draft-ietf-roll-unaware-leaves-18.txt   draft-ietf-roll-unaware-leaves-19.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: draft-ietf-roll-efficient-npdao, 6550, M. Richardson Updates: 6550, 8505 (if approved) M. Richardson
8505 (if approved) Sandelman Intended status: Standards Track Sandelman
Intended status: Standards Track 12 June 2020 Expires: 22 March 2021 18 September 2020
Expires: 14 December 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-18 draft-ietf-roll-unaware-leaves-19
Abstract Abstract
This specification extends RFC6550 and RFC8505 to provide routing This specification extends RFC6550 and RFC8505 to provide routing
services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND
but do not participate to RPL. This specification also enables the but do not participate in RPL. This specification also enables the
RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG. RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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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 14 December 2020. This Internet-Draft will expire on 22 March 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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. References . . . . . . . . . . . . . . . . . . . . . . . 6
3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 7 3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 7
3.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 7 4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 8
3.2. RFC 8505 Extended Address Registration . . . . . . . . . 7 4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 8
3.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 8 4.2. RFC 8505 Extended Address Registration . . . . . . . . . 8
3.2.2. TID, I Field and Opaque Fields . . . . . . . . . . . 8 4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.2. TID, I Field and Opaque Fields . . . . . . . . . . . 9
3.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 9 4.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1. RFC 7400 Capability Indication Option . . . . . . . . 9 4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 10
4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 10 4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 10
5. Updating draft-ietf-roll-efficient-npdao . . . . . . . . . . 11 5. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11
6. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 11 5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11
7. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11 5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 11
7.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11 5.3. Support of the HbH Header . . . . . . . . . . . . . . . . 12
7.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12 5.4. Support of the Routing Header . . . . . . . . . . . . . . 12
7.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13 6. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 12
7.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13 6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 13
7.2.3. Support of the Routing Header . . . . . . . . . . . . 13 6.2. Updated DODAG Configuration Option . . . . . . . . . . . 14
8. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13 6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 15
9. Updated RPL Target Option . . . . . . . . . . . . . . . . . . 14 7. Updating draft-ietf-roll-efficient-npdao . . . . . . . . . . 16
10. Protocol Operations for Unicast Addresses . . . . . . . . . . 15 8. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 16
10.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 16 9. Protocol Operations for Unicast Addresses . . . . . . . . . . 16
10.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 18 9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 17
10.2.1. Perspective of the RUL Acting as 6LN . . . . . . . . 18 9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19
10.2.2. Perspective of the Border Router Acting as 6LR . . . 19 9.2.1. Perspective of the RUL Acting as 6LN . . . . . . . . 19
10.2.3. Perspective of the RPL Root . . . . . . . . . . . . 22 9.2.2. Perspective of the Border Router Acting as 6LR . . . 20
10.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . 22 9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 23
11. Protocol Operations for Multicast Addresses . . . . . . . . . 23 9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 23
12. Security Considerations . . . . . . . . . . . . . . . . . . . 24 10. Protocol Operations for Multicast Addresses . . . . . . . . . 24
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
13.1. Fixing the Address Registration Option Flags . . . . . . 25 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
13.2. Resizing the ARO Status values . . . . . . . . . . . . . 25 12.1. Fixing the Address Registration Option Flags . . . . . . 26
14. New DODAG Configuration Option Flag . . . . . . . . . . . . . 26 12.2. Resizing the ARO Status values . . . . . . . . . . . . . 26
15. New RPL Target Option Flag . . . . . . . . . . . . . . . . . 26 12.3. New DODAG Configuration Option Flag . . . . . . . . . . 27
16. New Subregistry for the RPL Non-Rejection Status values . . . 26 12.4. New RPL Target Option Flag . . . . . . . . . . . . . . . 27
17. New Subregistry for the RPL Rejection Status values . . . . . 27 12.5. New Subregistry for the RPL Non-Rejection Status
18. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 values . . . . . . . . . . . . . . . . . . . . . . . . . 27
19. Normative References . . . . . . . . . . . . . . . . . . . . 27 12.6. New Subregistry for the RPL Rejection Status values . . 28
20. Informative References . . . . . . . . . . . . . . . . . . . 29 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28
Appendix A. Example Compression . . . . . . . . . . . . . . . . 31 14. Normative References . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 15. Informative References . . . . . . . . . . . . . . . . . . . 31
Appendix A. Example Compression . . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices and low-power lossy transmissions, duty cycling of the LLN devices and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced the "Routing Protocol for Low Power and Lossy The IETF produced the "Routing Protocol for Low Power and Lossy
Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services
within such constraints. RPL belongs to the class of Distance-Vector within such constraints. RPL belongs to the class of Distance-Vector
protocols, which, compared to link-state protocols, limit the amount protocols, which, compared to link-state protocols, limit the amount
of topological knowledge that needs to be installed and maintained in of topological knowledge that needs to be installed and maintained in
each node, and does not require convergence to avoid micro-loops. each node, and does not require convergence to avoid micro-loops.
To save signaling and routing state in constrained networks, RPL To save signaling and routing state in constrained networks, RPL
allows a routing stretch (see [RFC6687]), whereby routing is only allows a path stretch (see [RFC6687]), whereby routing is only
performed along an acyclic graph optimized to reach a Root node, as performed along a Destination-Oriented Directed Acyclic Graph (DODAG)
opposed to straight along a shortest path between 2 peers, whatever that is optimized to reach a Root node, as opposed to along the
that would mean in a given LLN. This trades the quality of peer-to- shortest path between 2 peers, whatever that would mean in a given
peer (P2P) paths for a vastly reduced amount of control traffic and LLN. This trades the quality of peer-to-peer (P2P) paths for a
routing state that would be required to operate a any-to-any shortest vastly reduced amount of control traffic and routing state that would
path protocol. Finally, broken routes may be fixed lazily and on- be required to operate an any-to-any shortest path protocol.
demand, based on dataplane inconsistency discovery, which avoids Additionally, broken routes may be fixed lazily and on-demand, based
wasting energy in the proactive repair of unused paths. on dataplane inconsistency discovery, which avoids wasting energy in
the proactive repair of unused paths.
To provide alternate paths in lossy networks, RPL forms Destination- For many of the nodes, though not all, the DODAG provides multiple
Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information
solicitation (DIS) and DODAG Information Object (DIO) messages. For
many of the nodes, though not all, a DODAG provides multiple
forwarding solutions towards the Root of the topology via so-called forwarding solutions towards the Root of the topology via so-called
parents. RPL is designed to adapt to fuzzy connectivity, whereby the parents. RPL is designed to adapt to fuzzy connectivity, whereby the
physical topology cannot be expected to reach a stable state, with a physical topology cannot be expected to reach a stable state, with a
lazy control that creates the routes proactively, but may only fix lazy control that creates the routes proactively, but may only fix
them reactively, upon actual traffic. The result is that RPL them reactively, upon actual traffic. The result is that RPL
provides reachability for most of the LLN nodes, most of the time, provides reachability for most of the LLN nodes, most of the time,
but may not converge in the classical sense. but may not converge in the classical sense.
[RFC6550] provides unicast and multicast routing services to RPL- RPL can be deployed in conjunction with IPv6 Neighbor Discovery (ND)
Aware nodes (RANs), either as a collection tree for outwards traffic [RFC4861] [RFC4862] and 6LoWPAN ND [RFC6775] [RFC8505] to maintain
only, or with routing back to the devices as well. In the latter reachability within a Non-Broadcast Multi-Access (NBMA) Multi-Link
case, a RAN injects routes to itself using Destination Advertisement subnet.
Object (DAO) messages sent either to 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) In that mode, IPv6 addresses are advertised individually as Host
[RFC4861][RFC4862] and 6LoWPAN ND [RFC6775][RFC8505] to maintain routes. Some nodes may act as Routers and participate to the
reachability within a Non-Broadcast Multi-Access (NBMA) subnet. In
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, an IPv6 Host
is reachable over the RPL network is called a Leaf. [RFC8504] that is reachable over the RPL network is called a Leaf.
"When to use RFC 6553, 6554 and IPv6-in-IPv6" [USEofRPLinfo] [USEofRPLinfo] introduces the terms RPL-Aware-Leaf (RAL) and RPL-
introduces the term RPL-Aware-Leaf (RAL) for a Leaf that injects Unaware Leaf (RUL). A RAL is a Leaf that injects Host routes in RPL
routes in RPL to manage the reachability of its own IPv6 addresses. to manage the reachability of its IPv6 addresses. Conversely, a RUL
In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf that does not participate to RPL and cannot inject its Host routes in RPL.
does not participate to RPL at all. A RUL is an IPv6 Host [RFC8504] The RUL therefore needs a Host-to-Router interface to advertise its
that needs a RPL-Aware Router to obtain routing services over the RPL IPv6 addresses to its access Router so the Router can inject them the
network. RPL network on its behalf. Section 5 details the interface needed by
a router that implements this specification.
