Missing WME information element causes problems with 802.11n

[Sam Leffler]

Alexander Egorenkov wrote:
> I have encountered a problem with a 802.11n router Belkin F5D8631au.
> The beacon and association response frames sent by this router do not
> contain
> WME information element although 802.11n mode is enabled. These frames
> contain
> HT capability IE and HT info. Because WME IE is missing in association
> responses,
> the net80211 stack does not set IEEE80211_NODE_QOS flag
> (See ieee80211_sta.c:sta_recv_mgmt:IEEE80211_FC0_SUBTYPE_ASSOC_RESP).
> But the flag IEEE80211_NODE_HT is set because the frame contains HT
> capability and HT info.
> 
> So, because IEEE80211_NODE_QOS is not set, all outgoing DATA frames sent to
> the Belkin AP
> do not contain QoS field in the 802.11 frame header. And it causes problems
> with the Belkin AP.
> 
> Is the QoS not mandatory for 802.11n mode ?
> Why is QoS enabled only if an WME IE is found in association response ?
> Would it be not right to enable QoS also if HT mode is enabled but no WME IE
> was found ?

The WME ie is mandatory; these routers are non compliant.  We can 
probably hack net80211 to auto-enable WME if an HTCAP ie is present but 
that is a total hack.  Were the HT ie's using the IEEE codes or the 
Vendor OUI codes?  It could be this is old Broadcom code--at one point 
Broadcom intentionally didn't advertise WME.  If this is the legacy HT 
stuff then perhaps we can add the auto-enable conditional on the legacy 
HT support.

	Sam