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Q: Pattern-match wake-up in wake-on-LAN NIC ( No Answer,   3 Comments )
Subject: Pattern-match wake-up in wake-on-LAN NIC
Category: Computers
Asked by: wakeupguy-ga
List Price: $10.00
Posted: 05 Dec 2004 20:29 PST
Expires: 04 Jan 2005 20:29 PST
Question ID: 438617
How is pattern-match based wake-up where the PC is woken-up when a
certain byte pattern is seen in a network packet implemented in a
wake-on-LAN capable network interface controller? I am not asking
about Magic Packet or directed packet wake-up. Specifically, how is
this byte pattern sent to the controller and how does it match this
pattern against the received packets to generate the wake-up signal to
the PC?
There is no answer at this time.

Subject: Re: Pattern-match wake-up in wake-on-LAN NIC
From: telxon-ga on 08 Dec 2004 06:18 PST
The "pattern" on the receiving end (the NIC) is pre-set to recognize
the pattern and begin the wake-up process. That's why some NIc's are
Wake-On-LAN(WOL) and some are not. The actual wakeup process begins
after the receipt of the pattern, an interrupt is sent to the
mainboard, which powers-up and begins whatever the boot process is
defined as in the BIOS.

Subject: Re: Pattern-match wake-up in wake-on-LAN NIC
From: doomwolf-ga on 08 Dec 2004 09:17 PST
Wake-on-LAN (WOL) is a mid-1990s industry standard that makes it
possible for an Ethernet adapter to wake-up a sleeping computer using
a specially-defined WOL packet.

The WOL packet is a standard Ethernet packet with the MAC address of
the target computer repeated sixteen times in the data field. For
example, if the Ethernet address of a target computer is
01:02:03:04:05:06 (6 bytes), then the LAN controller of that machine
should be looking for the following sequence inside the frame:


Knowledge of MAC addresses beyond a subnet is virtually impossible.
Thus, sending a WOL packet across multiple subnets - that is, routing
a WOL packet - is not feasible. The WOL packet is also not part of the
existing standard TCP connection establishment packet sequence.

After receiving the packet, the NIC sends a signal to the motherboard
through a Wake-On-LAN cable terminated by a 3-pin connector on each
side. That signal starts the standard booting procedures of the
motherboard BIOS as if you had pressed the power on button.

The motherboard must contain a complementary metal-oxide semiconductor
(CMOS) that is designed to use Wake on LAN technology for this to
Subject: Re: Pattern-match wake-up in wake-on-LAN NIC
From: wakeupguy-ga on 10 Dec 2004 09:55 PST
Yes, I am familiar with the Wake-On-LAN specification. However, I am
asking about the newer ACPI compatible pattern matched wake-up where
the NIC can be programmed to wake-up on a specific pattern of bytes in
a packet, for example the PC?s hostname. How can the NIC be programmed
to wake-up on a particular sequence and how does the NIC match the
packet data against the pattern?

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