[Winpcap-bugs] WinPCAP 4.1 beta on Vista, localhost

[Gianluca Varenni]

  ----- Original Message ----- 
  From: Torsten Jaekel 
  To: winpcap-bugs at winpcap.org 
  Sent: Tuesday, November 13, 2007 1:41 AM
  Subject: [Winpcap-bugs] WinPCAP 4.1 beta on Vista, localhost


  Dear WinPCAP team,

  I am using WinPCAP, version 4.1 beta in order to capture data on an USB RNDIS device. It works fine on XP.
  On Vista (32 or 64 bit, on a Dual Core PC, I have strange trouble:

  - if I capture the data (it is a MPEG-2 Transport Stream) and send it as UDP to another PC (leaving my PC) - all is fine
  - if I send it to "localhost" - the TS is corrupt, I have quite a lot of lost TS packets (discontinuities).

Have you checked if all the traffic is received before sending it to your UDP socket?

  I tried to use a FiFo, to increase the buffer sizes when opening the PCAP device etc. Nothing helps.

  It seems to me, traffic on localhost interfers with WinPCAP driver. 

Well, WinPcap sits in parallel with tcp/ip and cannot directly interfere with it.

  The same effect if I send the data via a Named Pipe to another driver/thread.

I think you meant "process/thread", instead of driver.

  WinPCAP is error free, if I write the captured data into a file. It happens only when UDP sockets are used with destination on the same PC.
  If I stream and record into a file what I have streamed - I see the corrupted data.

  My assumption, sockets to localhost on Vista could be too slow, does not seem to be true. I see that WinPCAP is still using timeouts in case
  nothing was captured and the CPU load is not remarkable high.
  My software seems to be correct, just changing from file write to UDP send with the same parameter creates this trouble.

  Could there be a side effect, streaming to localhost? (but only on Vista, on XP it works)?

I don't think so. Have you checks the capture statistics and see if any dropped packets are reported? What is the traffic rate you are dealing with?

Have a nice day
GV

  Sincerely yours

  Torsten Jaekel

  _______________________________________ 


  Torsten Jaekel
  Broadcom Corporation
  Call: +49 30 30 649 396
  Direct: +1 949 926 8016
  Cell: +49 174 94 33 716
  Email: tjaekel at broadcom.com 




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