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RFC 7547

Informational
Pages: 44
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Management of Networks with Constrained Devices: Problem Statement and Requirements

Part 1 of 2, p. 1 to 16
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Internet Engineering Task Force (IETF)                     M. Ersue, Ed.
Request for Comments: 7547                                Nokia Networks
Category: Informational                                     D. Romascanu
ISSN: 2070-1721                                                    Avaya
                                                        J. Schoenwaelder
                                                Jacobs University Bremen
                                                              U. Herberg
                                                                May 2015


            Management of Networks with Constrained Devices:
                   Problem Statement and Requirements

Abstract

   This document provides a problem statement, deployment and management
   topology options, as well as requirements addressing the different
   use cases of the management of networks where constrained devices are
   involved.

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/rfc7547.

Page 2 
Copyright Notice

   Copyright (c) 2015 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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Overview ...................................................3
      1.2. Terminology ................................................4
      1.3. Network Types and Characteristics in Focus .................5
      1.4. Constrained Device Deployment Options ......................9
      1.5. Management Topology Options ...............................10
      1.6. Managing the Constrainedness of a Device or Network .......10
      1.7. Configuration and Monitoring Functionality Levels .........13
   2. Problem Statement ..............................................14
   3. Requirements on the Management of Networks with
      Constrained Devices ............................................16
      3.1. Management Architecture/System ............................18
      3.2. Management Protocols and Data Models ......................22
      3.3. Configuration Management ..................................25
      3.4. Monitoring Functionality ..................................27
      3.5. Self-Management ...........................................32
      3.6. Security and Access Control ...............................33
      3.7. Energy Management .........................................35
      3.8. Software Distribution .....................................37
      3.9. Traffic Management ........................................37
      3.10. Transport Layer ..........................................39
      3.11. Implementation Requirements ..............................40
   4. Security Considerations ........................................41
   5. Informative References .........................................42
   Acknowledgments ...................................................44
   Authors' Addresses ................................................44

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1.  Introduction

1.1.  Overview

   Constrained devices (also known as sensors, smart objects, or smart
   devices) with limited CPU, memory, and power resources can be
   connected to a network.  It might be based on unreliable or lossy
   channels, it may use wireless technologies with limited bandwidth and
   a dynamic topology, or it may need the service of a gateway or proxy
   to connect to the Internet.  In other scenarios, the constrained
   devices can be connected to a unconstrained network using off-the-
   shelf protocol stacks.

   Constrained devices might be in charge of gathering information in
   diverse settings including natural ecosystems, buildings, and
   factories and sending the information to one or more server stations.
   Constrained devices may also work under severe resource constraints
   such as limited battery and computing power, little memory and
   insufficient wireless bandwidth, and communication capabilities.  A
   central entity, e.g., a base station or controlling server, might
   have more computational and communication resources and can act as a
   gateway between the constrained devices and the application logic in
   the core network.

   Today, constrained devices of diverse size and with different
   resources and capabilities are being connected.  Mobile personal
   gadgets, building-automation devices, cellular phones, machine-to-
   machine (M2M) devices, etc., benefit from interacting with other
   "things" in the near or somewhere in the Internet.  With this the
   Internet of Things (IoT) becomes a reality, built up of uniquely
   identifiable objects (things).  And over the next decade, this could
   grow to trillions of constrained devices and will greatly increase
   the Internet's size and scope.

   Network management is characterized by monitoring network status,
   detecting faults (and inferring their causes), setting network
   parameters, and carrying out actions to remove faults, maintain
   normal operation, and improve network efficiency and application
   performance.  The traditional network monitoring application
   periodically collects information from a set of managed network
   elements, it processes the data, and it presents the results to the
   network management users.  Constrained devices, however, often have
   limited power, have low transmission range, and might be unreliable.
   They might also need to work in hostile environments with advanced
   security requirements or need to be used in harsh environments for a
   long time without supervision.  Due to such constraints, the

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   management of a network with constrained devices faces a different
   type of challenges compared to the management of a traditional IP
   network.

