6Lo Working Group Y-G. Hong Internet-Draft Daejeon University Intended status: Informational C.G. Gomez Expires: 29 July 2022 UPC Y-H. Choi ETRI AR. Sangi Huaiyin Institute of Technology S. Chakrabarti January 2022 IPv6 over Constrained Node Networks (6lo) Applicability & Use cases draft-ietf-6lo-use-cases-12 Abstract This document describes the applicability of IPv6 over constrained node networks (6lo) and provides practical deployment examples. In addition to IEEE Std 802.15.4, various link layer technologies such as ITU-T G.9959 (Z-Wave), Bluetooth Low Energy, DECT-ULE, MS/TP, NFC, and PLC are used as examples. The document targets an audience who would like to understand and evaluate running end-to-end IPv6 over the constrained node networks for local or Internet connectivity. 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 https://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 5 July 2022. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. Hong, et al. Expires 29 July 2022 [Page 1] Internet-Draft 6lo Applicability & Use cases January 2022 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. 6lo Link layer technologies . . . . . . . . . . . . . . . . . 4 2.1. ITU-T G.9959 . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Bluetooth LE . . . . . . . . . . . . . . . . . . . . . . 4 2.3. DECT-ULE . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4. MS/TP . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.5. NFC . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.6. PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.7. Comparison between 6lo link layer technologies . . . . . 8 3. Guidelines for adopting IPv6 stack (6lo) . . . . . . . . . . 9 4. 6lo Deployment Scenarios . . . . . . . . . . . . . . . . . . 11 4.1. Wi-SUN usage of 6lo in network layer . . . . . . . . . . 11 4.2. Thread usage of 6lo in network layer . . . . . . . . . . 13 4.3. G3-PLC usage of 6lo in network layer . . . . . . . . . . 13 4.4. Netricity usage of 6lo in network layer . . . . . . . . . 14 5. 6lo Use Case Examples . . . . . . . . . . . . . . . . . . . . 15 5.1. Use case of ITU-T G.9959: Smart Home . . . . . . . . . . 15 5.2. Use case of Bluetooth LE: Smartphone-based Interaction . 16 5.3. Use case of DECT-ULE: Smart Home . . . . . . . . . . . . 17 5.4. Use case of MS/TP: Building Automation Networks . . . . . 17 5.5. Use case of NFC: Alternative Secure Transfer . . . . . . 18 5.6. Use case of PLC: Smart Grid . . . . . . . . . . . . . . . 19 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 9. Informative References . . . . . . . . . . . . . . . . . . . 20 Appendix A. Design Space Dimensions for 6lo Deployment . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 1. Introduction Running IPv6 on constrained node networks presents challenges, due to the characteristics of these networks such as small packet size, low power, low bandwidth, low cost, and large number of devices, among others [RFC4919][RFC7228]. For example, many IEEE Std 802.15.4 variants [IEEE802154] exhibit a frame size of 127 octets, whereas IPv6 requires its underlying layer to support an MTU of 1280 bytes. Hong, et al. Expires 29 July 2022 [Page 2] Internet-Draft 6lo Applicability & Use cases January 2022 Furthermore, those IEEE Std 802.15.4 variants do not offer fragmentation and reassembly functionality. (It is noted that IEEE Std 802.15.9-2016 provides multiplexing and fragmentation layer for the IEEE Std 802.15.4[IEEE802159].) Therefore, an appropriate adaptation layer supporting fragmentation and reassembly must be provided below IPv6. Also, the limited IEEE Std 802.15.4 frame size and low energy consumption requirements motivate the need for packet header compression. The IETF IPv6 over Low-Power WPAN (6LoWPAN) working group published a suite of specification that provide an adaptation layer to support IPv6 over IEEE Std 802.15.4 comprising the following functionality: * Fragmentation and reassembly, address autoconfiguration, and a frame format [RFC4944], * IPv6 (and UDP) header compression [RFC6282], * Neighbor Discovery Optimization for 6LoWPAN [RFC6775][RFC8505]. As Internet of Things (IoT) services become more popular, the IETF 6lo working group [IETF_6lo] has defined adaptation layer functionality to support IPv6 over various link layer technologies other than IEEE Std 802.15.4, such as Bluetooth Low Energy (Bluetooth LE), ITU-T G.9959 (Z-Wave), Digital Enhanced Cordless Telecommunications - Ultra Low Energy (DECT-ULE), Master-Slave/Token Passing (MS/TP), Near Field Communication (NFC), and Power Line Communication (PLC). The 6lo adaptation layers use a variation of the 6LoWPAN stack applied to each particular link layer technology. The 6LoWPAN working group produced the document entitled "Design and Application Spaces for 6LoWPANs" [RFC6568], which describes potential application scenarios and use cases for low-power wireless personal area networks. The present document aims to provide guidance to an audience who are new to the IPv6 over constrained node networks (6lo) concept and want to assess its application to the constrained node network of their interest. This 6lo applicability document describes a few sets of practical 6lo deployment scenarios and use cases examples. In addition, it considers various network design space dimensions such as deployment, network size, power source, connectivity, multi-hop communication, traffic pattern, security level, mobility, and QoS requirements etc. This document provides the applicability and use cases of 6lo, considering the following aspects: * It covers various IoT-related wired/wireless link layer technologies providing practical information of such technologies. Hong, et al. Expires 29 July 2022 [Page 3] Internet-Draft 6lo Applicability & Use cases January 2022 * It provides a general guideline on how the 6LoWPAN stack can be modified for a given L2 technology. * Various 6lo use cases and practical deployment examples are described. 2. 6lo Link layer technologies 2.1. ITU-T G.9959 The ITU-T G.9959 Recommendation [G.9959] targets low-power Wireless Personal Area Networks (WPANs), and defines physical layer and link layer functionality. Physical layers of 9.6 kbit/s, 40 kbit/s and 100 kbit/s are supported. G.9959 defines how a unique 32-bit HomeID network identifier is assigned by a network controller and how an 8-bit NodeID host identifier is allocated to each node. NodeIDs are unique within the network identified by the HomeID. The G.9959 HomeID represents an IPv6 subnet that is identified by one or more IPv6 prefixes [RFC7428]. The ITU-T G.9959 can be used for smart home applications. 