When there's only one

...there's only one choice
Everything here is my opinion. I do not speak for your employer.
November 2013
January 2014

2013-12-01 »

"What unfortunately happens is we have about… 350 million interactions with consumers a year, between phone calls and truck calls. It may be over 400 million, and that doesn't count any online interactions which are over, I think, a billion. You get one-tenth of one-percent bad experience, that's a lot of people — unacceptable." – Comcast

Hmm, I have a feeling that more than 0.1% of Comcast customers have had a bad experience with them.  If they start from the assumption that their customer satisfaction is 99.9%, they will probably not succeed at fixing the problem.

Makes a good sound bite though.

2013-12-02 »

"Please update to the latest version of our proprietary driver so we can resume certifying your device."

"Okay, I didn't realize we were behind.  Which driver version is best?"

"The version coming out next week."

2013-12-03 »

Wow, I can't believe how evil I am.

I should write device drivers every day.

2013-12-07 »

Fixed some stuff.  Broke some stuff.  Unclear about ratio.

2013-12-08 »

"Hamming once asked me, 'What progress of today will be remembered 1000 years from now? Will your work be remembered 100 years from today?'" – Leonard Kleinrock, 2007

Tough questions.

2013-12-13 »

Oh good.  One more reason not to try to use 40 MHz wide channels on 2.4 GHz wifi: there is no way to do the "1, 6, and 11" trick to prevent partially overlapping channels.  40 MHz mode basically uses two adjacent 20 MHz bands, which means the two channels you eat are exactly 4 channel numbers away from each other:  But anybody using a channel less chan 4 channel numbers away from you will be partially overlapping with you, which is a worst-case scenario for wifi.


If you put 40 MHz activity on channel 1, it also uses channel 5, which interferes with channel 6.  If you use channel 6, it also uses 10 or 2, which interfere with 11 or 1, respectively.  If you use channel 11, it also uses 7, which interferes with 6.

It would be possible to have on 40 MHz channel and one 20 MHz channel in the band (1+5 and 11, for example) if we all agreed to do that.  But of course we didn't all agree to do that.

That said, it explains the strange popularity of channel 5.  It's okay for some people to use channel 1+5 and some to use channel 5; they are still competing for the same channel 5, but in a way that wifi CSMACD is designed to deal with.

So it would appear that 1, 5, and 11 is a better choice than 1, 6, and 11.

Of course there's one more complication: 802.11b carriers apparently take 22 MHz of bandwidth instead of the 20 MHz used by 802.11g and above.  Thus, channels 1 and 5 overlap slightly if you're using 802.11b.  Luckily, nowadays basically nobody is (or if they are, it's because they're super far away from their nearest AP, so probably the extra 2 MHz overlap will have especially low power and not interfere much.)

2013-12-19 »

Note to self:

When you have two back-to-back half-hour meetings called "Meet for coffee," do not actually take that literally.

Also, when barista sees you for the second time in half an hour and you ask to please refill your cup rather than waste a new one, and she asks, "do you maybe want a double this time?" the correct answer is "no."


2013-12-20 »

"I think that 1 and 2 are fine.  I'll ask about 3, mostly to see the expression on their faces after I ask.  I'd imagine that this is fine. "  – lawyer

2013-12-24 »

I'm thinking about pure-wifi repeaters lately.  I came home for Christmas and my dad had gotten himself one of these:


It's pretty neat.  $45 and it has a battery and a special "wifi hotspot" mode, specially designed (supposedly) to deal with wifi hotspots that need stupid login pages.  The idea is you can use it in a hotel room and all your devices and share a single link to hotel wifi.

Now okay, I haven't validated the hotspot feature (they don't have a stupid login pages at my parents' place) and their UI is pretty awful and buggy.  But I like the idea and I like the price.  And it really does boost wifi signal strength when used appropriately.

Mind you they only have a 4 Mbit/sec Internet link here.  Repeaters use your wifi bandwidth pretty inefficiently, but you have a long way to go before 150 or 300 Mbit/sec gets all the way down to 4.

2013-12-30 »

At last, people admitting that there's an actual reason people don't want to switch to your thing when you make it unnecessarily incompatible with the old thing and don't solve any important problems.


Next stop: IPv6.

(Okay, only sorta kidding with that analogy.  I actually kind of thought python 3 might catch on eventually... :))

November 2013
January 2014

I'm CEO at Tailscale, where we make network problems disappear.

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apenwarr on gmail.com