Hi Alex, Yes, TCP sends packets, but VNC doesn't - VNC sends a stream of bytes and the TCP stack is then responsible for splitting that stream into a sequence of packets of an appropriate size for the underlying network.
The problems you're seeing are most likely caused by faulty VPN software not indicating the MTU correctly to the two ends of the connection, resulting in TCP splitting the data stream into chunks that are too large for the VPN. Your best bet is therefore to contact your VPN vendor for support for their product. Cheers, Wez @ RealVNC Ltd. > -----Original Message----- > From: Alex Pelts [mailto:[EMAIL PROTECTED] > Sent: 26 April 2006 16:50 > To: James Weatherall > Cc: 'S B'; [email protected] > Subject: Re: VNC freezing on Win XP Media Center Edition SP2 > > Well tcp stack sends packets. It all has to do with the single write > length that most likely goes out as a packet. If the write is > large it > will fill one or more full vpn packets that can't be > fragmented and will > be dropped. You can try it yourself. To tell you the truth I am not a > TCP expert so I cant tell you the exact reason. I am sure that if you > run ethereal you can find some clues rather quickly. > > All I know that lowering MTU on my VPN interface fixed these problems. > > Regards, > Alex > > > James Weatherall wrote: > > Hi Alex, > > > > VNC doesn't send packets at all - it runs over TCP. > > > > Cheers, > > > > Wez @ RealVNC Ltd. > > > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] > >> [mailto:[EMAIL PROTECTED] On Behalf Of Alex Pelts > >> Sent: 25 April 2006 19:14 > >> To: James Weatherall > >> Cc: 'S B'; [email protected] > >> Subject: Re: VNC freezing on Win XP Media Center Edition SP2 > >> > >> The VPN has MTU larger than MTU of physical network. Lots of > >> packets are > >> dropped as somehow VNC sends rather large packets. I had > this problem > >> myself until I lowered MTU to below of the physical network MTU. > >> > >> The symptoms were: > >> 1. screen would render half way and then stop. > >> 2. screen updates were extremely slow > >> 3. Connection would go for some short time and then would > be dropped. > >> > >> I am not sure why MTU is causing that effect. I think that > >> VPN packets > >> can not be fragmented so they are dropped and there is a > large packet > >> loss. I am not sure how VNC reacts to large packet loss. > >> > >> Regards, > >> Alex > >> > >> > >> James Weatherall wrote: > >>> Hi Alex, > >>> > >>> Can you provide any more information on why that causes the > >> effect SB is > >>> seeing? > >>> > >>> Cheers, > >>> > >>> Wez @ RealVNC Ltd. > >>> > >>> > >>>> -----Original Message----- > >>>> From: [EMAIL PROTECTED] > >>>> [mailto:[EMAIL PROTECTED] On Behalf Of Alex Pelts > >>>> Sent: 25 April 2006 07:07 > >>>> To: S B > >>>> Cc: [email protected] > >>>> Subject: Re: VNC freezing on Win XP Media Center Edition SP2 > >>>> > >>>> MTU is too large on your vpn connection. > >>>> > >>>> Regards, > >>>> Alex > >>>> > >>>> > >>>> S B wrote: > >>>>> Hi, > >>>>> > >>>>> I just bought a new computer from Dell (Intel dual core > >>>> 2.8GHz, 1GB RAM > >>>>> running Win XP Media Center w/ SP2), and downloaded VNC 4.4 > >>>> viewer on it. > >>>>> When I VNC to my work machine, VNC viewer freezes > >>>> intermittently. Some times > >>>>> immediately after logging in and some times after 10-15 > >>>> minutes of work. Did > >>>>> anyone here faced a similar problem? How do I fix this problem. > >>>>> > >>>>> Thanks, > >>>>> - SB > >>>>> _______________________________________________ > >>>>> VNC-List mailing list > >>>>> [email protected] > >>>>> To remove yourself from the list visit: > >>>>> http://www.realvnc.com/mailman/listinfo/vnc-list > >>>> _______________________________________________ > >>>> VNC-List mailing list > >>>> [email protected] > >>>> To remove yourself from the list visit: > >>>> http://www.realvnc.com/mailman/listinfo/vnc-list > >>> _______________________________________________ > >>> VNC-List mailing list > >>> [email protected] > >>> To remove yourself from the list visit: > >>> http://www.realvnc.com/mailman/listinfo/vnc-list > >> _______________________________________________ > >> VNC-List mailing list > >> [email protected] > >> To remove yourself from the list visit: > >> http://www.realvnc.com/mailman/listinfo/vnc-list > > _______________________________________________ > > VNC-List mailing list > > [email protected] > > To remove yourself from the list visit: > > http://www.realvnc.com/mailman/listinfo/vnc-list _______________________________________________ VNC-List mailing list [email protected] To remove yourself from the list visit: http://www.realvnc.com/mailman/listinfo/vnc-list
