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<p class=MsoNormal><span style='color:#0070C0'>Some more information on this
issue...<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'>The function ‘pcap_sendpacket’
is failing up to 40% of the time when sending the streaming multicast packets
to the kernel.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'>Is this a known issue, and is
there a fix??<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'>Tony<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#0070C0'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US 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>Tony Ballardie<br>
<b>Sent:</b> 10 October 2008 12:21<br>
<b>To:</b> winpcap-users@winpcap.org<br>
<b>Subject:</b> [Winpcap-users] winpcap 4.0.2 possible packet loss?<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hi,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Winpcap 4.0.2 is being used on a Windows Server 2008 box to
capture UDP-tunnelled streaming media (IP multicast) packets and then present
de-capsulated/original multicasts for playback in windows media player on box.
Depending on the stream, the bitrate may be 500-600kbps. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The underlying multicast packets are being IP fragmented at source,
so each fragment is UDP-tunnelled so arrives as its own UDP packet, becoming an
IP fragment after tunnel decapsulation. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’m not the developer here but I’m presuming once the
tunnelled packets are decapsulated they are written back to NPF for subsequent
presentation to the IP layer and normal IP processing.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The on-box media player is showing up to 40% packet loss and
wonder if this could be due to the NPF not being capable somehow of processing
packets under these higher bitrate conditions? The path between source and
receiver is just a single-hop LAN and I’m confident the packet loss is not
happening in the network.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Or perhaps certain parameters need setting accordingly?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The network adapter is a Broadcom NetXtreme Gigabit Ethernet
adapter.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Any suggestions would be greatly appreciated.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Tony<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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