This specification leverages the Address Registration mechanism This specification leverages the Address Registration mechanism
defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to defined in 6LoWPAN ND to enable a RUL acting as a 6LoWPAN Node (6LN)
interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) and to interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) and
request that the 6LR injects a Host route for the Registered Address request that the 6LR injects a Host route for the Registered Address
in the RPL routing on its behalf. A RUL may be unable to participate in the RPL routing on its behalf. A RUL may be unable to participate
because it is very energy-constrained, or because it is unsafe to let because it is very energy-constrained, or because it is unsafe to let
it inject routes in RPL, in which case using 6LowPAN ND as the it inject routes in RPL, in which case using 6LowPAN ND as the
interface for the RUL limits the surface of the possible attacks and interface for the RUL limits the surface of the possible attacks and
optionally protects the address ownership. optionally protects the address ownership.
The RPL Non-Storing Mode mechanism is used to extend the routing The RPL Non-Storing Mode mechanism is used to extend the routing
state with connectivity to the RULs even when the DODAG is operated state with connectivity to the RULs even when the DODAG is operated
in Storing Mode. The unicast packet forwarding operation by the 6LR in Storing Mode. The unicast packet forwarding operation by the 6LR
serving a 6LN that is also a RUL is described in [USEofRPLinfo]. serving a RUL, as described in section 4.1 of [USEofRPLinfo].
Examples of routing-agnostic 6LNs include lightly powered sensors Examples of possible RULs include lightly powered sensors such as
such as window smash sensor (alarm system), and kinetically powered window smash sensor (alarm system), and kinetically powered light
light switches. Other applications of this specification may include switches. Other applications of this specification may include a
a smart grid network that controls appliances - such as washing smart grid network that controls appliances - such as washing
machines or the heating system - in the home. Appliances may not machines or the heating system - in the home. Appliances may not
participate to the RPL protocol operated in the Smartgrid network but participate to the RPL protocol operated in the Smartgrid network but
can still interact with the Smartgrid for control and/or metering. can still interact with the Smartgrid for control and/or metering.
This document is organized as follows:
* Section 3 and Section 4 present salient aspects of RPL and 6LoWPAN
ND, respectively, that are leveraged in this specification to
provide connectivity to a RUL across a RPL network.
* Section 5 lists the expectations that a RUL needs to match in
order to be served by a RPL router that complies with this
specification.
* Section 6, Section 7, and Section 8 present the additions made to
[RFC6550], [EFFICIENT-NPDAO], and [RFC8505].
* Section 9 and Section 10 present the operation of this
specification for unicast and multicast flows, respectively, and
Section 11 presents associated security considerations.
2. Terminology 2. Terminology
2.1. BCP 14 2.1. Requirements Language
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.
2.2. References 2.2. Glossary
This document often uses the following acronyms:
AR: Address Resolution (aka Address Lookup)
ARQ: Automatic Repeat reQuest
6CIO: 6LoWPAN Capability Indication Option
6LN: 6LoWPAN Node (a Low Power Host or Router)
6LR: 6LoWPAN Router
(E)ARO: (Extended) Address Registration Option
(E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection
DAO: Destination Advertisement Object (a RPL message)
DCO: Destination Cleanup Object (a RPL message)
DIS: DODAG Information solicitation (a RPL message)
DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement
NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NS: Neighbor solicitation
RA: Router Advertisement
ROVR: Registration Ownership Verifier
RPI: RPL Packet Information
RAL: RPL-Aware Leaf
RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf)
RUL: RPL-Unaware Leaf
TID: Transaction ID (a sequence counter in the EARO)
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 2.3. 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
to nodes that implement the 6LN and 6LR roles in 6LoWPAN ND and does
not expect other functionality such as 6LoWPAN Header Compression
[RFC6282] from those nodes.
"RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by "RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by
a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract
information that RPL defines to be placed in data packets, e.g., as information that RPL defines to be placed in data packets, e.g., as
the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By
extension the term "RPI" is often used to refer to the RPL Option extension, the term "RPI" is often used to refer to the RPL Option
itself. The DODAG Information solicitation (DIS), Destination itself. The DODAG Information solicitation (DIS), Destination
Advertisement Object (DAO) and DODAG Information Object (DIO) Advertisement Object (DAO) and DODAG Information Object (DIO)
messages are also specified in [RFC6550]. The Destination Cleanup messages are also specified in [RFC6550]. The Destination Cleanup
Object (DCO) message is defined in [EFFICIENT-NPDAO]. Object (DCO) message is defined in [EFFICIENT-NPDAO].
This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware
Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node
(RAN) is introduced to refer to a node that is either an RAL or a RPL (RAN) is introduced to refer to a node that is either an RAL or a RPL
Router. As opposed to a RUL, a RAN manages the reachability of its Router. As opposed to a RUL, a RAN manages the reachability of its
addresses and prefixes by injecting them in RPL by itself. addresses and prefixes by injecting them in RPL by itself.
skipping to change at page 5, line 45 skipping to change at page 6, line 49
6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power 6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606] and Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606] and
"IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals" [RFC4919], Overview, Assumptions, Problem Statement, and Goals" [RFC4919],
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], and "Address Protected Neighbor Discovery Discovery" [RFC8505], and "Address Protected Neighbor Discovery
for Low-power and Lossy Networks" [AP-ND] . for Low-power and Lossy Networks" [AP-ND].
2.3. Glossary
This document often uses the following acronyms:
AR: Address Resolution (aka Address Lookup)
6CIO: 6LoWPAN Capability Indication Option
6LN: 6LoWPAN Node (a Low Power Host or Router)
6LR: 6LoWPAN Router
(E)ARO: (Extended) Address Registration Option
(E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection
DAO: Destination Advertisement Object (a RPL message)
DCO: Destination Cleanup Object (a RPL message)
DIS: DODAG Information solicitation (a RPL message)
DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement
NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NS: Neighbor solicitation 3. RPL External Routes and Dataplane Artifacts
RA: Router Advertisement Section 4.1 of [USEofRPLinfo] provides a set of rules detailed below
that MUST be followed for routing packets from and to a RUL.
ROVR: Registration Ownership Verifier A 6LR that acts as a border Router for external routes advertises
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
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
the 6LR that advertised the external route, which decapsulates and
forwards the original (inner) packet.
RPI: RPL Packet Information The RPL Non-Storing MOP signaling and the associated IP-in-IP
encapsulated packets appear as normal traffic to the intermediate
Routers. The support of external routes only impacts the Root 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
Routers. A RUL is an example of a destination that is reachable via
an external route that happens to be also a Host route.
RAL: RPL-Aware Leaf The RPL data packets always carry a Hop-by-Hop Header to transport a
RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates
its packets with an RPI, the 6LR needs to tunnel them to the Root to
add the RPI. As a rule of a thumb and except for the very special
case above, the packets from and to a RUL are always encapsulated
using an IP-in-IP tunnel between the Root and the 6LR that serves the
RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4,
8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details).
RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf) In Non-Storing Mode, packets going down carry a Source Routing Header
(SRH). The IP-in-IP encapsulation, the RPI and the SRH are
collectively called the "RPL artifacts" and can be compressed using
[RFC8138]. Figure 11 presents an example compressed format for a
packet forwarded by the Root to a RUL in a Storing Mode DODAG.
RUL: RPL-Unaware Leaf The inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it,
and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the
RUL to support the basic "IPv6 Node Requirements" [RFC8504]. In
particular the RUL is expected to ignore the RPL artifacts that are
either consumed or not applicable to a Host.
TID: Transaction ID (a sequence counter in the EARO) A RUL is not expected to support the compression method defined in
[RFC8138]. Unless configured otherwise, the border Router MUST
restore the outgoing packet before forwarding over an external route,
even if it is not the destination of the incoming packet, and even
when delivering to a RUL.
3. 6LoWPAN Neighbor Discovery 4. 6LoWPAN Neighbor Discovery
3.1. RFC 6775 Address Registration 4.1. RFC 6775 Address Registration
The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861] The classic "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861]
[RFC4862] was defined for serial links and transit media such as [RFC4862] was defined for serial links and transit media such as
Ethernet. It is a reactive protocol that relies heavily on multicast Ethernet. It is a reactive protocol that relies heavily on multicast
operations for address discovery (aka lookup) and duplicate address operations for address discovery (aka lookup) and duplicate address
detection (DAD). detection (DAD).
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
adapts IPv6 ND for operations over energy-constrained LLNs. The main adapts IPv6 ND for operations over energy-constrained LLNs. The main
functions of [RFC6775] are to proactively establish the Neighbor functions of [RFC6775] are to proactively establish the Neighbor
Cache Entry (NCE) in the 6LR and to prevent address duplication. To Cache Entry (NCE) in the 6LR and to prevent address duplication. To
that effect, [RFC6775] introduces a new unicast Address Registration that effect, [RFC6775] introduces a new unicast Address Registration
skipping to change at page 7, line 32 skipping to change at page 8, line 32
[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 6LoWPAN Border Router (6LBR). In an LLN, the 6LBR is the
central repository of all the Registered Addresses in its domain and central repository of all the Registered Addresses in its domain and
the source of truth for uniqueness and ownership. the source of truth for uniqueness and ownership.
