From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: IGMP Unsolicited Report Interval too long for IGMPv3? Date: Thu, 25 Jul 2013 16:42:53 -0700 (PDT) Message-ID: <20130725.164253.690113010547536005.davem@davemloft.net> References: <51ED998D.7000300@youview.com> <20130722211855.GL19643@kvack.org> <20130722215108.GG6538@order.stressinduktion.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: bcrl@kvack.org, william.manley@youview.com, netdev@vger.kernel.org To: hannes@stressinduktion.org Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:51447 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755070Ab3GYXmy (ORCPT ); Thu, 25 Jul 2013 19:42:54 -0400 In-Reply-To: <20130722215108.GG6538@order.stressinduktion.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Hannes Frederic Sowa Date: Mon, 22 Jul 2013 23:51:08 +0200 > On Mon, Jul 22, 2013 at 05:18:55PM -0400, Benjamin LaHaise wrote: >> On Mon, Jul 22, 2013 at 09:43:57PM +0100, William Manley wrote: >> > If an IGMP join packet is lost you will not receive data sent to the >> > multicast group so if no data arrives from that multicast group in a >> > period of time after the IGMP join a second IGMP join will be sent. The >> > delay between joins is the "IGMP Unsolicited Report Interval". >> > >> > In the kernel this seems to be hard coded to be chosen randomly between >> > 0-10s. In our use-case (IPTV) this is too long as it can cause channel >> > change to be slow in the presence of packet loss. >> > >> > I would guess that this 10s has come from IGMPv2 RFC2236, which was >> > reduced to 1s in IGMPv3 RFC3376. >> >> Reducing the timeout does not solve the problem you are encountering, as >> any packet loss will still result in a 1 second delay. I've encountered >> similar issues dealing with LCP Echo request/replies for keepalive >> messages on PPP sessions. The correct approach is to queue the IGMP >> multicast join with a higher priority than other traffic in the system >> so that the requests are not lost due to congestion of a single queue. >> Sending packets with an 802.1p header might be appropriate in your >> use-case, or perhaps using higher priority internal queues. > > Yes, we can do a little bit better. What do you think? > > [PATCH net-next] ipv6: send igmpv3/mld packets with TC_PRIO_CONTROL > > Reported-by: William Manley > Suggested-by: Benjamin LaHaise > Signed-off-by: Hannes Frederic Sowa Ben, please give Hannes the feedback he is asking for. Thanks.