2.2. Bluetooth LE Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth 4.1, and developed further in successive versions. Bluetooth SIG has also published the Internet Protocol Support Profile (IPSP). The IPSP enables discovery of IP-enabled devices and establishment of link-layer connection for transporting IPv6 packets. IPv6 over Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or newer. Many devices such as mobile phones, notebooks, tablets and other handheld computing devices which support Bluetooth 4.0 or subsequent versions also support the low-energy variant of Bluetooth. Bluetooth LE is also being included in many different types of accessories that collaborate with mobile devices. An example of a use case for a Bluetooth LE accessory is a heart rate monitor that sends data via the mobile phone to a server on the Internet [RFC7668]. A typical usage of Bluetooth LE is smartphone-based interaction with constrained devices. Bluetooth LE was originally designed to enable star topology networks. However, recent Bluetooth versions support the formation of extended topologies, and IPv6 support for mesh networks of Bluetooth LE devices is being developed [RFC9159]. Hong, et al. Expires 29 July 2022 [Page 4] Internet-Draft 6lo Applicability & Use cases January 2022 2.3. DECT-ULE DECT-ULE is a low power air interface technology that is designed to support both circuit switched services, such as voice communication, and packet mode data services at modest data rate. The DECT-ULE protocol stack consists of the physical layer operating at frequencies in the dedicated 1880 - 1920 MHz frequency band depending on the region and uses a symbol rate of 1.152 Mbps. Radio bearers are allocated by use of FDMA/TDMA/TDD techniques. In its generic network topology, DECT is defined as a cellular network technology. However, the most common configuration is a star network with a single Fixed Part (FP) defining the network with a number of Portable Parts (PP) attached. The Medium Access Control (MAC) layer supports traditional DECT as this is used for services like discovery, pairing, security features etc. All these features have been reused from DECT. The DECT-ULE device can switch to the ULE mode of operation, utilizing the new ULE MAC layer features. The DECT-ULE Data Link Control (DLC) provides multiplexing as well as segmentation and re- assembly for larger packets from layers above. The DECT-ULE layer also implements per-message authentication and encryption. The DLC layer ensures packet integrity and preserves packet order, but delivery is based on best effort. The current DECT-ULE MAC layer standard supports low bandwidth data broadcast. However the usage of this broadcast service has not yet been standardized for higher layers [RFC8105]. DECT-ULE can be used for smart metering in a home. 2.4. MS/TP MS/TP is a MAC protocol for the RS-485 [TIA-485-A] physical layer and is used primarily in building automation networks. An MS/TP device is typically based on a low-cost microcontroller with limited processing power and memory. These constraints, together with low data rates and a small MAC address space, are similar to those faced in 6LoWPAN networks. MS/TP differs significantly from 6LoWPAN in at least three respects: a) MS/TP devices are typically mains powered, b) all MS/TP devices on a segment can communicate directly so there are no hidden node or mesh routing issues, and c) the latest MS/TP specification provides support for large payloads, eliminating the need for fragmentation and reassembly below IPv6. Hong, et al. Expires 29 July 2022 [Page 5] Internet-Draft 6lo Applicability & Use cases January 2022 MS/TP is designed to enable multidrop networks over shielded twisted pair wiring. It can support network segments up to 1000 meters in length at a data rate of 115.2 kbit/s or segments up to 1200 meters in length at lower bit rates. An MS/TP interface requires only a Universal Asynchronous Receiver-Transmitter (UART), an RS-485 [TIA-485-A] transceiver with a driver that can be disabled, and a 5 ms resolution timer. The MS/TP MAC is typically implemented in software. Because of its superior "range" (~1 km) compared to many low power wireless data links, MS/TP may be suitable to connect remote devices (such as district heating controllers) to the nearest building control infrastructure over a single link [RFC8163]. 2.5. NFC NFC technology enables simple and safe two-way interactions between electronic devices, allowing consumers to perform contactless transactions, access digital content, and connect electronic devices with a single touch. NFC complements many popular consumer level wireless technologies, by utilizing the key elements in existing standards for contactless card technology (ISO/IEC 14443 A&B and JIS-X 6319-4). Extending the capability of contactless card technology, NFC also enables devices to share information at a distance that is less than 10 cm with a maximum communication speed of 424 kbps. Users can share business cards, make transactions, access information from a smart poster or provide credentials for access control systems with a simple touch. NFC's bidirectional communication ability is ideal for establishing connections with other technologies by the simplicity of touch. In addition to the easy connection and quick transactions, simple data sharing is also available [I-D.ietf-6lo-nfc]. NFC can be used for secure transfer in healthcare services. 2.6. PLC PLC is a data transmission technique that utilizes power conductors as medium [I-D.ietf-6lo-plc]. Unlike other dedicated communication infrastructure, power conductors are widely available indoors and outdoors. Moreover, wired technologies cause less interference to the radio medium than wireless technologies and are more reliable than their wireless counterparts. The below table shows some available open standards defining PLC. Hong, et al. Expires 29 July 2022 [Page 6] Internet-Draft 6lo Applicability & Use cases January 2022 +=============+=================+============+===========+==========+ | PLC Systems | Frequency Range | Type | Data | Distance | | | | | Rate | | +=============+=================+============+===========+==========+ | IEEE1901 | <100MHz | Broadband | 200Mbps | 1000m | +-------------+-----------------+------------+-----------+----------+ | IEEE1901.1 | <12MHz | PLC-IoT | 10Mbps | 2000m | +-------------+-----------------+------------+-----------+----------+ | IEEE1901.2 | <500kHz | Narrowband | 200kbps | 3000m | +-------------+-----------------+------------+-----------+----------+ | G3-PLC | <500kHz | Narrowband | 234kbps | 3000m | +-------------+-----------------+------------+-----------+----------+ Table 1: Some Available Open Standards in PLC IEEE Std 1901 [IEEE1901] defines a broadband variant of PLC but is effective within short range. This standard addresses the requirements of applications with high data rate such as: Internet, HDTV, Audio, Gaming etc. Broadband operates on Orthogonal Frequency Division Multiplexing (OFDM) modulation. IEEE Std 1901.1 [IEEE1901.1] defines a medium frequency band (less than 12 MHz) broadband PLC technology for smart grid applications based on OFDM. By achieving an extended communication range with medium speeds, this standard can be applied both in indoor and outdoor scenarios, such