One embodiment of the present invention provides a system that wakes up a sleeping target system located on a target LAN (Local Area Network) from a remote system located on a remote LAN. Because the sleeping target system is in a sleep state, it receives packets of a lower-layer protocol which cannot be used by the remote system to directly send packets to the sleeping target system. During operation, the remote system creates a wake-up packet. The remote system then uses a second protocol to send the wake-up packet to a relay agent located on the target LAN. Upon receiving the first wake-up packet, the relay agent uses the lower-layer protocol to send a second wake-up packet to the sleeping target system, which causes the sleeping target system to wake up.