Very Slow ACK on QNX 4.25


I’ve seen occasional TCP reply slowdown when using QNX as the server,
and SunOS8 as the client. They’re communicating using TCP socket. The
ACK from QNX box occasionally doesn’t show up until 10+ seconds later.
It doesn’t happen very often, but once in several minutes to several

Could someone give any clue as to what might be the problem, and how I
can fix it?


  • John

On Thu, 29 Nov 2007 00:55:19 +0300, johnxyu
<> wrote:

Could someone give any clue as to what might be the problem, and how I
can fix it?
What is your “sin ve” report?

If you are using the TCP v4.25D - I’d suggest to upgrade to the TCP v5.0,
a much more stable and advanced version.


Thanks Tony.

Here’s the output for “sin ve”:
/boot/sys/Proc32 Proc 4.25J Sep 09 1999
/boot/sys/Proc32 Slib16 4.23G Oct 04 1996
/boot/sys/Slib32 Slib32 4.24B Aug 12 1997
/bin/Fsys Fsys32 4.24V Feb 18 2000
/bin/Fsys Floppy 4.24B Aug 19 1997
/bin/Fsys.eide eide 4.25A Feb 09 2000
//1/bin/Dev32 Dev32 4.23G Oct 04 1996
//1/bin/Pipe Pipe 4.23A Feb 26 1996
//1/bin/Dev32.ser Dev32.ser 4.23I Jun 27 1997
//1/bin/Dev32.ser Dev32.ser 4.23I Jun 27 1997
//1/Comtrol/Dev32.rckt Dev32.rckt 4.25D Dec 04 2003
//1/bin/Dev32.ansi Dev32.ansi 4.23H Nov 21 1996
//1/bin/Dev32.par Dev.par 4.26 Feb 24 2000
//1/bin/Dev32.pty Dev32.pty 4.23G Oct 04 1996
//1/bin/Iso9660fsys Iso9660fsys 4.23D Mar 20 2000
//1/bin/Dosfsys Dosfsys 4.23E Jan 21 1997
//1/bin/cron cron 4.23B Oct 30 1997
//1/bin/Net Net 4.25C Aug 30 1999
//1//Net.ether82557a Net.ether825 4.25F Aug 30 1999
//1/bin/Mqueue mqueue 4.24A Aug 30 1999
/usr/ucb/Socklet Socklet 4.25H Jul 30 1999

How do I upgrade?

On Fri, 30 Nov 2007 00:55:09 +0300, johnxyu
<> wrote:

//1/*/usr/ucb/Socklet Socklet 4.25H Jul 30 1999
Seems, it is the TCPv4.25D.

On “myQNX” site you should be able to obtain the most recent TCPv5.0,
untar it.
Just one gotcha to be aware of: if you do not have the “Security update”
(the newer “login”, “passwd” and “su”) - you will have problems loging-in
via “telnet v5”.

If you can - I’d advise you to apply all the relevant updates, your system
looks far too outdated…


Upgrade for us can be difficult, but definitely worth shooting for.

In the meanwhile, when I do stat, I saw this: TCP 268442 ack-only
packets (253769 delayed)

Is this normal? Is there any parameter to tune?