[X2go-dev] High Performance SSH/SCP - HPN-SSH

John A. Sullivan III jsullivan at opensourcedevel.com
Mon Jun 28 21:36:54 CEST 2010

On Mon, 2010-06-28 at 20:46 +0200, Mike Gabriel wrote:
> Hi John,
> On Mo 28 Jun 2010 13:47:47 CEST "John A. Sullivan III" wrote:
> >> This is the standard network performance tuning found everywhere. This is
> >> interesting for a saturated server, but will not solve any fundamental
> >> speed issues.
> >>
> >> Br,
> >> Erik
> > I have been wondering if it will help with resilience.  We are having
> > problems where, if the Internet connection starts dropping packets,
> > recovery of the X2Go client is much slower than recovery of other
> > applications such as web browsing.  We have tried playing with
> > ClientAliveInterval and ClientAliveCountMax but that has not helped.
> > Has anyone else been able to make X2Go session more robust across poor
> > quality connections? Thanks - John
> If TCP/IP packets get dropped on the way between source and target  
> host you should primarily get to the bottom of that packet dropping.
> Example: Some internet providers have started oversecuring their  
> network routers (e.g. 1und1 in Germany). The ISPs block ICMP requests  
> totally. This blockage then als includes ICMP Type 3 Code 4 packets  
> (destination unreachable, don't fragment). If these kinds of packets  
> are blocked by some routers on the way the Path MTU Discovery  
> technique will fail which results in packet loss... (and endless  
> timeouts...).
> PMTU discovery -> RFC 1191...
> Being a bit off-topic on the list...
Indeed but sometimes it is beyond our control and we can only complain
to the ISP and back it up with our monitoring data.  Thus, we need to
build as resilient an infrastructure as we can.  Thanks - John

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