3.2. RFC 8505 Extended Address Registration 4.2. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd | I |R|T| TID | Registration Lifetime | | Rsvd | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier ... ... Registration Ownership Verifier ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Option Format Figure 1: EARO Option Format
3.2.1. R Flag 4.2.1. R Flag
[RFC8505] introduces the "R" flag in the EARO. The Registering Node [RFC8505] introduces the "R" flag in the EARO. The Registering Node
sets the "R" flag to indicate whether the 6LR should ensure sets the "R" flag to indicate whether the 6LR should ensure
reachability for the Registered Address. If the "R" flag is not set, reachability for the Registered Address. If the "R" flag is not set,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means. 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 This document specifies how the "R" flag is used in the context of
RPL. A 6LN is a RUL that requires reachability services for an IPv6 RPL. A RPL Leaf that implements the 6LN functionality in [RFC8505]
address if and only if it sets the "R" flag in the NS(EARO) used to requires reachability services for an IPv6 address if and only if it
register the address to a RPL border router acting as 6LR. Upon sets the "R" flag in the NS(EARO) used to register the address to a
receiving the NS(EARO), the RPL router generates a DAO message for RPL border Router acting as 6LR. Upon receiving the NS(EARO), the
the Registered Address if and only if the "R" flag is set. RPL Router generates a DAO message for the Registered Address if and
only if the "R" flag is set. More in Section 9.2.
3.2.2. TID, I Field and Opaque Fields 4.2.2. TID, I Field and Opaque Fields
When the "T" flag is set, the EARO includes a sequence counter called When the "T" flag is set, the EARO includes a sequence counter called
Transaction ID (TID), which maps to the Path Sequence Field found in Transaction ID (TID), that is needed to fill the Path Sequence Field
the RPL Transit Option. This is the reason why the support of in the RPL Transit Option. This is the reason why the support of
[RFC8505] by the RUL as opposed to only [RFC6775] is a prerequisite [RFC8505] by the RUL, as opposed to only [RFC6775] is a prerequisite
for this specification (more in Section 7.1). The EARO also for this specification (more in Section 5.1). The EARO also
transports an Opaque field and an associated "I" field that describes transports an Opaque field and an associated "I" field that describes
what the Opaque field transports and how to use it. Section 10.2.1 what the Opaque field transports and how to use it. Section 9.2.1
specifies the use of the "I" field and of the Opaque field by a RUL. specifies the use of the "I" field and the Opaque field by a RUL.
3.2.3. ROVR 4.2.3. ROVR
Section 5.3 of [RFC8505] introduces the Registration Ownership Section 5.3 of [RFC8505] introduces the Registration Ownership
Verifier (ROVR) field of variable length from 64 to 256 bits. The Verifier (ROVR) field of variable length from 64 to 256 bits. The
ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was
used to identify uniquely an Address Registration with the Link-Layer used to identify uniquely an Address Registration with the Link-Layer
address of the owner but provided no protection against spoofing. address of the owner but provided no protection against spoofing.
"Address Protected Neighbor Discovery for Low-power and Lossy "Address Protected Neighbor Discovery for Low-power and Lossy
Networks" [AP-ND] leverages the ROVR field as a cryptographic proof Networks" [AP-ND] leverages the ROVR field as a cryptographic proof
of ownership to prevent a rogue third party from misusing the of ownership to prevent a rogue third party from misusing the
address. [AP-ND] adds a challenge/response exchange to the [RFC8505] address. [AP-ND] adds a challenge/response exchange to the [RFC8505]
Address Registration and enables Source Address Validation by a 6LR Address Registration and enables Source Address Validation by a 6LR.
that will drop packets with a spoofed address.
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 for the use of RPL. On the other hand, it adds the
DAO to build the proxied EDAR at the Root (see Section 9), which ROVR to the DAO to build the proxied EDAR at the Root (see
means that nodes that are aware of the Host route to the 6LN are made Section 6.1), which means that nodes that are aware of the Host route
aware of the associated ROVR as well. are also aware of the ROVR associated to the Target Address.
3.3. RFC 8505 Extended DAR/DAC 4.3. RFC 8505 Extended DAR/DAC
[RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to [RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to
carry the ROVR field. The EDAR/EDAC exchange takes place between the carry the ROVR field. The EDAR/EDAC exchange takes place between the
6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN 6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN
to create, refresh and delete the corresponding state in the 6LBR. to create, refresh, and delete the corresponding state in the 6LBR.
The exchange is protected by the ARQ mechanism specified in 8.2.6 of The exchange is protected by the retry mechanism (ARQ) specified in
[RFC6775], though in an LLN, a duration longer than the RETRANS_TIMER 8.2.6 of [RFC6775], though in an LLN, a duration longer than the
[RFC4861] of 1 second may be necessary to cover the Turn Around Trip RETRANS_TIMER [RFC4861] of 1 second may be necessary to cover the
delay between the 6LR and the 6LBR. Turn Around Trip delay between the 6LR and the 6LBR.
RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to
the Root that maintains the routing state in the RPL network for the the Root that maintains the routing state in the RPL network for the
lifetime indicated by the source of the DAO. This means that for lifetime indicated by the source of the DAO. This means that for
each address, there are two keep-alive messages that traverse the each address, there are two keep-alive messages that traverse the
whole network, one to the Root and one to the 6LBR. whole network, one to the Root and one to the 6LBR.
This specification avoids the periodic EDAR/EDAC exchange across the This specification avoids the periodic EDAR/EDAC exchange across the
LLN. The 6LR turns the periodic NS(EARO) from the RUL into a DAO LLN. The 6LR turns the periodic NS(EARO) from the RUL into a DAO
message to the Root on every refresh, but it only generates the EDAR message to the Root on every refresh, but it only generates the EDAR
upon the first registration, for the purpose of DAD, which must be upon the first registration, for the purpose of DAD, which must be
verified before the address is injected in RPL. Upon the DAO verified before the address is injected in RPL. Upon the DAO
message, the Root proxies the EDAR exchange to refresh the state at message, the Root proxies the EDAR exchange to refresh the state at
the 6LBR on behalf of the 6LR, as illustrated in Figure 7. the 6LBR on behalf of the 6LR, as illustrated in Figure 8.
3.3.1. RFC 7400 Capability Indication Option 4.3.1. 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.
skipping to change at page 10, line 6 skipping to change at page 11, line 6
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 6LR that can provide reachability services for a RUL in a RPL A 6LR that can provide reachability services for a RUL in a RPL
network as specified in this document SHOULD include a 6CIO in its RA network as specified in this document MUST include a 6CIO in its RA
messages and set the L, P and E flags as prescribed by [RFC8505], see messages and set the L, P and E flags as prescribed by [RFC8505].
Section 7.1 for the corresponding behavior of the RUL.
4. Updating RFC 6550 5. Requirements on the RPL-Unware Leaf
This document provides RPL routing for a RUL. This section describes
the minimal RPL-independent functionality that the RUL needs to
implement to obtain routing services for its addresses.
5.1. Support of 6LoWPAN ND
To obtain routing services from a Router that implements this
specification, a RUL needs to implement [RFC8505] and set the "R" and
"T" flags in the EARO as discussed in Section 4.2.1 and
Section 4.2.3, respectively. The RUL is expected not to request
routing services from a Router that does not originate RA messages
with a CIO that has the L, P, and E flags all set as discussed in
Section 4.3.1, unless configured to do so. It is suggested that the
RUL also implements [AP-ND] to protect the ownership of its
addresses.
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
6LRs from which it desires routing services.
Parallel Address Registrations to several 6LRs should be performed in
an rapid sequence, using the exact same EARO for the same Address.
Gaps between the Address Registrations will invalidate some of the
routes till the Address Registration finally shows on those routes.
[RFC8505] introduces error Status values in the NA(EARO) which can be
received synchronously upon an NS(EARO) or asynchronously. The RUL
MUST support both cases and MUST refrain from using the address when
the Status Value indicates a rejection.
5.2. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either
to the final destination (e.g., a RUL) or to its attachment Router
(designated as 6LR). To terminate the IP-in-IP tunnel, the RUL, as
an IPv6 Host, 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 by other means that the RUL can handle IP-in-IP properly, which
is not mandated by [RFC8504], the Root terminates the IP-in-IP tunnel
at the parent 6LR. It is thus not necessary for a RUL to support IP-
in-IP decapsulation.
5.3. Support of the HbH Header
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
of 0x23 [USEofRPLinfo] is thus skipped when not recognized.
5.4. Support of the Routing Header
A RUL is expected to process an unknown Routing Header Type as
prescribed by section 4.4 of [RFC8200]. This implies that the Source
Routing Header with a Routing Type of 3 [RFC6554] is ignored when the
Segments Left is zero, and the packet is dropped otherwise.
6. 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 10) and multicast messages for unicast addresses (see Section 9) and multicast
addresses (see Section 11) on behalf of leaves that are not aware of addresses (see Section 10) on behalf of leaves that are not aware of
RPL. The RUL addresses are exposed as external targets [RFC6550]. RPL. The RUL addresses are exposed as external targets [RFC6550].
