draft-ietf-roll-trickle-mcast-04.txt   draft-ietf-roll-trickle-mcast-05.txt 
ROLL J. Hui ROLL J. Hui
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track R. Kelsey Intended status: Standards Track R. Kelsey
Expires: August 29, 2013 Silicon Labs Expires: March 02, 2014 Silicon Labs
February 25, 2013 August 29, 2013
Multicast Protocol for Low power and Lossy Networks (MPL) Multicast Protocol for Low power and Lossy Networks (MPL)
draft-ietf-roll-trickle-mcast-04 draft-ietf-roll-trickle-mcast-05
Abstract Abstract
This document specifies the Multicast Protocol for Low power and This document specifies the Multicast Protocol for Low power and
Lossy Networks (MPL) that provides IPv6 multicast forwarding in Lossy Networks (MPL) that provides IPv6 multicast forwarding in
constrained networks. MPL avoids the need to construct or maintain constrained networks. MPL avoids the need to construct or maintain
any multicast forwarding topology, disseminating messages to all MPL any multicast forwarding topology, disseminating messages to all MPL
Forwarders in an MPL Domain. MPL uses the Trickle algorithm to Forwarders in an MPL Domain. MPL uses the Trickle algorithm to
manage message transmissions for both control and data-plane manage message transmissions for both control and data-plane
messages. Different Trickle parameter configurations allow MPL to messages. Different Trickle parameter configurations allow MPL to
trade between dissemination latency and transmission efficiency. trade between dissemination latency and transmission efficiency.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013. This Internet-Draft will expire on March 02, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 6 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Information Base Overview . . . . . . . . . . . . . . . . 7 4.1. MPL Domains . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Information Base Overview . . . . . . . . . . . . . . . . 6
4.3. Signaling Overview . . . . . . . . . . . . . . . . . . . . 9 4.3. Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
5. MPL Parameters and Constants . . . . . . . . . . . . . . . . . 10 4.4. Signaling Overview . . . . . . . . . . . . . . . . . . . 8
5.1. MPL Multicast Addresses . . . . . . . . . . . . . . . . . 10 5. MPL Parameters and Constants . . . . . . . . . . . . . . . . 9
5.2. MPL Message Types . . . . . . . . . . . . . . . . . . . . 10 5.1. MPL Multicast Addresses . . . . . . . . . . . . . . . . . 9
5.3. MPL Seed Identifiers . . . . . . . . . . . . . . . . . . . 10 5.2. MPL Message Types . . . . . . . . . . . . . . . . . . . . 9
5.4. MPL Forwarder Parameters . . . . . . . . . . . . . . . . . 10 5.3. MPL Seed Identifiers . . . . . . . . . . . . . . . . . . 9
5.5. MPL Trickle Parameters . . . . . . . . . . . . . . . . . . 11 5.4. MPL Forwarder Parameters . . . . . . . . . . . . . . . . 9
6. Protocol Message Formats . . . . . . . . . . . . . . . . . . . 13 5.5. MPL Trickle Parameters . . . . . . . . . . . . . . . . . 10
6.1. MPL Option . . . . . . . . . . . . . . . . . . . . . . . . 13 6. Protocol Message Formats . . . . . . . . . . . . . . . . . . 11
6.2. MPL Control Message . . . . . . . . . . . . . . . . . . . 14 6.1. MPL Option . . . . . . . . . . . . . . . . . . . . . . . 11
6.3. MPL Seed Info . . . . . . . . . . . . . . . . . . . . . . 15 6.2. MPL Control Message . . . . . . . . . . . . . . . . . . . 13
7. Information Base . . . . . . . . . . . . . . . . . . . . . . . 17 6.3. MPL Seed Info . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Local Interface Set . . . . . . . . . . . . . . . . . . . 17 7. Information Base . . . . . . . . . . . . . . . . . . . . . . 15
7.2. Domain Set . . . . . . . . . . . . . . . . . . . . . . . . 17 7.1. Local Interface Set . . . . . . . . . . . . . . . . . . . 15
7.3. Seed Set . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.2. Domain Set . . . . . . . . . . . . . . . . . . . . . . . 15
7.4. Buffered Message Set . . . . . . . . . . . . . . . . . . . 17 7.3. Seed Set . . . . . . . . . . . . . . . . . . . . . . . . 15
8. MPL Domains . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.4. Buffered Message Set . . . . . . . . . . . . . . . . . . 16
9. MPL Seed Sequence Numbers . . . . . . . . . . . . . . . . . . 20 8. MPL Seed Sequence Numbers . . . . . . . . . . . . . . . . . . 16
10. MPL Data Messages . . . . . . . . . . . . . . . . . . . . . . 21 9. MPL Data Messages . . . . . . . . . . . . . . . . . . . . . . 17
10.1. MPL Data Message Generation . . . . . . . . . . . . . . . 21 9.1. MPL Data Message Generation . . . . . . . . . . . . . . . 17
10.2. MPL Data Message Transmission . . . . . . . . . . . . . . 21 9.2. MPL Data Message Transmission . . . . . . . . . . . . . . 17
10.3. MPL Data Message Processing . . . . . . . . . . . . . . . 22 9.3. MPL Data Message Processing . . . . . . . . . . . . . . . 18
11. MPL Control Messages . . . . . . . . . . . . . . . . . . . . . 24 10. MPL Control Messages . . . . . . . . . . . . . . . . . . . . 19
11.1. MPL Control Message Generation . . . . . . . . . . . . . . 24 10.1. MPL Control Message Generation . . . . . . . . . . . . . 19
11.2. MPL Control Message Transmission . . . . . . . . . . . . . 24 10.2. MPL Control Message Transmission . . . . . . . . . . . . 20
11.3. MPL Control Message Processing . . . . . . . . . . . . . . 25 10.3. MPL Control Message Processing . . . . . . . . . . . . . 20
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 27 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
13.1. MPL Option Type . . . . . . . . . . . . . . . . . . . . . 28 12.1. MPL Option Type . . . . . . . . . . . . . . . . . . . . 22
13.2. MPL ICMPv6 Type . . . . . . . . . . . . . . . . . . . . . 28 12.2. MPL ICMPv6 Type . . . . . . . . . . . . . . . . . . . . 22
13.3. Well-known Multicast Addresses . . . . . . . . . . . . . . 28 12.3. Well-known Multicast Addresses . . . . . . . . . . . . . 23
14. Security Considerations . . . . . . . . . . . . . . . . . . . 29 13. Security Considerations . . . . . . . . . . . . . . . . . . . 23
15. Normative References . . . . . . . . . . . . . . . . . . . . . 30 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 14.1. Normative References . . . . . . . . . . . . . . . . . . 23
14.2. Informative References . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
Low power and Lossy Networks typically operate with strict resource Low power and Lossy Networks typically operate with strict resource
constraints in communication, computation, memory, and energy. Such constraints in communication, computation, memory, and energy. Such
resource constraints may preclude the use of existing IPv6 multicast resource constraints may preclude the use of existing IPv6 multicast
routing and forwarding mechanisms. Traditional IP multicast delivery routing and forwarding mechanisms. Traditional IP multicast delivery
typically relies on topology maintenance mechanisms to discover and typically relies on topology maintenance mechanisms to discover and
maintain routes to all subscribers of a multicast group. However, maintain routes to all subscribers of a multicast group (e.g.
maintaining such topologies in LLNs is costly and may not be feasible [RFC3973] [RFC4601]). However, maintaining such topologies in LLNs
given the available resources. is costly and may not be feasible given the available resources.