as Advanced Metering Infrastructure (AMI), street lighting, electric vehicle charging, smart city etc. IEEE Std 1901.2 [IEEE1901.2] defines a narrowband variant of PLC with less data rate but significantly higher transmission range that could be used in an indoor or even an outdoor environment. It is applicable to typical IoT applications such as: Building Automation, Renewable Energy, Advanced Metering, Street Lighting, Electric Vehicle, Smart Grid etc. Moreover, IEEE Std 1901.2 standard is based on the 802.15.4 MAC sub-layer and fully endorses the security scheme defined in 802.15.4 [RFC8036]. A typical use case of PLC is smart grid. G3-PLC [G3-PLC] is a narrowband PLC technology that is based on the ITU-T G.9903 Recommendation [G.9903]. The ITU-T G.9903 Recommendation contains the physical layer and data link layer specification for the G3-PLC narrowband OFDM power line communication transceivers, for communications via alternating current and direct current electric power lines over frequencies below 500 kHz. Hong, et al. Expires 29 July 2022 [Page 7] Internet-Draft 6lo Applicability & Use cases January 2022 2.7. Comparison between 6lo link layer technologies In above clauses, various 6lo link layer technologies are described. The following table shows dominant parameters of each use case corresponding to the 6lo link layer technology. +--------------+---------+---------+---------+---------+---------+---------+ | | Z-Wave | BLE | DECT-ULE| MS/TP | NFC | PLC | +--------------+---------+---------+---------+---------+---------+---------+ | | Home | Interact| | Building| Health- | | | Usage | Auto- | w/ Smart| Meter | Auto- | care | Smart | | | mation | Phone | Reading | mation | Service | Grid | +--------------+---------+---------+---------+---------+---------+---------+ | Topology | L2-mesh | Star | Star | MS/TP | P2P | Star | | & | or | & | | | | Tree | | Subnet | L3-mesh | Mesh | No mesh | No mesh | L2-mesh | Mesh | +--------------+---------+---------+---------+---------+---------+---------+ | | | | | | | | | Mobility | No | Low | No | No | Moderate| No | | Requirement | | | | | | | +--------------+---------+---------+---------+---------+---------+---------+ | | High + | | High + | High + | | High + | | Security | Privacy |Partially| Privacy | Authen. | High | Encrypt.| | Requirement | required| | required| required| | required| +--------------+---------+---------+---------+---------+---------+---------+ | | | | | | | | | Buffering | Low | Low | Low | Low | Low | Low | | Requirement | | | | | | | +--------------+---------+---------+---------+---------+---------+---------+ | Latency, | | | | | | | | QoS | High | Low | Low | High | High | Low | | Requirement | | | | | | | +--------------+---------+---------+---------+---------+---------+---------+ | | | | | | | | | Data | Infrequ-| Infrequ-| Infrequ-| Frequent| Small | Infrequ-| | Rate | ent | ent | ent | | | ent | +--------------+---------+---------+---------+---------+---------+---------+ | RFC # | | | | | draft- | draft- | | or | RFC7428 | RFC7668,| RFC8105 | RFC8163 | ietf-6lo| ietf-6lo| | Draft | | RFC9159 | | | -nfc | -plc | +--------------+---------+---------+---------+---------+---------+---------+ Table 2: Comparison between 6lo link layer technologies Hong, et al. Expires 29 July 2022 [Page 8] Internet-Draft 6lo Applicability & Use cases January 2022 3. Guidelines for adopting IPv6 stack (6lo) 6lo aims at reusing and/or adapting existing 6LoWPAN functionality in order to efficiently support IPv6 over a variety of IoT L2 technologies. The following guideline targets new candidate constrained L2 technologies that may be considered for running a modified 6LoWPAN stack on top. The modification of 6LoWPAN stack should be based on the following: * Addressing Model: Addressing model determines whether the device is capable of forming IPv6 link-local and global addresses and what is the best way to derive the IPv6 addresses for the constrained L2 devices. L2-address-derived IPv6 addresses are specified in [RFC4944], but there exist implications for privacy. For global usage, a unique IPv6 address must be derived using an assigned prefix and a unique interface ID. [RFC8065] provides such guidelines. For MAC-derived IPv6 addresses, please refer to [RFC8163] for IPv6 address mapping examples. Broadcast and multicast support are dependent on the L2 networks. Most low- power L2 implementations map multicast to broadcast networks. So care must be taken in the design when to use broadcast and try to stick to unicast messaging whenever possible. * MTU Considerations: The deployment should consider packet maximum transmission unit (MTU) needs over the link layer and should consider if fragmentation and reassembly of packets are needed at the 6LoWPAN layer. For example, if the link layer supports fragmentation and reassembly of packets, then the 6LoWPAN layer may not need to support fragmentation/reassembly. In fact, for most efficiency, choosing a low-power link layer that can carry unfragmented application packets would be optimum for packet transmission if the deployment can afford it. Please refer to 6lo RFCs [RFC7668], [RFC8163], [RFC8105] for example guidance. * Mesh or L3-Routing: 6LoWPAN specifications provide mechanisms to support mesh routing at L2, a configuration called mesh-under [RFC6606]. It is also possible to use an L3 routing protocol in 6LoWPAN, an approach known as route-over. [RFC6550] defines RPL, a L3 routing protocol for low power and lossy networks using directed acyclic graphs. 6LoWPAN is routing-protocol-agnostic and does not specify any particular L2 or L3 routing protocol to use with a 6LoWPAN stack. * Address Assignment: 6LoWPAN developed a new version of IPv6 Neighbor Discovery [RFC4861][RFC4862]. 6LoWPAN Neighbor Discovery [RFC6775][RFC8505] inherits from IPv6 Neighbor Discovery for mechanisms such as Stateless Address Autoconfiguration (SLAAC) and Neighbor Unreachability Detection (NUD). A 6LoWPAN node is also Hong, et al. Expires 29 July 2022 [Page 9] Internet-Draft 6lo Applicability & Use cases January 2022 expected to be an IPv6 host per [RFC8200] which means it should ignore consumed routing headers and Hop-by-Hop options; when operating in a RPL network [RFC6550], it is also beneficial to support IP-in-IP encapsulation [RFC9008]. The 6LoWPAN node should also support [RFC8505] and use it as the default Neighbor Discovery method. It is the responsibility of the deployment to ensure unique global IPv6 addresses for Internet connectivity. For local-only connectivity IPv6 Unique Local Address (ULA) may be used. [RFC6775][RFC8505] specifies the 6LoWPAN border router (6LBR), which is responsible for prefix assignment to the 6LoWPAN network. A 6LBR can be connected to the Internet or to an enterprise network via one of the interfaces. Please refer to [RFC7668] and [RFC8105] for examples of address assignment considerations. In addition, privacy considerations [RFC8065] must be consulted for applicability. In certain scenarios, the deployment may not support IPv6 address autoconfiguration due to regulatory and business reasons and may choose to offer a separate address assignment service. Address Protection for 6LoWPAN Neighbor Discovery (AP-ND) [RFC8928] enables Source Address Validation [RFC6620] and protects the address ownership against impersonation attacks. * Broadcast Avoidance: 6LoWPAN Neighbor Discovery aims at reducing the amount of multicast traffic of classical Neighbor Discovery, since IP-level multicast translates into L2 broadcast in many L2 technologies. 