draft-ietf-roll-unaware-leaves-09.txt   draft-ietf-roll-unaware-leaves-10.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: 6550, 8505 (if approved) M. Richardson
Intended status: Standards Track Sandelman Intended status: Standards Track Sandelman
Expires: 30 July 2020 27 January 2020 Expires: 13 September 2020 12 March 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-09 draft-ietf-roll-unaware-leaves-10
Abstract Abstract
This specification extends RFC6550 and RFC8505 to provide unicast and This specification extends RFC6550 and RFC8505 to provide unicast and
multicast routing services in a RPL domain to 6LNs that are plain multicast routing services in a RPL domain to 6LNs that are plain
Hosts and do not participate to RPL, and enables the RPL Root to Hosts and do not participate to RPL, and enables the RPL Root to
proxy the EDAR/EDAC flow on behalf of the RULs and RANs in its DODAG. proxy the EDAR/EDAC flow on behalf of the RULs and RANs 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 30 July 2020. This Internet-Draft will expire on 13 September 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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provided without warranty as described in the Simplified BSD License. provided without warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 7 3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 7
3.1. RFC 6775 . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 7
3.2. RFC 8505 Extended ARO . . . . . . . . . . . . . . . . . . 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 RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 11
6. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11 6. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11
6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11 6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11
6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12 6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12
6.2.1. Support of the HbH Header . . . . . . . . . . . . . . 13 6.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13
6.2.2. Support of the Routing Header . . . . . . . . . . . . 13 6.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13
6.2.3. Support of IPv6 Encapsulation . . . . . . . . . . . . 13 6.2.3. Support of the Routing Header . . . . . . . . . . . . 13
7. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13 7. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13
8. Updated RPL Target option . . . . . . . . . . . . . . . . . . 14 8. Updated RPL Target option . . . . . . . . . . . . . . . . . . 14
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 15 9. Protocol Operations for Unicast Addresses . . . . . . . . . . 15
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 15 9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 15
9.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 16 9.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 16
9.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 19 9.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 18
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19 9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19
9.2.1. By the 6LN . . . . . . . . . . . . . . . . . . . . . 20 9.2.1. By the 6LN . . . . . . . . . . . . . . . . . . . . . 19
9.2.2. By the 6LR . . . . . . . . . . . . . . . . . . . . . 21 9.2.2. By the 6LR . . . . . . . . . . . . . . . . . . . . . 20
9.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 23 9.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 22
9.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 24 9.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 23
10. Protocol Operations for Multicast Addresses . . . . . . . . . 24 10. Protocol Operations for Multicast Addresses . . . . . . . . . 24
11. Security Considerations . . . . . . . . . . . . . . . . . . . 26 11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
12.1. New DODAG Configuration Option Flag . . . . . . . . . . 27 12.1. Resizing the ARO Status values . . . . . . . . . . . . . 26
12.2. RPL Target Option Flags . . . . . . . . . . . . . . . . 27 12.2. New DODAG Configuration Option Flag . . . . . . . . . . 26
12.3. New Subregistry for the RPL Non-Rejection Status 12.3. RPL Target Option Flags . . . . . . . . . . . . . . . . 27
12.4. New Subregistry for the RPL Non-Rejection Status
values . . . . . . . . . . . . . . . . . . . . . . . . . 27 values . . . . . . . . . . . . . . . . . . . . . . . . . 27
12.4. New Subregistry for the RPL Rejection Status values . . 27 12.5. New Subregistry for the RPL Rejection Status values . . 27
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28
14. Normative References . . . . . . . . . . . . . . . . . . . . 28 14. Normative References . . . . . . . . . . . . . . . . . . . . 28
15. Informative References . . . . . . . . . . . . . . . . . . . 30 15. Informative References . . . . . . . . . . . . . . . . . . . 30
Appendix A. Example Compression . . . . . . . . . . . . . . . . 31 Appendix A. Example Compression . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
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
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given LLN. This trades the quality of peer-to-peer (P2P) paths for a given LLN. This trades the quality of peer-to-peer (P2P) paths for a
vastly reduced amount of control traffic and routing state that would vastly reduced amount of control traffic and routing state that would
be required to operate a any-to-any shortest path protocol. Finally, be required to operate a any-to-any shortest path protocol. Finally,
broken routes may be fixed lazily and on-demand, based on dataplane broken routes may be fixed lazily and on-demand, based on dataplane
inconsistency discovery, which avoids wasting energy in the proactive inconsistency discovery, which avoids wasting energy in the proactive
repair of unused paths. repair of unused paths.
In order to cope with lossy transmissions, RPL forms Direction- In order to cope with lossy transmissions, 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 Solicitation (DIS) and DODAG Information Object (DIO) messages. For
most 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 routes proactively but only fixes them when lazy control that creates the routes proactively, but may only fix
they are used by actual traffic. them reactively, upon actual traffic. The result is that RPL
provides reachability for most of the LLN nodes, most of the time,
The result is that RPL provides reachability for most of the LLN but may not converge in the classical sense.
nodes, most of the time, but may not really converge in the classical
sense. RPL provides unicast and multicast routing services back to
RPL-Aware nodes (RANs).
A RAN will inject routes to itself using Destination Advertisement [RFC6550] provides unicast and multicast routing services back to
Object (DAO) messages sent to either parent-nodes in Storing Mode or RPL-Aware nodes (RANs), either as a collection tree or with routing
to the Root indicating their parent in Non-Storing Mode. This back. In tha latter case, a RAN injects routes to itself using
process effectively forms a DODAG back to the device that is a subset Destination Advertisement Object (DAO) messages sent to either
of the DODAG to the Root with all links reversed. parent-nodes in the RPL Storing Mode or to the Root indicating their
parent in the Non-Storing Mode. This process effectively forms a
DODAG back to the device that is a subset of the DODAG to the Root
with all links reversed.
RPL can be deployed as an extension to IPv6 Neighbor Discovery (ND) RPL can be deployed as an extension to IPv6 Neighbor Discovery (ND)
[RFC4861][RFC4862] and 6LoWPAN ND [RFC6775][RFC8505] to maintain [RFC4861][RFC4862] and 6LoWPAN ND [RFC6775][RFC8505] to maintain
reachability within a Non-Broadcast Multi-Access (NBMA) subnet. In reachability within a Non-Broadcast Multi-Access (NBMA) subnet. In
that mode, some nodes may act as Routers and participate to the that mode, some nodes may act as Routers and participate to the
forwarding operations whereas others will only terminate packets, forwarding operations whereas others will only terminate packets,
acting as Hosts in the data-plane. In [RFC6550] terms, a Host that acting as Hosts in the data-plane. In [RFC6550] terms, a Host that
is reachable over the RPL network is called a Leaf. is reachable over the RPL network is called a Leaf.
"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, a RPL-Unaware Leaf (RUL) designates a Leaf does not In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf does
participate to RPL at all. A RUL is a plain Host that needs an not participate to RPL at all. A RUL is a plain Host that needs a
interface to its RPL Router to obtain routing services over the LLN. RPL-Aware Router to obtain routing services over the RPL network.
This specification enables a RUL that is a 6LoWPAN Node (6LN) to This specification leverages the Address Registration mechanism
announce itself as a Host to its 6LoWPAN Router (6LR) in the 6LoWPAN defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to
ND Address Address Registration, and to request that the 6LR injects interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) to
the relevant routing information for the Registered Address in the request that the 6LR injects the relevant routing information for the
RPL domain on its behalf. The unicast packet forwarding operation by Registered Address in the RPL domain on its behalf. The unicast
the 6LR serving a 6LN that is a RPL Leaf is described in packet forwarding operation by the 6LR serving a 6LN that is a RPL
[USEofRPLinfo]. Leaf is described in [USEofRPLinfo].
