Can you reproduce the same issue with the sample 
WpdPack\Examples-remote\PacketDriver\TestPacketSend in the WinPcap developer's 
pack?

Have a nice day
GV


From: Imre Magyar 
Sent: Friday, April 16, 2010 11:16 AM
To: [email protected] 
Subject: Re: [Winpcap-users] losing transmitted packets


I've tried it on various PC network interfaces, including a 10/100 USB network 
dongle and 2 different GigE PCI motherboard-based interfaces. Different 
combinations of PCs and adapters result in a different number of frames getting 
through, but the number is far less than half in all cases.

 

--I. M.

 

 


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

From: [email protected] 
[mailto:[email protected]] On Behalf Of Gianluca Varenni
Sent: Friday, April 16, 2010 1:13 PM
To: [email protected]
Subject: Re: [Winpcap-users] losing transmitted packets

 

What kind of network card are you using on the transmitter machine? can you 
reproduce it with different network cards?

 

GV

 

From: Imre Magyar 

Sent: Friday, April 16, 2010 11:04 AM

To: [email protected] 

Subject: [Winpcap-users] losing transmitted packets

 

Hello all,

 

I have a win32 app that calls pcap_send() in a tight loop repeatedly, on the 
same 1400 byte frame, say 1000 times.

 

The PC is wired directly to an embedded 10/100 network device, but I do have a 
port aggregating tap device in between for monitoring. There are no switches or 
hubs involved at all.

 

I'll run the win32 app, and see that only a small fraction (say 500) of the 
frames are reported as received on the device at the other end.

 

If I run wireshark on the tap device, I see that the receiving device reported 
the frame count accurately. Only 500 went out on the link.

 

If I run wireshark on the PC on the same interface the app is sending the 
frames on, I see all 1000 frames.

 

If I insert a small delay in the app between pcap_send() calls (say I call 
Sleep(1) for a millisecond's worth of delay), all 1000 frames go out on the 
link, albeit much slower than I'd like.

 

Can anyone tell me what is dropping the frames and why? I'm assuming I'm 
overrunning some internal transmit buffer somewhere, but I'm at a loss to 
understand how to recognize it and when to back off. The pcap_send() function 
never returns with an error.

 

Thanks for any advice,

 

--Imre M.

 


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