draft-ietf-roll-unaware-leaves-27.txt   draft-ietf-roll-unaware-leaves-28.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550, 6775, 8505 (if approved) M. Richardson Updates: 6550, 6775, 8505 (if approved) M. Richardson
Intended status: Standards Track Sandelman Intended status: Standards Track Sandelman
Expires: 20 June 2021 17 December 2020 Expires: 21 June 2021 18 December 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-27 draft-ietf-roll-unaware-leaves-28
Abstract Abstract
This specification updates RFC6550, RFC6775, and RFC8505. It This specification updates RFC6550, RFC6775, and RFC8505. It
provides a mechanism for a host that implements a routing-agnostic provides a mechanism for a host that implements a routing-agnostic
interface based on 6LoWPAN Neighbor Discovery to obtain reachability interface based on 6LoWPAN Neighbor Discovery to obtain reachability
services across a network that leverages RFC6550 for its routing services across a network that leverages RFC6550 for its routing
operations. operations.
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 20 June 2021. This Internet-Draft will expire on 21 June 2021.
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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 6 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 6
2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3. References . . . . . . . . . . . . . . . . . . . . . . . 7 2.3. References . . . . . . . . . . . . . . . . . . . . . . . 7
3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 8 3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 8
4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 9 4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 9
4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 9 4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 9
4.2. RFC 8505 Extended Address Registration . . . . . . . . . 9 4.2. RFC 8505 Extended Address Registration . . . . . . . . . 10
4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 10 4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 10
4.2.2. TID, "I" Field and Opaque Fields . . . . . . . . . . 10 4.2.2. TID, "I" Field and Opaque Fields . . . . . . . . . . 11
4.2.3. Route Ownership Verifier . . . . . . . . . . . . . . 11 4.2.3. Route Ownership Verifier . . . . . . . . . . . . . . 11
4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 11 4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 11
4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 12 4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 12
5. Requirements on the RPL-Unware leaf . . . . . . . . . . . . . 12 5. Requirements on the RPL-Unware leaf . . . . . . . . . . . . . 13
5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 12 5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 13
5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 13 5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 14
5.3. Support of the Hop-by-Hop Header . . . . . . . . . . . . 13 5.3. Support of the Hop-by-Hop Header . . . . . . . . . . . . 14
5.4. Support of the Routing Header . . . . . . . . . . . . . . 13 5.4. Support of the Routing Header . . . . . . . . . . . . . . 14
6. Enhancements to RFC 6550 . . . . . . . . . . . . . . . . . . 14 6. Enhancements to RFC 6550 . . . . . . . . . . . . . . . . . . 14
6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 14 6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 15
6.2. Additional Flag in the RPL DODAG Configuration Option . . 16 6.2. Additional Flag in the RPL DODAG Configuration Option . . 17
6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 17 6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 18
7. Enhancements to draft-ietf-roll-efficient-npdao . . . . . . . 19 7. Enhancements to draft-ietf-roll-efficient-npdao . . . . . . . 20
8. Enhancements to RFC 6775 and RFC8505 . . . . . . . . . . . . 19 8. Enhancements to RFC6775 and RFC8505 . . . . . . . . . . . . . 20
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 20 9. Protocol Operations for Unicast Addresses . . . . . . . . . . 20
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 20 9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 21
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 23 9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 24
9.2.1. Perspective of the 6LN Acting as RUL . . . . . . . . 23 9.2.1. Perspective of the 6LN Acting as RUL . . . . . . . . 24
9.2.2. Perspective of the 6LR Acting as Border router . . . 25 9.2.2. Perspective of the 6LR Acting as Border router . . . 25
9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 29 9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 30
9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 30 9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 31
10. Protocol Operations for Multicast Addresses . . . . . . . . . 30 10. Protocol Operations for Multicast Addresses . . . . . . . . . 31
11. Security Considerations . . . . . . . . . . . . . . . . . . . 33 11. Security Considerations . . . . . . . . . . . . . . . . . . . 34
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
12.1. Fixing the Address Registration Option Flags . . . . . . 34 12.1. Fixing the Address Registration Option Flags . . . . . . 35
12.2. Resizing the ARO Status values . . . . . . . . . . . . . 35 12.2. Resizing the ARO Status values . . . . . . . . . . . . . 36
12.3. New RPL DODAG Configuration Option Flag . . . . . . . . 35 12.3. New RPL DODAG Configuration Option Flag . . . . . . . . 36
12.4. RPL Target Option Registry . . . . . . . . . . . . . . . 35 12.4. RPL Target Option Registry . . . . . . . . . . . . . . . 36
12.5. New Subregistry for RPL Non-Rejection Status values . . 36 12.5. New Subregistry for RPL Non-Rejection Status values . . 37
12.6. New Subregistry for RPL Rejection Status values . . . . 36 12.6. New Subregistry for RPL Rejection Status values . . . . 37
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 37 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38
14. Normative References . . . . . . . . . . . . . . . . . . . . 37 14. Normative References . . . . . . . . . . . . . . . . . . . . 38
15. Informative References . . . . . . . . . . . . . . . . . . . 38 15. Informative References . . . . . . . . . . . . . . . . . . . 39
Appendix A. Example Compression . . . . . . . . . . . . . . . . 40 Appendix A. Example Compression . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices and low-power lossy transmissions, duty cycling of the LLN devices and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced the "Routing Protocol for Low Power and Lossy The IETF produced the "Routing Protocol for Low Power and Lossy
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let it inject routes in RPL. Using 6LoWPAN ND as opposed to RPL as let it inject routes in RPL. Using 6LoWPAN ND as opposed to RPL as
the host-to-router interface limits the surface of the possible the host-to-router interface limits the surface of the possible
attacks by the RUL against the RPL domain. If all RULs and RANs use attacks by the RUL against the RPL domain. If all RULs and RANs use
6LoWPAN ND for Neighbor Discovery, it is also possible to protect the 6LoWPAN ND for Neighbor Discovery, it is also possible to protect the
address ownership of all nodes, including the RULs. address ownership of all nodes, including the RULs.
