Return-path: Received: from mail-ot0-f170.google.com ([74.125.82.170]:33157 "EHLO mail-ot0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754257AbdCFWdX (ORCPT ); Mon, 6 Mar 2017 17:33:23 -0500 Received: by mail-ot0-f170.google.com with SMTP id 19so52982405oti.0 for ; Mon, 06 Mar 2017 14:32:05 -0800 (PST) From: Jesse Jones References: <58B09082.7020704@cococorp.com> (sfid-20170224_205905_277542_E6C0402D) <1488202227.28431.9.camel@sipsolutions.net> <58B487A8.7000602@cococorp.com> (sfid-20170227_211019_763670_B9D8D712) <1488443814.8390.3.camel@sipsolutions.net> (sfid-20170302_184150_751594_B059708D) <1488803913.5761.11.camel@sipsolutions.net> In-Reply-To: <1488803913.5761.11.camel@sipsolutions.net> MIME-Version: 1.0 Date: Mon, 6 Mar 2017 10:01:00 -0800 Message-ID: (sfid-20170306_233340_727302_56218F29) Subject: RE: [PATCH v2] mac80211: Jitter HWMP MPATH reply frames to reduce collision on dense networks. To: Johannes Berg , agreen@cococorp.com, linux-wireless@vger.kernel.org Cc: Jesse Jones Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: > > Well it certainly attempts to via stuff like carrier sense. But that > > is not fool proof and any time two routers hear a frame and both > > decide to forward it immediately there is a chance that they will both > > sense the air at the same time, decide that it is clear, and lose both > > their forwarded frames due to a collision. How often that happens is > > hard to say but we have observed that exact behavior a few years ago > > with an 802.11 multicast routing protocol and adding jitter > > significantly improved reliability. > > I'm really surprised by this since they both should jitter their > transmissions > already between CWmin and CWmax. Is that window somehow really super > small for what you're doing? I don't think so. -- Jesse