Orinoco Ad-Hoc under Linux (2.4.6)

David Gibson david at gibson.dropbear.id.au
Thu Aug 23 17:54:36 EST 2001

On Mon, Aug 20, 2001 at 10:54:52AM +0200, Herwig Schelauske wrote:
> Hi,
> I try to set up a Ad-Hoc wireless connection (Peer-To-Peer) with 2
> Lucent Orinoco Silver PCMCIA-Cards (Variant 1, Version 4.00, Firmware
> 4.00/7.52) under Linux between an StrongARM based board (Assabet) and my
> notebook, using original Kernel 2.4.6 Hermes/Orinoco drivers.
> If I ping from Assabet to the notebook, I receive only LLC (Logic-Link
> Control) packets at my notebook. Cause I have no tcpdump/Ethereal at the
> Assabet, I only know what I'am receiving at the Notebook.

802.11 always uses 802.2 LLC, but the driver
encapsulates/de-encapsulates the packets before presenting them to the
network layer.  From the dump below it looks like the driver on the
Assabet is inserting two extra zero bytes between the 802.2 LLC and
SNAP headers.  My guess would be that this is due to some ARM specific
alignment issue.

> Pinging from notebook to Assabet, I sending out ICMP-packets (see
> Ethereal log down, source and destination seems to be OK). ifconfig
> shows increasing RX packets at Assabet, but isn't answering (TX doesn't
> increase). Why that?

Presumably the encapsulation fault which is causing the Assabet to
send bogus packets is also causing it to not recoginize the incoming
pings as pings.

I suspect that on the ARM is aligning the dldwd_frame_hdr structure
differently from the other platforms that have been tried (mostly x86
and ppc).  That either means I've missed a ((packed)) attribute
somewhere, or there is a gcc bug which means it is not properly
honouring the ((packed)) attribute.

David Gibson			| Microsoft: Making the easy things hard
david at gibson.dropbear.id.au	| and the hard things buggy

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