From owner-freebsd-isp@FreeBSD.ORG Fri Mar 30 13:34:00 2007 Return-Path: X-Original-To: freebsd-isp@freebsd.org Delivered-To: freebsd-isp@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id F06D416A400 for ; Fri, 30 Mar 2007 13:34:00 +0000 (UTC) (envelope-from netslists@gmail.com) Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.241]) by mx1.freebsd.org (Postfix) with ESMTP id AC3ED13C4C1 for ; Fri, 30 Mar 2007 13:34:00 +0000 (UTC) (envelope-from netslists@gmail.com) Received: by an-out-0708.google.com with SMTP id c24so490748ana for ; Fri, 30 Mar 2007 06:34:00 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=NpZPmTsrgQmkdlvvw/MFwyZOYvpB6rAnA2RWGU00awNESmWATtJ6m6HIxhV4fW5Dj0TRckr0R4bg2NL+ckcERpHhtCp8/MrTXiXq/F3zaKVixbxhCiB7hsumBZu4NUHrBNL9Eg2loILY4wU3wkzgUNfdNMFJjXAUE43b3dt6Z5s= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=T+HJJynAkRA1EFVIzNeO0mvgbSHYxSpvEEjOluru90ZcaSdq0HHaB4StEfl23M13PBXGWLsRtZArRpIDusO8N/9YbBf14OhuLQ0ZRbzaRzUu6yskVCv/Q55pRXX007wd8T5/qmoqSJeH3meFpVshlrVbekwYNa7x5vEL6jrvCHo= Received: by 10.100.144.11 with SMTP id r11mr1287583and.1175259972906; Fri, 30 Mar 2007 06:06:12 -0700 (PDT) Received: from ?192.168.12.8? ( [65.33.136.97]) by mx.google.com with ESMTP id c9sm2306807ana.2007.03.30.06.06.11; Fri, 30 Mar 2007 06:06:11 -0700 (PDT) Message-ID: <460D0B83.2010902@gmail.com> Date: Fri, 30 Mar 2007 09:07:15 -0400 From: Sten Daniel Soersdal User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: eternityos@free.fr References: <1175128095.460b081f94385@imp.free.fr> In-Reply-To: <1175128095.460b081f94385@imp.free.fr> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: "freebsd-isp@freebsd.org" Subject: Re: MTU settings. X-BeenThere: freebsd-isp@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Internet Services Providers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Mar 2007 13:34:01 -0000 eternityos@free.fr wrote: > > Hi everyone :) > > Recently, we changed our internet connection to a ppp based (2Mbps). > So naturaly, I thought about changing the MTU of my interfaces on the FreeBSD > NAT router. > So I set it to 576 instead of the default, 1500 on the two interfaces, LAN and > WAN. > In what I have seen, 576 is the natural mtu for a ppp connection. 1500 is the natural mtu for ppp (lesser mtu sizes are the exception). You also contract a wide range of hard to diagnose problems, if you are not familiar with diagnosing mtu problems. > > Right away after this change, the internet connection blocked. I only got it > back setting the mtu back at 1500. > > Why did this block ? > Between the modem and the NAT router, we have a cisco router, I didn't change > it's mtu yet, would it be the cause ? It has to be negotiated during connection. ppp is a protocol which preferres the same settings on both ends of the ppp connection. Or atleast compatible ones. -- Sten Daniel Soersdal