This document specifies how the router injects the host routes in the This document specifies how the router injects the host routes in the
RPL domain on behalf of the RUL. Section 5 details how the RUL can RPL domain on behalf of the RUL. Section 5 details how the RUL can
leverage 6LoWPAN ND to obtain the routing services from the router. leverage 6LoWPAN ND to obtain the routing services from the router.
In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-Aware In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-Aware
router is also a 6LoWPAN router (6LR). Using the 6LoWPAN ND Address router is also a 6LoWPAN Router (6LR). Using the 6LoWPAN ND Address
Registration mechanism, the RUL signals that the router must inject a Registration mechanism, the RUL signals that the router must inject a
host route for the Registered Address. host route for the Registered Address.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | <------------- 6LBR / RPL Root | | <------------- 6LBR / RPL Root
+-----+ ^ +-----+ ^
| | | |
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the RULs need to be upgraded. The RPL routers on path will only see the RULs need to be upgraded. The RPL routers on path will only see
unicast IPv6 traffic between the Root and the 6LR. unicast IPv6 traffic between the Root and the 6LR.
This document is organized as follows: This document is organized as follows:
* Section 3 and Section 4 present in a non-normative fashion the * Section 3 and Section 4 present in a non-normative fashion the
salient aspects of RPL and 6LoWPAN ND, respectively, that are salient aspects of RPL and 6LoWPAN ND, respectively, that are
leveraged in this specification to provide connectivity to a 6LN leveraged in this specification to provide connectivity to a 6LN
acting as a RUL across a RPL network. acting as a RUL across a RPL network.
* Section 5 lists the expectations that a RUL needs to match in * Section 5 lists the requirements that a RUL needs to match in
order to be served by a RPL router that complies with this order to be served by a RPL router that complies with this
specification. specification.
* Section 6 presents the changes made to [RFC6550]; a new behavior * Section 6 presents the changes made to [RFC6550]; a new behavior
is introduced whereby the 6LR advertises the 6LN's addresses in a is introduced whereby the 6LR advertises the 6LN's addresses in a
RPL DAO message based on the ND registration by the 6LN, and the RPL DAO message based on the ND registration by the 6LN, and the
RPL root performs the EDAR/EDAC exchange with the 6LBR on behalf RPL root performs the EDAR/EDAC exchange with the 6LoWPAN Border
of the 6LR; modifications are introduced to some RPL options and Router (6LBR) on behalf of the 6LR; modifications are introduced
to the RPL Status to facilitate the integration of the protocols. to some RPL options and to the RPL Status to facilitate the
integration of the protocols.
* Section 7 presents the changes made to [EFFICIENT-NPDAO]; the use * Section 7 presents the changes made to [EFFICIENT-NPDAO]; the use
of the DCO message is extended to the Non-Storing MOP to report of the DCO message is extended to the Non-Storing MOP to report
asynchronous issues from the Root to the 6LR. asynchronous issues from the Root to the 6LR.
* Section 8 presents the changes made to [RFC6775] and [RFC8505]; * Section 8 presents the changes made to [RFC6775] and [RFC8505];
The range of the ND status codes is reduced down to 64 values, and The range of the ND status codes is reduced down to 64 values, and
the remaining bits in the original status field are now reserved. the remaining bits in the original status field are now reserved.
* Section 9 and Section 10 present the operation of this * Section 9 and Section 10 present the operation of this
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DAD: Duplicate Address Detection DAD: Duplicate Address Detection
DAO: Destination Advertisement Object (a RPL message) DAO: Destination Advertisement Object (a RPL message)
DCO: Destination Cleanup Object (a RPL message) DCO: Destination Cleanup Object (a RPL message)
DIO: DODAG Information Object (a RPL message) DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
MOP: RPL Mode of Operation MOP: RPL Mode of Operation
NA: Neighbor Advertisement NA: Neighbor Advertisement
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery ND: Neighbor Discovery
NS: Neighbor solicitation NS: Neighbor Solicitation
RA: router Advertisement RA: router Advertisement
ROVR: Registration Ownership Verifier ROVR: Registration Ownership Verifier
RPI: RPL Packet Information RPI: RPL Packet Information
RAL: RPL-aware Leaf RAL: RPL-aware Leaf
RAN: RPL-Aware Node (either a RPL router or a RPL-aware Leaf) RAN: RPL-Aware Node (either a RPL router or a RPL-aware Leaf)
RUL: RPL-Unaware Leaf RUL: RPL-Unaware Leaf
SRH: Source-Routing Header SRH: Source-Routing Header
TID: Transaction ID (a sequence counter in the EARO) TID: Transaction ID (a sequence counter in the EARO)
TIO: Transit Information Option
2.3. References 2.3. References
The Terminology used in this document is consistent with and The Terminology used in this document is consistent with and
incorporates that described in "Terms Used in Routing for Low-Power incorporates that described in "Terms Used in Routing for Low-Power
and Lossy Networks (LLNs)" [RFC7102]. A glossary of classical and Lossy Networks (LLNs)" [RFC7102]. A glossary of classical
6LoWPAN acronyms is given in Section 2.2. Other terms in use in LLNs 6LoWPAN acronyms is given in Section 2.2. Other terms in use in LLNs
are found in "Terminology for Constrained-Node Networks" [RFC7228]. are found in "Terminology for Constrained-Node Networks" [RFC7228].
