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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) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 4242 (Obsoleted by RFC 8415) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 roll Y. Doi 3 Internet-Draft TOSHIBA Corporation 4 Intended status: Standards Track M. Gillmore 5 Expires: March 5, 2016 Itron, Inc 6 September 2, 2015 8 MPL Parameter Configuration Option for DHCPv6 9 draft-ietf-roll-mpl-parameter-configuration-07 11 Abstract 13 This document defines a way to configure a parameter set for MPL 14 (Multicast Protocol for Low power and Lossy Networks) via a DHCPv6 15 option. MPL has a set of parameters to control its behavior, and the 16 parameter set is often configured as a network-wide parameter because 17 the parameter set should be identical for each MPL forwarder in an 18 MPL domain. Using the MPL Parameter Configuration Option defined in 19 this document, a network can easily be configured with a single set 20 of MPL parameters. 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 March 5, 2016. 39 Copyright Notice 41 Copyright (c) 2015 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 2. MPL Parameter Configuration Option . . . . . . . . . . . . . 3 58 2.1. MPL Parameter Configuration Option Format . . . . . . . . 3 59 2.2. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . 6 60 2.3. MPL Forwarder Behavior . . . . . . . . . . . . . . . . . 6 61 2.4. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . 7 62 2.5. DHCPv6 Relay Behavior . . . . . . . . . . . . . . . . . . 7 63 2.6. Operational Considerations . . . . . . . . . . . . . . . 7 64 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 65 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 66 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 5.1. Normative References . . . . . . . . . . . . . . . . . . 8 68 5.2. Informative References . . . . . . . . . . . . . . . . . 9 69 Appendix A. Considerations on Inconsistent Parameter Set . . . . 9 70 Appendix B. Update History (TO EDITORS: this section is intended 71 to be removed before this document becomes an RFC) . 10 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 74 1. Introduction 76 Multicast Protocol for Low power and Lossy Networks (MPL) 77 [I-D.ietf-roll-trickle-mcast] defines a protocol to make a multicast 78 network among low-power and lossy networks, e.g., wireless mesh 79 networks. MPL has a set of parameters to control an MPL domain. The 80 parameters control the trade-off between end-to-end delay and network 81 utilization. In most environments, the default parameters are 82 acceptable. However, in some environments, the parameter set must be 83 configured carefully in order to meet the requirements of each 84 environment. According to the MPL document section 5.4, each 85 parameter in the set should be the same for all nodes within an MPL 86 domain, but the MPL document does not define a method to configure 87 the MPL parameter set. 89 Some managed wireless mesh networks may have a DHCP server to 90 configure network parameters. MPL parameter sets shall be considered 91 as a part of network parameters (nodes in an MPL domain should use an 92 identical parameter set). And a parameter set is required to 93 configure an MPL domain. 95 This document defines the way to distribute parameter sets for MPL 96 forwarders as a DHCPv6 [RFC3315] option. This document is intended 97 to follow [RFC7227] the guideline. 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 101 document are to be interpreted as described in [RFC2119]. 103 2. MPL Parameter Configuration Option 105 As stated in Section 5.4 of [I-D.ietf-roll-trickle-mcast], there are 106 the following 10 parameters per MPL domain. An MPL domain is defined 107 by an MPL domain address, as described in Section 2 of 108 [I-D.ietf-roll-trickle-mcast]. 110 o PROACTIVE_FORWARDING 112 o SEED_SET_ENTRY_LIFETIME 114 o DATA_MESSAGE_IMIN 116 o DATA_MESSAGE_IMAX 118 o DATA_MESSAGE_K 120 o DATA_MESSAGE_TIMER_EXPIRATIONS 122 o CONTROL_MESSAGE_IMIN 124 o CONTROL_MESSAGE_IMAX 126 o CONTROL_MESSAGE_K 128 o CONTROL_MESSAGE_TIMER_EXPIRATIONS 130 One network may have multiple MPL domains with different 131 configurations. To configure more than one MPL domain via DHCP, 132 there may be more than one MPL Parameter Configuration Option given 133 to DHCP clients by a DHCP server. 135 2.1. MPL Parameter Configuration Option Format 137 To distribute a configuration of an MPL domain or a default value for 138 all MPL domains (wildcard) under the network managed by the DHCP 139 server, this document defines a DHCPv6 option format as follows. 