Asymmetry in performance using orinoco_cs

[Jim Carter]

On Wed, 5 Jun 2002, Tom Balon wrote:
> I'm running a Suse 7.3 kernel with the orinoco_cs.o
> driver (rel 0.10) and a Orinoco Silver radio card. It
> is acting as my firewall/gateway to the Internet
> connecting an ISP's Cisco AP offering a 2Mbs
> connection.
--- paraphrase: ---
200 Kbyte/sec Cisco AP to Orinoco (almost full speed on 2Mbit/sec link)
30-34 Kby/sec Orinoco to Cisco AP.

Between a Dell Truemobile 1150 mini-PCI card (by Agere, with Lucent-Agere
firmware v6.16) and a Linksys WPC11 PCMCIA card (Intersil firmware v1.03),
operating in Ad-Hoc mode, I get 20-25 Kby/sec speed, Dell to Linksys, but
much faster in the opposite direction. Similar behavior has been seen by
another person on the list, who had a wireless sniffer set up, and he was
able to prove that the Intersil card was failing to ack the data packets.
This results in multiple retries and attempts to fall back to lower speeds
(1 Mbit/sec), which take a lot of time. On download, the TCP/IP acks also
are not 802.11b acked, but they're much shorter, so the data transfer is
slowed down by only 20-30%.

It's currently attributed to a bug in the Intersil firmware, specifically
the Ad-Hoc support. When I communicate with a Cisco-Aironet AP at work (I
don't know the model), I can upload and download at full speed for 802.11b.

I've tried everything, and have not been able to improve the situation. If
you get any leads or ideas for improving this behavior, I will be very
interested to see them.


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)