[PATCH v2 12/12] mesh: use deterministic channel on channel switch

[Jouni Malinen]

On Tue, Jun 30, 2020 at 02:19:07PM +0200, Markus Theil wrote:
> This patch uses a deterministic channel on DFS channel switch
> in mesh networks. Otherwise, when switching to a usable but not
> available channel, no CSA can be sent and a random channel is choosen
> without notification of other nodes. It is then quite likely, that
> the mesh network gets disconnected.
> 
> Fix this by using a deterministic number, based on the sha256 hash
> of the mesh ID, in order to use at least a different number in each
> mesh network.

How would this meet DFS requirements for random/even channel selection?
And how would this interoperate with other implementations?

I'm not convinced use of a deterministic channel is appropriate for
this. The channel should still be picked randomly, but there would be
need to coordinate this throughout the mesh somehow. For example, pick a
DFS owner like in IBSS or provide means for somehow negotiating which
randomly selected channel is used (but that may be quite challenging if
there is no shared channel available for sending frames anymore).

-- 
Jouni Malinen                                            PGP id EFC895FA