Wireshark · Ethereal-users: Re: [Ethereal-users] problem with vlan tags

[Guy Harris <gharris@xxxxxxxxx>]

Scott Lowrey wrote:

> Closer examination of both the driver code (in this case, the e1000 
> driver for the Intel PRO/1000 NIC) and the Linux VLAN kernel module 
> reveals that there is support in firmware for handling tags at a low 
> level - possibly before they get to the pcap library.  We're thinking 
> that when a newly-created VLAN device is created in the kernel (by the 
> ifconfig or ip commands), that device registers with the underlying 
> driver and then the driver tweaks the EEPROM parameters in the NIC to 
> strip tags, knowing that some logical frame-to-device connection will 
> have already been made.
>
> If this is correct, then it may be possible to reconfigure the driver 
> (or the 8021q module) to say, "Give me the tags anyway."

That's true of the Windows driver, apparently:

	http://support.intel.com/support/network/sb/CS-005897.htm