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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-30) exists of draft-ietf-6tisch-architecture-11 == Outdated reference: A later version (-21) exists of draft-ietf-6tisch-minimal-19 == Outdated reference: A later version (-06) exists of draft-kivinen-802-15-ie-04 ** Obsolete normative reference: RFC 2461 (Obsoleted by RFC 4861) == Outdated reference: A later version (-01) exists of draft-ietf-6tisch-dtsecurity-secure-join-00 == Outdated reference: A later version (-15) exists of draft-ietf-6tisch-minimal-security-01 Summary: 2 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6lo Working Group M. Richardson 3 Internet-Draft Sandelman Software Works 4 Intended status: Informational February 08, 2017 5 Expires: August 12, 2017 7 802.15.4 Informational Element encapsulation of 6tisch Join Information 8 draft-richardson-6tisch-join-enhanced-beacon-00 10 Abstract 12 In TSCH mode of 802.15.4, as described by [I-D.ietf-6tisch-minimal], 13 opportunities for broadcasts are limited to specific times and 14 specific channels. An enhanced beacon must be broadcast periodically 15 by every router to keep all nodes in sync. This document provides a 16 mechanism by which small details critical for new nodes (pledges) and 17 long sleeping nodes may be carried within the Enhanced Beacon. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on August 12, 2017. 36 Copyright Notice 38 Copyright (c) 2017 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 2 56 1.3. Layer-3 synchronization IPv6 Router solicitations and 57 advertisements . . . . . . . . . . . . . . . . . . . . . 3 58 2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 3 59 2.1. Protocol Example . . . . . . . . . . . . . . . . . . . . 4 60 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 61 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5 62 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 65 6.2. Informative References . . . . . . . . . . . . . . . . . 6 66 Appendix A. Change history . . . . . . . . . . . . . . . . . . . 6 67 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 69 1. Introduction 71 [I-D.ietf-6tisch-architecture] describes the use of the time-slotted 72 channel hopping (TSCH) mode of [ieee802154]. As further details in 73 [I-D.ietf-6tisch-minimal], an Enhanced Beacon is transmitted during a 74 slot designated a broadcast slot. 76 EDNOTE: Explain why broadcasts are rare, and why we need them. What 77 the Enhanced Beacon is, and what Information Elements are, and how 78 the IETF has a subtype for that area. Explain what kind of things 79 could be placed in Information Elements, how big they could be, and 80 how they could be compressed. 82 1.1. Terminology 84 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 85 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 86 and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 87 [RFC2119] and indicate requirement levels for compliant STuPiD 88 implementations. 90 1.2. Layer-2 Synchronization 92 As explained in section 6 of [I-D.ietf-6tisch-minimal], the Enhanced 93 Beacon has a number of purposes: synchronization of ASN and Join 94 Metric, timeslot template identifier, the channel hopping sequence 95 identifier, TSCH SlotFrame and Link IE. 97 The Enhanced Beacon is used by operating nodes to correct drift in 98 their clock, by nodes on medium length sleeps to resynchronize their 99 ASN, by nodes that have slept through a network rekey to rediscover 100 the network, and by new Joining Nodes (pledges) to learn about the 101 existance of the network. 103 There are a limited number of timeslots designated as a broadcast 104 slot by each router. These slots are rare, and with 10ms slots, with 105 a slot-frame length of 100, there may be only 1 slot/s for the 106 beacon. 108 1.3. Layer-3 synchronization IPv6 Router solicitations and 109 advertisements 111 At layer 3, [RFC2461] defines a mechanism by which nodes learn about 112 routers by listening for multicasted Router Advertisements (RA). If 113 no RA is heard within a set time, then a Router Solicitation (RS) may 114 be multicast, to which an RA will be received, usually unicast. 116 Although [RFC6775] reduces the amount of multicast necessary to do 117 address resolution via Neighbor Solicitation messages, it still 118 requires multicast of either RAs or RS. This is an expensive 119 operation for two reasons: there are few multicast timeslots for 120 unsolicited RAs; if a pledge node does not hear an RA, and decides to 121 send a RS (consuming a broadcast aloha slot with unencrypted 122 traffic), many unicast RS may be sent in response. 124 This is a particularly acute issue for the join process for the 125 following reasons: 127 1. use of a multicast slot by even a non-malicious unauthenticated 128 node for a Router Solicitation may overwhelm that time slot. 130 2. it may require many seconds of on-time before a new pledge hears 131 a Router Soliciation that it can use. 133 3. a new pledge may listen to many Enhanced Beacons before it can 134 pick an appropriate network and/or closest Join Assistant to 135 attach to. If it must listen for a RS as well as find the 136 Enhanced Beacon, then the process may take a very long time. 138 2. Protocol Definition 140 [I-D.kivinen-802-15-ie] creates a registry for new IETF IE subtypes. 