Conforming [USEofRPLinfo], an IP-in-IP encapsulation between the 6LR Conforming to [USEofRPLinfo], an IP-in-IP encapsulation between the
and the RPL Root is used to carry the RPL artifacts and remove them 6LR and the RPL Root is used to carry the RPL artifacts and remove
when forwarding outside the RPL domain, e.g., to a RUL. them when forwarding outside the RPL domain, e.g., to a RUL.
This document also synchronizes the liveness monitoring at the Root This document also synchronizes the liveness monitoring at the Root
and the 6LBR. The same value of lifetime is used for both, and a and the 6LBR. The same value of lifetime is used for both, and a
single keep-alive message, the RPL DAO, traverses the RPL network. A single keep-alive message, the RPL DAO, traverses the RPL network. A
new behavior is introduced whereby the RPL Root proxies the EDAR new behavior is introduced whereby the RPL Root proxies the EDAR
message to the 6LBR on behalf of the 6LR (more in Section 6), for any message to the 6LBR on behalf of the 6LR (more in Section 8), for any
6LN, RUL or RAN. Leaf node that implements the 6LN functionality in [RFC8505].
Section 6.7.7 of [RFC6550] introduces RPL Target Option, which can be
used in RPL Control messages such as the DAO message to signal a
destination prefix. Section 9 adds the capabilities to transport the
ROVR field (see Section 3.2.3) and the IPv6 Address of the prefix
advertiser when the Target is a shorter prefix, signaled by a new "F"
flag. The position of the "F" flag is indicated in Section 15.
Section 6.7.6 of [RFC6550] defines the DODAG Configuration option Section 6.7.7 of [RFC6550] introduces the RPL Target Option, which
with reserved flags. This specification defines the new "Root can be used in RPL Control messages such as the DAO message to signal
Proxies EDAR/EDAC" (P) flag and encodes it in one of these reserved a destination prefix. Section 6.1 adds the capabilities to transport
flags. The "P" flag is set to indicate that the Root performs the the ROVR field (see Section 4.2.3) and the full IPv6 Address of the
proxy operation, which implies that it supports the Updated RPL prefix advertiser when the Target is a shorter prefix, signaled by a
Target Option (see Section 9). The position of the "P" flag is new "F" flag. The position of the "F" flag is indicated in
indicated in Section 14. Section 12.4.
Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in This specification defines the new "Root Proxies EDAR/EDAC" (P) flag
the DIO Base Object. The new "P" flag is defined only for MOP value and encodes it in one of these reserved flags of the the RPL DODAG
between 0 to 6. For a MOP value of 7 or above, the flag MAY be Configuration option , more in Section 6.2. The position of the "P"
redefined and MUST NOT be interpreted as "Root Proxies EDAR/EDAC" flag is indicated in Section 12.3.
unless the specification of the MOP indicates to do so.
The RPL Status defined in section 6.5.1 of [RFC6550] for use in the The RPL Status defined in section 6.5.1 of [RFC6550] for use in the
DAO-ACK message is extended to be placed in DCO messages DAO-ACK message is extended to be placed in DCO messages
[EFFICIENT-NPDAO] as well. Furthermore, this specification enables [EFFICIENT-NPDAO] as well. Furthermore, this specification enables
to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO
messages, embedded in a RPL Status, more in Section 8. messages, embedded in a RPL Status, more in Section 6.3.
5. Updating draft-ietf-roll-efficient-npdao
[EFFICIENT-NPDAO] defines the DCO for RPL Storing Mode only, with a
link-local scope. This specification extends its use to the Non-
Storing MOP, whereby the DCO is sent unicast by the Root directly to
the RAN that injected the DAO message for the considered target.
This specification leverages the DCO between the Root and the 6LR
that serves as attachment router for a RUL.
6. Updating RFC 8505
This document updates [RFC8505] to change the behavior of a RPL
Router acting as 6LR in the 6LoWPAN ND Address Registration of a RUL
acting as 6LN. If the RPL Root advertise the capability to proxy the
EDAR/EDAC exchange to the 6LBR, the 6LR refrains from sending the
keep-alive EDAR message. Instead, if it is separated from the 6LBR,
the Root regenerates the EDAR message to the 6LBR periodically, upon
a DAO message that signals the liveliness of the Address.
7. Requirements on the RPL-Unware Leaf
This document provides RPL routing for a RUL, that is a 6LN acting as 6.1. Updated RPL Target Option
an IPv6 Host and not aware of RPL. Still, a minimal RPL-independent
functionality is required from the RUL to obtain routing services.
7.1. Support of 6LoWPAN ND This specification updates the RPL Target Option to transport the
ROVR that was also defined for 6LoWPAN ND messages. This enables the
RPL Root to generate the proxied EDAR message to the 6LBR.
In order to obtain routing services from a 6LR, a RUL MUST implement The new "F" flag is set to indicate that the Target Prefix field
[RFC8505] and set the "R" and "T" flags in the EARO. The RUL SHOULD contains the address of the advertising node in full, in which case
support [AP-ND] to protect the ownership of its addresses. The RUL the length of the Target Prefix field is 16 bytes regardless of the
MUST NOT request routing services from a 6LR that does not originate value of the Prefix Length field. If the "F" flag is reset, the
RA messages with a CIO that has the L, P, and E flags all set as Target Prefix field MUST be aligned to the next byte boundary after
discussed in Section 3.3.1, unless configured to do so. the size (expressed in bits) indicated by the Prefix Length field.
Padding bits are reserved and set to 0 as prescribed by section 6.7.7
of [RFC6550].
A RUL that may attach to multiple 6LRs MUST prefer those that provide With this specification the ROVR is the remainder of the RPL Target
routing services. The RUL MUST register to all the 6LRs from which Option. The size of the ROVR is indicated in a new ROVR Size field
it desires routing services. that is encoded to map one-to-one with the Code Suffix in the EDAR
message (see table 4 of [RFC8505]).
Parallel Address Registrations to several 6LRs SHOULD be performed in The modified format is illustrated in Figure 3. It is backward
an rapid sequence, using the exact same EARO for the same Address. compatible with the Target Option in [RFC6550] and SHOULD be used as
Gaps between the Address Registrations will invalidate some of the a replacement in new implementations even for Storing Mode operations
routes till the Address Registration finally shows on those routes. in preparation for upcoming security mechanisms based in the ROVR.
[RFC8505] introduces error Status values in the NA(EARO) which can be 0 1 2 3
received synchronously upon an NS(EARO) or asynchronously. The RUL 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
MUST support both cases and MUST refrain from using the address when +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
the Status Value indicates a rejection. | Type = 0x05 | Option Length |ROVRsz |F|Flags| Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Target Prefix (Variable Length) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
... Registration Ownership Verifier (ROVR) ...
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.2. External Routes and RPL Artifacts Figure 3: Updated Target Option
Section 4.1 of [USEofRPLinfo] provides a set of rules detailed below New fields:
that MUST be followed for routing packets from and to a RUL.
A 6LR that acts as a border router for external routes advertises ROVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, or 4,
them using Non-Storing Mode DAO messages that are unicast directly to denoting a ROVR size of 64, 128, 192, or 256 bits, respectively.
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
routed via the Root. The RPL Root tunnels the packets directly to
the 6LR that advertised the external route, which decapsulates and
forwards the original (inner) packet.
The RPL Non-Storing MOP signaling and the associated IP-in-IP F: 1-bit flag. Set to indicate that Target Prefix field contains an
encapsulated packets appear as normal traffic to the intermediate Address of prefix advertiser in full.
Routers. The support of external routes only impacts the Root 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
routers. A RUL is an example of a destination that is reachable via
an external route that happens to be also a Host route.
The RPL data packets always carry a Hop-by-Hop Header to transport a Registration Ownership Verifier (ROVR): This is the same field as in
RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates the EARO, see [RFC8505]
its packets with an RPI, the 6LR needs to tunnel them to the Root to
add the RPI. As a rule of a thumb and except for the very special
case above, the packets from and to a RUL are always encapsulated
using an IP-in-IP tunnel between the Root and the 6LR that serves the
RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4,
8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details).
In Non-Storing Mode, packets going down carry a Source Routing Header 6.2. Updated DODAG Configuration Option
(SRH). The IP-in-IP encapsulation, the RPI and the SRH are
collectively called the "RPL artifacts" and can be compressed using
[RFC8138]. Figure 10 presents an example compressed format for a
packet forwarded by the Root to a RUL in a Storing Mode DODAG.
The inner packet that is forwarded to the RUL may carry some RPL The DODAG Configuration Option is defined in Section 6.7.6 of
artifacts, e.g., an RPI if the original packet was generated with it, [RFC6550]. Its purpose is extended to distribute configuration
and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the information affecting the construction and maintenance of the DODAG,
RUL to support the basic "IPv6 Node Requirements" [RFC8504]. In as well as operational parameters for RPL on the DODAG, through the
particular the RUL is expected to ignore the RPL artifacts that are DODAG. As shown in Figure 4, the Option was originally designed with
either consumed or not applicable to a Host. 4 bit positions reserved for future use as Flags.