This specification uses the terms 6LN and 6LR to refer specifically This specification uses the terms 6LN and 6LR to refer specifically
to nodes that implement the 6LN and 6LR roles in 6LoWPAN ND and does to nodes that implement the 6LN and 6LR roles in 6LoWPAN ND and does
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abstract information that RPL defines to be placed in data packets, abstract information that RPL defines to be placed in data packets,
e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header.
By extension, the term "RPI" is often used to refer to the RPL Option By extension, the term "RPI" is often used to refer to the RPL Option
itself. The Destination Advertisement Object (DAO) and DODAG itself. The Destination Advertisement Object (DAO) and DODAG
Information Object (DIO) messages are also specified in [RFC6550]. Information Object (DIO) messages are also specified in [RFC6550].
The Destination Cleanup Object (DCO) message is defined in The Destination Cleanup Object (DCO) message is defined in
[EFFICIENT-NPDAO]. [EFFICIENT-NPDAO].
This document uses the terms RPL-Unaware Leaf (RUL), RPL-Aware Node This document uses the terms RPL-Unaware Leaf (RUL), RPL-Aware Node
(RAN) and RPL aware Leaf (RAL) consistently with [USEofRPLinfo]. A (RAN) and RPL aware Leaf (RAL) consistently with [USEofRPLinfo]. A
RAN is either an RAL or a RPL router. As opposed to a RUL, a RAN RAN is either a RAL or a RPL router. As opposed to a RUL, a RAN
manages the reachability of its addresses and prefixes by injecting manages the reachability of its addresses and prefixes by injecting
them in RPL by itself. them in RPL by itself.
In this document, readers will encounter terms and concepts that are In this document, readers will encounter terms and concepts that are
discussed in the following documents: discussed in the following documents:
Classical IPv6 ND: "Neighbor Discovery for IP version 6" [RFC4861] Classical IPv6 ND: "Neighbor Discovery for IP version 6" [RFC4861]
and "IPv6 Stateless Address Autoconfiguration" [RFC4862], and "IPv6 Stateless Address Autoconfiguration" [RFC4862],
6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power 6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power
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and and
6LoWPAN ND: Neighbor Discovery Optimization for Low-Power and Lossy 6LoWPAN ND: Neighbor Discovery Optimization for Low-Power and Lossy
Networks [RFC6775], "Registration Extensions for 6LoWPAN Neighbor Networks [RFC6775], "Registration Extensions for 6LoWPAN Neighbor
Discovery" [RFC8505], "Address Protected Neighbor Discovery for Discovery" [RFC8505], "Address Protected Neighbor Discovery for
Low-power and Lossy Networks" [RFC8928], and "IPv6 Backbone Low-power and Lossy Networks" [RFC8928], and "IPv6 Backbone
Router" [RFC8929]. Router" [RFC8929].
3. RPL External Routes and Dataplane Artifacts 3. RPL External Routes and Dataplane Artifacts
Section 4.1 of [USEofRPLinfo] provides a set of rules summarized RPL was initially designed to build stub networks whereby the only
below that must be followed for routing packets from and to a RUL. border router would be the RPL Root (typically collocated with the
6LBR) and all the nodes in the stub would be RPL-Aware. But
[RFC6550] was also prepared to be extended for external routes
(targets in RPL parlance) with the External 'E' flag in the Transit
Information Option (TIO). External targets enable to reach
destinations that are outside the RPL domain and connected to the RPL
domain via RPL border routers that are not the Root. Section 4.1 of
[USEofRPLinfo] provides a set of rules summarized below that must be
followed for routing packets to and from an external destination. A
RUL is a special case of an external target that is also a host
directly connected to the RPL domain.
A 6LR that acts as a border router for external routes advertises A 6LR that acts as a border router for external routes advertises
them using Non-Storing Mode DAO messages that are unicast directly to them using Non-Storing Mode DAO messages that are unicast directly to
the Root, even if the DODAG is operated in Storing Mode. Non-Storing the Root, even if the DODAG is operated in Storing Mode. Non-Storing
Mode routes are not visible inside the RPL domain and all packets are Mode routes are not visible inside the RPL domain and all packets are
routed via the Root. The RPL Root tunnels the packets directly to routed via the Root. The RPL Root tunnels the data packets directly
the 6LR that advertised the external route, which decapsulates and to the 6LR that advertised the external route, which decapsulates and
forwards the original (inner) packet. forwards the original (inner) packets.
