Re: [Make-wifi-fast] mesh deployment with ath9k driver changes

[Sebastian Moeller <moeller0@gmx.de>]

Hi Pete,

being ignorant on how one sets up a p2p bwifi backbone, I wonder wherher qos-maps might be useful to effectively disable WMMon a link without remapping the dscp field or tunneling the enduser IP psackets? See https://patchwork.kernel.org/patch/3212651/ and hostapd.conf:

# QoS Map Set configuration
#
# Comma delimited QoS Map Set in decimal values
# (see IEEE Std 802.11-2012, 8.4.2.97)
# 
# format:
# [<DSCP Exceptions[DSCP,UP]>,]<UP 0 range[low,high]>,...<UP 7 range[low,high]>
# 
# There can be up to 21 optional DSCP Exceptions which are pairs of DSCP Value
# (0..63 or 255) and User Priority (0..7). This is followed by eight DSCP Range
# descriptions with DSCP Low Value and DSCP High Value pairs (0..63 or 255) for
# each UP starting from 0. If both low and high value are set to 255, the
# corresponding UP is not used.
# 
# default: not set
#qos_map_set=53,2,22,6,8,15,0,7,255,255,16,31,32,39,255,255,40,47,255,255

You could simply use
qos_map_set=0,63,255,255,255,255,255,255,255,255,255,255,255,255,255,255
to map all dscps to UP0...

I have not played with this feature though, so it might not work at all for your purpose.

Best Regards
	Sebastian



> On Jul 9, 2018, at 08:27, Pete Heist <pete@heistp.net> wrote:
> 
> 
>> On Jul 9, 2018, at 7:17 AM, Jonathan Morton <chromatix99@gmail.com> wrote:
>> 
>>> On 9 Jul, 2018, at 5:20 am, Aaron Wood <woody77@gmail.com> wrote:
>>> 
>>> Do the AP-to-AP links use the same packet scheduling as the AP-to-STA links? (especially the prohibition on aggregation for VO, which seems counter-productive on a backhaul link).
>> 
>> I believe they do, since they go through the same type of MAC grant process.  To avoid that, the AP would need to ignore the traffic class when assigning backhaul packets to queues.
> 
> I’m also almost sure of that. However, since I set all DSCP values to 0 in PREROUTING, most traffic going over the backhauls is now best effort, and I haven’t been able to detect a change in ping times to the APs. The change was made July 5 around 10am and, for example, this is probably our most challenged AP: https://www.drhleny.cz/smokeping/Cabin12.html
> 
> I still think making backhaul traffic best effort makes sense. In my point-to-point tests, I sometimes do this using IPIP tunnels, so the DSCP value of the inner packet is hidden from the WiFi stack, but the value is still maintained after it passes through the tunnel. A drawback of this is that the MTU is shortened by 20 bytes.
> 
> Tomorrow I’ll be setting up a 5GHz point-to-point backhaul link for Cabin 28 (higher standard cabins), so I expect a significant change there.
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