draft-ietf-roll-unaware-leaves-16.txt   draft-ietf-roll-unaware-leaves-17.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550, 8505 (if approved) M. Richardson Updates: draft-ietf-roll-efficient-npdao, 6550, M. Richardson
Intended status: Standards Track Sandelman 8505 (if approved) Sandelman
Expires: 10 December 2020 8 June 2020 Intended status: Standards Track 10 June 2020
Expires: 12 December 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-16 draft-ietf-roll-unaware-leaves-17
Abstract Abstract
This specification extends RFC6550 and RFC8505 to provide routing This specification extends RFC6550 and RFC8505 to provide routing
services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND
but do not participate to RPL. This specification also enables the but do not participate to RPL. This specification also enables the
RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG. RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG.
Status of This Memo Status of This Memo
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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
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://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
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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 10 December 2020. This Internet-Draft will expire on 12 December 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 7 3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 7
3.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 7 3.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 7
3.2. RFC 8505 Extended Address Registration . . . . . . . . . 7 3.2. RFC 8505 Extended Address Registration . . . . . . . . . 7
3.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.2. TID, I Field and Opaque Fields . . . . . . . . . . . 8 3.2.2. TID, I Field and Opaque Fields . . . . . . . . . . . 8
3.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 9 3.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 9
3.3.1. RFC 7400 Capability Indication Option . . . . . . . . 9 3.3.1. RFC 7400 Capability Indication Option . . . . . . . . 9
4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 10 4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 10
5. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 11 5. Updating draft-ietf-roll-efficient-npdao . . . . . . . . . . 11
6. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11 6. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11 7. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11
6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12 7.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11
6.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13 7.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12
6.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13 7.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13
6.2.3. Support of the Routing Header . . . . . . . . . . . . 13 7.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13
7. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13 7.2.3. Support of the Routing Header . . . . . . . . . . . . 13
8. Updated RPL Target option . . . . . . . . . . . . . . . . . . 14 8. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 15 9. Updated RPL Target Option . . . . . . . . . . . . . . . . . . 14
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 15 10. Protocol Operations for Unicast Addresses . . . . . . . . . . 15
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19 10.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 16
9.2.1. Perspective of the RUL Acting as 6LN . . . . . . . . 19 10.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 18
9.2.2. Perspective of the RPL Border Router Acting as 6LR . 20 10.2.1. Perspective of the RUL Acting as 6LN . . . . . . . . 18
9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 22 10.2.2. Perspective of the Border Router Acting as 6LR . . . 19
9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 23 10.2.3. Perspective of the RPL Root . . . . . . . . . . . . 22
10. Protocol Operations for Multicast Addresses . . . . . . . . . 24 10.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 26 11. Protocol Operations for Multicast Addresses . . . . . . . . . 23
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 12. Security Considerations . . . . . . . . . . . . . . . . . . . 24
12.1. Resizing the ARO Status values . . . . . . . . . . . . . 27 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
12.1.1. RPL Target Option Flags . . . . . . . . . . . . . . 27 13.1. Resizing the ARO Status values . . . . . . . . . . . . . 25
12.1.2. Address Registration Option Flags . . . . . . . . . 27 13.2. New DODAG Configuration Option Flag . . . . . . . . . . 25
12.2. New DODAG Configuration Option Flag . . . . . . . . . . 27 13.3. New RPL Target Option Flag . . . . . . . . . . . . . . . 26
12.3. New Subregistry for the RPL Non-Rejection Status 13.4. New Subregistry for the RPL Non-Rejection Status
values . . . . . . . . . . . . . . . . . . . . . . . . . 27 values . . . . . . . . . . . . . . . . . . . . . . . . . 26
12.4. New Subregistry for the RPL Rejection Status values . . 28 13.5. New Subregistry for the RPL Rejection Status values . . 26
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 13.6. Fixing the Address Registration Option Flags . . . . . . 27
14. Normative References . . . . . . . . . . . . . . . . . . . . 28 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27
15. Informative References . . . . . . . . . . . . . . . . . . . 31 15. Normative References . . . . . . . . . . . . . . . . . . . . 27
Appendix A. Example Compression . . . . . . . . . . . . . . . . 32 16. Informative References . . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 Appendix A. Example Compression . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices and low-power lossy transmissions, duty cycling of the LLN devices and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced the "Routing Protocol for Low Power and Lossy The IETF produced the "Routing Protocol for Low Power and Lossy
Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services
within such constraints. RPL belongs to the class of Distance-Vector within such constraints. RPL belongs to the class of Distance-Vector
protocols, which, compared to link-state protocols, limit the amount protocols, which, compared to link-state protocols, limit the amount
of topological knowledge that needs to be installed and maintained in of topological knowledge that needs to be installed and maintained in
each node. each node, and does not require convergence to avoid micro-loops.
To save signaling and routing state in constrained networks, RPL To save signaling and routing state in constrained networks, RPL
allows a routing stretch (see [RFC6687]), whereby routing is only allows a routing stretch (see [RFC6687]), whereby routing is only
performed along an acyclic graph optimized to reach a Root node, as performed along an acyclic graph optimized to reach a Root node, as
opposed to straight along a shortest path between 2 peers, whatever opposed to straight along a shortest path between 2 peers, whatever
that would mean in a given LLN. This trades the quality of peer-to- that would mean in a given LLN. This trades the quality of peer-to-
peer (P2P) paths for a vastly reduced amount of control traffic and peer (P2P) paths for a vastly reduced amount of control traffic and
routing state that would be required to operate a any-to-any shortest routing state that would be required to operate a any-to-any shortest
path protocol. Finally, broken routes may be fixed lazily and on- path protocol. Finally, broken routes may be fixed lazily and on-
demand, based on dataplane inconsistency discovery, which avoids demand, based on dataplane inconsistency discovery, which avoids
wasting energy in the proactive repair of unused paths. wasting energy in the proactive repair of unused paths.
To provide alternate paths in lossy networks, RPL forms Direction- To provide alternate paths in lossy networks, RPL forms Direction-
Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information
Solicitation (DIS) and DODAG Information Object (DIO) messages. For Sollicitation (DIS) and DODAG Information Object (DIO) messages. For
many of the nodes, though not all, a DODAG provides multiple many of the nodes, though not all, a DODAG provides multiple
forwarding solutions towards the Root of the topology via so-called forwarding solutions towards the Root of the topology via so-called
parents. RPL is designed to adapt to fuzzy connectivity, whereby the parents. RPL is designed to adapt to fuzzy connectivity, whereby the
physical topology cannot be expected to reach a stable state, with a physical topology cannot be expected to reach a stable state, with a
lazy control that creates the routes proactively, but may only fix lazy control that creates the routes proactively, but may only fix
them reactively, upon actual traffic. The result is that RPL them reactively, upon actual traffic. The result is that RPL
provides reachability for most of the LLN nodes, most of the time, provides reachability for most of the LLN nodes, most of the time,
but may not converge in the classical sense. but may not converge in the classical sense.
[RFC6550] provides unicast and multicast routing services to RPL- [RFC6550] provides unicast and multicast routing services to RPL-
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"When to use RFC 6553, 6554 and IPv6-in-IPv6" [USEofRPLinfo] "When to use RFC 6553, 6554 and IPv6-in-IPv6" [USEofRPLinfo]
introduces the term RPL-Aware-Leaf (RAL) for a Leaf that injects introduces the term RPL-Aware-Leaf (RAL) for a Leaf that injects
routes in RPL to manage the reachability of its own IPv6 addresses. routes in RPL to manage the reachability of its own IPv6 addresses.
In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf that In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf that
does not participate to RPL at all. A RUL is an IPv6 Host [RFC8504] does not participate to RPL at all. A RUL is an IPv6 Host [RFC8504]
that needs a RPL-Aware Router to obtain routing services over the RPL that needs a RPL-Aware Router to obtain routing services over the RPL
network. network.
This specification leverages the Address Registration mechanism This specification leverages the Address Registration mechanism
defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to
interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) to interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) and
request that the 6LR injects the relevant routing information for the request that the 6LR injects a Host route for the Registered Address
Registered Address in the RPL domain on its behalf. A RUL may be in the RPL routing on its behalf. A RUL may be unable to participate
unable to participate because it is very energy-constrained, or because it is very energy-constrained, or because it is unsafe to let
because it is unsafe to let it inject routes in RPL, in which case it inject routes in RPL, in which case using 6LowPAN ND as the
using 6LowPAN ND as the interface for the RUL limits the surface of interface for the RUL limits the surface of the possible attacks and
the possible attacks and optionally protects the address ownership. optionally protects the address ownership.
The Non-Storing Mode mechanisms are used to extend the routing state The RPL Non-Storing Mode mechanism is used to extend the routing
with connectivity to RULs even when the DODAG is operated in Storing state with connectivity to the RULs even when the DODAG is operated
Mode DODAGs. The unicast packet forwarding operation by the 6LR in Storing Mode. The unicast packet forwarding operation by the 6LR
serving a 6LN that is a RPL Leaf is described in [USEofRPLinfo]. serving a 6LN that is also a RUL is described in [USEofRPLinfo].
Examples of routing-agnostic 6LNs include lightly-powered sensors Examples of routing-agnostic 6LNs include lightly powered sensors
such as window smash sensor (alarm system), and kinetically powered such as window smash sensor (alarm system), and kinetically powered
light switches. Other applications of this specification may include light switches. Other applications of this specification may include
a smart grid network that controls appliances - such as washing a smart grid network that controls appliances - such as washing
machines or the heating system - in the home. Appliances may not machines or the heating system - in the home. Appliances may not
participate to the RPL protocol operated in the Smartgrid network but participate to the RPL protocol operated in the Smartgrid network but
can still interact with the Smartgrid for control and/or metering. can still interact with the Smartgrid for control and/or metering.
2. Terminology 2. Terminology
2.1. BCP 14 2.1. BCP 14
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and Lossy Networks (LLNs)" [RFC7102]. A glossary of classical and Lossy Networks (LLNs)" [RFC7102]. A glossary of classical
6LoWPAN acronyms is given in Section 2.3. Other terms in use in LLNs 6LoWPAN acronyms is given in Section 2.3. Other terms in use in LLNs
are found in "Terminology for Constrained-Node Networks" [RFC7228]. are found in "Terminology for Constrained-Node Networks" [RFC7228].
"RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by "RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by
a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract
information that RPL defines to be placed in data packets, e.g., as information that RPL defines to be placed in data packets, e.g., as
the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By
extension the term "RPI" is often used to refer to the RPL Option extension the term "RPI" is often used to refer to the RPL Option
itself. The DODAG Information Solicitation (DIS), Destination itself. The DODAG Information Sollicitation (DIS), Destination
Advertisement Object (DAO) and DODAG Information Object (DIO) Advertisement Object (DAO) and DODAG Information Object (DIO)
messages are also specified in [RFC6550]. The Destination Cleanup messages are also specified in [RFC6550]. The Destination Cleanup
Object (DCO) message is defined in [EFFICIENT-NPDAO]. Object (DCO) message is defined in [EFFICIENT-NPDAO].
