On Wed, May 9, 2012 at 2:43 PM, Brett Delmage <Brett [ dot ] Delmage [ at ] twobikes [ dot ] ottawa [ dot ] on [ dot ] ca> wrote: > I expect an i7 linux workstation I have could keep up with the web > requests. You are focused on the wrong problem. A netbook would likely handle the traffic you outlined. > So I'm wondering what it would take in equipment, especially wifi, for me > to set something up like this? I would NOT be able to set up any more than > one AP (or at least one AP location), given the physical limitations of > the setup, out of my control. This is the problem. The last "rule of thumb" I heard was that a single AP can handle about 20 to 25 clients (per channel) before the wireless gets saturated. It is a physics problem. I am not sure if that is active clients, or just the number of clients associated with the access point at one time. I would not be surprised if it was just the number of associated clients. There is a good bit of chatter between the AP and clients. There are only three non-overlapping channels in the 2.4GHz band. You could use three radios, on channels 1, 6, 11. Ideally with three 120 degree sector antennas pointed in different directions. That could potentially bump the number of clients up to 75. However, I am guessing that you would only get about 60 clients total as clients would bounce back and forth between access points. You could add more clients with APs running in the 5Ghz range (802.11a and some n) . There are lots of channels in the 5GHz range, but there aren't nearly as many 5Ghz devices as 2.4Ghz devices. 802.11n devices may operate in either or both bands, but many 802.11n devices are only 2.4Ghz. You don't need a dedicated AP. Alfa makes or made usb WIFI devices that are supported under Hostapd and Linux. You server could be the AP as many radios and you want. Another option is to run the AP in one corner and tell your participants that if they want access to go to that area. You may want to turn down the transmit power to limit the range and number of connected clients. Also don't forget to use WPA2. It sounds wrong, but even if everyone knows the WPA passphrase it is "hard" to sniff another clients traffic as there is a separate encryption key per client. There is a single group key for broadcasts, but broadcast information isn't that interesting. There is an attack, but IIRC it only works against WPA2 in enterprise (radius + x509 cert) mode, and it is fairly hard to pull off. Of course there is always the potential for a man-in-the-middle attack with a rogue AP but that is always a problem with WiFi. -- sg