Re: [6tisch] Benjamin Kaduk's Discuss on draft-ietf-6tisch-msf-12: (with DISCUSS and COMMENT)

Benjamin Kaduk <> Tue, 31 March 2020 23:43 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 061A53A0D6B; Tue, 31 Mar 2020 16:43:14 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: 0
X-Spam-Status: No, score=0 tagged_above=-999 required=5 tests=[SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id q-ikcKdSzi5I; Tue, 31 Mar 2020 16:43:12 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id CA75F3A0D90; Tue, 31 Mar 2020 16:43:08 -0700 (PDT)
Received: from ([]) (authenticated bits=56) (User authenticated as kaduk@ATHENA.MIT.EDU) by (8.14.7/8.12.4) with ESMTP id 02VNh0qY021656 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 31 Mar 2020 19:43:03 -0400
Date: Tue, 31 Mar 2020 16:43:00 -0700
From: Benjamin Kaduk <>
To: =?utf-8?B?TWFsacWhYSBWdcSNaW5pxIc=?= <>
Cc: Tengfei Chang <>, The IESG <>,, 6tisch <>, 6tisch-chairs <>, "Pascal Thubert (pthubert)" <>
Message-ID: <>
References: <> <> <> <>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <>
User-Agent: Mutt/1.12.1 (2019-06-15)
Archived-At: <>
Subject: Re: [6tisch] Benjamin Kaduk's Discuss on draft-ietf-6tisch-msf-12: (with DISCUSS and COMMENT)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Discuss link layer model for Deterministic IPv6 over the TSCH mode of IEEE 802.15.4e, and impacts on RPL and 6LoWPAN such as resource allocation" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 31 Mar 2020 23:43:20 -0000

Hi Mališa,

On Wed, Mar 25, 2020 at 10:37:57PM +0100, Mališa Vučinić wrote:
> Hi Ben,
> There has been an extensive discussion on this issue in the WG. As Tengfei stated, since MSF operates exclusively at L2, reading DSCP values from the IPv6 header would constitute a layer violation. It was decided that MSF would implement the recommendation from draft-ietf-6tisch-minimal-security by recommending the rate limit on DSCP-tagged traffic, at IPv6 layer as outlined in Security Considerations. That said, other scheduling functions that may operate higher up in the stack, e.g. to establish end-to-end tracks between nodes in a mesh, may adhere to this requirement from minimal-security. Therefore, for the sake of future scheduling functions that may get standardized, it was deemed appropriate to leave the recommendation in minimal-security as-is.
> Hope that clarifies.

It does help clarify, thanks.
I'm still not happy about ignoring the SHOULD from -minimal-security but
can't really refute the technical points being made, so I will remove the
Discuss point about it.

That said, it seems like a slight rewording of -minimal-security might be
in order, since:

   AF43.  Companion SF documents SHOULD specify how this recommended
   behavior is achieved.  One example is the 6TiSCH Minimal Scheduling
   Function [I-D.ietf-6tisch-msf].

seems to imply that MSF is an example of "specify[ing] how this recommended
behavior is achieved", since it is just left to "the implementation" (i.e.,
not fully specified).