[Winpcap-users] Winpcap-users Digest, Vol 72, Issue 7

Akif Usman akif.usman at hotmail.com
Wed Mar 16 02:08:25 PDT 2011 

HI,
There are some questiosn i need to ask. Why does wireshark give no delay upon capture even though it uses Winpcap? 
I am using windows xp for capture and i have checked the capture on ethernet and there seems to be no problems at all from the capture on ethernet. I have tried changing mintocopy and the timeout but it gives me no changes in the performance? Any ideas why?

BR

> From: winpcap-users-request at winpcap.org
> Subject: Winpcap-users Digest, Vol 72, Issue 7
> To: winpcap-users at winpcap.org
> Date: Tue, 15 Mar 2011 12:00:02 -0700
> 
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> Today's Topics:
> 
>    1. Re: PPP capture (Gianluca Varenni)
>    2. Re: PPP capture (Anton Tremsin)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Mon, 14 Mar 2011 18:44:54 -0700
> From: Gianluca Varenni <Gianluca.Varenni at riverbed.com>
> To: "winpcap-users at winpcap.org" <winpcap-users at winpcap.org>
> Subject: Re: [Winpcap-users] PPP capture
> Message-ID:
> 	<6A8F2E88CFF83C43A6AFF7FAC775B9FC07151739AA at MAILBOXES2.nbttech.com>
> Content-Type: text/plain; charset="us-ascii"
> 
> Akif,
> 
> This is probably due to the mintocopy and timeout of WinPcap. WinPcap does not deliver you the packets immediately after they are received by the driver. Packets are batched in kernel mode and delivered to the receiving application when
> 
> 
> -          There are at least mintocopy bytes in the kernel buffer
> 
> -          After a certain timeout
> (whatever happens first).
> 
> In order to reduce the delay, you will need to either reduce the timeout or the mintocopy.
> 
> Have a nice day
> GV
> 
> From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Akif Usman
> Sent: Thursday, March 10, 2011 11:20 AM
> To: winpcap-users at winpcap.org
> Subject: [Winpcap-users] PPP capture
> 
> HI,
> 
> I have installed the winpcap version 3.1 beta and i am capturing from a PPP interface and it captures perfectly. Now i am trying to capture from the same PPP interface using my LIBPCAP program and forward it to another Ethernet interface that connects  further to a second computer (Ethernet NIC) which also has wireshark running on it. When i capture from the second computer i get a strange offset of 0.5 seconds after every x packets. This is very strange. I dont know why wireshark is able to capture from PPP interface on the first computer with proper accuracy and why my LIBPCAP program, which is just forwarding the packets, is introducing a 0.5s [:-O] delay. Please help me out as soon as somebody can.
> 
> Best Regards
> Fika
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> ------------------------------
> 
> Message: 2
> Date: Mon, 14 Mar 2011 23:42:30 -0700
> From: Anton Tremsin <ast at ssl.berkeley.edu>
> To: winpcap-users at winpcap.org
> Cc: Gianluca Varenni <Gianluca.Varenni at riverbed.com>
> Subject: Re: [Winpcap-users] PPP capture
> Message-ID: <4D7F0A56.1070207 at ssl.berkeley.edu>
> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
> 
> Akif, Gianluca,
> 
> As I mentioned in my previous messages, I have exactly the same problem 
> of delayed packages, with mintocopy set even to 0 (tried other values as 
> well). I am always sending  a set of 64 packets of 8Kbytes each (that is 
> one image data). The packets are not lost, they always arrive. However, 
> some of them come with no delay (varied number of them, sometimes 62, 
> sometimes 57, etc), while the rest of them come exactly after the delay 
> equal to the setting of the timeout, which I varied between 1 and 10000 
> milliseconds. There is no timeout reported for the packets to arrive 
> with the delay.
> 
> I will be very glad if that issue can be solved, which has probably the 
> same cause as in Akif's application.
> 
> Thanks a lot,
> 
> Anton
> >
> > Akif,
> >
> > This is probably due to the mintocopy and timeout of WinPcap. WinPcap 
> > does not deliver you the packets immediately after they are received 
> > by the driver. Packets are batched in kernel mode and delivered to the 
> > receiving application when
> >
> > - There are at least mintocopy bytes in the kernel buffer
> >
> > - After a certain timeout
> >
> > (whatever happens first).
> >
> > In order to reduce the delay, you will need to either reduce the 
> > timeout or the mintocopy.
> >
> > Have a nice day
> >
> > GV
> >
> > *From:* winpcap-users-bounces at winpcap.org 
> > [mailto:winpcap-users-bounces at winpcap.org] *On Behalf Of *Akif Usman
> > *Sent:* Thursday, March 10, 2011 11:20 AM
> > *To:* winpcap-users at winpcap.org
> > *Subject:* [Winpcap-users] PPP capture
> >
> > HI,
> >
> > I have installed the winpcap version 3.1 beta and i am capturing from 
> > a PPP interface and it captures perfectly. Now i am trying to capture 
> > from the same PPP interface using my LIBPCAP program and forward it to 
> > another Ethernet interface that connects  further to a second computer 
> > (Ethernet NIC) which also has wireshark running on it. When i capture 
> > from the second computer i get a strange offset of 0.5 seconds after 
> > every x packets. This is very strange. I dont know why wireshark is 
> > able to capture from PPP interface on the first computer with proper 
> > accuracy and why my LIBPCAP program, which is just forwarding the 
> > packets, is introducing a 0.5s [:-O] delay. Please help me out as soon 
> > as somebody can.
> >
> > Best Regards
> >
> > Fika
> >
> >
> > _______________________________________________
> > Winpcap-users mailing list
> > Winpcap-users at winpcap.org
> > https://www.winpcap.org/mailman/listinfo/winpcap-users
> >    
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