[OpenWrt-Devel] Multiple OpenWrt devices collectively managed?

Janne Cederberg janne.cederberg at gmail.com
Mon Mar 23 16:25:32 EDT 2015

Cool, this sparked a conversation :)
Yes, the background of the question was not a mesh network but a
network where all APs could be connected to the same switch for
example and from there to a DHCP server. A controller would control
which channels the APs operate on to minimize interference a) from
each other and b) from possible other networks. David Lang stated
exactly what I was attempting to convey.

So there's the auto mode in OpenWrt but that only considers the state
of the wifi spectrum at the ifup of the wifi adapter, correct? So if
things drastically change later, the AP would stay on the same channel
and not switch.

I haven't used but understood that for example Cisco enterprice APs
can be controller-managed and the controller can tell an individual or
multiple APs to switch channels to actively avoid "bad" channels. What
ideas the switch algorithm actually is based upon/using I personally
have no clue of atm. Just started looking into the issue a few days

Personally I'm familiar and semi-fluent with Ansible, used it in one
project so far.

I was thinking the same thing David mentioned, namely, that
determining channel change criterion is probably not trivial. Are you
guys familiar with Cisco Meraki?


2015-03-23 21:45 GMT+02:00 David Lang <david at lang.hm>:
> On Mon, 23 Mar 2015, Bastian Bittorf wrote:
>> * David Lang <david at lang.hm> [23.03.2015 20:19]:
>>> question is around having something to automatically assign channels
>>> amoung the different APs to minimize interference between the APs and
>>> between the APs and other things in the area.
>> we just use hostapd & athXk & acs-survey/channel=auto...why dont you?
> For one thing I hadn't heard of it before now :-)
> I would need to test and see what it recommends in real-world conditions. It
> seems designed for setting up a single AP (although it really shouldn't try
> every 2.4GHz channel), but when trying to pick channels for a bunch of APs
> in an area, I see nothing in the documentation that would prevent every AP
> from picking the same channel because it was marginally better when
> everything is quiet.
> Then when you start to see heavy usage, the situaion will have changed
> drastically and you would have to take time away from servicing clients to
> scan other channels (during which time you are not transmitting normally, so
> any other APs doing a survey during the same time would get a faulty view of
> what the conditions are), and would the system converge to a stable setup,
> or would it always be shifting traffic.
> David Lang
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