Why PyCon 2010's Conference Wi-Fi Didn't Melt Down

jafo writes "There's been a lot of teeth gnashing going on recently about broken wireless at conferences. We just wrapped up PyCon 2010, with around 600 (out of 1,000) attendees simultaneously accessing the volunteer-run network, and response has been fairly positive. 2.4GHz (802.11b/g) continues to be problematic, but most users were on 5.2GHz (using 802.11n) and associating at 130mbps, with a 100mbps link to the net (though after the fact we found that 35mbps would have sufficed). My PyCon 2010 wrap-up reveals all the secrets of how we did it, including pretty bandwidth and user graphs."

Comments

On units and their prefixes

[Bromskloss]

Editors, please do your job before you accept a story - that's an easy way to make Slashdot much better. In this particular story, it would have been easy - no research required. As I'm sure almost everyone here knows, m != M. Also, what is wrong with "b/s" instead of "bps"? (Also, how do I write non-ASCII characters here?)

Re:On units and their prefixes

[Jurily]

(Also, how do I write non-ASCII characters here?)

What makes you think you can, huh? Just because url's can contain them and the civilized portion of the net is already fine with them?

Re:On units and their prefixes

[maxwell demon]

For some, like ä, ß, €, you can just use the HTML entities (ä, ß, €). More esoteric ones like ॐ just won't work.

Re:On units and their prefixes

[Rogerborg]

Just FYI, the "job" of a Slashdot "editor" involves scoring Rob Malda some weed when you were at community college together, writing a very small shell script to post every 25th story submission, then scarfing beer and cheetos while playing in the Furry zone of Second Life for the rest of your "career".

Mod hints: -1 Troll, +1 Informative, +1 Insightful

Re:On units and their prefixes

[TeknoHog]

What's wrong with "bps" instead of "b/s"?

"Per" is a word that does not work in all languages, whereas "/" is a universal mathematical symbol. Even non-scientists use units like km/h, at least in Europe.

Re:On units and their prefixes

[trapnest]

I suppose that would be really important if the summery were not in english.

Re:On units and their prefixes

[TeknoHog]

Where does 'b' mean byte? I have never seen that in literature, and the only times I've seen it written in conversations it can generally be attributed to laziness, often accompanied by a lack of capitalization at all.

I once filed a bug about an application that used kb/s to denote kilobytes per second. It was changed to kB/s for a while, but pretty soon reverted to the lazy form. At least they used / though :)

Here's a nice example from the manpage of tc, part of iproute2:

Bandwidths or rates can be specified in:

kbps Kilobytes per second

mbps Megabytes per second

kbit Kilobits per second

mbit Megabits per second

bps or a bare number
Bytes per second

Amounts of data can be specified in:

kb or k
Kilobytes

mb or m
Megabytes

mbit Megabits

kbit Kilobits

b or a bare number
Bytes.

Well, perhaps this is so that you can write your command line in all lowercase. In other words, laziness.

Re:On units and their prefixes

[AK Marc]

Agreed, perhaps this is only a matter of style. As a scientist I would never write something like mps for metres/second, even though the spoken unit is "metres per second". It would look silly and unprofessional, and I've already explained the point about mathematical symbols elsewhere in this thread.

In the US, mpg, mph and bps are used almost exclusively. They aren't "scientific" or "mathematical" expressions, but vernacular that took over all uses, regular, technical, and such. If you have a problem with that, it can't be fixed by what "should" be done for the scientific reasons, because if that worked, the "m" in mpg and mph wouldn't be used anyway. And it's not like a bit is an SI unit, so it's failing to fall under that standard regardless of "per" being used.

Typo in model number

[madsci1016]

The AP he used was a Netgear WNDAP350. There was a typo in the article.

I avoid conference WiFi's...

[SerpentMage]

Because of the notorious slow conference WiFi's I have learned a new trick...

I use 3G networks. Since I live in Europe it would be expensive except I get pay-per-day for the country and that averages around 4 to 5 USD per day. That is great considering I can get 3G within restaurants, in my hotel room, and where ever else... Beats having to figure things out with the Wifi...

