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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: January 1, 2016 Itron, Inc 6 June 30, 2015 8 MPL Parameter Configuration Option for DHCPv6 9 draft-ietf-roll-mpl-parameter-configuration-05 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 be configured with a single set of MPL 20 parameters easily. 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 January 1, 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 . . . . . . . . . . . . . . . . . 5 60 2.3. MPL Forwarder Behavior . . . . . . . . . . . . . . . . . 5 61 2.4. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . 6 62 2.5. DHCPv6 Relay Behavior . . . . . . . . . . . . . . . . . . 6 63 2.6. Operational Considerations . . . . . . . . . . . . . . . 6 64 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 65 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 66 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 67 5.1. Normative References . . . . . . . . . . . . . . . . . . 7 68 5.2. Informative References . . . . . . . . . . . . . . . . . 8 69 Appendix A. Update History . . . . . . . . . . . . . . . . . . . 8 70 Appendix B. Considerations on Inconsistent Parameter Set . . . . 9 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 73 1. Introduction 75 Multicast Protocol for Low power and Lossy Networks (MPL) 76 [I-D.ietf-roll-trickle-mcast] defines a protocol to make a multicast 77 network among low-power and lossy networks, e.g., wireless mesh 78 networks. MPL has a set of parameters to control an MPL domain. The 79 parameters control the trade-off between end-to-end delay and network 80 utilization. In most environments, the default parameters are 81 acceptable. However, in some environments, the parameter set must be 82 configured carefully in order to meet the requirements of each 83 environment. According to the MPL document section 5.4, each 84 parameter in the set should be the same for all nodes within an MPL 85 domain, but the MPL document does not define a method to configure 86 the MPL parameter set. 88 Some managed wireless mesh networks may have a DHCP server to 89 configure network parameters. MPL parameter sets shall be considered 90 as a part of network parameters (nodes in an MPL domain should use an 91 identical parameter set). And a parameter set is required to 92 configure an MPL domain. 94 This document defines the way to distribute parameter sets for MPL 95 forwarders as a DHCPv6 [RFC3315] option. This document is intended 96 to follow [RFC7227] the guideline. 98 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 99 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 100 document are to be interpreted as described in [RFC2119]. 102 2. MPL Parameter Configuration Option 104 Per MPL domain, there are the following 10 parameters. An MPL domain 105 is defined by an MPL domain address. 107 o PROACTIVE_FORWARDING 109 o SEED_SET_ENTRY_LIFETIME 111 o DATA_MESSAGE_IMIN 113 o DATA_MESSAGE_IMAX 115 o DATA_MESSAGE_K 117 o DATA_MESSAGE_TIMER_EXPIRATIONS 119 o CONTROL_MESSAGE_IMIN 121 o CONTROL_MESSAGE_IMAX 123 o CONTROL_MESSAGE_K 125 o CONTROL_MESSAGE_TIMER_EXPIRATIONS 127 One network may have multiple MPL domains with different 128 configurations. To configure more than one MPL domain via DHCP, 129 there may be more than one MPL Parameter Configuration Option given 130 to DHCP clients by a DHCP server. 132 2.1. MPL Parameter Configuration Option Format 134 To distribute a configuration of an MPL domain or a default value for 135 all MPL domains (wildcard) under the network managed by the DHCP 136 server, this document defines a DHCPv6 option format as follows. 138 0 1 2 3 139 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 1 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 | OPTION_MPL_PARAMETERS | option_len | 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 |P| Z | TUNIT | SE_LIFETIME | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | DM_K | DM_IMIN | DM_IMAX | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | DM_T_EXP | C_K | C_IMIN > 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 >(cont'ed) | C_IMAX | C_T_EXP | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 (if option_len = 32 ) 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | MPL Domain Address (128bits) > 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 > (cont'ed) > 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 > (cont'ed) > 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 > (cont'ed) | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 OPTION_MPL_PARAMETERS: DHCPv6 option identifier (not yet assigned). 165 option_len: Length of the option. It SHOULD be 16 (without MPL 166 domain address) or 32 (with MPL domain address). 168 P (1 bit): A flag to indicate PROACTIVE_FORWARDING. The flag is set 169 if PROACTIVE_FORWARDING is true. 171 Z (7 bits): Reserved. Should be 0. 173 TUNIT (unsigned 8-bit integer): Unit time of timer parameters 174 (SE_LIFETIME, and *_IMIN) in this option. 