Internet Engineering Task Force (IETF) JP. Vasseur
Request for Comments: 7102 Cisco Systems, Inc.
Category: Informational January 2014
ISSN: 2070-1721
Terms Used in Routing for Low-Power and Lossy Networks
Abstract
This document provides a glossary of terminology used in routing
requirements and solutions for networks referred to as Low-Power and
Lossy Networks (LLNs). An LLN is typically composed of many embedded
devices with limited power, memory, and processing resources
interconnected by a variety of links. There is a wide scope of
application areas for LLNs, including industrial monitoring, building
automation (e.g., heating, ventilation, air conditioning, lighting,
access control, fire), connected home, health care, environmental
monitoring, urban sensor networks, energy management, assets
tracking, and refrigeration.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7102.
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RFC 7102 LLN Routing Terms January 2014
Copyright Notice
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Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Security Considerations .........................................7
4. Acknowledgements ................................................7
5. Informative References ..........................................7
1. Introduction
This document provides a glossary of terminology used in routing
requirements and solutions for networks referred to as Low-Power and
Lossy Networks (LLNs).
LLNs are typically composed of many embedded devices with limited
power, memory, and processing resources interconnected by a variety
of links, such as IEEE 802.15.4 or low-power Wi-Fi. There is a wide
scope of application areas for LLNs, including industrial monitoring,
building automation (heating, ventilation, air conditioning,
lighting, access control, fire), connected home, health care,
environmental monitoring, urban sensor networks, energy management,
assets tracking, and refrigeration.
Since these applications are usually highly specific (for example,
industrial automation, building automation, etc.), it is not uncommon
to see a number of disparate terms used to describe the same device
or functionality. Thus, in order to avoid confusion or
discrepancies, this document specifies the common terminology to be
used in all ROLL working group documents. The terms defined in this
document are used in [RFC5548], [RFC5673], [RFC5826], and [RFC5867].
Terminology specific to a particular application is out of the scope
of this document.
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It is expected that all routing documents defining requirements or
specifying solutions for LLN will use the common terminology
specified in this document. This document should be listed as an
informative reference.
2. Terminology
Actuator: A field device that controls a set of equipment. For
example, an actuator might control and/or modulate the flow of a
gas or liquid, control electricity distribution, perform a
mechanical operation, etc.
AMI: Advanced Metering Infrastructure. Makes use of Smart Grid
technologies. A canonical Smart Grid application is smart-
metering.
Channel: Radio frequency sub-band used to transmit a modulated signal
carrying packets.
Channel Hopping: A procedure by which field devices synchronously
change channels during operation.
Commissioning Tool: Any physical or logical device temporarily added
to the network for the express purpose of setting up the network
and device operational parameters. The commissioning tool can
also be temporarily added to the LLN for scheduled or unscheduled
maintenance.
Closed Loop Control: A procedure whereby a device controller controls
an actuator based on input information sensed by one or more field
devices.
Controller: A field device that can receive sensor input and
automatically change the environment in the facility by
manipulating digital or analog actuators.
DA: Distribution Automation. Part of Smart Grid. Encompasses
technologies for maintenance and management of electrical
distribution systems.
DAG: Directed Acyclic Graph. A directed graph with no directed
cycles (a graph formed by a collection of vertices and directed
edges where each edge connects one vertex to another, such that
there is no way to start at some vertex v and follow a sequence of
edges that eventually loops back to vertex v again).
Data sink: A device that collects data from nodes in an LLN.
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Downstream: Data direction traveling from outside of the LLN (e.g.,
traffic coming from a LAN, WAN, or the Internet) via an LLN Border
Router (LBR), or in general, "deeper" in the Directed Acyclic
Graph computed by the routing protocol.
Field Device: A field device is a physical device placed in the
network's operating environment (e.g., plant, urban area, or
home). Field devices include sensors and actuators as well as
routers and Low-Power and Lossy Network Border Routers (LBRs). A
field device is usually (but not always) a device with constrained
CPU, memory footprint, storage capacity, bandwidth, and sometimes
power (battery operated). At the time of writing, for the sake of
illustration, a typical sensor or actuator would have a few
Kilobytes of RAM, a few dozens of Kilobytes of ROM/Flash memory, a
8-/16-/32-bit microcontroller, and communication capabilities
ranging from a few kbits/s to a few hundred kbits/s. Although
continuous improvement of hardware and software technologies is
expected, such devices will likely continue to be seen as
resource-constrained devices compared to computers and routers
used in the rest of the Internet.
Flash Memory: non-volatile memory that can be re-programmed.
FMS: Facility Management System. A global term applied across all
the vertical designations within a building, including heating,
ventilation, and air conditioning (also referred to as HVAC),
fire, security, lighting, and elevator control.
HART: Highway Addressable Remote Transducer. A group of
specifications for industrial process and control devices
administered by the HART Foundation (see [HART]). The latest
version for the specifications is HART7, which includes the
additions for WirelessHART.
HVAC: Heating, Ventilation, and Air Conditioning. A term applied to
mechanisms used to maintain the comfort level of an internal
space.
ISA: International Society of Automation. An ANSI accredited
standards-making society. ISA100 is an ISA committee whose
charter includes defining a family of standards for industrial
automation. [ISA100.11a] is a working group within ISA100 that is
working on a standard for monitoring and non-critical process-
control applications.
LAN: Local Area Network.
