[X2go-User] Antw: Re: Usability with latency ~200ms

[John A. Sullivan III]

On Mon, 2011-11-14 at 13:14 +0100, Stefan.Klingner at brodos.de wrote:
> Hi John,
>  
> thanks for your answer.
>  
> Could you please provide some sources for
>  
> "and any tweaks one can make to the IP stack or the SSH protocol. "
>  
> ?
>  
> Regards,
>  
> Stefan

On high bandwidth, high latency links, one generally wants to enlarge
the windows size to help compensate somewhat for the latency.  I've
never done a packet size analysis on X2Go but I would guess this could
help with large screen transfers.  Honestly, I've never taken a look at
what WAN optimizations are available for SSH.  If anyone knows of any,
please share them.  Thanks - John
> 
> >>> "John A. Sullivan III" <jsullivan at opensourcedevel.com> 12.11.2011
> 03:28 >>>
> 
> On Fri, 2011-11-11 at 14:21 +0100, Stefan.Klingner at brodos.de wrote:
> > Hi,
> >  
> > we are trying to use X2Go to provide a devolpment environment for
> our
> > employees in India. The problem is that the connection to India is
> > really bad (latency ~200ms) and so working with X2Go is currently
> not
> > possible.
> >  
> > Is there a way to improve the performance on the X2Go client/server
> > configuration? Does anybody have experience with such a szenario?
> >  
> > Please help.
> <snip>
> The first thought is the usual WAN improvements such as WAN
> accelerators
> and any tweaks one can make to the IP stack or the SSH protocol.  Also
> try to use hard wired connections on the client side rather than
> wireless.  We have seen a tangible difference on the same Internet
> connection between the two.
> 
> However, I am beginning to wonder if something important has changed.
> Our experience with the older 3.0.1 series clients was that they were
> adequate with 200ms latency and packet loss up to 4-5%.  We are still
> running the older server but have started using the newer client.  I'm
> currently using the version in the heuler repository.  I've noticed
> different and troubling behavior which I am guessing is a result of
> the
> switch to libssh.
> 
> My Internet connection has been a little less stable than usual lately
> and I've started to notice really problematic behavior.  I do not know
> why but, if we start experiencing moderate packet loss or latency, the
> behavior is almost as if nagle is enabled.  We'll type a series of key
> strokes and they will all type but the last one.  Two seconds later,
> the
> last key appears - makes editing documents a dangerous nightmare as
> the
> cursor is usually one character off from where one thinks it is.  We
> also see major screen painting delays - clicking on some action and we
> know the server has responded instantly but the old screen just sits
> there for two or three seconds and then suddenly changes.
> 
> We've not had the time to track it down and I'm guessing it will be a
> bear to find but something has definitely changed in the newer client
> code and not for the better - John
> 
> 
>