Re: QoS prioritization doesn't work correctly and no QoS control fields

>> Did you enable CONFIG_IPW2200_QOS? You can dump more QoS related stuff
>> with debug=0x80000000.

Thanks, this helped to get more info. It shows that qos is enabled and
everything's ok (I did enable CONFIG_IPW2200_QOS).

Theoretically, QoS control field must ALWAYS be present in 802.11 frames for
any QoS functionality. Is this correct???

If ipw2200 debug output says that qos is enabled, but there are no QoS
control fields, it means only that the problem is with the access point. Is
this correct? (I enabled qos in my cisco AP, but I have some reasons to
believe that AP might not properly work).

I measure the traffic with some of my scripts based on 'tshark'. I also
tried to use 'pktstat', but it shows sometimes completely wrong numbers
(e.g. 100Mbps for 54Mbps wireless link). Can anyone recommend any tool for
measurements? The tool should be able to show not just the total throughput
for a interface, but also the throughput for each stream/connection. I tried
many different tools, but they all show wrong numbers for wireless
measurements (why?), so maybe anyone encountered this problem?

Thanks a million for any help!!!!!!


2008/12/10 Zhu Yi <[email protected]>

> On Mon, 2008-12-08 at 22:03 +0800, Marco Talunzo wrote:
> > Hi all,
> >
> > I'm trying to work with QoS and have some problems.
> >
> > After installation of ieee80211-1.2.18 and ipw2200-1.2.2, I see that
> > prioritization is somehow works. This is how I mark the packets (with
> > iptables):
> >
> > DSCP         AC
> > 0x08  -->  AC_BK
> > 0x00  -->  AC_BE
> > 0x28  -->  AC_VI
> > 0x30  -->  AC_VO
> >
> > With some debugging code in ipw2200.c I observe that all packets
> > correctly go to different transmission queues according to markings.
> >
> > PROBLEM 1: when I observe the throughput produced at each access
> > category I see that packets in AC_VO get transmitted with the highest
> > priority (that's fine), but there is no any difference in performance
> > between AC_VI, AC_BE and AC_BK access categories, e.g. AC_BK has the
> > same throughput as AC_VI!  (any idea why?)
>
> How did you measure throughput? What is the cw_min, cw_max and AIFS
> setting for the 4 categories in your AP?
>
> > PROBLEM 2: when I monitor the traffic I don't see any QoS control
> > field in 802.11 frames. The frames are not of "QoS data" type (see
> > below). It's strange that prioritization is somehow working (AC_VO has
> > highest throughput, for sure), but no any QoS control fields. Is this
> > possible? Do we always need a QoS control field for QoS features?
> > Don't understand how I can see prioritization without QoS control
> > field...
> >
> > IEEE 802.11
> >    Type/Subtype: Unknown (0x14)      <------ not a "QoS data" type
> >    Frame Control: 0xA045 (Normal)
> >        Version: 1
> >        Type: Control frame (1)
> >        Subtype: 4
> >        Flags: 0xA0
>
> Did you enable CONFIG_IPW2200_QOS? You can dump more QoS related stuff
> with debug=0x80000000.
>
> Thanks,
> -yi
>
>

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