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RE: [LUG] VNC



Use tight vnc for slower connections

I use VNC remotely over my adsl connection on my linux machine and its very
quick but I run the blackbox desktop in 8 bit colour.  On windows machines
there are some options to stop vnc refreshing the whole screen which helps
considerably, these are available by double clicking the VNC icon in the
taskbar of the server machine.

Regards
Kelly


-----Original Message-----
From: owner-list@xxxxxxxxxxxx [mailto:owner-list@xxxxxxxxxxxx] On Behalf Of
Neil Stone
Sent: 22 November 2003 10:20
To: list@xxxxxxxxxxxx
Subject: Re: [LUG] VNC

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Simon Robert wrote:
> Hi
> do any of you have experience using vnc? It looks great, you can have 
> lots of PC's, thin clients, whatever running linux gnome/kde/whatever 
> sessions.
> 
> I thought that the tricky bit would be configuring it, but not so. With 
> linux 9 the vnc server stuff comes as standard and configuring it all 
> took about 4 minutes. I set it up PC to linux server at the office and 
> all was good.
> 
> However out on a client site with a far more powerful machine running as 
> the linux server it runs like a one legged dog!
> 
> The problem maybe to do with xwindows, in that the kde desktop just 
> ain't getting the resources and priorities it needs in terms of memory 
> etc. The graphical login screen jumps up nice and fast, after that 
> though you could make and drink a cup of tea between the display of each 
> line of the kde gui. As for the mouse move it from one side of the 
> screen to the other and you can go off for 10 minutes while the 
> graphical pointer catches up with the movement.
> 
> It doesn't seem to be a network problem as run it in text mode and it 
> seems to go at normal speed, i.e. do a find or list things. So anyone 
> got any ideas on what to do... ?

I have used the linux vncserver and vncviewer software a fair bit... one 
thing I have found however..

Because of the way VNC works, it can be very intensive when running on a 
high graphics desktop. ie a jpeg for wallpaper, lots of funky effects.. 
the reason is quite simple.

the VNC server sends blocks of data, screen images, to the client top 
down. it also sends a complete screen refresh if there are non native 
colours used.

eg.
  Black desktop colour (#000000) no animation = very fast
  jpeg image desktop with a gradiant border, and lots of animation = very
   slow

Another thing I have found.. and I am not just having a go for the hell 
of it..

The Microsoft TCP/IP stack seems to generate a lot more traffic than the 
Linux tcp/ip stack. why ? who knows.. perhaps it is because Windows was 
never designed to use TCP/IP from the word go where Linux was ?

If you are interested in remote computeing you may want to look in to 
using X in a remote environment, showing a screen from a "server"

If anyone is interested in this, let me know I'll see if I can answer 
any questions.


Neil

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