The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6 The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6
encapsulated packets appear as normal traffic to the intermediate encapsulated packets appear as normal traffic to the intermediate
routers. The support of external routes only impacts the Root and routers. The support of external routes only impacts the Root and
the 6LR. It can be operated with legacy intermediate routers and the 6LR. It can be operated with legacy intermediate routers and
does not add to the amount of state that must be maintained in those does not add to the amount of state that must be maintained in those
routers. A RUL is an example of a destination that is reachable via routers. A RUL is an example of a destination that is reachable via
an external route that happens to be also a host route. an external route that happens to be also a host route.
The RPL data packets typically carry a Hop-by-Hop Header with a RPL The RPL data packets typically carry a Hop-by-Hop Header with a RPL
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"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
adapts IPv6 ND for operations over energy-constrained LLNs. The main adapts IPv6 ND for operations over energy-constrained LLNs. The main
functions of [RFC6775] are to proactively establish the Neighbor functions of [RFC6775] are to proactively establish the Neighbor
Cache Entry (NCE) in the 6LR and to prevent address duplication. To Cache Entry (NCE) in the 6LR and to prevent address duplication. To
that effect, [RFC6775] introduces a new unicast Address Registration that effect, [RFC6775] introduces a new unicast Address Registration
mechanism that contributes to reducing the use of multicast messages mechanism that contributes to reducing the use of multicast messages
compared to the classical IPv6 ND protocol. compared to the classical IPv6 ND protocol.
[RFC6775] defines a new Address Registration Option (ARO) that is [RFC6775] defines a new Address Registration Option (ARO) that is
carried in the unicast Neighbor solicitation (NS) and Neighbor carried in the unicast Neighbor 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). It also defines the Duplicate Address Request 6LoWPAN router (6LR). It also defines the Duplicate Address Request
(DAR) and Duplicate Address Confirmation (DAC) messages between the (DAR) and Duplicate Address Confirmation (DAC) messages between the
6LR and the 6LoWPAN Border router (6LBR). In an LLN, the 6LBR is the 6LR and the 6LBR). In an LLN, the 6LBR is the central repository of
central repository of all the Registered Addresses in its domain and all the Registered Addresses in its domain and the source of truth
the source of truth for uniqueness and ownership. for uniqueness and ownership.
4.2. RFC 8505 Extended Address Registration 4.2. RFC 8505 Extended Address Registration
"Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505] "Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505]
updates RFC 6775 into a generic Address Registration mechanism that updates RFC 6775 into a generic Address Registration mechanism that
can be used to access services such as routing and ND proxy. To that can be used to access services such as routing and ND proxy. To that
effect, [RFC8505] defines the Extended Address Registration Option effect, [RFC8505] defines the Extended Address Registration Option
(EARO), shown in Figure 2: (EARO), shown in Figure 2:
0 1 2 3 0 1 2 3
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[RFC8505] introduces the R Flag in the EARO. The Registering Node [RFC8505] introduces the R Flag in the EARO. The Registering Node
sets the R Flag to indicate whether the 6LR should ensure sets the R Flag to indicate whether the 6LR should ensure
reachability for the Registered Address. If the R Flag is set to 0, reachability for the Registered Address. If the R Flag is set to 0,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means. In a RPL network, this means that either it Address by other means. In a RPL network, this means that either it
is a RAN that injects the route by itself or that it uses another RPL is a RAN that injects the route by itself or that it uses another RPL
router for reachability services. router for reachability services.
This document specifies how the R Flag is used in the context of RPL. This document specifies how the R Flag is used in the context of RPL.
A RPL leaf that implements the 6LN functionality in [RFC8505] A RPL leaf that implements the 6LN functionality from [RFC8505]
requires reachability services for an IPv6 address if and only if it requires reachability services for an IPv6 address if and only if it
sets the R Flag in the NS(EARO) used to register the address to a 6LR sets the R Flag in the NS(EARO) used to register the address to a 6LR
acting as a RPL border router. Upon receiving the NS(EARO), the RPL acting as a RPL border router. Upon receiving the NS(EARO), the RPL
router generates a DAO message for the Registered Address if and only router generates a DAO message for the Registered Address if and only
if the R flag is set to 1. if the R flag is set to 1.
Section 9.2 specifies additional operations when R flag is set to 1 Section 9.2 specifies additional operations when R flag is set to 1
in an EARO that is placed either in an NS or an NA message. in an EARO that is placed either in an NS or an NA message.
4.2.2. TID, "I" Field and Opaque Fields 4.2.2. TID, "I" Field and Opaque Fields
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To obtain routing services from a router that implements this To obtain routing services from a router that implements this
specification, a RUL needs to implement [RFC8505] and sets the "R" specification, a RUL needs to implement [RFC8505] and sets the "R"
and "T" flags in the EARO to 1 as discussed in Section 4.2.1 and and "T" flags in the EARO to 1 as discussed in Section 4.2.1 and
Section 4.2.2, respectively. Section 9.2.1 specifies new behaviors Section 4.2.2, respectively. Section 9.2.1 specifies new behaviors
for the RUL, e.g., when the R Flag set to 1 in a NS(EARO) is not for the RUL, e.g., when the R Flag set to 1 in a NS(EARO) is not
echoed in the NA(EARO), which indicates that the route injection echoed in the NA(EARO), which indicates that the route injection
failed. failed.