Re:I avoid conference WiFi's...

[hitmark]

probably picks up a pay-as-you-go at the airport of whatever nation he happens to visit.

More such reports, please!

[Enleth]

Even though it's just a short report, it's going to be very valuable for anyone doing similar work, be it for a conference or for a more permanent setup. No textbook is going to protect against those "oh crap, why didn't I think of it before?" moments like some actual experience would, and this posting is the next best thing after actually having someone with experience on site. And this works for any field of applied technology, not just wireless networking.

So, thanks and be back with some more soon!

Nothing to see here, move along

[Jurily]

http://serverfault.com/questions/72767/why-is-internet-access-and-wifi-always-so-terrible-at-large-tech-conferences

Re:Nothing to see here, move along

[Incongruity]

Of course, the top answer to the question you link to comes from Sean (Jafo), the same person who authored the story submitted here. Sean's been nothing short of a hero @ PyCon for a number of years now – the one or two times we tried to replace him with a sub-contracted internet solution, it always ended painfully... or, well, more rightly, with Sean coming in and saving the day.

So, as someone who has worked with Sean on making PyCon happen, I can say, without a doubt, that he really knows how to get it done. My hat's off to him and Tummy.com

Re:Nothing to see here, move along

[Anonymous Coward]

If he's so great why did you try to replace him?

Re:Nothing to see here, move along

[AMK]

For the first year or two, Sean was an unpaid volunteer, and the wireless was an all-volunteer effort. We felt bad about using up all his conference time, so we hired a company to run the network -- they're professionals, so everything should work fine, right? -- and Sean ended up helping them diagnose problems, using up *even more* of his conference time. Now we just pay Sean.

Re:Nothing to see here, move along

[jafo]

Just to clarify, the only compensation I get for the wireless at PyCon is that my company gets our sponsorship in trade. Usually I even pay for the conference attendance and definitely the hotel and travel. This year was slightly different because the Community Service award I got last year covered the conference attendance and about a quarter of the hotel. PyCon *does* pay for the wireless APs and the like, though I do supply the router from my stash (this year: Atom 330 mini-ITX system, performed admirably).

Re:Nothing to see here, move along

[RzUpAnmsCwrds]

That wouldn't happen to be the system I sold you, would it?

IETF meetings solved this 2 years ago

[mbone]

IETF meetings are larger (1200+ typically), and basically everyone has an uses a laptop / pda, so they make for a demanding wireless environment. After some really bad experiences, resources were put into this, and the last few years, things have really improved.

What we have found is that

- it is necessary to have good gear (not all access points are created equal)
- To serve a lot of people, lower the power per access point, and put in a lot of them. Raising the power because of poor reception is a mistake.
- having both 2 GHz and 5 GHz networks really helps.
- telling attendees how to turn off "ad hoc" mode on their computers really helps.
- tracking down ill-configured boxes doing bad things on the network really helps.

Having said that, most recent IETF meeting sponsors have chosen to pay for professional wireless network providers. This is not trivial, and there is no better way to cause a flame war than to have the WLAN melt down.

Re:IETF meetings solved this 2 years ago

[mi]

IETF meetings are larger (1200+ typically), and basically everyone has an uses a laptop / pda, so they make for a demanding wireless environment. After some really bad experiences, resources were put into this [emphasis mine -mi], and the last few years, things have really improved.

At what point does it become cheaper (or comparable) to just run a CAT6 cable to every seat in the conference room? I mean, movie theaters and airplanes have that for headphones. Every laptop I've seen has an Ethernet jack... You spend some more money once, but then save on every event... And you provide better service — while emitting less radiation and consuming less electricity (would somebody think of the polar bears?!)...

Those few devices, that only have WiFi can still use wireless, but, if the bulk of your audience use cables, you can get away with cheap "SoHo" equipment...

When renovating my house, I ran CAT6 to every room — the number of power outlets is only 4 times higher, than :-)

Piffle.

