





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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Copyright Notice

   Copyright (c) 2014 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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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