On Tuesday, May 16, 2017 1:55:46 PM CEST Bastian Bittorf wrote: > * Simon Wunderlich <[email protected]> [16.05.2017 12:24]: > > * station A detects a Radar, and informs userspace > > * userspace of station A will initiate a CSA, kernel will execute it > > (action> > > frame, beacons) > > > > * station B picks up the CSA, and executes it as well > > * station B also marks the channel as unavailable > > * both station A and station B will send an event to userspace once the > > > > channel switch is complete > > ah, I remember the slides from last battlemesh. > > The "problems" in userspace are: we must maintain a global list > (so each node) which channel is the next best and we must time > the final channel switch. IMHO the specs are saying, that we must > switch within 30 secs after detecting the first radar-pattern. > Also we must mark/show the new channel somehow for new/crashed/upcoming > nodes. quite hard...
The timing is not a big problem, since the switch does not happen immediately
but is performed after a "countdown" which is part of the channel switch
announcement IEs. The specific rules for the countdown depend on the regulatory
domain, but it's usually something between 1 and 5 seconds where payload
traffic
must not be transmitted (at least for the DFS case).
The bigger problem appears when a node is missing the CSA for whatever reason,
or is joining the network - worst case, the mesh network can split into clouds
on different channels. This is where we need the global list, or showing the
next channel, etc. :)
Cheers,
Simon
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