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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: '01 000000' is mentioned on line 101, but not defined == Unused Reference: 'RFC5226' is defined on line 311, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. '4944-ERRATA' -- Obsolete informational reference (is this intentional?): RFC 5226 (Obsoleted by RFC 8126) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6lo S. Chakrabarti 3 Internet-Draft Ericsson 4 Updates: 4944, 6282 (if approved) G. Montenegro 5 Intended status: Standards Track Microsoft 6 Expires: October 9, 2016 R. Droms 7 Cisco 8 J. Woodyatt 9 Nest 10 April 7, 2016 12 IANA Registry for 6lowpan ESC Dispatch Code points 13 draft-ietf-6lo-dispatch-iana-registry-03 15 Abstract 17 RFC4944 defines ESC dispatch type for additional dispatch bytes in 18 the 6lowpan header. The value of ESC byte has been updated by 19 RFC6282. However, the usage of ESC extension byte has not been 20 defined in RFC6282 and RFC4944. The purpose of this document is to 21 define the ESC extension byte code points and to request 22 corresponding IANA actions. 24 Status of this Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on October 9, 2016. 41 Copyright Notice 43 Copyright (c) 2016 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 3. Usage of ESC dispatch bytes . . . . . . . . . . . . . . . . . . 3 61 3.1. Interaction with other RFC4944 implementations . . . . . . 4 62 3.2. ESC Extension Bytes Typical Sequence . . . . . . . . . . . 5 63 3.3. ITU-T G.9903 ESC type usage . . . . . . . . . . . . . . . 5 64 3.4. NALP and ESC bytes . . . . . . . . . . . . . . . . . . . . 6 65 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 66 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 67 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 68 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 69 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 70 7.2. Informative References . . . . . . . . . . . . . . . . . . 8 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 73 1. Introduction 75 [RFC4944] section 5.1 defines the dispatch header and types. The ESC 76 type is defined for using additional dispatch bytes in the 6lowpan 77 header. RFC 6282 modifies the value of the ESC dispatch type and it 78 is recorded in IANA registry [6LOWPAN-IANA]. However, the bytes and 79 usage following the ESC byte are not defined in either [RFC4944] and 80 [RFC6282]. However, in recent years with 6lowpan deployments, the 81 implementations and Standards organizations have started using the 82 ESC extension bytes and a co-ordination between the respective 83 organizations and IETF/IANA are needed. 85 The following sections record the ITU-T specification for ESC 86 dispatch byte code points as an existing known usage and propose the 87 definition of ESC extension bytes for future applications. The 88 document also requests IANA actions for the first extension byte 89 following the ESC byte. 91 2. Terminology 93 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 94 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 95 document are to be interpreted as described in [RFC2119]. 97 3. Usage of ESC dispatch bytes 99 RFC 4944 [RFC4944] first introduces this "ESC" dispatch header type 100 for extension of dispatch bytes. RFC 6282 [RFC6282] subsequently 101 modified its value to [01 000000]. 103 This document specifies that the first octet following the ESC byte 104 be used for extension type (extended dispatch values). Subsequent 105 octets are left unstructured for the specific use of the extension 106 type: 108 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 1 109 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 110 |0 1| ESC | ESC EXT Type | Extended Dispatch Payload 111 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 113 Figure 1: Frame Format with ESC Byte 115 ESC: The left-most byte is the ESC dispatch type containing '0100000' 116 ESC Extension Type (EET): It is the first byte following the ESC 117 byte. Extension type defines the payload for the additional dispatch 118 bytes. The values are from 0 to 255. Value 0 and 255 are reserved 119 for future use. These values are assigned by IANA. The EET values 120 