From owner-freebsd-net@FreeBSD.ORG Thu Nov 20 04:41:13 2003 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1CC0D16A4CE for ; Thu, 20 Nov 2003 04:41:13 -0800 (PST) Received: from mail.alkar.net (mail.alkar.net [195.248.191.95]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3102C43FD7 for ; Thu, 20 Nov 2003 04:41:11 -0800 (PST) (envelope-from mav@alkar.net) Received: from [212.86.226.11] (HELO alkar.net) by mail.alkar.net (CommuniGate Pro SMTP 4.1.8) with ESMTP id 122166898 for freebsd-net@freebsd.org; Thu, 20 Nov 2003 14:39:38 +0200 Message-ID: <3FBCB60A.5040706@alkar.net> Date: Thu, 20 Nov 2003 14:39:38 +0200 From: Alexander Motin User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.5b) Gecko/20030913 X-Accept-Language: ru, en-us, en MIME-Version: 1.0 To: freebsd-net@freebsd.org Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: dummynet & IP fragmentation bug X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Nov 2003 12:41:13 -0000 Hello. I have one strange problem with dummynet & IP fragmentation. I have FreeBSD 4.8-RELEASE router with few interfaces: em0: flags=8843 mtu 1500 options=3 inet 195.248.191.172 netmask 0xffffffc0 broadcast 195.248.191.191 ether 00:30:48:20:8e:7e media: Ethernet autoselect (1000baseTX ) status: active ng4: flags=88d1 mtu 1492 inet 195.248.191.172 --> 212.86.231.58 netmask 0xffffffff Interface ng4 have MTU 1492 because it is PPPoE link. When I do not use dummynet on router and somebody send a big (>1492bytes) packet to 212.86.231.58 with DontFragment flag set router generates ICMP reply message (Fragmentation Needed). This is correct. But when I use dummynet on that interface: 10170 pipe 10009 ip from any to any out xmit ng4 10175 allow ip from any to any via ng4 10009: 128.000 Kbit/s 0 ms 50 sl. 1 queues (1 buckets) droptail mask: 0x00 0x00000000/0x0000 -> 0x00000000/0x0000 BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp 0 udp 195.248.191.65/53 212.86.231.58/1118 50965 28380582 0 0 143 router stops sending that ICMP messages. Pipe is not overflowed at that tme, it is empty. -- Alexander Motin