greetings everyone,

i was wondering if anyone who's had a bit of experience with the etherwake program or something similar can answer this simple query for me:

can Wake-on-LAN (WOL) 'magic packets' be effective when sent over a network switch?


elaboration:

i have a debian sarge machine (A) running as one node of a simple home network. the etherwake package is installed on this machine, and used to send a WOL packet to another machine (B) on the same network, passing through a simple 5-port switch.

machine B has Wake-on-LAN enabled and is 'soft-powered-up' (i.e. one can see a light on the motherboard). when A sends a WOL packet to B's hardware ethernet address, no errors are reported. however, B never 'wakes'. if my recollection is correct, when the two machines were connected directly (port to port, without a switch) in the past, B would 'wake up' instantly -- unfortunately this setup cannot be replicated anymore.

any ideas?

Make sure you are sending the WOL packet to the network broadcast address rather than the specific machines IP address. ex: 192.168.1.255 instaid of 192.168.1.2. When you send a WOL packet from machine A, it issues an ARP request to find the MAC address of the host it will send te packet to. Since the destination machine is not on to respond to the ARP request, machine A will not know what destination MAC address to include in the header of the IP packet. By using the network broadcast address, the packet will be broadcast to the destination network with a broadcast MAC address. Therefore all machines on the network will see it, however, only the machine who sees its own MAC address in the packet will act on it (wake up).

Hope this helps