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[school-discuss] Re: Wireless network ambulance for classrooms w/o wired network connectivity

on Thu, Jun 09, 2005 at 11:19:32PM +0200, Damiano Verzulli (damiano@xxxxxxxxxxx) wrote:
> Daniel Howard wrote:
> >[...] convert our elementary school's network to support 
> >LTSP/thin clients, one of the challenges we have is that due to 
> >construction 
> >[....]
> Please note that, while driving along the way of the LTSP/thin_client 
> adoption, another challenge you might face with, expecially employing 
> wireless-lans, it's the bandwidth!
> As the standard LTSP rely on the X protocol and the X protocol consumes 
> lot of bandwidth, I think that with a 11Mbps links you could experience 
> some problems!

My experience with ~9 clients on a 802.11b WiFi net, I found performance
for X was tolerable for basic work, though noticably laggy for graphics
(e.g.:  GIMP).  This with contention from web and file/print access over
the same segment.

For those comparing wired 10MB/s links, remember that WiFi is the
equivalent of hubbed, not switched, networks.  And that there's the
security concern of a sniffable link.
> In order to avoid such problems and, also, in order to "improve" (a bit) 
> the overall quality of the whole architecture, you should take a look at 
> NX technologies (www.nomachine.com). It should be added to LTSP quite 
> easily. Please note that the "core" of the NX architecture is 
> _open_source_ and, as such, can be used freely. There're also a FreeNX 
> project, somewhere on the web, that should embed all (and only) the 
> open-source components of NX (but I can be wrong. Please check!).
> Please note that NX let user to access a central server via a graphical 
> interface also with a standard 28.8 kbps modem. Something simply 
> impossibile with standard X protocols.

Actually, not entirely, though it's pretty darned slow.  Using lbxproxy
helps, as well as a very low overhead windowmanager, minimual updating
of screen (that means, e.g.:  few performance meters -- most of the
WindowMaker dock apps update ~10x/s), and simple graphics (solid
backgrounds, non-gradient titlebars).


Karsten M. Self <kmself@xxxxxxxxxxxxx>        http://kmself.home.netcom.com/
 What Part of "Gestalt" don't you understand?
    One should remember that the Universe is large enough that unlikely
    things happen really quite often.

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