roll Y. Doi Internet-Draft TOSHIBA Corporation Intended status: Standards Track M. Gillmore Expires: August 17, 2014 Itron, Inc February 13, 2014 MPL Parameter Configuration Option for DHCPv6 draft-doi-roll-mpl-parameter-configuration-04 Abstract This draft is to define a way to configure MPL parameter via DHCPv6 option. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 17, 2014. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Doi & Gillmore Expires August 17, 2014 [Page 1] Internet-Draft MPL Conf. for DHCPv6 February 2014 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. MPL Parameter Configuration Option . . . . . . . . . . . . . . 3 2.1. Unsigned Short Floating Point . . . . . . . . . . . . . . . 4 2.2. MPL Parameter Configuration Option Format . . . . . . . . . 5 2.3. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . 6 2.4. MPL Forwarder Behavior . . . . . . . . . . . . . . . . . . 6 2.5. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . 7 2.6. DHCPv6 Relay Behavior . . . . . . . . . . . . . . . . . . . 7 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . . 8 5.2. Non-Normative References . . . . . . . . . . . . . . . . . 8 Appendix A. Update History . . . . . . . . . . . . . . . . . . . . 8 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Doi & Gillmore Expires August 17, 2014 [Page 2] Internet-Draft MPL Conf. for DHCPv6 February 2014 1. Introduction Multicast Protocol for Low power and Lossy Networks (MPL) [I-D.ietf-roll-trickle-mcast] defines a protocol to make a multicast network among low power and lossy network i.e. wireless mesh networks. MPL has various parameters to control its behavior and tradeoff between end-to-end delay and network utilization. In some environments, the parameters shall be configured carefully to meet each environment and requirement. According to the MPL draft section 5.4, the parameter should be same for all nodes within an MPL domain. And the MPL draft does not define a method to configure it. Some managed wireless mesh networks may have a DHCP server to configure network parameters with DHCP relay in each node. MPL parameters shall be considered as a part of network parameters (parameter shall match within an MPL domain). This document is to define the way to distribute parameters for MPL forwarders as a simple DHCPv6 [RFC3315] option. 2. MPL Parameter Configuration Option Per MPL domain, there are following 10 parameters. An MPL domain is defined by an MPL domain address. o PROACTIVE_FORWARDING o SEED_SET_ENTRY_LIFETIME o DATA_MESSAGE_IMIN o DATA_MESSAGE_IMAX o DATA_MESSAGE_K o DATA_MESSAGE_TIMER_EXPIRATIONS o CONTROL_MESSAGE_IMIN o CONTROL_MESSAGE_IMAX o CONTROL_MESSAGE_K o CONTROL_MESSAGE_TIMER_EXPIRATIONS One network may have multiple MPL domains with different configuration. To configure plural of MPL domains via DHCP, there may be more than one MPL Parameter Configuration Option given to DHCP Doi & Gillmore Expires August 17, 2014 [Page 3] Internet-Draft MPL Conf. for DHCPv6 February 2014 clients from a DHCP server. 2.1. Unsigned Short Floating Point MPL has many timer parameters. Expected range of the timers depends on the network topology or MAC/PHY nature. To accommodate wide range of timer values efficiently, the MPL Parameter Configuration Option uses base-10 unsigned short floating point number with 3-bit exponent and 13-bit significand defined as follows (exp. stands for exponent). 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | exp.| significand | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The represented value is (significand) * 10^(exp.). Minimum exponent is 0 (binary 000) and maximum is 6 (binary 110). exp=7 (binary 111) is reserved for future use. Minimum significand is 0 (all 0) and maximum is 8191 (all 1). Unlike IEEE754 half precision floating point (binary16), there is no sign bit (no negative value for a timer), exponent is not biased (no fractional value for a timer), no implicit leading 1 in siginificand, and base is 10. Therefore, there could be more than one representation for a value. Followings are examples of common timer values represented by unit of milliseconds. One second (1,000 ms.): exp = 3, significand = 1. 0x6001. One minute (60,000 ms.): exp = 4, significand = 6, 0x8006. One hour (3,600,000 ms.): exp = 5, significand = 36, 0xa024. One day (86,400,000 ms.): exp = 5, significand = 864, 0xa360 Maximum timer length represented by unsigned short floating point with millisecond precision is 8191*10^6 milliseconds (13 weeks 3 days 19 hours 16 minutes 40 seconds). With exponent and significand, an unsigned short floating point (usfp) can be encoded as follows. usfp = (exponent << 13)|(0x1fff & significand); Doi & Gillmore Expires August 17, 2014 [Page 4] Internet-Draft MPL Conf. for DHCPv6 February 2014 2.2. MPL Parameter Configuration Option Format To distribute a configuration of an MPL domain or a default value for all MPL domains (wildcard) under the network managed by the DHCP server, this document defines a DHCPv6 option format as follows. Short floating point format is used to describe wide range of timer values. 