Thoughts on conferences

Exactly, it's amazing how many people do exactly that :-), but at the time you are chilling in the lobby it's usually not a problem, the peak problem actually happens during the keynote and the most packed sessions. When you get several hundred people in a room, each of which are carrying multiple wifi devices that they all set to update, then you really have headaches (why the people battle to get into the room and then do this rather than doing it in other, less crowded areas is a very interesting point to think about)

This is why last year we ran a local repository for Debian and Ubuntu. We tried to do so for Fedora, but they are not setup in a way that lets us do so.

There are some pointers in the answers to this serverfault question: http://serverfault.com/questions/72767/why-is-internet-ac...

The posts from the pycon network admin provide a lot of good info.

But there are a handful of core issues to think about.

First, if the radio portion doesn't work, nothing else has a chance.

The gut reaction of many people is to turn the transmit power up, which is exactly the wrong thing to do.

Think of people at a party, turning the power up is just everyone talking louder, which just causes more interference. Instead you want to turn the power _down_, ideally to the point where the APs are transmitting at the same effective power levels as the devices connecting to them (after all, it does no good for the AP to be able to broadcast farther than the thing you are trying to talk to as you won't hear the response), since the APs tend to have better antennas, this can be lower in terms of watts out than what the client devices are doing.

Second, don't put too many radios in a given area.

This is tricky as not having enough radios leads to gaps in coverage, but having too many leads to interference problems. Especially on 2.4GHz there are only three usable channels. On 5GHz you have many more channels, so you can put far more APs in a given area without any problems.

Do some testing of the building you are setting up in. some walls are going to be transparent to the signals, others will block the signal. Use this to your advantage to allow you to have more APs in an area without them being able to hear each other (and the people's devices in the other rooms)

As for Directional Antennas.

The first thing to realize is that all APs are directional to some extent, some very significantly so (the 5GHz only netgear APs I've used for the last two years had a significantly stronger signal out the back of the AP for example)

The second thing is that directional antennas help both receiving and transmitting (unlike turning up power which only helps transmitting)

The third thing is to realize that the area of the antenna pattern where it receives poorly can be more important than the area where you get better reception.

The fourth thing to realize is that it doesn't matter if the antenna is hyper-directional and so can't hear another AP (or people sitting in an area) if the clients that you are talking to can hear those people (in radio terms this is called a hidden transmitter)

This being said, directional antennas can help you. they can let you position the APs where there is power and network rather than where you really want them.

If you have a L-shaped layout of rooms, you may be able to position the APs at the corner of the L to cover both legs.

If you have a large room (a long theater layout for example), you can put one AP at the front and one at the back with directional antennas to cover the entire room well.

Once you have the RF portion in some semblance of sanity, then the digital aspects start to come in to play. check how many clients the AP will support, some of them will only allow a small number to connect (I have some expensive 'commercial grade' APs that only allow 32 users to connect for example)

Run the same SSID on all the access points on a given band so that movement between them is transparent. I opt to run a different SSID for the 2.4 and 5GHz bands, although I see claims from commercial vendors that they have technology to 'steer' clients that can use 5GHz to that band, I don't understand how it can work (any pointers would be appreciated)

Watch your Internet Bandwidth. It's frequently hard to have enough. I will have 45Mb at SCALE, and I wish I had 2-3x as much (although it's _so_ much better than the 4.5Mb I had two years ago at the old hotel)

I've got mixed thoughts on QoS, it sounds like it should be a good idea, but there are a few problems.

First, you really need the QoS on the downstream side from your ISP, doing anything from your side is working very indirectly.

Secondly, it's a significant amount of overhead on your systems.

also, look carefully at the bufferbloat info for tweaks to amke

I need to do some diagrams to give examples of this stuff.