Promiscuous strangeness with Prism II card + orinoco-0.11 driver

Miklos Szeredi Miklos.Szeredi at
Fri Apr 26 17:04:30 EST 2002

I'm using the orinoco-0.11 driver with an SMC-2632W card in managed
mode.  I've tested it with a Lucent AP as well as a with another
SMC-2632W card driven by the PrismII host-AP driver.

When the card is put into promiscuous mode (e.g. by starting tcpdump)
the receiving throughput drops from 4.5Mb/s to about 300kb/s.

Using a wireless sniffer I've managed to uncover the cause of this:
the card in not sending ACK's in reply to data frames, even though it
does receive them.  This will cause the AP to retransmit the data
frames many times, thus decreasing the throughput.

Has anyone experienced similar problems?

The same behavior can be observed with the wvlan_cs driver.  Only the
orinoco and the wvlan_cs driver seem to actually implement promiscuous
mode, so I cannot test this with other drivers (wlan-ng, PrismII).
Lucent cards using the same driver work normally in promiscuous mode.

The f/w version of the SMC card is reported as 0.08 by the orinoco
driver, and 0.8.3 by the PrismII driver.

Is it possible that this is a firmware bug?  Where do I report such a bug?

Any help is appreciated!


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