Date: Sat, 15 Jul 2000 17:08:43 -0400 (EDT) From: "Chris D. Faulhaber" <jedgar@fxp.org> To: Dan Flemming <danflemming@mac.com> Cc: doc@FreeBSD.org Subject: Re: Suggested addition to PPP FAQ - solution for Macintoshes and Black Hole DSL routers Message-ID: <Pine.BSF.4.21.0007151706280.93031-200000@pawn.primelocation.net> In-Reply-To: <3970B730.C4D28290@mac.com>
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[-- Attachment #1 --] On Sat, 15 Jul 2000, Dan Flemming wrote: > At http://www.ca.FreeBSD.org/FAQ/ppp.html#AEN3716 you have some advice > for Win9x users connecting through a FreeBSD box that's running PPPoE > and NAT. Well, Macs have the same problem (the default MTU on MacOS 9 at > least is 1500), but a different solution, which I just found. :) > See the attached patch. My SGML is not the best so I'm sure it will need a little fixing up. ----- Chris D. Faulhaber - jedgar@fxp.org - jedgar@FreeBSD.org -------------------------------------------------------- FreeBSD: The Power To Serve - http://www.FreeBSD.org [-- Attachment #2 --] Index: book.sgml =================================================================== RCS file: /home/ncvs/doc/en_US.ISO_8859-1/books/faq/book.sgml,v retrieving revision 1.70 diff -u -r1.70 book.sgml --- book.sgml 2000/07/11 21:36:22 1.70 +++ book.sgml 2000/07/15 21:05:58 @@ -7757,22 +7757,23 @@ <qandaentry id=PPPoEwithNAT> <question> - <para>Why do my Windows 98 connections freeze when I run PPPoE on the gateway</para> + <para>Why do Mac and Windows 98 connections freeze when running PPPoE on the gateway</para> </question> <answer> <para> Thanks to Michael Wozniak <email>mwozniak@netcom.ca</email> for figuring - this out: + this out and Dan Flemming <email>danflemming@mac.com</email> for the Mac + solution: </para> <para> - This is due to what's called a "Black Hole" router. Windows 98 (and - maybe other Microsoft OSs) is sending TCP packets with a requested - segment size too big to fit into a PPPoE frame (MTU is 1500 by default - for ethernet) <emphasis remap=bf>and</emphasis> have the "don't fragment" - bit set (default of TCP) and the Telco router is not sending ICMP "must + This is due to what's called a "Black Hole" router. MacOS and Windows 98 + (and maybe other Microsoft OSs) send TCP packets with a requested segment + size too big to fit into a PPPoE frame (MTU is 1500 by default for + ethernet) <emphasis remap=bf>and</emphasis> have the "don't fragment" bit + set (default of TCP) and the Telco router is not sending ICMP "must fragment" back to the www site you are trying to load. When the www server is sending you frames that don't fit into the PPPoE pipe the Telco router drops them on the floor and your page doesn't load (some @@ -7802,6 +7803,18 @@ and <quote>Q120642 - TCPIP & NBT Configuration Parameters for Windows NT </quote> for more information on changing Windoze MTU to work with a FreeBSD/NAT/PPPoE router. + </para> + + <para> + Unfortunately, MacOS does not provide an interface for changing TCP/IP + settings. However, there is commercial software available, such as + OTAdvancedTuner (OT for OpenTransport, the MacOS TCP/IP stack) by + <ulink URL="http://www.softworks.com/">Sustainable Softworks</ulink>, + that will allow users to customize TCP/IP settings. MacOS NAT users + should select <literal>ip_interface_MTU</literal> from the drop-down + menu, enter <literal>1450</literal> instead of <literal>1500</literal> + in the box, click the box next to <literal>Save as Auto + Configure</literal>, and click <literal>Make Active</literal>. </para> </answer>
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