Ethereal-users: RE: [Ethereal-users] RE: q-in-q

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From: "Tiernan, Dan" <dtiernan@xxxxxxx>
Date: Fri, 10 Dec 2004 19:43:00 -0500
So are you saying it a driver issue and / or Microsoft. How do I solve or
isolate this problem.

help

Dan Tiernan
Pre-Sales Technical Support & Training
MRV Communications, Inc.
Cell      603-440-5704
Office   978-952-5846
E-mail  dtiernan@xxxxxxx
 

-----Original Message-----
From: Guy Harris [mailto:gharris@xxxxxxxxx] 
Sent: Friday, December 10, 2004 2:19 PM
To: Ethereal user support
Subject: Re: [Ethereal-users] RE: q-in-q

Tiernan, Dan wrote:

> I and a colleague are using ethereal 10.4 and wincap 2.3. My colleague 
> can capture and display a q-in-q vlan packet. *See below. *Basically, 
> the metro providers will carry customers tagged vlan traffic and append 
> another VLAN ID header to the original packet, thus reduce the 
> consumption of VLAN ID's in the metro Ethernet network.  
> 
> When I capture the same traffic, all I see is the VLAN ID from the 
> customer (vlan_10) and not Q-IN-Q vlan ID of 1000. 
> 
> Why would I have this problem? I would think that your stack is grabbing 
> the packet off the wire, so is it possible that the my nic card is 
> discriminating the q-in-q id?

It's not our stack, if "we" are the Ethereal developers - it's 
Microsoft's, the NIC driver vendor's, and the Polito di Torino's stack, 
and most of it is the NIC driver vendor's and Microsoft's; by the time 
the packet gets to the WinPcap driver (that's the Polito di Torino's 
part), the damage has probably already been done.

The WinPcap driver gets the packet from NDIS; that isn't necessarily 
what comes from the wire - the NIC, the NIC driver, or what VLAN code 
there is in Windows might be stripping off VLAN headers if you're 
capturing on a "virtual device" connected to the VLAN rather than on 
some "raw" device corresponding directly to the NIC:

	http://www.ethereal.com/faq#q5.36

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