The RUL is expected to request routing services from a router only if The RUL is expected to request routing services from a router only if
that router originates RA messages with a CIO that has the L, P, and that router originates RA messages with a 6CIO that has the L, P, and
E flags all set to 1 as discussed in Section 4.3.1, unless configured E flags all set to 1 as discussed in Section 4.3.1, unless configured
to do so. It is suggested that the RUL also implements [RFC8928] to to do so. It is suggested that the RUL also implements [RFC8928] to
protect the ownership of its addresses. protect the ownership of its addresses.
A RUL that may attach to multiple 6LRs is expected to prefer those A RUL that may attach to multiple 6LRs is expected to prefer those
that provide routing services. The RUL needs to register to all the that provide routing services. The RUL needs to register to all the
6LRs from which it desires routing services. 6LRs from which it desires routing services.
Parallel Address Registrations to several 6LRs should be performed in Parallel Address Registrations to several 6LRs should be performed in
a rapid sequence, using the same EARO for the same Address. Gaps a rapid sequence, using the same EARO for the same Address. Gaps
skipping to change at page 13, line 34 skipping to change at page 14, line 14
5.2. Support of IPv6 Encapsulation 5.2. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either
to the final destination (e.g., a RUL) or to its attachment router to the final destination (e.g., a RUL) or to its attachment router
(designated as 6LR). In order to terminate the IPv6-in-IPv6 tunnel, (designated as 6LR). In order to terminate the IPv6-in-IPv6 tunnel,
the RUL, as an IPv6 host, would have to be capable of decapsulating the RUL, as an IPv6 host, would have to be capable of decapsulating
the tunneled packet and either drop the encapsulated packet if it is the tunneled packet and either drop the encapsulated packet if it is
not the final destination, or pass it to the upper layer for further not the final destination, or pass it to the upper layer for further
processing. As indicated in section 4.1 of [USEofRPLinfo], this is processing. As indicated in section 4.1 of [USEofRPLinfo], this is
not mandated by [RFC8504], so the Root typically terminates the IPv6- not mandated by [RFC8504], and the IPv6-in-IPv6 tunnel from the Root
in-IPv6 tunnel at the parent 6LR. It is thus not necessary for a RUL is terminated at the parent 6LR. It is thus not necessary for a RUL
to support IPv6-in-IPv6 decapsulation. to support IPv6-in-IPv6 decapsulation.
5.3. Support of the Hop-by-Hop Header 5.3. Support of the Hop-by-Hop Header
A RUL is expected to process an Option Type in a Hop-by-Hop Header as A RUL is expected to process an Option Type in a Hop-by-Hop Header as
prescribed by section 4.2 of [RFC8200]. An RPI with an Option Type prescribed by section 4.2 of [RFC8200]. An RPI with an Option Type
of 0x23 [USEofRPLinfo] is thus skipped when not recognized. of 0x23 [USEofRPLinfo] is thus skipped when not recognized.
5.4. Support of the Routing Header 5.4. Support of the Routing Header
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the DODAG Configuration Option (counting from bit 0 as the most the DODAG Configuration Option (counting from bit 0 as the most
significant bit) and it is set to 0 in legacy implementations as significant bit) and it is set to 0 in legacy implementations as
specified respectively in Sections 20.14 and 6.7.6 of [RFC6550]. specified respectively in Sections 20.14 and 6.7.6 of [RFC6550].
The 'P' flag is set to 1 to indicate that the Root performs the proxy The 'P' flag is set to 1 to indicate that the Root performs the proxy
operation, which implies that it supports this specification and the operation, which implies that it supports this specification and the
updated RPL Target Option (see Section 6.1). updated RPL Target Option (see Section 6.1).
Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the
definition of the Flags applies to Mode of Operation (MOP) values definition of the Flags applies to Mode of Operation (MOP) values
zero (0) to six (6) only. For a MOP value of 7, the implementation from zero (0) to six (6) only. For a MOP value of 7, the
MUST consider that the Root performs the proxy operation. implementation MUST consider that the Root performs the proxy
operation.
The RPL DODAG Configuration Option is typically placed in a DODAG The RPL DODAG Configuration Option is typically placed in a DODAG
Information Object (DIO) message. The DIO message propagates down Information Object (DIO) message. The DIO message propagates down
the DODAG to form and then maintain its structure. The DODAG the DODAG to form and then maintain its structure. The DODAG
Configuration Option is copied unmodified from parents to children. Configuration Option is copied unmodified from parents to children.
[RFC6550] states that "Nodes other than the DODAG Root MUST NOT [RFC6550] states that "Nodes other than the DODAG Root MUST NOT
modify this information when propagating the DODAG Configuration modify this information when propagating the DODAG Configuration
option". Therefore, a legacy parent propagates the 'P' Flag as set option". Therefore, a legacy parent propagates the 'P' Flag as set
by the Root, and when the 'P' Flag is set to 1, it is transparently by the Root, and when the 'P' Flag is set to 1, it is transparently
flooded to all the nodes in the DODAG. flooded to all the nodes in the DODAG.
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The 6LoWPAN ND Status was defined for use in the EARO, see section The 6LoWPAN ND Status was defined for use in the EARO, see section
4.1 of [RFC8505]. This specification adds a capability to allow the 4.1 of [RFC8505]. This specification adds a capability to allow the
carriage of 6LoWPAN ND Status values in RPL DAO and DCO messages, carriage of 6LoWPAN ND Status values in RPL DAO and DCO messages,
embedded in the RPL Status field. embedded in the RPL Status field.