This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware
Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node
(RAN) is introduced to refer to a node that is either an RAL or a RPL (RAN) is introduced to refer to a node that is either an RAL or a RPL
Router. As opposed to a RUL, an RAN manages the reachability of its Router. As opposed to a RUL, an RAN manages the reachability of its
addresses and prefixes by injecting them in RPL by itself. addresses and prefixes by injecting them in RPL by itself.
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(E)DAR: (Extended) Duplicate Address Request (E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation (E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection DAD: Duplicate Address Detection
DAO: Destination Advertisement Object (a RPL message) DAO: Destination Advertisement Object (a RPL message)
DCO: Destination Cleanup Object (a RPL message) DCO: Destination Cleanup Object (a RPL message)
DIS: DODAG Information Solicitation (a RPL message) DIS: DODAG Information Sollicitation (a RPL message)
DIO: DODAG Information Object (a RPL message) DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement NA: Neighbor Advertisement
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery ND: Neighbor Discovery
NS: Neighbor Solicitation NS: Neighbor Sollicitation
RA: Router Advertisement RA: Router Advertisement
ROVR: Registration Ownership Verifier ROVR: Registration Ownership Verifier
RPI: RPL Packet Information RPI: RPL Packet Information
RAL: RPL-Aware Leaf RAL: RPL-Aware Leaf
RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf) RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf)
RUL: RPL-Unaware Leaf RUL: RPL-Unaware Leaf
TID: Transaction ID (a sequence counter in the EARO) TID: Transaction ID (a sequence counter in the EARO)
3. 6LoWPAN Neighbor Discovery 3. 6LoWPAN Neighbor Discovery
3.1. RFC 6775 Address Registration 3.1. RFC 6775 Address Registration
The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861] The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861]
[RFC4862] was defined for transit media such a Ethernet. It is a [RFC4862] was defined for serial links and transit media such a
reactive protocol that relies heavily on multicast operations for Ethernet. It is a reactive protocol that relies heavily on multicast
address discovery (aka lookup) and duplicate address detection (DAD). operations for address discovery (aka lookup) and duplicate address
detection (DAD).
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
adapts IPv6 ND for operations over energy-constrained LLNs. The main adapts IPv6 ND for operations over energy-constrained LLNs. The main
functions of [RFC6775] are to proactively establish the Neighbor functions of [RFC6775] are to proactively establish the Neighbor
Cache Entry (NCE) in the 6LR and to prevent address duplication. To Cache Entry (NCE) in the 6LR and to prevent address duplication. To
that effect, [RFC6775] introduces a new unicast Address Registration that effect, [RFC6775] introduces a new unicast Address Registration
mechanism that contributes to reducing the use of multicast messages mechanism that contributes to reducing the use of multicast messages
compared to the classical IPv6 ND protocol. compared to the classical IPv6 ND protocol.
[RFC6775] defines a new Address Registration Option (ARO) that is [RFC6775] defines a new Address Registration Option (ARO) that is
carried in the unicast Neighbor Solicitation (NS) and Neighbor carried in the unicast Neighbor Sollicitation (NS) and Neighbor
Advertisement (NA) messages between the 6LoWPAN Node (6LN) and the Advertisement (NA) messages between the 6LoWPAN Node (6LN) and the
6LoWPAN Router (6LR). It also defines the Duplicate Address Request 6LoWPAN Router (6LR). It also defines the Duplicate Address Request
(DAR) and Duplicate Address Confirmation (DAC) messages between the (DAR) and Duplicate Address Confirmation (DAC) messages between the
6LR and the 6LoWPAN Border Router (6LBR). In an LLN, the 6LBR is the 6LR and the 6LoWPAN Border Router (6LBR). In an LLN, the 6LBR is the
central repository of all the Registered Addresses in its domain and central repository of all the Registered Addresses in its domain and
the source of truth for uniqueness and ownership. the source of truth for uniqueness and ownership.
3.2. RFC 8505 Extended Address Registration 3.2. RFC 8505 Extended Address Registration
"Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505] "Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505]
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Option Format Figure 1: EARO Option Format
3.2.1. R Flag 3.2.1. R Flag
[RFC8505] introduces the "R" flag in the EARO. The Registering Node [RFC8505] introduces the "R" flag in the EARO. The Registering Node
sets the "R" flag to indicate whether the 6LR should ensure sets the "R" flag to indicate whether the 6LR should ensure
reachability for the Registered Address. If the "R" flag is not set, reachability for the Registered Address. If the "R" flag is not set,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means, which means in a RPL network that it is an Address by other means. In a RPL network, this means that either it
RAN or that it uses another RPL Router for reachability services. is a RAN that injects the route by itself or that it uses another RPL
Router for reachability services.
This document specifies how the "R" flag is used in the context of This document specifies how the "R" flag is used in the context of
RPL. A 6LN is a RUL that requires reachability services for an IPv6 RPL. A 6LN is a RUL that requires reachability services for an IPv6
address if and only if it sets the "R" flag in the NS(EARO) used to address if and only if it sets the "R" flag in the NS(EARO) used to
register the address to a RPL border router acting as 6LR. Upon register the address to a RPL border router acting as 6LR. Upon
receiving the NS(EARO), the RPL router generates a DAO message for receiving the NS(EARO), the RPL router generates a DAO message for
the Registered Address if and only if the "R" flag is set. the Registered Address if and only if the "R" flag is set.
3.2.2. TID, I Field and Opaque Fields 3.2.2. TID, I Field and Opaque Fields
The EARO also includes a sequence counter called Transaction ID The EARO also includes a sequence counter called Transaction ID
(TID), which maps to the Path Sequence Field found in Transit Options (TID), which maps to the Path Sequence Field found in Transit Options
in RPL DAO messages. This is the reason why the support of [RFC8505] in RPL DAO messages. This is the reason why the support of [RFC8505]
by the RUL as opposed to only [RFC6775] is a prerequisite for this by the RUL as opposed to only [RFC6775] is a prerequisite for this
specification (more in Section 6.1). The EARO also transports an specification (more in Section 7.1). The EARO also transports an
Opaque field and an "I" field that describes what the Opaque field Opaque field and an associated "I" field that describes what the
transports and how to use it. Section 9.2.1 specifies the use of the Opaque field transports and how to use it. Section 10.2.1 specifies
"I" field and of the Opaque field by a RUL. the use of the "I" field and of the Opaque field by a RUL.
3.2.3. ROVR 3.2.3. ROVR
Section 5.3 of [RFC8505] introduces the Registration Ownership Section 5.3 of [RFC8505] introduces the Registration Ownership
Verifier (ROVR) field of variable length from 64 to 256 bits. The Verifier (ROVR) field of variable length from 64 to 256 bits. The
ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was
used to identify uniquely an Address Registration with the Link-Layer used to identify uniquely an Address Registration with the Link-Layer
address of the owner, but provided no protection against spoofing. address of the owner but provided no protection against spoofing.
"Address Protected Neighbor Discovery for Low-power and Lossy "Address Protected Neighbor Discovery for Low-power and Lossy
Networks" [AP-ND] leverages the ROVR field as a cryptographic proof Networks" [AP-ND] leverages the ROVR field as a cryptographic proof
of ownership to prevent a rogue third party from misusing the of ownership to prevent a rogue third party from misusing the
address. [AP-ND] adds a challenge/response exchange to the [RFC8505] address. [AP-ND] adds a challenge/response exchange to the [RFC8505]
Address Registration and enables Source Address Validation by a 6LR Address Registration and enables Source Address Validation by a 6LR
that will drop packets with a spoofed address. that will drop packets with a spoofed address.
This specification does not address how the protection by [AP-ND] This specification does not address how the protection by [AP-ND]
could be extended to RPL. On the other hand, it adds the ROVR to the could be extended to RPL. On the other hand, it adds the ROVR to the
DAO to build the proxied EDAR at the Root (see Section 8), which DAO to build the proxied EDAR at the Root (see Section 9), which
means that nodes that are aware of the Host route to the 6LN are made means that nodes that are aware of the Host route to the 6LN are made
aware of the associated ROVR as well. aware of the associated ROVR as well.
3.3. RFC 8505 Extended DAR/DAC 3.3. RFC 8505 Extended DAR/DAC
[RFC8505] updates the periodic DAR/DAC exchange that takes place [RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to
between the 6LR and the 6LBR using Extended DAR/DAC messages which carry the ROVR field. The EDAR/EDAC exchange takes place between the
can carry a ROVR field of variable size. The exchange is triggered 6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN
by an NS(EARO) message and is intended to create, refresh and delete to create, refresh and delete the corresponding state in the 6LBR.
the corresponding state in the 6LBR for a lifetime that is indicated The exchange is protected by the ARQ mechanism specified in 8.2.6 of
by the 6LN. It is protected by the ARQ mechanism specified in 8.2.6 [RFC6775], though in an LLN, a duration longer than the RETRANS_TIMER
of [RFC6775], though in an LLN, a duration longer than the [RFC4861] of 1 second may be necessary to cover the Turn Around Trip
RETRANS_TIMER [RFC4861] of 1 second may be necessary to cover the delay between the 6LR and the 6LBR.
Turn Around Trip delay from the 6LR to the 6LBR.
RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to
the Root that maintains the routing state in the RPL network for the the Root that maintains the routing state in the RPL network for the
lifetime indicated by the source of the DAO. This means that for lifetime indicated by the source of the DAO. This means that for
each address, there are two keep-alive messages that traverse the each address, there are two keep-alive messages that traverse the
whole network, one to the Root and one to the 6LBR. whole network, one to the Root and one to the 6LBR.
This specification removes the extraneous keep-alive across the LLN. This specification avoids the periodic EDAR/EDAC exchange across the
The 6LR turns the periodic Address Registration from the RUL into a LLN. The 6LR turns the periodic NS(EARO) from the RUL into a DAO
DAO message to the Root on every refresh, but it only generates the message to the Root on every refresh, but it only generates the EDAR
EDAR upon the first registration, for the purpose of DAD. Upon a upon the first registration, for the purpose of DAD, which must be
refresher DAO, the Root proxies the EDAR exchange to refresh the verified before the address is injected in RPL. Upon the DAO
state at the 6LBR on behalf of the 6LR, as illustrated in Figure 7. message, the Root proxies the EDAR exchange to refresh the state at
the 6LBR on behalf of the 6LR, as illustrated in Figure 7.
3.3.1. RFC 7400 Capability Indication Option 3.3.1. RFC 7400 Capability Indication Option
"6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power "6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the
6LoWPAN Capability Indication Option (6CIO) that enables a node to 6LoWPAN Capability Indication Option (6CIO) that enables a node to
expose its capabilities in Router Advertisement (RA) messages. expose its capabilities in Router Advertisement (RA) messages.
