Internet Engineering Task Force M. Ersue, Ed. Internet-Draft Nokia Solutions and Networks Intended status: Informational D. Romascanu Expires: April 28, 2014 Avaya J. Schoenwaelder Jacobs University Bremen October 25, 2013 Management of Networks with Constrained Devices: Problem Statement and Requirements draft-ersue-opsawg-coman-probstate-reqs-00 Abstract This document provides a problem statement, deployment and management topology options as well as the requirements for the management of networks where constrained devices are involved. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 28, 2014. Copyright Notice Copyright (c) 2013 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 Ersue, et al. Expires April 28, 2014 [Page 1] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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. Networks Types and Characteristics in Focus . . . . . . . 5 1.4. Constrained Device Deployment Options . . . . . . . . . . 9 1.5. Management Topology Options . . . . . . . . . . . . . . . 9 1.6. Managing the Constrainedness of a Device or Network . . . 10 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 14 3. Requirements on the Management of Networks with Constrained Devices . . . . . . . . . . . . . . . . . . . . . 16 3.1. Management Architecture/System . . . . . . . . . . . . . . 16 3.2. Management protocols and data model . . . . . . . . . . . 21 3.3. Configuration management . . . . . . . . . . . . . . . . . 24 3.4. Monitoring functionality . . . . . . . . . . . . . . . . . 26 3.5. Self-management . . . . . . . . . . . . . . . . . . . . . 31 3.6. Security and Access Control . . . . . . . . . . . . . . . 32 3.7. Energy Management . . . . . . . . . . . . . . . . . . . . 34 3.8. SW Distribution . . . . . . . . . . . . . . . . . . . . . 36 3.9. Traffic management . . . . . . . . . . . . . . . . . . . . 36 3.10. Transport Layer . . . . . . . . . . . . . . . . . . . . . 38 3.11. Implementation Requirements . . . . . . . . . . . . . . . 39 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 5. Security Considerations . . . . . . . . . . . . . . . . . . . 42 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 43 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 44 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 45 8.1. Normative References . . . . . . . . . . . . . . . . . . . 45 8.2. Informative References . . . . . . . . . . . . . . . . . . 45 Appendix A. Related Development in other Bodies . . . . . . . . . 47 A.1. ETSI TC M2M . . . . . . . . . . . . . . . . . . . . . . . 47 A.2. OASIS . . . . . . . . . . . . . . . . . . . . . . . . . . 48 A.3. OMA . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 A.4. IPSO Alliance . . . . . . . . . . . . . . . . . . . . . . 49 Appendix B. Related Research Projects . . . . . . . . . . . . . . 51 Appendix C. Open issues . . . . . . . . . . . . . . . . . . . . . 52 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 53 D.1. draft-ersue-constrained-mgmt-03 - draft-ersue-opsawg-coman-probstate-reqs-00 . . . . . . . . 53 D.2. draft-ersue-constrained-mgmt-02-03 . . . . . . . . . . . . 53 D.3. draft-ersue-constrained-mgmt-01-02 . . . . . . . . . . . . 54 D.4. draft-ersue-constrained-mgmt-00-01 . . . . . . . . . . . . 55 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 56 Ersue, et al. Expires April 28, 2014 [Page 2] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 1. Introduction 1.1. Overview Small devices with limited CPU, memory, and power resources, so called constrained devices (aka. sensor, smart object, or smart device) can constitute a network. Such a network of constrained devices itself may be constrained or challenged, e.g. with unreliable or lossy channels, wireless technologies with limited bandwidth and a dynamic topology, needing the service of a gateway or proxy to connect to the Internet. In other scenarios, the constrained devices can be connected to a non-constrained 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 send the information to one or more server stations. Constrained devices may 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 diverse size of small devices 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 build 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 management application periodically collects information from a set of elements that are needed to manage, processes the data, and presents them to the network management users. Constrained devices, however, often have limited power, 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 management of a network with constrained devices offers different Ersue, et al. Expires April 28, 2014 [Page 3] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 type of challenges compared to the management of a traditional IP network. The IETF has already done a lot of standardization work to enable the communication in IP networks and to manage such networks as well as the manifold type 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 and CPU resources, use today application-layer protocols in an ad-hoc manner to do simple resource management and monitoring. This document provides a problem statement and lists the requirements for the management of a network with constrained devices. Section 1.3 and Section 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 in Section 3 need to be seen as standalone requirements, where different implementer may decide to realize a different set of them. The use cases in the context of networks with constrained devices can be found in the companion document [COM-US]. 1.2. Terminology Concerning constrained devices and networks this document generally builds on the terminology defined in [I-D.ietf-lwig-terminology], where the terms Constrained Device, Constrained Network, etc. are defined. The following terms are additionally used throughout this documentation: AMI: (Advanced Metering Infrastructure) A system including hardware, software, and networking technologies that measures, collects, and analyzes energy usage, and 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 [I-D.ietf-lwig-terminology]. Ersue, et al. Expires April 28, 2014 [Page 4] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 C1: Class 1 constrained device as defined in Section 3. of [I-D.ietf-lwig-terminology]. C2: Class 2 constrained device as defined in Section 3. of [I-D.ietf-lwig-terminology]. Network of Constrained Devices: A network to which constrained devices are connected that may or may not be a Constrained Network (see [I-D.ietf-lwig-terminology] for the definition of the term Constrained Network). M2M: (Machine to Machine) stands for the automatic data transfer between devices of different kind. 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 Networks, 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 [I-D.ietf-lwig-terminology]. 1.3. Networks Types and Characteristics in Focus In this document we differentiate following type of networks concerning their transport and communication technologies: Note that a network in general can involve constrained and non- constrained devices. 1. Wireline non-constrained networks, e.g. an Ethernet-LAN with non- constrained and constrained devices involved. 2. A combination of wireline and wireless networks, which may or may not be mesh-based but have 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 tend to deal with large-scale Ersue, et al. Expires April 28, 2014 [Page 5] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 multipoint-to-point systems with massive data flows. Wireless Mesh Networks (WMN), 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 or point-to-multipoint communication generally with single- hop connectivity to constrained devices, utilizing static routing over the wireless network. Such networks support short-range, point-to-point, low-data-rate, source-to-sink type of applications such as RFID systems, light switches, fire and smoke detectors, and home appliances. This type of networks also support confined short-range spaces such as a home, a factory, a building, or the human body. IEEE 802.15.1 (Bluetooth) and IEEE 802.15.4 are well-known examples of applicable standards for such networks. 4. Mobile Adhoc networks (MANET) are self-configuring _infrastructureless_ networks of mobile devices connected by wireless technologies. MANETs are based on point-to-point communications of devices moving independently in any direction and changing the links to other devices frequently. MANET devices do act as a router to forward traffic unrelated to their own use. Wireline non-constrained networks are mainly used for specific applications like Building Automation or Infrastructure Monitoring. However, wireline and wireless networks with multi-hop or point-to- multipoint connectivity are especially in the interest of the analysis on the management of constrained devices in this document. 