To achieve this, the range of the ARO/EARO Status values is reduced To achieve this, the range of the ARO/EARO Status values is reduced
to 0-63, which updates the IANA registry created for [RFC6775]. This to 0-63, which updates the IANA registry created for [RFC6775]. This
reduction ensures that the values fit within a RPL Status as shown in reduction ensures that the values fit within a RPL Status as shown in
Figure 6. See Section 12.2, Section 12.5, and Section 12.6 for the Figure 6. See Section 12.2, Section 12.5, and Section 12.6 for the
respective IANA declarations. respective IANA declarations. This ask is reasonable because the
associated registry relies on standards action for registration and
only values up to 10 are currently allocated.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|A|StatusValue| |E|A|StatusValue|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 6: RPL Status Format Figure 6: RPL Status Format
This specification updates the RPL Status with subfields as indicated This specification updates the RPL Status with subfields as indicated
below: below:
skipping to change at page 19, line 21 skipping to change at page 20, line 9
Reciprocally, upon a DCO or a DAO-ACK message from the RPL Root with Reciprocally, upon a DCO or a DAO-ACK message from the RPL Root with
a RPL Status that has the 'A' flag set, the 6LR MUST copy the RPL a RPL Status that has the 'A' flag set, the 6LR MUST copy the RPL
Status value unchanged in the Status field of the EARO when Status value unchanged in the Status field of the EARO when
generating an NA to the RUL. generating an NA to the RUL.
7. Enhancements to draft-ietf-roll-efficient-npdao 7. Enhancements to draft-ietf-roll-efficient-npdao
[EFFICIENT-NPDAO] defines the DCO message for RPL Storing Mode only, [EFFICIENT-NPDAO] defines the DCO message for RPL Storing Mode only,
with a link-local scope. All nodes in the RPL network are expected with a link-local scope. All nodes in the RPL network are expected
to support the specification since the message is processed hop by to support the specification since the message is processed hop-by-
hop along the path that is being cleaned up. hop along the path that is being cleaned up.
This specification extends the use of the DCO message to the Non- This specification extends the use of the DCO message to the Non-
Storing MOP, whereby the DCO is sent end-to-end by the Root directly Storing MOP, whereby the DCO is sent end-to-end by the Root directly
to the RAN that injected the DAO message for the considered target. to the RAN that injected the DAO message for the considered target.
In that case, intermediate nodes do not need to support In that case, intermediate nodes do not need to support
[EFFICIENT-NPDAO]; they forward the DCO message as a plain IPv6 [EFFICIENT-NPDAO]; they forward the DCO message as a plain IPv6
packet between the Root and the RAN. packet between the Root and the RAN.
In the case of a RUL, the 6LR that serves the RUL acts as the RAN In the case of a RUL, the 6LR that serves the RUL acts as the RAN
that receives the Non-Storing DCO. This specification leverages the that receives the Non-Storing DCO. This specification leverages the
Non-Storing DCO between the Root and the 6LR that serves as Non-Storing DCO between the Root and the 6LR that serves as
attachment router for a RUL. A 6LR and a Root that support this attachment router for a RUL. A 6LR and a Root that support this
specification MUST implement the Non-Storing DCO. specification MUST implement the Non-Storing DCO.
8. Enhancements to RFC 6775 and RFC8505 8. Enhancements to RFC6775 and RFC8505
This document updates [RFC6775] and [RFC8505] to reduce the range of This document updates [RFC6775] and [RFC8505] to reduce the range of
the ND status codes down to 64 values. The two most significant the ND status codes down to 64 values. The two most significant
(leftmost) bits if the original ND status field are now reserved, (leftmost) bits if the original ND status field are now reserved,
they MUST be set to zero by the sender and ignored by the receiver. they MUST be set to zero by the sender and ignored by the receiver.
This document also changes the behavior of a 6LR acting as RPL router This document also updates the behavior of a 6LR acting as RPL router
and of a 6LN acting as RUL in the 6LoWPAN ND Address Registration as and of a 6LN acting as RUL in the 6LoWPAN ND Address Registration as
follows: follows:
* If the RPL Root advertises the capability to proxy the EDAR/EDAC * If the RPL Root advertises the capability to proxy the EDAR/EDAC
exchange to the 6LBR, the 6LR refrains from sending the keep-alive exchange to the 6LBR, the 6LR refrains from sending the keep-alive
EDAR message. If it is separated from the 6LBR, the Root EDAR message. If it is separated from the 6LBR, the Root
regenerates the EDAR message to the 6LBR periodically, upon a DAO regenerates the EDAR message to the 6LBR periodically, upon a DAO
message that signals the liveliness of the address. message that signals the liveliness of the address.
* The use of the R Flag is extended to the NA(EARO) to confirm * The use of the R Flag is extended to the NA(EARO) to confirm
skipping to change at page 26, line 27 skipping to change at page 27, line 6
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is signaled as the Target Prefix in the 1. The Registered Address is signaled as the Target Prefix in the
updated Target Option in the DAO message; the Prefix Length is updated Target Option in the DAO message; the Prefix Length is
set to 128 but the 'F' flag is set to 0 since the advertiser is set to 128 but the 'F' flag is set to 0 since the advertiser is
not the RUL. The ROVR field is copied unchanged from the EARO not the RUL. The ROVR field is copied unchanged from the EARO
(see Section 6.1). (see Section 6.1).