A RUL is not expected to support the compression method defined in 0 1 2 3
[RFC8138]. Unless configured otherwise, the border router MUST 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
restore the outgoing packet before forwarding over an external route, +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
even if it is not the destination of the incoming packet, and even | Type = 0x04 |Opt Length = 14| |P| | |A| ... |
when delivering to a RUL. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
7.2.1. Support of IPv6 Encapsulation Figure 4: DODAG Configuration Option (Partial View)
Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either This specification defines a new flag "Root Proxies EDAR/EDAC" (P).
to the final destination (6LN) or to its attachment router (6LR). To The "P" flag is set to indicate support for this specification at the
terminate the IP-in-IP tunnel, the 6LN, as an IPv6 Host, must be able Root within the DODAG. The "P" flag is encoded in position 1 of the
to decapsulate the tunneled packet and either drop the inner packet reserved Flags in the DODAG Configuration Option (counting from bit 0
if it is not the final destination, or pass it to the upper layer for as the most significant bit) and set to 0 in legacy implementations
further processing. Unless it is aware by other means that the RUL as specified respectively in Sections 20.14 and 6.7.6 of [RFC6550].
can handle IP-in-IP properly, which is not mandated by [RFC8504], the
Root terminates the IP-in-IP tunnel at the parent 6LR. It is thus
not necessary for a RUL to support IP-in-IP decapsulation.
7.2.2. Support of the HbH Header The "P" flag is set to indicate that the Root performs the proxy
operation, which implies that it supports the Updated RPL Target
Option (see Section 6.1).
A RUL is expected to process an Option Type in a Hop-by-Hop Header as The RPL DODAG Configuration Option is typically placed in a DODAG
prescribed by section 4.2 of [RFC8200]. This means that the RPI with Information Object (DIO) message. The DIO message propagates down
an Option Type of 0x23 [USEofRPLinfo] must be skipped when not the DODAG to form and then maintain its structure. The DODAG
recognized. Configuration Option is copied unmodified from parents to children.
7.2.3. Support of the Routing Header Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in
the DIO Base Object. This specification applies to MOP values 0 to
6. For a MOP value of 7, the bit in position 1 is considered
unallocated and [RFC8138] MUST be used by default.
A RUL is expected to process an unknown Routing Header Type as [RFC6550] states that "Nodes other than the DODAG Root MUST NOT
prescribed by section 4.4 of [RFC8200]. This implies that the Source modify this information when propagating the DODAG Configuration
Routing Header with a Routing Type of 3 [RFC6554] is ignored when the option". Therefore, a legacy parent propagates the "P" flag as set
Segments Left is zero, and the packet is dropped otherwise. by the Root whether it supports this specification or not. So when
the "P" flag is set, it is transparently flooded to all the nodes in
the DODAG.
8. Updated RPL Status 6.3. 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
The 6LoWPAN ND Status was defined for use in the EARO and the The 6LoWPAN ND Status was defined for use in the EARO and the
currently defined values are listed in table 1 of [RFC8505]. This currently defined values are listed in table 1 of [RFC8505]. This
specification enables to carry the 6LoWPAN ND Status values in RPL specification enables to carry the 6LoWPAN ND Status values in RPL
DAO and DCO messages, embedded in the RPL Status field. DAO and DCO messages, embedded in the RPL Status field.
To achieve this, Section 13.2 reduces the range of the EARO Status To achieve this, Section 12.2 reduces the range of the EARO Status
values to 0-63 to ensure that they fit within a RPL Status as shown values to 0-63 to ensure that they fit within a RPL Status as shown
in Figure 3. in Figure 5.
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 5: RPL Status Format
The following RPL Status subfields are defined: The following RPL Status subfields are defined:
E: 1-bit flag. Set to indicate a rejection. When not set, a value E: 1-bit flag. Set to indicate a rejection. When not set, a value
of 0 indicates Success/Unqualified acceptance and other values of 0 indicates Success/Unqualified acceptance and other values
indicate "not an outright rejection" as per RFC 6550. indicate "not an outright rejection" as per RFC 6550.
A: 1-bit flag. Indicates the type of the Status Value. A: 1-bit flag. Indicates the type of the Status Value.
Status Value: 6-bit unsigned integer. If the 'A' flag is set this Status Value: 6-bit unsigned integer. If the 'A' flag is set this
skipping to change at page 14, line 38 skipping to change at page 16, line 15
When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a EDAC When building a DCO or a DAO-ACK message upon an IPv6 ND NA or a EDAC
message, the RPL Root MUST copy the 6LoWPAN ND Status unchanged in message, the RPL Root MUST copy the 6LoWPAN ND Status unchanged in
the RPL Status and set the 'A' bit. The RPL Root MUST set the 'E' the RPL Status and set the 'A' bit. The RPL Root MUST set the 'E'
flag for Values in range 1-10 which are all considered rejections. flag for Values in range 1-10 which are all considered rejections.
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' bit set, the 6LR MUST copy the RPL a RPL Status that has the 'A' bit 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.
9. Updated RPL Target Option 7. Updating draft-ietf-roll-efficient-npdao
This specification updates the RPL Target Option to transport the
ROVR that was also defined for 6LoWPAN ND messages. This enables the
RPL Root to generate the proxied EDAR message to the 6LBR.
The new "F" flag is set to indicate that the Target Prefix field
contains the address of the advertising node in full, in which case
the length of the Target Prefix field is 16 bytes regardless of the
value of the Prefix Length field.
If the "F" flag is reset, the Target Prefix field MUST be aligned to
the next byte boundary after the size (expressed in bits) indicated
by the Prefix Length field. Padding bits are reserved and set to 0
as prescribed by section 6.7.7 of [RFC6550].
With this specification the ROVR is the remainder of the RPL Target
Option. The size of the ROVR is indicated in a new ROVR Size field
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 in new implementations even for Storing Mode operations
in preparation for upcoming security mechanisms based in the ROVR.
0 1 2 3
0 1 2 3 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 |F|Flags| Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Target Prefix (Variable Length) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
... Registration Ownership Verifier (ROVR) ...
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Updated Target Option
New fields: [EFFICIENT-NPDAO] defines the DCO for RPL Storing Mode only, with a
link-local scope. This specification extends its use to the Non-
Storing MOP, whereby the DCO is sent unicast by the Root directly to
the RAN that injected the DAO message for the considered target.
ROVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, or 4, This specification leverages the DCO between the Root and the 6LR
denoting a ROVR size of 64, 128, 192, or 256 bits, respectively. that serves as attachment Router for a RUL.
F: 1-bit flag. Set to indicate that Target Prefix field contains an 8. Updating RFC 8505
Address of prefix advertiser in full.
Registration Ownership Verifier (ROVR): This is the same field as in This document updates [RFC8505] to change the behavior of a RPL
the EARO, see [RFC8505] Router acting as 6LR and of a RUL acting as 6LN in the 6LoWPAN ND
Address Registration. If the RPL Root advertise the capability to
proxy the EDAR/EDAC exchange to the 6LBR, the 6LR refrains from
sending the keep-alive EDAR message. Instead, if it is separated
from the 6LBR, the Root regenerates the EDAR message to the 6LBR
periodically, upon a DAO message that signals the liveliness of the
Address.
10. 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.
If the "P" flag is reset, the 6LR MUST generate the periodic EDAR If the "P" flag is reset, the 6LR MUST generate the periodic EDAR
messages and process the returned status as specified in [RFC8505]. messages and process the returned status as specified in [RFC8505].
If the EDAC indicates success, the rest of the flow takes place as If the EDAC indicates success, the rest of the flow takes place as
presented but without the proxied EDAR/EDAC exchange. presented but without the proxied EDAR/EDAC exchange.
10.1. General Flow 9.1. General Flow
This specification eliminates the need to exchange keep-alive This specification eliminates the need to exchange keep-alive
Extended Duplicate Address messages, EDAR and EDAC, all the way from Extended Duplicate Address messages, EDAR and EDAC, all the way from
a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange
with the 6LBR is proxied by the RPL Root upon the DAO message that with the 6LBR is proxied by the RPL Root upon the DAO message that
refreshes the RPL routing state. The first EDAR upon a new refreshes the RPL routing state. The first EDAR upon a new
Registration cannot be proxied, though, as it serves for the purpose Registration cannot be proxied, though, as it serves for the purpose
of DAD, which must be verified before the address is injected in RPL. of DAD, which must be verified before the address is injected in RPL.
In a RPL network where the function is enabled, refreshing the state In a RPL network where the function is enabled, refreshing the state
in the 6LBR is the responsibility of the Root. Consequently, only in the 6LBR is the responsibility of the Root. Consequently, only
addresses that are injected in RPL will be kept alive at the 6LBR by addresses that are injected in RPL will be kept alive at the 6LBR by
the RPL Root. the RPL Root.
