Hardware Timestamping Problem

[Christian <christian.rupp.stuttgart () freenet de>]

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

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