   The IETF has already done substantial standardization work to enable
   communication in IP networks and to manage such networks as well as
   the manifold types of nodes in these networks [RFC6632].  However,
   the IETF so far has not developed any specific technologies for the
   management of constrained devices and the networks comprised by
   constrained devices.  IP-based sensors or constrained devices in such
   an environment (i.e., devices with very limited memory, CPU, and
   energy resources) nowadays use application-layer protocols in an ad
   hoc manner to do simple resource management and monitoring.

   This document provides a problem statement and lists requirements for
   the different use cases of management of a network with constrained
   devices.  Sections 1.3 and 1.5 describe different topology options
   for the networking and management of constrained devices.  Section 2
   provides a problem statement on the issue of the management of
   networked constrained devices.  Section 3 lists requirements on the
   management of applications and networks with constrained devices.
   Note that the requirements listed in Section 3 have been separated
   from the context in which they may appear.  Depending on the concrete
   circumstances, an implementer may decide to address a certain
   relevant subset of the requirements.

   The use cases in the context of networks with constrained devices can
   be found in [RFC7548].  This document provides a list of objectives
   for discussions and does not aim to be a strict requirements document
   for all use cases.  In fact, there likely is not a single solution
   that works equally well for all the use cases.

1.2.  Terminology

   Concerning constrained devices and networks, this document generally
   builds on the terminology defined in [RFC7228], where the terms
   "constrained device", "constrained network", and others are defined.

   Additionally, the following terms are used throughout:

   AMI:   (Advanced Metering Infrastructure) A system including
          hardware, software, and networking technologies that measures,
          collects, and analyzes energy use and that communicates with a
          hierarchically deployed network of metering devices, either on
          request or on a schedule.

   C0:    Class 0 constrained device as defined in Section 3 of
          [RFC7228].

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   C1:    Class 1 constrained device as defined in Section 3 of
          [RFC7228].

   C2:    Class 2 constrained device as defined in Section 3 of
          [RFC7228].

   Network of Constrained Devices:  A network to which constrained
          devices are connected that may or may not be a constrained
          network (see [RFC7228] for the definition of the term
          constrained network).

   M2M:   (Machine to Machine) The automatic data transfer between
          devices of different kinds.  In M2M scenarios, a device (such
          as a sensor or meter) captures an event, which is relayed
          through a network (wireless, wired, or hybrid) to an
          application.

   MANET: (Mobile Ad Hoc Network [RFC2501]) A self-configuring and
          infrastructureless network of mobile devices connected by
          wireless technologies.

   Smart Grid:  An electrical grid that uses communication technologies
          to gather and act on information in an automated fashion to
          improve the efficiency, reliability, and sustainability of the
          production and distribution of electricity.

   Smart Meter:  An electrical meter in the context of a smart grid.

   For a detailed discussion on the constrained networks as well as
   classes of constrained devices and their capabilities, please see
   [RFC7228].

1.3.  Network Types and Characteristics in Focus

   In this document, we differentiate the following types of networks
   concerning their transport and communication technologies:

   (Note that a network in general can involve constrained and
   unconstrained devices.)

   1.  Wireline unconstrained networks, e.g., an Ethernet LAN with
       constrained and unconstrained devices involved.

   2.  A combination of wireline and wireless networks, possibly with a
       multi-hop connectivity between constrained devices, utilizing
       dynamic routing in both the wireless and wireline portions of the
       network.  Such networks usually support highly distributed
       applications with many nodes (e.g., environmental monitoring) and

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       tend to deal with large-scale multipoint-to-point (MP2P) systems.
       Wireless Mesh Networks (WMNs), as a specific variant, use off-
       the-shelf radio technology such as Wi-Fi, WiMAX, and cellular
       3G/4G.  WMNs are reliable based on the redundancy they offer and
       have often a more planned deployment to provide dynamic and cost
       effective connectivity over a certain geographic area.