6LoWPAN Neighbor Discovery relies on a proactive registration to avoid the use of multicast for address resolution. It also uses a unicast method for Duplicate Address Detection (DAD), and avoids multicast lookups from all nodes by using non- onlink prefixes. Router Advertisements (RAs) are also sent in unicast, in response to Router Solicitations (RSs) * Host-to-Router interface: 6lo has defined registration extensions for 6LoWPAN Neighbor Discovery [RFC8505]. This effort provides a host-to-router interface by which a host can request its router to ensure reachability for the address registered with the router. Note that functionality has been developed to ensure that such a host can benefit from routing services in a RPL network [RFC9010] * Proxy Neighbor Discovery: Further functionality also allows a device (e.g. an energy-constrained device that needs to sleep most of the time) to request proxy Neighbor Discovery services from a 6LoWPAN Backbone Router (6BBR) [RFC8505][RFC8929]. The latter federates a number of links into a multilink subnet. * Header Compression: IPv6 header compression [RFC6282] is a vital part of IPv6 over low power communication. Examples of header compression over different link-layer specifications are found in Hong, et al. Expires 29 July 2022 [Page 10] Internet-Draft 6lo Applicability & Use cases January 2022 [RFC7668], [RFC8163], [RFC8105]. A generic header compression technique is specified in [RFC7400]. For 6LoWPAN networks where RPL is the routing protocol, there exist 6LoWPAN header compression extensions which allow to compress also the RPL artifacts used when forwarding packets in the route-over mesh [RFC8138] [RFC9035] * Security and Encryption: Though 6LoWPAN basic specifications do not address security at the network layer, the assumption is that L2 security must be present. In addition, application-level security is highly desirable. The working groups [IETF_ace] and [IETF_core] should be consulted for application and transport level security. 6lo working group is working on address authentication [RFC8928] and secure bootstrapping is also being discussed at IETF. However, there may be different levels of security available in a deployment through other standards such as hardware-level security or certificates for initial booting process. Encryption is important if the implementation can afford it. * Additional processing: [RFC8066] defines guidelines for ESC dispatch octets use in the 6LoWPAN header. An implementation may take advantage of ESC header to offer a deployment specific processing of 6LoWPAN packets. 4. 6lo Deployment Scenarios 4.1. Wi-SUN usage of 6lo in network layer Wireless Smart Ubiquitous Network (Wi-SUN)[Wi-SUN] is a technology based on the IEEE Std 802.15.4g standard. Wi-SUN networks support star and mesh topologies, as well as hybrid star/mesh deployments, but these are typically laid out in a mesh topology where each node relays data for the network to provide network connectivity. Wi-SUN networks are deployed on both powered and battery-operated devices [RFC8376]. The main application domains targeted by Wi-SUN are smart utility and smart city networks. This includes, but is not limited to the following applications: * Advanced Metering Infrastructure * Distribution Automation * Home Energy Management * Infrastructure Management Hong, et al. Expires 29 July 2022 [Page 11] Internet-Draft 6lo Applicability & Use cases January 2022 * Intelligent Transportation Systems * Smart Street Lighting * Agriculture * Structural health (bridges, buildings) * Monitoring and Asset Management * Smart Thermostats, Air Conditioning and Heat Controls * Energy Usage Information Displays The Wi-SUN Alliance Field Area Network (FAN) covers primarily outdoor networks, and its specification is oriented towards meeting the more rigorous challenges of these environments. It has the following features: * Open standards based on IEEE802, IETF, TIA, ETSI * Architecture based on an IPv6 frequency hopping wireless mesh network with enterprise-level security * Simple infrastructure of low cost, low complexity * Enhanced network robustness, reliability, and resilience to interference, due to high redundancy and frequency hopping * Enhanced scalability, long range, and energy friendliness * Supports multiple global license-exempt sub-GHz bands * Multi-vendor interoperability * Very low power modes in development permitting long term battery operation of network nodes The Wi-SUN FAN specification defines an IPv6-based protocol suite including TCP/UDP, IPv6, 6lo adaptation layer, DHCPv6 for IPv6 address management, RPL, and ICMPv6. Hong, et al. Expires 29 July 2022 [Page 12] Internet-Draft 6lo Applicability & Use cases January 2022 4.2. Thread usage of 6lo in network layer Thread is an IPv6-based networking protocol stack built on open standards, designed for smart home environments, and based on low- power IEEE Std 802.15.4 mesh networks. Because of its IPv6 foundation, Thread can support existing popular application layers and IoT platforms, provide end-to-end security, ease development and enable flexible and future-proof designs [Thread]. The Thread specification uses the IEEE Std 802.15.4 [IEEE802154] physical and MAC layers operating at 250 kbps in the 2.4 GHz band. Thread devices use 6LoWPAN, as defined in [RFC4944][RFC6282], for transmission of IPv6 Packets over IEEE Std 802.15.4 networks. Header compression is used within the Thread network and devices transmitting messages compress the IPv6 header to minimize the size of the transmitted packet. The mesh header is supported for link- layer (i.e., mesh under) forwarding. The mesh header as used in Thread also allows efficient end-to-end fragmentation of messages rather than the hop-by-hop fragmentation specified in [RFC4944]. Mesh under routing in Thread is based on a distance vector protocol in a full mesh topology. 