2. The 6LR indicates one of its global or unique-local IPv6 unicast 2. The 6LR indicates one of its global or unique-local IPv6 unicast
addresses as the Parent Address in the RPL Transit Information addresses as the Parent Address in the TIO associated with the
Option (TIO) associated with the Target Option Target Option
3. The 6LR sets the External 'E' flag in the TIO to indicate that it 3. The 6LR sets the External 'E' flag in the TIO to indicate that it
is redistributing an external target into the RPL network is redistributing an external target into the RPL network
4. the Path Lifetime in the TIO is computed from the Registration 4. The Path Lifetime in the TIO is computed from the Registration
Lifetime in the EARO. This operation converts seconds to the Lifetime in the EARO. This operation converts seconds to the
Lifetime Units used in the RPL operation. This creates the Lifetime Units used in the RPL operation. This creates the
deployment constraint that the Lifetime Unit is reasonably deployment constraint that the Lifetime Unit is reasonably
compatible with the expression of the Registration Lifetime. compatible with the expression of the Registration Lifetime;
e.g., a Lifetime Unit of 0x4000 maps the most significant byte of e.g., a Lifetime Unit of 0x4000 maps the most significant byte of
the Registration Lifetime to the Path Lifetime. the Registration Lifetime to the Path Lifetime.
In that operation, the Path Lifetime must be rounded, if needed, In that operation, the Path Lifetime must be rounded, if needed,
to the upper value to ensure that the path has a longer lifetime to the upper value to ensure that the path has a longer lifetime
than the registration. than the registration.
Note that if the Registration Lifetime is 0, then the Path Note that if the Registration Lifetime is 0, then the Path
Lifetime is also 0 and the DAO message becomes a No-Path DAO, Lifetime is also 0 and the DAO message becomes a No-Path DAO,
which cleans up the routes down to the RUL's address; this also which cleans up the routes down to the RUL's address; this also
skipping to change at page 27, line 18 skipping to change at page 27, line 46
MUST send an asynchronous NA(EARO) to the RUL immediately, but still MUST send an asynchronous NA(EARO) to the RUL immediately, but still
be capable of processing the DAO-ACK if one is pending. be capable of processing the DAO-ACK if one is pending.
The 6LR MUST set the R Flag to 1 in the NA(EARO) back if and only if The 6LR MUST set the R Flag to 1 in the NA(EARO) back if and only if
the 'E' flag in the RPL Status is set to 0, indicating that the 6LR the 'E' flag in the RPL Status is set to 0, indicating that the 6LR
injected the Registered Address in the RPL routing successfully and injected the Registered Address in the RPL routing successfully and
that the EDAR proxy operation succeeded. that the EDAR proxy operation succeeded.
If the 'A' flag in the RPL Status is set to 1, the embedded Status If the 'A' flag in the RPL Status is set to 1, the embedded Status
value is passed back to the RUL in the EARO Status. If the 'E' flag value is passed back to the RUL in the EARO Status. If the 'E' flag
is also set to 1, the registration failed for 6LoWPAN ND related is also set to 1, the registration failed for 6LoWPAN-ND-related
reasons, and the NCE is removed. reasons, and the NCE is removed.
An error injecting the route causes the 'E' flag to be set to 1. If An error injecting the route causes the 'E' flag to be set to 1. If
the error is not related to ND, the 'A' flag is set to 0. In that the error is not related to ND, the 'A' flag is set to 0. In that
case, the registration succeeds, but the RPL route is not installed. case, the registration succeeds, but the RPL route is not installed.
So the NA(EARO) is returned with a status indicating success but the So the NA(EARO) is returned with a status indicating success but the
R Flag set to 0, which means that the 6LN obtained a binding but no R Flag set to 0, which means that the 6LN obtained a binding but no
route. route.
If the 'A' flag is set to 0 in the RPL Status of the DAO-ACK, then If the 'A' flag is set to 0 in the RPL Status of the DAO-ACK, then
skipping to change at page 30, line 5 skipping to change at page 31, line 5
The EDAR message MUST be constructed as follows: The EDAR message MUST be constructed as follows:
1. The Target IPv6 address from the RPL Target Option is placed in 1. The Target IPv6 address from the RPL Target Option is placed in
the Registered Address field of the EDAR message; the Registered Address field of the EDAR message;
2. the Registration Lifetime is adapted from the Path Lifetime in 2. the Registration Lifetime is adapted from the Path Lifetime in
the TIO by converting the Lifetime Units used in RPL into units the TIO by converting the Lifetime Units used in RPL into units
of 60 seconds used in the 6LoWPAN ND messages; of 60 seconds used in the 6LoWPAN ND messages;
3. the TID value is set to the Path Sequence in the TIO and 3. The TID value is set to the Path Sequence in the TIO and
indicated with an ICMP code of 1 in the EDAR message; indicated with an ICMP code of 1 in the EDAR message;
4. The ROVR in the RPL Target Option is copied as is in the EDAR and 4. The ROVR in the RPL Target Option is copied as is in the EDAR and
the ICMP Code Suffix is set to the appropriate value as shown in the ICMP Code Suffix is set to the appropriate value as shown in
Table 4 of [RFC8505] depending on the size of the ROVR field. Table 4 of [RFC8505] depending on the size of the ROVR field.