[RFC8505] defines a number of bits in the 6CIO, in particular: [RFC8505] defines a number of bits in the 6CIO, in particular:
L: Node is a 6LR. L: Node is a 6LR.
skipping to change at page 10, line 8 skipping to change at page 10, line 8
| Type | Length = 1 | Reserved |D|L|B|P|E|G| | Type | Length = 1 | Reserved |D|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: 6CIO flags Figure 2: 6CIO flags
A 6LR that can provide reachability services for a RUL in a RPL A 6LR that can provide reachability services for a RUL in a RPL
network as specified in this document SHOULD include a 6CIO in its RA network as specified in this document SHOULD include a 6CIO in its RA
messages and set the L, P and E flags as prescribed by [RFC8505], see messages and set the L, P and E flags as prescribed by [RFC8505], see
Section 6.1 for the behavior of the RUL. Section 7.1 for the corresponding behavior of the RUL.
4. Updating RFC 6550 4. Updating RFC 6550
This document specifies a new behavior whereby a 6LR injects DAO This document specifies a new behavior whereby a 6LR injects DAO
messages for unicast addresses (see Section 9) and multicast messages for unicast addresses (see Section 10) and multicast
addresses (see Section 10) on behalf of leaves that are not aware of addresses (see Section 11) on behalf of leaves that are not aware of
RPL. The addresses are exposed as external targets [RFC6550]. Per RPL. The RUL addresses are exposed as external targets [RFC6550].
[USEofRPLinfo], an IP-in-IP encapsulation that terminates at the RPL Conforming [USEofRPLinfo], an IP-in-IP encapsulation between the 6LR
Root is used to remove RPL artifacts and compression techniques that and the RPL Root is used to carry the RPL artifacts and remove them
may not be processed correctly outside of the RPL domain. when forwarding outside the RPL domain, e.g., to a RUL.
This document also synchronizes the liveness monitoring at the Root This document also synchronizes the liveness monitoring at the Root
and the 6LBR. A same value of lifetime is used for both, and a and the 6LBR. The same value of lifetime is used for both, and a
single keep-alive message, the RPL DAO, traverses the RPL network. A single keep-alive message, the RPL DAO, traverses the RPL network. A
new behavior is introduced whereby the RPL Root proxies the EDAR new behavior is introduced whereby the RPL Root proxies the EDAR
message to the 6LBR on behalf of the 6LR (more in Section 5), for any message to the 6LBR on behalf of the 6LR (more in Section 6), for any
6LN, RUL or RAN. 6LN, RUL or RAN.
Section 6.7.7 of [RFC6550] introduces RPL Target Option, which can be
used in RPL Control messages such as the DAO message to signal a
destination prefix. Section 9 adds the capabilities to transport the
ROVR field (see Section 3.2.3) and the IPv6 Address of the prefix
advertiser when the Target is a shorter prefix, signaled by a new "F"
flag. The position of the "F" flag is indicated in Section 13.3.
Section 6.7.6 of [RFC6550] defines the DODAG Configuration option Section 6.7.6 of [RFC6550] defines the DODAG Configuration option
with reserved flags. This specification defines the new "Root with reserved flags. This specification defines the new "Root
Proxies EDAR/EDAC" (P) flag and consumes one of the reserved flags to Proxies EDAR/EDAC" (P) flag and encodes it in one of these reserved
encode it. The "P" flag is set to indicate that the Root performs flags. The "P" flag is set to indicate that the Root performs the
the proxy operation and that all nodes in the RPL network must proxy operation, which implies that it supports the Updated RPL
refrain from renewing the 6LBR state directly. It also indicates Target Option (see Section 9). The position of the "P" flag is
that the Root supports the Updated RPL Target Option (see Section 8). indicated in Section 13.2.
The position of the "P" flag is indicated in Section 12.2.
Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in
the DIO Base Object. The new "P" flag is defined only for MOP value the DIO Base Object. The new "P" flag is defined only for MOP value
between 0 to 6. For a MOP value of 7 or above, the flag MAY be between 0 to 6. For a MOP value of 7 or above, the flag MAY be
redefined and MUST NOT be interpreted as "Root Proxies EDAR/EDAC" redefined and MUST NOT be interpreted as "Root Proxies EDAR/EDAC"
unless the specification of the MOP indicates to do so. unless the specification of the MOP indicates to do so.
The RPL Status defined in section 6.5.1 of [RFC6550] for use in the The RPL Status defined in section 6.5.1 of [RFC6550] for use in the
DAO-Ack message is extended to be used in the DCO messages DAO-ACK message is extended to be placed in DCO messages
[EFFICIENT-NPDAO] as well. Furthermore, this specification enables [EFFICIENT-NPDAO] as well. Furthermore, this specification enables
to use a RPL Status to embed the IPv6 ND Status defined for use in to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO
the EARO, more in Section 7. messages, embedded in a RPL Status, more in Section 8.
Section 6.7 of [RFC6550] introduces the RPL Control message Options 5. Updating draft-ietf-roll-efficient-npdao
such as the RPL Target Option that can be included in a RPL Control
message such as the DAO. Section 8 updates the RPL Target Option to
optionally transport the ROVR used in the IPv6 Registration (see
Section 3.2.3) so the RPL Root can generate a full EDAR message.
5. Updating RFC 8505 [EFFICIENT-NPDAO] defines the DCO for RPL Storing Mode only, with a
link-local scope. This specification extends its use to the Non-
Storing MOP, whereby the DCO is sent unicast by the Root directly to
the RAN that injected the DAO message for the considered target.
This document updates [RFC8505] to introduce the anonymous EDAR and This specification leverages the DCO between the Root and the 6LR
NS(EARO) messages. The anonymous messages are used for backward that serves as attachment router for a RUL.
compatibility. The anonymous messages are recognizable by a zero
ROVR field and can only be used as a refresher for a pre-existing
state associated to the Registered Address. More specifically, an
anonymous message can only increase the lifetime and/or increment the
TID of an existing state at the 6LBR.
Upon the renewal of a 6LoWPAN ND Address Registration, this 6. Updating RFC 8505
specification changes the behavior of a RPL Router acting as 6LR for
the registration. If the Root indicates the capability to proxy the
EDAR/EDAC exchange to the 6LBR by setting the "P" flag, the 6LR
refrains from sending an EDAR message; if the Root is separated from
the 6LBR, the Root regenerates the EDAR message to the 6LBR upon a
DAO message that signals the liveliness of the Address. The
regenerated message is anonymous if and only if the DAO is a legacy
message that does not carry a ROVR as specified in Section 8.
6. Requirements on the RPL-Unware Leaf This document updates [RFC8505] to change the behavior of a RPL
Router acting as 6LR in the 6LoWPAN ND Address Registration of a RUL
acting as 6LN. If the RPL Root advertise the capability to proxy the
EDAR/EDAC exchange to the 6LBR, the 6LR refrains from sending the
keep-alive EDAR message. Instead, if it is separated from the 6LBR,
the Root regenerates the EDAR message to the 6LBR periodically, upon
a DAO message that signals the liveliness of the Address.
7. Requirements on the RPL-Unware Leaf
This document provides RPL routing for a RUL, that is a 6LN acting as This document provides RPL routing for a RUL, that is a 6LN acting as
an IPv6 Host and not aware of RPL. Still, a minimal RPL-independent an IPv6 Host and not aware of RPL. Still, a minimal RPL-independent
functionality is required from the RUL to obtain routing services. functionality is required from the RUL to obtain routing services.
6.1. Support of 6LoWPAN ND 7.1. Support of 6LoWPAN ND
In order to obtain routing services from a 6LR, a RUL MUST implement In order to obtain routing services from a 6LR, a RUL MUST implement
[RFC8505] and set the "R" flag in the EARO. The RUL SHOULD support [RFC8505] and set the "R" flag in the EARO. The RUL SHOULD support
[AP-ND] and use it to protect the ownership of its addresses. The [AP-ND] to protect the ownership of its addresses. The RUL MUST NOT
RUL MUST NOT request routing services from a 6LR that does not request routing services from a 6LR that does not originate RA
originate RA messages with a CIO that has the L, P, and E flags all messages with a CIO that has the L, P, and E flags all set as
set as discussed in Section 3.3.1. discussed in Section 3.3.1, unless configured to do so.
A RUL that has multiple potential routers MUST prefer those that A RUL that may attach to multiple 6LRs MUST prefer those that provide
provide routing services. The RUL MUST register to all the 6LRs from routing services. The RUL MUST register to all the 6LRs from which
which it desires routing services. If there are no available it desires routing services.
routers, the connection of the RUL fails. The Address Registrations
SHOULD be performed in an RApid sequence, using the exact same EARO Parallel Address Registrations to several 6LRs SHOULD be performed in
for a same Address. Gaps between the Address Registrations will an rapid sequence, using the exact same EARO for the same Address.
invalidate some of the routes till the Address Registration finally Gaps between the Address Registrations will invalidate some of the
shows on those routes as well. routes till the Address Registration finally shows on those routes.
[RFC8505] introduces error Status values in the NA(EARO) which can be [RFC8505] introduces error Status values in the NA(EARO) which can be
received synchronously upon an NS(EARO) or asynchronously. The RUL received synchronously upon an NS(EARO) or asynchronously. The RUL
MUST support both cases and MUST refrain from using the address when MUST support both cases and MUST refrain from using the address when
the Status value indicates a rejection. the Status Value indicates a rejection.
6.2. External Routes and RPL Artifacts 7.2. External Routes and RPL Artifacts
Section 4.1 of [USEofRPLinfo] provides a set of rules that MUST be Section 4.1 of [USEofRPLinfo] provides a set of rules detailed below
followed for the routing operations to a RUL. that MUST be followed for routing packets from and to a RUL.
A 6LR that is upgraded to act as a border router for external routes A 6LR that acts as a border router for external routes advertises
advertises them using Non-Storing Mode DAO messages that are unicast them using Non-Storing Mode DAO messages that are unicast directly to
directly to the Root, even if the DODAG is operated in Storing Mode. the Root, even if the DODAG is operated in Storing Mode. Non-Storing
Non-Storing Mode routes are not visible inside the RPL domain and all Mode routes are not visible inside the RPL domain and all packets are
packets are routed via the Root. An upgraded Root tunnels the routed via the Root. The RPL Root tunnels the packets directly to
packets directly to the 6LR that advertised the external route which the 6LR that advertised the external route, which decapsulates and
decapsulates and forwards the original (inner) packet. forwards the original (inner) packet.
The RPL Non-Storing Mode signaling and the associated IP-in-IP The RPL Non-Storing MOP signaling and the associated IP-in-IP
encapsulated packets are normal traffic for the intermediate Routers. encapsulated packets appear as normal traffic to the intermediate
The support of external routes only impacts the Root and the 6LR. It Routers. The support of external routes only impacts the Root and
can be operated with legacy intermediate routers and does not add to the 6LR. It can be operated with legacy intermediate routers and
the amount of state that must be maintained in those routers. A RUL does not add to the amount of state that must be maintained in those
is an example of a destination that is reachable via an external routers. A RUL is an example of a destination that is reachable via
route which happens to be a Host route. an external route that happens to be also a Host route.
The RPL data packets always carry a Hop-by-Hop Header to transport a The RPL data packets always carry a Hop-by-Hop Header to transport a
RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates
its packets with an RPI, the 6LR needs to tunnel them to the Root to its packets with an RPI, the 6LR needs to tunnel them to the Root to
add the RPI. As a rule of a thumb and except for the very special add the RPI. As a rule of a thumb and except for the very special
case above, the packets from and to a RUL are always encapsulated case above, the packets from and to a RUL are always encapsulated
using an IP-in-IP tunnel between the Root and the 6LR that serves the using an IP-in-IP tunnel between the Root and the 6LR that serves the
RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4, RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4,
8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details). 8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details).