0 and 0xff are reserved 175 and SHALL NOT be used. 177 SE_LIFETIME (unsigned 16-bit integer): SEED_SET_ENTRY_LIFETIME/TUNIT 178 in milliseconds. 0 and 0xffff are reserved and SHALL NOT be used. 180 DM_K (unsigned 8-bit integer): DATA_MESSAGE_K. 182 DM_IMIN (unsigned 16-bit integer): DATA_MESSAGE_IMIN/TUNIT in 183 milliseconds. 0 and 0xffff are reserved and SHALL NOT be used. 185 DM_IMAX (unsigned 8-bit integer): DATA_MESSAGE_IMAX. 0 and 0xff are 186 reserved and SHALL NOT be used. 188 DM_T_EXP (unsigned 16-bit integer): DATA_MESSAGE_TIMER_EXPIRATIONS. 189 0 and 0xffff are reserved and SHALL NOT be used. 191 C_K (unsigned 8-bit integer): CONTROL_MESSAGE_K. 193 C_IMIN (unsigned 16-bit integer): CONTROL_MESSAGE_IMIN/TUNIT in 194 milliseconds. 0 and 0xffff are reserved and SHALL NOT be used. 196 C_IMAX (unsigned 8-bit integer): CONTROL_MESSAGE_IMAX. 0 and 0xff 197 are reserved and SHALL NOT be used. 199 C_T_EXP (unsigned 16-bit integer): CONTROL_MESSAGE_TIMER_EXPIRATIONS 200 . 0 and 0xffff are reserved and SHALL NOT be used. 202 Note that all time values (Trickle timers and expiration periods) are 203 in TUNIT milliseconds precision. For example, if TUNIT is 20 and the 204 data message interval minimum (DATA_MESSAGE_IMIN) is 1000ms, then 205 DM_IMIN shall be set to 50. 207 2.2. DHCPv6 Client Behavior 209 Clients MAY request the MPL Parameter Configuration Option, as 210 described in [RFC3315], sections 17.1.1, 18.1.1, 18.1.3, 18.1.4, 211 18.1.5, and 22.7. As a convenience to the reader, we mention here 212 that the client includes requested option codes in the Option Request 213 Option. 215 Clients MUST discard the MPL Parameter Configuration Option if it is 216 invalid (e.g., it sets reserved bits). 218 2.3. MPL Forwarder Behavior 220 If a DHCPv6 client requests and receives the MPL Parameter 221 Configuration Option, the node SHOULD join the MPL domain given by 222 the option and act as an MPL forwarder. Note that there may be cases 223 in which a node may fail is to join a domain (or domains) due to 224 local resource constraints. Each joining node SHOULD configure its 225 MPL forwarder with the given parameter set for the MPL domain. 227 The priority of MPL Parameter Configurations applied to an MPL Domain 228 is as follows (high to low): 230 o Specific MPL Parameter Configuration to the MPL Domain 231 (option_len=32) 233 o Wildcard MPL Parameter Configuration (option_len=16) 235 o Default configuration given in the MPL specification. 237 There SHALL be no more than one MPL Parameter Configuration Option 238 for an MPL domain or the wildcard. Thus, the order of DHCPv6 options 239 in the packet has no effect on precedence. 241 A node MAY leave an MPL domain if the following two conditions are 242 satisfied. 1) The MPL domain is configured by a DHCPv6 option from a 243 DHCPv6 server previously. 2) The node has received an updated MPL 244 Parameter Configuration Option without a configuration for the MPL 245 domain. 247 MPL parameters may be updated occasionally. With stateful DHCPv6, 248 updates can be done when the renewal timer expires. Information 249 Refresh Time Option [RFC4242] shall be used to keep each forwarder 250 updated. 252 To reduce periodic update traffic, a node may try to use a very long 253 interval between updates. In the case, reconfigure messages may be 254 used to keep forwarder parameter sets synchronized. 256 2.4. DHCPv6 Server Behavior 258 Sections 17.2.2 and 18.2 of [RFC3315] govern server operation in 259 regards to option assignment. As a convenience to the reader, we 260 mention here that the server will send the MPL Parameter 261 Configuration Option only if it was configured with specific values 262 for the MPL Parameter Configuration Option and the client requested 263 it. 265 Servers SHALL ignore an incoming MPL Parameter Configuration Option. 267 2.5. DHCPv6 Relay Behavior 269 It's never appropriate for a relay agent to add options to a message 270 heading toward the client, and relay agents don't actually construct 271 Relay-Reply messages anyway. There are no additional requirements 272 for relays. 274 2.6. Operational Considerations 276 A parameter set for an MPL domain SHOULD NOT be updated more often 277 than twice of Information Refresh Time, even if the clients use 278 longer Information Refresh Time to reduce DHCPv6 load on the network. 280 If a node with an MPL forwarder configured by the MPL Parameter 281 Configuration Option failed to refresh the option within twice the 282 Information Refresh Time, it SHALL suspend the MPL forwarders of the 283 MPL domains configured by the option. MPL forwarders configured by 284 other methods such as static configuration file SHALL NOT be 285 suspended. 287 3. IANA Considerations 288 IANA is requested to assign one option code for OPTION_MPL_PARAMETERS 289 from the "DHCP Option Codes" table of the Dynamic Host Configuration 290 Protocol for IPv6 (DHCPv6) Registry. 292 4. Security Considerations 294 There are detailed discussion on security threats on DHCPv6 in 295 Section 23 of RFC3315 [RFC3315] and Section 23 of RFC7227 [RFC7227]. 