From owner-freebsd-net@FreeBSD.ORG Sun May 12 20:30:08 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 9CF6BA3E for ; Sun, 12 May 2013 20:30:08 +0000 (UTC) (envelope-from kob6558@gmail.com) Received: from mail-oa0-f48.google.com (mail-oa0-f48.google.com [209.85.219.48]) by mx1.freebsd.org (Postfix) with ESMTP id 6BC36D68 for ; Sun, 12 May 2013 20:30:08 +0000 (UTC) Received: by mail-oa0-f48.google.com with SMTP id i4so6641256oah.7 for ; Sun, 12 May 2013 13:30:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=9+a2Up1gCOXpBJGSEERWQ/O2Ttyzh1wJP/XkFD1yuZM=; b=mIqDoAmUEEqCNyp3Az23qV3KSmEy59ahCvor38gWDXsiITMRw32VKgy5sdPwZdLNpE mNTDoaYJ37iNqcaftHS1uU9FI5YyIe9Vgmcw4az2Rr+nk3ptQmeD2bYJSmCnTGEMvu1t AeBjDk7JqtTw0NlE8VpZ86sdmnxiQHuLxPlNfYl3NGC+inryoBBAUSvHOEHqcTh/tEjz bu/akk65qGzDC6v1yewwmRcQtQj/ZE1etEHzdI+JP2tNRq5JADZmE52Vh/Q/34lORy3q PNb+pDLN01E3zVsvDITe8x9YDAIOa8OvkxGLhjwV8BlUastSy4vPgg06rO/juGq6LR++ g7lQ== MIME-Version: 1.0 X-Received: by 10.182.109.229 with SMTP id hv5mr11327534obb.61.1368390602758; Sun, 12 May 2013 13:30:02 -0700 (PDT) Sender: kob6558@gmail.com Received: by 10.76.182.76 with HTTP; Sun, 12 May 2013 13:30:02 -0700 (PDT) In-Reply-To: <20130512.130304.74693108.sthaug@nethelp.no> References: <20130509.110631.74720486.sthaug@nethelp.no> <20130512.130304.74693108.sthaug@nethelp.no> Date: Sun, 12 May 2013 13:30:02 -0700 X-Google-Sender-Auth: RruHzxSaANIWSP9o_rPpSE7Q1NA Message-ID: Subject: Re: IPv6 tunnel MTU of 1480 not effective From: Kevin Oberman To: sthaug@nethelp.no Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 Cc: jason@b0rken.org, jinmei@isc.org, freebsd-net@freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 May 2013 20:30:08 -0000 On Sun, May 12, 2013 at 4:03 AM, wrote: > > > > > However I'm only able to send IPv6 packets from my host that fit > an MTU > > > > > of 1280 even though I've set the tunnel interface and per-route > MTU to > > > > > 1480, based on the "outer" ethernet connection having an MTU of > 1500. > > > > > Hurricane Electric supports this and I've set the MTU to 1480 on > their > > > > > side as well. > > [...] > > > I complained about this at least a couple of years ago and was told by > the > > > developer (I don't recall exactly who any more) that it was right and > would > > > not be changed. I really would love to see this reconsidered before > IPv6 > > > becomes much more popular as it will simply cause confusion, but I, > too, > > > fear that it is a lost cause. > > > > What's "this" (to reconsider)? That ping6 fragments outgoing packets > > at 1280 octets (by default)? Or, more in general whether any outgoing > > IPv6 packet can initially honor the interface MTU? > > What I want to happen is: When I use ping6 *and explicitly specify a > packet size using the -s option*, I want the interface MTU to be > honored. I don't want to have to specify -m as a sort of extra "yes, > I really really mean it". > > This is, in my opinion, by far the least surprising behavior for the > user - and would then work the same as the IPv4 ping command. > > It looks like an extremely simple change to make in the ping6.c file. > > (Long term, I would like ping and ping6 to become *one* program with > default IPv4 or IPv6 based on the destination specified, and options > -4 / -6 like telnet has. Same for traceroute / traceroute6. However, > this is an aside.) > > Steinar Haug, Nethelp consulting, sthaug@nethelp.no > Sorry to be so hackneyed, but... +1 Sorry that I was unclear (and may have been last time, too). -- R. Kevin Oberman, Network Engineer E-mail: rkoberman@gmail.com