From owner-freebsd-stable@FreeBSD.ORG Thu Jul 12 19:54:37 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 47FE216A400 for ; Thu, 12 Jul 2007 19:54:37 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from mail-out3.apple.com (mail-out3.apple.com [17.254.13.22]) by mx1.freebsd.org (Postfix) with ESMTP id 3103F13C44B for ; Thu, 12 Jul 2007 19:54:37 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from relay8.apple.com (relay8.apple.com [17.128.113.38]) by mail-out3.apple.com (Postfix) with ESMTP id 0FA1EB91BF5; Thu, 12 Jul 2007 12:54:11 -0700 (PDT) Received: from relay8.apple.com (unknown [127.0.0.1]) by relay8.apple.com (Symantec Mail Security) with ESMTP id EEA6A40079; Thu, 12 Jul 2007 12:54:10 -0700 (PDT) X-AuditID: 11807126-a18ccbb0000007dd-ab-469686e2346e Received: from [17.214.13.96] (int-si-a.apple.com [17.128.113.41]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by relay8.apple.com (Apple SCV relay) with ESMTP id D3E9B40053; Thu, 12 Jul 2007 12:54:10 -0700 (PDT) In-Reply-To: <4696823B.9020107@seclark.us> References: <469624D1.20108@seclark.us> <4696823B.9020107@seclark.us> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Chuck Swiger Date: Thu, 12 Jul 2007 12:54:10 -0700 To: Stephen.Clark@seclark.us X-Mailer: Apple Mail (2.752.2) X-Brightmail-Tracker: AAAAAA== Cc: freebsd-stable@freebsd.org Subject: Re: pmtud + ipnat RELENG_6_2 appears to be broken X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Jul 2007 19:54:37 -0000 On Jul 12, 2007, at 12:34 PM, Stephen Clark wrote: > Did something change in 6.2? If my mtu size on rl0 is 1280 it won't > accept a larger incoming packet. Nothing changed; that is the expected behavior. (Modulo support for 4-byte VLAN tags.) > kernel: rl0: discard oversize frame (ether type 800 flags 3 len > 1514 > max > 1294) > > I don't think it worked this way in the past. Well, it did. :-) > Won't this affect pmtud? Nope. > man page for ifconfig says mtu limits size of "transmission" not > reception. > > "mtu n Set the maximum transmission unit of the interface to > n, default > is interface specific." The MTU is actually defined in reference to a network segment such as an "ethernet collision domain", and applies to all machines sending traffic to that segment. If the MTU is really 1280, nobody else should be sending larger packets, and the drivers will drop any larger packets they receive and generate the appropriate ICMP error.... -- -Chuck