Memory constraints may limit devices to maintaining links/routes to Memory constraints may limit devices to maintaining links/routes to
one or a few neighbors. For this reason, the Routing Protocol for one or a few neighbors. For this reason, the Routing Protocol for
LLNs (RPL) specifies both storing and non-storing modes [RFC6550]. LLNs (RPL) specifies both storing and non-storing modes [RFC6550].
The latter allows RPL routers to maintain only one or a few default The latter allows RPL routers to maintain only one or a few default
routes towards a LLN Border Router (LBR) and use source routing to routes towards a LLN Border Router (LBR) and use source routing to
forward messages away from the LBR. For the same reasons, a LLN forward messages away from the LBR. For the same reasons, a LLN
device may not be able to maintain a multicast routing topology when device may not be able to maintain a multicast routing topology when
operating with limited memory. operating with limited memory.
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MPL Seed - An MPL Forwarder that generates MPL Data MPL Seed - An MPL Forwarder that generates MPL Data
Messages and serves as an entry point into an MPL Messages and serves as an entry point into an MPL
Domain. Domain.
MPL Seed Identifier - An unsigned integer that uniquely identifies an MPL Seed Identifier - An unsigned integer that uniquely identifies an
MPL Seed within an MPL Domain. MPL Seed within an MPL Domain.
3. Applicability Statement 3. Applicability Statement
This protocol is an IPv6 multicast forwarding protocol for Low-Power This protocol is an IPv6 multicast forwarding protocol designed for
and Lossy Networks. By implementing a controlled dissemination using the communication characteristics and resource constraints of Low-
the Trickle algorithm, this protocol is designed for networks that Power and Lossy Networks. By implementing controlled disseminations
communicate using low-power and lossy links with widely varying of multicast messages using the Trickle algorithm, this protocol is
topologies in both the space and time dimensions. designed for networks that communicate using low-power and lossy
links with widely varying topologies in both the space and time
dimensions.
While designed specifically for Low-Power and Lossy Networks, this
protocol is not limited to use over such networks. This protocol may
be applicable to any network where no multicast routing state is
desired. This protocol may also be used in environments where only a
subset of links are considered Low-Power and Lossy links.
Operationally, the scope of this protocol is administratively
determined. In other words, the scope of dissemination is determined
by routers configured to disallow transmission or reception of MPL
messages on a subset of interfaces.
A host need not be aware that their multicast is supported by MPL as
long as its attachment router forwards multicast messages between the
MPL Domain and the host. However, a host may choose to implement MPL
so that it can take advantage of the broadcast medium inherent in
many Low-Power and Lossy Networks and receive multicast messages
carried by MPL directly.
4. Protocol Overview 4. Protocol Overview
The goal of MPL is to deliver multicast messages to all interfaces The goal of MPL is to deliver multicast messages to all interfaces
that subscribe to the multicast messages' destination address within that subscribe to the multicast messages' destination address within
an MPL Domain. an MPL Domain.
4.1. Information Base Overview 4.1. MPL Domains
An MPL Domain is a scope zone, as defined in [RFC4007], in which MPL
Interfaces subscribe to the same MPL Domain Address and participate
in disseminating MPL Data Messages.
By default, an MPL Forwarder SHOULD participate in an MPL Domain
identified by the ALL_MPL_FORWARDERS multicast address with a scope
value of 3 (Realm-Local) [I-D.droms-6man-multicast-scopes]. When
used with MPL, Realm-Local scope is administratively defined and used
to define the boundaries of multicast message dissemination by MPL.
An MPL Forwarder MAY participate in additional MPL Domains identified
by other multicast addresses. An MPL Interface MUST subscribe to the
MPL Domain Addresses for the MPL Domains that it participates in.
The assignment of other multicast addresses is out of scope.
For each MPL Domain Address that an MPL Interface subscribes to, the
MPL Interface MUST also subscribe to the same MPL Domain Address with
a scope value of 2 (link-local) when reactive forwarding is in use
(i.e. when communicating MPL Control Messages).
4.2. Information Base Overview
A node records necessary protocol state in the following information A node records necessary protocol state in the following information
sets: sets:
o The Local Interface Set records the set of local MPL Interfaces o The Local Interface Set records the set of local MPL Interfaces
and the unicast addresses assigned to those MPL Interfaces. and the unicast addresses assigned to those MPL Interfaces.
o The Domain Set records the set of MPL Domain Addresses and the o The Domain Set records the set of MPL Domain Addresses and the
local MPL Interfaces that subscribe to those addresses. local MPL Interfaces that subscribe to those addresses.
o A Seed Set records information about received MPL Data Messages o A Seed Set records information about received MPL Data Messages
received from an MPL Seed within an MPL Domain. Each MPL Domain received from an MPL Seed within an MPL Domain. Each MPL Domain
has an associated Seed Set. A Seed Set maintains the minimum has an associated Seed Set. A Seed Set maintains the minimum
sequence number for MPL Data Messages that the MPL Forwarder is sequence number for MPL Data Messages that the MPL Forwarder is
willing to receive or has buffered in its Buffered Message Set willing to receive or has buffered in its Buffered Message Set
from an MPL Seed. MPL uses Seed Sets and Buffered Message Sets to from an MPL Seed. MPL uses Seed Sets and Buffered Message Sets to
determine when to accept an MPL Data Message, process its payload, determine when to accept an MPL Data Message, process its payload,
and retransmit it. and retransmit it.
o A Buffered Message Set records recently received MPL Data Messages o A Buffered Message Set records recently received MPL Data Messages
from an MPL Seed within an MPL Domain. Each MPL Domain has an from an MPL Seed within an MPL Domain. Each MPL Domain has an
associated Buffered Message Set. MPL Data Messages resident in a associated Buffered Message Set. MPL Data Messages resident in a
Buffered Message Set have sequence numbers that are greater than Buffered Message Set have sequence numbers that are greater than
or equal to the minimum threshold maintained in the corresponding or equal to the minimum threshold maintained in the corresponding
Seed Set. MPL uses Buffered Message Sets to store MPL Data Seed Set. MPL uses Buffered Message Sets to store MPL Data
Messages that may be transmitted by the MPL Forwarder for Messages that may be transmitted by the MPL Forwarder for
forwarding. forwarding.
4.2. Overview 4.3. Overview
MPL achieves its goal by implementing a controlled flood that MPL achieves its goal by implementing a controlled flood that
attempts to disseminate the multicast data message to all interfaces attempts to disseminate the multicast data message to all interfaces
within an MPL Domain. MPL performs the following tasks to within an MPL Domain. MPL performs the following tasks to
disseminate a multicast message: disseminate a multicast message:
o When having a multicast message to forward into an MPL Domain, the o When having a multicast message to forward into an MPL Domain, the
MPL Seed generates an MPL Data Message that includes the MPL MPL Seed generates an MPL Data Message that includes the MPL
Domain Address as the IPv6 Destination Address, the MPL Seed Domain Address as the IPv6 Destination Address, the MPL Seed
Identifier, a newly generated sequence number, and the multicast Identifier, a newly generated sequence number, and the multicast
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proactive forwarding for the MPL Data Message message. proactive forwarding for the MPL Data Message message.
