[Winpcap-users] PPP capture

[Gianluca Varenni]

Anton,

If I remember well, you are capturing from Ethernet, Akif is capturing from PPP. The code paths for the two types of devices are completely different (Ethernet goes through the WinPcap kernel driver, PPP gets captured through Netmon).

Have a nice day
GV

From: Anton Tremsin [mailto:ast at ssl.berkeley.edu]
Sent: Monday, March 14, 2011 11:43 PM
To: winpcap-users at winpcap.org
Cc: Gianluca Varenni
Subject: Re: [Winpcap-users] PPP capture

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> [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<mailto: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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