vnc-list-digest V1 #1422

Chris Jaecker cjaecker "at"
Fri, 25 Jan 2002 01:57:37 +0000


They lied to you. IPSEC is a tunnelling protocol, and carries VNC via TCP 
over IP. What's happening is the data from VNC is being sent in a container 
that is too big to fit into IPSEC's payload. So it's being broken into 
2  and put into 2 datagrams, and reassembled by your VNC client. This is 
inefficient and causes problems for the client (data is late, 
acknowledgements are late, TCP on VNC client and server times out).

There's an old saying: "You can't put a quart into a pint pot". Reduce the 
MTU and you will be fitting a pint into a pint pot.

Given what they told you I am 100% sure this is your problem.


At 10:20  24/01/02 +0000, you wrote:
>Date: Thu, 24 Jan 2002 10:30:27 -0500
>From: mpatient "at"
>Subject: RE: MTU - VNC dies and requires reconnection every few minutes (W 
>in NT - AT T Extranet - Cable Modem)
>Chris and Mark,
>Regarding MTUs. I'm not working at that knowledge level, so I asked our
>technical support people...
>They said we are not using TCP/IP for transport. Instead, we are using
>"IPSEC" and the data is both encrypted and encapsulated for transport.
>Thanks for the "shot in the dark". I'm still looking for the light switch...
>Mike Patient
>Solutions Engineer
> > *     Email : mpatient "at"
> > *     Phone:          407.805.1558
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