ath0 timeout problem - again

Sam Leffler sam at
Sat Dec 30 12:37:30 PST 2006

JoaoBR wrote:

> 572 cabq frames transmitted
> 11 cabq xmit overflowed beacon interval

>         media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11b <hostap>

So one other thing came to mind.  If your ap is operating in 11b and you
have many multicast frames q'd up for power save stations then they can
effectively saturate the network if they are being trasnmitted at a low
tx rate (which they would be).  This can effectively DOS your wireless
network because the frames are burst immediately following the beacon.
The driver limits the burst interval so it does not overflow into the
next beacon but it's allowed to fill all available time to the next
beacon frame (something I've considered changing for just the reason I
described).  This has always been an issue.  You might try rate limiting
these frames or just hack the driver to violate the spec and not buffer
them for tx after the beacon (to see if your problem goes away).

Further, if you have  a machine with a crappy pci bus (such as !4801
soekris boards) it's entirely possible that you are hoarding the bus
with these long transmits s.t. other problems are occurring.  I do not
recommend building ap products out of such equipment.  (No disrespect to
the 4501, et al they just had substandard pci bus operation.)


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