In Non-Storing Mode, packets going down carry a Source Routing Header In Non-Storing Mode, packets going down carry a Source Routing Header
(SRH). The IP-in-IP encapsulation, the RPI and the SRH are (SRH). The IP-in-IP encapsulation, the RPI and the SRH are
collectively called the "RPL artifacts" and can be compressed using collectively called the "RPL artifacts" and can be compressed using
[RFC8138]. Figure 11 presents an example compressed format for a [RFC8138]. Figure 10 presents an example compressed format for a
packet forwarded by the Root to a RUL in a Storing Mode DODAG. packet forwarded by the Root to a RUL in a Storing Mode DODAG.
The inner packet that is forwarded to the RUL may carry some RPL The inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it artifacts, e.g., an RPI if the original packet was generated with it,
and possibly an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the
expects the RUL to support the basic "IPv6 Node Requirements" RUL to support the basic "IPv6 Node Requirements" [RFC8504]. In
[RFC8504]. In particular the RUL is expected to ignore the RPL particular the RUL is expected to ignore the RPL artifacts that are
artifacts that are either consumed or not applicable to a Host. either consumed or not applicable to a Host.
A RUL is not expected to support the compression method defined in A RUL is not expected to support the compression method defined in
[RFC8138]. Unless configured otherwise, the border router MUST [RFC8138]. Unless configured otherwise, the border router MUST
uncompress the outgoing packet before forwarding over an external restore the outgoing packet before forwarding over an external route,
route, even if it is not the destination of the incoming packet, and even if it is not the destination of the incoming packet, and even
even when delivering to a RUL. when delivering to a RUL.
6.2.1. Support of IPv6 Encapsulation 7.2.1. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] sets the rules for forwarding IP-in-IP Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either
either to the final 6LN or to a parent 6LR. In order to enable IP- to the final destination (6LN) or to its attachment router (6LR). To
in-IP to the 6LN in Non-Storing Mode, the 6LN must be able to terminate the IP-in-IP tunnel, the 6LN, as an IPv6 Host, must be able
decapsulate the tunneled packet and either drop the inner packet if to decapsulate the tunneled packet and either drop the inner packet
it is not the final destination, or pass it to the upper layer for if it is not the final destination, or pass it to the upper layer for
further processing. Unless it is aware that the RUL can handle IP- further processing. Unless it is aware by other means that the RUL
in-IP properly, the Root that encapsulates a packet to a RUL can handle IP-in-IP properly, which is not mandated by [RFC8504], the
terminates the IP-in-IP tunnel at the parent 6LR . For that reason, Root terminates the IP-in-IP tunnel at the parent 6LR. It is thus
it is beneficial but not necessary for a RUL to support IP-in-IP. not necessary for a RUL to support IP-in-IP decapsulation.
6.2.2. Support of the HbH Header 7.2.2. Support of the HbH Header
A RUL is expected to process an unknown Option Type in a Hop-by-Hop A RUL is expected to process an Option Type in a Hop-by-Hop Header as
Header as prescribed by section 4.2 of [RFC8200]. This means in prescribed by section 4.2 of [RFC8200]. This means that the RPI with
particular that an RPI with an Option Type of 0x23 [USEofRPLinfo] is an Option Type of 0x23 [USEofRPLinfo] must be skipped when not
ignored when not understood. recognized.
6.2.3. Support of the Routing Header 7.2.3. Support of the Routing Header
A RUL is expected to process an unknown Routing Header Type as A RUL is expected to process an unknown Routing Header Type as
prescribed by section 4.4 of [RFC8200]. This means in particular prescribed by section 4.4 of [RFC8200]. This implies that the Source
that Routing Header with a Routing Type of 3 [RFC6554] is ignored Routing Header with a Routing Type of 3 [RFC6554] is ignored when the
when the Segments Left is zero, and the packet is dropped otherwise. Segments Left is zero, and the packet is dropped otherwise.
7. Updated RPL Status 8. Updated RPL Status
The RPL Status is defined in section 6.5.1 of [RFC6550] for use in The RPL Status is defined in section 6.5.1 of [RFC6550] for use in
the DAO-Ack message and values are assigned as follows: the DAO-ACK message and values are assigned as follows:
+---------+--------------------------------+ +---------+--------------------------------+
| Range | Meaning | | Range | Meaning |
+=========+================================+ +=========+================================+
| 0 | Success/Unqualified acceptance | | 0 | Success/Unqualified acceptance |
+---------+--------------------------------+ +---------+--------------------------------+
| 1-127 | Not an outright rejection | | 1-127 | Not an outright rejection |
+---------+--------------------------------+ +---------+--------------------------------+
| 128-255 | Rejection | | 128-255 | Rejection |
+---------+--------------------------------+ +---------+--------------------------------+
Table 1: RPL Status per RFC 6550 Table 1: RPL Status per RFC 6550
This specification extends the scope of the RPL Status to be used in The 6LoWPAN ND Status was defined for use in the EARO and the
RPL DCO messages. Furthermore, this specification enables to carry currently defined values are listed in table 1 of [RFC8505]. This
the IPv6 ND Status values defined for use in the EARO and initially specification enables to carry the 6LoWPAN ND Status values in RPL
listed in table 1 of [RFC8505] in a RPL Status. DAO and DCO messages, embedded in the RPL Status field.
Section 12.1 reduces the range of EARO Status values to 0-63 ensure To achieve this, Section 13.1 reduces the range of the EARO Status
that they fit within a RPL Status as shown in Figure 3. values to 0-63 to ensure that they fit within a RPL Status as shown
in Figure 3.
0
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|A| Value | |E|A| Value |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 3: RPL Status Format Figure 3: RPL Status Format
RPL Status subfields: The following RPL Status subfields are defined:
E: 1-bit flag. Set to indicate a rejection. When not set, a value E: 1-bit flag. Set to indicate a rejection. When not set, a value
of 0 indicates Success/Unqualified acceptance and other values of 0 indicates Success/Unqualified acceptance and other values
indicate "not an outright rejection" as per RFC 6550. indicate "not an outright rejection" as per RFC 6550.
A: 1-bit flag. Indicates the type of the Status value. A: 1-bit flag. Indicates the type of the Status Value.
Status Value: 6-bit unsigned integer. If the 'A' flag is set this Status Value: 6-bit unsigned integer. If the 'A' flag is set this
field transports a Status value defined for IPv6 ND EARO. When field transports a Status Value defined for IPv6 ND EARO. When
the 'A' flag is not set, the Status value is defined in a RPL the 'A' flag is not set, the Status Value is defined for RPL.
extension.
When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a EDAC When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a EDAC
message, the RPL Root MUST copy the ND Status unchanged in a RPL message, the RPL Root MUST copy the 6LoWPAN ND Status unchanged in
Status with the 'A' bit set. The RPL Root MUST set the 'E' flag for the RPL Status and set the 'A' bit. The RPL Root MUST set the 'E'
all values in range 1-10 which are all considered rejections. flag for Values in range 1-10 which are all considered rejections.
Conversely, the 6LR MUST copy the value of the RPL Status unchanged Reciprocally, upon a DCO or a DAO-ACK message from the RPL Root with
in the EARO of an NA message that is built upon a RPL Status with the a RPL Status that has the 'A' bit set, the 6LR MUST copy the RPL
'A' bit set in a DCO or a DAO-ACK message. Status Value unchanged in the Status field of the EARO when
generating an NA to the RUL.
8. Updated RPL Target option 9. Updated RPL Target Option
This specification updates the RPL Target option to transport the This specification updates the RPL Target Option to transport the
ROVR. This enables the RPL Root to generate a full EDAR message as ROVR that was also defined for 6LoWPAN ND messages. This enables the
opposed to an anonymous EDAR that has restricted properties. RPL Root to generate the proxied EDAR message to the 6LBR.
The Target Prefix field MUST be aligned to the next 4-byte boundary The new "F" flag is set to indicate that the Target Prefix field
after the size indicated by the Prefix Length. If necessary the contains the address of the advertising node in full, in which case
transported prefix MUST be padded with zeros. the length of the Target Prefix field is 16 bytes regardless of the
value of the Prefix Length field.
If the "F" flag is reset, the Target Prefix field MUST be aligned to
the next byte boundary after the size (expressed in bits) indicated
by the Prefix Length field. Padding bits are reserved and set to 0 a
prescribed by section 6.7.7 of [RFC6550].
With this specification the ROVR is the remainder of the RPL Target With this specification the ROVR is the remainder of the RPL Target
Option. The size of the ROVR is indicated in a new ROVR Size field Option. The size of the ROVR is indicated in a new ROVR Size field
that is encoded to map one-to-one with the Code Suffix in the EDAR that is encoded to map one-to-one with the Code Suffix in the EDAR
message (see table 4 of [RFC8505]). message (see table 4 of [RFC8505]).
The modified format is illustrated in Figure 4. It is backward The modified format is illustrated in Figure 4. It is backward
compatible with the Target Option in [RFC6550] and SHOULD be used as compatible with the Target Option in [RFC6550] and SHOULD be used as
a replacement. a replacement in new implementations even for Storing Mode operations
in preparation for upcoming security mechanisms based in the ROVR.
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 = 0x05 | Option Length |ROVRsz | Flags | Prefix Length | | Type = 0x05 | Option Length |ROVRsz |F|Flags| Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ +
| Target Prefix (Variable Length) | | Target Prefix (Variable Length) |
. Aligned to 4-byte boundary .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier (ROVR) ... ... Registration Ownership Verifier (ROVR) ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Updated Target Option Figure 4: Updated Target Option
New fields: New fields:
ROVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, or 4, ROVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, or 4,
denoting a ROVR size of 64, 128, 192, or 256 bits, respectively. denoting a ROVR size of 64, 128, 192, or 256 bits, respectively.
F: 1-bit flag. Set to indicate that Target Prefix field contains an
Address of prefix advertiser in full.
Registration Ownership Verifier (ROVR): This is the same field as in Registration Ownership Verifier (ROVR): This is the same field as in
the EARO, see [RFC8505] the EARO, see [RFC8505]
9. Protocol Operations for Unicast Addresses 10. Protocol Operations for Unicast Addresses
The description below assumes that the Root sets the "P" flag in the The description below assumes that the Root sets the "P" flag in the
DODAG Configuration Option and performs the EDAR proxy operation. DODAG Configuration Option and performs the EDAR proxy operation.
9.1. General Flow If the "P" flag is reset, the 6LR MUST generate the periodic EDAR
messages and process the returned status as specified in [RFC8505].
If the EDAC indicates success, the rest of the flow takes place as
presented but without the proxied EDAR/EDAC exchange.
