Networking Working Group O. Gnawali
Internet-Draft P. Levis
Intended status: BCP Stanford University
Expires: August 25, 2011 February 21, 2011
Recommendations for Efficient Implementation of RPL
draft-gnawali-roll-rpl-recommendations-00
Abstract
RPL is a flexible routing protocol applicable to a wide range of Low
Power and Lossy Networks. To enable this wide applicability, RPL
provides many configuration options and gives implementers choices on
how to implement various components of RPL. Drawing on our
experiences, we distill the design choices and configuration
parameters that lead to efficient RPL implementations and operations.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Set the Minimum Trickle Interval with Care . . . . . . . . . . 3
4. Use Large Maximum Trickle Interval . . . . . . . . . . . . . . 4
5. Poison Route Sparingly . . . . . . . . . . . . . . . . . . . . 4
6. Preserve Neighbor Information . . . . . . . . . . . . . . . . . 4
7. Slow-Down Datapath Traffic During Path Inconsistency . . . . . 4
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
10. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
11.1. Normative References . . . . . . . . . . . . . . . . . . . 5
11.2. Informative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
RPL [I-D.ietf-roll-rpl] is a routing protocol that is applicable in a
wide range of settings in networks characterized by low power and
lossy links (LLN). Because RPL is designed to work in a wide range
of settings, it offers many configuration parameters and choices in
how different mechanisms are implemented. This flexibility is
essential to ensure the wide applicability of this protocol.
One can take advantage of this flexibility to implement and configure
RPL in the most efficient way for a given network. However, it is
easy to inadvertently configure RPL to work inefficiently in the
network. These design choices must be made carefully drawing on
implementation and operational experiences.
In this document, we describe aspects of configuration and mechanisms
that impact the performance of RPL. We hope these descriptions serve
as guidelines and best practices for RPL implementers and enables
them to understand why certain design and configuration choices are
favored over others.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
This terminology used in this document is consistent with the
terminologies described in [I-D.ietf-roll-terminology],
[I-D.ietf-roll-rpl], and [I-D.ietf-roll-routing-metrics].
This document does not introduce new terms.
3. Set the Minimum Trickle Interval with Care
The minimum Trickle interval determines the fastest rate at which RPL
will send DIOs. It is not useful to have multiple DIOs in the
transmit queue at a given node. The information in the older DIOs is
likely already stale when the new DIO is generated. In systems that
cannot cancel the packets that are already in the queue, it is
advisable to set the minimum interval to be much larger than the
minimum link layer packet time.
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4. Use Large Maximum Trickle Interval
The maximum Trickle interval determines the slowest rate at which RPL
will send DIOs. It is recommended that the maximum interval is set
to several hours. A large interval does not necessarily make RPL
less agile or the routing information stale. Trickle will operate at
a rate between the minimum and maximum interval depending on the
dynamics in the network.
5. Poison Route Sparingly
It is often not necessary for a node to poison a route explicitly by
advertising a rank of INFINITY. With datapath validation, it is easy
to detect a loop and coupled with adaptive beaconing, the routes can
be repaired quickly without additional explicit mechanism for route
poisoning. Poisoning the route does not prevent loops.
6. Preserve Neighbor Information
The neighborhood information is useful even when a node detects that
it has lost a route. It is recommended that the nodes not flush the
entire or subset of the neighbor table even when a node loses its
route or detects a loop. It is sufficient to mark the nodes in the
table with the updated information that resulted in route loss or
loops, e.g., marking the particular parent with a rank of INFINITY.
7. Slow-Down Datapath Traffic During Path Inconsistency
When a node detects that a path is inconsistent through datapath
validation, it tasks the control plane to repair the topology and
make it consistent. During this time, although the route is
available, it is advisable that the data packets are sent at lower
rates to reduce contention with the control packets.
8. Acknowledgements
We will acknowledge people who contribute their experiences.
9. IANA Considerations
None.
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10. Security Considerations
Security considerations to be developed in accordance to the output
of the WG.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
11.2. 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., Brandt, A., Clausen, T., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., and J.
Vasseur, "RPL: IPv6 Routing Protocol for Low power and
Lossy Networks", draft-ietf-roll-rpl-18 (work in
progress), February 2011.
[I-D.ietf-roll-terminology]
Vasseur, J., "Terminology in Low power And Lossy
Networks", draft-ietf-roll-terminology-01 (work in
progress), May 2009.
Authors' Addresses
Omprakash Gnawali
Stanford University
S255 Clark Center, 318 Campus Drive
Stanford, CA 94305
USA
Phone: +1 650 725 6086
Email: gnawali@cs.stanford.edu
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Philip Levis
Stanford University
358 Gates Hall, Stanford University
Stanford, CA 94305
USA
Email: pal@cs.stanford.edu
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