QCA988X firmware 10.1 and Broadcom stations

Andy Strohman andy at uplevelsystems.com
Sat Aug 13 22:37:53 PDT 2016

Sorry, I meant to say 10.1 in the subject.  So the pings I described
break traffic with the 10.1 firmware.   I never tested 10.2, but I am
currently evaluating 10.2.4(firmware-5.bin_10.


On Fri, Aug 12, 2016 at 7:26 PM, Andy Strohman <andy at uplevelsystems.com> wrote:
> Hello,
>   I have an issue with what seems to be an interoperability problem
> between the 10.2 firmware and Broadcom stations.
>   The symptoms look similar to what you guys were discussing in the
> thread with subject:  "Unicast packets stop being transmitted to a
> particular station."
> I have two machines that can reproduce the issue consistently:
> 1)Dell Latitude E6400 with a Broadcom BCM432b / BCM32056000 chipset.
> (The Dell Wireless 1510 Wireless-N WLAN Mini-Card Rev 4.06). The
> driver version is and the date of the driver is
> 3/14/2012.
> 2)MacBook Pro (Retina, 13-inch, Early 2015).  Broadcom 4360
> All I need to do is ping the BCM station using a DSCP value that maps
> to the higher of the two tids in an AC.  After this, packets with the
> lower of the two tids will no longer be accepted, even though I see an
> ACK for the packet.
> This applies to all ACs.  So,
> ping -Q 96 stops all tid 0 traffic
> ping -Q 64 stops all tid 1 traffic
> ping -Q 160 stops all tid 4 traffic
> ping -Q 224 stops all tid 6 traffic
> I cannot get the larger of the two tids(per AC) to drop.
> Given this behavior, I think what is happening is that BCM has one PN
> counter per AC.  I noticed that 10.2 firmware appears to use one PN
> counter per tid where the most significant byte of the PN is the tid.
>  So when a packet with the larger of the two tids is transmitted from
> QCA to BCM(with it's larger most significant byte in the CCMP PN), the
> BCM counter for the whole AC gets set to this PN.   Then later, when a
> packet is received with the smaller of the two tids(with smaller MSB)
> it is dropped because BCM considers it a replay attempt.
> I see that QCA sets the RSN PTKSA Replay Counter capabilities to 16,
> while BCM sets to 1.  Although, I do not know what the expected
> outcome of this is supposed to be.  It's seems like BCM decides to use
> 4 - one per AC.  I also don't know how 8 tids are supposed to be
> mapped to 16 PN counters.  Any insight into this would be appreciated.
> I noticed with 10.2.4 that  RSN PTKSA Replay Counter capabilities is
> still set to 16.   However, instead of having a separate counter for
> each tid, there appears to be a single counter, which prevents this
> issue from consistently occurring.
> I intend to move to the 10.2.4 firmware to get away from this problem.
> However, with 10.2.4, I have witnessed problems where certain tids do
> not make it though while others do.  Unfortunately, last time it
> happened, I did not understand as much about this issue as I do now,
> so I did not test/observe as thoroughly as I wished I would have.
> Any help/insight would be much appreciated.
> Thanks,
> Andy


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