draft-ietf-roll-of0-02.txt   draft-ietf-roll-of0-03.txt 
Networking Working Group P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track June 2, 2010 Intended status: Standards Track July 29, 2010
Expires: December 4, 2010 Expires: January 30, 2011
RPL Objective Function 0 RPL Objective Function 0
draft-ietf-roll-of0-02 draft-ietf-roll-of0-03
Abstract Abstract
The Routing Protocol for Low Power and Lossy Networks (RPL) defines a The Routing Protocol for Low Power and Lossy Networks (RPL) defines a
generic Distance Vector protocol for Low Power and Lossy Networks generic Distance Vector protocol for Low Power and Lossy Networks
(LLNs). RPL is instantiated to honor a particular routing objective/ (LLNs). RPL is instantiated to honor a particular routing objective/
constraint by the adding a specific Objective Function (OF) that is constraint by the adding a specific Objective Function (OF) that is
designed to solve that problem. This specification defines a basic designed to solve that problem. This specification defines a basic
OF, OF0, that uses only the abstract properties exposed in RPL OF, OF0, that uses only the abstract properties exposed in RPL
messages to maximize connectivity. messages to maximize connectivity.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 4, 2010. This Internet-Draft will expire on January 30, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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desirable and floating DAGs will form, rooted at the nodes with the desirable and floating DAGs will form, rooted at the nodes with the
highest administrative preference. highest administrative preference.
The metric used in OF0 is the RPL Rank, as defined in The metric used in OF0 is the RPL Rank, as defined in
[I-D.ietf-roll-rpl]. Using a metric that in essence is similar to [I-D.ietf-roll-rpl]. Using a metric that in essence is similar to
hop count implies that the quality of the connectivity should be hop count implies that the quality of the connectivity should be
asserted so that only neighbors with a good enough connectivity are asserted so that only neighbors with a good enough connectivity are
presented to the OF. How that connectivity is asserted and presented to the OF. How that connectivity is asserted and
maintained is out of scope. maintained is out of scope.
Hop count used in wireless networks will tend to favor paths with
long distance links and non optimal connectivity properties. As a
result, the link selection must be very conservative, and the
available link set is thus constrained. In some situations, this
might end up partitioning the network. For those reasons, the use of
hop count only is generally not recommended in wireless networks.
The default step of Rank is DEFAULT_RANK_INCREMENT for each hop. An The default step of Rank is DEFAULT_RANK_INCREMENT for each hop. An
implementation MAY allow a step between MINIMUM_RANK_INCREMENT and implementation MAY allow a step between MINIMUM_RANK_INCREMENT and
MAXIMUM_RANK_INCREMENT to reflect a large variation of link quality MAXIMUM_RANK_INCREMENT to reflect a large variation of link quality
by units of MINIMUM_RANK_INCREMENT. In other words, the least by units of MINIMUM_RANK_INCREMENT. In other words, the least
significant octet in the Rank is not used. significant octet in the Rank is not used.
It MAY stretch its step of Rank by up to MAXIMUM_RANK_STRETCH in It MAY stretch its step of Rank by up to MAXIMUM_RANK_STRETCH in
order to enable the selection of a sibling when only one parent is order to enable the selection of a sibling when only one parent is
available. For instance, say that a node computes a step of Rank of available. For instance, say that a node computes a step of Rank of
4 units of MINIMUM_RANK_INCREMENT from a preferred parent with a Rank 4 units of MINIMUM_RANK_INCREMENT from a preferred parent with a Rank
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value of 0 is suggested. value of 0 is suggested.
9. Security Considerations 9. Security Considerations
Security Considerations for OCP/OF are to be developed in accordance Security Considerations for OCP/OF are to be developed in accordance
with recommendations laid out in, for example, with recommendations laid out in, for example,
[I-D.tsao-roll-security-framework]. [I-D.tsao-roll-security-framework].
10. Acknowledgements 10. Acknowledgements
Most specific thanks to Tim Winter, JP Vasseur, Julien Abeille and Most specific thanks to Tim Winter, JP Vasseur, Julien Abeille,
Mathilde Durvy for in-depth review and first hand implementer's Mathilde Durvy, Teco Boot, Navneet Agarwal and Henning Rogge for in-
feedback. depth review and first hand implementer's feedback.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
11.2. Informative References 11.2. Informative References
[I-D.ietf-roll-building-routing-reqs] [I-D.ietf-roll-building-routing-reqs]
Martocci, J., Riou, N., Mil, P., and W. Vermeylen, Martocci, J., Riou, N., Mil, P., and W. Vermeylen,
"Building Automation Routing Requirements in Low Power and "Building Automation Routing Requirements in Low Power and
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Lossy Networks", draft-ietf-roll-building-routing-reqs-07 Lossy Networks", draft-ietf-roll-building-routing-reqs-07
(work in progress), September 2009. (work in progress), September 2009.
[I-D.ietf-roll-home-routing-reqs] [I-D.ietf-roll-home-routing-reqs]
Brandt, A., Buron, J., and G. Porcu, "Home Automation Brandt, A., Buron, J., and G. Porcu, "Home Automation
Routing Requirements in Low Power and Lossy Networks", Routing Requirements in Low Power and Lossy Networks",
draft-ietf-roll-home-routing-reqs-08 (work in progress), draft-ietf-roll-home-routing-reqs-08 (work in progress),
September 2009. September 2009.
[I-D.ietf-roll-routing-metrics] [I-D.ietf-roll-routing-metrics]
Vasseur, J., Kim, M., Networks, D., and H. Chong, "Routing Vasseur, J., Kim, M., Networks, D., Dejean, N., and D.
Metrics used for Path Calculation in Low Power and Lossy Barthel, "Routing Metrics used for Path Calculation in Low
Networks", draft-ietf-roll-routing-metrics-06 (work in Power and Lossy Networks",
progress), April 2010. draft-ietf-roll-routing-metrics-08 (work in progress),
July 2010.
[I-D.ietf-roll-rpl] [I-D.ietf-roll-rpl]
Winter, T., Thubert, P., and R. Team, "RPL: IPv6 Routing Winter, T., Thubert, P., and R. Team, "RPL: IPv6 Routing
Protocol for Low power and Lossy Networks", Protocol for Low power and Lossy Networks",
draft-ietf-roll-rpl-08 (work in progress), May 2010. draft-ietf-roll-rpl-10 (work in progress), June 2010.
[I-D.ietf-roll-terminology] [I-D.ietf-roll-terminology]
Vasseur, J., "Terminology in Low power And Lossy Vasseur, J., "Terminology in Low power And Lossy
Networks", draft-ietf-roll-terminology-03 (work in Networks", draft-ietf-roll-terminology-03 (work in
progress), March 2010. progress), March 2010.
[I-D.tsao-roll-security-framework] [I-D.tsao-roll-security-framework]
Tsao, T., Alexander, R., Daza, V., and A. Lozano, "A Tsao, T., Alexander, R., Daza, V., and A. Lozano, "A
Security Framework for Routing over Low Power and Lossy Security Framework for Routing over Low Power and Lossy
Networks", draft-tsao-roll-security-framework-02 (work in Networks", draft-tsao-roll-security-framework-02 (work in
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