4.3. G3-PLC usage of 6lo in network layer G3-PLC [G3-PLC] is a narrowband PLC technology that is based on the ITU-T G.9903 Recommendation [G.9903]. G3-PLC supports multi-hop mesh network topology, and facilitates highly-reliable, long-range communication. With the abilities to support IPv6 and to cross transformers, G3-PLC is regarded as one of the next-generation narrowband PLC technologies. G3-PLC has got massive deployments over several countries, e.g. Japan and France. The main application domains targeted by G3-PLC are smart grid and smart cities. This includes, but is not limited to the following applications: * Smart Metering * Vehicle-to-Grid Communication * Demand Response * Distribution Automation * Home/Building Energy Management Systems * Smart Street Lighting Hong, et al. Expires 29 July 2022 [Page 13] Internet-Draft 6lo Applicability & Use cases January 2022 * Advanced Metering Infrastructure (AMI) backbone network * Wind/Solar Farm Monitoring In the G3-PLC specification, the 6lo adaption layer utilizes the 6LoWPAN functions (e.g. header compression, fragmentation and reassembly). However, due to the different characteristics of the PLC media, the 6LoWPAN adaptation layer cannot perfectly fulfill the requirements [I-D.ietf-6lo-plc]. The ESC dispatch type is used in the G3-PLC to provide native mesh routing and bootstrapping functionalities [RFC8066]. 4.4. Netricity usage of 6lo in network layer The Netricity program in HomePlug Powerline Alliance [NETRICITY] promotes the adoption of products built on the IEEE Std 1901.2 low- frequency narrowband PLC standard, which provides for urban and long distance communications and propagation through transformers of the distribution network using frequencies below 500 kHz. The technology also addresses requirements that assure communication privacy and secure networks. The main application domains targeted by Netricity are smart grid and smart cities. This includes, but is not limited to the following applications: * Utility grid modernization * Distribution automation * Meter-to-Grid connectivity * Micro-grids * Grid sensor communications * Load control * Demand response * Net metering * Street Lighting control * Photovoltaic panel monitoring Hong, et al. Expires 29 July 2022 [Page 14] Internet-Draft 6lo Applicability & Use cases January 2022 Netricity system architecture is based on the physical and MAC layers of IEEE Std 1901.2 PLC standard. Regarding the 6lo adaptation layer and IPv6 network layer, Netricity utilizes IPv6 protocol suite including 6lo/6LoWPAN header compression, DHCPv6 for IP address management, RPL routing protocol, ICMPv6, and unicast/multicast forwarding. Note that the L3 routing in Netricity uses RPL in non- storing mode with the MRHOF objective function based on the own defined Estimated Transmission Time (ETT) metric. 5. 6lo Use Case Examples As IPv6 stacks for constrained node networks use a variation of the 6LoWPAN stack applied to each particular link layer technology, various 6lo use cases can be provided. In this section, various 6lo use cases which are based on different link layer technologies are described. 5.1. Use case of ITU-T G.9959: Smart Home Z-Wave is one of the main technologies that may be used to enable smart home applications. Born as a proprietary technology, Z-Wave was specifically designed for this particular use case. Recently, the Z-Wave radio interface (physical and MAC layers) has been standardized as the ITU-T G.9959 specification. Example: Use of ITU-T G.9959 for Home Automation Variety of home devices (e.g. light dimmers/switches, plugs, thermostats, blinds/curtains and remote controls) are augmented with ITU-T G.9959 interfaces. A user may turn on/off or may control home appliances by pressing a wall switch or by pressing a button in a remote control. Scenes may be programmed, so that after a given event, the home devices adopt a specific configuration. Sensors may also periodically send measurements of several parameters (e.g. gas presence, light, temperature, humidity, etc.) which are collected at a sink device, or may generate commands for actuators (e.g. a smoke sensor may send an alarm message to a safety system). Hong, et al. Expires 29 July 2022 [Page 15] Internet-Draft 6lo Applicability & Use cases January 2022 The devices involved in the described scenario are nodes of a network that follows the mesh topology, which is suitable for path diversity to face indoor multipath propagation issues. The multihop paradigm allows end-to-end connectivity when direct range communication is not possible. Security support is required, specially for safety-related communication. When a user interaction (e.g. a button press) triggers a message that encapsulates a command, if the message is lost, the user may have to perform further interactions to achieve the desired effect (e.g. turning off a light). A reaction to a user interaction will be perceived by the user as immediate as long as the reaction takes place within 0.5 seconds [RFC5826]. 5.2. Use case of Bluetooth LE: Smartphone-based Interaction The key feature behind the current high Bluetooth LE momentum is its support in a large majority of smartphones in the market. Bluetooth LE can be used to allow the interaction between the smartphone and surrounding sensors or actuators. Furthermore, Bluetooth LE is also the main radio interface currently available in wearables. Since a smartphone typically has several radio interfaces that provide Internet access, such as Wi-Fi or 4G, the smartphone can act as a gateway for nearby devices such as sensors, actuators or wearables. Bluetooth LE may be used in several domains, including healthcare, sports/wellness and home automation. Example: Use of Bluetooth LE-based Body Area Network for fitness A person wears a smartwatch for fitness purposes. The smartwatch has several sensors (e.g. heart rate, accelerometer, gyrometer, GPS, temperature, etc.), a display, and a Bluetooth LE radio interface. The smartwatch can show fitness-related statistics on its display. However, when a paired smartphone is in the range of the smartwatch, the latter can report almost real-time measurements of its sensors to the smartphone, which can forward the data to a cloud service on the Internet. 6lo enables this use case by providing efficient end-to-end IPv6 support. In addition, the smartwatch can receive notifications (e.g. alarm signals) from the cloud service via the smartphone. On the other hand, the smartphone may locally generate messages for the smartwatch, such as e-mail reception or calendar notifications. The functionality supported by the smartwatch may be complemented by other devices such as other on-body sensors, wireless headsets or head-mounted displays. All such devices may connect to the smartphone creating a star topology network whereby the smartphone is the central component. Support for extended network topologies (e.g. mesh networks) is being developed as of the writing. Hong, et al. Expires 29 July 2022 [Page 16] Internet-Draft 6lo Applicability & Use cases January 2022 5.3. Use case of DECT-ULE: Smart Home DECT is a technology widely used for wireless telephone communications in residential scenarios. Since DECT-ULE is a low- power variant of DECT, DECT-ULE can be used to connect constrained devices such as sensors and actuators to a Fixed Part, a device that typically acts as a base station for wireless telephones. Therefore, DECT-ULE is specially