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LBR: Low-Power and Lossy Network Border Router. A device that
connects the Low-Power and Lossy Network to another routing domain
such as a LAN, a WAN, or the Internet where a different routing
protocol may be in operation. The LBR acts as a routing device
and may possibly host other functions such as data collector or
aggregator.
LLN: Low-Power and Lossy Network. Typically composed of many
embedded devices with limited power, memory, and processing
resources interconnected by a variety of links, such as IEEE
802.15.4 or low-power Wi-Fi. There is a wide scope of application
areas for LLNs, including industrial monitoring, building
automation (HVAC, lighting, access control, fire), connected home,
health care, environmental monitoring, urban sensor networks,
energy management, assets tracking, and refrigeration.
MP2P: Multipoint-to-Point. Used to describe a particular traffic
pattern (e.g., MP2P flows collecting information from many nodes
flowing upstream towards a collecting sink or an LBR).
MAC: Medium Access Control. Refers to algorithms and procedures used
by the data link layer to coordinate use of the physical layer.
Non-Sleepy Node: A node that always remains in a fully powered-on
state (i.e., always awake) where it has the capability to perform
communication.
Open Loop Control: A process whereby a plant operator manually
manipulates an actuator over the network where the decision is
influenced by information sensed by field devices.
PER: Packet Error Rate. A ratio of the number of unusable packets
(not received at all or received in error, even after any
applicable error correction has been applied) to the total number
of packets that would have been received in the absence of errors.
P2P: Point To Point. Refers to traffic exchanged between two nodes
(regardless of the number of hops between the two nodes).
P2MP: Point-to-Multipoint. Refers to traffic between one node and a
set of nodes. This is similar to the P2MP concept in Multicast or
MPLS Traffic Engineering ([RFC4461]and [RFC4875]). A common use
case for the Routing Protocol for Low-Power and Lossy Networks
(RPL) involves P2MP flows from or through a DAG root outward
towards other nodes contained in the DAG.
RAM: Random Access Memory. A volatile memory.
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RFID: Radio Frequency IDentification.
ROM: Read-Only Memory.
ROLL: Routing Over Low-Power and Lossy Networks.
RPL: An IPv6 Routing Protocol for Low-Power and Lossy Networks that
provides a mechanism whereby multipoint-to-point traffic from
devices inside the LLN towards a central control point as well as
point-to-multipoint traffic from the central control point to the
devices inside the LLN are supported. RPL also supports point-to-
point traffic between any arbitrary nodes in the LLN.
RPL Domain: A collection of RPL routers under the control of a single
administration. The boundaries of routing domains are defined by
network management by setting some links to be exterior, or inter-
domain, links.
Schedule: An agreed execution, wake-up, transmission, reception,
etc., timetable between two or more field devices.
Sensor: A device that measures a physical quantity and converts it to
an analog or digital signal that can be read by a program or a
user. Sensed data can be of many types: electromagnetic (e.g.,
current, voltage, power, or resistance), mechanical (e.g.,
pressure, flow, liquid density, or humidity), chemical (e.g.,
oxygen or carbon monoxide), acoustic (e.g., noise or ultrasound),
etc.
Sleepy Node: A node that may sometimes go into a sleep mode (i.e., go
into a low-power state to conserve power) and temporarily suspend
protocol communication. When not in sleep mode, the sleepy node
is in a fully powered-on state where it has the capability to
perform communication.
Smart Grid: A broad class of applications to network and automate
utility infrastructure.
Timeslot: A fixed time interval that may be used for the transmission
or reception of a packet between two field devices. A timeslot
used for communications is associated with a slotted-link.
Upstream: Data direction traveling from the LLN via the LBR to
outside of the LLN (LAN, WAN, or Internet) or generally closer to
the root of the DAG computed by the routing protocol.
WAN: Wide Area Network.
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3. Security Considerations
Since this document specifies terminology and does not specify new
procedures or protocols, it raises no new security issues.
4. Acknowledgements
The authors would like to thank Christian Jacquenet, Tim Winter,
Pieter De Mil, David Meyer, Mukul Goyal, and Abdussalam Baryun for
their valuable feedback.
5. Informative References
[HART] HART Communication Foundation, <http://www.hartcomm.org>.
[ISA100.11a]
ISA, "Wireless systems for industrial automation: Process
control and related applications", ISA 100.11a, May 2008,
<http://www.isa.org/Community/
SP100WirelessSystemsforAutomation>.
[RFC4461] Yasukawa, S., Ed., "Signaling Requirements for Point-to-
Multipoint Traffic-Engineered MPLS Label Switched Paths
(LSPs)", RFC 4461, April 2006.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. Yasukawa,
Ed., "Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5548] Dohler, M., Ed., Watteyne, T., Ed., Winter, T., Ed., and D.
Barthel, Ed., "Routing Requirements for Urban Low-Power and
Lossy Networks", RFC 5548, May 2009.
[RFC5673] Pister, K., Ed., Thubert, P., Ed., Dwars, S., and T.
Phinney, "Industrial Routing Requirements in Low-Power and
Lossy Networks", RFC 5673, October 2009.
[RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation
Routing Requirements in Low-Power and Lossy Networks", RFC
5826, April 2010.
[RFC5867] Martocci, J., Ed., De Mil, P., Riou, N., and W. Vermeylen,
"Building Automation Routing Requirements in Low-Power and
Lossy Networks", RFC 5867, June 2010.
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Author's Address
JP. Vasseur
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
US
EMail: jpv@cisco.com
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