Examples of routing-agnostic 6LN may 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 application of this specification may include light switches. Other application 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 receive control packet from the Smartgrid. can still interact with the Smartgrid for control and/or metering.
2. Terminology 2. Terminology
2.1. BCP 14 2.1. BCP 14
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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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 3.1. RFC 6775 Address Registration
The "IPv6 Neighbor Discovery (IPv6 ND) Protocol" suite [RFC4861] The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861]
[RFC4862] was defined for transit media such a Ethernet, and relies [RFC4862] was defined for transit media such a Ethernet. It is a
heavily on multicast operations for address discovery and duplicate reactive protocol that relies heavily on multicast operations for
address detection (DAD). "Neighbor Discovery Optimizations for address discovery (aka lookup) and duplicate address detection (DAD).
6LoWPAN networks" [RFC6775] (6LoWPAN ND) adapts IPv6 ND for
operations over energy-constrained LLNs. In particular, 6LoWPAN ND
introduces a unicast Host Registration mechanism that contributes to
reducing the use of multicast messages that are present in the
classical IPv6 ND protocol.
6LoWPAN ND defines a new Address Registration Option (ARO) that is "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
adapts IPv6 ND for operations over energy-constrained LLNs. The main
functions of [RFC6775] are to proactively establish the Neighbor
Cache Entry (NCE) in the 6LR and to prevent address duplication. To
that effect, [RFC6775] introduces a new unicast Address Registration
mechanism that contributes to reducing the use of multicast messages
compared to the classical IPv6 ND protocol.
[RFC6775] defines a new Address Registration Option (ARO) that is
carried in the unicast Neighbor Solicitation (NS) and Neighbor carried in the unicast Neighbor Solicitation (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). 6LoWPAN ND also defines the Duplicate Address 6LoWPAN Router (6LR). It also defines the Duplicate Address Request
Request (DAR) and Duplicate Address Confirmation (DAC) messages (DAR) and Duplicate Address Confirmation (DAC) messages between the
between the 6LR and the 6LoWPAN Border Router (6LBR). In an LLN, the 6LR and the 6LoWPAN Border Router (6LBR). In an LLN, the 6LBR is the
6LBR is the central repository of all the Registered Addresses in its central repository of all the Registered Addresses in its domain and
domain. the source of truth for uniqueness and ownership.
The main functions of [RFC6775] are to proactively establish the
Neighbor Cache Entry in the 6LR and to avoid address duplication.
3.2. RFC 8505 Extended ARO 3.2. RFC 8505 Extended Address Registration
"Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505] "Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505]
updates the behavior of RFC 6775 to enable a generic Address updates the behavior of RFC 6775 to enable a generic Address
Registration to services such as routing and ND proxy, and defines Registration to services such as routing and ND proxy, and defines
the Extended Address Registration Option (EARO) as shown in Figure 1: the Extended Address Registration Option (EARO) as shown in Figure 1:
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 | Length | Status | Opaque | | Type | Length | Status | Opaque |
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... Registration Ownership Verifier ... ... Registration Ownership Verifier ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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, e.g., by means of routing or reachability for the Registered Address. If the "R" flag is not set,
proxying ND. If the "R" flag is not set, then the Registering Node then the Registering Node handles the reachability of the Registered
is expected to be a RAN that handles the reachability of the Address by other means, which means in a RPL network that it is a RAN
Registered Address 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 operates as a RUL for an IPv6 address iff it sets the "R" RPL. A 6LN is a RUL that requires reachability services for an IPv6
flag in the EARO used to register the address. The RPL Router address iff it sets the "R" flag in the EARO used to register the
generates a DAO message for the Registered Address upon an NS(EARO) address to a RPL router. Conversely, this document specifies the
iff the "R" flag in the EARO is set. Conversely, this document behavior of a RPL Router acting as 6LR depending on the setting of
specifies the behavior of a RPL Router acting as 6LR that depends on the "R" flag in the EARO. The RPL Router generates a DAO message for
the setting of the "R" flag in the EARO. the Registered Address upon an NS(EARO) iff 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 6.1). The EARO also transports an
Opaque field and an "I" field that describes what the Opaque field Opaque field and an "I" field that describes what the Opaque field
transports and how to use it. Section 9.2.1 specifies the use of the transports and how to use it. Section 9.2.1 specifies the use of the
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"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, which means that nodes DAO to build the proxied EDAR at the Root (see Section 8), which
that are aware of the Host route to the 6LN are now aware of the means that nodes that are aware of the Host route to the 6LN are made
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 periodic DAR/DAC exchange that takes place
between the 6LR and the 6LBR using Extended DAR/DAC messages. The between the 6LR and the 6LBR using Extended DAR/DAC messages which
Extended Duplicate Address messages can carry a ROVR field of can carry a ROVR field of variable size. The periodic EDAR/EDAC
variable size. The periodic EDAR/EDAC exchange is triggered by a exchange is triggered by a NS(EARO) message and is intended to create
NS(EARO) message and is intended to create and then refresh the and then refresh the corresponding state in the 6LBR for a lifetime
corresponding state in the 6LBR for a lifetime that is indicated by that is indicated by the 6LN.
the 6LN. Conversely, 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 a lifetime that is indicated by the source of the
DAO. This means that there are two periodic messages that traverse
the whole network to indicate that an address is still reachable, one
to the Root and one to the 6LBR.
This specification saves the support of RPL in a 6LN called a RUL and Conversely, RPL [RFC6550] specifies a periodic DAO from the 6LN all
avoids an extraneous periodic flow across the LLN. The RUL only the way to the Root that maintains the routing state in the RPL
needs to perform a [RFC8505] Address Registration to the 6LR. The network for the lifetime indicated by the source of the DAO. This
6LR turns it into a DAO message to the Root on behalf of the RUL. means that for each address, there are two keep-alive messages that
Upon the new DAO, the Root proxies the EDAR exchange to the 6LBR on traverse the whole network, one to the Root and one to the 6LBR.
behalf of the 6LR. This is illustrated in Figure 6.
This specification saves the extraneous keep-alive across the LLN.
The 6LR turns the periodic Address Registration from the RUL into a
DAO message to the Root every time, but only generates the EDAR upon
the first registration, for the purpose of DAD. Upon a refresher
DAO, 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.
E: Node is an IPv6 ND Registrar -- i.e., it supports registrations E: Node is an IPv6 ND Registrar -- i.e., it supports registrations
based on EARO. based on EARO.
P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that
also provides reachability services for the Registered Addres also provides reachability services for the Registered Addres
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 | 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 RUL can get reachability services from a 6LR if and only if the L, A 6LR that can provide reachability services for a RUL in a RPL
P and E flags are set in a 6CIO originated by the 6LR. A 6LR that network as specified in this document SHOULD include a 6CIO in its RA
can provide reachability services for a RUL node in a RPL network as messages and set the L, P and E flags as prescribed by [RFC8505], see
specified in this document sets the L, P and E flags. Section 6.1 for the 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 9) and multicast
addresses (see Section 10) on behalf of leaves that are not aware of addresses (see Section 10) on behalf of leaves that are not aware of
RPL. The Targets are exposed as External addresses. An IP-in-IP RPL. The addresses are exposed as external targets [RFC6550]. Per
encapsulation that terminates at the border 6LR is used to remove RPL [USEofRPLinfo], an IP-in-IP encapsulation that terminates at the RPL
artifacts and compression techniques that may not be processed Root is used to remove RPL artifacts and compression techniques that
correctly outside of the RPL domain. may not be processed correctly outside of the RPL domain.
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. A same value of lifetime is used for both, and a
single heartbeat 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 5), for any
6LN, RUL or RAN. 6LN, RUL or RAN.