suitable for the connected home space in application areas such as home automation, smart metering, safety, healthcare, etc. Since DECT-ULE uses dedicated bandwidth, it avoids the coexistence issues suffered by other technologies that use e.g. ISM frequency bands. Example: Use of DECT-ULE for Smart Metering The smart electricity meter of a home is equipped with a DECT-ULE transceiver. This device is in the coverage range of the Fixed Part of the home. The Fixed Part can act as a router connected to the Internet. This way, the smart meter can transmit electricity consumption readings through the DECT-ULE link with the Fixed Part, and the latter can forward such readings to the utility company using Wide Area Network (WAN) links. The meter can also receive queries from the utility company or from an advanced energy control system controlled by the user, which may also be connected to the Fixed Part via DECT-ULE. 5.4. Use case of MS/TP: Building Automation Networks The primary use case for IPv6 over MS/TP (6LoBAC) is in building automation networks. [BACnet] is the open international standard protocol for building automation, and MS/TP is defined in [BACnet] Clause 9. MS/TP was designed to be a low cost multi-drop field bus to inter-connect the most numerous elements (sensors and actuators) of a building automation network to their controllers. A key aspect of 6LoBAC is that it is designed to co-exist with BACnet MS/TP on the same link, easing the ultimate transition of some BACnet networks to native end-to-end IPv6 transport protocols. New applications for 6LoBAC may be found in other domains where low cost, long distance, and low latency are required. Note that BACnet comprises various networking solutions other than MS/TP, including the recently emerged BACnet IP. However, the latter is based on high speed Ethernet infrastructure, and thus it falls outside of the constrained node network scope. Example: Use of 6LoBAC in Building Automation Networks Hong, et al. Expires 29 July 2022 [Page 17] Internet-Draft 6lo Applicability & Use cases January 2022 The majority of installations for MS/TP are for "terminal" or "unitary" controllers, i.e. single zone or room controllers that may connect to HVAC or other controls such as lighting or blinds. The economics of daisy-chaining a single twisted-pair between multiple devices is often preferred over home-run Cat-5 style wiring. A multi-zone controller might be implemented as an IP router between a traditional Ethernet link and several 6LoBAC links, fanning out to multiple terminal controllers. The superior distance capabilities of MS/TP (~1 km) compared to other 6lo media may suggest its use in applications to connect remote devices to the nearest building infrastructure. For example, remote pumping or measuring stations with moderate bandwidth requirements can benefit from the low cost and robust capabilities of MS/TP over other wired technologies such as DSL, and without the line-of-sight restrictions or hop-by-hop latency of many low cost wireless solutions. 5.5. Use case of NFC: Alternative Secure Transfer In different applications, a variety of secured data can be handled and transferred. Depending on the security level of the data, different transfer methods can be alternatively selected. Example: Use of NFC for Secure Transfer in Healthcare Services with Tele-Assistance A senior citizen who lives alone wears one to several wearable 6lo devices to measure heartbeat, pulse rate, etc. The 6lo devices are densely installed at home for movement detection. A 6LBR at home will send the sensed information to a connected healthcare center. Portable base stations with LCDs may be used to check the data at home, as well. Data is gathered in both periodic and event-driven fashion. In this application, event-driven data can be very time- critical. In addition, privacy also becomes a serious issue in this case, as the sensed data is very personal. While the senior citizen is provided audio and video healthcare services by a tele-assistance based on LTE connections, the senior citizen can alternatively use NFC connections to transfer the personal sensed data to the tele-assistance. Hidden hackers can overhear the data based on the LTE connection, but they cannot gather the personal data over the NFC connection. Hong, et al. Expires 29 July 2022 [Page 18] Internet-Draft 6lo Applicability & Use cases January 2022 5.6. Use case of PLC: Smart Grid The smart grid concept is based on deploying numerous operational and energy measuring sub-systems in an electricity grid system. It comprises multiple administrative levels/segments to provide connectivity among these numerous components. Last mile connectivity is established over the Low Voltage (LV) segment, whereas connectivity over electricity distribution takes place in the High Voltage (HV) segment. Smart grid systems include Advanced Metering Infrastructure (AMI), Demand Response (DR), Home Energy Management System (HEMS), Wide Area Situational Awareness (WASA), among others. Although other wired and wireless technologies are also used in Smart Grid, PLC enjoys the advantage of reliable data communication over electrical power lines that are already present, and the deployment cost can be comparable to wireless technologies. The 6lo-related scenarios for PLC mainly lie in the LV PLC networks with most applications in the area of Advanced Metering Infrastructure, Vehicle-to-Grid communications, in-home energy management and smart street lighting. Example: Use of PLC for Advanced Metering Infrastructure Household electricity meters transmit time-based data of electric power consumption through PLC. Data concentrators receive all the meter data in their corresponding living districts and send them to the Meter Data Management System (MDMS) through WAN network (e.g. Medium-Voltage PLC, Ethernet or GPRS) for storage and analysis. Two- way communications are enabled which means smart meters can do actions like notification of electricity charges according to the commands from the utility company. With the existing power line infrastructure as communication medium, cost on building up the PLC network is naturally saved, and more importantly, labor operational costs can be minimized from a long- term perspective. Furthermore, this AMI application speeds up electricity charge, reduces losses by restraining power theft and helps to manage the health of the grid based on line loss analysis. Example: Use of PLC (IEEE Std 1901.1) for WASA in Smart Grid Many sub-systems of Smart Grid require low data rate and narrowband variants (e.g., IEEE Std 1901.1) of PLC fulfill such requirements. Recently, more complex scenarios are emerging that require higher data rates. Hong, et al. Expires 29 July 2022 [Page 19] Internet-Draft 6lo Applicability & Use cases January 2022 WASA sub-system is an appropriate example that collects large amount of information about the current state of the grid over wide area from electric substations as well as power transmission lines. The collected feedback is used for monitoring, controlling and protecting all the sub-systems. 