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: 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. Ersue, et al. Expires April 28, 2014 [Page 6] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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 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 [COM-US]), the topology is not pre-planned, and thus may be unknown for management purposes. In other use cases, such as industrial applications (see the use case "Industrial Applications" in [COM-US]), 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 per 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 often using duty cycles, operate on unreliable wireless links and are potentially mobile (e.g. for sensor networks). The more the topology is dynamic, the more routing, transport and application layer protocols have 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. 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-scope of this document if they are used with constrained devices (see e.g. the use case "Building Automation" in [COM-US]). 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 [I-D.ietf-roll-terminology], Ersue, et al. Expires April 28, 2014 [Page 7] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 including "point-to-point" (P2P), "multipoint-to-point" (MP2P), and "point-to-multipoint" (P2MP) flows as: o P2P: Point To Point. This 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 time between two communication end-points. 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 802.15.4 link layers) to many Gigabytes per second (e.g., on fiber optics). For management purposes, the management protocol typically requires to send 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, and thus management is not possible with such a protocol. Networks without bandwidth limitation (e.g. Ethernet) are in-scope of this document if they are used with constrained devices (see the use case "Building Automation" in [COM-US]). 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 10Gbit Ethernet. For wireless networks, such as 802.15.4, Ersue, et al. Expires April 28, 2014 [Page 8] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 the bit error rate can be as high as 10^-1 to 10^-0 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. Note: The discussion on the management requirements of MANETs is currently not in the focus of this document. [COM-US] provides a use case to make it clear how a MANET-based application differs from others. 1.4. Constrained Device Deployment Options We differentiate following Deployment options for the constrained devices: o a network of constrained devices, which communicate with each other, o Constrained devices, which are connected directly to the Internet or an IP network o A network of constrained devices which communicate with a gateway or proxy with more communication capabilities acting possibly as a representative of the device to entities in the non-constrained network o Constrained devices, which 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 system 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 1.5. Management Topology Options We differentiate 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/ Ersue, et al. Expires April 28, 2014 [Page 9] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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 constrained network 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 constrained networks are managed by the managers at their corresponding hierarchy level. I.e. each manager is responsible for managing the nodes in its sub-network. It passes information from its sub-network to its higher-level manager, and disseminates management functions received from the higher-level manager to its sub-network. 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 network or devices. A constrained device: o might only support an unreliable radio with lossy links, i.e. the client and server of a management protocol need to gracefully ignore incomplete commands or repeat commands as necessary. 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), 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 Ersue, et al. Expires April 28, 2014 [Page 10] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 modular implementation and a very basic version with just a few simple commands. 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, which support data compression (e.g. C2) and devices, which do not support data compression (e.g. C1 and C0). o might only be able to support very simple encryption, i.e. it would be efficient if the devices use cryptographic algorithms that are supported in hardware. o might only be able to communicate with one single managing entity and cannot support the parallel access of many managing entities. 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 feature, 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. Ersue, et al. Expires April 28, 2014 [Page 11] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 o might only be able to support a soft-reset from failure recovery. o might possibly generate a huge amount of redundant reporting data, i.e. the intermediary management entity (see [I-D.ietf-core-coap]) should be able to filter and aggregate redundant data. A constrained network: o might only support an unreliable radio with lossy links, 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. o must be able to self-organize, i.e. given the large number of nodes and their potential placement in hostile locations and frequently changing topology, manual configuration is typically not feasible. As such the network must be able to reconfigure itself so that it can continue to operate properly and support reliable connectivity. o needs a management solution, which 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, which 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 enabling. In such a case it should be possible to run the protocol possibly at a reduced level but avoiding to fail completely. E.g. self- monitoring mechanisms or graceful degradation of features can be used to provide fault tolerance. Ersue, et al. Expires April 28, 2014 [Page 12] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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 algorithms for security. Ersue, et al. Expires April 28, 2014 [Page 13] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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 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 a limited memory and CPU power as well as aim to be self-configuring and easy to deploy. However, the tininess of the network nodes requires a rethinking of the protocol characteristics concerning power consumption, performance, memory, and CPU usage. As such, there is a demand for protocol simplification, energy-efficient communication, less CPU usage and small memory footprint. On the application layer the IETF is already developing protocols like the Constrained Application Protocol (CoAP) [I-D.ietf-core-coap] supporting constrained devices and networks e.g., for smart energy applications or home automation environments. The deployment of such an environment involves in fact many, in some scenarios up to million small devices (e.g. smart meters), which produce a huge amount of data. This data needs to be collected, filtered, and pre-processed for further use in diverse services. Considering the high number of nodes to deploy, one has to think on 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 is already a reality in the standards of some of the bodies such as 3GPP. To introduce self-configuration of smart devices successfully a device-initiated connection establishment is required. A simple 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, Ersue, et al. Expires April 28, 2014 [Page 14] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 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 to be too heavyweight compared to the capabilities the constrained devices have and are not applicable directly for the use in a network of constrained devices. Furthermore, the data models addressing the requirements of such smart devices need yet to be designed. 