141 0 1 2 3 142 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 1 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | OPTION_MPL_PARAMETERS | option_len | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 |P| Z | TUNIT | SE_LIFETIME | 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | DM_K | DM_IMIN | DM_IMAX | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | DM_T_EXP | C_K | C_IMIN > 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 153 >(cont'ed) | C_IMAX | C_T_EXP | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 (if option_len = 32 ) 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | MPL Domain Address (128bits) > 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 > (cont'ed) > 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 > (cont'ed) > 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 > (cont'ed) | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 OPTION_MPL_PARAMETERS: DHCPv6 option identifier (not yet assigned). 169 option_len: Length of the option. It SHOULD be 16 (without MPL 170 domain address) or 32 (with MPL domain address). 172 P (1 bit): A flag to indicate PROACTIVE_FORWARDING. The flag is set 173 if PROACTIVE_FORWARDING is true. 175 Z (7 bits): Reserved for future use. Servers MUST set them to zero. 176 Clients SHOULD ignore the bits set. 178 TUNIT (unsigned 8-bit integer): Unit time of timer parameters 179 (SE_LIFETIME, and *_IMIN) in this option. 0 and 0xff are reserved 180 and MUST NOT be used. 182 SE_LIFETIME (unsigned 16-bit integer): SEED_SET_ENTRY_LIFETIME/TUNIT 183 in milliseconds. 0 and 0xffff are reserved and MUST NOT be used. 185 DM_K (unsigned 8-bit integer): DATA_MESSAGE_K. 187 DM_IMIN (unsigned 16-bit integer): DATA_MESSAGE_IMIN/TUNIT in 188 milliseconds. 0 and 0xffff are reserved and MUST NOT be used. 190 DM_IMAX (unsigned 8-bit integer): DATA_MESSAGE_IMAX. The actual 191 maximum timeout is described as a number of doublings of 192 DATA_MESSAGE_IMIN, as described in [RFC6206] Section 4.1. 0 and 193 0xff are reserved and MUST NOT be used. 195 DM_T_EXP (unsigned 16-bit integer): DATA_MESSAGE_TIMER_EXPIRATIONS. 196 0 and 0xffff are reserved and MUST NOT be used. 198 C_K (unsigned 8-bit integer): CONTROL_MESSAGE_K. 200 C_IMIN (unsigned 16-bit integer): CONTROL_MESSAGE_IMIN/TUNIT in 201 milliseconds. 0 and 0xffff are reserved and MUST NOT be used. 203 C_IMAX (unsigned 8-bit integer): CONTROL_MESSAGE_IMAX. The actual 204 maximum timeout is described as a number of doublings of 205 CONTROL_MESSAGE_IMIN. 0 and 0xff are reserved and MUST NOT be 206 used. 208 C_T_EXP (unsigned 16-bit integer): CONTROL_MESSAGE_TIMER_EXPIRATIONS 209 . 0 and 0xffff are reserved and MUST NOT be used. 211 Note that the time values (SEED_SET_ENTRY_LIFETIME, 212 DATA_MESSAGE_IMIN, and CONTROL_MESSAGE_IMIN) in MPL are defined in 213 TUNIT milliseconds precision in MPL Parameter Configuration Options. 214 For example, if TUNIT is 20 and the data message interval minimum 215 (DATA_MESSAGE_IMIN) is 1000ms, then DM_IMIN shall be set to 50. 217 For maximum interval size (*_IMAX), [RFC6206] defines them as 218 follows: 220 The maximum interval size, Imax, is described as a number of 221 doublings of the minimum interval size (the base-2 log(max/min)). 222 For example, a protocol might define Imax as 16. If the minimum 223 interval is 100 ms, then the amount of time specified by Imax is 224 100 ms * 65,536, i.e., 6,553.6 seconds or approximately 109 225 minutes. 227 Because minimum interval size in the MPL Parameter Configuration 228 Options is described as TUNIT millisecond precision, corresponding 229 maximum interval size is also in TUNIT precision. For example, if 230 TUNIT is 10 and C_IMIN is 50, the minimum interval size of the 231 trickle timer for control messages is 500ms. In this case, the 232 maximum interval size of the trickle timer is 32 seconds (500ms * 233 2^6) if C_IMAX is 6. 235 2.2. DHCPv6 Client Behavior 237 Clients MAY request the MPL Parameter Configuration Option, as 238 described in [RFC3315], sections 17.1.1, 18.1.1, 18.1.3, 18.1.4, 239 18.1.5, and 22.7. As a convenience to the reader, we mention here 240 that the client includes requested option codes in the Option Request 241 Option. 243 Clients MUST support multiple MPL Parameter Configuration Option, as 244 stated in section 2. 246 If a DHCPv6 client with an MPL forwarder configured by the MPL 247 Parameter Configuration Option is unable to receive a valid response 248 from a server within T2 of the last valid DHCPv6 message sent from 249 the server (if stateful) or twice the Information Refresh Time (if 250 stateless), it MUST suspend the MPL forwarders of the MPL domains 251 configured by the option. MPL forwarders configured by other methods 252 such as static configuration file MUST NOT be suspended. 254 Clients MUST ignore all MPL Parameter Configuration Options if the 255 options in a DHCPv6 message contains any invalid value (e.g., it uses 256 reserved all-0 or all-1 values in parameters). In this case, the 257 message is considered not received in MPL context and the condition 258 described in the previous paragraph applies. 