[Server-devel] [laptop.org #8321] Questions about XO mesh networking

[Michail Bletsas]

Bryan Berry <bryan.berry at gmail.com> wrote on 03/28/2008 12:55:28 AM:

> I am cc'ing Martin Langhoff, John Watlington who are in charge of the
> School Server at OLPC
> 
> > 1.  ideally the school server (running XS) will have 3 active antenna
> > each running on a diff channel (1,3,6) and XOs will connect to one of
> > these.
> 
It will have three 3 active antennas running on the three non-overlapping 
WiFi channels which are 1,6 and 11
These active antennas will be configured as Access Points in dense 
deployment scenarios.


> >2. Or should we replace the WRT54G with
> > another AP/Router in the short term?
> 
> I would replace the WRT54G. I hate them. I have had 3 fail on me in the
> last year. I would get 3 other wireless routers. I like DLink
WRT54G's are prefrectly fine devices when used in the context that they 
were designed for (home gateways).
I wouldn't use them in schools that will require more than 1 (because of 
the way they spport lazyWDS with the stock firmware) and if they have to 
be used, I would load them with some openWRT firmware variant (so that 
lazyWDS can be partially controlled)

For a school with 200 laptops, one low-cost solution that doesn't involve 
too much tinkering with device firmware is the DWL2100AP from Dlink. In 
general one has to always keep in mind that the less a device has to do, 
there is more probability that it would do it without many bugs.


> 
> 
> My understanding is that in a dense deployment such as yours you should
> use a regular wireless router and not the active antennas, for the short
> and the long term. Wad and Michailis, pls correct me if I am wrong.
The correct wording is to use access points. The cheapest way to get an 
access point is to use a WiFi router with the routing functionality 
disabled. (Relatively easy to do on most of them, connect everything on 
the LAN ports after making sure that the internal DHCP server is 
disabled).


> 
> >3. Running ejabberd on a central server means that collaboration
> > features will work while the XOs are connected to an AP (or school
> > server with active antenna)? The only change we need to make on the 
XOs
> > is to support this, is to change the jabber server using
> > sugar-control-panel?
> 
> Correct
> 
> >4. Can we expect to get around 50 XOs per channel?
> 
> 
> Don't know, sounds good to me. We are planning 60 XO's per channel 
> w/ a Deliberant Radio + Omni 12 dbi antenna
> (Dev can provide more details)
> 
> Wad, Michailis can you advise?
Yes (with an Access point currently)

M