   3.  A combination of wireline and wireless networks with point-to-
       point (P2P) or point-to-multipoint (P2MP) communication generally
       with single-hop connectivity to constrained devices, utilizing
       static routing over the wireless network.  Such networks support
       short-range, P2P, low-data-rate, source-to-sink types of
       applications, such as RFID systems, light switches, fire/smoke
       detectors, and home appliances.  This type of network also
       supports confined short-range spaces such as a home, a factory, a
       building, or the human body.  [IEEE802.15.1] (Bluetooth) and
       [IEEE802.15.4] are well-known examples of applicable standards
       for such networks.  By using 6LoWPANs (IPv6 over Low-Power
       Wireless Personal Area Networks) [RFC4919] and RPL (Routing
       Protocol for Low-Power and Lossy Networks) [RFC6550] on top of
       IEEE 802.15.4, multi-hop connectivity and dynamic routing can be
       achieved.  With RPL, the IETF has specified a proactive "route-
       over" architecture where routing and forwarding is implemented at
       the network layer.  The protocol provides a mechanism whereby
       MP2P, P2MP, and P2P traffic are supported.

   4.  Self-configuring infrastructureless networks of mobile devices
       (e.g., MANET) are a particular type of network connected by
       wireless technologies.  Infrastructureless networks are mostly
       based on P2P communications of devices moving independently in
       any direction and changing the links to other devices frequently.
       Such devices do act as a router to forward traffic unrelated to
       their own use.

   Wireline unconstrained networks with constrained and unconstrained
   devices are mainly used for specific applications like Building
   Automation or Infrastructure Monitoring.  Wireline and wireless
   networks with multi-hop or P2MP connectivity are used, e.g., for
   environmental monitoring as well as transport and mobile
   applications.

   Furthermore, different network characteristics are determined by
   multiple dimensions: dynamicity of the topology, bandwidth, and loss
   rate.  In the following, each dimension is explained, and networks in
   scope for this document are outlined:

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   Network Topology:

   The topology of a network can be represented as a graph, with edges
   (i.e., links) and vertices (routers and hosts).  Examples of
   different topologies include "star" topologies (with one central node
   and multiple nodes in one-hop distance), tree structures (with each
   node having exactly one parent), directed acyclic graphs (with each
   node having one or more parents), clustered topologies (where one or
   more "cluster heads" are responsible for a certain area of the
   network), mesh topologies (fully distributed), etc.

   Management protocols may take advantage of specific network
   topologies, for example, by distributing large-scale management tasks
   amongst multiple distributed network management stations (e.g., in
   case of a mesh topology), or by using a hierarchical management
   approach (e.g., in case of a tree or clustered topology).  These
   different management topology options are described in Section 1.6.

   Note that in certain network deployments, such as community ad hoc
   networks (see the use case "Community Network Applications" in
   [RFC7548]), the topology is not preplanned; thus, it may be unknown
   for management purposes.  In other use cases, such as industrial
   applications (see the use case "Industrial Applications" in
   [RFC7548]), the topology may be designed in advance and therefore
   taken advantage of when managing the network.

   Dynamicity of the network topology:

   The dynamicity of the network topology determines the rate of change
   of the graph as a function of time.  Such changes can occur due to
   different factors, such as mobility of nodes (e.g., in MANETs or
   cellular networks), duty cycles (for low-power devices enabling their
   network interface only periodically to transmit or receive packets),
   or unstable links (in particular wireless links with strongly
   fluctuating link quality).

   Examples of different levels of dynamicity of the topology are
   Ethernets (with typically a very static topology) on the one side,
   and Low-power and Lossy Networks (LLNs) on the other side.  LLNs
   nodes are often duty-cycled and operate on unreliable wireless links
   and are potentially mobile (e.g., for sensor networks).

