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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Pcap_send is synchronous, but it doesn’t wait for the acknowledge on the network (which ACK, by the way?).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The reason why is slow is that you perform a system call per packet, which introduces latency and CPU load. As Michael correctly said, I would explore the use of pcap_queue’s.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Have a nice day<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>GV<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> winpcap-users-bounces@winpcap.org [mailto:winpcap-users-bounces@winpcap.org] <b>On Behalf Of </b>Black, Michael (IS)<br><b>Sent:</b> Wednesday, January 26, 2011 4:54 AM<br><b>To:</b> winpcap-users@winpcap.org<br><b>Subject:</b> Re: [Winpcap-users] EXTERNAL: Limit on packet sending.<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>I'll jump in here...somebody correct me if I'm wrong.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>But...I believe pcap_send is synchronous so you're seeing network latency on the acknowledge.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>You need to look at pcap_sendqueue.... functions. Or just do the windows packet write without using winpcap at all. Pcap is mainly for honoring timestamps which you probably don't care about.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><div><p class=MsoNormal id=""><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>Michael D. Black<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>Senior Scientist<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>NG Information Systems<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>Advanced Analytics Directorate<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> <o:p></o:p></span></p></div></div><div><div class=MsoNormal align=center style='text-align:center'><span style='color:black'><hr size=2 width="100%" align=center></span></div><div id=divRpF15293><p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black'> winpcap-users-bounces@winpcap.org [winpcap-users-bounces@winpcap.org] on behalf of Akif Usman [akif.usman@hotmail.com]<br><b>Sent:</b> Wednesday, January 26, 2011 5:46 AM<br><b>To:</b> winpcap-users@winpcap.org<br><b>Subject:</b> EXTERNAL:[Winpcap-users] Limit on packet sending.</span><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>HI, <o:p></o:p></span></p><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>I am experiencing a problem while writing a program that accepts packets from one ethernet interface puts them in a queue and sends it back to another interface. I am using threading to do this multitasking. The sending thread is very slow, i dont know why!<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>While i use threads and i receive at 50 Mbps i get a total forwarding rate of only 5-7 mbps. Then when i just grab one packet and keep on sending it in one thread (just to test the sending thread), it still gives me 5-10 Mbps . Is it a limitation of pcap_send packet?<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>I am using pcap_loop to receive packets if i want to receive them continuously. But i don;t understand why the sending speed is so low. Please help me i am stuck from quite many days on this.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>Best Regards<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>Fika<o:p></o:p></span></p></div></div></div></div></div></body></html>