Return-path: Received: from nbd.name ([46.4.11.11]:49837 "EHLO nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754191AbdAKMVk (ORCPT ); Wed, 11 Jan 2017 07:21:40 -0500 Subject: Re: [PATCH net-next] bridge: multicast to unicast To: IgorMitsyanko , Johannes Berg , =?UTF-8?Q?Linus_L=c3=bcssing?= , Stephen Hemminger References: <20170102193214.31723-1-linus.luessing@c0d3.blue> <1483706872.4089.8.camel@sipsolutions.net> <8836daaa-9638-4502-d079-fd428595f822@nbd.name> <1483710841.12677.1.camel@sipsolutions.net> <22fad045-57c6-7789-d19f-f47bd0faf441@fami-braun.de> <20170107145516.GE3134@otheros> <1483949336.17582.3.camel@sipsolutions.net> <6f5ec9f1-800a-2bc4-2f41-9d803343bb22@fami-braun.de> <20170109212345.GA5513@otheros> <20170109133032.221f8669@xeon-e3> <20170110041816.GJ5513@otheros> <1484045763.1014.0.camel@sipsolutions.net> <73f29777-cf95-de99-f7a9-9d82e94c298d@nbd.name> <058f2afd-2502-e2e5-6427-1536fcd5851f@quantenna.com> <015bf651-7584-13c0-16b9-d4e29e23c96b@nbd.name> Cc: netdev@vger.kernel.org, bridge@lists.linux-foundation.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, "David S . Miller" , "M. Braun" From: Felix Fietkau Message-ID: <8d3f0bd9-8b66-ce49-ab1d-56e8c73764fc@nbd.name> (sfid-20170111_132205_106654_047D1D19) Date: Wed, 11 Jan 2017 13:21:34 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2017-01-11 13:15, IgorMitsyanko wrote: > On 01/11/2017 02:30 PM, Felix Fietkau wrote: >> On 2017-01-11 12:26, IgorMitsyanko wrote: >>> On 01/11/2017 12:27 AM, Felix Fietkau wrote: >>>> On 2017-01-10 11:56, Johannes Berg wrote: >>>>> On Tue, 2017-01-10 at 05:18 +0100, Linus Lüssing wrote: >>>>>> On Mon, Jan 09, 2017 at 01:30:32PM -0800, Stephen Hemminger wrote: >>>>>>> I wonder if MAC80211 should be doing IGMP snooping and not bridge >>>>>>> in this environment. >>>>>> In the long term, yes. For now, not quite sure. >>>>> There's no "for now" in the kernel. Code added now will have to be >>>>> maintained essentially forever. >>>> I'm not sure that putting the IGMP snooping code in mac80211 is a good >>>> idea, that would be quite a bit of code duplication. >>>> This implementation works, it's very simple, and it's quite flexible for >>>> a number of use cases. >>>> >>>> Is there any remaining objection to merging this in principle (aside >>>> from potential issues with the code)? >>>> >>>> - Felix >>>> >>> >>> Hi Felix, can we consider two examples configurations with multicast >>> traffic: >>> >>> 1. AP is a source of multicast traffic itself, no bridge on AP. For >>> example, wireless video server streaming to several clients. >>> In this situation, we can not make use of possible advantages given by >>> mc-to-uc conversion? >> You could simply put the AP interface in a bridge, no need to have any >> other bridge members present. >> >>> 2. A configuration with AP + STA + 3 client devices behind STA. >>> ----|client 1| >>> | >>> | mc |----|AP|----|STA|---|---|client 2| >>> |server| | >>> ----|client 3| >>> >>> Multicast server behind AP streams MC video traffic. All 3 clients >>> behind the STA have joined the multicast group. >>> I'm not sure if this case will be handled correctly with mc-to-uc >>> conversion in bridge on AP? >> What do you mean by "3 client devices behind STA"? Are you using a >> 4-addr STA, multicast routing, or some kind of vendor specific "client >> bridge" hackery? > > 3 client devices connected by backbone Ethernet network. Generic > case is probably STA/AP operating in 4-addr mode (more or less standard > solution as far as I know). If the AP is running in 4-addr mode, it will need to have a bridge interface anyway, because the link to the STA will be split out into a separate virtual interface (AP_VLAN iftype). In this case you don't actually need any multicast-to-unicast conversion, because the multicast traffic will be unicast on 802.11 already (due to use of 4-addr mode). - Felix