Since RULs are advertised using Non-Storing Mode, the DAO message Since RULs are advertised using Non-Storing Mode, the DAO message
flow and the keep alive EDAR/EDAC can be nested within the Address flow and the keep alive EDAR/EDAC can be nested within the Address
(re)Registration flow. Figure 5 illustrates that for the first (re)Registration flow. Figure 6 illustrates that for the first
Registration, both the DAD and the keep-alive EDAR/EDAC exchanges Registration, both the DAD and the keep-alive EDAR/EDAC exchanges
happen in the same sequence. happen in the same sequence.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | Extended DAR | | | Extended DAR |
| |--------------------------------->| | |--------------------------------->|
| | | | | |
skipping to change at page 16, line 47 skipping to change at page 17, line 47
| | | EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
Figure 5: First RUL Registration Flow Figure 6: First RUL Registration Flow
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.
On the first Address Registration, illustrated in Figure 5 for RPL On the first Address Registration, illustrated in Figure 6 for RPL
Non-Storing Mode, the Extended Duplicate Address exchange takes place Non-Storing Mode, the Extended Duplicate Address exchange takes place
as prescribed by [RFC8505]. If the exchange fails, the 6LR returns as prescribed by [RFC8505]. If the exchange fails, the 6LR returns
an NA message with a negative status to the 6LN, the NCE is not an NA message with a negative status to the 6LN, the NCE is not
created and the address is not injected in RPL. If it is successful, created and the address is not injected in RPL. If it is successful,
the 6LR creates an NCE and injects the Registered Address in the RPL the 6LR creates an NCE and injects the Registered Address in the RPL
routing using a DAO/DAO-ACK exchange with the RPL DODAG Root. routing using a DAO/DAO-ACK exchange with the RPL DODAG Root.
An issue may be detected later, e.g., the address moves within the An issue may be detected later, e.g., the address moves within the
LLN or to a different Root on a backbone [6BBR]. In that case the LLN or to a different Root on a backbone [6BBR]. In that case the
value of the status that indicates the issue can be passed from value of the status that indicates the issue can be passed from
6LoWPAN ND to RPL and back as illustrated in Figure 6. 6LoWPAN ND to RPL and back as illustrated in Figure 7.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| | | NA(EARO, Status) | | | | NA(EARO, Status) |
| | |<-----------------| | | |<-----------------|
| | DCO(Status) | | | | DCO(Status) | |
| |<------------| | | |<------------| |
| NA(EARO, Status) | | | | NA(EARO, Status) | | |
|<-----------------| | | |<-----------------| | |
| | | | | | | |
Figure 6: Asynchronous Issue Figure 7: 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 the refresh of an NCE in the 6LR alive before lifetime expires. Upon the refresh of an
Address re-Registration, as illustrated in Figure 7, the 6LR injects Address re-Registration, as illustrated in Figure 8, the 6LR injects
the Registered Address in RPL. the Registered Address in RPL.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 7: Next RUL Registration Flow Figure 8: Next RUL Registration Flow
This is what causes the RPL Root to refresh the state in the 6LBR, This is what causes the RPL Root to refresh the state in the 6LBR,
using an EDAC message. In case of an error in the proxied EDAR flow, using an EDAC message. In case of an error in the proxied EDAR flow,
the error is returned in the DAO-ACK using a RPL Status with the 'A' the error is returned in the DAO-ACK using a RPL Status with the 'A'
flag set that imbeds a 6LoWPAN Status Value as discussed in flag set that imbeds a 6LoWPAN Status Value as discussed in
Section 8. Section 6.3.
The 6LR may receive a requested DAO-ACK after it received an The 6LR may receive a requested DAO-ACK after it received an
asynchronous DCO, but the negative Status in the DCO supersedes a asynchronous DCO, but the negative Status in the DCO supersedes a
positive Status in the DAO-ACK regardless of the order in which they positive Status in the DAO-ACK regardless of the order in which they
are received. Upon the DAO-ACK - or the DCO if one arrives first - are received. Upon the DAO-ACK - or the DCO if one arrives first -
the 6LR responds to the RUL with an NA(EARO). the 6LR responds to the RUL with an NA(EARO).
The RUL MAY terminate the registration at any time by using a The RUL MAY terminate the registration at any time by using a
Registration Lifetime of 0. This specification requires that the RPL Registration Lifetime of 0. This specification requires that the RPL
Target Option transports the ROVR. This way, the same flow as the Target Option transports the ROVR. This way, the same flow as the
heartbeat flow is sufficient to inform the 6LBR using the Root as heartbeat flow is sufficient to inform the 6LBR using the Root as
proxy as illustrated in Figure 7. proxy as illustrated in Figure 8.
Any combination of the logical functions of 6LR, Root and 6LBR might Any combination of the logical functions of 6LR, Root and 6LBR might
be collapsed in a single node. be collapsed in a single node.
10.2. Detailed Operation 9.2. Detailed Operation
10.2.1. Perspective of the RUL Acting as 6LN 9.2.1. Perspective of the RUL Acting as 6LN
This specification does not alter the operation of a 6LoWPAN ND- This specification does not alter the operation of a 6LoWPAN ND-
compliant 6LN, and a RUL is expected to operate as follows: compliant 6LN, and a RUL is expected to operate as follows:
1. The 6LN obtains an IPv6 global address, either using Stateless 1. The 6LN obtains an IPv6 global address, either using Stateless
Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix
Information Option (PIO) [RFC4861] found in an RA message, or Information Option (PIO) [RFC4861] found in an RA message, or
some other means such as DHCPv6 [RFC3315]. some other means such as DHCPv6 [RFC3315].
2. Once it has formed an address, the 6LN (re)registers its address 2. Once it has formed an address, the 6LN (re)registers its address
skipping to change at page 19, line 36 skipping to change at page 20, line 36
"I" field to zero to signal "topological information to be passed to "I" field to zero to signal "topological information to be passed to
a routing process" as specified in section 5.1 of [RFC8505]. a routing process" as specified in section 5.1 of [RFC8505].
A RUL is not expected to produce RPL artifacts in the data packets, A RUL is not expected to produce RPL artifacts in the data packets,
but it MAY do so. For instance, if the RUL has a minimal awareness but it MAY do so. For instance, if the RUL has a minimal awareness
of the RPL Instance then it can build an RPI. A RUL that places an of the RPL Instance then it can build an RPI. A RUL that places an
RPI in a data packet MUST indicate the RPLInstanceID of the RPL RPI in a data packet MUST indicate the RPLInstanceID of the RPL
Instance where the packet should be forwarded. All the flags and the Instance where the packet should be forwarded. All the flags and the
Rank field are set to zero as specified by section 11.2 of [RFC6550]. Rank field are set to zero as specified by section 11.2 of [RFC6550].
10.2.2. Perspective of the Border Router Acting as 6LR 9.2.2. Perspective of the Border Router Acting as 6LR
Also as prescribed by [RFC8505], the 6LR generates an EDAR message Also as prescribed by [RFC8505], the 6LR generates an EDAR message
upon reception of a valid NS(EARO) message for the registration of a upon reception of a valid NS(EARO) message for the registration of a
new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange
succeeds, then the 6LR installs an NCE for the Registration Lifetime. succeeds, then the 6LR installs an NCE for the Registration Lifetime.
For the registration refreshes, if the RPL Root has indicated that it For the registration refreshes, if the RPL Root has indicated that it
proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see
Section 4), the 6LR MUST refrain from sending the keep-alive EDAR. Section 6), the 6LR MUST refrain from sending the keep-alive EDAR.
If the "R" flag is set in the NS(EARO), the 6LR MUST inject the Host If the "R" flag is set in the NS(EARO), the 6LR MUST inject the Host
route in RPL, unless this is barred for other reasons, such as the route in RPL, unless this is barred for other reasons, such as the
saturation of the RPL parents. The 6LR MUST use a RPL Non-Storing saturation of the RPL parents. The 6LR MUST use a RPL Non-Storing
Mode signaling and the updated Target Option (see Section 9). The Mode signaling and the updated Target Option (see Section 6.1). The
6LR MUST request a DAO-ACK by setting the 'K' flag in the DAO 6LR MUST request a DAO-ACK by setting the 'K' flag in the DAO
message. Success injecting the route to the RUL is indicated by the message. Success injecting the route to the RUL is indicated by the
'E' flag set to 0 in the RPL status of the DAO-ACK message. 'E' flag set to 0 in the RPL status of the DAO-ACK message.