   The more dynamic the topology is, the more have routing, transport
   and application-layer protocols to cope with interrupted connectivity
   and/or longer delays.  For example, management protocols (with a
   given underlying transport protocol) that expect continuous session
   flows without changes of routes during a communication flow, may fail
   to operate.

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   Networks with a very low dynamicity (e.g., Ethernet) with no or
   infrequent topology changes (e.g., less than once every 30 minutes),
   are in the scope of this document if they are used with constrained
   devices (see, e.g., the use case "Building Automation" in [RFC7548]).

   Traffic flows:

   The traffic flow in a network determines from which sources data
   traffic is sent to which destinations in the network.  Several
   different traffic flows are defined in [RFC7102], including P2P,
   MP2P, and P2MP flows as:

   o  P2P: Point-to-point refers to traffic exchanged between two nodes
      (regardless of the number of hops between the two nodes).

   o  P2MP: Point-to-multipoint traffic refers to traffic between one
      node and a set of nodes.  This is similar to the P2MP concept in
      Multicast or MPLS Traffic Engineering.

   o  MP2P: Multipoint-to-point is used to describe a particular traffic
      pattern (e.g., MP2P flows collecting information from many nodes
      flowing inwards towards a collecting sink).

   If one of these traffic patterns is predominant in a network,
   protocols (routing, transport, application) may be optimized for the
   specific traffic flow.  For example, in a network with a tree
   topology and MP2P traffic, collection tree protocols are efficient to
   send data from the leaves of the tree to the root of the tree, via
   each node's parent.

   Bandwidth:

   The bandwidth of the network is the amount of data that can be sent
   per unit of time between two communication endpoints.  It is usually
   determined by the link with the minimum bandwidth on the path from
   the source to the destination of data packets.  The bandwidth in
   networks can range from a few kilobytes per second (such as on some
   IEEE 802.15.4 link layers) to many gigabytes per second (e.g., on
   fiber optics).

   For management purposes, the management protocol typically requires
   the sending of information between the network management station and
   the clients, for monitoring or control purposes.  If the available
   bandwidth is insufficient for the management protocol, packets will
   be buffered and eventually dropped; thus, management is not possible
   with such a protocol.

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   Networks without bandwidth limitation (e.g., Ethernet) are in the
   scope of this document if they are used with constrained devices (see
   the use case "Building Automation" in [RFC7548]).

   Loss rate:

   The loss rate (or bit error rate) is the number of bit errors divided
   by the total number of bits transmitted.  For wired networks, loss
   rates are typically extremely low, e.g., around 10^-12 or 10^-13 for
   the latest 10 Gbit Ethernet.  For wireless networks, such as IEEE
   802.15.4, the bit error rate can be as high as 10^-1 to 1 in case of
   interferences.  Even when using a reliable transport protocol,
   management operations can fail if the loss rate is too high, unless
   they are specifically designed to cope with these situations.

1.4.  Constrained Device Deployment Options

   We differentiate the following deployment options for the constrained
   devices:

   o  A network of constrained devices that communicate with each other,

   o  Constrained devices that are connected directly to an IP network,

   o  A network of constrained devices that communicate with a gateway
      or proxy with more communication capabilities possibly acting as a
      representative of the device to entities in the unconstrained
      network,

   o  Constrained devices that are connected to the Internet or an IP
      network via a gateway/proxy,

   o  A hierarchy of constrained devices, e.g., a network of C0 devices
      connected to one or more C1 devices -- connected to one or more C2
      devices -- connected to one or more gateways -- connected to some
      application servers or NMS, and

   o  The possibility of device grouping (possibly in a dynamic manner)
      such as that the grouped devices can act as one logical device at
      the edge of the network and one device in this group can act as
      the managing entity.

