Patent ID: 7447927

Claim:
A method for waking up a sleeping target system located on a target LAN (Local Area Network) from a remote system on a remote LAN, wherein the sleeping target system receives packets of a first protocol which cannot be used by the remote system to send a packet directly to the sleeping target system because the remote system and the sleeping target system are on different LANs, the method comprising: creating a first wake-up packet, wherein creating the first wake-un packet involves determining an IP (Internet Protocol) address of a relay agent located on the target LAN based on an IP address of the sleeping target system and a subnet mask; and sending the first wake-up packet to the relay agent using a second protocol; wherein sending the first wake-up packet to the relay agent causes the relay agent to use the first protocol to send a second wake-up packet to the sleeping target system, which causes the sleeping target system to wake up; and wherein the first wake-up packet is a network-layer packet which includes a DHCP (Dynamic Host Configuration Protocol) reply packet whose header contains: a client hardware address field which is set to a link-layer address of the sleeping target system; a client IP address field which is set to a network-layer address associated with the link-layer address of the sleeping target system; and a relay agent network-layer address field which is set to a network-layer address associated with an interface of the relay agent which is coupled with the target LAN, wherein the relay agent located on the target LAN is a DHCP relay agent.