On 07/18/2014 03:49 PM, Tobias Klauser wrote:
On 2014-07-18 at 15:09:55 +0200, 'peter' via netsniff-ng
<netsniff-ng@googlegroups.com> wrote:
hi,
im looking for a way to automate packet generation for traffic
shaper testing.
found a testfile online and modified it a bit, only
source/destination ip are valid for the interface ...the rest is
from the sourcefile so there are wrong mac addresses and so on.
for traffic shaping testing (HFSC) i only need a mix of small / big
packets that i can capture and graph.
its udp, its 322bytes long (according to trafgen output).
when i run:
trafgen --cpp --dev wlan0 --conf packets/322bytes -t 10ms -n 10
and:
tcpdump -i wlan0 port 7777
it shows 10 packets, each about 10ms apart from another but it takes
some seconds before the packets show up in tcpdump...why is that?
You are running this on the same machine? Note that trafgen (at
least recent versions) bypass the qdisc layer completely and thus
you *won't* be able to see the traffic from that looped back into
packet sockets (and thus libpcap/tcpdump).
Have you tried running tcpdump on a different machine (e.g. the
receiving end)?
Any specific reason you're using tcpdump instead of netsniff-ng? ;-)
running the same command with "-n 100" i get:
31 packets captured
100 packets received by filter
69 packets dropped by kernel
when aborting tcpdump with ctrl+c.
why would the linux kernel drop packets? since they are 10ms apart
and 322bytes long it should manage?
it not like i send 1000 packets without time between sends or am i
hitting some limitation?
What does the trafgen config file look like? What kernel version are you
using? What driver for wlan0? What version of
netsniff-ng/trafgen/tcpdump?
Without this information it's gonna be rather difficult to pinpoint the
problem...
Cheers
Tobias
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