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 and CPU resources, use today, 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, as well as reduced requirements coming from smart devices and the network of such constrained devices. Albeit it is questionable whether we can take the same comprehensive approach we use in an IP network also for the management of constrained devices. Hence, the management of a network with constrained devices is necessary to design in a simplified and less complex manner. As the Section 1.6 highlights, there are diverse characterists of constrained devices or networks, which stem from their constraindness and therefor have an impact on the requirements for the management of such a network with constrained devices. The use cases discussed in [COM-US] 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 which are new in the context of constrained devices. Examples of such issues are e.g. the careful management of the 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, which need to be addressed for the management of a network with constrained devices please see Section 1.6 and Section 3. Ersue, et al. Expires April 28, 2014 [Page 15] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 3. Requirements on the Management of Networks with Constrained Devices This section describes the requirements categorized by management areas listed in subsections. Note that the requirements in this section need to be seen as standalone requirements. A device might be able to provide only a particular profile of requirements (i.e. selected set of requirements) and might not be capable to provide all requirements in this document. On the other hand a device vendor might select a subset of the requirements to implement. As of today this document does not recommend the realization of a profile of requirements. Following template is used for the definition of the requirements. Req-ID: An ID uniquely identified by a three-digit number Title: The title of the requirement. Description: The rational and description of the requirement. Source: The origin of the requirement and the matching use case or application. For the discussion of referred use cases for constrained management please see [COM-US]. Requirement Type: Functional Requirement, Non-Functional Requirement. A functional requirement is related to a proposed function or component. As such functional requirements may be technical details, or specific functionality that define what a system is supposed to accomplish. Non-functional requirements (also known as design constraints or quality requirements) impose implementation related considerations such as performance requirements, security, or reliability. Device type: The device types by which this requirement can be supported: C0, C1 and/or C2. Priority: The priority of the requirement showing it's importance for a particular type of device: High, Medium, and Low. The priority of a requirement can be High e.g. for a C2 device but Low for a C1 or C0 device as the realization of complex features in a C1 device is in many cases not possible. 3.1. Management Architecture/System Ersue, et al. Expires April 28, 2014 [Page 16] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Req-ID: 4.1.001 Title: Support multiple device classes within a single network. Description: Larger networks usually are made up of devices belonging to different device classes (e.g., constrained mesh endpoints and less constrained routers) that work together. Hence, the management architecture must be applicable to networks that have a mix of different device classes. See Section 3. of [I-D.ietf-lwig-terminology] for the definition of Constrained Device Classes. Source: All use cases. Requirement Type: Non-Functional Requirement Device type: Managing and intermediary entities. Priority: High --- Req-ID: 4.1.002 Title: Management scalability. Description: The management architecture must be able to scale with the number of devices involved and operate efficiently in any network size and topology. This implies that e.g. the managing entity is able to handle huge amount of device monitoring data and the management protocol is not sensitive to the decrease of the time between two client requests. To achieve good scalability, caching techniques, in-network data aggregation techniques, hierarchical management models may be used. Source: General requirement for all use cases to enable large scale networks. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High --- Ersue, et al. Expires April 28, 2014 [Page 17] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Req-ID: 4.1.003 Title: Hierarchical management Description: Provide a means of hierarchical management, i.e. provide intermediary management entities on different levels, which can take over the responsibility for the management of a sub-hierarchy of the network of constraint devices. The intermediary management entity can e.g. support management data aggregation to handle e.g. high-frequent monitoring data or provide a caching mechanism for the uplink and downlink communication. Hierarchical management contributes to management scalability. Source: Use cases where a huge amount of devices are deployed with a hierarchical topology. Requirement Type: Non-Functional Requirement Device type: Managing and intermediary entities. Priority: Medium --- Req-ID: 4.1.004 Title: Minimize state maintained on constrained devices. Description: The amount of state that needs to be maintained on constrained devices should be minimized. This is important in order to save memory (especially relevant for C0 and C1 devices) and in order to allow devices to restart for example to apply configuration changes or to recover from extended periods of inactivity. One way to achieve this is to adopt a RESTful architecture that minimizes the amount of state maintained by managed constrained devices and that makes resources of a device addressable via URIs. Source: Basic requirement which concerns all use cases. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Ersue, et al. Expires April 28, 2014 [Page 18] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Priority: High --- Req-ID: 4.1.005 Title: Automatic re-synchronization with eventual consistency. Description: To support large scale networks, where some constrained devices may be offline at any point in time, it is necessary to distribute configuration parameters in a way that allows temporary inconsistencies but eventually converges, after a sufficiently long period of time without further changes, towards global consistency. Source: Use cases with large scale networks with many devices. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.1.006 Title: Support for lossy links and unreachable devices. Description: Some constrained devices will only be able to support lossy and unreliable links characterized by a limited data rate, a high latency, and a high transmission error rate. Furthermore constrained devices often duty cycle their radio or the whole device in order to save energy. In both cases the management system must not assume that constrained devices are always reachable. The management protocol(s) must act gracefully if a conctrained device is not reachable and provide a high degree of resilience. Intermediaries may be used that provide information for devices currently inactive or that take responsibility to re- synchronize devices when they become reachable again after an extended offline period. Source: Basic requirement for constrained networks with unreliable links and constrained devices which sleep to save energy. Ersue, et al. Expires April 28, 2014 [Page 19] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.1.007 Title: Network-wide configuration Description: Provide means by which the behavior of the network can be specified at a level of abstraction (network-wide configuration) higher than a set of configuration information specific to individual devices. It is useful to derive the device specific configuration from the network-wide configuration. The identification of the relevant subset of the policies to be provisioned is according to the capabilities of each device and can be obtained from a pre-configured data-repository. Such a repository can be used to configure pre-defined device or protocol parameters for the whole network. Furthermore, such a network- wide view can be used to monitor and manage a group of routers or a whole network. E.g. monitoring the performance of a network requires additional information other than what can be acquired from a single router using a management protocol. Source: In general all use cases, which want to configure the network and its devices based on a network view in a top-down manner. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: Medium --- Req-ID: 4.1.008 Title: Distributed Management Description: Provide a means of simple distributed management, where a constrained network can be managed or monitored by more than one manager. Since the connectivity to a server cannot be guaranteed at all times, a distributed approach may provide a higher reliability, at the cost of increased complexity. This Ersue, et al. Expires April 28, 2014 [Page 20] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 requirement implies the handling of data consistency in case of concurrent read and write access to the device datastore. It might also happen that no management (configuration) server is accessible and the only reachable node is a peer device. In this case the device should be able to obtain its configuration from peer devices. Source: Use cases where the count of devices to manage is high. Requirement Type: Non-Functional Requirement Device type: C1 and C2 Priority: Medium 3.2. Management protocols and data model Req-ID: 4.2.001 Title: Modular implementation of management protocols Description: Management protocols should allow modular implementations, i.e., it should be possible to implement only a basic set of protocol primitives on highly constrained devices while devices with additional resources may provide more support for additional protocol primitives. It should be possible to discover the management protocol primitives by a device. Source: Basic requirement interesting for all use cases. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.2.002 Title: Compact encoding of management data Description: The encoding of management data should be compact and space efficient, enabling small message sizes. Ersue, et al. Expires April 28, 2014 [Page 21] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: General requirement to save memory for the receiver buffer and on-air bandwith. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.2.003 Title: Compression of management data or complete messages Description: Management data exchanges can be further optimized by applying data compression techniques or delta encoding techniques. Compression typically requires additional code size and some additional buffers and/or the maintenance of some additional state information. For C0 devices compression may not be feasible. As such, this requirement is marked as optional. Source: Use cases where it is beneficial to reduce transmission time and bandwith, e.g. mobile applications which require to save on- air bandwith. Requirement Type: Functional Requirement Device type: C1 and C2 Priority: Medium --- Req-ID: 4.2.004 Title: Mapping of management protocol interactions. Description: It is desirable to have a loss-less automated mapping between the management protocol used to manage constrained devices and the management protocols used to manage regular devices. In the ideal case, the same core management protocol can be used with certain restrictions taking into account the resource limitations of constrained devices. However, for very resource constrained devices, this goal might not be achievable. Hence this requirement is marked optional for device class C2. Ersue, et al. Expires April 28, 2014 [Page 22] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: Use cases where high-frequent interaction with the management system of a non-constrained network is required. Requirement Type: Functional Requirement Device type: C2 Priority: Medium --- Req-ID: 4.2.005 Title: Consistency of data models with the underlying information model. Description: The data models used by the management protocol must be consistent with the information model used to define data models for non-constrained networks. This is essential to facilitate the integration of the management of constrained networks with the management of non-constrained networks. Using an underlying information model for future data model design enables furthermore top-down model design and model reuse as well as data interoperability (i.e. exchange of management information between the constrained and non-constrained networks). This is a strong requirement, even despite the fact that the underlying information models are often not explicitly documented in the IETF. Source: General requirement to support data interoperability, consistency and model reuse. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.2.006 Title: Loss-less mapping of management data models. Description: It is desirable to have a loss-less automated mapping between the management data models used to manage regular devices and the management data models used for managing constrained devices. In the ideal case, the same core data models can be used with certain restrictions taking into account the resource Ersue, et al. Expires April 28, 2014 [Page 23] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 limitations of constrained devices. However, for very resource constrained devices, this goal might not be achievable. Hence this requirement is marked optional for device class C2. Source: Use cases where consistent data exchange with the management system of a non-constrained network is required. Requirement Type: Functional Requirement Device type: C2 Priority: Medium --- Req-ID: 4.2.007 Title: Protocol extensibility Description: Provide means of extensibility for the management protocol, i.e. by adding new protocol messages or mechanisms that can deal with the changing requirements on a supported message and data types effectively, without causing inter-operability problems or having to replace/update large amounts of deployed devices. Source: Basic requirement useful for all use cases. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High 3.3. Configuration management Req-ID: 4.3.001 Title: Self-configuration capability Description: Automatic configuration and re-configuration of devices without manual intervention. Compared to the traditional management of devices where the management application is the central entity configuring the devices, in the auto-configuration scenario the device is the active part and initiates the configuration process. Self-configuration can be initiated during the initial configuration or for subsequent configurations, where the configuration data needs to be refreshed. Self-configuration should be also supported during the initialization phase or in the Ersue, et al. Expires April 28, 2014 [Page 24] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 event of failures, where prior knowledge of the network topology is not available or the topology of the network is uncertain. Source: In general all use cases requiring easy deployment and plug& play behavior as well as easy maintenance of many constrained devices. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High for device categories C0 and C1, Medium for C2. --- Req-ID: 4.3.002 Title: Capability Discovery Description: Enable the discovery of supported optional management capabilities of a device and their exposure via at least one protocol and/or data model. Source: Use cases where the device interaction with other devices or applications is a function of the level of support for its capabilities. Requirement Type: Functional Requirement Device type: C1 and C2 Priority: Medium --- Req-ID: 4.3.003 Title: Asynchronous Transaction Support Description: Provide configuration management with asynchronous transaction support. Configuration operations must support a transactional model, with asynchronous indications that the transaction was completed. Source: Use cases, which require transaction-oriented processing because of reliability or distributed architecture functional requirements. Ersue, et al. Expires April 28, 2014 [Page 25] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Requirement Type: Functional Requirement Device type: C1 and C2 Priority: Medium --- Req-ID: 4.3.004 Title: Network reconfiguration Description: Provide a means of iterative network reconfiguration in order to recover the network functionality from node and communication faults. The network reconfiguration can be failure- driven and self-initiated (automatic reconfiguration). The network reconfiguration can be also performed on the whole hierarchical structure of a network (network topology). Source: Practically all use cases, as network connectivity is a basic requirement. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium 3.4. Monitoring functionality Req-ID: 4.4.001 Title: Device status monitoring Description: Provide a monitoring function to collect and expose information about device status and exposing it via at least one management interface. The device monitoring might make use of the hierarchical management through the intermediary entities and the data caching mechanism. The device monitoring might also make use of neighbor-monitoring (fault detection in local network) to support fast fault detection and recovery, e.g. in a scenario where a managing entity is unreachable and a neighbor can take over the monitoring responsibility. Source: All use cases Ersue, et al. Expires April 28, 2014 [Page 26] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High, Medium for neighbor-monitoring. --- Req-ID: 4.4.002 Title: Energy status monitoring Description: Provide a monitoring function to collect and expose information about device energy parameters and usage (e.g. battery level and communication power). Source: Use case Energy Management Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High for energy reporting devices, Low for others. --- Req-ID: 4.4.003 Title: Monitoring of current and estimated device availability Description: Provide a monitoring function to collect and expose information about current device availability (energy, memory, computing power, forwarding plane utilization, queue buffers, etc.) and estimation of remaining available resources. Source: All use cases. Note that monitoring energy resources (like battery status) may be required on all kinds of devices. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium --- Ersue, et al. Expires April 28, 2014 [Page 27] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Req-ID: 4.4.004 Title: Network status monitoring Description: Provide a monitoring function to collect and expose information related to the status of a network or network segments connected to the interfaces of the device. Source: All use cases. Requirement Type: Functional Requirement Device type: C1 and C2 Priority: Low, based on the realization complexity. --- Req-ID: 4.4.005 Title: Self-monitoring Description: Provide self-monitoring (local fault detection) feature for fast fault detection and recovery. Source: Use cases where the devices cannot be monitored centrally in appropriate manner, e.g. self-healing is required. Requirement Type: Functional Requirement Device type: C1 and C2 Priority: High for C2, Medium for C1 --- Req-ID: 4.4.006 Title: Performance Monitoring Description: The device will provide a monitoring function to collect and expose information about the basic performance parameter (TBD) of the device. The performance management functionality might make use of the hierarchical management through the intermediary devices. Ersue, et al. Expires April 28, 2014 [Page 28] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: Use cases Building automation, and Transport applications Requirement Type: Functional Requirement Device type: C1 and C2 Priority: Low --- Req-ID: 4.4.007 Title: Fault detection monitoring Description: The device will provide fault detection monitoring. The system collects information about network states in order to identify whether faults have occurred. In some cases the detection of the faults might be based on the processing and analysis of the parameters retrieved from the network or other devices. In case of C0 devices the monitoring might be limited to the check whether the device is alive or not. Source: Use cases Environmental Monitoring, Building Automation, Energy Management, Infrastructure Monitoring Requirement Type: Functional Requirement Device type: C0, C1 and C2 Priority: Medium --- Req-ID: 4.4.008 Title: Passive and Reactive Monitoring Description: The device will provide passive and reactive monitoring capabilities. The system or manager collects information about device components and network states (passive monitoring) and may perform postmortem analysis of collected data. In case events of interest have occurred the system or manager can adaptively react (reactive monitoring), e.g. reconfigure the network. Typically actions (re-actions) will be executed or sent as commands by the management applications. Ersue, et al. Expires April 28, 2014 [Page 29] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: Diverse use cases relevant for device status and network state monitoring Requirement Type: Functional Requirement Device type: C2 Priority: Medium --- Req-ID: 4.4.009 Title: Recovery Description: Provide local, central and hierarchical recovery mechanisms (recovery is in some cases achieved by recovering the whole network of constrained devices). Source: Use cases Industrial applications, Home and Building Automation, Mobile Applications that involve different forms of clustering or area managers. Requirement Type: Functional Requirement Device type: C2 Priority: Medium --- Req-ID: 4.4.010 Title: Network topology discovery Description: Provide a network topology discovery capability (e.g. use of topology extraction algorithms to retrieve the network state) and a monitoring function to collect and expose information about the network topology. Source: Use cases Community Network Applications and Mobile Applications Requirement Type: Functional Requirement Ersue, et al. Expires April 28, 2014 [Page 30] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Device type: C1 and C2 Priority: Low, based on the realization complexity. --- Req-ID: 4.4.011 Title: Notifications Description: The device will provide the capability of sending notifications on critical events and faults. Source: All use cases. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium for C2, Low for C1 --- Req-ID: 4.4.012 Title: Logging Description: The device will provide the capability of building, keeping, and allowing retrieval of logs of events (including but not limited to critical faults and alarms). Source: Use cases Industrial Applications, Building Automation, Infrastructure monitoring Requirement Type: Functional Requirement Device type: C2 Priority: High for some medical or industrial applications, Medium otherwise 3.5. Self-management Req-ID: 4.5.001 Ersue, et al. Expires April 28, 2014 [Page 31] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Title: Self-management - Self-healing Description: Enable event-driven and/or periodic self-management functionality in a device. The device should be able to react in case of a failure e.g. by initiating a fully or partly reset and initiate a self-configuration or management data update as necessary. A device might be further able to check for failures cyclically or schedule-controlled to trigger self-management as necessary. It is a matter of device design and subject for discussion how much self-management a C1 device can support. A minimal failure detection and self-management logic is assumed to be generally useful for the self-healing of a device. Source: The requirement generally relates to all use cases in this document. Requirement Type: Functional Requirement Device type: C1 and C2 Priority: High for C2, Medium for C1 3.6. Security and Access Control Req-ID: 4.6.001 Title: Authentication of management system and devices. Description: Systems having a management role must be properly authenticated to the device such that the device can exercise proper access control and in particular distinguish rightful management systems from rogue systems. On the other hand managed devices must authenticate themselves to systems having a management role such that management systems can protect themselves from rogue devices. In certain application scenarios, it is possible that a large number of devices need to be (re)started at about the same time. Protocols and authentication systems should be designed such that a large number of devices (re)starting simultaneously does not negatively impact the device authentication process. Source: Basic security requirement for all use cases. Requirement Type: Functional Requirement Ersue, et al. Expires April 28, 2014 [Page 32] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Device type: C0, C1, and C2 Priority: High, Medium for the (re)start of a large number of devices --- Req-ID: 4.6.002 Title: Support suitable security bootstrapping mechanisms Description: Mechanisms should be supported that simplify the bootstrapping of device that is the discovery of newly deployed devices in order to add them to access control lists. Source: Basic security requirement for all use cases. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: High --- Req-ID: 4.6.003 Title: Access control on management system and devices Description: Systems acting in a management role must provide an access control mechanism that allows the security administrator to restrict which devices can access the managing system (e.g., using an access control white list of known devices). On the other hand managed constrained devices must provide an access control mechanism that allows the security administrator to restrict how systems in a management role can access the device (e.g., no- access, read-only access, and read-write access). Source: Basic security requirement for use cases where access control is essential. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Ersue, et al. Expires April 28, 2014 [Page 33] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Priority: High --- Req-ID: 4.6.004 Title: Select cryptographic algorithms that are efficient in both code space and execution time. Description: Cryptographic algorithms have a major impact in terms of both code size and overall execution time. It is therefore necessary to select mandatory to implement cryptographic algorithms (like some elliptic curve algorithm) that are reasonable to implement with the available code space and that have a small impact at runtime. Furthermore some wireless technologies (e.g., IEEE 802.15.4) require the support of certain cryptographic algorithms. It might be useful to choose algorithms that are likely to be supported in wireless chipsets for certain wireless technologies. Source: Generic requirement to reduce the footprint and CPU usage of a constrained device. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High, Medium for hardware-supported algorithms. 3.7. Energy Management Req-ID: 4.7.001 Title: Management of Energy Resources Description: Enable managing power resources in the network, e.g. reduce the sampling rate of nodes with critical battery and reduce node transmission power, put nodes to sleep, put single interfaces to sleep, reject a management job based on available energy, criteria e.g. importance levels pre-defined by the management application, etc. (e.g. a task marked as essential can be executed even if the energy level is low). The device may further implement standard data models for energy management and expose it through a management protocol interface, e.g. EMAN MIB modules and extensions. It might be necessary to downscale EMAN MIBs for the use in C1 and C2 devices. Ersue, et al. Expires April 28, 2014 [Page 34] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: Use case Energy Management Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium for the use case Energy Management, Low otherwise. --- Req-ID: 4.7.002 Title: Support of energy-optimized communication protocols Description: Use of an optimized communication protocol to minimize energy usage for the device (radio) receiver/transmitter, on-air bandwidth (protocol efficiency), reduced amount of data communication between nodes (implies data aggregation and filtering but also a compact format for the transferred data). Source: Use cases Energy Management and Mobile Applications. Requirement Type: Non-Functional Requirement Device type: C2 Priority: Medium --- Req-ID: 4.7.003 Title: Support for layer 2 energy-aware protocols Description: The device will support layer 2 energy management protocols (e.g. energy-efficient Ethernet IEEE 802.3az) and be able to report on these. Source: Use case Energy Management Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: Medium --- Ersue, et al. Expires April 28, 2014 [Page 35] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Req-ID: 4.7.004 Title: Dying gasp Description: When energy resources draw below the red line level, the device will send a dying gasp notification and perform if still possible a graceful shutdown including conservation of critical device configuration and status information. Source: Use case Energy Management Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium 3.8. SW Distribution Req-ID: 4.8.001 Title: Group-based provisioning Description: Support group-based provisioning, i.e. firmware update and configuration management, of a large set of constrained devices with eventual consistency and coordinated reload times. The device should accept group-based configuration management based on bulk commands, which aim similar configurations of a large set of constrained devices of the same type in a given group. Activation of configuration may be based on pre-loaded sets of default values. Source: All use cases Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: Medium 3.9. Traffic management Req-ID: 4.9.001 Title: Congestion avoidance Ersue, et al. Expires April 28, 2014 [Page 36] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Description: Provide the ability to avoid congestion by modifying the device's reporting rate for periodical data (which is usually redundant) based on the importance and reliability level of the management data. This functionality is usually controlled by the managing entity, where the managing entity marks the data as important or relevant for reliability. However reducing a device's reporting rate can also be initiated by a device if it is able to detect congestion or has insufficient buffer memory. Source: Use cases with high reporting rate and traffic e.g. AMI or M2M. Requirement Type: Non-Functional Requirement Device type: C1 and C2 Priority: Medium --- Req-ID: 4.9.002 Title: Redirect traffic Description: Provide the ability for network nodes to redirect traffic from overloaded intermediary nodes in a network to another path in order to prevent congestion on a central server and in the primary network. Source: Use cases with high reporting rate and traffic e.g. AMI or M2M. Requirement Type: Non-Functional Requirement Device type: Intermediary entity in the network. Priority: Medium --- Req-ID: 4.9.003 Title: Traffic delay schemes. Description: Provide the ability to apply delay schemes to incoming and outgoing links on an overloaded intermediary node as necessary in order to reduce the amount of traffic in the network. Ersue, et al. Expires April 28, 2014 [Page 37] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Source: Use cases with high reporting rate and traffic e.g. AMI or M2M. Requirement Type: Non-Functional Requirement Device type: Intermediary entity in the network. Priority: Medium 3.10. Transport Layer Req-ID: 4.10.001 Title: Scalable transport layer Description: Enable the use of a scalable transport layer, i.e. not sensitive to the decrease of the time between two client requests, which is useful for applications requiring frequent access to device data. Source: Applications with high frequent access to the device data. Requirement Type: Non-Functional Requirement Device type: C0, C1 and C2 Priority: Medium --- Req-ID: 4.10.002 Title: Reliable unicast transport of messages Description: Diverse applications need a reliable transport of messages. The reliability might be achieved based on a transport protocol such as TCP or can be supported based message repetition if an acknowledgement is missing. Source: Generally applications benefit from the reliability of the message transport. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Ersue, et al. Expires April 28, 2014 [Page 38] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Priority: High --- Req-ID: 4.10.003 Title: Best-effort multicast Description: Provide best-effort multicast of messages, which is generally useful when devices need to discover a service provided by a server or many devices need to be configured by a managing entity at once based on the same data model. Source: Use cases where a device needs to discover services as well as use cases with high amount of devices to manage, which are hierarchically deployed, e.g. AMI or M2M. Requirement Type: Functional Requirement Device type: C0, C1, and C2 Priority: Medium Req-ID: 4.10.004 Title: Secure message transport. Description: Enable secure message transport providing authentication, data integrity, confidentiality by using existing transport layer technologies with small footprint such as TLS/ DTLS. Source: All use cases. Requirement Type: Non-Functional Requirements Device type: C1 and C2 Priority: High 3.11. Implementation Requirements Req-ID: 4.11.001 Title: Avoid complex application layer transactions requiring large application layer messages. Ersue, et al. Expires April 28, 2014 [Page 39] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Description: Complex application layer transactions tend to require large memory buffers that are typically not available on C0 or C1 devices and only by limiting functionality on C2 devices. Furthermore, the failure of a single large transaction requires repeating the whole transaction. On constrained devices, it is often more desirable to a large transaction down into a sequence of smaller transactions, which require less resources and allow to make progress using a sequence of smaller steps. Source: Basic requirement which concerns all use cases with memory constrained devices. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High Req-ID: 4.11.002 Title: Avoid reassembly of messages at multiple layers in the protocol stack. Description: Reassembly of messages at multiple layers in the protocol stack requires buffers at multiple layers, which leads to inefficient use of memory resources. This can be avoided by making sure the application layer, the security layer, the transport layer, the IPv6 layer and any adaptation layers are aware of the limitations of each other such that unnecessary fragmentation and reassembly can be avoided. In addition, message size constraints must be announced to protocol peers such that they can adapt and avoid sending messages that can't be processed due to resource constraints on the receiving device. Source: Basic requirement which concerns all use cases with memory constrained devices. Requirement Type: Non-Functional Requirement Device type: C0, C1, and C2 Priority: High Ersue, et al. Expires April 28, 2014 [Page 40] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 4. IANA Considerations This document does not introduce any new code-points or namespaces for registration with IANA. Note to RFC Editor: this section may be removed on publication as an RFC. Ersue, et al. Expires April 28, 2014 [Page 41] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 5. Security Considerations This document discusses the problem statement and requirements on the network of constrained devices. If specific requirements for security will be identified, they will be described in future versions of this document. Ersue, et al. Expires April 28, 2014 [Page 42] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 6. Contributors Ulrich Herberg (Fujitsu Laboratories of America) contributed to the Section 1.3 on Networks Types and Characteristics in Focus. Ersue, et al. Expires April 28, 2014 [Page 43] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 7. Acknowledgments Following persons reviewed and provided valuable comments to different versions of this document: Dominique Barthel, Carsten Bormann, Zhen Cao, Benoit Claise, Bert Greevenbosch, Ulrich Herberg, James Nguyen, Anuj Sehgal, Zach Shelby, and Peter van der Stok. The editors would like to thank the reviewers and the participants on the Coman maillist for their valuable contributions and comments. Ersue, et al. Expires April 28, 2014 [Page 44] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 8. References 8.1. Normative References 8.2. Informative References [RFC6632] Ersue, M. and B. Claise, "An Overview of the IETF Network Management Standards", RFC 6632, June 2012. [I-D.ietf-lwig-terminology] Bormann, C., Ersue, M., and A. Keranen, "Terminology for Constrained Node Networks", draft-ietf-lwig-terminology-05 (work in progress), July 2013. [I-D.ietf-core-coap] Shelby, Z., Hartke, K., and C. Bormann, "Constrained Application Protocol (CoAP)", draft-ietf-core-coap-18 (work in progress), June 2013. [I-D.ietf-roll-terminology] Vasseur, J., "Terms used in Ruting for Low power And Lossy Networks", draft-ietf-roll-terminology-13 (work in progress), October 2013. [M2MDEVCLASS] Open Mobile Alliance, "OMA M2M Device Classification v1.0", October 2012, . [EU-IOT-A] EU Commission Seventh Framework Programme, "EU FP7 Project Internet-of-Things Architecture", . [EU-SENSEI] EU Commission Seventh Framework Programme, "EU Project SENSEI", . [EU-FI-WARE] EU Commission Future Internet Public Private Partnership (FI-PPP), "EU Project Future Internet-Core Platform", . [EU-IOT-BUTLER] EU Commission Seventh Framework Programme, "EU FP7 Project Butler Smartlife", . [COM-US] Ersue, M., "Constrained Management: Use Cases", Ersue, et al. Expires April 28, 2014 [Page 45] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 draft-ersue-coman-use-cases (work in progress), October 2013. Ersue, et al. Expires April 28, 2014 [Page 46] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Appendix A. Related Development in other Bodies Note that over time the summary on the related work in other bodies might become outdated. A.1. ETSI TC M2M ETSI Technical Committee Machine-to-Machine (ETSI TC M2M) aims to provide an end-to-end view of M2M standardization, which enables the integration of multiple vertical M2M applications. The main goal is to overcome the current M2M market fragmentation and to reuse existing mechanisms from telecom standards such as from OMA or 3GPP. ETSI Release 1 is functionally frozen. The main focus is on use cases for Smart Metering (Technical Report (TR) 102 691) but it also includes eHealth use cases (TR 102 732) and some others. The Service requirements (Technical Standard (TS) 102 689) derived from the use cases, and the functional architecture specification (TS 102 690), will together define the M2M platform. The architecture consists of Service Capabilities (SC), which are basic functional building blocks for building the M2M platform. Smart Metering is seen as the important showcase for M2M. It is believed that the Service Enablers that were defined based on the work done for Smart Metering and eHealth segments will also allow the building of other services like vending machines, alarm systems etc. The functional architecture includes following management-related definitions: o Network Management Functions: consists of all functions required to manage the Access, Transport and Core networks: these include Provisioning, Supervision, Fault Management, etc. o M2M Management Functions: consists of functions required to manage generic functionalities of M2M Applications and M2M Service Capabilities in the Network and Applications Domain. The management of the M2M Devices and Gateways may use specific M2M Service Capabilities. The Release 2 work of ETSI TC M2M has started beginning of 2012. Following is a list of networking- and management-related topics under work: o Interworking with 3GPP networks. This is a new work item, and no discussion has been held on technical details. The intent is to define which ETSI TC M2M functions are applicable when 3GPP NW is used as transport. It is possible that this work would also cover Ersue, et al. Expires April 28, 2014 [Page 47] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 details on how to use 3GPP interfaces, e.g. those defined in the SIMTC work, but also for charging and policy control. o Creating a Semantic Model or Data Abstraction layer for vertical industries and interworking. This would provide some high level information description that would be usable for interworking with local networks (e.g. ZigBee), and also for verticals, and it would allow the ETSI Service Enablement layer to also understand the data, instead of being just a bit storage and bit pipe. All technical details are still under discussion, but it has been agreed that a function for this exists in the architecture at least for interworking. A.2. OASIS Developments in OASIS related to management of constrained networks are following: o The Energy Interoperation TC works to define interaction between Smart Grids and their end nodes, including Smart Buildings, Enterprises, Industry, Homes, and Vehicles. The TC develops data and communication models that enable the interoperable and standard exchange of signals for dynamic pricing, reliability, and emergencies. The TC's agenda also extends to the communication of market participation data (such as bids), load predictability, and generation information. The first version of the Energy Interoperation specification is in final review. o OASIS Open Data Protocol (OData) aims to simplify the querying and sharing of data across disparate applications and multiple stakeholders for re-use in the enterprise, Cloud, and mobile devices. As a REST-based protocol, OData builds on HTTP, AtomPub, and JSON using URIs to address and access data feed resources. It enables information to be accessed from a variety of sources including (but not limited to) relational databases, file systems, content management systems, and traditional Web sites. o Open Building Information Exchange (oBIX) aims to enable the mechanical and electrical control systems in buildings to communicate with enterprise applications, and to provide a platform for developing new classes of applications that integrate control systems with other enterprise functions. Enterprise functions include processes such as Human Resources, Finance, Customer Relationship Management (CRM), and Manufacturing. Ersue, et al. Expires April 28, 2014 [Page 48] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 A.3. OMA OMA is currently working on Lightweight M2M Enabler, OMA Device Management (OMA DM) Next Generation, and a white paper on M2M Device Classification. The Lightweight M2M Enabler covers both M2M device management and service management for constrained devices. In the case of less constrained devices, OMA DM Next Generation Enabler may be more appropriate. OMA DM is structured around Management Objects (MO), each specified for a specific purpose. There is also ongoing work with various other MOs such as the Gateway Management Object (GwMO). A draft for the "Lightweight M2M Requirements" is available. OMA Lightweight M2M and OMA DM Next Generation are important to M2M device management, provisioning and service managements in both the protocol and management objects. OMA Lightweight M2M work seems