Reactive Forwarding - With reactive forwarding, an MPL Forwarder Reactive Forwarding - With reactive forwarding, an MPL Forwarder
link-local multicasts MPL Control Messages using the Trickle link-local multicasts MPL Control Messages using the Trickle
algorithm [RFC6206]. MPL Forwarders use MPL Control Messages to algorithm [RFC6206]. MPL Forwarders use MPL Control Messages to
discover new MPL Data Messages that have not yet been received. discover new MPL Data Messages that have not yet been received.
When discovering that a neighboring MPL Forwarder has not yet When discovering that a neighboring MPL Forwarder has not yet
received an MPL Data Message, the MPL Forwarder schedules those received an MPL Data Message, the MPL Forwarder schedules those
MPL Data Messages for transmission using the Trickle algorithm. MPL Data Messages for transmission using the Trickle algorithm.
4.3. Signaling Overview Note that the use of proactive and reactive forwarding strategies
within the same MPL Domain are not mutually exclusive and may be used
simultaneously. For example, upon receiving a new MPL Data messages
when both proactive and reactive forwarding techniques are enabled,
an MPL Forwarder will proactively retransmit the MPL Data Message a
limited number of times and schedule further transmissions upon
receiving MPL Control Messages.
4.4. Signaling Overview
This protocol generates and processes the following messages: This protocol generates and processes the following messages:
MPL Data Message - Generated by an MPL Seed to deliver a multicast MPL Data Message - Generated by an MPL Seed to deliver a multicast
message across an MPL Domain. The MPL Data Message's source is an message across an MPL Domain. The MPL Data Message's source is an
address in the Local Interface Set of the MPL Seed that generated address in the Local Interface Set of the MPL Seed that generated
the message and is valid within the MPL Domain. The MPL Data the message and is valid within the MPL Domain. The MPL Data
Message's destination is the MPL Domain Address corresponding to Message's destination is the MPL Domain Address corresponding to
the MPL Domain. An MPL Data Message contains: the MPL Domain. An MPL Data Message contains:
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Message. Message.
* The sequence number of the MPL Seed that generated the MPL Data * The sequence number of the MPL Seed that generated the MPL Data
Message. Message.
* The original multicast message. * The original multicast message.
MPL Control Message - Generated by an MPL Forwarder to communicate MPL Control Message - Generated by an MPL Forwarder to communicate
information contained in an MPL Domain's Seed Set and Buffered information contained in an MPL Domain's Seed Set and Buffered
Message Set to neighboring MPL Forwarders. An MPL Control Message Message Set to neighboring MPL Forwarders. An MPL Control Message
contains a list of tuples for each entry in the Seed Set. Each contains a list of tuples for each entry in the Seed Set. Each
tuple contains: tuple contains:
* The minimum sequence number maintained in the Seed Set for the * The minimum sequence number maintained in the Seed Set for the
MPL Seed. MPL Seed.
* A bit-vector indicating the sequence numbers of MPL Data * A bit-vector indicating the sequence numbers of MPL Data
Messages resident in the Buffered Message Set for the MPL Seed, Messages resident in the Buffered Message Set for the MPL Seed,
where the first bit represents a sequence number equal to the where the first bit represents a sequence number equal to the
minimum threshold maintained in the Seed Set. minimum threshold maintained in the Seed Set.
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5. MPL Parameters and Constants 5. MPL Parameters and Constants
This section describes various program and networking parameters and This section describes various program and networking parameters and
constants used by MPL. constants used by MPL.
5.1. MPL Multicast Addresses 5.1. MPL Multicast Addresses
MPL makes use of MPL Domain Addresses to identify MPL Interfaces of MPL makes use of MPL Domain Addresses to identify MPL Interfaces of
an MPL Domain. By default, MPL Forwarders subscribe to the an MPL Domain. By default, MPL Forwarders subscribe to the
ALL_MPL_FORWARDERS multicast address with a scope value of 3 (subnet- ALL_MPL_FORWARDERS multicast address with a scope value of 3
local). [I-D.droms-6man-multicast-scopes].
For each MPL Domain Address that an MPL Interface subscribes to, the For each MPL Domain Address that an MPL Interface subscribes to, the
MPL Interface MUST also subscribe to the MPL Domain Address with a MPL Interface MUST also subscribe to the MPL Domain Address with a
scope value of 2 (link-local) when reactive forwarding is in use. scope value of 2 (link-local) when reactive forwarding is in use.
MPL Forwarders use the link-scoped MPL Domain Address to communicate MPL Forwarders use the link-scoped MPL Domain Address to communicate
MPL Control Messages to neighboring (i.e. on-link) MPL Forwarders. MPL Control Messages to neighboring (i.e. on-link) MPL Forwarders.
5.2. MPL Message Types 5.2. MPL Message Types
MPL defines an IPv6 Option for carrying an MPL Seed Identifier and a MPL defines an IPv6 Option for carrying an MPL Seed Identifier and a
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document. document.
5.4. MPL Forwarder Parameters 5.4. MPL Forwarder Parameters
PROACTIVE_FORWARDING A boolean value that indicates whether the MPL PROACTIVE_FORWARDING A boolean value that indicates whether the MPL
Forwarder should schedule MPL Data Message transmissions after Forwarder should schedule MPL Data Message transmissions after
receiving them for the first time. PROACTIVE_FORWARDING has a receiving them for the first time. PROACTIVE_FORWARDING has a
default value of TRUE. default value of TRUE.
SEED_SET_ENTRY_LIFETIME The minimum lifetime for an entry in the SEED_SET_ENTRY_LIFETIME The minimum lifetime for an entry in the
Seed Set. SEED_SET_ENTRY_LIFETIME has a default value of 30 Seed Set. SEED_SET_ENTRY_LIFETIME has a default value of 30
minutes. minutes.
It is RECOMMENDED that all MPL Forwarders use the same values for the It is RECOMMENDED that all MPL Forwarders use the same values for the
MPL Forwarder Parameters above for a given MPL Domain. The mechanism MPL Forwarder Parameters above for a given MPL Domain. The mechanism
for setting the MPL Forwarder Parameters is not specified within this for setting the MPL Forwarder Parameters is not specified within this
document. document.
5.5. MPL Trickle Parameters 5.5. MPL Trickle Parameters
As specified in [RFC6206], a Trickle timer runs for a defined As specified in [RFC6206], a Trickle timer runs for a defined
interval and has three configuration parameters: the minimum interval interval and has three configuration parameters: the minimum interval
size Imin, the maximum interval size Imax, and a redundancy constant size Imin, the maximum interval size Imax, and a redundancy constant
k. k.
This specification defines a fourth Trickle configuration parameter, This specification defines a fourth Trickle configuration parameter,
TimerExpirations, which indicates the number of Trickle timer TimerExpirations, which indicates the number of Trickle timer
expiration events that occur before terminating the Trickle expiration events that occur before terminating the Trickle algorithm
algorithm. for a given MPL Data Message or MPL Control Message.
Each MPL Forwarder uses the following Trickle parameters for MPL Data Each MPL Forwarder uses the following Trickle parameters for MPL Data
Message and MPL Control Message transmissions. Message and MPL Control Message transmissions.
