[Winpcap-users] Delay and jitter

Gianluca Varenni gianluca.varenni at cacetech.com
Wed Nov 29 21:47:32 GMT 2006


If you need to compute the jitter and delay between packets, you need to process the timestamps attached to each packet (in the pcap_pkthdr header). Regarding a microsecond precision, remember that packets are timestamped not when the board receives them, but when the capture engine in the kernel (being it windows or linux) processes them, and this can introduce a delay of some microseconds (this is due to a number of reasons, e.g. interrupt mitigation, the network card does not generate an interrupt for every received packet, but rather batches the received packets for some microseconds in order not to generate too many interrupts).

Hope it helps
GV
  ----- Original Message ----- 
  From: Antonio Ocampo 
  To: winpcap-users at winpcap.org 
  Sent: Wednesday, November 29, 2006 1:25 PM
  Subject: [Winpcap-users] Delay and jitter



  I need to find the delay and jitter, how can I do this? i've tried to use time.h but it just have precision of seconds and I need precision of microseconds !!! I can't use getimeofday() because my program have to run in windows and linux. 

  Another trouble, when I tried to use the fields of the struct pcap_stat

  if_drop: it shows me 0 always
  bs_cap: it doesn't compile

  Any suggestions? I really need your help. Thanks in advance


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