are similar to dispatch values in the 6lowpan header except they are 121 preceded by the ESC byte. Thus, ESC extension types and dispatch 122 values are using orthogonal code spaces. Though not desirable, 123 multiple ESC bytes MAY appear in a 6lowpan header. Section 3.1 124 describes how to handle unknown ESC dispatch type. 126 Extended Dispatch Payload(EDP): This part of frame format must be 127 defined by the corresponding extension type. A specification is 128 required to define each usage of extension type and its corresponding 129 Extension Payload. For the sake of interoperability, specifications 130 of extension bytes MUST NOT redefine the existing ESC Extension Type 131 codes. 133 Section 5.1 in RFC4944 indicates that the Extension Type field may 134 contain additional dispatch values larger than 63, as corrected by 135 [4944-ERRATA]. For the sake of interoperability, the new dispatch 136 type (EET) MUST NOT modify the behavior of existing dispatch types 137 [RFC4944]. 139 3.1. Interaction with other RFC4944 implementations 141 It is expected that RFC4944 existing implementations are not capable 142 of processing ESC extension data bytes as defined in this document. 143 However, implementers have to assume that existing implementation 144 that attempt to process an EET unknown to them will simply drop the 145 packet or ignore the ESC dispatch bytes. 147 If an implementation following this document, during processing of 148 the received packet reaches the ESC byte for which it does not 149 understand the extension bytes (EET), it MUST drop that packet. 150 However, it is important to clarify that a router node SHOULD forward 151 a 6lowpan packet with the EET bytes as long as it does not attempt to 152 process any unknown ESC extension bytes. 154 Sequence Of dispatch bytes and ESC bytes: Multiple ESC extension 155 bytes may appear in a packet. The ESC bytes can appear as the first, 156 last or middle dispatch bytes. However, a packet will get dropped by 157 any node that does not understand the EET at the beginning of the 158 packet. The closer to the end of the packet are the EET's, the 159 higher chance there is that a legacy node will recognize and 160 successfully process some dispatch type [RFC4944] before the EET and 161 then ignore the EET instead of dropping the entire packet. 163 3.2. ESC Extension Bytes Typical Sequence 165 ESC Extension bytes sequence and order with respect to 6LoWPAN Mesh 166 header and LoWPAN_IPHC header are described below. When LOWPAN_IPHC 167 dispatch type is present, ESC bytes MUST appear before the 168 LOWPAN_IPHC dispatch type in order to maintain backward compatibility 169 with RFC6282 section 3.2. The following diagrams provide examples of 170 ESC extension byte usages: 172 A LoWPAN encapsulated IPv6 Header compressed packet: 174 +-------+------+--------+--------+-----------------+--------+ 175 | ESC | EET | EDP |Dispatch| LOWPAN_IPHC hdr | Payld | 176 +-------+------+--------+--------+-----------------+--------+ 178 A LoWPAN_IPHC Header, Mesh header and an ESC extension byte: 180 +-----+-----+-----+----+------+-------+---------------+------+ 181 |M typ| Mhdr| ESC | EET|EDP |Disptch|LOWPAN_IPHC hdr| Payld| 182 +-----+-----+-----+----+------+-------+---------------+------+ 184 A Mesh header with ESC bytes 185 +-------+-------+-----+-----+-------+ 186 | M Typ | M Hdr | ESC | EET |EDP | 187 +-------+-------+-----+-----+-------+ 189 With Fragment header 191 +-------+-------+--------+------+-----+-----+-------+ 192 | M Typ | M Hdr | F Typ | F hdr|ESC | EET | EDP | 193 +-------+-------+--------+------+-----+-----+-------+ 195 ESC byte as a LowPAN encapsulation 197 +--------+--------+--------+ 198 | ESC | EET | EDP | 199 +--------+--------+--------+ 201 Figure 2: A 6lowpan packet with ESC Bytes 203 3.3. ITU-T G.9903 ESC type usage 205 The ESC dispatch type is used in [G3-PLC] to provide native mesh 206 routing and bootstrapping functionalities. The ITU-T recommendation 207 defines command IDs in the [G3-PLC] section 9.4.2.3 which operates 208 like ESC Extension type field. The command ID values are 0x01 to 209 0x1F. 211 The frame format is defined as follows: 213 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 1 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 |0 1| ESC | Command ID | Command Payload 216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 Figure 3: G.9903 Frame Format with ESC Byte 220 3.4. NALP and ESC bytes 222 According to RFC4944 [RFC4944] section 5.1, NALP dispatch bytes are 223 reserved for use as a kind of escape code for identification of non- 224 6lowpan payloads. Since ESC bytes are part of 6lowpan dispatch types 225 (extended), they are orthogonal to NALP bytes. 