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1.5.  Management Topology Options

   We differentiate the following options for the management of networks
   of constrained devices:

   o  A network of constrained devices managed by one central manager.
      A logically centralized management might be implemented in a
      hierarchical fashion for scalability and robustness reasons.  The
      manager and the management application logic might have a gateway/
      proxy in between or might be on different nodes in different
      networks, e.g., management application running on a cloud server.

   o  Distributed management, where a network of constrained devices is
      managed by more than one manager.  Each manager controls a
      subnetwork and may communicate directly with other manager
      stations in a cooperative fashion.  The distributed management may
      be weakly distributed, where functions are broken down and
      assigned to many managers dynamically, or strongly distributed,
      where almost all managed things have embedded management
      functionality and explicit management disappears, which usually
      comes with the price that the strongly distributed management
      logic now needs to be managed.

   o  Hierarchical management, where a hierarchy of networks with
      constrained devices are managed by the managers at their
      corresponding hierarchy level.  That is, each manager is
      responsible for managing the nodes in its subnetwork.  It passes
      information from its subnetwork to its higher-level manager and
      disseminates management functions received from the higher-level
      manager to its subnetwork.  Hierarchical management is essentially
      a scalability mechanism, logically the decision-making may be
      still centralized.

1.6.  Managing the Constrainedness of a Device or Network

   The capabilities of a constrained device or network and the
   constrainedness thereof influence and have an impact on the
   requirements for the management of such a network or devices.

   Note that the list below gives examples and does not claim
   completeness.

   A constrained device:

   o  might only support an unreliable (e.g., lossy) radio link, i.e.,
      the client and server of a management protocol need to gracefully
      handle incomplete command exchanges or missing commands.

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   o  might only be able to go online from time to time, where it is
      reachable, i.e., a command might be necessary to repeat after a
      longer timeout or the timeout value with which one endpoint waits
      on a response needs to be sufficiently high.

   o  might only be able to support a limited operating time (e.g.,
      based on the available battery) or may behave as 'sleepy
      endpoints', setting their network links to a disconnected state
      during long periods of time, i.e., the devices need to economize
      their energy usage with suitable mechanisms and the managing
      entity needs to monitor and control the energy status of the
      constrained devices it manages.

   o  might only be able to support one simple communication protocol,
      i.e., the management protocol needs to be possible to downscale
      from constrained (C2) to very constrained (C0) devices with
      modular implementation and a very basic version with just a few
      simple commands.

   o  might only be able to support a communication protocol, which is
      not IP based.

   o  might only be able to support limited or no user and/or transport
      security, i.e., the management system needs to support a less-
      costly and simple but sufficiently secure authentication
      mechanism.

   o  might not be able to support compression and decompression of
      exchanged data based on limited CPU power, i.e., an intermediary
      entity which is capable of data compression should be able to
      communicate with both, devices that support data compression
      (e.g., C2) and devices that do not support data compression (e.g.,
      C1 and C0).

   o  might only be able to support a simple encryption, i.e., it would
      be beneficial if the devices use cryptographic algorithms that are
      supported in hardware and the encryption used is efficient in
      terms of memory and CPU usage.

   o  might only be able to communicate with one single managing entity
      and cannot support the parallel access of many managing entities.

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   o  might depend on a self-configuration feature, i.e., the managing
      entity might not know all devices in a network and the device
      needs to be able to initiate connection setup for the device
      configuration.

   o  might depend on self- or neighbor-monitoring features, i.e., the
      managing entity might not be able to monitor all devices in a
      network continuously.

   o  might only be able to communicate with its neighbors, i.e., the
      device should be able to get its configuration from a neighbor.

   o  might only be able to support parsing of data models with limited
      size, i.e., the device data models need to be compact containing
      the most necessary data and if possible parsable as a stream.

   o  might only be able to support a limited or no-failure detection,
      i.e., the managing entity needs to handle the situation, where a
      failure does not get detected or gets detected late gracefully,
      e.g., with asking repeatedly.

   o  might only be able to support the reporting of just one or a
      limited set failure types.

   o  might only be able to support a limited set of notifications,
      possible only an "I am alive." message.

   o  might only be able to support a soft-reset from failure recovery.

   o  might possibly generate a large amount of redundant reporting
      data, i.e., the intermediary management entity (see [RFC7252])
      should be able to filter and aggregate redundant data.