260 2.3. MPL Forwarder Behavior 262 If a DHCPv6 client requests and receives the MPL Parameter 263 Configuration Option, the node SHOULD join the MPL domain given by 264 the option and act as an MPL forwarder. Note that there may be cases 265 in which a node may fail to join a domain (or domains) due to local 266 resource constraints. Each joining node SHOULD configure its MPL 267 forwarder with the given parameter set for the MPL domain. 269 The priority of MPL Parameter Configurations applied to an MPL Domain 270 is as follows (high to low): 272 o Specific MPL Parameter Configuration to the MPL Domain 273 (option_len=32) 275 o Wildcard MPL Parameter Configuration (option_len=16) 277 o Default configuration given in the MPL specification. 279 Priority of other configurations such as manual configuration given 280 on a node is not defined in the document. 282 There MUST be no more than one MPL Parameter Configuration Option for 283 an MPL domain or the wildcard. Thus, the order of DHCPv6 options in 284 the packet has no effect on precedence. 286 A node SHOULD leave an MPL domain if it receives an updated and all- 287 valid MPL Parameter Configuration Options without a configuration for 288 the MPL domain, unless it has overriding manual configuration on the 289 MPL domain. In other words, if a node is configured to work as a MPL 290 Forwarder for a MPL domain regardless of DHCPv6 Options, the node MAY 291 stay on the MPL domain even if it receives an MPL Parameter 292 Configuration Option without configuration for the MPL domain. 294 MPL parameters may be updated occasionally. With stateful DHCPv6, 295 updates can be done when the renewal timer expires. Information 296 Refresh Time Option [RFC4242] shall be used to keep each forwarder 297 updated. 299 To reduce periodic update traffic, a node may try to use a very long 300 interval between updates. In this case, reconfigure messages may be 301 used to keep forwarder parameter sets synchronized. 303 2.4. DHCPv6 Server Behavior 305 Sections 17.2.2 and 18.2 of [RFC3315] govern server operation in 306 regards to option assignment. As a convenience to the reader, we 307 mention here that the server will send the MPL Parameter 308 Configuration Option only if it was configured with specific values 309 for the MPL Parameter Configuration Option and the client requested 310 it. 312 Servers MUST ignore an incoming MPL Parameter Configuration Option. 313 Servers MUST support multiple MPL Parameter Configuration Option, as 314 stated in section 2. 316 2.5. DHCPv6 Relay Behavior 318 It's never appropriate for a relay agent to add options to a message 319 heading toward the client, and relay agents don't actually construct 320 Relay-Reply messages anyway. There are no additional requirements 321 for relays. 323 2.6. Operational Considerations 325 [RFC6206] section 6 describe various problems that happens if the 326 trickle timers do not match between communicating nodes. To keep the 327 timers synchronized, it is RECOMMENDED not to update the parameters 328 of an MPL domain too often. A reasonable update rate would be once 329 per expected information refresh time interval, such as T1 in 330 [RFC3315] or Information Refresh Time in [RFC4242]. 332 3. IANA Considerations 334 IANA is requested to assign one option code for OPTION_MPL_PARAMETERS 335 from the "DHCP Option Codes" table of the Dynamic Host Configuration 336 Protocol for IPv6 (DHCPv6) Registry (http://www.iana.org/assignments/ 337 dhcpv6-parameters). 339 4. Security Considerations 341 There are detailed discussion on security threats on DHCPv6 in 342 Section 23 of RFC3315 [RFC3315], Section 23 of RFC7227 [RFC7227], and 343 Section 13 of [I-D.ietf-roll-trickle-mcast]. 345 In addition, a forged MPL parameter configuration may cause excessive 346 layer-2 broadcasting. Implementations should set reasonable bounds 347 for each parameter. For example, not too high DM/C_K, not too low DM 348 /C_IMIN, etc. These bounds may be implementation dependent or may be 349 derived from MAC/PHY specifications. DHCPv6 server and client 350 implementations need to take care in setting reasonable bounds for 351 each parameter in order to avoid overloading the network. 353 The DHCP server or the network itself should be trusted by some means 354 such as DHCPv6 authentications described in Section 21 of RFC3315 355 [RFC3315]. However, ROLL environment may expect less computing 356 resource, and DHCPv6 authentication may not available. In such 357 cases, other methods for security should be applied to a ROLL 358 network. Some ROLL specification such as ZigBee IP [ZigBeeIP] 359 expects RFC5191 [RFC5191] to authenticate joining nodes and all nodes 360 in the network can be trusted. To protect attacks from outside of 361 the network, unnecessary DHCPv6 packets should be filtered on the 362 border router between the ROLL network and the Internet. 