Still very much a thing in the world of optical networking ("rolling the cable", i.e. switching the two sides at one end to match tx/rx up correctly, is a common first step in debugging a link that won't come up -- standard fiber patch cables are effectively crossover cables but when you're running through patch panels, have multiple cables in the path, etc it can end up mismatched). Some plants have primarily switched to bidirectional (bidi) transceivers that transmit and receive on two different wavelengths on the same strand, but that also requires matching optics at the other end with the tx/rx frequencies reversed.
"high-voltage custom power supply that converts 120V/240V AC line voltage to 330V DC power for the motor and 3.3V/5V/12V DC for the communications board"
When I read that, my brain flipped thinking surely that has to be a typo. Then, "he motor is seemingly custom to account for the exceptionally high rated power (stalls at 5A at 330V DC, which is hard to believe, possibly even a misprint on the motor casing)"
So if it's a misprint on the motor, they designed a power supply for something totally unnecessary. Otherwise, if it's not a misprint, that's one helluva motor
The issue has been identified as a DNSSEC signing problem at DENIC, the organization responsible for the .DE top-level domain. Cloudflare has temporarily disabled DNSSEC validation on 1.1.1.1 resolver in order to allow .DE names to continue to resolve. DNSSEC validation will be re-enabled when the signing problems at DENIC are known to have been resolved.
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(and in case it changes again, now it says)
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The issue has been identified as a DNSSEC signing problem at DENIC, the organization responsible for the .DE top-level domain. Cloudflare has temporarily disabled DNSSEC validation for .de domains on 1.1.1.1 resolver (as per RFC 7646) in order to allow .DE names to continue to resolve. DNSSEC validation will be re-enabled when the signing problems at DENIC are known to have been resolved.
That's more useful. A big question is how much is really turned off in a computer waiting for the wake-up packet.
"The power to the Ethernet controller must be maintained at all times, allowing the Ethernet controller to scan all incoming packets for the Magic Packet frame". So the full network controller is still alive. There's not some tiny Magic Packet detector hardware running off a rechargable coin cell or something, with the main power supply turned off. At least not in the original design.
A lot of sleep modes leave more running than you'd expect.
The Ethernet cards that wait for WoL packets use the "+5 V Standby" supply voltage, which is available on the PCIe slots, coming from the ATX power supplies.
"+5 V Standby" is provided by a separate voltage regulator, which continues to work even when the PC, including the rest of the ATX PSU, is shut down.
"+5 V Standby" typically can provide up to 2 A, i.e. up to 10 watt, though some old PSUs may be able to deliver only up to 5 watt and some of the bigger ATX PSUs may be able to deliver up to 15 watt.
Besides supplying the Ethernet cards, to enable WoL, "+5 V Standby" can be used by the USB ports if configured so in BIOS, to enable waking the PC with the keyboard, or to enable charging from USB even when the PC is shut down.
> In this script a fifo is created where the output of tcpdump is dumped. For whatever reason tcpdum | grep was not working properly, and would have a “miss” rate of about 50%. So tcpdump output is dumped in the fifo:
>
> tcpdump -i eth1 2>&1 | tee > /tmp/tcp_wol.fifo &
>
> and it’s grepped in a loop, when the magic packet (see http://en.wikipedia.org/wiki/Wake-on-LAN) is found , a led is triggered, thus powering-up the computer (with a driver and relay, will come back at this).
I have measured the powered off energy usage of my desktop computer at the wall, and it hovered about 5-6 W (resolution of the power meter was just whole watts). That would be split between losses in the PSU and WoL, and possibly other circuits. But I don't have any other such wakeups enabled (but that doesn't mean that the motherboard is designed super well to disable it fully if not needed). Turning off WoL made a difference of about 2 W (meter hovered around 3-4 W).
One thing I noticed is that if I connect to a gigabit upstream port, that the connection drops to 100 mbit/s when the computer is off, but if I connect to a 2.5 Gbit port, it stays at full speed. This is based both on LEDs on the connector as well as the OpenWRT dashboard on the router. If it made a difference it was too small to reliably measure with my simple meter.
If it makes a difference (potentially does for conversion losses I would guess), this is on 230 V mains.
I was distracted by the poor typesetting in parts of the page. The meaning of the text is overwhelmed by the distracting spacing used to justify the text:
> . I n o t h e r w o r d s , s i l i c o n - o r g a t e - l evel
And they collaborate with Headscale to provide an open-source coordination server (with, unsurprisingly, a more limited featureset, but it works fine with their closed-source GUI client): https://tailscale.com/opensource#encouraging-headscale
I use the combination myself and it works quite well, but of course is less convenient than using their product (which I also do in a different context). Overall I'm pretty happy with their open-source stance.
I've been thinking about that illustration of Smaug for nearly 40 years and I never knew where it came from (I didn't recall it was from a Tolkien-related thing, but I remember it vividly otherwise)! I must have seen it at a friend's or the library since as far as I know we never had these at home.
> [The power] light informs the user that the X41 is on—no, really. There should be an ontological indicator next to it to let the user know the computer really exists.
The ratio of the length of the diagonal of a pentagon to one of its sides is the golden ratio -- easiest visualization is with similar triangles. Draw a regular pentagon (sides of length 1 for simplicity) and pick a side, make an isosceles triangle with that side as the base and two diagonals meeting at the opposite point. Go one side length down from the opposite point and mark that (F below). Convince yourself that triangle DCF is similar to CAD (symmetry gets you there).
Now we wish to find the length of, say, CA. From similarity CD/CA = FC/DF, and CD = DF = 1, and CA - FC = 1, so the ratio simplifies to... CA^2 - CA - 1 = 0 which yields the golden ratio.
A
.'.
.' | `.
.' | | `.
B.' | | `.E
\ F| | /
\ | | /
\ | | /
\|_____|/
C D
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