RPL defines a configuration option that is registered to IANA in RPL defines a configuration option that is registered to IANA in
section 20.14. of [RFC6550]. This specification defines a new flag section 20.14. of [RFC6550]. This specification defines a new flag
"Root Proxies EDAR/EDAC" (P) that is encoded in one of the reserved "Root Proxies EDAR/EDAC" (P) that is encoded in one of the reserved
control bits in the option. The new flag is set to indicate that the control bits in the option. The new flag is set to indicate that the
Root performs the proxy operation and that all nodes in the network Root performs the proxy operation and that all nodes in the network
must refrain from renewing the 6LBR state directly. The bit position must refrain from renewing the 6LBR state directly. The bit position
of the "P" flag is indicated in Section 12.1. of the "P" flag is indicated in Section 12.2.
Section 6.3.1. of [RFC6550] defines a 3-bit Mode of Operation (MOP) 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 in 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 value between 0 to 6. For a MOP value of 7 or above, the flag MAY
indicate something different and MUST NOT be interpreted as "Root indicate something different and MUST NOT be interpreted as "Root
Proxies EDAR/EDAC" unless the specification of the MOP indicates to Proxies EDAR/EDAC" unless the specification of the MOP indicates to
do so. 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 used in the DCO messages
[EFFICIENT-NPDAO] as well. Furthermore, this specification enables [EFFICIENT-NPDAO] as well. Furthermore, this specification enables
to use a RPL Status to transport the IPv6 ND Status defined for use to use a RPL Status to transport the IPv6 ND Status defined for use
in the EARO, more in Section 7. in the EARO, more in Section 7.
Section 6.7. of [RFC6550] introduces the RPL Control Message Options Section 6.7. of [RFC6550] introduces the RPL Control message Options
such as the RPL Target Option that can be included in a RPL Control 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 message such as the DAO. Section 8 updates the RPL Target Option to
optionally transport the ROVR used in the IPv6 Registration (see optionally transport the ROVR used in the IPv6 Registration (see
Section 3.2.3) so the RPL Root can generate a full EDAR Message. Section 3.2.3) so the RPL Root can generate a full EDAR message.
5. Updating RFC 8505 5. Updating RFC 8505
This document updates [RFC8505] to introduce a keep-alive EDAR This document updates [RFC8505] to introduce the anonymous EDAR and
message and a keep-alive NS(EARO) message. The keep-alive messages NS(EARO) messages. The anonymous messages are used for backward
are used for backward compatibility, when the DAO does not transport compatibility. The anonymous messages are recognizable by a zero
a ROVR as specified in Section 8. The keep-alive messages have a ROVR field and can only be used as a refresher for a pre-existing
zero ROVR field and can only be used to refresh a pre-existing state state associated to the Registered Address. More specifically, an
associated to the Registered Address. More specifically, a keep- anonymous message can only increase the lifetime and/or increment the
alive message can only increase the lifetime and/or increment the TID TID of an existing state at the 6LBR.
of the existing state in a 6LBR.
Upon the renewal of a 6LoWPAN ND Address Registration, this Upon the renewal of a 6LoWPAN ND Address Registration, this
specification changes the behavior of a RPL Router acting as 6LR for specification changes the behavior of a RPL Router acting as 6LR for
the Address Registration as follows. If the Root indicates the the registration. If the Root indicates the capability to proxy the
capability to proxy the EDAR/EDAC exchange to the 6LBR then the 6LR EDAR/EDAC exchange to the 6LBR then the 6LR refrains from sending an
refrains from sending an EDAR message; if the Root is separated from EDAR message; if the Root is separated from the 6LBR, the Root
the 6LBR, the Root regenerates the EDAR message to the 6LBR upon a regenerates the EDAR message to the 6LBR upon a DAO message that
DAO message that signals the liveliness of the Address. signals the liveliness of the Address. The regenerated message is
anonymous iff the DAO is a legacy message that does not carry a ROVR
as specified in Section 8.
6. Requirements on the RPL-Unware Leaf 6. 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 in order to obtain routing functionality is required from the RUL in order to obtain routing
services from the 6LR. services from the 6LR.
6.1. Support of 6LoWPAN ND 6.1. 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 option. The RUL MAY [RFC8505] and set the "R" flag in the EARO option. The RUL MUST NOT
request routing services from a 6LR if and only if the L, R and E request routing services from a 6LR unless the 6LR originates RA
flags are all set in the 6CIO [RFC7400] originated by the 6LR. messages with a CIO that has the L, P and E flags are all set as
discussed in Section 3.3.1.
The RUL MUST register to all the 6LRs from which it requests routing The RUL MUST register to all the 6LRs from which it requests routing
services. The Address Registrations SHOULD be performed in a rapid services. The Address Registrations SHOULD be performed in a rapid
sequence, using the exact same EARO for a same Address. Gaps between sequence, using the exact same EARO for a same Address. Gaps between
the Address Registrations will invalidate some of the routes till the the Address Registrations will invalidate some of the routes till the
Address Registration finally shows on those routes as well. Address Registration finally shows on those routes as well.
[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 refrain from using the Registered Address MUST support both cases and MUST refrain from using the address when
as specified by [RFC8505] depending on the Status value. the Status value indicates a rejection.
A RUL SHOULD support [AP-ND] to protect the ownership of its A RUL SHOULD support [AP-ND] to protect the ownership of its
addresses. addresses.
6.2. External Routes and RPL Artifacts 6.2. 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 that MUST be
followed when forwarding packets over an external route: followed for the routing operations to a RUL.
RPL data packets are often encapsulated using IP-in-IP and in Non- Non-Storing Mode DAO messages are used to signal external routes to
Storing Mode, packets going down will carry an SRH as well. RPL data the Root, even if the DODAG is operated in Storing Mode. A RUL is an
packets also typically carry a Hop-by-Hop Header to transport a RPL example of a destination that is reachable via an external route
Packet Information (RPI) [RFC6550]. These additional headers are which happens to be a Host route.
called RPL artifacts.
When IP-in-IP is used and the outer headers terminate at a 6LR down The Non-Storing Mode DAO messaging enables to advertise the 6LR that
the path (see Figure 10 for the compressed format in Storing Mode), serves the RUL and injects the route to the Root. It also forces all
then the 6LR decapsulates the IP-in-IP and the packet that is packets to the RUL to be routed via the Root since the path to the
forwarded to the external destination is free of RPL artifacts - but RUL is not known inside the RPL domain, even in Storing Mode.
possibly an RPI if packet was generated by a RAN in the same RPL
domain as the destination RUL.
Non-Storing Mode DAO messages are used to signal external routes to The use of Non-Storing Mode signaling in Storing Mode and the
the Root, even if the DODAG is operated in Storing Mode. This associated IP-in-IP encapsulation are transparent to intermediate
enables to advertise the 6LR that injects the route for use as tunnel Routers that only see packets back and forth between the Root and the
endpoint in the data path. 6LR and do not need a special support for external routes, so the
mmechanism is backward compatible.
For all external routes, the Root should use an IP-in-IP tunnel to The RPL data packets from/to a RUL are encapsulated using an IP-in-IP
that 6LR, with the RPL artifacts in the outer header to be stripped tunnel between the Root and the 6LR that serves the RUL, except for
by the 6LR. The IP-in-IP encapsulation may be avoided in Storing packets from the RUL to a RAN in the RPL domain. The RPL data
Mode if the path to the external destination beyond the 6LR is known packets also carry a Hop-by-Hop Header to transport a RPL Packet
to handle or ignore the RPL artifacts properly [RFC8200]. Information (RPI) [RFC6550]. In Non-Storing Mode, packets going down
carry a Source Routing Header (SRH). These headers are called the
"RPL artifacts" and can be compressed with [RFC8138].