DATA_MESSAGE_IMIN The minimum Trickle timer interval, as defined in DATA_MESSAGE_IMIN The minimum Trickle timer interval, as defined in
[RFC6206], for MPL Data Message transmissions. DATA_MESSAGE_IMIN [RFC6206], for MPL Data Message transmissions. DATA_MESSAGE_IMIN
has a default value of 10 times the worst-case link-layer latency. has a default value of 10 times the expected link-layer latency.
DATA MESSAGE_IMAX The maximum Trickle timer interval, as defined in DATA MESSAGE_IMAX The maximum Trickle timer interval, as defined in
[RFC6206], for MPL Data Message transmissions. DATA_MESSAGE_IMAX [RFC6206], for MPL Data Message transmissions. DATA_MESSAGE_IMAX
has a default value equal to DATA_MESSAGE_IMIN. has a default value equal to DATA_MESSAGE_IMIN.
DATA_MESSAGE_K The redundancy constant, as defined in [RFC6206], for DATA_MESSAGE_K The redundancy constant, as defined in [RFC6206], for
MPL Data Message transmissions. DATA_MESSAGE_K has a default MPL Data Message transmissions. DATA_MESSAGE_K has a default
value of 5. value of 1.
DATA_MESSAGE_TIMER_EXPIRATIONS The number of Trickle timer DATA_MESSAGE_TIMER_EXPIRATIONS The number of Trickle timer
expirations that occur before terminating the Trickle algorithm expirations that occur before terminating the Trickle algorithm's
for MPL Data Message transmissions. retransmission of a given MPL Data Message.
DATA_MESSAGE_TIMER_EXPIRATIONS has a default value of 3. DATA_MESSAGE_TIMER_EXPIRATIONS has a default value of 3.
CONTROL_MESSAGE_IMIN The minimum Trickle timer interval, as defined CONTROL_MESSAGE_IMIN The minimum Trickle timer interval, as defined
in [RFC6206], for MPL Control Message transmissions. in [RFC6206], for MPL Control Message transmissions.
CONTROL_MESSAGE_IMIN has a default value of 10 times the worst- CONTROL_MESSAGE_IMIN has a default value of 10 times the worst-
case link-layer latency. case link-layer latency.
CONTROL_MESSAGE_IMAX The maximum Trickle timer interval, as defined CONTROL_MESSAGE_IMAX The maximum Trickle timer interval, as defined
in [RFC6206], for MPL Control Message transmissions. in [RFC6206], for MPL Control Message transmissions.
CONTROL_MESSAGE_IMAX has a default value of 5 minutes. CONTROL_MESSAGE_IMAX has a default value of 5 minutes.
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CONTROL_MESSAGE_TIMER_EXPIRATIONS The number of Trickle timer CONTROL_MESSAGE_TIMER_EXPIRATIONS The number of Trickle timer
expirations that occur before terminating the Trickle algorithm expirations that occur before terminating the Trickle algorithm
for MPL Control Message transmissions. for MPL Control Message transmissions.
CONTROL_MESSAGE_TIMER_EXPIRATIONS has a default value of 10. CONTROL_MESSAGE_TIMER_EXPIRATIONS has a default value of 10.
Following [RFC6206], it is RECOMMENDED that all MPL Forwarders use Following [RFC6206], it is RECOMMENDED that all MPL Forwarders use
the same values for the Trickle Parameters above for a given MPL the same values for the Trickle Parameters above for a given MPL
Domain. The mechanism for setting the Trickle Parameters is not Domain. The mechanism for setting the Trickle Parameters is not
specified within this document. specified within this document.
The default Trickle parameter values above combined with the default
MPL Forwarder parameters in the prior section specify a forwarding
strategy that utilizes both proactive and reactive techniques. Using
these default values, an MPL Forwarder proactively transmits any new
MPL Data Messages it receives then uses MPL Control Messages to
trigger additional MPL Data Message retransmissions where message
drops are detected. Setting DATA_MESSAGE_IMAX to the same as
DATA_MESSAGE_IMIN in this case is acceptable since subsequent MPL
Data Message retransmissions are triggered by MPL Control Messages,
where CONTROL_MESSAGE_IMAX is greater than CONTROL_MESSAGE_IMIN.
6. Protocol Message Formats 6. Protocol Message Formats
The protocol messages generated and processed by an MPL Forwarder are The protocol messages generated and processed by an MPL Forwarder are
described in this section. described in this section.
6.1. MPL Option 6.1. MPL Option
The MPL Option is carried in MPL Data Messages in an IPv6 Hop-by-Hop The MPL Option is carried in MPL Data Messages in an IPv6 Hop-by-Hop
Options header, immediately following the IPv6 header. The MPL Options header, immediately following the IPv6 header. The MPL
Option has the following format: Option has the following format:
skipping to change at page 13, line 29 skipping to change at page 12, line 18
| Option Type | Opt Data Len | | Option Type | Opt Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| S |M|V| rsv | sequence | seed-id (optional) | | S |M|V| rsv | sequence | seed-id (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type MPL_OPT_TYPE Option Type MPL_OPT_TYPE
Opt Data Len Length of the Option Data field in octets. Opt Data Len Length of the Option Data field in octets.
S 2-bit unsigned integer. Identifies the length of S 2-bit unsigned integer. Identifies the length of
seed-id. 0 indicates that the seed-id is the IPv6 seed-id. 0 indicates that the seed-id is the
Source Address and not included in the MPL IPv6 Source Address and not included in the MPL
Option. 1 indicates that the seed-id is a 16-bit Option. 1 indicates that the seed-id is a 16-bit
unsigned integer. 2 indicates that the seed-id is unsigned integer. 2 indicates that the seed-id
a 64-bit unsigned integer. 3 indicates that the is a 64-bit unsigned integer. 3 indicates that
seed-id is a 128-bit unsigned integer. the seed-id is a 128-bit unsigned integer.
M 1-bit flag. 1 indicates that the value in M 1-bit flag. 1 indicates that the value in
sequence is known to be the largest sequence sequence is known to be the largest sequence
number that was received from the MPL Seed. number that was received from the MPL Seed.
V 1-bit flag. 0 indicates that the MPL Option V 1-bit flag. 0 indicates that the MPL Option
conforms to this specification. MPL Data conforms to this specification. MPL Data
Messages with an MPL Option in which this flag is Messages with an MPL Option in which this flag is
1 MUST be dropped. 1 MUST be dropped.
rsv 4-bit reserved field. MUST be set to 0 on rsv 4-bit reserved field. MUST be set to 0 on
transmission and ignored on reception. transmission and ignored on reception.
sequence 8-bit unsigned integer. Identifies relative sequence 8-bit unsigned integer. Identifies relative
ordering of MPL Data Messages from the MPL Seed ordering of MPL Data Messages from the MPL Seed
identified by seed-id. identified by seed-id.
skipping to change at page 14, line 44 skipping to change at page 13, line 33
contained in an MPL Domain's Seed Set and Buffered Message Set to contained in an MPL Domain's Seed Set and Buffered Message Set to
neighboring MPL Forwarders. The MPL Control Message has the neighboring MPL Forwarders. The MPL Control Message has the
following format: following format:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. MPL Seed Info[1..n] . . MPL Seed Info[0..n] .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Fields: IP Fields:
Source Address An IPv6 address in the AddressSet of the Source Address An IPv6 address in the AddressSet of the
corresponding MPL Interface and MUST be valid corresponding MPL Interface and MUST be valid
within the MPL Domain. within the MPL Domain.