to have grown from its original scope of being targeted for very simple devices only, i.e. such that could not handle all those protocols that ETSI M2M requires. The white paper on the M2M Device Classification [M2MDEVCLASS] provides an M2M device classification framework based on the horizontal attributes (e.g., wide or local area communication interface, IP stack, I/O capabilities) of interest to communication service providers and M2M service providers, independent of vertical markets, such as smart grid, connected cars, e-health, etc. The white paper can be used as a tool to analyze the applicability of existing requirements and specifications developed by OMA and other cooperative standards development organizations. A.4. IPSO Alliance IPSO Alliance developed a profile for Device Functions supporting devices such as sensors with a limited user interface, where the configuration of even basic parameters is impossible to do manually. This is a challenge especially for consumer devices that are managed by non-professional users. The configuration of a web service application running on a constrained device goes beyond the autoconfiguration of the IP stack and local information (e.g. proxy address). Constrained devices need additionally service provider and user account related configuration, such as an address/locator and the username for a web server. IPSO discusses the use cases and requirements for user friendly configuration of such information on a constrained device, and specifies how IPSO profile Device Function Set can be used in the process. It furthermore defines a standard format for the basic Ersue, et al. Expires April 28, 2014 [Page 49] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 application configuration information. Ersue, et al. Expires April 28, 2014 [Page 50] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Appendix B. Related Research Projects o The EU project IoT-A (Internet-of-Things Architecture) develops an architectural reference model together with the definition of an initial set of key building blocks. These enable the integration of IoT into the service layer of the Future Internet, and realize a novel resolution infrastructure, as well as a network infrastructure that allows the seamless communication flow between IoT devices and services. The development includes a conceptual model of a smart object as well as a basic Internet of Things reference model defining the interaction and communication between IoT devices and relevant entities. The requirements document includes also network and information management requirements (see [EU-IOT-A]). o The EU project SENSEI specified the document on 'End to End Networking and Management' for Wireless Sensor and Actuator Networks. This report presents several research results carried out in SENSEI's tasks related to End-to-End Networking and Management. Particular analyses have been addressed related to naming and addressing of resources, management of resources, resource plug and play, resource level mobility and traffic modelling. The detailed analysis on each of these topics is intended to identify possible gaps between their specific mechanisms and the functional requirements in the SENSEI reference architecture (see [EU-SENSEI]). o The EU project FI-WARE is developing the Things Management GE (generic enabler), which uses a data model derived from the OMA DM NGSI data model. Using the abstraction level of things which include non-technical things like rooms, places and people, Things Management GE aims to discover and look up IoT resources that can provide information about things or actuate on these things. The system aimes to manage the dynamic associations between IoT resources and things in order to allow internal components as well as external applications to interact with the system using the thing abstraction as the core concept (see [EU-FI-WARE]). o EU project BUTLER Smart Life discusses different IoT management aspects and collects requirements for smart life use cases (e.g. smart home or smart city) mainly from service management pov. (see [EU-IOT-BUTLER]). Ersue, et al. Expires April 28, 2014 [Page 51] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Appendix C. Open issues o Section 4 on the management requirements, as the core section in the document, needs further consolidation. Ersue, et al. Expires April 28, 2014 [Page 52] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Appendix D. Change Log D.1. draft-ersue-constrained-mgmt-03 - draft-ersue-opsawg-coman-probstate-reqs-00 o Reduced the terminology section for terminology addressed in the LWIG terminology draft. Referenced the LWIG terminology draft. o Checked and aligned all terminology against the LWIG terminology draft. o Moved section 1.4. Constrained Device Deployment Options and section 3. Use Cases to the companion document [COM-US]. o Renamed Section 1.3. Class of Networks in Focus to "Network Types in Focus" and removed abbreviations C0, C1 and C2 for network classes as they have not been used. o Changed requirement priority classes to be High, Medium and Low. o Changed requirement types to be Functional and Non-Functional and added text to explain the requirement types. o Reformulation of some text parts for more clarity. D.2. draft-ersue-constrained-mgmt-02-03 o Extended the terminology section and removed some of the terminology addressed in the new LWIG terminology draft. Referenced the LWIG terminology draft. o Moved Section 1.3. on Constrained Device Classes to the new LWIG terminology draft. o Class of networks considering the different type of radio and communication technologies in use and dimensions extended. o Extended the Problem Statement in Section 2. following the requirements listed in Section 4. o Following requirements, which belong together and can be realized with similar or same kind of solutions, have been merged. * Distributed Management and Peer Configuration, * Device status monitoring and Neighbor-monitoring, Ersue, et al. Expires April 28, 2014 [Page 53] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 * Passive Monitoring and Reactive Monitoring, * Event-driven self-management - Self-healing and Periodic self- management, * Authentication of management systems and Authentication of managed devices, * Access control on devices and Access control on management systems, * Management of Energy Resources and Data models for energy management, * Software distribution (group-based firmware update) and Group- based provisioning. o Deleted the empty section on the gaps in network management standards, as it will be written in a separate draft. o Added links to mentioned external pages. o Added text on OMA M2M Device Classification in appendix. D.3. draft-ersue-constrained-mgmt-01-02 o Extended the terminology section. o Added additional text for the use cases concerning deployment type, network topology in use, network size, network capabilities, radio technology, etc. o Added examples for device classes in a use case. o Added additional text provided by Cao Zhen (China Mobile) for Mobile Applications and by Peter van der Stok for Building Automation. o Added the new use cases 'Advanced Metering Infrastructure' and 'MANET Concept of Operations in Military'. o Added the section 'Managing the Constrainedness of a Device or Network' discussing the needs of very constrained devices. o Added a note that the requirements in Section 3 need to be seen as standalone requirements and the current document does not recommend any profile of requirements. Ersue, et al. Expires April 28, 2014 [Page 54] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 o Added Section 3 on the detailed requirements on constrained management matched to management tasks like fault, monitoring, configuration management, Security and Access Control, Energy Management, etc. o Solved nits and added references. o Added Appendix A on the related development in other bodies. o Added Appendix B on the work in related research projects. D.4. draft-ersue-constrained-mgmt-00-01 o Splitted the section on 'Networks of Constrained Devices' into the sections 'Network Topology Options' and 'Management Topology Options'. o Added the use case 'Community Network Applications' and 'Mobile Applications'. o Provided a Contributors section. o Extended the section on 'Medical Applications'. o Solved nits and added references. Ersue, et al. Expires April 28, 2014 [Page 55] Internet-Draft Constrained Mgmt: PS, Rqmts October 2013 Authors' Addresses Mehmet Ersue (editor) Nokia Solutions and Networks Email: mehmet.ersue@nsn.com Dan Romascanu Avaya Email: dromasca@avaya.com Juergen Schoenwaelder Jacobs University Bremen Email: j.schoenwaelder@jacobs-university.de Ersue, et al. Expires April 28, 2014 [Page 56]