A RUL is an example of a destination that is reachable via an RPL data packets going down to the RUL (see Figure 12 for the
external (Host) route for which IP-in-IP tunneling may be avoided as compressed format in Storing Mode) are decapsulated by the 6LR that
it ignores the RPI and the consumed SRH artifacts. The use of non- serves the RUL. The inner packet that is forwarded to the RUL is
Storing Mode signaling in Storing Mode and the associated IP-in-IP free of RPL artifacts, except for an RPI if the packet was generated
encapsulation are transparent to intermediate Routers that only see by a RAN in the same RPL domain as the RUL and reencapsulated with
packets back and forth between the Root and the 6LR and do not need a the original RPI still present in the inner header by the Root.
special support for external routes.
The RUL may not support IP-in-IP tunneling [RFC8504], so if IP-in-IP [USEofRPLinfo] expects the RUL to support the basic "IPv6 Node
is used, and unless the Root as a better knowledge, the tunnel should Requirements" [RFC8504], in particular to ignore the RPL artifacts
terminate at the 6LR that injected the external route to the RUL. that are either consumed or not applicable to a Host, which is the
case of the RPI.
Additionally, the RUL is not expected to support the compression Additionally, the RUL is not expected to support the compression
method defined in [RFC8138]. The 6LR that injected the route MUST method defined in [RFC8138]. The 6LR that injected the route MUST
uncompress the packet before forwarding over an external route, even uncompress the packet before forwarding over an external route, even
when delivering to a RUL, even when it is not the destination in the when delivering to a RUL, even when it is not the destination in the
outer header of the incoming packet, unless configured to do outer header of the incoming packet, unless configured to do
otherwise. otherwise.
6.2.1. Support of the HbH Header 6.2.1. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] sets the rules for forwarding IP-in-IP
either to the final 6LN or to a parent 6LR. In order to enable IP-
in-IP to the 6LN in Non-Storing Mode, the 6LN must be able to
decapsulate the tunneled packet and either drop the inner packet 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-
in-IP properly, the Root that encapsulates a packet to a RUL
terminates the IP-in-IP tunnel at the parent 6LR . For that reason,
it is beneficial but not necessary for a RUL to support IP-in-IP.
6.2.2. 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 unknown Option Type in a Hop-by-Hop
Header as prescribed by section 4.2 of [RFC8200]. This means in Header as prescribed by section 4.2 of [RFC8200]. This means in
particular that an RPI with an Option Type of 0x23 [USEofRPLinfo] is particular that an RPI with an Option Type of 0x23 [USEofRPLinfo] is
ignored when not understood. ignored when not understood.
6.2.2. Support of the Routing Header 6.2.3. 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 means in particular
that Routing Header with a Routing Type of 3 [RFC6553] is ignored that Routing Header with a Routing Type of 3 [RFC6553] is ignored
when the Segments Left is zero, and dropped otherwise. when the Segments Left is zero, and dropped otherwise.
6.2.3. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] sets the rules for forwarding IP-in-IP
either to the final 6LN or to a parent 6LR. In order to enable IP-
in-IP to the 6LN in Non-Storing Mode, the 6LN must be able to
decapsulate the tunneled packet and either drop the inner packet 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-
in-IP properly, the Root that encapsulates a packet to a RUL
terminates the IP-in-IP tunnel at the parent 6LR . For that reason,
it is beneficial but not necessary for a RUL to support IP-in-IP.
7. Updated RPL Status 7. 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 This specification extends the scope of the RPL Status to be used in
RPL DCO messages. Furthermore, this specification enables to carry RPL DCO messages. Furthermore, this specification enables to carry
the IPv6 ND Status values defined for use in the EARO and initially the IPv6 ND Status values defined for use in the EARO and initially
listed in table 1 of [RFC8505] in a RPL Status. Only EARO Status listed in table 1 of [RFC8505] in a RPL Status.
values in the range 0-63 can be transported.
The resulting RPL Status is as follows: Section 12.1 reduces the range of EARO Status values to 0-63 ensure
that they fit within a RPL Status as shown in Figure 3.
0 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: RPL Status subfields:
skipping to change at page 14, line 30 skipping to change at page 14, line 31
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 in a RPL
extension. extension.
When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a DAC When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a DAC
message, the RPL Root MUST copy the ARO Status unchanged in a RPL message, the RPL Root MUST copy the ARO Status unchanged in a RPL
Status with the 'A' bit set. Conversely the 6LR MUST copy the value Status with the 'A' bit set. The RPL Root MUST set the 'E' flag for
of the RPL Status unchanged in the EARO of an NA message that is all values in range 1-10 which are all considered rejections.
built upon a RPL Status with the 'A' bit set in a DCO or a DAO-ACK
message. Conversely, the 6LR MUST copy the value of the RPL Status unchanged
in the EARO of an NA message that is built upon a RPL Status with the
'A' bit set in a DCO or a DAO-ACK message.
8. Updated RPL Target option 8. 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 as illustrated in Figure 4. This enables the RPL Root to ROVR. This enables the RPL Root to generate a full EDAR message as
generate a full EDAR Message as opposed to a keep-alive EDAR that has opposed to an anonymous EDAR that has restricted properties.
restricted properties.
The Target Prefix MUST be aligned to the next 4-byte boundary after The Target Prefix field MUST be aligned to the next 4-byte boundary
the size indicated by the Prefix Length. if necessary it is padded after the size indicated by the Prefix Length. If necessary the
with zeros. The size of the ROVR is indicated in a new ROVR Type transported prefix MUST be padded with zeros.
field that is encoded to map the CodePfx in the EDAR message (see
section 4.2 of [RFC8505]).
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 format is backward compatible with the Target Option in Option. The size of the ROVR is indicated in a new ROVR Size field
[RFC6550] and SHOULD be used as a replacement. that is encoded to map one-to-one with the Code Suffix in the EDAR
message (see table 4 of [RFC8505]).
The modified format is illustrated in Figure 4. It is backward
compatible with the Target Option in [RFC6550] and SHOULD be used as
a replacement.
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 | Flags | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| Target Prefix (Variable Length) | | Target Prefix (Variable Length) |
. Aligned to 4-byte boundary . . Aligned to 4-byte boundary .
skipping to change at page 15, line 38 skipping to change at page 15, line 42
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 9. 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 9.1. General Flow
This specification enables to save the exchange of Extended Duplicate This specification enables to save the exchange of keep-alive
Address messages, EDAR and EDAC, from a 6LN all the way to the 6LBR Extended Duplicate Address messages, EDAR and EDAC, from a 6LN all
across a RPL mesh, for the sole purpose of refreshing an existing the way to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC
state in the 6LBR. Instead, the EDAR/EDAC exchange is proxied by the exchange with the 6LBR is proxied by the RPL Root upon a DAO message
RPL Root upon a DAO message that refreshes the RPL routing state. that refreshes the RPL routing state.
To achieve this, the lifetimes and sequence counters in 6LoWPAN ND To achieve this, the lifetimes and sequence counters in 6LoWPAN ND
and RPL are aligned. In other words, the Path Sequence and the Path 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 Lifetime in the DAO message are taken from the Transaction ID and the
Address Registration lifetime in the NS(EARO) message from the 6LN. Address Registration lifetime in the NS(EARO) message from the 6LN.
In that flow, the RPL Root acts as a proxy to refresh the state in The proxy operation applies to both RULs and RANs. In a RPL network
the 6LBR. The proxy operation applies to both RUL and RAN. This where the function is enabled, refreshing the state in the 6LBR is
means that in a RPL network where the function is enabled, refreshing the responsibility of the Root. Consequently, only addresses that
the state in the 6LBR is the responsibility of the Root. are injected in RPL will be kept alive by the RPL Root.
Consequently, only addresses that are injected in RPL will be kept
alive by the RPL Root.
