setting the bit rate

[Jim Carter]

On Fri, 9 Aug 2002, Jones MB wrote:
> I have changed the driver from 12b to 11b.  I still have the same
> problem - bit rate stuck at 2Mbps.  Any idea why?

You have an Agere Orinoco card (what firmware version?) talking to an
Airport card (ditto) in Ad-Hoc mode.  I had a similar experience to yours,
with Agere firmware 6.16 fighting with a Linksys WPC11 (Intersil firmware
1.0.3 if I remember right).  Both cards worked perfectly with Cisco-Aironet
AP's at work.  But talking to each other, they would get asymmetric low
data rates: Agere->Intersil only 25 Kbytes/sec; Intersil->Agere 100 to 150
Kbytes/sec.  And the Agere card would lock into a data rate of 2 Mbit/sec,
though the Intersil (Linksys) card would report 11 Mbit/sec which was a
lie.

Another person had the same problem plus a network sniffer, and reported
that the Intersil firmware was failing to send 802.11b-level ACKs.  That
would explain the symptoms, including the data rates, quantitatively.  The
finger of blame seems to point at Intersil.  It's been pointed out that
both Ad-Hoc modes are less thoroughly tested than Managed mode (with AP's),
so subtle bugs and failure to interoperate are more likely.

Having paid my dues debugging this mess, I opened my wallet and bought an
Agere AP-200 access point for US$ 160.  My setup is now fully operational.

You are using IBSS (official) Ad-Hoc mode, aren't you, rather than Ad-Hoc
Demo mode, which was a deprecated kludge to debug the hardware and make a
few initial sales.

Hope this helps.

James F. Carter          Voice 310 825 2897    FAX 310 206 6673
UCLA-Mathnet;  6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA  90095-1555
Email: jimc at math.ucla.edu    http://www.math.ucla.edu/~jimc (q.v. for PGP key)