Destination Address The link-scoped MPL Domain Address corresponding Destination Address The link-scoped MPL Domain Address corresponding
skipping to change at page 15, line 17 skipping to change at page 14, line 4
within the MPL Domain. within the MPL Domain.
Destination Address The link-scoped MPL Domain Address corresponding Destination Address The link-scoped MPL Domain Address corresponding
to the MPL Domain. to the MPL Domain.
Hop Limit 255 Hop Limit 255
ICMPv6 Fields: ICMPv6 Fields:
Type MPL_ICMP_TYPE Type MPL_ICMP_TYPE
Code 0 Code 0
Checksum The ICMP checksum. See [RFC4443]. Checksum The ICMP checksum. See [RFC4443].
MPL Seed Info[0..n] List of zero or more MPL Seed Info entries. MPL Seed Info[0..n] List of zero or more MPL Seed Info entries.
The MPL Control Message indicates the sequence numbers of MPL Data The MPL Control Message indicates the sequence numbers of MPL Data
Messages that are within the MPL Domain's Buffered Message Set. The Messages that are within the MPL Domain's Buffered Message Set. The
MPL Control Message also indicates the sequence numbers of MPL Data MPL Control Message also indicates the sequence numbers of MPL Data
Messages that an MPL Forwarder is willing to receive. The MPL Messages that an MPL Forwarder is willing to receive. The MPL
Control Message allows neighboring MPL Forwarders to determine Control Message allows neighboring MPL Forwarders to determine
whether there are any new MPL Data Messages to exchange. whether there are any new MPL Data Messages to exchange.
6.3. MPL Seed Info 6.3. MPL Seed Info
An MPL Seed Info encodes the minimum sequence number for an MPL Seed An MPL Seed Info encodes the minimum sequence number for an MPL Seed
maintained in the MPL Domain's Seed Set. The MPL Seed Info also maintained in the MPL Domain's Seed Set. The MPL Seed Info also
indicates the sequence numbers of MPL Data Messages generated by the indicates the sequence numbers of MPL Data Messages generated by the
MPL Seed that are stored within the MPL Domain's Buffered Message MPL Seed that are stored within the MPL Domain's Buffered Message
Set. The MPL Seed Info has the following format: Set. The MPL Seed Info has the following format:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| min-seqno | bm-len | S | seed-id (0/2/8/16 octets) | | min-seqno | bm-len | S | seed-id (0/2/8/16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. buffered-mpl-messages (variable length) . . buffered-mpl-messages (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
min-seqno 8-bit unsigned integer. The lower-bound sequence min-seqno 8-bit unsigned integer. The lower-bound sequence
number for the MPL Seed. number for the MPL Seed.
bm-len 6-bit unsigned integer. The size of buffered- bm-len 6-bit unsigned integer. The size of buffered-
mpl-messages in octets. mpl-messages in octets.
S 2-bit unsigned integer. Identifies the length of S 2-bit unsigned integer. Identifies the length of
seed-id. 0 indicates that the seed-id value is seed-id. 0 indicates that the seed-id value is
the IPv6 Source Address and not included in the the IPv6 Source Address and not included in the
MPL Seed Info. 1 indicates that the seed-id value MPL Seed Info. 1 indicates that the seed-id
is a 16-bit unsigned integer. 2 indicates that value is a 16-bit unsigned integer. 2 indicates
the seed-id value is a 64-bit unsigned integer. 3 that the seed-id value is a 64-bit unsigned
indicates that the seed-id is a 128-bit unsigned integer. 3 indicates that the seed-id is a
integer. 128-bit unsigned integer.
seed-id Variable-length unsigned integer. Indicates the seed-id Variable-length unsigned integer. Indicates the
MPL Seed associated with this MPL Seed Info. MPL Seed associated with this MPL Seed Info.
buffered-mpl-messages Variable-length bit vector. Identifies the buffered-mpl-messages Variable-length bit vector. Identifies the
sequence numbers of MPL Data Messages maintained sequence numbers of MPL Data Messages maintained
in the corresponding Buffered Message Set for the in the corresponding Buffered Message Set for the
MPL Seed. The i'th bit represents a sequence MPL Seed. The i'th bit represents a sequence
number of min-seqno + i. '0' indicates that the number of min-seqno + i. '0' indicates that the
corresponding MPL Data Message does not exist in corresponding MPL Data Message does not exist in
skipping to change at page 19, line 5 skipping to change at page 16, line 35
DataMessage - the MPL Data Message. DataMessage - the MPL Data Message.
All MPL Data Messages within a Buffered Message Set MUST have a All MPL Data Messages within a Buffered Message Set MUST have a
sequence number greater than or equal to MinSequence for the sequence number greater than or equal to MinSequence for the
corresponding SeedID. When increasing MinSequence for an MPL Seed, corresponding SeedID. When increasing MinSequence for an MPL Seed,
the MPL Forwarder MUST delete any MPL Data Messages from the the MPL Forwarder MUST delete any MPL Data Messages from the
corresponding Buffered Message Set that have sequence numbers less corresponding Buffered Message Set that have sequence numbers less
than MinSequence. than MinSequence.
8. MPL Domains 8. MPL Seed Sequence Numbers
An MPL Domain is a scope zone, as defined in [RFC4007], in which MPL
Interfaces subscribe to the same MPL Domain Address and participate
in disseminating MPL Data Messages.
By default, an MPL Forwarder SHOULD participate in an MPL Domain
identified by the ALL_MPL_FORWARDERS multicast address with a scope
value of 3 (subnet-local).
An MPL Forwarder MAY participate in additional MPL Domains identified
by other multicast addresses. An MPL Interface MUST subscribe to the
MPL Domain Addresses for the MPL Domains that it participates in.
The assignment of other multicast addresses is out of scope.
For each MPL Domain Address that an MPL Interface subscribes to, the
MPL Interface MUST also subscribe to the same MPL Domain Address with
a scope value of 2 (link-local) when reactive forwarding is in use
(i.e. when communicating MPL Control Messages).
9. MPL Seed Sequence Numbers
Each MPL Seed maintains a sequence number for each MPL Domain that it Each MPL Seed maintains a sequence number for each MPL Domain that it
serves. The sequence numbers are included in MPL Data Messages serves. The sequence numbers are included in MPL Data Messages
generated by the MPL Seed. The MPL Seed MUST increment the sequence generated by the MPL Seed. The MPL Seed MUST increment the sequence
number for each MPL Data Message that it generates for an MPL Domain. number for each MPL Data Message that it generates for an MPL Domain.
Implementations MUST follow the Serial Number Arithmetic as defined Implementations MUST follow the Serial Number Arithmetic as defined
in [RFC1982] when incrementing a sequence value or comparing two in [RFC1982] when incrementing a sequence value or comparing two
sequence values. This sequence number is used to establish a total sequence values. This sequence number is used to establish a total
ordering of MPL Data Messages generated by an MPL Seed for an MPL ordering of MPL Data Messages generated by an MPL Seed for an MPL
Domain. Domain.