10.1. General Flow
This specification eliminates the need to exchange keep-alive This specification eliminates the need to exchange keep-alive
Extended Duplicate Address messages, EDAR and EDAC, all the way from Extended Duplicate Address messages, EDAR and EDAC, all the way from
a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange
with the 6LBR is proxied by the RPL Root upon a DAO message that with the 6LBR is proxied by the RPL Root upon the DAO message that
refreshes the RPL routing state. Any combination of the logical refreshes the RPL routing state. The first EDAR upon a new
functions of 6LR, Root and 6LBR might be collapsed in a single node. Registration cannot be proxied, though, as it serves for the purpose
of DAD, which must be verified before the address is injected in RPL.
To achieve this, the lifetimes and sequence counters in 6LoWPAN ND
and RPL are aligned. In other words, the Path Sequence and the Path
Lifetime in the DAO message are taken from the Transaction ID and the
Address Registration lifetime in the NS(EARO) message from the 6LN.
In a RPL network where the function is enabled, refreshing the state In a RPL network where the function is enabled, refreshing the state
in the 6LBR is the responsibility of the Root. Consequently, only in the 6LBR is the responsibility of the Root. Consequently, only
addresses that are injected in RPL will be kept alive by the RPL addresses that are injected in RPL will be kept alive at the 6LBR by
Root. In a same fashion, if an additional routing protocol is the RPL Root.
deployed on a same network, that additional routing protocol may need
to handle the keep alive procedure for the addresses that it serves.
On the first Address Registration, illustrated in Figure 5 for RPL
Non-Storing Mode, the Extended Duplicate Address exchange takes place
as prescribed by [RFC8505]. If the exchange fails, the 6LR returns
an NA message with a negative status to the 6LN, the NCE is not
created and the address is not injected in RPL. If it is successful,
the 6LR creates an NCE and injects the Registered Address in RPL
using DAO/DAO-ACK exchanges all the way to the RPL DODAG Root.
The 6LN signals the termination of a registration with a 6LR using an
NS(EARO) with a Registration Lifetime set to 0. Upon this, the 6LR
ensures that an EDAR/EDAC exchange happens to clean up the state at
the 6LBR, either directly as shown in Figure 8, or, if the Root sets
the "P" flag, by setting the ROVR in the RPL Target Option.
Since RULs are advertised using Non-Storing Mode, the DAO message Since RULs are advertised using Non-Storing Mode, the DAO message
flow can be nested within the Address Registration flow as flow and the keep alive EDAR/EDAC can be nested within the Address
illustrated in Figure 5. (re)Registration flow. Figure 5 illustrates that for the first
Registration, both the DAD and the keep-alive EDAR/EDAC exchanges
happen in the same sequence.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | Extended DAR | | | Extended DAR |
| |--------------------------------->| | |--------------------------------->|
| | | | | |
| | Extended DAC | | | Extended DAC |
| |<---------------------------------| | |<---------------------------------|
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | (anonymous) EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
Figure 5: First RUL Registration Flow Figure 5: First RUL Registration Flow
To achieve this, the lifetimes and sequence counters in 6LoWPAN ND
and RPL are aligned. In other words, the Path Sequence and the Path
Lifetime in the DAO message are taken from the Transaction ID and the
Address Registration lifetime in the NS(EARO) message from the 6LN.
On the first Address Registration, illustrated in Figure 5 for RPL
Non-Storing Mode, the Extended Duplicate Address exchange takes place
as prescribed by [RFC8505]. If the exchange fails, the 6LR returns
an NA message with a negative status to the 6LN, the NCE is not
created and the address is not injected in RPL. If it is successful,
the 6LR creates an NCE and injects the Registered Address in the RPL
routing using a DAO/DAO-ACK exchange with the RPL DODAG Root.
An issue may be detected later, e.g., the address moves within the An issue may be detected later, e.g., the address moves within the
LLN or to a different Root on a backbone [6BBR]. In that case the LLN or to a different Root on a backbone [6BBR]. In that case the
value of the status that indicates the issue can be passed from value of the status that indicates the issue can be passed from
6LoWPAN ND to RPL and back as illustrated in Figure 6. 6LoWPAN ND to RPL and back as illustrated in Figure 6.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| | | NA(EARO, Status) | | | | NA(EARO, Status) |
| | |<-----------------| | | |<-----------------|
| | DCO(Status) | | | | DCO(Status) | |
| |<------------| | | |<------------| |
| NA(EARO, Status) | | | | NA(EARO, Status) | | |
|<-----------------| | | |<-----------------| | |
| | | | | | | |
Figure 6: Asynchronous Issue Figure 6: Asynchronous Issue
An Address re-Registration is performed by the 6LN to maintain the An Address re-Registration is performed by the 6LN to maintain the
NCE in the 6LR alive before lifetime expires. Upon an Address re- NCE in the 6LR alive before lifetime expires. Upon the refresh of an
Registration, as illustrated in Figure 7, the 6LR redistributes the Address re-Registration, as illustrated in Figure 7, the 6LR injects
Registered Address NS(EARO) in RPL. the Registered Address in RPL.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | (anonymous) EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 7: Next RUL Registration Flow Figure 7: Next RUL Registration Flow
This causes the RPL DODAG Root to refresh the state in the 6LBR with This is what causes the RPL Root to refresh the state in the 6LBR,
an EDAC message or an anonymous EDAC if the ROVR is not indicated in using an EDAC message. In case of an error in the proxied EDAR flow,
the Target Option. In both cases, the EDAC message sent in response the error is returned in the DAO-ACK using a RPL Status with the 'A'
by the 6LBR contains the actual value of the ROVR field for that flag set that imbeds a 6LoWPAN Status Value as discussed in
Address Registration. In case of an error on the proxied EDAR flow, Section 8.
the error MUST be returned in the DAO-ACK - if one was requested -
using a RPL Status with the 'A' flag set that imbeds a 6LoWPAN Status
value as discussed in Section 7.
If the Root could not return the negative Status in a DAO-ACK then it
sends an asynchronous Destination Cleanup Object (DCO) message
[EFFICIENT-NPDAO] to the 6LR by placing the negative Status in the
RPL Status with the 'A' flag set. Note that if both are used in a
short interval of time, the DAO-ACK and DCO messages are not
guaranteed to arrive in the same order at the 6LR.
The 6LR may receive a requested DAO-ACK even after it received a DCO, The 6LR may receive a requested DAO-ACK after it received an
but the negative Status in the DCO supercedes a positive Status in asynchronous DCO, but the negative Status in the DCO supersedes a
the DAO-ACK regardless of the order in which they are received. Upon positive Status in the DAO-ACK regardless of the order in which they
the DAO-ACK - or the DCO if it arrives first - the 6LR responds to are received. Upon the DAO-ACK - or the DCO if one arrives first -
the RUL with an NA(EARO). If the RPL Status has the 'A' flag set, the 6LR responds to the RUL with an NA(EARO).
then the ND Status is extracted and passed in the EARO; else, if the
'E' flag is set, indicating a rejection, then the status 4 "Removed"
is used; else, the ND Status of 0 indicating "Success" is used.
The RUL may terminate the registration at anytime by using a The RUL MAY terminate the registration at any time by using a
Registration Lifetime of 0. This specification expects that the RPL Registration Lifetime of 0. This specification requires that the RPL
Target option transports a ROVR. If that is the case, the normal Target Option transports the ROVR. This way, the same flow as the
heartbeat flow is sufficient to inform the 6LBR using the Root as heartbeat flow is sufficient to inform the 6LBR using the Root as
proxy as illustrated in Figure 7. If the 6LR could not add the ROVR proxy as illustrated in Figure 7.
to the DAO message, then it MUST inform the 6LBR separately using as
illustrated in Figure 8.
6LN/RUL 6LR Root 6LBR
| | | |
|NS(EARO,Lifet=0)| | |
|--------------->| |
| | Extended DAR |
| |------------------------------------->|
| | |
| | Extended DAC |
| |<-------------------------------------|
| | DAO (Lifetime=0) | |
| |----------------->| |
| | | anonymous EDAR |
| | |------------------>|
| | | EDAC |
| | |<------------------|
| | DAO-ACK | |
| |<-----------------| |
| NA(EARO) | | |
|<---------------| | |
| | | |
| <Remove NCE> | |
| | | |
Figure 8: Last RUL Registration Flow, No ROVR Any combination of the logical functions of 6LR, Root and 6LBR might
be collapsed in a single node.
9.2. Detailed Operation 10.2. Detailed Operation
9.2.1. Perspective of the RUL Acting as 6LN 10.2.1. Perspective of the RUL Acting as 6LN
This specification does not alter the operation of a 6LoWPAN ND- This specification does not alter the operation of a 6LoWPAN ND-
compliant 6LN, and a RUL is expected to operate as follows: compliant 6LN, and a RUL is expected to operate as follows:
1. The 6LN obtains an IPv6 global address, either using Stateless 1. The 6LN obtains an IPv6 global address, either using Stateless
Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix
Information Option (PIO) [RFC4861] found in an RA message, or Information Option (PIO) [RFC4861] found in an RA message, or
some other means such as DHCPv6 [RFC3315]. some other means such as DHCPv6 [RFC3315].
2. Once it has formed an address, the 6LN (re)registers its address 2. Once it has formed an address, the 6LN (re)registers its address
periodically, within the Lifetime of the previous Address periodically, within the Lifetime of the previous Address
Registration, as prescribed by [RFC6775] and [RFC8505], to Registration, as prescribed by [RFC6775] and [RFC8505], to
refresh the NCE before the lifetime indicated in the EARO refresh the NCE before the lifetime indicated in the EARO
expires. The TID is incremented each time and wraps in a expires. The TID is incremented each time and wraps in a
lollipop fashion (see section 5.2.1 of [RFC8505] which is fully lollipop fashion (see section 5.2.1 of [RFC8505] which is fully
compatible with section 7.2 of [RFC6550]). compatible with section 7.2 of [RFC6550]).
3. As stated in section 5.2 of [RFC8505], the 6LN can register to 3. As stated in section 5.2 of [RFC8505], the 6LN can register to
more than one 6LR at the same time. In that case, it MUST use more than one 6LR at the same time. In that case, it uses the
the same value of TID for all of the parallel Address same EARO for all of the parallel Address Registrations. The 6LN
Registrations. The 6LN should send the registration(s) with a SHOULD send the registration(s) that have a non-zero Registration
non-zero Registration Lifetime and ensure that one succeeds Lifetime and ensure that one succeeds before it terminates other
before it terminates other registrations to maintain the state in registrations, to maintain the state in the network and at the
the network and at the 6LBR and minimize the churn. 6LBR and minimize the churn.
4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets 4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets
the "R" flag in the EARO of at least one registration, whereas the "R" flag in the EARO of at least one registration, whereas
acting as an RAN it never does. If the "R" flag is not echoed in acting as an RAN it never does. If the "R" flag is not echoed in
the NA, the RUL SHOULD attempt to use another 6LR. The 6LN the NA, the RUL SHOULD attempt to use another 6LR. The RUL
should send the registration(s) with the "R" flag set and ensure SHOULD send the registration(s) with the "R" flag set and ensure
that one succeeds before it sends the registrations with the flag that one succeeds before it sends the registrations with the flag
reset. In case of a conflict with the preceeding rule on reset. In case of a conflict with the preceeding rule on
lifetime, the rule on lifetime has precedence. lifetime, the rule on lifetime has precedence.
