

• a computer network;
• multiple computers coupled with the computer network;
• a network switch in the computer network;
• and
• a sleep manager computer system coupled with the computer network and configured to perform operations comprising:
• receiving, via the computer network, information regarding one or more of the multiple computers transitioning to a low-power mode of operation;
• sending at least one message over the computer network to cause the network switch in the computer network to change at least one assigned port for the one or more of the multiple computers, wherein the change allows network communications intended for the second computer to be forwarded to the first computer;
• receiving network communications designated for the one or more of the multiple computers, the network communications passing through the network switch;
• processing at least a portion of the network communications on behalf of the one or more of the multiple computers within one or more virtual machines that copy at least some functions of the one or more of the multiple computers;
• and
• initiating, via the computer network, a transition of the one or more of the multiple computers out of the low-power mode of operation when at least one of the network communications satisfies a predetermined condition.

A non-transitory storage medium encoding a program operable to cause computers to perform operations comprising:

• at a host computer, indicating a sleep mode to a sleep server and sending predetermined events and application triggers to the sleep server prior to entering the sleep mode;
• at the sleep server, responding to the host computer indicating a sleep mode by accepting events and application triggers;
• at the sleep server, for the host computer indicating the sleep mode, instantiating a new virtual-machine (VM) for the host computer and setting an address of a network interface of the VM to be the same as the host computer put to sleep;
• at the sleep server, using the VM to reply to predetermined requests as if the host computer was still awake and to awake the host computer for predetermined wake-up events.