#147 Maintaining a Connection

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nobody
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5
2012-11-29
2005-12-28
No

I have some strange problems with my rdesktop
connection to a remote computer over the internet.

I can normally connect up, although this is not 100%
and is sometimes quick and sometimes slow. After a few
seconds the connection then appears to be lost in that
events sent to the remote computer do not register on
that machine and screen refreshes do not occur. At the
same time the keyboard is "locked" into the rdesktop
connection, and so typing in a local window is not
possible. The connection may or may not re establish
itself. Sometimes it is necessary to kill the rdesktop
and re connect.

My difficulty is how to diagnose the problem. I have
run traceroute to the other machine every five seconds
for a day and it does not appear to fail. I have pinged
the other machine for a similar period and the average
response time is around 80ms running up to 129ms. How
can I find out why the connection is being lost? All
internet use appears normal, large file downloads occur
without problems.

Running Mandrake 10.1 and rdesktop 1.3.1

Thanks for any help you may be able to give

Andrew

Discussion

  • Ilya Konstantinov

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    We really don't have the resources to support version below
    the current one. Can you upgrade to rdesktop 1.4.1 and test
    it again?

    Also, it's sometimes helpful to mention what system you're
    connecting to.

     
  • Andrew Myers

    Andrew Myers - 2005-12-28

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    OK I have upgraded to 1.4.1 and will let you know if there
    is any difference in the behaviour. I am connecting to
    Windows 2003 Server acting as a terminal server.

     
  • Andrew Myers

    Andrew Myers - 2005-12-29

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    Sorry to say that the upgrade made no apparent difference.
    How can I trace what is breaking the connection? Or is there
    a way of forcing it to be maintained?

     
  • Andrew Myers

    Andrew Myers - 2006-01-01

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    I have to assume that my ADSL connection is a bot ropey,
    although it does not appear to affect anything else very badly.

    Do you have any suggestions as to the best settings/method
    to use to maintain a connection?

     
  • Nobody/Anonymous

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    Have you tried reducing the MTU?

     
  • Andrew Myers

    Andrew Myers - 2006-01-02

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    Can you tell me what that is and how I would do it? :-?

     
  • Nobody/Anonymous

    Logged In: NO

    Because your problems are intermittent, and you don't see a
    problem with web browsing or file transfers, your problem is
    probably do to packet fragmentation.

    RDP, VNC, etc... these services fail/degrade in performance
    very quickly when there is fragmentation. Ping will not tell
    you much about fragmentation problems actually it's worse,
    it won't detect them.

    If ICMP messages are not being blocked between your terminal
    server and your client, then you should be able to analyze
    the traffic to see if fragmentation is occuring. It depends
    on what is between you and the server (ie the
    firewalls/routers in between). Tools like tcpdump (use
    ethereal if you like a gui interface) and snmp tools will
    help you diagnose the problem.

    By changing the MTU size, you are reducing the size of the
    packet, thus reducing the chance of fragmentation. Of
    course if you reduce it too much your performance will
    degrade as well.

    How you change your MTU depends on the path to the server.
    It should be done on your router if possible. If you are
    connecting to the Terminal Server through a vpn, then change
    the MTU on the vpn interface.

     
  • Andrew Myers

    Andrew Myers - 2006-01-03

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    Right - firstly, thank you very much for the detailed
    response. I really appreciate you taking the time.

    Secondly, this is complicated so I will need to go and do
    some research, but it sounds like you have the answer in
    here somewhere. I have intalled ethereal and will see what I
    can make of that.

    Andrew

     
  • Andrew Myers

    Andrew Myers - 2006-01-11

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    user_id=886899

    Just an update, I have changed my MTU to 1048 and the link
    is staying up, if somewhat "jerkily". I need to refine this now.

    Is small bad, large good?

    Any recommendation as to the best size, or is it trial and
    error?

    How do I know what the default setting is?

    Thanks again

    Andrew

     

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