On 2024/02/16 10:13, Stefan Sperling wrote:
> Tne driver uses the lowest basic rate anncounced by the AP:
>
> const struct iwx_rate *
> iwx_tx_fill_cmd(struct iwx_softc *sc, struct iwx_node *in,
> struct ieee80211_frame *wh, uint16_t *flags, uint32_t *rate_n_flags)
> {
> [...]
> int min_ridx = iwx_rval2ridx(ieee80211_min_basic_rate(ic));
>
> This rate will be used for broadcast frames, which include DHCP requests.
..so one reason to disable lower rates might be on networks with higher
expected levels of broadcast(/multicast)
> One reason to keep 6 Mbps disabled would be many APs on the same channel,
> so many that their collective beacons sent at 6 Mbps use up all available
> air time, leaving no time for actual data. But unless you're running something
> like a CCC congress this limitation won't apply ;)
Besides the airtime saving in very dense environments, another reason
would be in a less dense environment (but still with multiple APs on the
same channel), to discourage STAs from remaining associated with a more
distant AP - say a STA is right at the edge of range of an AP, but near
another AP on the same channel - even if the first AP's transmissions
don't cause co-channel interference (say, the power is fairly low to
avoid this), the *STA's* transmissions can do.
So probably not so useful on a typical home setup where you'd usually
have no more than a coupke of APs and none co-channel, it could make
sense for say a medium-density office environment (especially on 2GHz).
https://divdyn.com/disable-lower-legacy-data-rates/ seems quite a good
write-up.
Also: regardless of whether it really makes sense for a given network,
sometimes a network operator will do this anyway and as a user you have
no control over it - and based on Kirill's description this seems a
regression since 7.4?
