On Mon, 19 Apr 2004 08:32:55 -0700 "Pawan Singh" <[EMAIL PROTECTED]> wrote:
I read about "offload TCP segmentation". Does winpcap capture packets before
or after segmentation?
Before, since segmentation is done on the NIC itself.
Have a nice day GV
Pawan Singh [EMAIL PROTECTED] 650 776 3958
-----Original Message-----
From: Gianluca Varenni [mailto:[EMAIL PROTECTED] Sent: Monday, April 19, 2004 4:58 AM
To: [EMAIL PROTECTED]
Subject: Re: [WinPcap-users] Winpcap 3.1 beta: Problem with packet length
and captured length
Hi.
We experienced a similar "problem" with one of our lab machines (using an
intel server Fast Ethernet card). In practice some network cards (server
nics, usually), are able to fragment outbound packets in smaller chunks (I
don't know how, exactly), so they announce to protocol drivers (TCP-IP as
well as winpcap) that the maximum packet size is more than 1514 bytes. As a
consequence, the tcp-ip stack sends "jumbo" packets, and winpcap captures
them (obviously). A workaround to the problem is to disable these features
on the network card (by means of the control panel of the nic driver), if I
remember well it's called "offload TCP segmentation" on my machine.
Hope it helps GV
----- Original Message ----- From: "Pawan Singh" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, April 19, 2004 1:48 AM
Subject: [WinPcap-users] Winpcap 3.1 beta: Problem with packet length and
captured length
Hi,Ethernet
I am using winpcap 3.1 beta. I am seeing IP packets on an 100 Mbitsegment which have IP header total length > 2000. This causes Winpcap
library to return packet length and captured length to be greater equal to
IP total length + Ethernet header length.
Is this a bug in winpcap because captured length should never be greater
than 1536 on an Ethernet segment? In such a case, how does the driver even
return these extra bytes (i.e. after 1536) because Ethernet card should
never provide a packet data more than 1536 bytes.
Thanks Pawan Singh [EMAIL PROTECTED]
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