[Roll] Fwd: New Version Notification for draft-ietf-roll-minrank-hysteresis-of-11.txt
Omprakash Gnawali <gnawali@cs.uh.edu> Sat, 30 June 2012 06:17 UTC
Return-Path: <gnawali@cs.uh.edu>
X-Original-To: roll@ietfa.amsl.com
Delivered-To: roll@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 76D6121F86E0 for <roll@ietfa.amsl.com>; Fri, 29 Jun 2012 23:17:22 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -5.577
X-Spam-Level:
X-Spam-Status: No, score=-5.577 tagged_above=-999 required=5 tests=[AWL=0.400, BAYES_00=-2.599, FM_FORGED_GMAIL=0.622, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id t1mvzEZk-t1l for <roll@ietfa.amsl.com>; Fri, 29 Jun 2012 23:17:21 -0700 (PDT)
Received: from dijkstra.cs.uh.edu (dijkstra.cs.uh.edu [129.7.240.12]) by ietfa.amsl.com (Postfix) with ESMTP id 1D29221F86AF for <roll@ietf.org>; Fri, 29 Jun 2012 23:17:20 -0700 (PDT)
Received: from localhost (dijkstra.cs.uh.edu [127.0.0.1]) by dijkstra.cs.uh.edu (Postfix) with ESMTP id 9103623CAB8 for <roll@ietf.org>; Sat, 30 Jun 2012 01:17:17 -0500 (CDT)
X-Virus-Scanned: amavisd-new at cs.uh.edu
Received: from dijkstra.cs.uh.edu ([127.0.0.1]) by localhost (dijkstra.cs.uh.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id MXjVK3oLupP6 for <roll@ietf.org>; Sat, 30 Jun 2012 01:17:14 -0500 (CDT)
Received: from it.cs.uh.edu (www2.cs.uh.edu [129.7.240.6]) by dijkstra.cs.uh.edu (Postfix) with ESMTP id 286CA23CAB3 for <roll@ietf.org>; Sat, 30 Jun 2012 01:17:14 -0500 (CDT)
Received: from mail-pz0-f44.google.com (mail-pz0-f44.google.com [209.85.210.44]) by it.cs.uh.edu (Postfix) with ESMTP id E340F2A280C0 for <roll@ietf.org>; Sat, 30 Jun 2012 01:16:28 -0500 (CDT)
Received: by dacx6 with SMTP id x6so5447053dac.31 for <roll@ietf.org>; Fri, 29 Jun 2012 23:17:16 -0700 (PDT)
Received: by 10.68.130.9 with SMTP id oa9mr12479969pbb.95.1341037036103; Fri, 29 Jun 2012 23:17:16 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.66.9.202 with HTTP; Fri, 29 Jun 2012 23:16:41 -0700 (PDT)
In-Reply-To: <20120630061204.6274.9134.idtracker@ietfa.amsl.com>
References: <20120630061204.6274.9134.idtracker@ietfa.amsl.com>
From: Omprakash Gnawali <gnawali@cs.uh.edu>
Date: Fri, 29 Jun 2012 23:16:41 -0700
Message-ID: <CAErDfUTCQt4E5PxbGeRgQHG=kJc+ekJeU14C16_ZUXjPef5afA@mail.gmail.com>
To: ROLL WG <roll@ietf.org>
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: quoted-printable
Subject: [Roll] Fwd: New Version Notification for draft-ietf-roll-minrank-hysteresis-of-11.txt
X-BeenThere: roll@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Routing Over Low power and Lossy networks <roll.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/roll>, <mailto:roll-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/roll>
List-Post: <mailto:roll@ietf.org>
List-Help: <mailto:roll-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/roll>, <mailto:roll-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 30 Jun 2012 06:17:22 -0000
Here are the changes made to this draft to address all the DISCUSS items. COMMENTs were also addressed but not listed here. Here is a link to -11: http://tools.ietf.org/html/draft-ietf-roll-minrank-hysteresis-of-11 And here is a link to the diff between -10 and -11: http://tools.ietf.org/rfcdiff?difftype=--hwdiff&url2=draft-ietf-roll-minrank-hysteresis-of-11.txt How the DISCUSS items were addressed --- Brian Haberman: 1. Discuss - In sections 3.1 and 3.2.1, the draft says that messages can be delayed but should not be delayed too much? How much is too much? Is it dependent on the metric being used? Are there guidelines that should be provided? If different implementations try to interact, will their selection of delay values hinder performance/stability of the RPL-based network? Fixed. It now gives an example of reasonable delay: Trickle minimum interval (6550) and says longer delays will lead to stale information, suboptimal paths. ------ 2. Discuss - Section 5 says, "The best values for these parameters should be experimentally determined." Is this guidance to implementers to figure out what values to support in their implementation or advice to operators to test a range of values for their particular deployment? As a standards-track document, this type of nebulous statement concerns me from a variety of perspectives. Fixed as: The best values for these parameters are determined by the requirement of the specific RPL deployment. For instance, if we use ETX as the selected metric and UDP as the transport protocol, we should use a small MAX_LINK_METRIC (e.g., ETX of 1.1) so that link layer retransmissions are sufficient to provide a good chance of end-to-end reliability. ------ 3. Discuss - Section 8 asks IANA to allocate a code point, but where in the draft is that code point used? Is it used as a part of the transmission logic in section 3.4? This is a RPL parameter (not used in MRHOF) as suggested in the text: <t>This specification requires a value allocated from the "Objective Code Point (OCP)" sub-registry of the "Routing Protocol for Low Power and Lossy Networks (RPL)" registry. A value of 1 is suggested.