RTS/CTS not fully disabled?

[Jouni Malinen]

On Tue, May 22, 2007 at 12:31:14PM +0200, ahuguet at cttc.es wrote:

> > If I remember correctly, there
> > were some changes to rate control algorithm in the firmware and it may
> > have involved use of RTS/CTS in some cases. If the firmware versions are
> > different, I would assume this would be reason for the behavior you are
> > seeing.
> 
> >From what I've been able to read in the mailing list, it indeed seems to
> point to a rate control issue.
> It seems that, if the card fails for the 3rd time (IIRC) to send a packet
> (that is, doesn't receive an ACK for said packet) it tries to adapt its
> transmission rate, to the value immediately lower.

That is the default behavior in STA firmware. I looked at bit more
details on documentation and this behavior should actually be
configurable. I would assume that the cards you are using are setting
CNFFALLBACKCTRL (RID FCB5) to the default value 0x047C which is
requesting rate control algorithm to start using RTS/CTS on third retry.
I would suggest testing a value of 0x007C in that RID to prevent this
from happening.

You should be able to read the current value with 'hostap_rid wlan0 get
fcb5' and set the new value with 'hostap_rid wlan0 set fcb5 7c 00' (the
value is little endian, so swapped bytes here). Please let me know
whether this helps in your test setup.

-- 
Jouni Malinen                                            PGP id EFC895FA