[dtmos]

The bimonthly IEEE 802.11 standards meetings are co-located with other 802 wireless working groups (802.15, 16, et al.) and regularly have attendance from 600-1000 persons, substantially all of whom are active on 2.4GHz (802.11b/g) substantially all the time the meetings are in session (it's required to register session attendance, upload and download documents, etc., but is largely used for Internet-based multitasking). These networks have worked flawlessly for years. They are specially-built for the meetings by VeriLAN Event Services, a company specializing in network services for special events. Their web site claims that they have supported events with up to 5000 simultaneous users.

Re:Piffle.

[mbone]

Verilan and Swisscom are the IETF's providers at the present, for when the sponsor doesn't want to do it themselves.

When sponsors do do it themselves (generally because they sell wireless gear) I would advise them to be afraid. I still remember a poor sales-engineer from a previous meeting (that did not go well in a wireless sense) being told they had implemented some piece of the standard wrong, by engineers who had helped to write the standard. After a few rounds of that, he started visibly flinching whenever someone else came up to complain.

Hmm, other equipment options?

[Andy Dodd]

I don't like the dual-band routers much - they always seem to do a crap job serving both bands, even in the rare cases that the router supports it.

$300 each for those Netgear APs sounds ridiculous when you can get carrier-grade equipment (such as Ubiqiti Rocket series units) for far less. Instead of getting dual-band stuff, just set up independent 2.4 GHz and 5 GHz networks.

Test, you idiot

[cerberusss]

FTFA:

Crimping your own RJ45 should be avoided

Author should have said "testing should NOT be avoided".

I hate it when people say such things. A cable tester costs $15 and you neglected testing. Don't say "crimping your own RJ45 should be avoided". That's blaming someone else for your idiocy.

Re:Test, you idiot

[ZorinLynx]

As someone who crimps our own cables at work, full agreement here.

I rarely have problems with self-crimped cables. Another group that crimped its own cables here was having all sorts of problems. Why? They were doing a lousy job of it.

Test every cable. Make sure the conductor order is correct. Make sure the conductors go all the way into the connector to the stop at the end. USE THE RIGHT CRIMPER. Some cheap crimpers don't crimp all the crimp points and leave the wires less mechanically supported. The crimp point that's usually missed is the one just behind the metal contacts, which is one of the most critical points of all.

And most importantly, make sure you are using the correct plug ends for the cable you are using! Stranded and solid conductor cables require different types of plug. Using the wrong one nets you a connection that works now but won't work later.

Re:Test, you idiot

[Kizeh]

Solid is for horizontal runs (within walls), stranded is for patch cords that will be flexed, such as between a jack and a user's computer. As it's always been.

Re:i feel his pain

[v1]

Saves the worry, AND saves the fingers. Mine start cramping at about the 25th end when I'm in a hurry.

I can't believe that they seriously planned to crimp things by hand. I can understand for the occasional single long haul runs, but they made it sound like they were doing many dozens of crimps, and that's just plain silly. The money you save in not paying for molded cables you lose in time and hassle created by bad crimps.

Did you catch the other hilarious minor detail? they only had one crimping tool! That's how to turn fail into epic fail. And they PLANNED it this way... wow.

Damn toasters....

[fractalboy]

Hmmm.... that's odd.... the Cylons must have managed to just miss all of Picon's wireless access points with their barrage of nukes. Or maybe it was just part of their "plan" all along?

Re:high UIDs can't triforce

[iknowcss]

Triforce fail

Re:Learning is knowledge

[RzUpAnmsCwrds]

Actually knowing a bit about jafo and the setup at PyCon, I can tell you exactly what's wrong with your idea: money.

The IEEE/ACM SuperComputing trade show's network (SCinet) does exactly what you say. They also have 10,000 attendees, over 50 people working on the network, a decent budget, and a ton of donated gear and bandwidth.

PyCon (and jafo) don't have $100k to spend on the network. That means that you have to make do with low-cost commodity hardware. The fact that the network can stay up and deliver acceptable quality of service is a testament to jafo's experience.

Building a conference wireless network that works when you buy gear designed for that purpose isn't particularly notable.
Building a conference wireless network that fails miserably with consumer-level gear isn't particularly notable.

Building a conference wireless network that works with consumer-level gear on a shoestring budget *is* notable.