297 In addition, a forged MPL parameter configuration may cause excessive 298 layer-2 broadcasting. Implementations should set reasonable bounds 299 for each parameter. For example, not too high DM/C_K, not too low DM 300 /C_IMIN, etc. These bounds may be implementation dependent or may be 301 derived from MAC/PHY specifications. DHCPv6 server and client 302 implementations need to take care in setting reasonable bounds for 303 each parameter in order to avoid overloading the network. 305 The DHCP server or the network itself should be trusted by some means 306 such as DHCPv6 authentications described in Section 21 of RFC3315 307 [RFC3315]. However, ROLL environment may expect less computing 308 resource, and DHCPv6 authentication may not available. In such 309 cases, other methods for security should be applied to a ROLL 310 network. Some ROLL specification such as ZigBee IP [ZigBeeIP] 311 expects RFC5191 [RFC5191] to authenticate joining nodes and all nodes 312 in the network can be trusted. To protect attacks from outside of 313 the network, unneccessary DHCPv6 packets should be filtered on the 314 border router between the ROLL network and the Internet. 316 5. References 318 5.1. Normative References 320 [I-D.ietf-roll-trickle-mcast] 321 Hui, J. and R. Kelsey, "Multicast Protocol for Low power 322 and Lossy Networks (MPL)", draft-ietf-roll-trickle- 323 mcast-12 (work in progress), June 2015. 325 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 326 Requirement Levels", BCP 14, RFC 2119, March 1997. 328 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 329 and M. Carney, "Dynamic Host Configuration Protocol for 330 IPv6 (DHCPv6)", RFC 3315, July 2003. 332 [RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh 333 Time Option for Dynamic Host Configuration Protocol for 334 IPv6 (DHCPv6)", RFC 4242, November 2005. 336 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 337 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 338 BCP 187, RFC 7227, May 2014. 340 5.2. Informative References 342 [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. 343 Yegin, "Protocol for Carrying Authentication for Network 344 Access (PANA)", RFC 5191, May 2008. 346 [ZigBeeIP] 347 ZigBee Alliance, "ZigBee IP Specification", Mar 2014. 349 Appendix A. Update History 351 Updates on draft-ietf-roll-mpl-configuration-03 to draft-ietf-roll- 352 mpl-configuration-05: 354 o fixed *_IMAX definition as RFC6206 defines 356 o fixed *_EXP definition as draft-ietf-roll-trickle-mcast defines 358 o added references to RFC3315 and RFC7227 in security considerations 359 section 361 o added a paragraph on security consideration according to secdir 362 review 364 o fixed some nits and updated references 366 Updates on draft-ietf-roll-mpl-configuration-03 to draft-ietf-roll- 367 mpl-configuration-04: 369 o References updated (Non-normative -> Informative) 371 o IANA section is updated to make clear request of option ID 373 o Reserved numbers are clearly denoted 375 Updates on draft-ietf-roll-mpl-configuration-02 to draft-ietf-roll- 376 mpl-configuration-03: 378 o References updated 380 o Removed reference for DHCPv6 stateless reconfiguration as it has 381 expired 383 Updates on draft-ietf-roll-mpl-configuration-01 to draft-ietf-roll- 384 mpl-configuration-02: 386 o Short unsigned floating point is dropped (#159) 388 o Packed value is removed and now every value has its own byte(s) 389 (#159) 391 Updates on draft-ietf-roll-mpl-configuration-00 to draft-ietf-roll- 392 mpl-configuration-01: 394 o Operational considerations (normative) and appendix considerations 395 (non-normative) are added (Issue #157) 397 o More control on nodes / allow constrained nodes to ignore the 398 configuration: "the node s/SHOULD/MAY/ join the MPL domain given 399 by the option" (Issue #158) 401 Updates on draft-doi-roll-mpl-configuration-05 to draft-ietf-roll- 402 mpl-configuration-00: 404 o I-D renamed. 406 Appendix B. Considerations on Inconsistent Parameter Set 408 This draft introduces dynamic update of MPL parameters. Because the 409 update process is not synchronized, nodes may have inconsistent 410 parameter sets. 412 Inconsistent parameter set may reduce performance. On the other 413 hand, this situation will work as long as both parameter sets are 414 reasonable parameter sets for a given communication load. As the 415 motivations for parameter update include update of the environment, 416 node density, or communication load, operators of MPL networks shall 417 be aware of unupdated nodes and make sure old and new parameter sets 418 are reasonable for the expected refresh intervals. 420 Authors' Addresses 422 Yusuke Doi 423 TOSHIBA Corporation 424 Komukai Toshiba Cho 1 425 Saiwai-Ku 426 Kawasaki, Kanagawa 2128582 427 JAPAN 429 Phone: +81-45-342-7230 430 Email: yusuke.doi@toshiba.co.jp 431 Matthew Gillmore 432 Itron, Inc 433 2111 N Molter Rd. 434 Liberty Lake, WA 99019 435 USA 437 Email: matthew.gillmore@itron.com