10. MPL Data Messages 9. MPL Data Messages
10.1. MPL Data Message Generation 9.1. MPL Data Message Generation
MPL Data Messages are generated by MPL Seeds when these messages MPL Data Messages are generated by MPL Seeds when these messages
enter the MPL Domain. All MPL Data messages have the following enter the MPL Domain. All MPL Data messages have the following
properties: properties:
o The IPv6 Source Address MUST be an address in the AddressSet of a o The IPv6 Source Address MUST be an address in the AddressSet of a
corresponding MPL Interface and MUST be valid within the MPL corresponding MPL Interface and MUST be valid within the MPL
Domain. Domain.
o The IPv6 Destination Address MUST be set to the MPL Domain Address o The IPv6 Destination Address MUST be set to the MPL Domain Address
corresponding to the MPL Domain. corresponding to the MPL Domain.
o An MPL Data Message MUST contain an MPL Option in its IPv6 Header o An MPL Data Message MUST contain an MPL Option in its IPv6 Header
to identify the MPL Seed that generated the message and the to identify the MPL Seed that generated the message and the
ordering relative to other MPL Data Messages generated by the MPL ordering relative to other MPL Data Messages generated by the MPL
Seed. Seed.
When the source address is in the AddressList of an MPL Interface When the destination address is an MPL Domain Address and the source
corresponding to the MPL Domain Address and the destination address address is in the AddressLIst of an MPL Interface that belongs to
is the MPL Domain Address, the application message and the MPL Data that MPL Domain Address, the application message and the MPL Data
Message MAY be identical. In other words, the MPL Data Message may Message MAY be identical. In other words, the MPL Data Message may
contain a single IPv6 header that includes the MPL Option. contain a single IPv6 header that includes the MPL Option.
Otherwise, IPv6-in-IPv6 encapsulation MUST be used to satisfy the MPL Otherwise, IPv6-in-IPv6 encapsulation MUST be used to satisfy the MPL
Data Message requirements listed above [RFC2473]. The complete IPv6- Data Message requirements listed above [RFC2473]. The complete IPv6
in-IPv6 message forms an MPL Data Message. The outer IPv6 header -in-IPv6 message forms an MPL Data Message. The outer IPv6 header
conforms to the MPL Data Message requirements listed above. The conforms to the MPL Data Message requirements listed above. The
encapsulated IPv6 datagram encodes the multicast data message that is encapsulated IPv6 datagram encodes the multicast data message that is
communicated beyond the MPL Domain. communicated beyond the MPL Domain.
10.2. MPL Data Message Transmission 9.2. MPL Data Message Transmission
An MPL Forwarder manages transmission of MPL Data Messages in its An MPL Forwarder manages transmission of MPL Data Messages in its
Buffered Message Sets using the Trickle algorithm [RFC6206]. An MPL Buffered Message Sets using the Trickle algorithm [RFC6206]. An MPL
Forwarder MUST use a separate Trickle timer for each MPL Data Message Forwarder MUST use a separate Trickle timer for each MPL Data Message
that it is actively forwarding. In accordance with Section 5 of RFC that it is actively forwarding. In accordance with Section 5 of RFC
6206 [RFC6206], this document defines the following: 6206 [RFC6206], this document defines the following:
o This document defines a "consistent" transmission as receiving an o This document defines a "consistent" transmission as receiving an
MPL Data Message that has the same MPL Domain Address, seed-id, MPL Data Message that has the same MPL Domain Address, seed-id,
and sequence value as the MPL Data Message managed by the Trickle and sequence value as the MPL Data Message managed by the Trickle
skipping to change at page 22, line 25 skipping to change at page 18, line 25
As specified in [RFC6206], a Trickle timer has three variables: the As specified in [RFC6206], a Trickle timer has three variables: the
current interval size I, a time within the current interval t, and a current interval size I, a time within the current interval t, and a
counter c. MPL defines a fourth variable, e, which counts the number counter c. MPL defines a fourth variable, e, which counts the number
of Trickle timer expiration events since the Trickle timer was last of Trickle timer expiration events since the Trickle timer was last
reset. reset.
After DATA_MESSAGE_TIMER_EXPIRATIONS Trickle timer events, the MPL After DATA_MESSAGE_TIMER_EXPIRATIONS Trickle timer events, the MPL
Forwarder MUST disable the Trickle timer. When a buffered MPL Data Forwarder MUST disable the Trickle timer. When a buffered MPL Data
Message does not have an associated Trickle timer, the MPL Forwarder Message does not have an associated Trickle timer, the MPL Forwarder
MAY delete the message from the Buffered Message Set by advancing MAY delete the message from the Buffered Message Set by advancing
MinSequence of the corresponding MPL Seed in the Seed Set. When the MinSequence of the corresponding MPL Seed in the Seed Set. When the
MPL Forwarder no longer buffers any messages for an MPL Seed, the MPL MPL Forwarder no longer buffers any messages for an MPL Seed, the MPL
Forwarder MUST NOT increment MinSequence for that MPL Seed. Forwarder MUST NOT increment MinSequence for that MPL Seed.
When transmitting an MPL Data Message, the MPL Forwarder MUST either When transmitting an MPL Data Message, the MPL Forwarder MUST either
set the M flag to zero or set it to a level that indicates whether or set the M flag to zero or set it to a level that indicates whether or
not the message's sequence number is the largest value that has been not the message's sequence number is the largest value that has been
received from the MPL Seed. received from the MPL Seed.
10.3. MPL Data Message Processing 9.3. MPL Data Message Processing
Upon receiving an MPL Data Message, the MPL Forwarder first processes Upon receiving an MPL Data Message, the MPL Forwarder first processes
the MPL Option and updates the Trickle timer associated with the MPL the MPL Option and updates the Trickle timer associated with the MPL
Data Message if one exists. Data Message if one exists.
Upon receiving an MPL Data Message, an MPL Forwarder MUST perform one Upon receiving an MPL Data Message, an MPL Forwarder MUST perform one
of the following actions: of the following actions:
o Accept the message and enter the MPL Data Message in the MPL o Accept the message and enter the MPL Data Message in the MPL
Domain's Buffered Message Set. Domain's Buffered Message Set.
skipping to change at page 24, line 5 skipping to change at page 19, line 39
o If PROACTIVE_FORWARDING is true, the MPL Forwarder MUST initialize o If PROACTIVE_FORWARDING is true, the MPL Forwarder MUST initialize
and start a Trickle timer for the MPL Data Message. and start a Trickle timer for the MPL Data Message.
o If the MPL Control Message Trickle timer is not running and o If the MPL Control Message Trickle timer is not running and
CONTROL_MESSAGE_TIMER_EXPIRATIONS is non-zero, the MPL Forwarder CONTROL_MESSAGE_TIMER_EXPIRATIONS is non-zero, the MPL Forwarder
MUST initialize and start the MPL Control Message Trickle timer. MUST initialize and start the MPL Control Message Trickle timer.
o If the MPL Control Message Trickle timer is running, the MPL o If the MPL Control Message Trickle timer is running, the MPL
Forwarder MUST reset the MPL Control Message Trickle timer. Forwarder MUST reset the MPL Control Message Trickle timer.