Upon receiving an EDAC message from the 6LBR, if a DAO is pending, Upon receiving an EDAC message from the 6LBR, if a DAO is pending,
then the Root MUST send a DAO-ACK back to the 6LR. Otherwise, if the then the Root MUST send a DAO-ACK back to the 6LR. Otherwise, if the
Status in the EDAC message is not "Success", then it MUST send an Status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. asynchronous DCO to the 6LR.
skipping to change at page 33, line 38 skipping to change at page 34, line 38
well. well.
The Link-Layer security is needed in particular to prevent Denial-Of- The Link-Layer security is needed in particular to prevent Denial-Of-
Service attacks whereby a rogue 6LN creates a high churn in the RPL Service attacks whereby a rogue 6LN creates a high churn in the RPL
network by constantly registering and deregistering addresses with network by constantly registering and deregistering addresses with
the R Flag set to 1 in the EARO. the R Flag set to 1 in the EARO.
[RFC8928] updated 6LoWPAN ND with the called Address-Protected [RFC8928] updated 6LoWPAN ND with the called Address-Protected
Neighbor Discovery (AP-ND). AP-ND protects the owner of an address Neighbor Discovery (AP-ND). AP-ND protects the owner of an address
against address theft and impersonation attacks in a Low-Power and against address theft and impersonation attacks in a Low-Power and
Lossy Network (LLN). Nodes supporting th extension compute a Lossy Network (LLN). Nodes supporting the extension compute a
cryptographic identifier (Crypto-ID), and use it with one or more of cryptographic identifier (Crypto-ID), and use it with one or more of
their Registered Addresses. The Crypto-ID identifies the owner of their Registered Addresses. The Crypto-ID identifies the owner of
the Registered Address and can be used to provide proof of ownership the Registered Address and can be used to provide proof of ownership
of the Registered Addresses. Once an address is registered with the of the Registered Addresses. Once an address is registered with the
Crypto-ID and a proof of ownership is provided, only the owner of Crypto-ID and a proof of ownership is provided, only the owner of
that address can modify the registration information, thereby that address can modify the registration information, thereby
enforcing Source Address Validation. [RFC8928] reduces even more the enforcing Source Address Validation. [RFC8928] reduces even more the
attack perimeter that is available to the edge nodes and its use is attack perimeter that is available to the edge nodes and its use is
suggested in this specification. suggested in this specification.
skipping to change at page 35, line 30 skipping to change at page 36, line 30
Option Flags for MOP 0..6" [USEofRPLinfo] registry as follows: Option Flags for MOP 0..6" [USEofRPLinfo] registry as follows:
+---------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+---------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
| 1 (suggested) | Root Proxies EDAR/EDAC (P) | THIS RFC | | 1 (suggested) | Root Proxies EDAR/EDAC (P) | THIS RFC |
+---------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
Table 2: New DODAG Configuration Option Flag Table 2: New DODAG Configuration Option Flag
IANA is requested to add [this document] as a reference for MOP 7 in
the RPL Mode of Operation registry.
12.4. RPL Target Option Registry 12.4. RPL Target Option Registry
This document modifies the "RPL Target Option Flags" registry This document modifies the "RPL Target Option Flags" registry
initially created in Section 20.15 of [RFC6550] . The registry now initially created in Section 20.15 of [RFC6550] . The registry now
includes only 4 bits (Section 6.1) and should point to this document includes only 4 bits (Section 6.1) and should point to this document
as an additional reference. The registration procedure doesn't as an additional reference. The registration procedure does not
change. change.
Section 6.1 also defines 2 new entries in the Registry as follows: Section 6.1 also defines 2 new entries in the Registry as follows:
+---------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+---------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
| 0 (suggested) | Advertiser address in Full (F) | THIS RFC | | 0 (suggested) | Advertiser address in Full (F) | THIS RFC |
+---------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
| 1 (suggested) | Proxy EDAR Requested (X) | THIS RFC | | 1 (suggested) | Proxy EDAR Requested (X) | THIS RFC |
skipping to change at page 37, line 10 skipping to change at page 38, line 10
| 1..63 | Unassigned | | | 1..63 | Unassigned | |
+-------+-----------------------+-----------+ +-------+-----------------------+-----------+
Table 5: Rejection values of the RPL Status Table 5: Rejection values of the RPL Status
13. Acknowledgments 13. Acknowledgments
The authors wish to thank Ines Robles, Georgios Papadopoulos and The authors wish to thank Ines Robles, Georgios Papadopoulos and
especially Rahul Jadhav and Alvaro Retana for their reviews and especially Rahul Jadhav and Alvaro Retana for their reviews and
contributions to this document. Also many thanks to Eric Vyncke, contributions to this document. Also many thanks to Eric Vyncke,
Erik Kline, Murray Kucherawy, Peter Van der Stok, Carl Wallace, and Erik Kline, Murray Kucherawy, Peter Van der Stok, Carl Wallace, Barry
especially Benjamin Kaduk and Elwyn Davies, for their reviews and Leiba, Julien Meuric, and especially Benjamin Kaduk and Elwyn Davies,
useful comments during the IETF Last Call and the IESG review for their reviews and useful comments during the IETF Last Call and
sessions. the IESG review sessions.
14. Normative References 14. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810, Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
 End of changes. 36 change blocks. 
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