227 This document clarifies that NALP dispatch codes only provide an 228 escape method for non-6LoWPAN payloads when they appear as the 229 initial byte of a LoWPAN encapsulation, and that the potential 230 meaning of their appearance in any other location is reserved for 231 future use. 233 4. IANA Considerations 235 This document requests IANA to register the 'ESC Extension Type' 236 values as per the policy 'Specification Required'[RFC5226] as 237 specified in this document which follows the same policy as in the 238 IANA section of [RFC4944]. For each Extension Type (except the 239 Reserved values) the specification MUST define corresponding Extended 240 Dispatch Payload frame bytes for the receiver implementation to read 241 the ESC bytes with interoperability. 243 The initial values for the 'ESC Extension Type' fields are: 245 +-------+---------------------------------+---------------+ 246 | Value | Description | Reference | 247 +-------+---------------------------------+---------------+ 248 | 0 | Reserved for future use | This document | 249 | | | | 250 | 1-31 | Used by ITU-T G.9903 and G.9905 | ITU-T G.9903 &| 251 | | Command IDs | ITU-T G.9905 | 252 | | | | 253 | 32-254| Unassigned | This document | 254 | |(Reserved for future IANA | | 255 | | Assignment-- Spec Required) | | 256 | | | | 257 | 255 | Reserved for future use | This document | 258 +-------+---------------------------------+---------------+ 260 Figure 4: Initial Values for IANA Registry 262 5. Security Considerations 264 There is no additional security threats due to the assignments of ESC 265 byte usage described in this document. However, this document 266 forbids defining any extended dispatch values or extension types that 267 modifies the behavior of existing Dispatch types. 269 6. Acknowledgements 271 The authors would like to thank the members of the 6lo WG members for 272 the comments in the mailing list. Many thanks to Carsten Bormann, 273 Ralph Droms, Thierry Lys, Cedric Lavenu, Pascal Thubert for their 274 discussions regarding resolving the bits allocation issues which led 275 to this document. Jonathan Hui and Robert Cregie provided extensive 276 reviews and guidance for interoperability. The authors acknowledges 277 the comments from the following people for shaping this document: 278 Paul Duffy, Don Sturek, Michael Richardson, Xavier Vilajosana and 279 Scott Mansfield. 281 7. References 283 7.1. Normative References 285 [4944-ERRATA] 286 "https://www.rfc-editor.org/errata_search.php?rfc=4944". 288 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 289 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 290 RFC2119, March 1997, 291 . 293 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 294 "Transmission of IPv6 Packets over IEEE 802.15.4 295 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 296 . 298 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 299 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 300 DOI 10.17487/RFC6282, September 2011, 301 . 303 7.2. Informative References 305 [6LOWPAN-IANA] 306 "https://www.iana.org/assignments/_6lowpan-parameters/ 307 _6lowpan-parameters.xhtml". 309 [G3-PLC] "http://www.itu.int/rec/T-REC-G.9903-201402-I". 311 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 312 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 313 DOI 10.17487/RFC5226, May 2008, 314 . 316 Authors' Addresses 318 Samita Chakrabarti 319 Ericsson 320 300 Holger Way 321 San Jose, CA 322 US 324 Email: samita.chakrabarti@ericsson.com 326 Gabriel Montenegro 327 Microsoft 328 Seattle 329 US 331 Email: gabriel.montenegro@microsoft.com 332 Ralph Droms 333 Cisco 334 USA 336 Email: rdroms@cisco.com 338 James Woodyatt 339 Nest 340 Mountain View, CA 341 USA 343 Email: jhw@netstlabs.com