Wake on LAN - Knowledge Base
1. Wake on LAN does not boot all the machines.
Check the following:
On the Machine
- NIC should be wake on LAN complaint
- In BIOS WOL should be enabled
- Most external NIC's will have 3 PIN WOL cable which has to be connected to the motherboard.
- You can see a blinking light in the NIC even if the machine is powered off.
- Ensure that the power supply to the machine is switched ON.
On the Network
For Wake On LAN to work across subnets (or VLANs)
- Enable IP Directed broadcasts on the routers/gateways. This ensures that the WOL packets are not blocked.
- IP directed broadcasts has to be enabled in all the required routers/gateways/switches along the path. This depends on the network design.
- Alternatively, you can also add an access list in the switches to allow UDP packets from a specific machine to other subnets. For example: Access-list 101 permit udp 192.168.110.103 host 192.168.116.255 eq 5000, where
192.168.110.103 - refers to the machine generating the WOL packets
192.168.116.255 - refers to broadcast address that is being permitted
5000 - refers to the port from which the WOL packet is being sent from the generating machine.
This again needs to be enabled in all the routers/switches along the path