11. MPL Control Messages 10. MPL Control Messages
11.1. MPL Control Message Generation 10.1. MPL Control Message Generation
An MPL Forwarder generates MPL Control Messages to communicate an MPL An MPL Forwarder generates MPL Control Messages to communicate an MPL
Domain's Seed Set and Buffered Message Set to neighboring MPL Domain's Seed Set and Buffered Message Set to neighboring MPL
Forwarders. Each MPL Control Message is generated according to Forwarders. Each MPL Control Message is generated according to
Section 6.2, with an MPL Seed Info for each entry in the MPL Domain's Section 6.2, with an MPL Seed Info for each entry in the MPL Domain's
Seed Set. Each MPL Seed Info entry has the following content: Seed Set. Each MPL Seed Info entry has the following content:
o S set to the size of the seed-id field in the MPL Seed Info entry. o S set to the size of the seed-id field in the MPL Seed Info entry.
o min-seqno set to MinSequence of the MPL Seed. o min-seqno set to MinSequence of the MPL Seed.
o bm-len set to the size of buffered-mpl-messages in octets. o bm-len set to the size of buffered-mpl-messages in octets.
o seed-id set to the MPL seed identifier. o seed-id set to the MPL seed identifier.
o buffered-mpl-messages with each bit representing whether or not an o buffered-mpl-messages with each bit representing whether or not an
MPL Data Message with the corresponding sequence number exists in MPL Data Message with the corresponding sequence number exists in
the Buffered Message Set. The i'th bit represents a sequence the Buffered Message Set. The i'th bit represents a sequence
number of min-seqno + i. '0' indicates that the corresponding MPL number of min-seqno + i. '0' indicates that the corresponding MPL
Data Message does not exist in the Buffered Message Set. '1' Data Message does not exist in the Buffered Message Set. '1'
indicates that the corresponding MPL Data Message does exist in indicates that the corresponding MPL Data Message does exist in
the Buffered Message Set. the Buffered Message Set.
11.2. MPL Control Message Transmission 10.2. MPL Control Message Transmission
An MPL Forwarder transmits MPL Control Messages using the Trickle An MPL Forwarder transmits MPL Control Messages using the Trickle
algorithm. An MPL Forwarder maintains a single Trickle timer for algorithm. An MPL Forwarder maintains a single Trickle timer for
each MPL Domain. When CONTROL_MESSAGE_TIMER_EXPIRATIONS is 0, the each MPL Domain. When CONTROL_MESSAGE_TIMER_EXPIRATIONS is 0, the
MPL Forwarder does not execute the Trickle algorithm and does not MPL Forwarder does not execute the Trickle algorithm and does not
transmit MPL Control Messages. In accordance with Section 5 of RFC transmit MPL Control Messages. In accordance with Section 5 of RFC
6206 [RFC6206], this document defines the following: 6206 [RFC6206], this document defines the following:
o This document defines a "consistent" transmission as receiving an o This document defines a "consistent" transmission as receiving an
MPL Control Message that indicates neither the receiving nor MPL Control Message that results in a determination that neither
transmitting node has any new MPL Data Messages to offer. the receiving nor transmitting node has any new MPL Data Messages
to offer.
o This document defines an "inconsistent" transmission as receiving o This document defines an "inconsistent" transmission as receiving
an MPL Control Message that indicates either the receiving or an MPL Control Message that results in a determination that either
transmitting node has at least one new MPL Data Message to offer. the receiving or transmitting node has at least one new MPL Data
Message to offer.
o This document defines an "event" as increasing MinSequence of any o The Trickle timer is reset in response to external "events." This
entry in the corresponding Seed Set or adding a message to the document defines an "event" as increasing MinSequence of any entry
in the corresponding Seed Set or adding a message to the
corresponding Buffered Message Set. corresponding Buffered Message Set.
o This document defines an MPL Control Message as a Trickle message. o This document defines an MPL Control Message as a Trickle message.
As specified in [RFC6206], a Trickle timer has three variables: the As specified in [RFC6206], a Trickle timer has three variables: the
current interval size I, a time within the current interval t, and a current interval size I, a time within the current interval t, and a
counter c. MPL defines a fourth variable, e, which counts the number counter c. MPL defines a fourth variable, e, which counts the number
of Trickle timer expiration events since the Trickle timer was last of Trickle timer expiration events since the Trickle timer was last
reset. After CONTROL_MESSAGE_TIMER_EXPIRATIONS Trickle timer events, reset. After CONTROL_MESSAGE_TIMER_EXPIRATIONS Trickle timer events,
the MPL Forwarder MUST disable the Trickle timer. the MPL Forwarder MUST disable the Trickle timer.
11.3. MPL Control Message Processing 10.3. MPL Control Message Processing
An MPL Forwarder processes each MPL Control Message that it receives An MPL Forwarder processes each MPL Control Message that it receives
to determine if it has any new MPL Data Messages to receive or offer. to determine if it has any new MPL Data Messages to receive or offer.
An MPL Forwarder determines if a new MPL Data Message has not been An MPL Forwarder determines if a new MPL Data Message has not been
received from a neighboring node if any of the following conditions received from a neighboring node if any of the following conditions
hold true: hold true:
o The MPL Control Message includes an MPL Seed that does not exist o The MPL Control Message includes an MPL Seed that does not exist
in the MPL Domain's Seed Set. in the MPL Domain's Seed Set.
skipping to change at page 27, line 5 skipping to change at page 21, line 49
When an MPL Forwarder determines that it has at least one MPL Data When an MPL Forwarder determines that it has at least one MPL Data
Message in its corresponding Buffered Message Set that has not yet Message in its corresponding Buffered Message Set that has not yet
been received by a neighbor, the MPL Forwarder MUST reset the MPL been received by a neighbor, the MPL Forwarder MUST reset the MPL
Control Message Trickle timer. Additionally, for each of those Control Message Trickle timer. Additionally, for each of those
entries in the Buffered Message Set, the MPL Forwarder MUST reset the entries in the Buffered Message Set, the MPL Forwarder MUST reset the
Trickle timer and reset e to 0. If a Trickle timer is not associated Trickle timer and reset e to 0. If a Trickle timer is not associated
with the MPL Data Message, the MPL Forwarder MUST initialize and with the MPL Data Message, the MPL Forwarder MUST initialize and
start a new Trickle timer. start a new Trickle timer.
12. Acknowledgements 11. Acknowledgements
The authors would like to acknowledge the helpful comments of Robert The authors would like to acknowledge the helpful comments of Robert
Cragie, Esko Dijk, Ralph Droms, Paul Duffy, Ulrich Herberg, Owen Cragie, Esko Dijk, Ralph Droms, Paul Duffy, Adrian Farrel, Ulrich
Kirby, Joseph Reddy, Don Sturek, Dario Tedeschi, and Peter van der Herberg, Owen Kirby, Kerry Lynn, Joseph Reddy, Michael Richardson,
Stok, which greatly improved the document. Don Sturek, Dario Tedeschi, and Peter van der Stok, which greatly
improved the document.
13. IANA Considerations 12. IANA Considerations
This document defines one IPv6 Option, a type that must be allocated This document defines one IPv6 Option, a type that must be allocated
from the IPv6 "Destination Options and Hop-by-Hop Options" registry from the IPv6 "Destination Options and Hop-by-Hop Options" registry
of [RFC2780]. of [RFC2780].
This document defines one ICMPv6 Message, a type that must be This document defines one ICMPv6 Message, a type that must be
allocated from the "ICMPv6 "type" Numbers" registry of [RFC4443]. allocated from the "ICMPv6 "type" Numbers" registry of [RFC4443].
