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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 TODO Working Group C. Gündoğan 3 Internet-Draft HAW Hamburg 4 Intended status: Informational C. Amsüss 5 Expires: 26 August 2021 6 TC. Schmidt 7 HAW Hamburg 8 M. Waehlisch 9 link-lab & FU Berlin 10 22 February 2021 12 A Data-centric Deployment Option for CoAP 13 draft-gundogan-core-icncoap-00 15 Abstract 17 The information-centric networking (ICN) paradigm offers replication 18 of autonomously verifiable content throughout a network, in which 19 content is bound to names instead of hosts. This has proven 20 beneficial in particular for the constrained IoT. Several 21 approaches, the most prominent of which being Content-Centric 22 Networking (CCNx) and Named-Data Networking (NDN), propose access to 23 named content directly on the network layer. Independently, the CoRe 24 WG developed mechanisms that support autonomous content processing, 25 on-path caching, and content object security using CoAP proxies and 26 OSCORE. 28 This document describes a data-centric deployment option using 29 standard CoAP features to replicate information-centric properties 30 and benefits to the host-centric IoT world. 32 Discussion Venues 34 This note is to be removed before publishing as an RFC. 36 Discussion of this document takes place on the Constrained RESTful 37 Environments Working Group mailing list (core@ietf.org), which is 38 archived at https://mailarchive.ietf.org/arch/browse/core/. 40 Source for this draft and an issue tracker can be found at 41 https://github.com/inetrg/draft-core-icncoap. 43 Status of This Memo 45 This Internet-Draft is submitted in full conformance with the 46 provisions of BCP 78 and BCP 79. 48 Internet-Drafts are working documents of the Internet Engineering 49 Task Force (IETF). Note that other groups may also distribute 50 working documents as Internet-Drafts. The list of current Internet- 51 Drafts is at https://datatracker.ietf.org/drafts/current/. 53 Internet-Drafts are draft documents valid for a maximum of six months 54 and may be updated, replaced, or obsoleted by other documents at any 55 time. It is inappropriate to use Internet-Drafts as reference 56 material or to cite them other than as "work in progress." 58 This Internet-Draft will expire on 26 August 2021. 60 Copyright Notice 62 Copyright (c) 2021 IETF Trust and the persons identified as the 63 document authors. All rights reserved. 65 This document is subject to BCP 78 and the IETF Trust's Legal 66 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 67 license-info) in effect on the date of publication of this document. 68 Please review these documents carefully, as they describe your rights 69 and restrictions with respect to this document. Code Components 70 extracted from this document must include Simplified BSD License text 71 as described in Section 4.e of the Trust Legal Provisions and are 72 provided without warranty as described in the Simplified BSD License. 74 Table of Contents 76 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 77 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 78 3. Data-centric Deployment Option for CoAP . . . . . . . . . . . 3 79 3.1. Stateful Forwarding . . . . . . . . . . . . . . . . . . . 3 80 3.2. Content Caching . . . . . . . . . . . . . . . . . . . . . 4 81 3.3. Corrective Actions . . . . . . . . . . . . . . . . . . . 4 82 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 83 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 84 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 85 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 86 6.2. Informative References . . . . . . . . . . . . . . . . . 6 87 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 90 1. Introduction 92 Information-Centric Networking (ICN) introduced the idea to turn 93 named content objects into first class citizens of the Internet 94 ecosystem. This paradigm gave rise to (i) a decoupling of content 95 from hosts and the ability of ubiquitous content caching without 96 content delivery networks (CDNs), and (ii) serverless routing on 97 names without the DNS infrastructure; (iii) Named Data Networking 98 (NDN) additionally abandoned network endpoint addresses in favor of a 99 stateful forwarding fabric. These properties enable an asynchronous, 100 hop-wise content fetching, which prevents forwarding of unsolicited 101 data. The latter significantly reduces the attack surface of 102 (Distributed) Denial-of-Service (DDoS). 104 All three constituents make ICN appealing to the (constrained) 105 Internet of Things (IoT) as infrastructural burdens and common DDoS 106 threats stand in the way of a lean and efficient inter-networking for 107 embedded devices. Early experimental work [NDN-IOT] shows that NDN 108 can successfully operate on very constrained nodes with noticeable 109 resource savings compared to IP. In addition, short-term in-network 110 caching proved valuable for increasing reliability in low-power lossy 111 networks with nodes frequently at sleep as common at the IoT edge. 113 The deployment option described in this document replicates these 114 information-centric properties using standard CoAP features. Recent 115 experimental evaluations [OBJECTSEC][ICN-COAP] in a testbed with real 116 IoT hardware demonstrate promising results. 