Hello,
(Sorry if this shows up twice, I wasn't registered for the List, when I
first sent my request.
And sorry if this is the wrong place for this kind of question.)
I'm currently working on my Bachelors Thesis.
The aim of my project is to accuratly and precisely timestamp
Packages(it has to be at least precise in the tenth of microsecond range).
I am trying to accomplish hardware timestamping with tcpdump, but there
are some problems I have encountered.
My Setup:
2 directly connected identical Servers.
Linux: Debian 3.16.7
Network Interface: Intel i350-T4
Used tcpdump command:
sudo /usr/sbin/tcpdump -i eth4 -s 59 port 33333 -x -n -tt -v -j
adapter_unsynced --time-stamp-precision=nano -w name.pcap
Now, my results in itself make sense and would give me the desired
results, but they have a big offset to them. 36 seconds to be exact.
The jitter of my results with the -j adapter_unsynced option are about
10 µs,
If I use the -j adapter option I get a Jitter of ~100µs( too imprecise
for my application), but not the 36 second offset.
All clocks are syncronised as far as I can see.
The system clocks were both syncronised, and the PHC Clock of the NIC
was too.
As a test run I changed the system clock of one of the servers and the
change showed up on the results while using -j adapter_unsynced.
So my question is: What am I doing wrong, and is what I want to do even
possible with tcpdump?
I'm thankfull for any advice.
Greetings,
Christian
_______________________________________________
tcpdump-workers mailing list
tcpdump-workers@lists.tcpdump.org
https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
