[Winpcap-users] WinPCap dropping packets UNLESS USB device

Thu Jan 20 12:50:51 PST 2011

Are you using XP? If so, this KB can apply to the issue.

http://support.microsoft.com/kb/895980

GV

-----Original Message-----
From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Frame, Jerry
Sent: Thursday, January 20, 2011 12:45 PM
To: winpcap-users at winpcap.org
Subject: Re: [Winpcap-users] WinPCap dropping packets UNLESS USB device

Thanks Mark.  I actually determined the issue today.  It actually ended being a bios setting, but I'll elaborate a little just in case it helps anyone else.

In my original message, I had stated that Wireshark showed the broadcast was correct when ran on the local HP PC (IE, the one running the app that generates the broadcast.)  What I discovered was that although Wireshark labeled the time between packets as ~100 MS, it was wrong.  When I ran the local HP with Wireshark next to my laptop running Wireshark, the messages came in simultaneously (as expected), but while the local HP would say each packet was about 100 MS apart, my laptop showed them to be anywhere from 250 to 600 MS.  When I insert a USB drive, the timing corrects itself, messages come in noticeably faster, and both PCs show 100 MS between packets.

A friend of mine ran into an article on some forum that mentioned how the timing of multi-core processors can get out of sync if the processors are configured to go into a low power mode if they are not being used.  Sure enough, I went into the bios, disabled this, and it all worked as it should with no USB device plugged in.  I'm not sure why plugging in a USB device fixed the issue, unless the act of plugging in a new device "woke" everything up.

Thanks,

Jerry

-----Original Message-----
From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of winpcap-users-request at winpcap.org
Sent: Thursday, January 20, 2011 3:00 PM
To: winpcap-users at winpcap.org
Subject: Winpcap-users Digest, Vol 70, Issue 6

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Today's Topics:

   1. Re: WinPCap dropping packets UNLESS USB device	pluggedin?
      (Mark Pizzolato - WinPCap-Users)

----------------------------------------------------------------------

Message: 1
Date: Thu, 20 Jan 2011 09:01:36 -0800
From: "Mark Pizzolato - WinPCap-Users"
	<winpcap-users-20040408 at subscriptions.pizzolato.net>
To: <winpcap-users at winpcap.org>
Subject: Re: [Winpcap-users] WinPCap dropping packets UNLESS USB
	device	pluggedin?
Message-ID:
	<78FD0775812F9E429FF9F5E1AA158DBE4099CE at redroof.alohasunset.com>
Content-Type: text/plain; charset="us-ascii"

Hi Jerry,

Just a shot in the dark here, but a possible one....

Compile and run the below program.  See if you get the correct 10hz behavior while that program is running...  

Good Luck,

-          Mark Pizzolato

Link this with Winmm.lib

#include <windows.h>

main(int argc, char **argv)

{

timeBeginPeriod (1);

while (1) Sleep(1000000);

}

From: winpcap-users-bounces at winpcap.org
[mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Frame, Jerry
Sent: Thursday, January 20, 2011 5:51 AM
To: winpcap-users at winpcap.org
Subject: [Winpcap-users] WinPCap dropping packets UNLESS USB device pluggedin?

I've ran into a very odd situation with WinPCap 4.1.2.  I have a several quad core HP computers running a WinPCap based application that sends a broadcast UDP message at 10hz.  For some reason on these HP machines, instead of the broadcast (192.168.x.255) coming out of the NIC at 10hz, the traffic only seems to be at 1-3hz (this is displayed on our embedded
system.)  If I run Wireshark on the local HP PC though, I clearly see a packet every 100 ms.  However, if I run Wireshark on another PC connected to the same network, it confirms the 1-3 hz issue.  Here's the really strange thing.  If I plug in a USB drive, or a USB network adapter (even though I'm not using it), the broadcast starts working normally (10 hz).  Unplug the USB device, and it drops back down.  I ran a test application that uses basic Winsock (the Delphi Indy components to be exact), and it always seems to work fine.

Any suggestions are greatly appreciated.

Thanks,

Jerry

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