Re: [dhcwg] MTU option for DHCPv6?

Simon Hobson <dhcp1@thehobsons.co.uk> Thu, 28 July 2016 15:45 UTC

Return-Path: <dhcp1@thehobsons.co.uk>
X-Original-To: dhcwg@ietfa.amsl.com
Delivered-To: dhcwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 6482D12D76A for <dhcwg@ietfa.amsl.com>; Thu, 28 Jul 2016 08:45:32 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.187
X-Spam-Level:
X-Spam-Status: No, score=-3.187 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RP_MATCHES_RCVD=-1.287] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HN1XCRDa7uV5 for <dhcwg@ietfa.amsl.com>; Thu, 28 Jul 2016 08:45:30 -0700 (PDT)
Received: from patsy.thehobsons.co.uk (patsy.thehobsons.co.uk [81.174.135.208]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id AFE7512B005 for <dhcwg@ietf.org>; Thu, 28 Jul 2016 08:45:30 -0700 (PDT)
X-Virus-Scanned: Debian amavisd-new at patsy.thehobsons.co.uk
Received: from [192.168.1.55] (lan.furness.net [84.9.59.220]) by patsy.thehobsons.co.uk (Postfix) with ESMTPSA id 41FAB1BC77 for <dhcwg@ietf.org>; Thu, 28 Jul 2016 15:45:26 +0000 (UTC)
Content-Type: text/plain; charset=windows-1252
Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\))
From: Simon Hobson <dhcp1@thehobsons.co.uk>
In-Reply-To: <00e69d1c8aaa4d44859f88e0793d2679@XCH15-05-05.nw.nos.boeing.com>
Date: Thu, 28 Jul 2016 16:45:25 +0100
Content-Transfer-Encoding: quoted-printable
Message-Id: <B1F3ABB8-E1B8-4D9E-98A0-ACF3E35D88B3@thehobsons.co.uk>
References: <8c706ad593cc403d9e738c7aafec8360@XCH15-05-05.nw.nos.boeing.com> <5671d2f3bf364bec9b70ab8cbb9cd2a9@XCH-ALN-003.cisco.com> <9db5a86d50314519b4fcc4589717f802@XCH15-05-05.nw.nos.boeing.com> <f98d75f73d224798a406084fdb4cdedc@XCH-ALN-003.cisco.com> <F22A046E-27FA-4EED-9699-70A6B3D49A66@gmx.com> <CAKD1Yr0nw09qss1YMi1CLqjH+iYAaVTCP4xZLsj7eNwWyLUa6w@mail.gmail.com> <1eea216f2f914eddb73eeca7903c48d2@XCH15-05-05.nw.nos.boeing.com> <CAKD1Yr2o0wyLT1YFx-j=FuZecqpo8BbNr6bZbOr0cF1E_d639Q@mail.gmail.com> <00e69d1c8aaa4d44859f88e0793d2679@XCH15-05-05.nw.nos.boeing.com>
To: dhcwg@ietf.org
X-Mailer: Apple Mail (2.1510)
Archived-At: <https://mailarchive.ietf.org/arch/msg/dhcwg/OnpYNY6_lF34sofefIBItHAubIY>
Subject: Re: [dhcwg] MTU option for DHCPv6?
X-BeenThere: dhcwg@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: <dhcwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dhcwg>, <mailto:dhcwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dhcwg/>
List-Post: <mailto:dhcwg@ietf.org>
List-Help: <mailto:dhcwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dhcwg>, <mailto:dhcwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 28 Jul 2016 15:45:32 -0000

"Templin, Fred L" <Fred.L.Templin@boeing.com> wrote:

> > What's wrong with adding the MTU option to that RA? That is supported by pretty much all routers and clients today.
>  
> Being lazy as I am, I just don’t want to have to send multiple messages to get
> all of the configuration information the client needs. If the DHCPv6 Reply
> contains all configuration information, then there is no need to also perform
> an RS/RA just to get the MTU value.

I'm curious. OK I've probably missed a few things, but I was under the impression that clients won't (can't ?) do DHCPv6 unless the RA tells them it's a managed network. Also, if clients are self-configuring multiple addresses, doesn't that imply the RAs they are acting on have the wrong options set ?

And given that (AIUI) DHCPv6 doesn't include any routing information (as that's supposed to come from the RAs), how are the clients getting that information ?