In a same fashion, if an additional routing protocol is deployed on a In a same fashion, if an additional routing protocol is deployed on a
same network, that additional routing protocol may need to handle the same network, that additional routing protocol may need to handle the
keep alive procedure for the addresses that it serves. keep alive procedure for the addresses that it serves.
On the first Address Registration, illustrated in Figure 5 and On the first Address Registration, illustrated in Figure 5 and
Figure 7 for RPL Non-Storing and Storing Mode respectively, the Figure 8 for RPL Non-Storing and Storing Mode respectively, the
Extended Duplicate Address exchange takes place as prescribed by Extended Duplicate Address exchange takes place as prescribed by
[RFC8505]. Any of the functions 6LR, Root and 6LBR might be [RFC8505]. Any of the functions 6LR, Root and 6LBR might be
collapsed in a single node. collapsed in a single node.
When successful, the flow creates a Neighbor Cache Entry (NCE) in the When successful, the flow creates a Neighbor Cache Entry (NCE) in the
6LR, and the 6LR injects the Registered Address in RPL using DAO/DAO- 6LR, and the 6LR injects the Registered Address in RPL using DAO/DAO-
ACK exchanges all the way to the RPL DODAG Root. The protocol does ACK exchanges all the way to the RPL DODAG Root. The protocol does
not carry a specific information that the Extended Duplicate Address not carry a specific information that the Extended Duplicate Address
messages were already exchanged, so the Root proxies them anyway. messages were already exchanged, so the Root proxies them anyway.
9.1.1. In RPL Non-Storing-Mode 9.1.1. In RPL Non-Storing-Mode
In Non-Storing Mode, the DAO message flow can be nested within the In Non-Storing Mode, the DAO message flow can be nested within the
Address Registration flow as illustrated in Figure 5 and it is Address Registration flow as illustrated in Figure 5.
possible to carry information such as an updated lifetime from the
6LBR all the way back to the 6LN.
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | Extended DAR | | | Extended DAR |
| |--------------------------------->| | |--------------------------------->|
| | | | | |
| | Extended DAC | | | Extended DAC |
| |<---------------------------------| | |<---------------------------------|
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | (keep-alive) EDAR | | | | (anonymous) EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
(in case if an Error not reported in DAO-ACK)
| | | |
| | DCO | |
| |<-------------| |
| NA(EARO) | | |
|<---------------| | |
| | | |
Figure 5: First Registration Flow in Non-Storing Mode Figure 5: First Registration Flow in Non-Storing Mode
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
value of the status that indicates the issue can be passed from
6LoWPAN ND to RPL and back as illustrated in Figure 6.
6LN 6LR Root 6LBR
| | | |
| | | NA(EARO, Status) |
| | |<-----------------|
| | DCO(Status) | |
| |<------------| |
| NA(EARO, Status) | | |
|<-----------------| | |
| | | |
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 an Address re-
Registration, as illustrated in Figure 6, the 6LR redistributes the Registration, as illustrated in Figure 7, the 6LR redistributes the
Registered Address NS(EARO) in RPL. Registered Address NS(EARO) in RPL.
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | (keep-alive) EDAR | | | | (anonymous) EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 6: Next Registration Flow in Non-Storing Mode Figure 7: Next Registration Flow in Non-Storing Mode
This causes the RPL DODAG Root to refresh the state in the 6LBR with This causes the RPL DODAG Root to refresh the state in the 6LBR with
an EDAC message or a keep-alive EDAC if the ROVR is not indicated in an EDAC message or an anonymous EDAC if the ROVR is not indicated in
the Target Option. In any case, the EDAC message sent in response by the Target Option. In both cases, the EDAC message sent in response
the 6LBR contains the actual value of the ROVR field for that Address by the 6LBR contains the actual value of the ROVR field for that
Registration. In case of an error on the proxied EDAR flow, the Address Registration. In case of an error on the proxied EDAR flow,
error SHOULD be returned in the DAO-ACK - if one was requested - 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 using a RPL Status with the 'A' flag set that imbeds a 6LoWPAN Status
value as discussed in Section 7. value as discussed in Section 7.
If the Root could not return the negative Status in the DAO-ACK then If the Root could not return the negative Status in the DAO-ACK then
it sends an asynchronous Destination Cleanup Object (DCO) message it sends an asynchronous Destination Cleanup Object (DCO) message
[EFFICIENT-NPDAO] to the 6LR placing the negative Status in the RPL [EFFICIENT-NPDAO] to the 6LR placing the negative Status in the RPL
Status with the 'A' flag set. Note that if both are used in a short 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 interval of time, the DAO-ACK and DCO messages are not guaranteed to
arrive in the same order at the 6LR. arrive in the same order at the 6LR.
skipping to change at page 19, line 11 skipping to change at page 18, line 28
else, if the 'E' flag is set, indicating a rejection, then the status 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 4 "Removed" is used; else, the ND Status of 0 indicating "Success" is
used. used.
9.1.2. In RPL Storing-Mode 9.1.2. In RPL Storing-Mode
In RPL Storing Mode, the DAO-ACK is optional. When it is used, it is In RPL Storing Mode, the DAO-ACK is optional. When it is used, it is
generated by the RPL parent, which does not need to wait for the generated by the RPL parent, which does not need to wait for the
grand-parent to send the acknowledgement. A successful DAO-ACK is grand-parent to send the acknowledgement. A successful DAO-ACK is
not a guarantee that the DAO has yet reached the Root or that the not a guarantee that the DAO has yet reached the Root or that the
keep-alive EDAR has succeeded. EDAR has succeeded.
6LN 6LR 6LR Root 6LBR 6LN 6LR 6LR Root 6LBR
| | | | | | | | | |
| NS(EARO) | | | | | NS(EARO) | | | |
|-------------->| | | | |-------------->| | | |
| NA(EARO) | | | | | NA(EARO) | | | |
|<--------------| | | | |<--------------| | | |
| | | | | | | | | |
| | DAO | | | | | DAO | | |
| |-------------->| | | | |-------------->| | |
| | DAO-ACK | | | | | DAO-ACK | | |
| |<--------------| | | | |<--------------| | |
| | | | | | | | | |
| | | DAO | | | | | DAO | |
| | |-------------->| | | | |-------------->| |
| | | DAO-ACK | | | | | DAO-ACK | |
| | |<--------------| | | | |<--------------| |
| | | | | | | | | |
| | | | keep-alive EDAR | | | | | (anonymous) EDAR |
| | | |---------------->| | | | |----------------->|
| | | | EDAC(ROVR) | | | | | EDAC(ROVR) |
| | | |<----------------| | | | |<-----------------|
| | | | | | | | | |
(in case if an Error) Figure 8: Next Registration Flow in Storing Mode
| | | | |
| | DCO | |
| |<------------------------------| |
| NA(EARO) | | | |
|<--------------| | | |
| | | | |
Figure 7: Next Registration Flow in Storing Mode If the keep-alive fails, or an asynchronous issue is reported, the
path can be cleaned up asynchronously using a DCO message
[EFFICIENT-NPDAO] as illustrated in Figure 9 and described in further
details in Section 9.2.3.
If the keep alive fails, the path is cleaned up asynchronously using 6LN 6LR 6LR Root 6LBR
a DCO message [EFFICIENT-NPDAO] as illustrated in Figure 7 and | | | | |
described in further details in Section 9.2.3. | | | | NA(EARO, Status) |
| | | |<-----------------|
| | | | |
| | | DCO(Status) | |
| | |<------------| |
| | | | |
| | DCO(Status) | | |
| |<------------| | |
| | | | |
| NA(EARO, Status) | | | |
|<-----------------| | | |
| | | | |
Figure 9: Issue in Storing Mode
9.2. Detailed Operation 9.2. Detailed Operation
9.2.1. By the 6LN 9.2.1. By the 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:
* The 6LN obtains an IPv6 global address, for instance using * The 6LN obtains an IPv6 global address, either using Stateless
autoconfiguration [RFC4862] based on a Prefix Information Option Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix
(PIO) [RFC4861] found in a Router Advertisement message or by some Information Option (PIO) [RFC4861] found in a Router Advertisement
other means such as DHCPv6 [RFC3315]. message, or some other means such as DHCPv6 [RFC3315].
