wake on lan

[madfish]

OK, all my nic have this and all my mobo's support this, just wth is it and should I have it enabled?
I have an idear thats it's for waking up machine via th lan. other then that I'm lost

[Mntsnow]

Thats correct. It makes it so you can remotely boot the machine via the Network.

[madfish]

soo should I enable this? { another geek thing to fool with :D } it's not like I have to walk very far. would this be a good thing to know/learn about?

[Mntsnow]

If you dont mind your systems getting booted due to traffic on your network then feel free to. I prefer not to use it :)

[madfish]

Never mind , the brat does enough of that himself

[edwelly]

good question madfish - I always wondered the same thing...
when would you want to do use the WAKE feature?

[Mntsnow]

Remote locations where there usually isnt a person around to push a button after a power outage :D

[edwelly]

I see - thanks!

[DVNT1]

Originally posted by Mntsnow
If you dont mind your systems getting booted due to traffic on your network then feel free to. I prefer not to use it :) This could be misleading because WOL doesn't allow just any network traffic start up the computer. It takes a special data packet.

I use it to start all the user's computers 30 minutes before they come in to work. This saves the startup time, allows time for network software installations, and still keeps electric costs lower than running the computers 24/7.

[Mntsnow]

Thats true Dvnt...I should have been more clear on that. Thanks for clearing the air :)

[madfish]

"It takes a special data packet"

and what is this packet?

[DVNT1]

Once the LAN controller has been put into the Magic Packet mode, it scans all incoming frames addressed to the node for a specific data sequence, which indicates to the controller that this is a Magic Packet frame. A Magic Packet frame must also meet the basic requirements for the LAN technology chosen, such as SOURCE ADDRESS, DESTINATION ADDRESS (which may be the receiving station's IEEE address or a MULTICAST address which includes the BROADCAST address), and CRC. The specific sequence consists of 16 duplications of the IEEE address of this node, with no breaks or interruptions. This sequence can be located anywhere within the packet, but must be preceded by a synchronization stream. The synchronization stream allows the scanning state machine to be much simpler. The synchronization stream is defined as 6 bytes of FFh. The device will also accept a BROADCAST frame, as long as the 16 duplications of the IEEE address match the address of the machine to be awakened. If the IEEE address for a particular node on the network was 11h 22h 33h 44h 55h 66h, then the LAN controller would be scanning for the data sequence (assuming an Ethernet Frame):
DESTINATION SOURCE MISC. FF FF FF FF FF FF 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 11 22 33 44 55 66 MISC. CRC.

There are no other restrictions on a Magic Packet frame. For instance, the sequence could be in a TCP/IP packet, an IPX packet, etc. The frame may be bridged or routed across the network, without affecting its ability to wake up a node at the destination of the frame.

If the LAN controller scans a frame and does not find the specific sequence shown above, it discards the frame and takes no further action. If the controller detects the data sequence, however, then it alerts the PC's power management circuitry to wake up the system.


Another resource is... http://www.networking.ibm.com/eji/ejiwake.html

[Mntsnow]

Well it looks like DVNT1 is already at work :)

[Axel]

guys - the only real reason to have wake-on-lan enabled, as far as my experience takes me - is if you had a remote unmanned location you needed to reboot on occasion , or if you are doing electronic software migrations during the late evening hours and haven't had success in training the bone-heads in the field to leave their CPU's on all the time to accept software upgrades.....

but chances are, if you had a critical app on a PC that died due to a power outage and you hadn't taken extreme care setting up the system so it was extremely hang resistant - wake on lan would be worthless to you 2/3rds of the time anyway.....

Also - it's totally amazing to me how many end users leave floppies in their PC's and then turn the damned thing off - you try to do WOL and never get anywhere as the screen displays "invalid system disk" to an empty chair.....

For the home and most small office users - WOL is nothing more than a security breach waiting to happen as any random pings out there hit your box - and on the WWW this happens several times an hour on most PC's..... - My home units don't have WOL enabled - it's a waste of juice and bad for security.

and that's the benefit of my WOL experiences so far -