The Opaque field in the EARO hints the 6LR on the RPL Instance that The Opaque field in the EARO hints the 6LR on the RPL Instance that
SHOULD be used for the DAO advertisements, and for the forwarding of SHOULD be used for the DAO advertisements, and for the forwarding of
packets sourced at the registered address when there is no RPI in the packets sourced at the registered address when there is no RPI in the
packet, in which case the 6LR MUST encapsulate the packet to the Root packet, in which case the 6LR MUST encapsulate the packet to the Root
adding an RPI in the outer header. If the Opaque field is zero, the adding an RPI in the outer header. If the Opaque field is zero, the
6LR is free to use the default RPL Instance (zero) for the registered 6LR is free to use the default RPL Instance (zero) for the registered
skipping to change at page 20, line 27 skipping to change at page 21, line 27
then the 6LR MUST consider that the Opaque field is zero; else, that then the 6LR MUST consider that the Opaque field is zero; else, that
is if the 6LR participates to the suggested RPL Instance, then the is if the 6LR participates to the suggested RPL Instance, then the
6LR SHOULD use that Instance for the Registered Address. 6LR SHOULD use that Instance for the Registered Address.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is signaled as Target Prefix in the 1. The Registered Address is signaled as 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. The ROVR field is copied unchanged from the EARO set to 128. The ROVR field is copied unchanged from the EARO
(see Section 9). (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 RPL Transit Information
Option (TIO) associated with the Target Option Option (TIO) associated with the 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
redistributes an external target into the RPL network redistributes an external target into the RPL network
4. the Path Lifetime in the TIO is computed from the Lifetime in the 4. the Path Lifetime in the TIO is computed from the Lifetime in the
EARO Option. This adapts it to the Lifetime Units used in the EARO Option. This adapts it to the Lifetime Units used in the
skipping to change at page 21, line 32 skipping to change at page 22, line 32
enabled, in case of a DAO-ACK or a DCO indicating transporting an enabled, in case of a DAO-ACK or a DCO indicating transporting an
EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge
the 6LN for ownership of the address, as described in section 6.1 of the 6LN for ownership of the address, as described in section 6.1 of
[AP-ND], before the Registration is complete. This ensures that the [AP-ND], before the Registration is complete. This ensures that the
address is validated before it is injected in the RPL routing. address is validated before it is injected in the RPL routing.
If the challenge succeeds then the operations continue as normal. In If the challenge succeeds then the operations continue as normal. In
particular a DAO message is generated upon the NS(EARO) that proves particular a DAO message is generated upon the NS(EARO) that proves
the ownership of the address. If the challenge failed, the 6LR the ownership of the address. If the challenge failed, the 6LR
rejects the registration as prescribed by AP-ND and may take actions rejects the registration as prescribed by AP-ND and may take actions
to protect itself against DoS attacks by a rogue 6LN, see Section 12. to protect itself against DoS attacks by a rogue 6LN, see Section 11.
The 6LR may at any time send a unicast asynchronous NA(EARO) with the The 6LR may at any time send a unicast asynchronous NA(EARO) with the
"R" flag reset to signal that it stops providing routing services, "R" flag reset to signal that it stops providing routing services,
and/or with the EARO Status 2 "Neighbor Cache full" to signal that it and/or with the EARO Status 2 "Neighbor Cache full" to signal that it
removes the NCE. It may also send a final RA, unicast or multicast, removes the NCE. It may also send a final RA, unicast or multicast,
with a Router Lifetime field of zero, to signal that it stops serving with a Router Lifetime field of zero, to signal that it stops serving
as router, as specified in section 6.2.5 of [RFC4861]. as Router, as specified in section 6.2.5 of [RFC4861].
If a 6LR receives a valid NS(EARO) message with the "R" flag reset If a 6LR receives a valid NS(EARO) message with the "R" flag reset
and a Registration Lifetime that is not 0, and the 6LR was injecting and a Registration Lifetime that is not 0, and the 6LR was injecting
the Registered Address due to previous NS(EARO) messages with the "R" the Registered Address due to previous NS(EARO) messages with the "R"
flag set, then the 6LR MUST stop injecting the address. It is up to flag set, then the 6LR MUST stop injecting the address. It is up to
the Registering 6LN to maintain the corresponding route from then on, the Registering 6LN to maintain the corresponding route from then on,
either keeping it active via a different 6LR or by acting as a RAN either keeping it active via a different 6LR or by acting as a RAN
and managing its own reachability. and managing its own reachability.
10.2.3. Perspective of the RPL Root 9.2.3. Perspective of the RPL Root
A RPL Root SHOULD set the "P" flag in the RPL DODAG Configuration A RPL Root SHOULD set the "P" flag in the RPL DODAG Configuration
Option of the DIO messages that it generates (see Section 4) to Option of the DIO messages that it generates (see Section 6) to
signal that it proxies the EDAR/EDAC exchange and supports the signal that it proxies the EDAR/EDAC exchange and supports the
Updated RPL Target option. The remainder of this section assumes Updated RPL Target option. The remainder of this section assumes
that it does. that it does.
Upon reception of a DAO message, for each updated RPL Target Option Upon reception of a DAO message, for each updated RPL Target Option
(see Section 9) that creates or updates an existing RPL state, the (see Section 6.1) that creates or updates an existing RPL state, the
Root MUST notify the 6LBR. This can be done using an internal API if Root MUST notify the 6LBR. This can be done using an internal API if
they are integrated, or using a proxied EDAR/EDAC exchange if they they are integrated, or using a proxied EDAR/EDAC exchange if they
are separate entities. are separate entities.
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
skipping to change at page 22, line 43 skipping to change at page 23, line 43
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. Else, if the then the Root MUST send a DAO-ACK back to the 6LR. Else, if the
Status in the EDAC message is not "Success", then it MUST send an Status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. asynchronous DCO to the 6LR.
In either case, the EDAC Status is embedded in the RPL Status with In either case, the EDAC Status is embedded in the RPL Status with
the 'A' flag set. the 'A' flag set.
10.2.4. Perspective of the 6LBR 9.2.4. Perspective of the 6LBR
The 6LBR is unaware that the RPL Root is not the new attachment 6LR The 6LBR is unaware that the RPL Root is not the new attachment 6LR
of the RUL, so it is not impacted by this specification. of the RUL, so it is not impacted by this specification.
Upon reception of an EDAR message, the 6LBR acts as prescribed by Upon reception of an EDAR message, the 6LBR acts as prescribed by
[RFC8505] and returns an EDAC message to the sender. [RFC8505] and returns an EDAC message to the sender.
11. 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 of the interested children. This remains true when unicast to each of the interested children. This remains true when
forwarding between the 6LR and the listener 6LN. forwarding between the 6LR and the listener 6LN.
"Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its "Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its
updated version "Multicast Listener Discovery Version 2 (MLDv2) for updated version "Multicast Listener Discovery Version 2 (MLDv2) for
IPv6" [RFC3810] provide an interface for a listener to register to IPv6" [RFC3810] provide an interface for a listener to register to
multicast flows. MLDv2 is backwards compatible with MLD, and adds in multicast flows. MLDv2 is backwards compatible with MLD, and adds in
particular the capability to filter the sources via black lists and particular the capability to filter the sources via black lists and
white lists. In the MLD model, the Router is a "querier" and the white lists. In the MLD model, the Router is a "querier" and the
Host is a multicast listener that registers to the querier to obtain Host is a multicast listener that registers to the querier to obtain
copies of the particular flows it is interested in. copies of the particular flows it is interested in.
On the first Address Registration, as illustrated in Figure 8, the On the first Address Registration, as illustrated in Figure 9, the
6LN, as an MLD listener, sends an unsolicited Report to the 6LR in 6LN, as an MLD listener, sends an unsolicited Report to the 6LR in
order to start receiving the flow immediately. order to start receiving the flow immediately.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| unsolicited Report | | | | unsolicited Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | | | <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | <if not listening> | | | | <if not listening> |
| | | unsolicited Report | | | | unsolicited Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
Figure 8: First Multicast Registration Flow Figure 9: First Multicast Registration Flow
Since multicast Layer-2 messages are avoided, it is important that Since multicast Layer-2 messages are avoided, it is important that
the asynchronous messages for unsolicited Report and Done are sent the asynchronous messages for unsolicited Report and Done are sent
reliably, for instance using a Layer-2 acknowledgment, or attempted reliably, for instance using a Layer-2 acknowledgment, or attempted
multiple times. multiple times.
The 6LR acts as a generic MLD querier and generates a DAO for the The 6LR acts as a generic MLD querier and generates a DAO for the
multicast target. The lifetime of the DAO is set to be in the order multicast target. The lifetime of the DAO is set to be in the order
of the Query Interval, yet larger to account for variable propagation of the Query Interval, yet larger to account for variable propagation
delays. delays.
skipping to change at page 24, line 19 skipping to change at page 25, line 19
Upon a DAO with a multicast target, the RPL Root checks if it is 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 already registered as a listener for that address, and if not, it
performs its own unsolicited Report for the multicast target. performs its own unsolicited Report for the multicast target.
An Address re-Registration is pulled periodically by 6LR acting as An Address re-Registration is pulled periodically by 6LR acting as
querier. Note that the message may be sent unicast to all the known querier. Note that the message may be sent unicast to all the known
individual listeners. individual listeners.
Upon the timing out of the Query Interval, the 6LR sends a Query to Upon the timing out of the Query Interval, the 6LR sends a Query to
each of its listeners, and gets a Report back that is mapped into a each of its listeners, and gets a Report back that is mapped into a
DAO, as illustrated in Figure 9: DAO, as illustrated in Figure 10:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | | | <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | | | | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 9: Next Registration Flow Figure 10: 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.
