Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 9 Jan 2003 06:30:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 9 Jan 2003 06:30:27 -0500 Received: from users.linvision.com ([62.58.92.114]:61630 "EHLO abraracourcix.bitwizard.nl") by vger.kernel.org with ESMTP id ; Thu, 9 Jan 2003 06:30:25 -0500 Date: Thu, 9 Jan 2003 12:38:58 +0100 From: Rogier Wolff To: netdev@oss.sgi.com, linux-kernel@vger.kernel.org Subject: Re: ipv6 stack seems to forget to send ACKs Message-ID: <20030109123857.A15625@bitwizard.nl> References: <20030108130850.GQ22951@wiggy.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030108130850.GQ22951@wiggy.net> User-Agent: Mutt/1.3.22.1i Organization: BitWizard.nl Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5624 Lines: 87 On Wed, Jan 08, 2003 at 02:08:50PM +0100, Wichert Akkerman wrote: > > 13:57:39.812123 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9352713 win 32616 > 13:57:39.823581 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9352713:9353921(1208) ack 1 win 5712 [class 0x2] > 13:57:39.823636 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9353921 win 32616 The packet is acked about 50 us after reception. Wicked! > 13:57:39.835144 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9353921:9355129(1208) ack 1 win 5712 [class 0x2] > 13:57:39.835197 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9355129 win 32616 Same here. > 13:57:39.844277 2001:968:1::2.8000 > tornado.wiggy.net.33035: P 9355129:9355601(472) ack 1 win 5712 [class 0x2] > 13:57:39.844326 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9355601 win 32616 > 13:57:40.221776 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9355601:9356809(1208) ack 1 win 5712 [class 0x2] > 13:57:40.221846 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9356809 win 32616 > 13:57:40.233558 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9356809:9358017(1208) ack 1 win 5712 [class 0x2] > 13:57:40.233613 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9358017 win 32616 > 13:57:40.245110 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9358017:9359225(1208) ack 1 win 5712 [class 0x2] > 13:57:40.245160 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9359225 win 32616 same. same. same. > 13:57:40.282351 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 But now: No ack! Funny. > 13:57:40.284307 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9360433:9360653(220) ack 1 win 5712 Another packet, no ack! > 13:57:40.297307 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9360653:9361861(1208) ack 1 win 5712 > 13:57:40.297376 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9359225 win 32616 Another packet, but this time it SACKs the just-recieved packet. It looks as if the two packets inbetween somehow were not recognized as belonging with this connection. > 13:57:40.308222 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9362081:9363289(1208) ack 1 win 5712 [class 0x2] > 13:57:40.308271 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9359225 win 32616 new packet, recognized ok, buffered, and acked! > 13:57:40.310424 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9361861:9362081(220) ack 1 win 5712 > 13:57:40.310471 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9359225 win 32616 > 13:57:40.325396 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9363289:9363509(220) ack 1 win 5712 [class 0x2] > 13:57:40.325447 tornado.wiggy.net.33035 > 2001:968:1::2.8000: . ack 9359225 win 32616 Two more packets, and still more hints towards the other machine that we're missing 9359225-9360653 > 13:57:40.568652 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 So, it retransmits the first. but we don't see it as beloging to this connection or something, so it gets ignored. > 13:57:41.121608 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 > 13:57:42.242095 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 > 13:57:44.481379 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 > 13:57:48.963035 2001:968:1::2.8000 > tornado.wiggy.net.33035: . 9359225:9360433(1208) ack 1 win 5712 again, again, again. It looks as if somehow those two packets 9359225:9360433 and 9360433:9360653 get mangled in a way as to invalidate the checksum. This would cause "silent drop" of these packets before they were acked.... Can you check the stats counters, to see if they are indeed dropped? Roger. -- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * The Worlds Ecosystem is a stable system. Stable systems may experience * * excursions from the stable situation. We are currently in such an * * excursion: The stable situation does not include humans. *************** - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/