Re: DTIM (Power Save Mode) w/ HostAP

On Fri, Mar 07, 2003 at 12:50:05AM -0800, Matt Peterson wrote:
> A compatibility issue arose from testing BSD HostAP mode with an Intel 
> Centrino 11b client.  (Stay tuned at your favorite airport, net coffee 
> shop, etc. on March 12th for all the marketing foo on Centrino.)  When the 
> NIC in question (rumored to be a recycled Symbol MAC) has power management 
> enabled (the big selling point of Centrino silicon suite), poll requests 
> aren't processed correctly by the HostAP mode driver.  Thus, the STA keeps 
> sending re-tries (PS-Poll) to download its "buffered" data.

With Prism, a host AP is responsible for detecting that a STA has switched
to powersave mode and for queueing its packets until is PS-Polls.

The NetBSD code does not detect power-saving STAs or queue their
packets, so PS STAs will lose. Did FreeBSD add this function?

Sam Leffler has produced a mega-patch to the 802.11 framework that I
*think* contains PS queueing. Failing that, my "jumbo" patch to NetBSD
contained the beginnings of PS queueing, but it was clobbered by Atsushi
Onoe's very fine 802.11 framework.

Maybe somebody out there knows off the top of their head

1 What are the timing requirements for answering PS-Polls? Can we
  meet the requirements if the HostAP driver will not queue at least
  one PS packet per STA and hold it until until that STA's PS-Poll?

2 Will the HostAP driver actually queue and hold one PS packet?
 
Dave

-- 
David Young             OJC Technologies
[email protected]      Engineering from the Right Brain
                        Urbana, IL * (217) 278-3933
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