* Once it has formed an address, the 6LN (re)registers its address * 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]. Registration, as prescribed by [RFC6775] and [RFC8505].
* A 6LN acting as a RUL sets the "R" flag in the EARO whereas a 6LN
acting as a RAN does not set the "R" flag as prescribed by
[RFC8505] section 5.1.
* Upon each consecutive Address Registration, the 6LN increases the
TID field in the EARO, as prescribed by [RFC8505] section 5.2.
* The 6LN can register to more than one 6LR at the same time. In * The 6LN can register to more than one 6LR at the same time. In
that case, it MUST use the same value of TID for all of the that case, it MUST use the same value of TID for all of the
parallel Address Registrations. parallel Address Registrations.
* 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 acting
as a RAN it never does. If the "R" flag is set in the NS but not
echoed in the NA, the RUL SHOULD attempt to use another 6LR.
* Upon each consecutive Address Registration, the 6LN increases the
TID field in the EARO, as prescribed by [RFC8505] section 5.2.
* The 6LN may use any of the 6LRs to which it register to forward * The 6LN may use any of the 6LRs to which it register to forward
its packets. Using a 6LR to which the 6LN is not registered may its packets. 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). 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 of but it MAY do so. For instance, if the RUL has a minimal awareness
the RPL Instance and can build an RPI. A RUL that places an RPI in a of the RPL Instance then it can build an RPI. A RUL that places an
data packet MUST indicate the RPLInstanceID that corresponds to the RPI in a data packet MUST indicate the RPLInstanceID that corresponds
RPL Instance the packet should be injected into. All the flags and to the RPL Instance the packet should be injected into. All the
the Rank field are set to zero as specified by section 11.2 of flags and the Rank field are set to zero as specified by section 11.2
[RFC6550]. of [RFC6550].
9.2.2. By the 6LR 9.2.2. By the 6LR
Also as prescribed by [RFC8505], the 6LR generates a DAR message upon Also as prescribed by [RFC8505], the 6LR generates an EDAR message
reception of a valid NS(EARO) message for the Address Registration of upon reception of a valid NS(EARO) message for the Address
a new IPv6 Address by a 6LN. If the Duplicate Address exchange Registration of a new IPv6 Address by a 6LN. If the Duplicate
succeeds, then the 6LR installs an NCE. If the "R" flag was set in Address exchange succeeds, then the 6LR installs an NCE. If the "R"
the EARO of the NS message, and this 6LR can manage the reachability flag was set in the EARO of the NS message, and this 6LR can manage
of Registered Address, then the 6LR sets the "R" flag in the EARO of the reachability of Registered Address, then the 6LR sets the "R"
the NA message that is sent in response. flag in the EARO of the NA message that is sends in response.
From then on, the 6LN periodically sends a new NS(EARO) to refresh From then on, the 6LN periodically sends a new NS(EARO) to refresh
the NCE state before the lifetime indicated in the EARO expires, with the NCE state before the lifetime indicated in the EARO expires, with
TID that is incremented each time till it wraps in a lollipop fashion TID that is incremented each time till it wraps in a lollipop fashion
(see section 5.2.1 of [RFC8505] which is fully compatible with (see section 5.2.1 of [RFC8505] which is fully compatible with
section 7.2 of [RFC6550]). As long as the R flag is set and this section 7.2 of [RFC6550]). As long as the "R" flag is set and this
Router can still manage the reachability of Registered Address, the Router can still manage the reachability of Registered Address, the
6LR keeps setting the "R" flag in the EARO of the response NA 6LR keeps setting the "R" flag in the EARO of the response NA
message, but the exchange of Extended Duplicate Address messages is message, but the exchange of keep-alive Extended Duplicate Address
skipped. messages with the 6LBR is avoided if the RPL Root has indicated that
it proxies for it.
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 enacapsulate the packet to the packet, in which case the 6LR MUST encapsulate the packet to the Root
Root adding an RPI in the outer header. if the "I" field is not adding an RPI in the outer header. If the Opaque field is zero, the
zero, then the 6LR MUST consider that the Opaque field is zero. If 6LR is free to use the default RPL Instance (zero) for the registered
the Opaque field is not set to zero, then it should carry a address or to select an Instance of its choice.
RPLInstanceID for the Instance suggested by the 6LN. If the 6LR does
not participate to the associated Instance, then the 6LR MUST if the "I" field is not zero, then the 6LR MUST consider that the
consider that the Opaque field is zero. If the Opaque field is zero, Opaque field is zero. If the Opaque field is not zero, then it is
the 6LR is free to use the default RPL Instance (zero) for the expected to carry a RPLInstanceID for the RPL Instance suggested by
registered address or to select an Instance of its choice; else, that 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
is if the 6LR participates to the suggested Instance, then the 6LR is if the 6LR participates to the suggested Instance, then the 6LR
SHOULD use that Instance for the registered address. 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:
* The Registered Address is placed in a RPL Target Option in the DAO * The Registered Address is placed in a RPL Target Option in the DAO
message as the Target Prefix, and the Prefix Length is set to 128; message as the Target Prefix, and the Prefix Length is set to 128;
* RPL Non-Storing Mode is used, and the 6LR indicates one of its * RPL Non-Storing Mode is used, and the 6LR indicates one of its
global IPv6 unicast addresses as the Parent Address in the RPL global or unique-local IPv6 unicast addresses as the Parent
Transit Information Option (TIO) associated to the Target Option. Address in the associated RPL Transit Information Option (TIO).
* the External 'E' flag in the TIO is set to indicate that the 6LR * the External 'E' flag in the TIO is set to indicate that the 6LR
redistributes an external target into the RPL network. redistributes an external target into the RPL network.
* the Path Lifetime in the TIO is computed from the Lifetime in the * the Path Lifetime in the TIO is computed from the Lifetime in the
EARO Option to adapt it to the Lifetime Units used in the RPL EARO Option to adapt it to the Lifetime Units used in the RPL
operation. Note that if the lifetime is 0, then the 6LR generates operation. Note that if the lifetime is 0, then the 6LR generates
a No-Path DAO message that cleans up the routes down to the a No-Path DAO message that cleans up the routes down to the
Address of the 6LN; Address of the 6LN;
* the Path Sequence in the TIO is set to the TID value found in the * the Path Sequence in the TIO is set to the TID value found in the
EARO option; EARO option;
Upon a successful NS/NA(EARO) exchange: if the "R" flag was set in Upon an NS(EARO), iff the "R" flag was set, the 6LR SHOULD inject the
the EARO of the NS message, then the 6LR SHOULD inject the Registered Registered Address in RPL by sending a DAO message on behalf of the
Address in RPL by sending a DAO message on behalf of the 6LN; else 6LN. If the Registration Lifetime was 0, the effect is to remove the
the 6LR MUST NOT inject the Registered Address into RPL. route and then the NCE.
If a DAO-ACK is not requested, or has a Status that is not a If for whatever reason the 6LR does not inject the Registered Address
rejection, indicating the DAO was accepted respectively by a parent in RPL, it MUST send an NA(EARO) back with the appropriate status and
in Storing Mode or by the Root in non-Storing Mode, the 6LR replies the "R" flag not set.
with a NA(EARO) to the RUL with a Status of 0 (Success).
