Sharing User Experiences with OLPC XO Wifi Connectivity - Glew 2007 Jan

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From Sharing User Experiences with OLPC XO Wifi Connectivity and Wifi Connectivity.


Brief

Situation: setting up two G1G1 OLPC XOs, connecting to home net.

Background:

  • who am I: Andy Glew
  • wifi: Comcast Linksys WCG200-CC - combined cable modem / wifi (a/g)
  • network status: home net had been stable for a year or more, with 2-4 laptops connecting, and occasional wired use.

Status: connected, with WEP 128.

  • Possible magic trick required: padding passphrase
  • Annoyance: constantly need to reenter WEP passphrase


Log

Started trying to connect OLPC XO circa 10am. Although the network appeard on the XO's neighbourhood view, connections failed.

Eventually resorted to my BKM (Best Known Method) for this Linksys/Comcast box: I reset it. Of course, that meant I had to ensure that all existing devices continued to work... (Actually, even more fun: I made the mistake of resetting the router while connected to the Internet. I was hacked before I managed to reset all of my security settings, so had to physically disconnect and start again.)

After the reset, the XOs saw my Wifi network, but connections failed. As before.

Tried various channels, WEP 64 and 128 bit. No joy.

There seems to be quite a long delay between reconfiguring Wifi and the XO discovering the new network. E.g. I was changing channels, WEP 64 and 128, and, for good measure, SSID. The XO did not observe the new SSID for circa 20 minutes after the Wintel laptop sitting next to it had. In fact, I ended up creating a BKM for the XO: to get it to observe a new network, power cycle (press the power button for 10 seconds to force it to power down, then power up). Even power cycling did not always work.

  • Q: is there an XO command to force to rescan? The equivalent of Windoze "repair"?

14h30: disabled security - no WEP. *Now* the XOs connect.

  • actually, to be a bit more precise: after waiting circa 15 minutes, at each XO separately (circa 45 minutes elapsed), I was able to get the XOs to connect - i.e. I was able to see the white ring in the neighborhood view
  • possible magic: before I was able to connect to my wifi, I had to wait while the XO connected to each of the 3 mesh access points in my neighborhood, and then disconnect those. It looks like the XO tried the meshes first, and did not try to Wifi until forced to.

Now, trying to re-enable WEP...

15h27: WEP 128 seems to work.

Possible magic trick - i.e. something I ended up doing, that may have been necessary, or which may have just been thrashing:

  • at first, and once again, I was unable to get WEP security working - trying several channels, 64, 128, hex / passphrase / ...
  • eventually I tried padding out the 128 bit WEP passphrase to the maximum number of characters that the Linksys box permitted - 31.
    • when I entered that passphrase in to the XO, seemed to work. If I used a shorter passphrase, it dod not work.
    • conjecture: padding characters not treated uniformly?
    • strangeness: while 31 characters is a "special" number, it doesn't correspond to what I understood to be the appropriate lengths.

Unfortunately - while I have been able to get the XOs connecting to the internet, and even to this OLPC wiki, they are slow. I was hoping that I could be able to say "I edited this wiki page using my XO". ... Actually, now I am doing so. But, viewing a page such as this page on this wiki seems to take circa 45 seconds on my XO. versus <5 on the laptop next to it.

Acceptable given the price and other differences. But, it may be worth warning people that "Your XO may not be hung; it may just be slow."

Further Notes

I seem to be required to reenter the WEP passphrase (31 characters) every time the XO powers up. This is becoming annoying. Surely there is some way to automate? (Also, I would prefer the password to be hidden, as pitiful as that might be, because otherwise I will need to tell my 8 year old daughter what the password is - which amounts to telling the whole neighborhood).

Now for the real test: letting my 8 year old daughter and her friends use the XO.

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