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Re: DHCP failing due to missing VLAN tagging support


On Mon, Oct 27, 2008 at 10:16:25PM +0100, ?yvind Harboe wrote:
> I got some feedback today on the FreeBSD stack that DHCP fails
> because it does not support VLAN tagging. "older devices do not
> necessarily support VLAN tagging" was what I heard...
> 
> The fallback is to use static IP address for this case, which isn't pretty
> but it gets the job done.

This makes little sense to me. VLAN tagging, also known as 802.1q,
adds a 4 byte header between the ethernet MAC addresses and the frame
type field. Using this header you can say that a frame belongs to one
of 4096 virtual LANS. You would then have a DHCP server on the virtual
LAN, or multiple DHCP servers on multiple VLANs.

The eCos FreeBSD stack has no support for VLANs what so ever. So
adding a static IP address would not help. The frames would still not
have a VLAN tag. 

I suggest you go back to your customer and ask for more details. Your
customer seems confused, which is not uncommon.

         Andrew

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