   A network of constrained devices:

   o  might only support an unreliable (e.g., lossy) radio link, i.e.,
      the client and server of a management protocol need to repeat
      commands as necessary or gracefully ignore incomplete commands.

   o  might be necessary to manage based on multicast communication,
      i.e., the managing entity needs to be prepared to configure many
      devices at once based on the same data model.

   o  might have a very large topology supporting 10,000 or more nodes
      for some applications and as such node naming is a specific issue
      for constrained networks.

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   o  needs to support self-organization, i.e., given the large number
      of nodes and their potential placement in hostile locations and
      frequently changing topology, manual configuration of nodes is
      typically not feasible.  As such, the network would benefit from
      the ability to reconfigure itself so that it can continue to
      operate properly and support reliable connectivity.

   o  might need a management solution that is energy efficient, using
      as little wireless bandwidth as possible since communication is
      highly energy demanding.

   o  needs to support localization schemes to determine the location of
      devices since the devices might be moving and location information
      is important for some applications.

   o  needs a management solution that is scalable as the network may
      consist of thousands of nodes and may need to be extended
      continuously.

   o  needs to provide fault tolerance.  Faults in network operation
      including hardware and software errors or failures detected by the
      transport protocol should be handled smoothly.  In such a case, it
      should be possible to run the protocol at a reduced level but
      avoid failing completely.  For example, self-monitoring mechanisms
      or graceful degradation of features can be used to provide fault
      tolerance.

   o  might require new management capabilities, for example, network
      coverage information and a constrained device power distribution
      map.

   o  might require a new management function for data management, since
      the type and amount of data collected in constrained networks is
      different from those of the traditional networks.

   o  might also need energy-efficient key management.

1.7.  Configuration and Monitoring Functionality Levels

   Devices often differ significantly on the level of configuration
   management support they provide.  This document classifies the
   configuration management functionality as follows:

   CL0:  Devices are preconfigured and allow no runtime configuration
         changes.  Configuration parameters are often hard coded and
         compiled directly into the firmware image.

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   CL1:  Devices have explicit configuration objects.  However, changes
         require a restart of the device to take effect.

   CL2:  Devices allow management systems to replace the entire
         configuration (or predetermined subsets) in bulk.
         Configuration changes take effect by soft-restarts of the
         system (or subsystems).

   CL3:  Devices allow management systems to modify configuration
         objects without bulk replacements and changes take effect
         immediately.

   CL4:  Devices support multiple configuration datastores and they
         might distinguish between the currently running and the next
         startup configuration.

   CL5:  Devices support configuration datastore locking and device-
         local configuration change transactions, i.e., either all
         configuration changes are applied or none of them are.

   CL6:  Devices support configuration change transactions across
         devices.

   This document defines a classification of devices with regard to
   different levels of monitoring support.  In general, a device may be
   in several of the levels listed below:

   ML0:  Devices push predefined monitoring data.

   ML1:  Devices allow management systems to pull predefined monitoring
         data.

   ML2:  Devices allow management systems to pull user-defined filtered
         subsets of monitoring data.

   ML3:  Devices are able to locally process monitoring data in order to
         detect threshold crossings or to aggregate data.

   At the time of this writing, constrained devices often implement a
   combination of one of CL0-CL2 with one of ML0-ML1.

