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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'I-D.ietf-6tisch-architecture' is defined on line 221, but no explicit reference was found in the text == Outdated reference: A later version (-30) exists of draft-ietf-6tisch-architecture-11 ** Obsolete normative reference: RFC 2461 (Obsoleted by RFC 4861) == Outdated reference: A later version (-15) exists of draft-ietf-6tisch-minimal-security-01 Summary: 2 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6lo Working Group D. Dujovne 3 Internet-Draft Universidad Diego Portales 4 Intended status: Informational M. Richardson 5 Expires: September 12, 2017 Sandelman Software Works 6 March 11, 2017 8 IEEE802.15.4 Informational Element encapsulation of 6tisch Join 9 Information 10 draft-richardson-6tisch-join-enhanced-beacon-01 12 Abstract 14 In TSCH mode of IEEE802.15.4, as described by 15 [I-D.ietf-6tisch-minimal], opportunities for broadcasts are limited 16 to specific times and specific channels. Nodes in a TSCH network 17 typically frequently send Enhanced Beacon (EB) frames to announce the 18 presence of the network. This document provides a mechanism by which 19 small details critical for new nodes (pledges) and long sleeping 20 nodes may be carried within the Enhanced Beacon. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on September 12, 2017. 39 Copyright Notice 41 Copyright (c) 2017 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 58 1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 3 59 1.3. Layer-3 synchronization IPv6 Router solicitations and 60 advertisements . . . . . . . . . . . . . . . . . . . . . 3 61 2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 4 62 2.1. Protocol Example . . . . . . . . . . . . . . . . . . . . 4 63 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 64 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5 65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 66 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 69 7.2. Informative References . . . . . . . . . . . . . . . . . 6 70 Appendix A. Change history . . . . . . . . . . . . . . . . . . . 6 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 73 1. Introduction 75 [RFC7554] describes the use of the time-slotted channel hopping 76 (TSCH) mode of [ieee802154]. As further details in 77 [I-D.ietf-6tisch-minimal], an Enhanced Beacon is transmitted during a 78 slot designated a broadcast slot. 80 EDNOTE: Explain why broadcasts are rare, and why we need them. What 81 the Enhanced Beacon is, and what Information Elements are, and how 82 the IETF has a subtype for that area. Explain what kind of things 83 could be placed in Information Elements, how big they could be, and 84 how they could be compressed. 86 1.1. Terminology 88 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 89 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 90 and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 91 [RFC2119] and indicate requirement levels for compliant STuPiD 92 implementations. 94 1.2. Layer-2 Synchronization 96 As explained in section 6 of [I-D.ietf-6tisch-minimal], the Enhanced 97 Beacon has a number of purposes: synchronization of ASN and Join 98 Metric, timeslot template identifier, the channel hopping sequence 99 identifier, TSCH SlotFrame and Link IE. 101 The Enhanced Beacon (EB) is used by nodes already part of a TSCH 102 network to annouce its existance. Receiving an EB allows a Joining 103 Node (pledge) to learn about the network and synchronize to it. The 104 EB may also be used as a means for a node already part of the network 105 to re-synchronize [RFC7554]. 107 There are a limited number of timeslots designated as a broadcast 108 slot by each router. These slots are rare, and with 10ms slots, with 109 a slot-frame length of 100, there may be only 1 slot/s for the 110 beacon. 112 1.3. Layer-3 synchronization IPv6 Router solicitations and 113 advertisements 115 At layer 3, [RFC2461] defines a mechanism by which nodes learn about 116 routers by listening for multicasted Router Advertisements (RA). If 117 no RA is heard within a set time, then a Router Solicitation (RS) may 118 be multicast, to which an RA will be received, usually unicast. 120 Although [RFC6775] reduces the amount of multicast necessary to do 121 address resolution via Neighbor Solicitation messages, it still 122 requires multicast of either RAs or RS. This is an expensive 123 operation for two reasons: there are few multicast timeslots for 124 unsolicited RAs; if a pledge node does not hear an RA, and decides to 125 send a RS (consuming a broadcast aloha slot with unencrypted 126 traffic), many unicast RS may be sent in response. 128 This is a particularly acute issue for the join process for the 129 following reasons: 131 1. use of a multicast slot by even a non-malicious unauthenticated 132 node for a Router Solicitation may overwhelm that time slot. 134 2. it may require many seconds of on-time before a new pledge hears 135 a Router Soliciation that it can use. 137 3. a new pledge may listen to many Enhanced Beacons before it can 138 pick an appropriate network and/or closest Join Assistant to 139 attach to. If it must listen for a RS as well as find the 140 Enhanced Beacon, then the process may take a very long time. 142 2. Protocol Definition 144 [I-D.kivinen-802-15-ie] creates a registry for new IETF IE subtypes. 