From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753237AbbHMOso (ORCPT ); Thu, 13 Aug 2015 10:48:44 -0400 Received: from mx0b-000f0801.pphosted.com ([67.231.152.113]:26651 "EHLO mx0b-000f0801.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752973AbbHMOsl (ORCPT ); Thu, 13 Aug 2015 10:48:41 -0400 From: Philip Downey To: David Miller CC: "kuznet@ms2.inr.ac.ru" , "jmorris@namei.org" , "yoshfuji@linux-ipv6.org" , "kaber@trash.net" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" Subject: RE: [PATCH] IGMP: Inhibit reports for local multicast groups Thread-Topic: [PATCH] IGMP: Inhibit reports for local multicast groups Thread-Index: AQHQ1Rn2gdhQ+D2dyEmVK8LQ/fuaRp4I5imAgAETqMA= Date: Thu, 13 Aug 2015 14:48:23 +0000 Message-ID: <57f72e6a6f024628bd18ef4b139ac31e@EMEAWP-EXMB12.corp.brocade.com> References: <1439396033-6264-1-git-send-email-pdowney@brocade.com> <20150812.164519.1783786478654950784.davem@davemloft.net> In-Reply-To: <20150812.164519.1783786478654950784.davem@davemloft.net> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.252.53.3] Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.14.151,1.0.33,0.0.0000 definitions=2015-08-13_06:2015-08-13,2015-08-13,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=1 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1506180000 definitions=main-1508130218 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David Thanks for taking the time to review and comment. This is my first upstream request so please forgive any ignorance on my part. I have added a new proposed commit wording below with a view to agreeing the content before resubmitting the patch. I hope it is sufficient to address your concerns. IGMP: Inhibit reports for local multicast groups The range of addresses between 224.0.0.0 and 224.0.0.255 inclusive, is reserved for the use of routing protocols and other low-level topology discovery or maintenance protocols, such as gateway discovery and group membership reporting. Multicast routers should not forward any multicast datagram with destination addresses in this range, regardless of its TTL. Currently, IGMP reports are generated for this reserved range of addresses even though a router will ignore this information since it has no purpose. However, the presence of reserved group addresses in an IGMP membership report uses up network bandwidth and can also obscure addresses of interest when inspecting membership reports using packet inspection or debug messages. IGMP reports for local multicast groups can now be inhibited by means of a system control variable (setting the value to zero). To retain backwards compatibility the previous behaviour is retained by default on system boot. Signed-off-by: Philip Downey Regards Philip > -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Thursday, August 13, 2015 12:45 AM > To: Philip Downey > Cc: kuznet@ms2.inr.ac.ru; jmorris@namei.org; yoshfuji@linux-ipv6.org; > kaber@trash.net; linux-kernel@vger.kernel.org; netdev@vger.kernel.org > Subject: Re: [PATCH] IGMP: Inhibit reports for local multicast groups > > From: Philip Downey > Date: Wed, 12 Aug 2015 17:13:53 +0100 > > > IGMP reports are generated for link local multicast groups (224.0.0.1 > > - 224.0.0.255) used by the routing protocols such as RIP, OSPF etc. > > In general routers do not generate reports for local multicast groups. > > > > IGMP reports for local multicast groups can now be inhibited by means > > of a system control variable (setting the value to zero). > > > > To retain backwards compatibility the previous behaviour is retained > > by default on system boot. > > > > Signed-off-by: Philip Downey > > I'm always hesitent to apply patches like this. > > I can't even understand from your explanation: > > 1) what about local reporting behavior is so bad > > 2) why you want to inhibit them at all > > For example, this: > > > In general routers do not generate reports for local multicast groups. > > Doesn't tell me anything. You need to go into more detail about this, and > explain the situation sufficiently.