--- 1/draft-ietf-roll-minrank-hysteresis-of-02.txt 2011-05-04 01:15:49.000000000 +0200 +++ 2/draft-ietf-roll-minrank-hysteresis-of-03.txt 2011-05-04 01:15:49.000000000 +0200 @@ -1,18 +1,18 @@ Networking Working Group O. Gnawali Internet-Draft P. Levis Intended status: Standards Track Stanford University -Expires: October 29, 2011 April 27, 2011 +Expires: November 4, 2011 May 03, 2011 The Minimum Rank Objective Function with Hysteresis - draft-ietf-roll-minrank-hysteresis-of-02 + draft-ietf-roll-minrank-hysteresis-of-03 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 Objective Function with Hysteresis (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 @@ -33,21 +33,21 @@ and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on October 29, 2011. + This Internet-Draft will expire on November 4, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -61,28 +61,27 @@ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The Minimum Rank Objective Function with Hysteresis . . . . . 4 3.1. Computing the Path cost . . . . . . . . . . . . . . . . . 4 3.2. Parent Selection . . . . . . . . . . . . . . . . . . . . . 5 3.3. Computing Rank . . . . . . . . . . . . . . . . . . . . . . 6 3.4. Advertising the Path Cost . . . . . . . . . . . . . . . . 7 3.5. Working Without Metric Containers . . . . . . . . . . . . 7 4. Using MRHOF for Metric Maximization . . . . . . . . . . . . . 7 - 5. Settings of RPL parameters . . . . . . . . . . . . . . . . . . 8 - 6. MRHOF Variables and Parameters . . . . . . . . . . . . . . . . 8 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 - 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 10.1. Normative References . . . . . . . . . . . . . . . . . . . 9 - 10.2. Informative References . . . . . . . . . . . . . . . . . . 9 + 5. MRHOF Variables and Parameters . . . . . . . . . . . . . . . . 8 + 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 + 9.2. Informative References . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction An objective function specifies how RPL [I-D.ietf-roll-rpl] selects paths. Objective functions can choose paths based on routing metrics or constraints. For example, if an RPL instance uses an objective function that minimizes hop-count, RPL will select paths with minimum hop count. @@ -313,25 +312,21 @@ to the best path. This is the path cost for the DAG root. Example, the best link reliability has a value of 1. Metrics are all positive. Example, link reliability is always positive. For metrics meeting the above conditions, the problem of maximizing the metric value is equivalent to minimizing the negative of the metric value. MRHOF is not required to work with these metrics. -5. Settings of RPL parameters - - The MinHopRankIncrease parameter MUST be set to 1. - -6. MRHOF Variables and Parameters +5. MRHOF Variables and Parameters MRHOF uses the following variable: cur_min_path_cost: The cost of the path from a node through its preferred parent to the root computed at the last parent selection. MRHOF uses the following parameters: MAX_LINK_METRIC: Maximum allowed value for the selected link @@ -365,43 +360,43 @@ MIN_PATH_COST: 0. At root, the expected transmission count is 0. PARENT_SWITCH_THRESHOLD: 1.5. Switch to a new path only if it is expected to require at least 1.5 fewer transmission than the current path. PARENT_SET_SIZE: 3. If the preferred parent is not available, two candidate parents are still available without triggering a new round of route discovery. -7. Acknowledgements +6. Acknowledgements Thanks to Antonio Grilo, Nicolas Tsiftes, Matteo Paris, JP Vasseur, and Phoebus Chen for their comments. -8. IANA Considerations +7. IANA Considerations This specification requires an allocated OCP. A value of 1 is requested. -9. Security Considerations +8. Security Considerations Security considerations to be developed in accordance to the output of the WG. -10. References +9. References -10.1. Normative References +9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. -10.2. Informative References +9.2. Informative References [I-D.ietf-roll-routing-metrics] Vasseur, J. and D. Networks, "Routing Metrics used for Path Calculation in Low Power and Lossy Networks", draft-ietf-roll-routing-metrics-01 (work in progress), October 2009. [I-D.ietf-roll-rpl] Winter, T., Thubert, P., and R. Team, "RPL: IPv6 Routing Protocol for Low power and Lossy Networks",