In case of a DAO-ACK or a DCO indicating a rejection and transporting If the 6LR injects the Registered Address in RPL and either a DAO-ACK
an EARO Status Value of 5 (Validation Requested) the 6LR challenges was not requested or is received with a RPL Status that is not a
the 6LN for ownership of the address, as described in section 6.1 of rejection ("E" flag not set), the 6LR MUST install or refresh the NCE
[RFC8505]. If the challenge succeeds then the operations continue as for the address and reply to the RUL with an NA(EARO) with a Status
normal. In particular a DAO message is generated upon the NS(EARO) of 0 (Success) and the "R" flag set.
that proves the ownership of the address. If the challenge failed
the 6LR MUST refrain from injecting the address in RPL and may take In case of a DAO-ACK or a DCO indicating transporting an EARO Status
actions to protect itself against DoS attacks by a rogue 6LN, see Value of 5 (Validation Requested), a 6LR that supports Address
Section 11 Protected Neighbor Discovery (AP-ND) MUST challenge the 6LN for
ownership of the address, as described in section 6.1 of [AP-ND]. If
the challenge succeeds then the operations continue as normal. In
particular a DAO message is generated upon the NS(EARO) that proves
the ownership of the address. If the challenge failed, the 6LR
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.
If the 6LR does not support AP-ND, it MUST send an NA to the 6LN with
a Status of 0 (Success) and the "R" flag not set.
The other rejection codes indicate that the 6LR failed to inject the The other rejection codes indicate that the 6LR failed to inject the
address into the RPL network. If an EARO Status is transported, the address into the RPL network. If an EARO Status is transported, the
6LR MUST send a NA(EARO) to the RUL with that Status value. If for 6LR MUST send a NA(EARO) to the RUL with that Status value, and the
any other reason the 6LR fails to inject the address into the RPL "R" flag not set. Similarly, upon receiving a DCO message indicating
network, the 6LR SHOULD send a NA(EARO) to the RUL with a Status of 2 that the address of a RUL should be removed from the routing table,
(Out of Storage) which indicates a possibility to retry later. the 6LR issues an asynchronous NA(EARO) to the RUL with the embedded
Similarly, upon a DCO message indicating that the address of a RUL ND Status value if there was one, and the "R" flag not set.
should be removed from the routing table, the 6LR issues an
asynchronous NA(EARO) to the RUL with the embedded ND Status value.
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 the 6LR was redistributing the Registered Address due to previous and a Registration Lifetime that is not 0, and the 6LR was
NS(EARO) messages with the flag set, then it MUST stop injecting the redistributing the Registered Address due to previous NS(EARO)
address. It is up to the Registering Node to maintain the messages with the flag set, then it MUST stop injecting the address.
corresponding route from then on, either keeping it active by sending It is up to the Registering 6LN to maintain the corresponding route
further DAO messages, or destroying it using a No-Path DAO. from then on, either keeping it active via a different 6LR or by
acting as a RAN and managing its own reachability.
9.2.3. By the RPL Root 9.2.3. By the RPL Root
In RPL Storing Mode of Operation (MOP), the DAO message is propagated In RPL Storing Mode of Operation (MOP), the DAO message is propagated
from child to parent all the way to the Root along the DODAG, from child to parent all the way to the Root along the DODAG,
populating routing state as it goes. In Non-Storing Mode, The DAO populating routing state as it goes. In Non-Storing Mode, The DAO
message is sent directly to the RPL Root. Upon reception of a DAO message is sent directly to the RPL Root. Upon reception of a DAO
message, for each RPL Target option that creates or updates an message, for each RPL Target option that creates or updates an
existing RPL state: existing RPL state:
* the Root notifies the 6LBR using an internal API if they are co- * the Root notifies the 6LBR using an internal API if they are co-
located, or performs an EDAR/EDAC exchange on behalf of the 6LR if located, or using a proxied EDAR/EDAC exchange if they are
they are separated. If the Target option transports a ROVR, then separated. If the RPL Target option transports a ROVR, then the
the Root MUST use it to build a full EDAR message as the 6LR Root MUST use it to build a full EDAR message; else, an anonymous
would. Else, a keep-alive EDAR is used with the ROVR field set to EDAR is used with the ROVR field set to zero.
zero.
An EDAR message MUST be constructed as follows: The EDAR message MUST be constructed as follows:
* The Target IPv6 address from in the RPL Target Option is placed in * The Target IPv6 address from the RPL Target Option is placed in
the Registered Address field of the EDAR message and in the Target the Registered Address field of the EDAR message;
field of the NS message, respectively;
* the Registration Lifetime is adapted from the Path Lifetime in the * the Registration Lifetime is adapted from the Path Lifetime in the
TIO by converting the Lifetime Units used in RPL into units of 60 TIO by converting the Lifetime Units used in RPL into units of 60
seconds used in the 6LoWPAN ND messages; seconds used in the 6LoWPAN ND messages;
* the RPL Root indicates its own MAC Address as Source Link Layer
Address (SLLA) in the NS(EARO);
* the TID value is set to the Path Sequence in the TIO and indicated * the TID value is set to the Path Sequence in the TIO and indicated
with an ICMP code of 1 in the EDAR message; with an ICMP code of 1 in the EDAR message;
* when present in the RPL Target option, the ROVR field is used as * If the ROVR is present in the RPL Target option, it is copied as
is in the EDAR and the ICMP Code Suffix is set to the appropriate is in the EDAR and the ICMP Code Suffix is set to the appropriate
value as shown in Table 4 of [RFC8505] depending on the length of value as shown in Table 4 of [RFC8505] depending on the size of
the ROVR field. If it is not present the ROVR field in the EDAR the ROVR field; else, the ROVR field in the EDAR is set to zero
is set to zero indicating that this is a keep-alive EDAR. indicating an anonymous EDAR.
Upon a Status value in an EDAC message that is not "Success", the Upon a Status value in an EDAC message that is not "Success", the
Root SHOULD destroy the formed paths using either a DAO-ACK (in Non- Root SHOULD destroy the formed paths using either a DAO-ACK (in Non-
Storing Mode) or a DCO downwards as specified in [EFFICIENT-NPDAO]. Storing Mode) or a DCO downwards as specified in [EFFICIENT-NPDAO].
Failure to destroy the former path would result in Stale routing Failure to destroy the former path would result in Stale routing
state and local black holes if the address belongs to another party state and local black holes if the address belongs to another party
elsewhere in the network. The RPL Status value that maps the 6LowpAN elsewhere in the network. The RPL Status value that maps the 6LoWPAN
ND Status value MUST be placed in the DCO. ND Status value MUST be embedded in the RPL Status in the DCO.
9.2.4. By the 6LBR 9.2.4. By the 6LBR
Upon reception of an EDAR message with the ROVR field is set to zero Upon reception of an EDAR message with the ROVR field is set to zero
indicating a keep-alive EDAR, the 6LBR checks whether an entry exists indicating an anonymous EDAR, the 6LBR checks whether an entry exists
for the and computes whether the TID in the DAR message is fresher for the and computes whether the TID in the DAR message is fresher
than that in the entry as prescribed in section 4.2.1. of [RFC8505]. than that in the entry as prescribed in section 4.2.1. of [RFC8505].
If the entry does not exist, the 6LBR does not create the entry, and If the entry does not exist, the 6LBR does not create the entry, and
answers with a Status "Removed" in the EDAC message. answers with a Status "Removed" in the EDAC message. If the entry
exists but is not fresher, the 6LBR does not update the entry, and
If the entry exists but is not fresher, the 6LBR does not update the answers with a Status "Success" in the EDAC message.
entry, and answers with a Status "Success" in the EDAC message.
If the entry exists and the TID in the DAR message is fresher, the If the entry exists and the TID in the DAR message is fresher, the
6LBR updates the TID in the entry, and if the lifetime of the entry 6LBR updates the TID in the entry, and if the lifetime of the entry
is extended by the Registration Lifetime in the DAR message, it also is extended by the Registration Lifetime in the DAR message, it also
updates the lifetime of the entry. In that case, the 6LBR replies updates the lifetime of the entry. In that case, the 6LBR replies
with a Status "Success" in the DAC message. with a Status "Success" in the DAC message.
