From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=OgPj8P++ZhLQ+47ER+bIDyoC8972Pe7h96HpMP/idLw=; b=3FI0+SMSp+O/2amFlgHp893dQF451jYCFmePkzMWjKAaHNOvrMw4yYNcTgTM7f4Le73tSV7c6ifjurHDtbqOUtr2SYFUJ7XnLBescSwBjioREG5dyCSrgzthz3INDLHxNoEVsx1zr6h5bHg3p4i4kLmz1DyiHlJulxFs3iQ9tdU=; Date: Fri, 11 Jan 2019 16:43:31 +0100 From: Andrew Lunn Message-ID: <20190111154331.GE20924@lunn.ch> References: <20190110193206.9872-1-f.fainelli@gmail.com> <20190111150637.GA897@splinter.mtl.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190111150637.GA897@splinter.mtl.com> Subject: Re: [Bridge] [PATCH net-next v4] Documentation: networking: Clarify switchdev devices behavior List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ido Schimmel Cc: Florian Fainelli , "ivan.khoronzhuk@linaro.org" , "nikolay@cumulusnetworks.com" , "netdev@vger.kernel.org" , "roopa@cumulusnetworks.com" , "bridge@lists.linux-foundation.org" , "vivien.didelot@gmail.com" , Jiri Pirko , "ilias.apalodimas@linaro.org" , "rdunlap@infradead.org" , "davem@davemloft.net" > > +IGMP snooping > > +~~~~~~~~~~~~~ > > + > > +The Linux bridge allows the configuration of IGMP snooping (compile and run > > +time) which must be observed by the underlying switchdev network device/hardware > > +in the following way: > > + > > +- when IGMP snooping is turned off, multicast traffic must be flooded to all > > + switch ports within the same broadcast domain. The CPU/management port > > + should ideally not be flooded and continue to learn multicast traffic through > > + the network stack notifications. If the hardware is not capable of doing that > > + then the CPU/management port must also be flooded and multicast filtering > > + happens in software. > > + > > +- when IGMP snooping is turned on, multicast traffic must selectively flow > > + to the appropriate network ports (including CPU/management port) and not flood > > + the switch. > > + > > +Note: reserved multicast addresses (e.g.: BPDUs) as well as Local Network > > +Control block (224.0.0.0 - 224.0.0.255) do not require IGMP and should always > > +be flooded. > > I'm not sure that these paragraphs are actually needed. You're basically > describing RFC 4541 on which the IGMP snooping functionality in the > Linux bridge is based on. Hi Ido My experience talking with people is that IGMP snooping is a bit mystical and not well understood. I would not be surprised if community driver writers, as opposed to vendor driver writers, don't actually know how snooping works. So i find having some hints is good. Andrew From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lunn Subject: Re: [PATCH net-next v4] Documentation: networking: Clarify switchdev devices behavior Date: Fri, 11 Jan 2019 16:43:31 +0100 Message-ID: <20190111154331.GE20924@lunn.ch> References: <20190110193206.9872-1-f.fainelli@gmail.com> <20190111150637.GA897@splinter.mtl.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Florian Fainelli , "netdev@vger.kernel.org" , "davem@davemloft.net" , "vivien.didelot@gmail.com" , "cphealy@gmail.com" , Jiri Pirko , "bridge@lists.linux-foundation.org" , "nikolay@cumulusnetworks.com" , "roopa@cumulusnetworks.com" , "rdunlap@infradead.org" , "ilias.apalodimas@linaro.org" , "ivan.khoronzhuk@linaro.org" To: Ido Schimmel Return-path: Received: from vps0.lunn.ch ([185.16.172.187]:40456 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728632AbfAKPng (ORCPT ); Fri, 11 Jan 2019 10:43:36 -0500 Content-Disposition: inline In-Reply-To: <20190111150637.GA897@splinter.mtl.com> Sender: netdev-owner@vger.kernel.org List-ID: > > +IGMP snooping > > +~~~~~~~~~~~~~ > > + > > +The Linux bridge allows the configuration of IGMP snooping (compile and run > > +time) which must be observed by the underlying switchdev network device/hardware > > +in the following way: > > + > > +- when IGMP snooping is turned off, multicast traffic must be flooded to all > > + switch ports within the same broadcast domain. The CPU/management port > > + should ideally not be flooded and continue to learn multicast traffic through > > + the network stack notifications. If the hardware is not capable of doing that > > + then the CPU/management port must also be flooded and multicast filtering > > + happens in software. > > + > > +- when IGMP snooping is turned on, multicast traffic must selectively flow > > + to the appropriate network ports (including CPU/management port) and not flood > > + the switch. > > + > > +Note: reserved multicast addresses (e.g.: BPDUs) as well as Local Network > > +Control block (224.0.0.0 - 224.0.0.255) do not require IGMP and should always > > +be flooded. > > I'm not sure that these paragraphs are actually needed. You're basically > describing RFC 4541 on which the IGMP snooping functionality in the > Linux bridge is based on. Hi Ido My experience talking with people is that IGMP snooping is a bit mystical and not well understood. I would not be surprised if community driver writers, as opposed to vendor driver writers, don't actually know how snooping works. So i find having some hints is good. Andrew