5. The 6LN may use any of the 6LRs to which it registered as default 5. The 6LN may use any of the 6LRs to which it registered as default
gateway. Using a 6LR to which the 6LN is not registered may gateway. Using a 6LR to which the 6LN is not registered may
result in packets dropped at the 6LR by a Source Address result in packets dropped at the 6LR by a Source Address
Validation function (SAVI) so it is not recommended. Validation function (SAVI) so it is NOT RECOMMENDED.
Even without support for RPL, a RUL may be aware of opaque values to Even without support for RPL, a RUL may be aware of opaque values to
be provided to the routing protocol. If the RUL has a knowledge of be provided to the routing protocol. If the RUL has a knowledge of
the RPL Instance the packet should be injected into, then it SHOULD the RPL Instance the packet should be injected into, then it SHOULD
set the Opaque field in the EARO to the RPLInstanceID, else it MUST set the Opaque field in the EARO to the RPLInstanceID, else it MUST
leave the Opaque field to zero. leave the Opaque field to zero.
Regardless of the setting of the Opaque field, the 6LN MUST set the Regardless of the setting of the Opaque field, the 6LN MUST set the
"I" field to zero to signal "topological information to be passed to "I" field to zero to signal "topological information to be passed to
a routing process" as specified in section 5.1 of [RFC8505]. a routing process" as specified in section 5.1 of [RFC8505].
A RUL is not expected to produce RPL artifacts in the data packets, A RUL is not expected to produce RPL artifacts in the data packets,
but it MAY do so. For instance, if the RUL has a minimal awareness but it MAY do so. For instance, if the RUL has a minimal awareness
of the RPL Instance then it can build an RPI. A RUL that places an of the RPL Instance then it can build an RPI. A RUL that places an
RPI in a data packet MUST indicate the RPLInstanceID of the RPL RPI in a data packet MUST indicate the RPLInstanceID of the RPL
Instance where the packet should be forwarded. All the flags and the Instance where the packet should be forwarded. All the flags and the
Rank field are set to zero as specified by section 11.2 of [RFC6550]. Rank field are set to zero as specified by section 11.2 of [RFC6550].
9.2.2. Perspective of the RPL Border Router Acting as 6LR 10.2.2. Perspective of the Border Router Acting as 6LR
Also as prescribed by [RFC8505], the 6LR generates an EDAR message Also as prescribed by [RFC8505], the 6LR generates an EDAR message
upon reception of a valid NS(EARO) message for the registration of a upon reception of a valid NS(EARO) message for the registration of a
new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange
succeeds, then the 6LR installs an NCE for the Registration Lifetime. succeeds, then the 6LR installs an NCE for the Registration Lifetime.
For the refreshes of the registration, if the RPL Root has indicated For the refreshes of the registration, if the RPL Root has indicated
that it proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see that it proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see
Section 4), the 6LR MUST refrain from sending the keep-alive EDAR Section 4), the 6LR MUST refrain from sending the keep-alive EDAR.
itself.
If the "R" flag is set in the NS(EARO), the 6LR SHOULD attempt to If the "R" flag is set in the NS(EARO), the 6LR SHOULD attempt to
inject the host route in RPL, unless this is barred for other inject the host route in RPL, unless this is barred for other
reasons, like a saturation of the network or if its RPL parent. The reasons, like a saturation of the network or if its RPL parent. The
6LR MUST use a RPL Non-Storing Mode signaling. 6LR MUST use a RPL Non-Storing Mode signaling. The 6LR MUST request
a DAO-ACK by setting the 'K' flag in the DAO message. Success
The 6LR SHOULD request a DAO-ACK, failure to do so may incur an injecting the route to the RUL is indicated by the 'E' flag set to 0
asynchronous error flow that will tear down a state just installed in the RPL status of the DAO-ACK message.
with the RUL. The 6LR MUST set "R" flag in the NA(EARO) back if and
only if it injected the Registered Address in the RPL routing. If a
DAO-ACK was requested, this is done upon receiving the DAO-ACK from
the Root with a positive status.
The 6LR may at any time send a unicast asynchronous NA(EARO) with the
"R" flag reset to signal that it stops providing routing services,
and/or with the EARO Status 2 "Neighbor Cache full" to signal that it
removes the NCE. It may also send a final RA, unicast or multicast,
with a Router Lifetime field of zero, to signal that it stops serving
as router, as specified in section 6.2.5 of [RFC4861].
The Opaque field in the EARO hints the 6LR on the RPL Instance that The Opaque field in the EARO hints the 6LR on the RPL Instance that
SHOULD be used for the DAO advertisements, and for the forwarding of SHOULD be used for the DAO advertisements, and for the forwarding of
packets sourced at the registered address when there is no RPI in the packets sourced at the registered address when there is no RPI in the
packet, in which case the 6LR MUST encapsulate the packet to the Root packet, in which case the 6LR MUST encapsulate the packet to the Root
adding an RPI in the outer header. If the Opaque field is zero, the adding an RPI in the outer header. If the Opaque field is zero, the
6LR is free to use the default RPL Instance (zero) for the registered 6LR is free to use the default RPL Instance (zero) for the registered
address or to select an Instance of its choice. address or to select an Instance of its choice.
if the "I" field is not zero, then the 6LR MUST consider that the if the "I" field is not zero, then the 6LR MUST consider that the
Opaque field is zero. If the Opaque field is not zero, then it is Opaque field is zero. If the Opaque field is not zero, then it is
expected to carry a RPLInstanceID for the RPL Instance suggested by expected to carry a RPLInstanceID for the RPL Instance suggested by
the 6LN. If the 6LR does not participate to the associated Instance, the 6LN. If the 6LR does not participate to the associated Instance,
then the 6LR MUST consider that the Opaque field is zero; else, that then the 6LR MUST consider that the Opaque field is zero; else, that
is if the 6LR participates to the suggested Instance, then the 6LR is if the 6LR participates to the suggested RPL Instance, then the
SHOULD use that Instance for the registered address. 6LR SHOULD use that Instance for the Registered Address.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is signaled as Target Prefix in the RPL 1. The Registered Address is signaled as Target Prefix in the RPL
Target Option in the DAO message; the Prefix Length is set to 128 Target Option in the DAO message; the Prefix Length is set to 128
2. RPL Non-Storing Mode is to be used. The 6LR indicates one of its 2. The 6LR indicates one of its global or unique-local IPv6 unicast
global or unique-local IPv6 unicast addresses as the Parent addresses as the Parent Address in the RPL Transit Information
Address in the associated RPL Transit Information Option (TIO) Option (TIO) associated with the Target Option
3. the External 'E' flag in the TIO is set to indicate that the 6LR 3. The 6LR sets the External 'E' flag in the TIO to indicate that it
redistributes an external target into the RPL network redistributes an external target into the RPL network
4. the Path Lifetime in the TIO is computed from the Lifetime in the 4. the Path Lifetime in the TIO is computed from the Lifetime in the
EARO Option. This adapts it to the Lifetime Units used in the EARO Option. This adapts it to the Lifetime Units used in the
RPL operation; note that if the lifetime is 0, then the 6LR RPL operation; note that if the lifetime is 0, then the DAO
generates a No-Path DAO message that cleans up the routes down to message is a No-Path DAO that cleans up the the routes down to
the Address of the 6LN; this also causes the Root as a proxy to the RUL; this also causes the Root as a proxy to send an EDAR
send an EDAR message to the 6LBR with a Lifetime of 0. message to the 6LBR with a Lifetime of 0.
5. the Path Sequence in the TIO is set to the TID value found in the 5. the Path Sequence in the TIO is set to the TID value found in the
EARO option. EARO option.
The NCE is removed if the 6LR tries to inject the route is RPL and Upon receiving the DAO-ACK or an asynchronous DCO message, the 6LR
fails for reasons related to ND, which is recognized by both the 'E' MUST send the NA(EARO) to the RUL.
and the 'A' flags set in the RPL Status of the DAO-ACK or the DCO, as
detailed below.
Otherwise, success injecting the route is assumed if a DAO-ACK was The 6LR MUST set "R" flag in the NA(EARO) back if and only if the 'E'
not requested or if it is received with a RPL Status that is not a flag is reset, indicating that the 6LR injected the Registered
rejection (i.e., the 'E' flag not set). Address in the RPL routing successfully and that the EDAR proxy
operation succeeded.
In case of success, if the 'A' flag is set in the RPL Status of the If the 'A' flag in the RPL Status is set, the embedded Status Value
DAO-ACK, then the 6LR MUST use the Status Value in the RPL Status for is passed back to the RUL in the EARO Status. If the 'E' flags is
the Status in the NA(EARO), else a Status of 0 (Success) is returned. also set, the registration failed for 6LoWPAN ND related reasons, and
the NCE is removed.
The status of 0 MUST also be used if the 6LR could not even try to If the 'A' flag is not set in the RPL Status of the DAO-ACK, then the
inject the route - note that the "R" flag is reset in that case. 6LoWPAN ND operation succeeded and an EARO Status of 0 (Success) MUST
be returned to the RUL, even if the 'E' flag is set in the RPL
Status. The EARO Status of 0 MUST also be used if the 6LR could not
even try to inject the route.
This means that, in case of an error injecting the route that is not
related to ND, the registration succeeds but the RPL route is not
installed, which is signaled by the "R" flag reset. It is up to the
6LN to keep the binding with the 6LR or destroy it.
In a network where Address Protected Neighbor Discovery (AP-ND) is In a network where Address Protected Neighbor Discovery (AP-ND) is
enabled, in case of a DAO-ACK or a DCO indicating transporting an enabled, in case of a DAO-ACK or a DCO indicating transporting an
EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge
the 6LN for ownership of the address, as described in section 6.1 of the 6LN for ownership of the address, as described in section 6.1 of
[AP-ND], before the Registration is complete. This ensures that the [AP-ND], before the Registration is complete. This ensures that the
address validated before it is injected in RPL. address is validated before it is injected in the RPL routing.
If the challenge succeeds then the operations continue as normal. In If the challenge succeeds then the operations continue as normal. In
particular a DAO message is generated upon the NS(EARO) that proves particular a DAO message is generated upon the NS(EARO) that proves
the ownership of the address. If the challenge failed, the 6LR the ownership of the address. If the challenge failed, the 6LR
rejects the registration as prescribed by AP-ND and may take actions rejects the registration as prescribed by AP-ND and may take actions
to protect itself against DoS attacks by a rogue 6LN, see Section 11. to protect itself against DoS attacks by a rogue 6LN, see Section 12.
The other rejection codes indicate that the 6LR failed to inject the The 6LR may at any time send a unicast asynchronous NA(EARO) with the
address into the RPL network. If an EARO Status is transported, the "R" flag reset to signal that it stops providing routing services,
6LR MUST send a NA(EARO) to the RUL with that Status value, and the and/or with the EARO Status 2 "Neighbor Cache full" to signal that it
"R" flag not set. Similarly, upon receiving a DCO message indicating removes the NCE. It may also send a final RA, unicast or multicast,
that the address of a RUL should be removed from the routing table, with a Router Lifetime field of zero, to signal that it stops serving
the 6LR issues an asynchronous NA(EARO) to the RUL with the embedded as router, as specified in section 6.2.5 of [RFC4861].
