Hi Alex,
thanks for your quick reply. It helped a lot! See some comments inline.
Am 07.04.2016 um 22:41 schrieb Alexander Aring:
On Thu, Apr 07, 2016 at 10:19:35PM +0200, Peter Kietzmann wrote:
Dear list,
first of all let me say that I'm new to this list. So if I'm completely
wrong in my concern please excuse the noise and guide me to the right place.
If you can :-)!
For some experiments I'm trying to send "great" numbers of UDP packets with
"great" payloads as fast as possible from a RasPi equipped with the Openlabs
transceiver. With another RasPi+transceiver I'm sniffing the traffic. It
turns out that just the first x packets are sent out correctly before the
outgoing packets come out irregularly. The number of correctly sent packets
depends on the UDP payload size and it looks like the problem occurs after
~30-35 kB Bytes (gross) in total have been transmitted (fragmentation
overhead included). I already increased the send socket memory to a
reasonably high value, without success. But still I assume some buffer
problems. Do you have a hint which screw to adjust?
BTW: Introducing a delay after each packet to send fixes the problem. But
I'd like to do stress-testing...
1.
You cannot be sure that a monitor interface shows all traffic which is
on the air. You have at least hardware limitations which begins at
"rising IRQ" and ends at "framebuffer readed".
I totally agree. But here it was quite obvious something was going on
after some time.
2.
Try to enable ack request bit. This is default disabled because you need
to know what you doing when you enable it. Be sure all nodes supports
ACK handling before that.
You can do that with:
iwpan dev $WPAN_DEV set ackreq_default 1
Found out that my sender Pi doesn't support this option. Guess I should
update it...
3.
Change tx queue setting:
ip link set txqueuelen 1000 dev $WPAN_DEV
That was the parameter I was looking for. Increasing this queue it is :-) !
Please reply if that helped you otherwise we will maybe find another
tweaks. :-)
- Alex
Again, thanks for your quick help!
Cheers
Peter
--
Peter Kietzmann
Hamburg University of Applied Sciences
Dept. Informatik, Internet Technologies Group
Berliner Tor 7, 20099 Hamburg, Germany
Fon: +49-40-42875-8426
Web: http://www.haw-hamburg.de/inet
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