From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Baker Subject: Re: [PATCHv2] bridge: disable snooping if there is no querier Date: Fri, 26 Jul 2013 23:19:00 +0100 Message-ID: <51F2F5D4.50409@baker-net.org.uk> References: <1374757046-12463-1-git-send-email-linus.luessing@web.de> <1374760580-12920-1-git-send-email-linus.luessing@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: bridge@lists.linux-foundation.org, Stephen Hemminger , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Herbert Xu , Cong Wang To: =?UTF-8?B?TGludXMgTMO8c3Npbmc=?= Return-path: In-Reply-To: <1374760580-12920-1-git-send-email-linus.luessing@web.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 25/07/13 14:56, Linus L=C3=BCssing wrote: > If there is no querier on a link then we won't get periodic reports a= nd > therefore won't be able to learn about multicast listeners behind por= ts, > potentially leading to lost multicast packets, especially for multica= st > listeners that joined before the creation of the bridge. > > These lost multicast packets can appear since c5c23260594 > ("bridge: Add multicast_querier toggle and disable queries by default= ") > in particular. > > With this patch we are flooding multicast packets if our querier is > disabled and if we didn't detect any other querier. > > A grace period of the Maximum Response Delay of the querier is added = to > give multicast responses enough time to arrive and to be learned from > before disabling the flooding behaviour again. > > Signed-off-by: Linus L=C3=BCssing If the lack of queries if there is no other querier is unacceptable to=20 the majority of users (and I believe it is) then surely the sensible=20 option is to have the multicast querier toggle enabled by default. The toggle was added in the first place because the queries were=20 reported to be generating issues with certain other equipment. This may= =20 have been because the queries by default have an invalid IP address=20 (although I have been unable to identify what equipment they caused=20 problems with so can't verify this). If the only reason to turn the querier off is because it interferes wit= h=20 other equipment then the solution to it being off by default isn't to=20 generate queries in some instances even if it is off but rather to turn= =20 it on by default and only turn it off if it causes problems. If=20 multicast_query_use_ifaddr was also enabled by default the the=20 likelihood of the querier causing problems elsewhere should be reduced. Regards Adam