</t> ------ Comment - acronyms should be referenced/expanded in first use. Fixed. ----- Martin Steimerling Discuss 1: Is there any recommendation or further reading on what the time is to be used to perform the periodically updates? Re-computing state periodically might be a good thing, but I would expect that a Standards Track document is much more specific on this. Fixed. .. Discuss 2: How much is the 'later time'? I would expect that a Standards Track document is much more specific on this, other than do whatever you think is appropriate. Fixed. ... Discuss 3: Is there any reference on how the WG came to the below numbers? This would be good for people trying to follow this up in the future. They might need to know how to came to these numbers. Here are the recommended numbers with proper ETX representation - MAX_LINK_METRIC: 512. MAX_PATH_COST: 32768. PARENT_SWITCH_THRESHOLD: 192. PARENT_SET_SIZE: 3. ALLOW_FLOATING_ROOT: 0. and the draft now cites: IP is Dead, Long Live IP for Wireless Sensor Networks Jonathan W. Hui and David E. Culler Proceedings of the 6th International Conference on Embedded Networked Sensor Systems ---- Discuss 1-4: 1. Why is one objective function defined for several potential metrics? The details of MRHOF seem to preclude the establishment of several RPL instances in an LLN, each of which uses MRHOF with a different selected metric. 2. How are the nodes in the RPL instance informed about the selected metric? My understanding of RPL is that only the objective function is included in the DIO received as an advertisement for a particular RPL instance, which means a node can't know the selected metric for that RPL instance and can't meaningfully decide among multiple RPL instances all using MRHOF as the objective function. As a followup to (1), if there were a way to encode the selected metric for a RPL instance in the DAO, a node would be able to select which RPL instance to use for a particular type of traffic. 3. Based on (1) and (2), would configuration and selection issues be ameliorated if the five candidate selected metrics were each asssigned a separate objective function? Use of a separate OF code point for each of the five possible selected metrics would allow multiple RPL instances. 4. Related to the above, I don't see anything in section 6 about managing the selected metric. Don't all of the nodes that join a RPL instance using MRHOF have to be configured to use the same selected metric? Fixed with this definition in the terminology section: <t hangText="Selected metric:">The metric chosen by the network operator to use for path selection. MRHOF supports using a single metric for path selection. The decision to use a metric (other than ETX) as the selected metric is indicated by the presence of the chosen metric in the DIO metric container. The selection of the ETX metric is indicated by the absence of the metric container.</t> ---- Discuss 5 - In section 3.2.2: a node MAY use a different objective function to select which of these neighbors should be considered to have the lowest cost. seems to contradict the statement in the Introduction that "all nodes in a network use a common OF." Should "different objective function" be replaced with "some other selection criteria?" Fixed: <t>If there are multiple neighbors which share the smallest path cost, a node MAY use a different selection criteria to select which of these neighbors should be considered to have the lowest cost.</t> ---- Discuss 6 - In section 5, are the RECOMMENDED values appropriate for all selected metrics or just for ETX? Are there any references that might be cited that would give background on the working group experience with ETX and the development of the recommended values? Fixed. See above. ---- 7. In section 6.1, why not "MUST support the DODAG Configuration option?" I don't see any RFC 2119 requirements on the implementation of the DODAG Configuration option (which would appera to be an oversight), but I don't understand how a node can operate in a RPL instance without, for example, being able to determine the Objective Function used by that instance. Fixed: <t>A MRHOF implementation MUST support the DODAG Configuration option as described in <xref target="RFC6550"/> and apply the parameters it specifies. Care should be taken in the relationship between the MRHOF ... - om_p ---------- Forwarded message ---------- From: <internet-drafts@ietf.org> Date: Fri, Jun 29, 2012 at 11:12 PM Subject: New Version Notification for draft-ietf-roll-minrank-hysteresis-of-11.txt To: gnawali@cs.uh.edu Cc: pal@cs.stanford.edu A new version of I-D, draft-ietf-roll-minrank-hysteresis-of-11.txt has been successfully submitted by Omprakash Gnawali and posted to the IETF repository. Filename: draft-ietf-roll-minrank-hysteresis-of Revision: 11 Title: The Minimum Rank with Hysteresis Objective Function Creation date: 2012-06-29 WG ID: roll Number of pages: 14 URL: http://www.ietf.org/internet-drafts/draft-ietf-roll-minrank-hysteresis-of-11.txt Status: http://datatracker.ietf.org/doc/draft-ietf-roll-minrank-hysteresis-of Htmlized: http://tools.ietf.org/html/draft-ietf-roll-minrank-hysteresis-of-11 Diff: http://tools.ietf.org/rfcdiff?url2=draft-ietf-roll-minrank-hysteresis-of-11 Abstract: The Routing Protocol for Low Power and Lossy Networks (RPL) uses objective functions to construct routes that optimize or constrain the routes it selects and uses. This specification describes the Minimum Rank with Hysteresis Objective Function (MRHOF), an objective function that selects routes that minimize a metric, while using hysteresis to reduce churn in response to small metric changes. MRHOF works with metrics that are additive along a route, and the metric it uses is determined by the metrics RPL Destination Information Object (DIO) messages advertise. The IETF Secretariat
- [Roll] Fwd: New Version Notification for draft-ie… Omprakash Gnawali