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Re: How bandwidth requirement could be reduced when using thin clients?



On ons, 2004-10-06 at 10:55, Gavin McCullagh wrote:
> Hi,
> 
> On Wed, 06 Oct 2004, Ben Higginbottom wrote:
> 
> > >It's also a requirement to tackle 2-8 Mbps bandwidth between the schools 
> > >and a central server-farm. In my experience an university often has at 
> > >least 10 or 100 Mbps between buildings. It's not posible to increase 
> > >the bandwidth to 10 or 100 Mbps in the near future. 
> > 
> > IIRC When I tried to break Owens test room, it was 30 machines on 10Mb's 
> > and they all handled opening open office at the same time without 
> > difficulty. I can provide you with Owens email if its not on the 
> > presentation and your interested in harder numbers.
> 
> When you say OpenOffice (OOo) on 30 machines, what were you testing?  I may
> be wrong but I would guess that OOo running on 30 or more clients, be they
> thin or otherwise wouldn't likely cause that much bandwidth usage.
> 
> If all clients started up OOo exactly simultaneously over nfs/afs, that
> might be a different story as the binary itself is a big file(s).  If
> anything though, this might reveal a slightly improbable situation where
> thin clients are more bandwidth economic than their nfs/afs counterpart.
> 
> I realise OOo would load the server, but Knut's purely talking about
> bandwidth.

We've done a similar here at FAIR.

Fifteen to twenty people hammering all we could at thirtyeight
thinclients with openoffice.org. No noticable slowdowns with a 1Gbyte,
1,5 Ghz uniprocessor machine.
At least eight of them were connected to a 10Mbit hub. 

Short story? No demand for video; no problem.
The "sleep state" for a thin client doesn't require much, compare it to
the bandwith demands of ping. The client can't get totally unresponsive
(or it hangs), but there's really not much required.
The xserver on the thinclient handles mouse movements, window movements
etcetera. When something is written to the screen, only the changes are
uploaded so it doesn't need much bandwith either.

But put video on it? Animations? 
With no compression of image data, bandwith use goes up the roof.

2 Mbit per client is a very round figure. It all depends on the
applications you want to run and the quality you need from them.
As long as we can get 10 Mbit hubs for free, we're not going to spend
too much money on 10/100 Mbit switches.
At least not when sustainable internet costs for our project schools
limits us to using dial-up modems..

Harald



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