VNC under HP-UX problems: core dump / IP address only

James [Wez] Weatherall jnw "at"
Fri, 31 Jul 1998 11:22:14 +0000

On Wed, 29 Jul 1998, Guenter Steinbach wrote:

> Problem 2:
> >From my PC (NT4sp3) I cannot connect to my workstation by name, only by
> its IP address - why not?  I can access its Samba shares by name, so why
> not the VNC server.

NT VNC viewer -> Unix VNC server?  There's no reason why you should be
able to access the VNC server by name just because your Samba shares are
accessible by name - Windows networking by default uses a different naming
resolution system to the DNS system used for TCP/IP.  The Windows VNC
viewer uses DNS to lookup the name of the server you specify, so if your
machine has no DNS set up, or no HOSTS file set up then the name
resolution will fail.

> And lastly (and maybe connected to the socket issue?), the connection
> from an NT server to an HP-UX viewer is unusably slow.  That can't be
> normal or I would hear so many people sing VNC's praise on this mailing
> list.  I have a 200MHZ Pentium-II, so server horse power shouldn't be
> the issue.

Depends.  Common causes of this problem are:
1) Rogue system processes eating most of the CPU time and leaving little
for WinVNC to use.
2) The user having set all the Polling option to On in the Properties
panel - these options are only used to cope with problem applications and
should not generally be necessary.
3) High latency in the network connection between the machines.
4) Highly colourful or highly dithered backgrounds, buttons or dragbars.
These don't compress much for transmision, resulting in high bandwidth
requirements and hence poor response times.
5) Having set the viewer to request Raw pixel data.

> a Vim window, and tha java viewer is ridiculous, it takes several
> minutes to paint the screen, over a LAN connection.

This sounds very much as if the screen you are remoting contains a great
deal of dithered and therefore difficult to compress data.  The Java
viewer is known to be particularly slow when drawing raw data, unless the
Raw Pixel drawing option is set to Fast, rather than Reliable.


James "Wez" Weatherall
Olivetti & Oracle Research Laboratory, Cambridge, UK.
Tel : Work - 343000

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