roll Y. Doi
Internet-Draft TOSHIBA Corporation
Intended status: Standards Track M. Gillmore
Expires: January 30, 2014 Itron, Inc
July 29, 2013
MPL Parameter Configuration Option for DHCPv6
draft-doi-roll-mpl-parameter-configuration-02
Abstract
This draft is to define a way to configure MPL parameter via DHCPv6
option.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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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 . . . . . . . . . 4
3. Operation of MPL Forwarders . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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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 via DHCPv6
[RFC3315] options.
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
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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 accomodate 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
representations 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).
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
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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|C|Z| C_K | Z2 | DM_K | SE_LIFETIME |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DM_IMIN | DM_IMAX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DM_T_EXP | C_IMIN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| C_IMAX | C_T_EXP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(if C = 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MPL Domain Address (128bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (cont'ed) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (cont'ed) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (cont'ed) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OPTION_MPL_PARAMETERS: not yet assigned.
option_len: Length of the option
P (1 bit): A flag to indicate PROACTIVE_FORWARDING
C (1 bit): MPL configuration type.
Z (1 bit) Reserved. Should be 0.
C_K (5 bits): Value of CONTROL_MESSAGE_K.
Z2 (3 bit) Reserved. Should be all 0.
DM_K (5 bits): Value of DATA_MESSAGE_K.
SE_LIFETIME: SEED_SET_ENTRY_LIFETIME. The value is milliseconds in
unsigned short floating point.
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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.
'C' defines configuration target type.
o '0' : Wildcard configuration. Only zero or one wildcard
configuration SHALL exist in a configuration set. Wildcard
configuration MUST NOT have a MPL domain address.
o '1' : Specific configuration for an MPL domain. The configuration
SHALL have (uncompressed) IPv6 multicast address as MPL Domain
Address.
3. Operation of MPL Forwarders
The node SHOULD join the MPL domain given and act as an MPL
Forwarder. Nodes SHOULD configure MPL forwarders 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 (C=1)
o Wildcard MPL Parameter Configuration (C=0)
o Default configuration given in the MPL specification.
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4. IANA Considerations
A DHCPv6 option code for MPL Parameter Configuration Option needs to
be assigned from IANA.
5. 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
network access control or DHCP authentications.
6. 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.
Appendix A. 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:
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Matthew Gillmore
Itron, Inc
2111 N Molter Rd.
Liberty Lake, WA 99019
USA
Email: matthew.gillmore@itron.com
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