The EDAC that is constructed is the same as if the keep-alive EDAR The EDAC that is constructed is the same as if the anonymous EDAR was
was a full EDAR, and includes the ROVR that is associated to the a full EDAR, and includes the ROVR that is associated to the Address
Address Registration. Registration.
10. Protocol Operations for Multicast Addresses 10. 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 if the interested children. This remains true when unicast to each if 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 8, the On the first Address Registration, as illustrated in Figure 10, 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. Since multicast order to start receiving the flow immediately. Since multicast
Layer-2 messages are avoided, it is important that the asynchronous Layer-2 messages are avoided, it is important that the asynchronous
messages for unsolicited Report and Done are sent reliably, for messages for unsolicited Report and Done are sent reliably, for
instance using an Layer-2 acknoledgement, or attempted multiple instance using an Layer-2 acknoledgement, or attempted multiple
times. times.
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
of the Query Interval, yet larger to account for variable propagation
delays.
The Root proxies the MLD echange as listener with the 6LBR acting 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 if
it is already registered as a listener for that address, and if not,
it performs its own unsolicited Report for the multicast target.
6LN 6LR Root 6LBR 6LN 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 8: First Multicast Registration Flow Figure 10: First Multicast Registration Flow
An Address re-Registration is pulled by 6LR acting as querier. Note The 6LR acts as a generic MLD querier and generates a DAO for the
that the message may be sent unicast to all the known individual multicast target. The lifetime of the DAO is set to be in the order
listeners. Upon a time out of the Query Interval, the 6LR sends a of the Query Interval, yet larger to account for variable propagation
Query to each of its listeners, and gets a Report back that is mapped delays.
into a DAO, as illustrated in Figure 9:
The Root proxies the MLD echange as listener with the 6LBR acting 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 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
querier. Note that th message may be sent unicast to all the known
individual listeners. Upon a time 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 11:
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | | | | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 9: Next Registration Flow Figure 11: 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 11. Security Considerations
The LLN nodes depend on the 6LBR and the RPL participants for their The LLN nodes depend on the 6LBR and the RPL participants for their
operation. A trust model must be put in place to ensure that the operation. A trust model must be put in place to ensure that the
right devices are acting in these roles, so as to avoid threats such right devices are acting in these roles, so as to avoid threats such
as black-holing, (see [RFC7416] section 7) or bombing attack whereby as black-holing, (see [RFC7416] section 7) or bombing attack whereby
an impersonated 6LBR would destroy state in the network by using the an impersonated 6LBR would destroy state in the network by using the
"Removed" Status code. This trust model could be at a minimum based "Removed" Status code.
on a Layer-2 access control, or could provide role validation as
well. This is a generic 6LoWPAN requirement, see Req5.1 in
Appendix of [RFC8505].
The keep-alive EDAR message does not carry a valid Registration This trust model could be at a minimum based on a Layer-2 Secure
Unique ID [RFC8505] and it cannot be used to create a binding state joining and the Link-Layer security. This is a generic 6LoWPAN
in the 6LBR. The 6LBR MUST NOT create an entry based on a keep-alive requirement, see Req5.1 in Appendix of [RFC8505].
EDAR that does not match an existing entry. All it can do is refresh
the lifetime and the TID of an existing entry. 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
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 that does not match an
existing entry. 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 use to maitain 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 the it is possible to validate the origin of an address that whereby the it is possible to validate the origin of an address that
is injected in a DAO. This specification makes a first step in that is 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 by the 6LR that
serves it. serves it.
12. IANA Considerations 12. IANA Considerations
12.1. New DODAG Configuration Option Flag 12.1. Resizing the ARO Status values
IANA is requested to modify the Address Registration Option Status
Values Registry as follows: The unassigned values range is reduced
from 11-255 to 11-63.
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
12.2. RPL Target Option Flags 12.3. RPL Target Option Flags
Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL
Target Option Flags field. This specification reduces the field to 4 Target Option Flags field. This specification reduces the field to 4
bits. The IANA is requested to reduce the size of the registry bits. The IANA is requested to reduce the size of the registry
accordingly. accordingly.
12.3. New Subregistry for the RPL Non-Rejection Status values 12.4. 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 RCO Messages, Rejection Status values for use in RPL DAO-ACK and RCO messages,
under the ICMPv6 parameters registry. 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 3:
+-------+------------------------+-----------+ +-------+------------------------+-----------+
| 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 3: Acceptance values of the RPL Status
12.4. New Subregistry for the RPL Rejection Status values 12.5. 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, under the Status values for use in RPL DAO-ACK and RCO messages, under the
ICMPv6 parameters registry. 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 4:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
skipping to change at page 30, line 14 skipping to change at page 29, line 46
[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
Perkins, "Registration Extensions for IPv6 over Low-Power Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, [AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
"Address Protected Neighbor Discovery for Low-power and "Address Protected Neighbor Discovery for Low-power and
Lossy Networks", Work in Progress, Internet-Draft, draft- Lossy Networks", Work in Progress, Internet-Draft, draft-
ietf-6lo-ap-nd-13, 6 January 2020, ietf-6lo-ap-nd-19, 6 February 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-13>. <https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-19>.
[USEofRPLinfo] [USEofRPLinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPI Robles, I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes and IPv6-in- option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", Work in IPv6 encapsulation in the RPL Data Plane", Work in
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-34, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-36,
20 January 2020, <https://tools.ietf.org/html/draft-ietf- 26 February 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-34>. roll-useofrplinfo-36>.
[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-17, 30 October 2019, draft-ietf-roll-efficient-npdao-17, 30 October 2019,
<https://tools.ietf.org/html/draft-ietf-roll-efficient- <https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-17>. npdao-17>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
skipping to change at page 31, line 31 skipping to change at page 31, line 16
[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch", Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016, RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>. <https://www.rfc-editor.org/info/rfc8025>.
[RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node [RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504, Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
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
Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-19, 3 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-backbone-
router-19>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 10 illustrates the case in Storing Mode where the packet is Figure 12 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].
The difference with the format presented in Figure 19 of [RFC8138] is
the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
destination address of the outer IPv6 header.
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|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
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
No RPL artifact <- No RPL artifact ...
Figure 10: Encapsulation to Parent 6LR in Storing Mode Figure 12: Encapsulation to Parent 6LR in Storing Mode
In Figure 10, the source of the IP-in-IP encapsulation is the Root, The difference with the example format presented in Figure 19 of
[RFC8138] 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 IPv6 header. In the original example the
destination IP of the outer header was elided and was implicitly the
same address as the destination of the inner header. Type 1 was
arbitrarily chosen for this example, and the size of 0 denotes a
single address in the SRH.
In Figure 12, 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.
In Storing Mode, it is placed as the single entry in an SRH-6LoRH as In Storing Mode, it is placed as the single entry in an SRH-6LoRH as
the first 6LoRH. Since there is a single entry so the SRH-6LoRH Size the first 6LoRH. Since there is a single entry so the SRH-6LoRH Size
is 0. In this particular example, the 6LR address can be compressed is 0. In this particular example, the 6LR address can be compressed
to 2 bytes so a Type of 1 is used. It results that the total length to 2 bytes so a Type of 1 is used. It results that the total length
of the SRH-6LoRH is 4 bytes. 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 10 with possibly more hops in the SRH- to that represented in Figure 12 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.
Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP
6LoRH is removed, all the Router headers that precede it are also 6LoRH is removed, all the Router headers that precede it are also
removed. removed.
 End of changes. 119 change blocks. 
397 lines changed or deleted 454 lines changed or added

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