2.  Problem Statement

   The terminology for the "Internet of Things" is still nascent, and
   depending on the network type or layer in focus, diverse technologies
   and terms are in use.  Common to all these considerations is the
   "Things" or "Objects" are supposed to have physical or virtual
   identities using interfaces to communicate.  In this context, we need

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   to differentiate between the constrained and smart devices identified
   by an IP address compared to virtual entities such as Smart Objects,
   which can be identified as a resource or a virtual object by using a
   unique identifier.  Furthermore, the smart devices usually have
   limited memory and CPU power as well as aim to be self-configuring
   and easy to deploy.

   However, the constraints of the network nodes require a rethinking of
   the protocol characteristics concerning power consumption,
   performance, bandwidth consumption, memory, and CPU usage.  As such,
   there is a demand for protocol simplification, energy-efficient
   communication, less CPU usage, and a smaller memory footprint.

   On the application layer, the IETF is already developing protocols
   like the Constrained Application Protocol (CoAP) [RFC7252] enabling
   the communication of constrained devices and networks, e.g., for
   smart energy applications or home automation environments.  In fact,
   the deployment of such an environment involves many, in some
   scenarios up to million, constrained devices (e.g., smart meters),
   which produce a large amount of data.  This data needs to be
   collected, filtered, and preprocessed for further use in diverse
   services.

   Considering the high number of nodes to deploy, one has to think
   about the manageability aspects of the smart devices and plan for
   easy deployment, configuration, and management of the networks of
   constrained devices as well as the devices themselves.  Consequently,
   seamless monitoring and self-configuration of such network nodes
   becomes more and more imperative.  Self-configuration and self-
   management are already a reality in the standards of some
   organizations such as 3GPP.  To introduce self-configuration of smart
   devices successfully, a device-initiated connection establishment is
   often required.

   A simple and efficient application-layer protocol, such as CoAP, is
   essential to address the issue of efficient object-to-object
   communication and information exchange.  Such an information exchange
   should be done based on interoperable data models to enable the
   exchange and interpretation of diverse application- and management-
   related data.

   In an ideal world, we would have only one network management protocol
   for monitoring, configuration, and exchanging management data,
   independently of the type of the network (e.g., smart grid, wireless
   access, or core network).  Furthermore, it would be desirable to
   derive the basic data models for constrained devices from the core
   models used today to enable reuse of functionality and end-to-end
   information exchange.  However, the current management protocols seem

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   to be too heavyweight compared to the capabilities the constrained
   devices have and are not applicable directly for use in a network of
   constrained devices.  Furthermore, the data models addressing the
   requirements of such smart devices need yet to be designed.

   So far, the IETF has not developed any specific technologies for the
   management of constrained devices and the networks comprised by
   constrained devices.  IP-based sensors or constrained devices in such
   an environment, i.e., today, devices with very limited memory and CPU
   resources use, e.g., application-layer protocols to do simple
   resource management and monitoring.  This might be sufficient for
   some basic cases; however, there is a need to reconsider the network
   management mechanisms based on the new, changed, and reduced
   requirements coming from smart devices and the network of such
   constrained devices.  Although it is questionable whether we can take
   the same comprehensive approach we use in an IP network and use it
   for the management of constrained devices.  Hence, the management of
   a network with constrained devices is necessarily designed in a
   simplified and less complex manner.

   As Section 1.6 highlights, there are diverse characteristics of
   constrained devices or networks, which stem from their
   constrainedness and therefore have an impact on the requirements for
   the management of such a network with constrained devices.  The use
   cases discussed in [RFC7548] show that the requirements on
   constrained networks are manifold and need to be analyzed from
   different angles, e.g., concerning the design of the management
   architecture, the selection of the appropriate protocol features, as
   well as the specific issues that are new in the context of
   constrained devices.  Examples of such issues are careful management
   of scarce energy resources, the necessity for self-organization and
   self-management of such devices but also the implementation
   considerations to enable the use of common communication technologies
   on a constrained hardware in an efficient manner.  For an exhaustive
   list of issues and requirements that need to be addressed for the
   management of a network with constrained devices, please see Sections
   1.6 and 3.



(page 16 continued on part 2)

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