Re: WDS ping

From: Jim Thompson (
Date: 2002-03-03 09:20:04 UTC

I'd love to look at the code. Routing isn't *always* possible.


Kristian Hoffmann writes:
> We (a collegue and myself) modified the linux-wlan-ng driver to support
> 802.11b compliant WDS. It doesn't work. The firmware/card silently drops
> the transmit frames without generating a TxExc. Intersil's response for
> us was something like, "Yes it's broken and it might get fixed, kinda,
> maybe, probably not." In frustration, we wrote a non-standard WDS
> implementation using a "magic" mac address in the A3 header field of
> 00:00:de:ad:be:ef. At least I'm pretty sure it was the A3 field.
> Anyway, the driver would check for that mac address and if found, ignore
> the dest mac address in the 802.11 header and reconstruct the 802.3 frame
> from the payload only. The easiest way to do that was just force the
> "encapsulation" encoding method on all WDS stations' transmitted frames.
> Realizing that was a horrible kluge, we decided on a lesser kluge. We
> setup a proc configurable list of mac addresses to check for instead of
> the magic 00:00:de:ad:be:ef. So in that case, you just add the mac
> address for any "WDS" stations. Then when the AP receives a frame from a
> station in the list, it assumes it's an encapsulated frame and ignores the
> dest address on the 802.11 frame and netif_rx's the encapsulated frame
> instead of attempting to reconstruct the header.
> The scariest part was that both ways worked. Only we ran into interesting
> problems with broadcast frames but that would take a lot of explaining.
> If anyone isn't scared out of their mind and wants to look at the code,
> I'll post a link. We stopped without working out all the bugs and
> cleaning up the interface because I LEARNED HOW TO ROUTE and stop bridging
> like a wuss. Sorry, I had to. We realized we were going through all this
> trouble to avoid routing. It's not worth it so get over it. :P
> Kristian Hoffmann
> PC-InTOUCH/FireToWire System Administrator
> ---
> On Fri, 1 Mar 2002, Jerritt Collord wrote:
> >
> > Well it's been a while since anyone mentioned this, so I'll
> > venture out cautiously... what's up with WDS implementations for
> > HostAP?
> >
> > OpenAP came out and there looked to be interest and work towards
> > implementing their system, but concerns arose that it broke
> > 802.11 spec.
> >
> > Jim Thompson questioned the Prism2 firmware support for WDS...
> > zero threadage on that.
> >
> > Thanks,
> >
> > Jerritt Collord
> >
> >

"Life begins when you can spend your spare time programming
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