[Winpcap-users] Problems with timestamps

Juha Yli-Penttilä juha.yli-penttila at tut.fi
Fri Jan 16 14:13:11 GMT 2009

Hi all,

I'm doing TCP RTT analysis for EGPRS connection. I have used Wireshark  
1.5 + WinPcap 4.0.2 for capturing the logs files, but I encountered  
some problems regarding timestamps. The problems seems to be in  
timestamp resolution, that is, multiple packets are captured with the  
same timestamp. An example:

613	30.734375
614	30.765625
615	30.765625
616	30.796875
617	30.828125
618	30.828125
619	30.859375
620	30.890625
621	30.890625
622	30.921875
623	30.953125
624	30.953125

It seems that timestamps are somehow rounded to certain values. That  
is a problem when calculating RTT estimates, because data segment and  
acknowledgement may have the same timestamp. I am using Windows XP  
SP2. As far as I know, the timestamps have been ok in some older  
Windows OS (maybe 98 or 2000). The timestamps seem to be ok also in  
Linux. So basically my question is: is there an easy way the change  
timestamp resolutions in Windows XP? Also, can somebody tell if some  
other Windows OS (or other WinPcap) version suits my needs better or  
is the easiest way to just use Linux? Thanks in advance.

PS. I am not so familiar with source code modifications or compiling  
my own build, so by easy way I mean something else than those.  
However, if source code modification is needed, instructions are  

Juha Yli-Penttilä

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