Return-path: Received: from packetmixer.de ([79.140.42.25]:55902 "EHLO mail.mail.packetmixer.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750765AbdEPMFC (ORCPT ); Tue, 16 May 2017 08:05:02 -0400 From: Simon Wunderlich To: Bastian Bittorf Cc: johannes@sipsolutions.net, linux-wireless@vger.kernel.org, benjamin@sipsolutions.net Subject: Re: [PATCH 0/7] extend mac80211 mesh DFS and CSA functionality Date: Tue, 16 May 2017 14:04:58 +0200 Message-ID: <1769212.Lb3ncQ3XiW@prime> (sfid-20170516_140505_785228_41B49E55) In-Reply-To: <20170516115546.GZ18518@medion.lan> References: <20170516092316.15636-1-sw@simonwunderlich.de> <4020776.cO0ANP896r@prime> <20170516115546.GZ18518@medion.lan> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2150044.bgWHYhYXW0"; micalg="pgp-sha512"; protocol="application/pgp-signature" Sender: linux-wireless-owner@vger.kernel.org List-ID: --nextPart2150044.bgWHYhYXW0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" On Tuesday, May 16, 2017 1:55:46 PM CEST Bastian Bittorf wrote: > * Simon Wunderlich [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 --nextPart2150044.bgWHYhYXW0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE1ilQI7G+y+fdhnrfoSvjmEKSnqEFAlka6uoACgkQoSvjmEKS nqFNzxAAxEhjW9tVzQg/OXxDcXrFBeZwnBltFI5k3Wrlt3PyqYMEFzG8YHskxJ+F LnS8qD5tW4i9tRUXzRLkMBMat0ot6+y/BwYMY+uUyy38s52gIu3qPqzYq4Yj/qaX DbHUoZIYCB2KbUqRwWc8j8e/5/33BTfXdXWsWJnJWzYXhr2+5Bmg22cYxneqet/n ogJVt15hbWamNxEoHmhEZZHWmRVB/nfvAIP6xAkA1E52ng0sJmA4B5regbP9zJPu y9SE73/e927OsP/zKhxLSyLIaqj7DImBiam0ekI6tQ5nZ/PAwiUiP2eINHAHHnrk n0c9vbpEvpOoXgh7XLj7T+plC9nzJv0u/z6eq7+4V507xKtiJirvdm2JMPtcG/HJ x3M0bXv7g6BDwORA27cu8s74LMck/j+4EbzU52clo/0JtQaqCn6Os95npYhzx62F uaxrI2UpvjZ6K99vwK4uEqqpyBUA/EKfA1GCGqGdIbg+lSgKcJZeZkDACLxD3daY e+CKQXE72+k/OvwO5DrVJoPdKcJcbEtM8IymjrepQ9A/uQjwaopizan14hp6Xpad EZA9esFFPdMoW/59XELBpJtwt/o3uj5UwEe1Aq9pMhXCMGBkilQ/nWkO8lHt/hgx yEFIYItq2Mfrt1CK0ouQWSIPEf2DMa3iSN2dEN8O5K7m8PH18uc= =xA8c -----END PGP SIGNATURE----- --nextPart2150044.bgWHYhYXW0--