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_MPL_PARAMETERS | option_len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P| Z | C_K | Z2 | DM_K | SE_LIFETIME | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DM_IMIN | DM_IMAX | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DM_T_EXP | C_IMIN | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | C_IMAX | C_T_EXP | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (if option_len = 32 ) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPL Domain Address (128bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (cont'ed) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (cont'ed) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (cont'ed) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ OPTION_MPL_PARAMETERS: not yet assigned. option_len: Length of the option. It SHOULD be 16 (without MPL domain address) or 32 (with MPL domain address) P (1 bit): A flag to indicate PROACTIVE_FORWARDING Z (1 bit) Reserved. Should be 0. C_K (5 bits): Value of CONTROL_MESSAGE_K. Z2 (3 bit) Reserved. Should be all 0. Doi & Gillmore Expires August 17, 2014 [Page 5] Internet-Draft MPL Conf. for DHCPv6 February 2014 DM_K (5 bits): Value of DATA_MESSAGE_K. SE_LIFETIME: SEED_SET_ENTRY_LIFETIME. The value is milliseconds in unsigned short floating point. DM_IMIN: Value of DATA_MESSAGE_IMIN. The value is milliseconds in unsigned short floating point. DM_IMAX: Value of DATA_MESSAGE_IMAX. The value is milliseconds in unsigned short floating point. DM_T_EXP: Value of DATA_MESSAGE_TIMER_EXPIRATIONS. The value is milliseconds in unsigned short floating point. C_IMIN: Value of CONTROL_MESSAGE_IMIN. The value is milliseconds in unsigned short floating point. C_IMAX: Value of CONTROL_MESSAGE_IMAX. The value is milliseconds in unsigned short floating point. C_T_EXP: Value of CONTROL_MESSAGE_TIMER_EXPIRATIONS. The value is milliseconds in unsigned short floating point. 2.3. DHCPv6 Client Behavior Clients MAY request MPL Parameter Configuration Option, as described in RFC3315 [RFC3315], sections 17.1.1, 18.1.1, 18.1.3, 18.1.4, 18.1.5 and 22.7. As a convenience to the reader, we mention here that the client includes requested option codes in Option Request Option. Clients MUST discard MPL Parameter Configuration Option if it is invalid (i.e. it sets reserved bits or it has timers with reserved exp=7 in Unsigned Short Floating Point). 2.4. MPL Forwarder Behavior If a DHCPv6 client requests and receives MPL parameter configuration option, the node SHOULD join the MPL domain given by the option and act as an MPL forwarder. Nodes SHOULD configure MPL forwarders with the given parameters when it joins to the MPL domain. The priority of MPL Parameter configuration applied for an MPL Domain is as follows (high to low). o Specific MPL Parameter Configuration to the MPL Domain (optlen=32) o Wildcard MPL Parameter Configuration (optlen=16) Doi & Gillmore Expires August 17, 2014 [Page 6] Internet-Draft MPL Conf. for DHCPv6 February 2014 o Default configuration given in the MPL specification. There SHALL be no more than one MPL parameter configuration option for a MPL domain or the wildcard. Thus, the order of DHCPv6 option in the packet has no effect on precedence. A node MAY leave from an MPL domain if the node is attached to the MPL domain according to previously received MPL parameter configuration option, and, the node received updated MPL parameter configuration option without specific configuration option for the MPL domain. MPL parameter may be updated occasionally. With stateful DHCPv6, updates can be done when the renewal timer expires. However, on stateless DHCPv6 there are no way to update the parameters properly. There is a DHCPv6 option to push updates [I-D.jiang-dhc-stateless-reconfiguration]. 2.5. DHCPv6 Server Behavior Sections 17.2.2 and 18.2 of RFC3315 [RFC3315] govern server operation in regards to option assignment. As a convenience to the reader, we mention here that the server will send MPL Parameter Configuration Option only if configured with specific value for MPL Parameter Configuration Option and the client requested it. Servers MUST ignore incoming MPL Parameter Configuration Option. 2.6. DHCPv6 Relay Behavior It's never appropriate for a relay agent to add options to a message heading toward the client, and relay agents don't actually construct Relay-Reply messages anyway. There are no additional requirements for relays. 3. IANA Considerations A DHCPv6 option code for MPL Parameter Configuration Option needs to be assigned from IANA. 4. Security Considerations Forged option may cause too many MAC broadcasting. Reasonable bound of parameters (not too high K, not too low IMIN) may be defined by implementations or derived from MAC/PHY specifications. DHCP server or the network itself shall be trusted by some means including Doi & Gillmore Expires August 17, 2014 [Page 7] Internet-Draft MPL Conf. for DHCPv6 February 2014 network access control or DHCP authentications. 5. References 5.1. Normative References [I-D.ietf-roll-trickle-mcast] Hui, J. and R. Kelsey, "Multicast Forwarding Using Trickle", draft-ietf-roll-trickle-mcast-04 (work in progress), Feburary 2013. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. 5.2. Non-Normative References [I-D.jiang-dhc-stateless-reconfiguration] Jiang, S. and B. Liu, "Stateless Reconfiguration in Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", draft-jiang-dhc-stateless-reconfiguration-00 (work in progress), October 2013. Appendix A. Update History Updates on 03 to 04: o Added more sections according to dhc-options-guidelines o Removed 'no update' requirement on MPL forwarder behavior o Added reference to I-D.jiang-dhc-stateless-reconfiguration Updates on 02 to 03: o C flag is removed and wildcard shall be identified by optlen o Added some description on update of MPL parameters o Clearly stated there shall not be two or more configuration for an MPL domain and option order is not significant. Updates on 01 to 02: Doi & Gillmore Expires August 17, 2014 [Page 8] Internet-Draft MPL Conf. for DHCPv6 February 2014 o Added co-author Updates on 00 to 01: o Corrected target area, track, etc. Appendix B. Acknowledgements The authors thank Richard Kelsey and Yoshi Ohba for technical advices to improve this draft. Authors' Addresses Yusuke Doi TOSHIBA Corporation Komukai Toshiba Cho 1 Saiwai-Ku Kawasaki, Kanagawa 2128582 JAPAN Phone: +81-45-342-7230 Email: yusuke.doi@toshiba.co.jp URI: Matthew Gillmore Itron, Inc 2111 N Molter Rd. Liberty Lake, WA 99019 USA Email: matthew.gillmore@itron.com Doi & Gillmore Expires August 17, 2014 [Page 9]