Am 21.09.2017 um 15:52 schrieb Johannes Berg:
On Fri, 2017-09-08 at 18:07 +0200, Richard Schütz wrote:
Use IEEE80211_RATE_MANDATORY_G instead of IEEE80211_RATE_MANDATORY_B
to get
all mandatory rates in 2.4 GHz band. It is safe to do so because ERP
mandatory rates are a superset of HR/DSSS mandatory rates. Also limit
to
OFDM rates for 10 MHz and 5 MHz channels as originally intended by
commit
74608aca4d82e.
I don't understand this. Why should all ERP (Clause 18, 11g) rates be
mandatory for the users of this?
The way I see it, this would make us assume that all 2.4 GHz clients
support ERP in IBSS, which may not be true?
I disagree. On a HR/DSSS PHY this would still only return HR/DSSS rates
because there should not by any ERP rates present in sband->bitrates in
the first place.
The reason for suggesting this change is that the basic rate set for a
mesh STA is initialized with this function if not explicitly configured
beforehand.
IEEE Std 802.11-2016 (10.7.4 Basic rate set, basic HT-MCS set, and basic
VHT-MCS and NSS set for mesh STA) states: A mesh STA shall not establish
a mesh peering with a mesh STA using a different BSSBasicRateSet (see
14.2.7 and 14.2.8). The SME of a Mesh STA should use the mandatory PHY
rates as the default BSSBasicRateSet in the MLME-START.request primitive
to reduce the risk that a candidate peer mesh STA utilizes a different
BSSBasicRateSet.
Selecting only HR/DSSS mandatory rates for a mesh STA default basic rate
set on an ERP PHY violates this requirement in my opinion.
wpa_supplicant explicitly configures all ERP mandatory rates for ERP
mesh points in its default configuration, whereas iw relies on the
kernel to do the selection. This currently leaves us with the
unfortunate situation that you can not join such a mesh BSS created by
wpa_supplicant using iw without further configuration and the other way
round.
--
Richard
