[Winpcap-users] winpcap 4.0.2 possible packet loss?

Gianluca Varenni gianluca.varenni at cacetech.com
Mon Oct 13 20:20:04 GMT 2008


Do you have more details on the network card you are using (brand and model)?

Have a nice day
GV
  ----- Original Message ----- 
  From: Tony Ballardie 
  To: winpcap-users at winpcap.org 
  Sent: Friday, October 10, 2008 1:43 PM
  Subject: RE: [Winpcap-users] winpcap 4.0.2 possible packet loss?


  Some more information on this issue...

   

  The function 'pcap_sendpacket' is failing up to 40% of the time when sending the streaming multicast packets to the kernel.

   

  Is this a known issue, and is there a fix??

   

  Tony

   

   

  From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Tony Ballardie
  Sent: 10 October 2008 12:21
  To: winpcap-users at winpcap.org
  Subject: [Winpcap-users] winpcap 4.0.2 possible packet loss?

   

  Hi,

   

  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. 

   

  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. 

   

  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.

   

  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.

   

  Or perhaps certain parameters need setting accordingly?

   

  The network adapter is a Broadcom NetXtreme Gigabit Ethernet adapter.

   

  Any suggestions would be greatly appreciated.

   

  Thanks

   

  Tony

   



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