[Winpcap-users] Strange packets timing

Gianluca Varenni gianluca.varenni at cacetech.com
Wed Jan 28 21:07:21 GMT 2009


The capture mechanism certainly introduces a non-constant delay in the timestamps, but if you transmit at a fixed rate, you must see that fixed rate over time. So, if you are transmitting 1 packet every 10ms, in 10 seconds you should definitely see around 100 * 10 = 1000 packets. Have you made this experiment?

Have a nice day
GV
  ----- Original Message ----- 
  From: Franz P 
  To: winpcap-users at winpcap.org 
  Sent: Monday, January 26, 2009 2:47 AM
  Subject: [Winpcap-users] Strange packets timing


  Hello everybody,
  i am using wireshark 1.0.5 to sniff some UDP traffic that i am generating from an application i'm developing: i am working on a windows xp pro based pc,using visual basic 6 and MS visual studio 6 as my development platform,and using a gigabit NIC (but working in a 100Mbps network).

  My application generates a UDP packet every 10ms:i monitor this timing from my application with an high resolution timer,so i am pretty sure about this timing datum.
  While sniffing the traffic,though,i can clearly see a smaller delta time between each packet (from about 7 to 9ms).

  Before posting i have read about wireshark timestamps,finding out they are taken from winpcap (from the wireshark wiki:"Wireshark just gets its timestamp from libpcap/WinPcap, and libpcap/WinPcap gets it from the packet capture mechanism it uses; Wireshark itself doesn't generate the timestamp so there's nothing Wireshark can do about it.").

  Besides,i have read the post at http://www.mail-archive.com/[email protected]/msg02490.html ,which seems to be related to my problem.


  I just find it strange that i can see a smaller delta time....i wouldn't be surprised if that would be higher....
  Why does it happen?
  Thanks in advance!


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