118 2. Requirements Language 120 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 121 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 122 "OPTIONAL" in this document are to be interpreted as described in BCP 123 14 [RFC2119] [RFC8174] when, and only when, they appear in all 124 capitals, as shown here. 126 3. Data-centric Deployment Option for CoAP 128 3.1. Stateful Forwarding 130 In the data-centric deployment, all IoT devices act as CoAP proxies 131 with enabled caching functionality. A forwarding information base 132 (FIB) on the application-layer describes a mapping of resource names 133 to next-hop CoAP proxies. This mapping list is compiled statically, 134 or is dynamically discovered in the network; future document 135 iterations will further elaborate on this topic. 137 Within the IoT stub network, requests traverse multiple proxies, 138 install forwarding state, and build return paths for corresponding 139 responses. The use of IPv6 link-local addresses between each proxy 140 hop is encouraged for a better 6LoWPAN compressibility. Responses 141 return on symmetrical request paths, which consequently consumes 142 existing forwarding state. 144 3.2. Content Caching 146 A deployment of proxy nodes on each hop enables a hop-wise caching 147 just as performed by CCNx [RFC8569] and NDN. Responses replicate on 148 a request path following a cache decision and cache replacement 149 strategy. A simple and lightweight approach is to _cache everywhere_ 150 and replace _least recently used_ (LRU) content. 152 OSCORE enables content object security for CoAP and allows for 153 transmitting autonomously verifiable content similar to CCNx and NDN. 154 Further details on cachable OSCORE messages is recorded in 155 [I-D.draft-amsuess-core-cachable-oscore-00]. 157 3.3. Corrective Actions 159 In contrast to end-to-end retransmissions for standard CoAP 160 deployments, the data-centric setup performs hop-wise retransmissions 161 in the event of message timeouts. Confirmable messages arm message 162 timers on each proxy node. 164 Figure 1 illustrates the default retransmission behavior: each 165 subsequent packet traverses the full request path to recover a lost 166 message. 168 Initial request: 170 ,-------, Request ,-------, Request ,-------, 171 |client |------------|router |----------->|server | 172 | | x---------| |------------| | 173 '-------' Response '-------' Response '-------' 175 Request retransmission: 177 ,-------, Request ,-------, Request ,-------, 178 |client |------------|router |----------->|server | 179 | |<-----------| |------------| | 180 '-------' Response '-------' Response '-------' 182 Figure 1: End-to-end recovery of lost packets. 184 Figure 2 demonstrates the shortening of request paths for subsequent 185 request retransmissions due to the on-path caching functionality. 187 Initial request: 189 ,-------, Request ,-------, Request ,-------, 190 | Proxy |----------->| Proxy |----------->| Proxy | 191 |(cache)| x---------|(cache)|<-----------|(cache)| 192 '-------' Response '-------' Response '-------' 194 Request retransmission: 196 ,-------, Request ,-------, ,-------, 197 | Proxy |----------->| Proxy | | Proxy | 198 |(cache)|<-----------|(cache)| |(cache)| 199 '-------' Response '-------' '-------' 201 Figure 2: Hop-wise recovery of lost packets with on-path caching. 203 Proxy nodes aggregate requests and suppress the forwarding procedure, 204 if they already maintain an on-going request with the same cache key. 206 4. Security Considerations 208 TODO Security 210 5. IANA Considerations 212 This document has no IANA actions. 214 6. References 216 6.1. Normative References 218 [I-D.draft-amsuess-core-cachable-oscore-00] 219 Amsuess, C. and M. Tiloca, "Cachable OSCORE", Work in 220 Progress, Internet-Draft, draft-amsuess-core-cachable- 221 oscore-00, 13 July 2020, . 224 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 225 Requirement Levels", BCP 14, RFC 2119, 226 DOI 10.17487/RFC2119, March 1997, 227 . 229 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 230 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 231 May 2017, . 233 6.2. Informative References 235 [ICN-COAP] Gündoğan, C., Amsüss, C., Schmidt, TC., and M. Waehlisch, 236 "Toward a RESTful Information-Centric Web of Things: A 237 Deeper Look at Data Orientation in CoAP", Proceedings 238 of 7th ACM ICN, DOI 10.1145/3405656.3418718, 2020, 239 . 241 [NDN-IOT] Gündoğan, C., Kietzmann, P., Lenders, M., Petersen, H., 242 Schmidt, TC., and M. Waehlisch, "NDN, CoAP, and MQTT: a 243 comparative measurement study in the IoT", Proceedings 244 of 5th ACM ICN, DOI 10.1145/3267955.3267967, 2018, 245 . 247 [OBJECTSEC] 248 Gündoğan, C., Amsüss, C., Schmidt, TC., and M. Waehlisch, 249 "IoT Content Object Security with OSCORE and NDN: A First 250 Experimental Comparison", Proceedings of 19th IFIP 251 Networking, 2020, 252 . 254 [RFC8569] Mosko, M., Solis, I., and C. Wood, "Content-Centric 255 Networking (CCNx) Semantics", RFC 8569, 256 DOI 10.17487/RFC8569, July 2019, 257 . 259 Acknowledgments 261 TODO acknowledge. 263 Authors' Addresses 265 Cenk Gündoğan 266 HAW Hamburg 268 Email: cenk.guendogan@haw-hamburg.de 270 Christian Amsüss 272 Email: christian@amsuess.com 273 Thomas C. Schmidt 274 HAW Hamburg 276 Email: t.schmidt@haw-hamburg.de 278 Matthias Waehlisch 279 link-lab & FU Berlin 281 Email: m.waehlisch@haw-hamburg.de