145 This document allocates a new subtype TBD-XXX. 147 This document documents a new IE subtype structure is as follows. As 148 explained in [I-D.kivinen-802-15-ie] the length of the Sub-Type 149 Content can be calculated from the container, so no length 150 information is necessary. 152 1 2 3 153 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | TBD-XXX |J|I|R| R E S V | network ID | 156 +-+-+-+-+-+-+-+-+-+-+-+---------+ | 157 | network ID | 158 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | network ID | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 J the Join Proxy flag is set if the sending node will operate as a 163 Join Proxy according to [I-D.ietf-6tisch-minimal-security]. 165 I the Initiate Join flag is set if this network supports pledges 166 initiating the join process themselves according to 167 [I-D.ietf-6tisch-minimal-security]. If not set, then the pledge 168 should do an NS DAD operation ([RFC6775] section 4.3, explained in 169 [I-D.ietf-6tisch-dtsecurity-secure-join]) and then remain silent, 170 to wait to be contacted. 172 R the Router Advertisement flag is set if the sending node will act 173 as a Router for host-only nodes that need addressing via unicast 174 Router Solicitation messages. 176 network ID this is an opaque 16-byte identifier that uniquely 177 identifies this network, potentially among many networks that are 178 operating in the same frequencies in overlapping physical space. 180 In a 6tisch network, where RPL is used as the mesh routing protocol, 181 the network ID SHOULD be constructed from a SHA256 hash of the 182 DODAGID of the network. The result will be a 32-byte hash, and the 183 lower 16-bytes should be used. 185 2.1. Protocol Example 187 Here are three examples of processing. 189 3. Security Considerations 191 All of the contents of this Information Element are sent in the 192 clear. The containing Enhanced Beacon is not encrypted, but may be 193 authenticated to nodes which have already received network-wide 194 keying material. 196 4. Privacy Considerations 198 The use of a network ID may reveal information about the network. 199 The use of a SHA256 hash of the DODAGID, rather than using the 200 DODAGID directly provides some cover the addresses used within the 201 network. The DODAGID is usually the IPv6 address of the root of the 202 RPL mesh. 204 An interloper with a radio sniffer would be able to use the network 205 ID to map out the extend of the mesh network. 207 5. IANA Considerations 209 Allocate a new number TBD-XXX from Registry IETF IE Sub-type ID. 210 This entry should be called 6tisch-Join-Info. 212 6. Acknowledgements 214 Thomas Watteyne provided extensive editorial comments on the 215 document. 217 7. References 219 7.1. Normative References 221 [I-D.ietf-6tisch-architecture] 222 Thubert, P., "An Architecture for IPv6 over the TSCH mode 223 of IEEE 802.15.4", draft-ietf-6tisch-architecture-11 (work 224 in progress), January 2017. 226 [I-D.ietf-6tisch-minimal] 227 Vilajosana, X., Pister, K., and T. Watteyne, "Minimal 228 6TiSCH Configuration", draft-ietf-6tisch-minimal-21 (work 229 in progress), February 2017. 231 [I-D.kivinen-802-15-ie] 232 Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information 233 Element for IETF", draft-kivinen-802-15-ie-06 (work in 234 progress), March 2017. 236 [ieee802154] 237 IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low- 238 Rate Wireless Personal Area Networks (WPANs)", 2015, 239 . 242 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 243 Requirement Levels", BCP 14, RFC 2119, 244 DOI 10.17487/RFC2119, March 1997, 245 . 247 [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor 248 Discovery for IP Version 6 (IPv6)", RFC 2461, 249 DOI 10.17487/RFC2461, December 1998, 250 . 252 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 253 Bormann, "Neighbor Discovery Optimization for IPv6 over 254 Low-Power Wireless Personal Area Networks (6LoWPANs)", 255 RFC 6775, DOI 10.17487/RFC6775, November 2012, 256 . 258 [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using 259 IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the 260 Internet of Things (IoT): Problem Statement", RFC 7554, 261 DOI 10.17487/RFC7554, May 2015, 262 . 264 7.2. Informative References 266 [I-D.ietf-6tisch-dtsecurity-secure-join] 267 Richardson, M., "6tisch Secure Join protocol", draft-ietf- 268 6tisch-dtsecurity-secure-join-01 (work in progress), 269 February 2017. 271 [I-D.ietf-6tisch-minimal-security] 272 Vucinic, M., Simon, J., and K. Pister, "Minimal Security 273 Framework for 6TiSCH", draft-ietf-6tisch-minimal- 274 security-01 (work in progress), February 2017. 276 Appendix A. Change history 278 This is an evolution of an earlier proposal which provided for 279 storing an entire IPv6 Router Adverisement in an Informational 280 Element. It was deemed too general a solution, possibly subject to 281 mis-use. This proposal restricts the use to just the key pieces of 282 information required. 284 Authors' Addresses 286 Diego Dujovne (editor) 287 Universidad Diego Portales 288 Escuela de Informatica y Telecomunicaciones, Av. Ejercito 441 289 Santiago, Region Metropolitana 290 Chile 292 Phone: +56 (2) 676-8121 293 Email: diego.dujovne@mail.udp.cl 295 Michael Richardson 296 Sandelman Software Works 298 Email: mcr+ietf@sandelman.ca