Host Ap Tuning

lists lists
Fri Nov 29 14:04:19 PST 2002

I am working on switching our lucent AP based WISP systems over to
hostap/linux, and have started seeing odd contrasts between the two
architectures.  Hostap works very well in a test environment, showing
speeds at or exceeding that of the lucent hardware.  When used in ranged
situations, with customers from .5 to 5 miles away, the hostap unit does
not perform nearly as well.  In trying to trace down the cause, we have
tested a number of variables including rts limit, frag limit (which
appears to not work), beacon time, dtim time, and rate control.  None of
these had a significant effect on throughput.  The signals are strong as
read by the card, and we see a lot of errors at the driver level.  The
interface registers about 18360 'invalid misc' errors an hour, and about
2041 excessive retries an hour.  The following message also shows up
from the kernel at several per minute:

wlan0: TXEXC - fid=0x0144 - status=0x0001 ([RetryErr]) tx_control=000c
   retry_count=0 tx_rate=55 fc=0x0a08 (Data::0 FromDS)
   A1=00:02:2d:1e:22:a0 A2=00:02:6f:01:d2:62 A3=00:02:6f:01:d2:62

The questions i have are 1)  How do the rts and frag thresholds work in
hostap, and do they have an effect on performance when scaling from few
to many clients;  2)  what causes the 'invalid misc' errors and should
the figure be used as a indicator for overall performance of the driver;
and 3)  are there certain variables that should be concentrated on when
trying to tune the ap for medium to long range WISP use?

Thanks in advance for your help,

WiNet, Inc.
Columbus, OH

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