6. IANA Considerations There are no IANA considerations related to this document. 7. Security Considerations Security considerations are not directly applicable to this document. For the use cases, the security requirements described in the protocol specifications apply. 8. Acknowledgements Carles Gomez has been funded in part by the Spanish Government through the Jose Castillejo CAS15/00336 grant, the TEC2016-79988-P grant, and the PID2019-106808RA-I00 grant, and by Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya 2017 through grant SGR 376. His contribution to this work has been carried out in part during his stay as a visiting scholar at the Computer Laboratory of the University of Cambridge. Thomas Watteyne, Pascal Thubert, Xavier Vilajosana, Daniel Migault, Jianqiang Hou, Kerry Lynn, S.V.R. Anand, and Seyed Mahdi Darroudi have provided valuable feedback for this draft. Das Subir and Michel Veillette have provided valuable information of jupiterMesh and Paul Duffy has provided valuable information of Wi- SUN for this draft. Also, Jianqiang Hou has provided valuable information of G3-PLC and Netricity for this draft. Take Aanstoot, Kerry Lynn, and Dave Robin have provided valuable information of MS/ TP and practical use case of MS/TP for this draft. Deoknyong Ko has provided relevant text of LTE-MTC and he shared his experience to deploy IPv6 and 6lo technologies over LTE MTC in SK Telecom. 9. Informative References Hong, et al. Expires 29 July 2022 [Page 20] Internet-Draft 6lo Applicability & Use cases January 2022 [BACnet] "ASHRAE, "BACnet-A Data Communication Protocol for Building Automation and Control Networks", ANSI/ASHRAE Standard 135-2016", January 2016, . [G.9903] "International Telecommunication Union, "Narrowband orthogonal frequency division multiplexing power line communication transceivers for G3-PLC networks", ITU-T Recommendation", August 2017. [G.9959] "International Telecommunication Union, "Short range narrow-band digital radiocommunication transceivers - PHY and MAC layer specifications", ITU-T Recommendation", January 2015. [G3-PLC] "G3-PLC Alliance", . [IEEE1901] "IEEE Standard, IEEE Std 1901-2010 - IEEE Standard for Broadband over Power Line Networks: Medium Access Control and Physical Layer Specifications", 2010, . [IEEE1901.1] "IEEE Standard, IEEE Std 1901.1-2018 - IEEE Standard for Medium Frequency (less than 12 MHz) Power Line Communications for Smart Grid Applications", 2018, . [IEEE1901.2] "IEEE Standard, IEEE Std 1901.2-2013 - IEEE Standard for Low-Frequency (less than 500 kHz) Narrowband Power Line Communications for Smart Grid Applications", 2013, . [IEEE802154] IEEE standard for Information Technology, "IEEE Standard for Low-Rate Wireless Networks". [IEEE802159] IEEE standard for Information Technology, "IEEE Std 802.15.9-2016 - IEEE Recommended Practice for Transport of Key Management Protocol (KMP) Datagrams". Hong, et al. Expires 29 July 2022 [Page 21] Internet-Draft 6lo Applicability & Use cases January 2022 [I-D.ietf-6lo-nfc] Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi, "Transmission of IPv6 Packets over Near Field Communication", Work in Progress, Internet-Draft, draft- ietf-6lo-nfc-17, 23 August 2020, . [I-D.ietf-6lo-plc] Hou, J., Liu, B. R., Hong, Y., Tang, X., and C. E. Perkins, "Transmission of IPv6 Packets over PLC Networks", Work in Progress, Internet-Draft, draft-ietf-6lo-plc-09, 10 January 2022, . [IETF_6lo] "IETF IPv6 over Networks of Resource-constrained Nodes (6lo) working group", . [IETF_ace] "IETF Authentication and Authorization for Constrained Environments (ace) working group", . [IETF_core] "IETF Constrained RESTful Environments (core) working group", . [Wi-SUN] "Wi-SUN Alliance", . [Thread] "Thread Group", . [NETRICITY] "Netricity program in HomePlug Powerline Alliance", . [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007, . [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, DOI 10.17487/RFC4862, September 2007, . Hong, et al. Expires 29 July 2022 [Page 22] Internet-Draft 6lo Applicability & Use cases January 2022 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals", RFC 4919, DOI 10.17487/RFC4919, August 2007, . [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, . [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation Routing Requirements in Low-Power and Lossy Networks", RFC 5826, DOI 10.17487/RFC5826, April 2010, . [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, DOI 10.17487/RFC6282, September 2011, . [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks", RFC 6550, DOI 10.17487/RFC6550, March 2012, . [RFC6568] Kim, E., Kaspar, D., and JP. Vasseur, "Design and Application Spaces for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)", RFC 6568, DOI 10.17487/RFC6568, April 2012, . [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem Statement and Requirements for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Routing", RFC 6606, DOI 10.17487/RFC6606, May 2012, . [RFC6620] Nordmark, E., Bagnulo, M., and E. Levy-Abegnoli, "FCFS SAVI: First-Come, First-Served Source Address Validation Improvement for Locally Assigned IPv6 Addresses", RFC 6620, DOI 10.17487/RFC6620, May 2012, . Hong, et al. Expires 29 July 2022 [Page 23] Internet-Draft 6lo Applicability & Use cases January 2022 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. Bormann, "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)", RFC 6775, DOI 10.17487/RFC6775, November 2012, . [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for Constrained-Node Networks", RFC 7228, DOI 10.17487/RFC7228, May 2014, . [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 2014, . [RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets over ITU-T G.9959 Networks", RFC 7428, DOI 10.17487/RFC7428, February 2015, . [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B., Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015, . [RFC8036] Cam-Winget, N., Ed., Hui, J., and D. Popa, "Applicability Statement for the Routing Protocol for Low-Power and Lossy Networks (RPL) in Advanced Metering Infrastructure (AMI) Networks", RFC 8036, DOI 10.17487/RFC8036, January 2017, . [RFC8065] Thaler, D., "Privacy Considerations for IPv6 Adaptation- Layer Mechanisms", RFC 8065, DOI 10.17487/RFC8065, February 2017, . [RFC8066] Chakrabarti, S., Montenegro, G., Droms, R., and J. Woodyatt, "IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) ESC Dispatch Code Points and Guidelines", RFC 8066, DOI 10.17487/RFC8066, February 2017, . [RFC8105] Mariager, P., Petersen, J., Ed., Shelby, Z., Van de Logt, M., and D. Barthel, "Transmission of IPv6 Packets over Digital Enhanced Cordless Telecommunications (DECT) Ultra Low Energy (ULE)", RFC 8105, DOI 10.17487/RFC8105, May 2017, . Hong, et al. Expires 29 July 2022 [Page 24] Internet-Draft 6lo Applicability & Use cases