Subject: Re: adding an 802.11 data link type
To: None <>
From: David Young <>
List: tech-net
Date: 08/05/2002 01:09:28
On Mon, Aug 05, 2002 at 02:54:06PM +0900, Atsushi Onoe wrote:
> David Young wrote:
> >  0) DLTs DLT_802_11, DLT_PRISM_802_11, DLT_AIRONET_802_11 are desirable
> >     in addition to DLT_EN10MB.
> I think it would be better if we define DLT_DRVSPEC for all driver specific
> raw format, since I don't want to implement DLT_AIRONET_ for 'wi' driver.

How will a bpf listener distinguish Aironet's DLT_DRVSPEC from Prism's
DLT_DRVSPEC? Only driver 'an' should implement DLT_AIRONET_. Only driver
'wi' will implement DLT_PRISM_, and only when it drives a Prism NIC.

> Since the number of supported DLTs for a driver would be limited,
> multiple calls to bpfattach_dlt() may be accepted.
> This would help to implement streight forward implementation which splits
> bpf_if for each DLT.


> >  3) Two new ioctl's list/choose the DLT used by bpf:
> > 
> >       BIOCGDLTS -- returns a bit vector. "Lit" bits indicate supported DLTs.
> >                    For example, on an 802.11 interface, the DLT_EN10MB'th
> >                    bit and the DLT_802_11'th bit will be set.
> It seems that the range of the value for DLT is not defined. BIOCGDLT
> just uses u_int to pass it.  So returning array of supported DLTs would
> be better.


> > If this is not substantially how people desire for the 802.11 DLT to work,
> > let me know.
> > 
> > If somebody has already begun to program this feature, stop me.
> I'll search the code once I've implemented from my backups.

Let me know what you find out.


David Young             OJC Technologies     Engineering from the Right Brain
                        Urbana, IL * (217) 278-3933