ND Status value if there was one, and the "R" flag not set.
If a 6LR receives a valid NS(EARO) message with the "R" flag reset If a 6LR receives a valid NS(EARO) message with the "R" flag reset
and a Registration Lifetime that is not 0, and the 6LR was and a Registration Lifetime that is not 0, and the 6LR was injecting
redistributing the Registered Address due to previous NS(EARO) the Registered Address due to previous NS(EARO) messages with the "R"
messages with the flag set, then it MUST stop injecting the address. flag set, then the 6LR MUST stop injecting the address. It is up to
It is up to the Registering 6LN to maintain the corresponding route the Registering 6LN to maintain the corresponding route from then on,
from then on, either keeping it active via a different 6LR or by either keeping it active via a different 6LR or by acting as an RAN
acting as an RAN and managing its own reachability. and managing its own reachability.
9.2.3. Perspective of the RPL Root 10.2.3. Perspective of the RPL Root
A RPL Root SHOULD set the "P" flag in the RPL configuration option of A RPL Root SHOULD set the "P" flag in the RPL configuration option of
the DIO messages that it generates (see Section 4) to signal that it the DIO messages that it generates (see Section 4) to signal that it
proxies the keep-alive EDAR/EDAC exchange and supports the Updated proxies the EDAR/EDAC exchange and supports the Updated RPL Target
RPL Target option. The remainder of this section assumes that it option. The remainder of this section assumes that it does.
does.
Upon reception of a DAO message, for each RPL Target option that Upon reception of a DAO message, for each RPL Target Option that
creates or updates an existing RPL state, the Root MUST notify the creates or updates an existing RPL state, the Root MUST notify the
6LBR. This can be done using an internal API if they are co-located, 6LBR. This can be done using an internal API if they are integrated,
or using a proxied EDAR/EDAC exchange if they are separated. or using a proxied EDAR/EDAC exchange if they are separate entities.
Upon receiving an EDAC message from the 6LBR, if a DAO is pending, Upon receiving an EDAC message from the 6LBR, if a DAO is pending,
then the Root MUST send a DAO-ACK back to the 6LR. Else, if the then the Root MUST send a DAO-ACK back to the 6LR. Else, if the
Status in the EDAC message is not "Success", then it MUST send an Status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. In either case, the EDAC Status is asynchronous DCO to the 6LR.
embedded in the RPL Status with the 'A' flag set.
In either case, the EDAC Status is embedded in the RPL Status with
the 'A' flag set.
The EDAR message MUST be constructed as follows: The EDAR message MUST be constructed as follows:
1. The Target IPv6 address from the RPL Target Option is placed in 1. The Target IPv6 address from the RPL Target Option is placed in
the Registered Address field of the EDAR message; the Registered Address field of the EDAR message;
2. the Registration Lifetime is adapted from the Path Lifetime in 2. the Registration Lifetime is adapted from the Path Lifetime in
the TIO by converting the Lifetime Units used in RPL into units the TIO by converting the Lifetime Units used in RPL into units
of 60 seconds used in the 6LoWPAN ND messages; of 60 seconds used in the 6LoWPAN ND messages;
3. the TID value is set to the Path Sequence in the TIO and 3. the TID value is set to the Path Sequence in the TIO and
indicated with an ICMP code of 1 in the EDAR message; indicated with an ICMP code of 1 in the EDAR message;
4. If the ROVR is present in the RPL Target option, it is copied as 4. The ROVR in the RPL Target Option is copied as is in the EDAR and
is in the EDAR and the ICMP Code Suffix is set to the appropriate the ICMP Code Suffix is set to the appropriate value as shown in
value as shown in Table 4 of [RFC8505] depending on the size of Table 4 of [RFC8505] depending on the size of the ROVR field.
the ROVR field; else, the ROVR field in the EDAR is set to zero
indicating an anonymous EDAR.
9.2.4. Perspective of the 6LBR
Upon reception of an EDAR message with the ROVR field set to a non-
zero value, the 6LBR acts as prescribed by [RFC8505] and returns an
EDAC message to the sender.
If the ROVR is set to 0, indicating an anonymous EDAR, the 6LBR MUST
act as below:
1. The 6LBR checks whether an entry exists for the address. If the
entry does not exist, the 6LBR MUST NOT create the entry, and it
MUST answer with a Status "Removed" in the EDAC message. If the
entry exists, the 6LBR computes whether the TID in the EDAR
message is fresher than the one in the entry as prescribed in
section 4.2.1 of [RFC8505], and continues as follows:
2. If the anonymous EDAR message is fresher, the 6LBR updates the 10.2.4. Perspective of the 6LBR
TID in the entry, restarts the heartbeat timer for the entry, and
answers with a Status "Success" in the EDAC message. If the
value of the Registration Lifetime is smaller than the value in
the entry, then the latter value MUST be used for the heartbeat;
this means in particular that the Registration Lifetime of 0 is
ignored. Conversely, if the duration of the Lifetime is extended
by the Registration Lifetime in the EDAR message, it is used for
the hearbeat and to the value in the entry is updated.
3. If the TID in the entry is the same or fresher, the 6LBR does not The 6LBR is unaware that the RPL Root is not the new attachment 6LR
update the entry, and answers with a Status "Success" and "Moved" of the RUL, so it is not impacted by this specification.
in the EDAC message, respectively.
The EDAC that is constructed is the same as if the anonymous EDAR was Upon reception of an EDAR message, the 6LBR acts as prescribed by
a full EDAR, but for the ROVR that is set to zero. [RFC8505] and returns an EDAC message to the sender.
10. Protocol Operations for Multicast Addresses 11. Protocol Operations for Multicast Addresses
Section 12 of [RFC6550] details the RPL support for multicast flows. Section 12 of [RFC6550] details the RPL support for multicast flows.
This support is not source-specific and only operates as an extension This support is not source-specific and only operates as an extension
to the Storing Mode of Operation for unicast packets. Note that it to the Storing Mode of Operation for unicast packets. Note that it
is the RPL model that the multicast packet is passed as a Layer-2 is the RPL model that the multicast packet is passed as a Layer-2
unicast to each of the interested children. This remains true when unicast to each of the interested children. This remains true when
forwarding between the 6LR and the listener 6LN. forwarding between the 6LR and the listener 6LN.
"Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its "Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its
updated version "Multicast Listener Discovery Version 2 (MLDv2) for updated version "Multicast Listener Discovery Version 2 (MLDv2) for
IPv6" [RFC3810] provide an interface for a listener to register to IPv6" [RFC3810] provide an interface for a listener to register to
multicast flows. MLDv2 is backwards compatible with MLD, and adds in multicast flows. MLDv2 is backwards compatible with MLD, and adds in
particular the capability to filter the sources via black lists and particular the capability to filter the sources via black lists and
white lists. In the MLD model, the Router is a "querier" and the white lists. In the MLD model, the Router is a "querier" and the
Host is a multicast listener that registers to the querier to obtain Host is a multicast listener that registers to the querier to obtain
copies of the particular flows it is interested in. copies of the particular flows it is interested in.
On the first Address Registration, as illustrated in Figure 9, the On the first Address Registration, as illustrated in Figure 8, the
6LN, as an MLD listener, sends an unsolicited Report to the 6LR in 6LN, as an MLD listener, sends an unsolicited Report to the 6LR in
order to start receiving the flow immediately. order to start receiving the flow immediately.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| unsolicited Report | | | | unsolicited Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | | | <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | <if not listening> | | | | <if not listening> |
| | | unsolicited Report | | | | unsolicited Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
Figure 9: First Multicast Registration Flow Figure 8: First Multicast Registration Flow
Since multicast Layer-2 messages are avoided, it is important that Since multicast Layer-2 messages are avoided, it is important that
the asynchronous messages for unsolicited Report and Done are sent the asynchronous messages for unsolicited Report and Done are sent
reliably, for instance using a Layer-2 acknowledgment, or attempted reliably, for instance using a Layer-2 acknowledgment, or attempted
multiple times. multiple times.
The 6LR acts as a generic MLD querier and generates a DAO for the The 6LR acts as a generic MLD querier and generates a DAO for the
multicast target. The lifetime of the DAO is set to be in the order multicast target. The lifetime of the DAO is set to be in the order
of the Query Interval, yet larger to account for variable propagation of the Query Interval, yet larger to account for variable propagation
delays. delays.
The Root proxies the MLD exchange as a listener with the 6LBR acting The Root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the as the querier, so as to get packets from a source external to the
RPL domain. Upon a DAO with a multicast target, the RPL Root checks RPL domain.
if it is already registered as a listener for that address, and if
not, it performs its own unsolicited Report for the multicast target. Upon a DAO with a multicast target, the RPL Root checks if it is
already registered as a listener for that address, and if not, it
performs its own unsolicited Report for the multicast target.
An Address re-Registration is pulled periodically by 6LR acting as An Address re-Registration is pulled periodically by 6LR acting as
querier. Note that the message may be sent unicast to all the known querier. Note that the message may be sent unicast to all the known
individual listeners. Upon a time out of the Query Interval, the 6LR individual listeners.
sends a Query to each of its listeners, and gets a Report back that
is mapped into a DAO, as illustrated in Figure 10: Upon the timing out of the Query Interval, the 6LR sends a Query to
each of its listeners, and gets a Report back that is mapped into a
DAO, as illustrated in Figure 9:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | | | <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | | | | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 10: Next Registration Flow Figure 9: Next Registration Flow
Note that any of the functions 6LR, Root and 6LBR might be collapsed Note that any of the functions 6LR, Root and 6LBR might be collapsed
in a single node, in which case the flow above happens internally, in a single node, in which case the flow above happens internally,
and possibly through internal API calls as opposed to messaging. and possibly through internal API calls as opposed to messaging.
11. Security Considerations 12. Security Considerations
First of all, it is worth noting that with [RFC6550], every node in First of all, it is worth noting that with [RFC6550], every node in
the LLN is RPL-aware and can inject any RPL-based attack in the the LLN is RPL-aware and can inject any RPL-based attack in the
network. This specification isolates edge nodes that can only network. This specification isolates edge nodes that can only
interact with the RPL routers using 6LoWPAN ND, meaning that they interact with the RPL routers using 6LoWPAN ND, meaning that they
cannot perform RPL insider attacks. cannot perform RPL insider attacks.
6LoWPAN ND can optionally provide SAVI features with [AP-ND], which 6LoWPAN ND can optionally provide SAVI features with [AP-ND], which
reduces even more the attack perimeter that is available to the edge reduces even more the attack perimeter that is available to the edge
nodes. nodes.
skipping to change at page 26, line 32 skipping to change at page 25, line 24
"Removed" Status code. "Removed" Status code.