141 This document allocates a new subtype TBD-XXX. 143 This document documents a new IE subtype structure is as follows. As 144 explained in [I-D.kivinen-802-15-ie] the length of the Sub-Type 145 Content can be calculated from the container, so no length 146 information is necessary. 148 1 2 3 149 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 1 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | TBD-XXX |J|I|R| R E S V | network ID | 152 +-+-+-+-+-+-+-+-+-+-+-+---------+ | 153 | network ID | 154 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | network ID | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 J the Join Proxy flag is set if the sending node will operate as a 159 Join Proxy according to [I-D.ietf-6tisch-minimal-security]. 161 I the Initiate Join flag is set if this network supports pledges 162 initiating the join process themselves according to 163 [I-D.ietf-6tisch-minimal-security]. If not set, then the pledge 164 should do an NS DAD operation ([RFC6775] section 4.3, explained in 165 [I-D.ietf-6tisch-dtsecurity-secure-join]) and then remain silent, 166 to wait to be contacted. 168 R the Router Advertisement flag is set if the sending node will act 169 as a Router for host-only nodes that need addressing via unicast 170 Router Solicitation messages. 172 network ID this is an opaque 16-byte identifier that uniquely 173 identifies this network, potentially among many networks that are 174 operating in the same frequencies in overlapping physical space. 176 In a 6tisch network, where RPL is used as the mesh routing protocol, 177 the network ID SHOULD be constructed from a SHA256 hash of the 178 DODAGID of the network. The result will be a 32-byte hash, and the 179 lower 16-bytes should be used. 181 2.1. Protocol Example 183 Here are three examples of processing. 185 3. Security Considerations 187 All of the contents of this Information Element are sent in the 188 clear. The containing Enhanced Beacon is not encrypted, but may be 189 authenticated to nodes which have already received network-wide 190 keying material. 192 4. Privacy Considerations 194 The use of a network ID may reveal information about the network. 195 The use of a SHA256 hash of the DODAGID, rather than using the 196 DODAGID directly provides some cover the addresses used within the 197 network. The DODAGID is usually the IPv6 address of the root of the 198 RPL mesh. 200 5. IANA Considerations 202 Allocate a new number TBD-XXX from Registry IETF IE Sub-type ID. 203 This entry should be called 6LoRH-in-IE. 205 Allocate a new number TBD-YYY from Neighbor Discovery Option Types 206 (RFC2461) with the name "Constrained Network Identification". 208 6. References 210 6.1. Normative References 212 [I-D.ietf-6tisch-architecture] 213 Thubert, P., "An Architecture for IPv6 over the TSCH mode 214 of IEEE 802.15.4", draft-ietf-6tisch-architecture-11 (work 215 in progress), January 2017. 217 [I-D.ietf-6tisch-minimal] 218 Vilajosana, X., Pister, K., and T. Watteyne, "Minimal 219 6TiSCH Configuration", draft-ietf-6tisch-minimal-19 (work 220 in progress), January 2017. 222 [I-D.kivinen-802-15-ie] 223 Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information 224 Element for IETF", draft-kivinen-802-15-ie-04 (work in 225 progress), October 2016. 227 [ieee802154] 228 IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low- 229 Rate Wireless Personal Area Networks (WPANs)", 2015, 230 . 233 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 234 Requirement Levels", BCP 14, RFC 2119, 235 DOI 10.17487/RFC2119, March 1997, 236 . 238 [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor 239 Discovery for IP Version 6 (IPv6)", RFC 2461, 240 DOI 10.17487/RFC2461, December 1998, 241 . 243 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 244 Bormann, "Neighbor Discovery Optimization for IPv6 over 245 Low-Power Wireless Personal Area Networks (6LoWPANs)", 246 RFC 6775, DOI 10.17487/RFC6775, November 2012, 247 . 249 6.2. Informative References 251 [I-D.ietf-6tisch-dtsecurity-secure-join] 252 Richardson, M., "6tisch Secure Join protocol", draft-ietf- 253 6tisch-dtsecurity-secure-join-00 (work in progress), 254 December 2016. 256 [I-D.ietf-6tisch-minimal-security] 257 Vucinic, M., Simon, J., and K. Pister, "Minimal Security 258 Framework for 6TiSCH", draft-ietf-6tisch-minimal- 259 security-01 (work in progress), February 2017. 261 Appendix A. Change history 263 This is an evolution of an earlier proposal which provided for 264 storing an entire IPv6 Router Adverisement in an Informational 265 Element. It was deemed too general a solution, possibly subject to 266 mis-use. This proposal restricts the use to just the key pieces of 267 information required. 269 Author's Address 271 Michael Richardson 272 Sandelman Software Works 274 Email: mcr+ietf@sandelman.ca