[OT] Wake on LAN

[Dave Liquorice]

Anyone kicked a windows box into consistently waking up when sent a Wake on LAN "Magic Packet"?

Windows Vista Home Premium, will wake up some times when the packet is sent and the NAS always wakes up when sent it's packet from the same program so confidence is high that the correct packet is being sent and that the BIOS settings are right.

In typical WIndows fashion there are half a dozen or more settings scattered across about three dialogues, all in different bits of the UI. Some settings appear to interact.

Been fiddling and now the machine doesn't wake at all. It would wake from "sleep" if you put it to "sleep" waited for a few seconds after the power down the sent the Magic Packet. But if you left it "asleep" for a period of time (FSVO: "period") it doesn't wake up.

Has anyone got a consistently working set of WOL settings for 'doze?

[Jethro_uk]

I have a vague memory that some routers can strangle the packets - WOL has always been iffy over the internet.

Slightly OT, but it was only a week ago, I learned you could get Telnet enabled power switches, which were used for remote restarts in the 80s and 90s ....

[Dave Liquorice]

'doze?

This isn't across the internet it is within the same LAN subnet. The only device between the Magic Packet sender and the target machine is a non-managed gigabit ethernet switch.

[Jethro_uk]

Fairy nuff ...

That said, I did mess around with WOL a few years back. This would be under XP. It worked "perfectly". However, I then caught the machine sneaking itself on when no magic packet had been sent.

Like most things that could be *very* useful in the tech world*, I can't help feeling the whole thing is half-heartedly half-baked.

*Bluetooth integration is another one.

[Michael Chare]

I thought Wake On Lan was a feature of the hardware bios rather than the OS.

[Lee]

The lan port on my desktop machine stays powered all the time (even in S5), it will reliably WoL if it's in hibernate (S4), trouble is other things seem to wake it up as well...

"Sleep" on the other hand seems somewhat problematic on this particular motherboard (lots of forum posts), so I have that disabled :)

[Dave Liquorice]

IMHO that's how it should be, send the packet, hardware recognises it and instructs the PSU to power up, ie the same as pressing the power switch to turn the PC on. What happens after that isn't relvant the PC is on and should boot, wake up, come out of hibernation or WHY.

Windows has other ideas and must some how get between the LAN hardware and the PSU hardware.

In theory, seen in many places on t'net, Windows won't come out of hibernation (be that real hibernation or hybrid hibernation) only sleep.

The LAN hardware can probably be configured to respond not only to the really rather carefully constructed Magic Packet and/or some other packets that are musch more likely to occur in normal traffic. The LAN port on my target machine is configured for Magic Packet only. Or was I wouldn't be surpised if windows has tweaked it to some other setting.

[Andy Burns]

Yes, The actual waking up is done by the ethernet hardware (when configured in the BIOS), but the O/S or an app generally has to "prime" the WoL ready to be woken as it shuts down, I've not really fiddled with waking windows PCs, more Linux PCs ...

[Andy Burns]

Just looked on this Win10 netbook,

under Device Manager, Network Adapters

the properties of both the WiFi and Giagabit NICs have on the Power Management tab a setting for "Only allow a magic packet to wake ...", that is a sub-setting which can be enabled if "Allow this device to wake..." and "Allow the computer to turn off this device..." are both ticked.

[Lee]

Yes it's nice hibernation works as intended on this board, shame sleep dosen't work as well as it should... though hibernation is pretty quick with an SSD anyway so it's not really an issue.

One thing that was annoyingly (and clearly by design) waking it, was a DLNA app on my iPad, which just seems to try to power on anything it sees (or has seen previously)...

[Lee]

Tisn't a "green" switch is it? Some combinations seem to do weird (but probably intended) things - my desktop PC is now plugged into the router, but when it was plugged into the switch* the link used to drop to 10mbps if the PC was in "hibernate" and it sometimes took a second (or more) tries to "wake up". The NAS is still plugged into the switch, but that wakes up instantly...probably becuase it dosen't have a "green" lan :)

*8 port gigabit "green" thing, don't remember the previous "non green" one doing it.

[Tim Streater]

What's the difference between hibernation and sleep ?

[Richard]

[Tim Streater]

OK, ta.

On our Macs here, there's essentially no difference between power-off and hibernation, but functionally it's the same as what Win provides.

[charles]

in biological terms, hibernation is a deep sleep which last a long time.

[Richard]

I don't usually bother shutting down my laptop (just checks settings.. ) have it set to sleep when the lid closes. The wife's macbook which also runs Win7 in Parallels is used in the same way - no idea what the settings are there.

[Santo Brown]

Hibernation writes the ram to the drive and reloads it back into ram when it comes out of hibernation.

[dennis]

On win 7+ there is also hybrid sleep..

it makes a hibernation file but just sleeps to allow a fast restart but doesn't lose anything if the power goes.

[Andrew Gabriel]

The OS has to leave the NIC in a state where WoL can work, and an OS (or rather a driver) which doesn't know about WoL may well leave the card in a state where WoL won't work.

If you multi-boot different OS's, this can be a particular problem.

Also, some cards will run their own ARP when the system is powered down so the WoL packet can be routed to an IP address (usually over UDP) rather than using the raw ethernet address (which is not routable across networks). This adds another whole layer to go wrong, particularly in DHCP environments.

[Adrian Caspersz]

Not so much strangle, but lose....

For reliable WoL you might need to add an static entry (mapping MAC to IP address) in the routers ARP table. Getting to that depends on how locked down these settings are, or hidden in CLI.

e.g. Wake on LAN From Internet Using a Thomson Router

What otherwise happens is the computer powers off, the dynamic ARP entry normally created on a lease is lost and then nothing wakes.