This document registers two well-known multicast addresses from the This document registers two well-known multicast addresses from the
IPv6 multicast address space. IPv6 multicast address space.
13.1. MPL Option Type 12.1. MPL Option Type
IANA is requested to allocate an IPv6 Option Type from the IPv6 IANA is requested to allocate an IPv6 Option Type from the IPv6
"Destination Options and Hop-by-Hop Options" registry of [RFC2780], "Destination Options and Hop-by-Hop Options" registry of [RFC2780],
as specified in Table 1 below: as specified in Table 1 below:
+--------------+-----+-----+--------------+-------------+-----------+ +--------------+-------+-----+------------+-------------+-----------+
| Mnemonic | act | chg | rest | Description | Reference | | Mnemonic | act | chg | rest | Description | Reference |
+--------------+-----+-----+--------------+-------------+-----------+ +--------------+-------+-----+------------+-------------+-----------+
| MPL_OPT_TYPE | 01 | 1 | TBD | MPL Option | This | | MPL_OPT_TYPE | 01 | 1 | TBD | MPL Option | This |
| | | | (suggested | | Document | | | | | (suggested | | Document |
| | | | value 01101) | | | | | | | value | | |
+--------------+-----+-----+--------------+-------------+-----------+ | | | | 01101) | | |
+--------------+-------+-----+------------+-------------+-----------+
Table 1: IPv6 Option Type Allocation Table 1: IPv6 Option Type Allocation
13.2. MPL ICMPv6 Type 12.2. MPL ICMPv6 Type
IANA is requested to allocate an ICMPv6 Type from the "ICMPv6 "type" IANA is requested to allocate an ICMPv6 Type from the "ICMPv6 "type"
Numbers" registry of [RFC4443], as specified in Table 2 below: Numbers" registry of [RFC4443], as specified in Table 2 below:
+---------------+------+---------------------+---------------+ +---------------+------+---------------------+---------------+
| Mnemonic | Type | Name | Reference | | Mnemonic | Type | Name | Reference |
+---------------+------+---------------------+---------------+ +---------------+------+---------------------+---------------+
| MPL_ICMP_TYPE | TBD | MPL Control Message | This Document | | MPL_ICMP_TYPE | TBD | MPL Control Message | This Document |
+---------------+------+---------------------+---------------+ +---------------+------+---------------------+---------------+
Table 2: IPv6 Option Type Allocation Table 2: IPv6 Option Type Allocation
13.3. Well-known Multicast Addresses 12.3. Well-known Multicast Addresses
IANA is requested to allocate an IPv6 multicast address, with Group IANA is requested to allocate an IPv6 multicast address, with Group
ID in the range [0x01,0xFF] for 6LoWPAN compression [RFC6282], ID in the range [0x01,0xFF] for 6LoWPAN compression [RFC6282],
"ALL_MPL_FORWARDERS" from the "Variable Scope Multicast Addresses" "ALL_MPL_FORWARDERS" from the "Variable Scope Multicast Addresses"
sub-registry of the "INTERNET PROTOCOL VERSION 6 MULTICAST ADDRESSES" sub-registry of the "INTERNET PROTOCOL VERSION 6 MULTICAST ADDRESSES"
registry. registry.
14. Security Considerations 13. Security Considerations
MPL uses sequence numbers to maintain a total ordering of MPL Data MPL uses sequence numbers to maintain a total ordering of MPL Data
Messages from an MPL Seed. The use of sequence numbers allows a Messages from an MPL Seed. The use of sequence numbers allows a
denial-of-service attack where an attacker can spoof a message with a denial-of-service attack where an attacker can spoof a message with a
sufficiently large sequence number to: (i) flush messages from the sufficiently large sequence number to: (i) flush messages from the
Buffered Message List and (ii) increase the MinSequence value for an Buffered Message List and (ii) increase the MinSequence value for an
MPL Seed in the corresponding Seed Set. The former side effect allows MPL Seed in the corresponding Seed Set. The former side effect
an attacker to halt the forwarding process of any MPL Data Messages allows an attacker to halt the forwarding process of any MPL Data
being disseminated. The latter side effect allows an attacker to Messages being disseminated. The latter side effect allows an
prevent MPL Forwarders from accepting new MPL Data Messages that an attacker to prevent MPL Forwarders from accepting new MPL Data
MPL Seed generates while the sequence number is less than Messages that an MPL Seed generates while the sequence number is less
MinSequence. than MinSequence.
More generally, the basic ability to inject messages into a Low-power More generally, the basic ability to inject messages into a Low-power
and Lossy Network can be used as a denial-of-service attack and Lossy Network can be used as a denial-of-service attack
regardless of what forwarding protocol is used. For these reasons, regardless of what forwarding protocol is used. For these reasons,
Low-power and Lossy Networks typically employ link-layer security Low-power and Lossy Networks typically employ link-layer security
mechanisms to disable an attacker's ability to inject messages. mechanisms to disable an attacker's ability to inject messages.
To prevent attackers from injecting packets through an MPL Forwarder, To prevent attackers from injecting packets through an MPL Forwarder,
the MPL Forwarder MUST NOT accept or forward MPL Data Messages from a the MPL Forwarder MUST NOT accept or forward MPL Data Messages from a
communication interface that does not subscribe to the MPL Domain communication interface that does not subscribe to the MPL Domain
Address identified in message's destination address. Address identified in message's destination address.
MPL uses the Trickle algorithm to manage message transmissions and MPL uses the Trickle algorithm to manage message transmissions and
the security considerations described in [RFC6206] apply. the security considerations described in [RFC6206] apply.
15. Normative References 14. References
14.1. Normative References
[I-D.droms-6man-multicast-scopes]
Droms, R., "IPv6 Multicast Address Scopes", draft-droms-
6man-multicast-scopes-02 (work in progress), July 2013.
[RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
August 1996. August 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998. (IPv6) Specification", RFC 2460, December 1998.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, December 1998. IPv6 Specification", RFC 2473, December 1998.
[RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For [RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
Values In the Internet Protocol and Related Headers", Values In the Internet Protocol and Related Headers", BCP
BCP 37, RFC 2780, March 2000. 37, RFC 2780, March 2000.
[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and [RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
B. Zill, "IPv6 Scoped Address Architecture", RFC 4007, B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
March 2005. March 2005.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006. Version 6 (IPv6) Specification", RFC 4443, March 2006.
[RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko, [RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko,
skipping to change at page 31, line 5 skipping to change at page 24, line 38
[RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
September 2011. September 2011.
[RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R.,
Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Levis, P., Pister, K., Struik, R., Vasseur, JP., and R.
Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Alexander, "RPL: IPv6 Routing Protocol for Low-Power and
Lossy Networks", RFC 6550, March 2012. Lossy Networks", RFC 6550, March 2012.
14.2. Informative References
[RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol
Independent Multicast - Dense Mode (PIM-DM): Protocol
Specification (Revised)", RFC 3973, January 2005.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
Authors' Addresses Authors' Addresses
Jonathan W. Hui Jonathan W. Hui
Cisco Cisco
170 West Tasman Drive 170 West Tasman Drive
San Jose, California 95134 San Jose, California 95134
USA USA
Phone: +408 424 1547 Phone: +408 424 1547
Email: jonhui@cisco.com Email: jonhui@cisco.com
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