364 5. References 366 5.1. Normative References 368 [I-D.ietf-roll-trickle-mcast] 369 Hui, J. and R. Kelsey, "Multicast Protocol for Low power 370 and Lossy Networks (MPL)", draft-ietf-roll-trickle- 371 mcast-12 (work in progress), June 2015. 373 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 374 Requirement Levels", BCP 14, RFC 2119, March 1997. 376 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 377 and M. Carney, "Dynamic Host Configuration Protocol for 378 IPv6 (DHCPv6)", RFC 3315, July 2003. 380 [RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh 381 Time Option for Dynamic Host Configuration Protocol for 382 IPv6 (DHCPv6)", RFC 4242, November 2005. 384 [RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko, 385 "The Trickle Algorithm", RFC 6206, DOI 10.17487/RFC6206, 386 March 2011, . 388 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 389 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 390 BCP 187, RFC 7227, May 2014. 392 5.2. Informative References 394 [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. 395 Yegin, "Protocol for Carrying Authentication for Network 396 Access (PANA)", RFC 5191, May 2008. 398 [ZigBeeIP] 399 ZigBee Alliance, "ZigBee IP Specification", Mar 2014. 401 Appendix A. Considerations on Inconsistent Parameter Set 403 This draft introduces dynamic update of MPL parameters. Because the 404 update process is not synchronized, nodes may have inconsistent 405 parameter sets. 407 Inconsistent parameter sets may reduce performance. On the other 408 hand, this situation will work as long as both new and old parameter 409 sets are reasonable parameter sets for a given communication load. 410 As the motivations for parameter update include update of the 411 environment, node density, or communication load, operators of MPL 412 networks shall be aware of unupdated nodes and make sure old and new 413 parameter sets are reasonable for the expected refresh intervals. 415 Appendix B. Update History (TO EDITORS: this section is intended to be 416 removed before this document becomes an RFC) 418 Updates on draft-ietf-roll-mpl-configuration-06 to draft-ietf-roll- 419 mpl-configuration-07: 421 o clearly stated multiple option support is mandatory (#171) 423 o operational consideration now refers RFC6206 and some texts are 424 moved to section 2.2 (#171) 426 o added more per-section reference to I-D.ietf-roll-trickle-mcast 427 (#171) 429 o field 'Z' clarified (#171, #172) 431 o fixed other nits (#171) 433 o clarified use of TUNIT, *_IMIN, and *_IMAX with reference to 434 RFC6206 (#172) 436 Updates on draft-ietf-roll-mpl-configuration-05 to draft-ietf-roll- 437 mpl-configuration-06: 439 o added description on manual (external) configurations 441 Updates on draft-ietf-roll-mpl-configuration-04 to draft-ietf-roll- 442 mpl-configuration-05: 444 o fixed *_IMAX definition as RFC6206 defines 446 o fixed *_EXP definition as draft-ietf-roll-trickle-mcast defines 448 o added references to RFC3315 and RFC7227 in security considerations 449 section 451 o added a paragraph on security consideration according to secdir 452 review 454 o fixed some nits and updated references 456 Updates on draft-ietf-roll-mpl-configuration-03 to draft-ietf-roll- 457 mpl-configuration-04: 459 o References updated (Non-normative -> Informative) 461 o IANA section is updated to make clear request of option ID 462 o Reserved numbers are clearly denoted 464 Updates on draft-ietf-roll-mpl-configuration-02 to draft-ietf-roll- 465 mpl-configuration-03: 467 o References updated 469 o Removed reference for DHCPv6 stateless reconfiguration as it has 470 expired 472 Updates on draft-ietf-roll-mpl-configuration-01 to draft-ietf-roll- 473 mpl-configuration-02: 475 o Short unsigned floating point is dropped (#159) 477 o Packed value is removed and now every value has its own byte(s) 478 (#159) 480 Updates on draft-ietf-roll-mpl-configuration-00 to draft-ietf-roll- 481 mpl-configuration-01: 483 o Operational considerations (normative) and appendix considerations 484 (non-normative) are added (Issue #157) 486 o More control on nodes / allow constrained nodes to ignore the 487 configuration: "the node s/SHOULD/MAY/ join the MPL domain given 488 by the option" (Issue #158) 490 Updates on draft-doi-roll-mpl-configuration-05 to draft-ietf-roll- 491 mpl-configuration-00: 493 o I-D renamed. 495 Authors' Addresses 497 Yusuke Doi 498 TOSHIBA Corporation 499 Komukai Toshiba Cho 1 500 Saiwai-Ku 501 Kawasaki, Kanagawa 2128582 502 JAPAN 504 Phone: +81-45-342-7230 505 Email: yusuke.doi@toshiba.co.jp 506 Matthew Gillmore 507 Itron, Inc 508 2111 N Molter Rd. 509 Liberty Lake, WA 99019 510 USA 512 Email: matthew.gillmore@itron.com