Internet DRAFT - draft-doi-roll-mpl-parameter-configuration
draft-doi-roll-mpl-parameter-configuration
roll Y. Doi
Internet-Draft TOSHIBA Corporation
Intended status: Standards Track M. Gillmore
Expires: September 6, 2014 Itron, Inc
March 5, 2014
MPL Parameter Configuration Option for DHCPv6
draft-doi-roll-mpl-parameter-configuration-05
Abstract
This draft defines a way to configure MPL parameter set via DHCPv6
option. MPL has a set of parameters to control its behavior, and the
parameter set is often configured as a network-wide parameter because
the parameter set should be identical for each MPL forwarder in an
MPL domain. Using the MPL Parameter Configuration Option defined in
this document, a network can be configured with a single set of MPL
parameter easily.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 6, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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.
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 . . . . . . . . . . . . . . . . . . . . 8
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
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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 a set of parameters to control its behavior and
tradeoff between end-to-end delay and network utilization. In most
environments, the default parameters are acceptable. However, in
some environments, the parameter set must be configured carefully in
order to meet the requirements of each environment. According to the
MPL draft section 5.4, each parameter in the set should be same for
all nodes within an MPL domain. And the MPL draft does not define a
method to configure the MPL parameter set.
Some managed wireless mesh networks may have a DHCP server to
configure network parameters. MPL parameter set shall be considered
as a part of network parameters (nodes in an MPL domain should use an
identical parameter set). This document is to define the way to
distribute parameter sets 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
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configurations. To configure more than one MPL domain via DHCP,
there may be more than one MPL Parameter Configuration Option given
to DHCP 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.). The minimum
exponent is 0 (binary 000) and the maximum is 6 (binary 110). exp=7
(binary 111) is reserved for future use. The minimum significand is
0 (all 0) and the 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
millisecond.
One second (1,000 milliseconds): exp = 3, significand = 1, 0x6001.
One minute (60,000 milliseconds): exp = 4, significand = 6, 0x8006.
One hour (3,600,000 milliseconds): exp = 5, significand = 36,
0xa024.
One day (86,400,000 milliseconds): exp = 5, significand = 864,
0xa360
Maximum timer length represented by an 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.
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usfp = (exponent << 13)|(0x1fff & significand);
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: DHCPv6 option identifier (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): CONTROL_MESSAGE_K.
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Z2 (3 bits) Reserved. Should be all 0.
DM_K (5 bits): DATA_MESSAGE_K.
SE_LIFETIME: SEED_SET_ENTRY_LIFETIME. The unit is millisecond and
the type is unsigned short floating point.
DM_IMIN: DATA_MESSAGE_IMIN. The unit is millisecond and the type is
unsigned short floating point.
DM_IMAX: DATA_MESSAGE_IMAX. The unit is millisecond and the type is
unsigned short floating point.
DM_T_EXP: DATA_MESSAGE_TIMER_EXPIRATIONS. The unit is millisecond
and the type is unsigned short floating point.
C_IMIN: CONTROL_MESSAGE_IMIN. The unit is millisecond and the type
is unsigned short floating point.
C_IMAX: CONTROL_MESSAGE_IMAX. The unit is millisecond and the type
is unsigned short floating point.
C_T_EXP: CONTROL_MESSAGE_TIMER_EXPIRATIONS. The unit is millisecond
and the type is 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. Each node SHOULD configure its MPL
forwarder with the given parameter set for the MPL domain.
The priority of MPL Parameter Configuration applied for an MPL Domain
is as follows (high to low).
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o Specific MPL Parameter Configuration to the MPL Domain (optlen=32)
o Wildcard MPL Parameter Configuration (optlen=16)
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 options
in the packet has no effect on precedence.
A node MAY leave from an MPL domain if the following two conditions
are satisfied. 1) The MPL domain is configured by a DHCPv6 option
from a DHCPv6 server previously. 2) The node has received an updated
MPL Parameter Configuration Option without a configuration for the
MPL domain.
MPL parameter may be updated occasionally. With stateful DHCPv6,
updates can be done when the renewal timer expires. Information
Refresh Time Option [RFC4242] shall be used to keep each forwarders
updated.
To reduce periodical update traffic a node may try to use very long
interval between updates. In the case, reconfigure shall be used to
keep forwarder parameter sets synchronized. For stateless DHCPv6,
[I-D.jiang-dhc-stateless-reconfiguration] may be used (if approved).
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.
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4. Security Considerations
A forged option may cause excessive layer-2 broadcasting.
Implementations should set reasonable bounds for each parameter. For
example, not too high K, not too low IMIN, etc. These may be
implementation dependent or may be derived from MAC/PHY
specifications. DHCP server or the network itself shall be trusted
by some means including 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-07 (work in
progress), Feburary 2014.
[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.
[RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh
Time Option for Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 4242, November 2005.
5.2. Non-Normative References
[I-D.ietf-dhc-option-guidelines]
Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and
S. Krishnan, "Guidelines for Creating New DHCPv6 Options",
draft-ietf-dhc-option-guidelines-17 (work in progress),
January 2014.
[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-01 (work in
progress), February 2014.
Appendix A. Update History
Updates on 04 to 05:
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o Editorial fix and some clarification (thanks to Ted Lemon and
folks in IESG/RFC-Editor Language Editing Session)
o Added reference to RFC4242 and corrected renewal descriptions on
MPL forwarder behavior (thanks to Tatsuya Jinmei for pointing it
out)
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:
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.
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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
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