This trust model could be at a minimum based on a Layer-2 Secure This trust model could be at a minimum based on a Layer-2 Secure
joining and the Link-Layer security. This is a generic 6LoWPAN joining and the Link-Layer security. This is a generic 6LoWPAN
requirement, see Req5.1 in Appendix of [RFC8505]. requirement, see Req5.1 in Appendix of [RFC8505].
Additionally, the trust model could include a role validation to Additionally, the trust model could include a role validation to
ensure that the node that claims to be a 6LBR or a RPL Root is ensure that the node that claims to be a 6LBR or a RPL Root is
entitled to do so. entitled to do so.
The anonymous EDAR message does not carry a valid Registration Unique
ID [RFC8505] in the form of a ROVR and may be played by any node on
the network without the need to know the ROVR. The 6LBR MUST NOT
create an entry based on a anonymous EDAR and it MUST NOT decrease
the value of the lifetime. All it can do is refresh the lifetime and
the TID of an existing entry. So the message cannot be used to
create a binding state in the 6LBR but it can be used to maintain one
active longer than expected.
Note that a full EDAR message with a lifetime of 0 will destroy that
state and the anonymous message will not recreate it. Note also that
a rogue that has access to the network can attack the 6LBR with other
(forged) addresses and ROVR, and that this is a much easier DoS
attack than trying to keep existing state alive longer.
At the time of this writing RPL does not have a zerotrust model At the time of this writing RPL does not have a zerotrust model
whereby it is possible to validate the origin of an address that is whereby it is possible to validate the origin of an address that is
injected in a DAO. This specification makes a first step in that injected in a DAO. This specification makes a first step in that
direction by allowing the Root to challenge the RUL by the 6LR that direction by allowing the Root to challenge the RUL via the 6LR that
serves it. serves it.
12. IANA Considerations 13. IANA Considerations
12.1. Resizing the ARO Status values 13.1. Resizing the ARO Status values
Section 12 of [RFC6775] creates the Address Registration Option Section 12 of [RFC6775] creates the Address Registration Option
Status Values Registry with a range 0-255. This specification Status Values Registry with a range 0-255. This specification
reduces that range to 0-63. reduces that range to 0-63.
IANA is requested to reduce the unassigned values range from 11-255 IANA is requested to reduce the unassigned values range from 11-255
to 11-63. to 11-63.
12.1.1. RPL Target Option Flags 13.2. New DODAG Configuration Option Flag
Section 20.15 of [RFC6550] creates a Registry for the 8-bit RPL
Target Option Flags field.
IANA is requested to reduce the size of the field in the Registry to
4 bits.
12.1.2. Address Registration Option Flags
Section 9.1 of [RFC8505] creates a Registry for the 8-bit Address
Registration Option Flags field.
IANA is requested to rename the first column of the table from "ARO
Status" to "Bit number".
12.2. New DODAG Configuration Option Flag
This specification updates the Registry for the "DODAG Configuration This specification updates the Registry for the "DODAG Configuration
Option Flags" that was created for [RFC6550] as follows: Option Flags" that was created for [RFC6550] as follows:
+------------+----------------------------+-----------+ +------------+----------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+============+============================+===========+ +============+============================+===========+
| 1 | Root Proxies EDAR/EDAC (P) | THIS RFC | | 1 | Root Proxies EDAR/EDAC (P) | THIS RFC |
+------------+----------------------------+-----------+ +------------+----------------------------+-----------+
Table 2: New DODAG Configuration Option Flag Table 2: New DODAG Configuration Option Flag
12.3. New Subregistry for the RPL Non-Rejection Status values 13.3. New RPL Target Option Flag
Section 20.15 of [RFC6550] creates a Registry for the 8-bit "RPL
Target Option Flags" field. IANA is requested to reduce the size of
the field in the Registry to 4 bits. This specification also defines
a new entry in the Registry as follows:
+------------+--------------------------------+-----------+
| Bit Number | Capability Description | Reference |
+============+================================+===========+
| 1 | Advertiser Address in Full (F) | THIS RFC |
+------------+--------------------------------+-----------+
Table 3: New RPL Target Option Flag
13.4. New Subregistry for the RPL Non-Rejection Status values
This specification creates a new Subregistry for the RPL Non- This specification creates a new Subregistry for the RPL Non-
Rejection Status values for use in RPL DAO-ACK and DCO messages with Rejection Status values for use in RPL DAO-ACK and DCO messages with
the 'A' flag reset, under the ICMPv6 parameters registry. the 'A' flag reset, under the ICMPv6 parameters registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 3: * Initial allocation is as indicated in Table 4:
+-------+------------------------+-----------+ +-------+------------------------+-----------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+========================+===========+ +=======+========================+===========+
| 0 | Unqualified acceptance | RFC 6550 | | 0 | Unqualified acceptance | RFC 6550 |
+-------+------------------------+-----------+ +-------+------------------------+-----------+
Table 3: Acceptance values of the RPL Status Table 4: Acceptance values of the RPL Status
12.4. New Subregistry for the RPL Rejection Status values 13.5. New Subregistry for the RPL Rejection Status values
This specification creates a new Subregistry for the RPL Rejection This specification creates a new Subregistry for the RPL Rejection
Status values for use in RPL DAO-ACK and RCO messages with the 'A' Status values for use in RPL DAO-ACK and RCO messages with the 'A'
flag reset, under the ICMPv6 parameters registry. flag reset, under the ICMPv6 parameters registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 4: * Initial allocation is as indicated in Table 5:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+=======================+===============+ +=======+=======================+===============+
| 0 | Unqualified rejection | This document | | 0 | Unqualified rejection | This document |
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
Table 4: Rejection values of the RPL Status Table 5: Rejection values of the RPL Status
13. Acknowledgments 13.6. Fixing the Address Registration Option Flags
Section 9.1 of [RFC8505] creates a Registry for the 8-bit Address
Registration Option Flags field.
IANA is requested to rename the first column of the table from "ARO
Status" to "Bit number".
14. Acknowledgments
The authors wish to thank Ines Robles, Georgios Papadopoulos and The authors wish to thank Ines Robles, Georgios Papadopoulos and
Rahul Jadhav for their reviews and contributions to this document. Rahul Jadhav for their reviews and contributions to this document.
14. Normative References 15. Normative References
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, Listener Discovery (MLD) for IPv6", RFC 2710,
DOI 10.17487/RFC2710, October 1999, DOI 10.17487/RFC2710, October 1999,
<https://www.rfc-editor.org/info/rfc2710>. <https://www.rfc-editor.org/info/rfc2710>.
skipping to change at page 31, line 16 skipping to change at page 29, line 46
23 March 2020, <https://tools.ietf.org/html/draft-ietf- 23 March 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-38>. roll-useofrplinfo-38>.
[EFFICIENT-NPDAO] [EFFICIENT-NPDAO]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", Work in Progress, Internet-Draft, Route Invalidation", Work in Progress, Internet-Draft,
draft-ietf-roll-efficient-npdao-18, 15 April 2020, draft-ietf-roll-efficient-npdao-18, 15 April 2020,
<https://tools.ietf.org/html/draft-ietf-roll-efficient- <https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-18>. npdao-18>.
15. Informative References 16. Informative References
[RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem
Statement and Requirements for IPv6 over Low-Power Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing", Wireless Personal Area Network (6LoWPAN) Routing",
RFC 6606, DOI 10.17487/RFC6606, May 2012, RFC 6606, DOI 10.17487/RFC6606, May 2012,
<https://www.rfc-editor.org/info/rfc6606>. <https://www.rfc-editor.org/info/rfc6606>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
skipping to change at page 32, line 17 skipping to change at page 30, line 44
January 2019, <https://www.rfc-editor.org/info/rfc8504>. January 2019, <https://www.rfc-editor.org/info/rfc8504>.
[6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 [6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", Work in Progress, Internet-Draft, draft- Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-20, 23 March 2020, ietf-6lo-backbone-router-20, 23 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-backbone- <https://tools.ietf.org/html/draft-ietf-6lo-backbone-
router-20>. router-20>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 11 illustrates the case in Storing Mode where the packet is Figure 10 illustrates the case in Storing Mode where the packet is
received from the Internet, then the Root encapsulates the packet to received from the Internet, then the Root encapsulates the packet to
insert the RPI and deliver to the 6LR that is the parent and last hop insert the RPI and deliver to the 6LR that is the parent and last hop
to the final destination, which is not known to support [RFC8138]. to the final destination, which is not known to support [RFC8138].
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4 bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
<- No RPL artifact ... <- No RPL artifact ...
Figure 11: Encapsulation to Parent 6LR in Storing Mode Figure 10: Encapsulation to Parent 6LR in Storing Mode
The difference with the example presented in Figure 19 of [RFC8138] The difference with the example presented in Figure 19 of [RFC8138]
is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
compressed address of the 6LR as the destination address of the outer compressed address of the 6LR as the destination address of the outer
IPv6 header. In the original example the destination IP of the outer IPv6 header. In the original example the destination IP of the outer
header was elided and was implicitly the same address as the header was elided and was implicitly the same address as the
destination of the inner header. Type 1 was arbitrarily chosen, and destination of the inner header. Type 1 was arbitrarily chosen, and
the size of 0 denotes a single address in the SRH. the size of 0 denotes a single address in the SRH.
In Figure 11, the source of the IP-in-IP encapsulation is the Root, In Figure 10, the source of the IP-in-IP encapsulation is the Root,
so it is elided in the IP-in-IP 6LoRH. The destination is the parent so it is elided in the IP-in-IP 6LoRH. The destination is the parent
6LR of the destination of the inner packet so it cannot be elided. 6LR of the destination of the inner packet so it cannot be elided.
If the DODAG is operated in Storing Mode, it is the single entry in If the DODAG is operated in Storing Mode, it is the single entry in
the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH
is the first 6LoRH in the chain. In this particular example, the 6LR is the first 6LoRH in the chain. In this particular example, the 6LR
address can be compressed to 2 bytes so a Type of 1 is used. It address can be compressed to 2 bytes so a Type of 1 is used. It
results that the total length of the SRH-6LoRH is 4 bytes. results that the total length of the SRH-6LoRH is 4 bytes.
In Non-Storing Mode, the encapsulation from the Root would be similar In Non-Storing Mode, the encapsulation from the Root would be similar
to that represented in Figure 11 with possibly more hops in the SRH- to that represented in Figure 10 with possibly more hops in the SRH-
6LoRH and possibly multiple SRH-6LoRHs if the various addresses in 6LoRH and possibly multiple SRH-6LoRHs if the various addresses in
the routing header are not compressed to the same format. Note that the routing header are not compressed to the same format. Note that
on the last hop to the parent 6LR, the RH3 is consumed and removed on the last hop to the parent 6LR, the RH3 is consumed and removed
from the compressed form, so the use of Non-Storing Mode vs. Storing from the compressed form, so the use of Non-Storing Mode vs. Storing
Mode is indistinguishable from the packet format. Mode is indistinguishable from the packet format.
The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH. The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH.
When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that
precede it are also removed. The Paging Dispatch [RFC8025] may also precede it are also removed. The Paging Dispatch [RFC8025] may also
be removed if there was no previous Page change to a Page other than be removed if there was no previous Page change to a Page other than
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