January 2022 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, "IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, April 2017, . [RFC8163] Lynn, K., Ed., Martocci, J., Neilson, C., and S. Donaldson, "Transmission of IPv6 over Master-Slave/Token- Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163, May 2017, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . [RFC8352] Gomez, C., Kovatsch, M., Tian, H., and Z. Cao, Ed., "Energy-Efficient Features of Internet of Things Protocols", RFC 8352, DOI 10.17487/RFC8352, April 2018, . [RFC8376] Farrell, S., Ed., "Low-Power Wide Area Network (LPWAN) Overview", RFC 8376, DOI 10.17487/RFC8376, May 2018, . [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. Perkins, "Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, . [RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik, "Address-Protected Neighbor Discovery for Low-Power and Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November 2020, . [RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli, "IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929, November 2020, . [RFC9008] Robles, M.I., Richardson, M., and P. Thubert, "Using RPI Option Type, Routing Header for Source Routes, and IPv6- in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008, DOI 10.17487/RFC9008, April 2021, . Hong, et al. Expires 29 July 2022 [Page 25] Internet-Draft 6lo Applicability & Use cases January 2022 [RFC9010] Thubert, P., Ed. and M. Richardson, "Routing for RPL (Routing Protocol for Low-Power and Lossy Networks) Leaves", RFC 9010, DOI 10.17487/RFC9010, April 2021, . [RFC9035] Thubert, P., Ed. and L. Zhao, "A Routing Protocol for Low- Power and Lossy Networks (RPL) Destination-Oriented Directed Acyclic Graph (DODAG) Configuration Option for the 6LoWPAN Routing Header", RFC 9035, DOI 10.17487/RFC9035, April 2021, . [RFC9159] Gomez, C., Darroudi, S.M., Savolainen, T., and M. Spoerk, "IPv6 Mesh over BLUETOOTH(R) Low Energy Using the Internet Protocol Support Profile (IPSP)", RFC 9159, DOI 10.17487/RFC9159, December 2021, . [TIA-485-A] "TIA, "Electrical Characteristics of Generators and Receivers for Use in Balanced Digital Multipoint Systems", TIA-485-A (Revision of TIA-485)", March 2003, . Appendix A. Design Space Dimensions for 6lo Deployment The [RFC6568] lists the dimensions used to describe the design space of wireless sensor networks in the context of the 6LoWPAN working group. The design space is already limited by the unique characteristics of a LoWPAN (e.g. low power, short range, low bit rate). In [RFC6568], the following design space dimensions are described: Deployment, Network size, Power source, Connectivity, Multi-hop communication, Traffic pattern, Mobility, Quality of Service (QoS). However, in this document, the following design space dimensions are considered: * Deployment/Bootstrapping: 6lo nodes can be connected randomly, or in an organized manner. The bootstrapping has different characteristics for each link layer technology. * Topology: Topology of 6lo networks may inherently follow the characteristics of each link layer technology. Point-to-point, star, tree or mesh topologies can be configured, depending on the link layer technology considered. Hong, et al. Expires 29 July 2022 [Page 26] Internet-Draft 6lo Applicability & Use cases January 2022 * L2-Mesh or L3-Mesh: L2-mesh and L3-mesh may inherently follow the characteristics of each link layer technology. Some link layer technologies may support L2-mesh and some may not support. * Multi-link subnet, single subnet: The selection of multi-link subnet and single subnet depends on connectivity and the number of 6lo nodes. * Data rate: Typically, the link layer technologies of 6lo have low rate of data transmission. But, by adjusting the MTU, it can deliver higher upper layer data rate. * Buffering requirements: Some 6lo use case may require more data rate than the link layer technology support. In this case, a buffering mechanism to manage the data is required. * Security and Privacy Requirements: Some 6lo use case can involve transferring some important and personal data between 6lo nodes. In this case, high-level security support is required. * Mobility across 6lo networks and subnets: The movement of 6lo nodes depends on the 6lo use case. If the 6lo nodes can move or moved around, a mobility management mechanism is required. * Time synchronization requirements: The requirement of time synchronization of the upper layer service is dependent on the 6lo use case. For some 6lo use case related to health service, the measured data must be recorded with exact time and must be transferred with time synchronization. * Reliability and QoS: Some 6lo use case requires high reliability, for example real-time service or health-related services. * Traffic patterns: 6lo use cases may involve various traffic patterns. For example, some 6lo use case may require short data length and random transmission. Some 6lo use case may require continuous data and periodic data transmission. * Security Bootstrapping: Without the external operations, 6lo nodes must have the security bootstrapping mechanism. * Power use strategy: to enable certain use cases, there may be requirements on the class of energy availability and the strategy followed for using power for communication [RFC7228]. Each link layer technology defines a particular power use strategy which may be tuned [RFC8352]. Readers are expected to be familiar with [RFC7228] terminology. Hong, et al. Expires 29 July 2022 [Page 27] Internet-Draft 6lo Applicability & Use cases January 2022 * Update firmware requirements: Most 6lo use cases will need a mechanism for updating firmware. In these cases support for over the air updates are required, probably in a broadcast mode when bandwidth is low and the number of identical devices is high. * Wired vs. Wireless: Plenty of 6lo link layer technologies are wireless, except MS/TP and PLC. The selection of wired or wireless link layer technology is mainly dependent on the requirement of 6lo use cases and the characteristics of wired/ wireless technologies. For example, some 6lo use cases may require easy and quick deployment, whereas others may need a continuous source of power. Authors' Addresses Yong-Geun Hong Daejeon University 62 Daehak-ro, Dong-gu Daejeon Phone: +82 42 280 4841 Email: yonggeun.hong@gmail.com Carles Gomez Universitat Politecnica de Catalunya/Fundacio i2cat C/Esteve Terradas, 7 08860 Castelldefels Spain Email: carlesgo@entel.upc.edu Younghwan Choi ETRI 218 Gajeongno, Yuseong Daejeon Phone: +82 42 860 1429 Email: yhc@etri.re.kr Hong, et al. Expires 29 July 2022 [Page 28] Internet-Draft 6lo Applicability & Use cases January 2022 Abdur Rashid Sangi Huaiyin Institute of Technology No.89 North Beijing Road, Qinghe District Huaian 223001 P.R. China Email: sangi_bahrian@yahoo.com Samita Chakrabarti San Jose, CA, United States of America Email: samitac.ietf@gmail.com Hong, et al. Expires 29 July 2022 [Page 29]