Non-standard WDS format causes problems with non-WDS packets

Jouni Malinen jkmaline
Tue Apr 29 20:59:07 PDT 2003

On Tue, Apr 22, 2003 at 02:24:01AM +0200, Milan Krcmar wrote:

> All packets originated from computers connected to the wired side of Edimax
> are sent as stadndard-compliant 4 adress WDS frames (both FromDS and ToDS
> bits set). _But_ packets generated in the Edimax itself (it has a simple
> IP stack, ie you can ping it) are sent as common client packets (no 4th
> address information, only ToDS set). If I register Edimax's MAC as an WDS
> link, the function hostap_rx_frame_wds() recognizes theese packets as having
> non-standard WDS format (only ToDS set and address 2 in list of known WDSs),
> later in hostap_rx_skb() it is processed this way (last 6 bytes of payload
> treated as Ethernet source address).

This should now be fixed in CVS version of Host AP driver. I assume that
3-addr frames from a known WDS device are not really WDS frames. In
addition to this, I added possibility to automatically add WDS links to
this kind of devices in 'AP client' mode. If autom_ap_wds is set and a
WDS frame is received from unknown transmitter, WDS link will be added

> I am not sure whether the hostap_rx_frame_wds() can be improved to distinguish
> between non-standard WDS frames and non-WDS frames. (I've read the IEEE 802.11
> only party, I am sure at least Jouni can answer it more easily).  If it can,
> please tell me the difference between them. A second solution would be to
> optionally disable recognition of non-standard WDS frames, could be done as an
> additional bit position in "prism2_param wds_type". I could do it, if you want.

I do not think that non-standard WDS frames can be distinguished from
normal ToDS frames in generic case. However, non-standard WDS format is
needed only in Host AP mode since Managed mode is able to send
standard-compliant WDS frames. In other words, no associated STA should
be sending non-standard WDS frames; hence the fix mentioned above. This
should not even need any additional configuration.

Jouni Malinen                                            PGP id EFC895FA

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