Method and apparatus for waking up a sleeping system
View Patent ↗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. Note that, since 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. Note that using the upper-layer protocol enables the remote system to communicate with the relay agent even though they are on different LANs. 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. Recall that the remote system cannot use the lower-layer protocol to send a wake-up packet directly to the sleeping target system because the remote system and the sleeping target system are on different LANs. The remote system overcomes this limitation by first sending a wake-up packet to the relay agent using the upper-layer protocol, which causes the relay agent to send another wake-up packet to the sleeping target system using the lower-layer protocol.
1. 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.
2. The method of claim 1 , wherein the first wake-up packet contains:
a magic bit-pattern which if received by the sleeping target system causes the sleeping target system to wake up.
3. The method of claim 2 ,
wherein the first protocol is a lower-layer protocol;
wherein the second protocol is an upper-layer protocol;
wherein the magic bit-pattern contains a bit representation of the link-layer address of the sleeping target system;
wherein the second wake-up packet is an Ethernet packet whose destination address field is set to the link-layer address of the sleeping target system, and whose payload contains the magic bit-pattern.
4. An apparatus which when located on a remote LAN (Local Area Network) which wakes up a sleeping target system located on a target LAN, wherein the sleeping target system receives packets of a first protocol, wherein the apparatus cannot use the first protocol to send a packet directly to the sleeping target system because the apparatus and the sleeping target system are on different LANs, the apparatus comprising:
a processor;
a memory which stores instructions that when executed by the processor cause the processor to create a first wake-up packet, wherein creating the first wake-up 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
a network interface configured to send the first wake-up packet to a 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 associated with the link-layer address of the sleeping target system; and
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.
5. The apparatus of claim 4 , wherein the first wake-up packet contains:
a magic bit-pattern which if received by the sleeping target system causes the sleeping target system to wake up.
6. The apparatus of claim 5 ,
wherein the first protocol is a lower-layer protocol;
wherein the second protocol is an upper-layer protocol;
wherein the magic bit-pattern contains a bit representation of the link-layer address;
wherein the second wake-up packet is an Ethernet packet whose destination address field is set to an Ethernet address of the sleeping target system, and whose payload contains the magic bit-pattern.
7. 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-up packet involves determining the network-layer address of a relay agent based on the network-layer address of the sleeping target system and a subnet mask; and
wherein the first wake-up packet contains,
a link-layer address associated with an interface of the sleeping target system which is coupled with the target LAN; and
a magic bit-pattern containing a bit-representation of the link-layer address, which if received by the sleeping target system 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 the 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
the relay agent network-layer address field which is set to the 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; and
sending the first wake-up packet to the relay agent located on the target LAN, wherein the first wake-up packet is sent using a network-layer protocol;
wherein sending the first wake-up packet to the relay agent causes the relay agent to use a link-layer protocol to send a second wake-up packet to the sleeping target system, which causes the sleeping target system to wake up.