12. Security Considerations 11. Security Considerations
First of all, it is worth noting that with [RFC6550], every node in First of all, it is worth noting that with [RFC6550], every node in
the LLN is RPL-aware and can inject any RPL-based attack in the the LLN is RPL-aware and can inject any RPL-based attack in the
network. This specification isolates edge nodes that can only network. This specification isolates edge nodes that can only
interact with the RPL routers using 6LoWPAN ND, meaning that they interact with the RPL Routers using 6LoWPAN ND, meaning that they
cannot perform RPL insider attacks. cannot perform RPL insider attacks.
6LoWPAN ND can optionally provide SAVI features with [AP-ND], which 6LoWPAN ND can optionally provide SAVI features with [AP-ND], which
reduces even more the attack perimeter that is available to the edge reduces even more the attack perimeter that is available to the edge
nodes. nodes.
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), Denial-Of-Service attacks
an impersonated 6LBR would destroy state in the network by using the whereby a rogue 6LR creates a high churn in the RPL network by
"Removed" Status code. advertising and removing many forged addresses, or bombing attack
whereby an impersonated 6LBR would destroy state in the network by
using the "Removed" Status code.
This trust model could be at a minimum based on a Layer-2 Secure This trust model could be at a minimum based on a Layer-2 Secure
joining and the Link-Layer security. This is a generic 6LoWPAN joining and the Link-Layer security. This is a generic 6LoWPAN
requirement, see Req5.1 in Appendix of [RFC8505]. requirement, see Req5.1 in Appendix of [RFC8505]. It is needed in
particular to prevent Denial-Of-Service attacks whereby a rogue 6LN
creates a high churn in the RPL network by constantly registering and
deregistering addresses with the "R" flag set in the EARO.
Additionally, the trust model could include a role validation to Additionally, the trust model could include a role validation to
ensure that the node that claims to be a 6LBR or a RPL Root is ensure that the node that claims to be a 6LBR or a RPL Root is
entitled to do so. entitled to do so.
At the time of this writing RPL does not have a zerotrust model At the time of this writing RPL does not have a zerotrust model
whereby it is possible to validate the origin of an address that is whereby it is possible to validate the origin of an address that is
injected in a DAO. This specification makes a first step in that injected in a DAO. This specification makes a first step in that
direction by allowing the Root to challenge the RUL via the 6LR that direction by allowing the Root to challenge the RUL via the 6LR that
serves it. serves it.
13. IANA Considerations 12. IANA Considerations
13.1. Fixing the Address Registration Option Flags 12.1. Fixing the Address Registration Option Flags
Section 9.1 of [RFC8505] creates a Registry for the 8-bit Address Section 9.1 of [RFC8505] creates a Registry for the 8-bit Address
Registration Option Flags field. Registration Option Flags field.
IANA is requested to rename the first column of the table from "ARO IANA is requested to rename the first column of the table from "ARO
Status" to "Bit number". Status" to "Bit number".
13.2. Resizing the ARO Status values 12.2. Resizing the ARO Status values
Section 12 of [RFC6775] creates the Address Registration Option Section 12 of [RFC6775] creates the Address Registration Option
Status Values Registry with a range 0-255. Status Values Registry with a range 0-255.
This specification reduces that range to 0-63. This specification reduces that range to 0-63.
IANA is requested to reduce the upper bound of the unassigned values IANA is requested to reduce the upper bound of the unassigned values
in the Address Registration Option Status Values Registry from -255 in the Address Registration Option Status Values Registry from -255
to -63. to -63.
14. New DODAG Configuration Option Flag 12.3. 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
15. New RPL Target Option Flag 12.4. New RPL Target Option Flag
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. IANA is requested to reduce the size of Target Option Flags" field. IANA is requested to reduce the size of
the field in the Registry to 4 bits. This specification also defines the field in the Registry to 4 bits. This specification also defines
a new entry in the Registry as follows: a new entry in the Registry as follows:
+------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+============+================================+===========+ +------------+--------------------------------+-----------+
| 1 | Advertiser Address in Full (F) | THIS RFC | | 1 | Advertiser Address in Full (F) | THIS RFC |
+------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
Table 3: New RPL Target Option Flag Table 3: New RPL Target Option Flag
16. New Subregistry for the RPL Non-Rejection Status values 12.5. New Subregistry for the RPL Non-Rejection Status values
This specification creates a new Subregistry for the RPL Non- This specification creates a new Subregistry for the RPL Non-
Rejection Status values for use in RPL DAO-ACK and DCO messages with Rejection Status values for use in RPL DAO-ACK and DCO messages with
the 'A' flag reset, under the ICMPv6 parameters registry. the 'A' flag reset, under the ICMPv6 parameters registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 4: * Initial allocation is as indicated in Table 4:
+-------+------------------------+-----------+ +-------+------------------------+-----------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+========================+===========+ +-------+------------------------+-----------+
| 0 | Unqualified acceptance | RFC 6550 | | 0 | Unqualified acceptance | RFC 6550 |
+-------+------------------------+-----------+ +-------+------------------------+-----------+
Table 4: Acceptance values of the RPL Status Table 4: Acceptance values of the RPL Status
17. New Subregistry for the RPL Rejection Status values 12.6. New Subregistry for the RPL Rejection Status values
This specification creates a new Subregistry for the RPL Rejection This specification creates a new Subregistry for the RPL Rejection
Status values for use in RPL DAO-ACK and RCO messages with the 'A' Status values for use in RPL DAO-ACK and RCO messages with the 'A'
flag reset, under the ICMPv6 parameters registry. flag reset, under the ICMPv6 parameters registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 5: * Initial allocation is as indicated in Table 5:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+=======================+===============+ +-------+-----------------------+---------------+
| 0 | Unqualified rejection | This document | | 0 | Unqualified rejection | This document |
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
Table 5: Rejection values of the RPL Status Table 5: Rejection values of the RPL Status
18. 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 for their reviews and contributions to this especially Rahul Jadhav and Alvaro Retana for their reviews and
document. contributions to this document.
19. 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>.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, Listener Discovery (MLD) for IPv6", RFC 2710,
DOI 10.17487/RFC2710, October 1999, DOI 10.17487/RFC2710, October 1999,
<https://www.rfc-editor.org/info/rfc2710>. <https://www.rfc-editor.org/info/rfc2710>.
skipping to change at page 29, line 40 skipping to change at page 31, line 5
[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-23, 30 April 2020, ietf-6lo-ap-nd-23, 30 April 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-23>. <https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-23>.
[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-38, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-40,
23 March 2020, <https://tools.ietf.org/html/draft-ietf- 25 June 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-38>. roll-useofrplinfo-40>.
[EFFICIENT-NPDAO] [EFFICIENT-NPDAO]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", Work in Progress, Internet-Draft, Route Invalidation", Work in Progress, Internet-Draft,
draft-ietf-roll-efficient-npdao-18, 15 April 2020, draft-ietf-roll-efficient-npdao-18, 15 April 2020,
<https://tools.ietf.org/html/draft-ietf-roll-efficient- <https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-18>. npdao-18>.
20. Informative References 15. Informative References
[RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem
Statement and Requirements for IPv6 over Low-Power Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing", Wireless Personal Area Network (6LoWPAN) Routing",
RFC 6606, DOI 10.17487/RFC6606, May 2012, RFC 6606, DOI 10.17487/RFC6606, May 2012,
<https://www.rfc-editor.org/info/rfc6606>. <https://www.rfc-editor.org/info/rfc6606>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
skipping to change at page 31, line 7 skipping to change at page 32, line 17
January 2019, <https://www.rfc-editor.org/info/rfc8504>. January 2019, <https://www.rfc-editor.org/info/rfc8504>.
[6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 [6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", Work in Progress, Internet-Draft, draft- Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-20, 23 March 2020, ietf-6lo-backbone-router-20, 23 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-backbone- <https://tools.ietf.org/html/draft-ietf-6lo-backbone-
router-20>. router-20>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 10 illustrates the case in Storing Mode where the packet is Figure 11 illustrates the case in Storing Mode where the packet is
received from the Internet, then the Root encapsulates the packet to received from the Internet, then the Root encapsulates the packet to
insert the RPI and deliver to the 6LR that is the parent and last hop insert the RPI and deliver to the 6LR that is the parent and last hop
to the final destination, which is not known to support [RFC8138]. to the final destination, which is not known to support [RFC8138].
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4 bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
<- No RPL artifact ... <- No RPL artifact ...
Figure 10: Encapsulation to Parent 6LR in Storing Mode Figure 11: Encapsulation to Parent 6LR in Storing Mode
The difference with the example presented in Figure 19 of [RFC8138] The difference with the example presented in Figure 19 of [RFC8138]
is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
compressed address of the 6LR as the destination address of the outer compressed address of the 6LR as the destination address of the outer
IPv6 header. In the original example the destination IP of the outer IPv6 header. In the original example the destination IP of the outer
header was elided and was implicitly the same address as the header was elided and was implicitly the same address as the
destination of the inner header. Type 1 was arbitrarily chosen, and destination of the inner header. Type 1 was arbitrarily chosen, and
the size of 0 denotes a single address in the SRH. the size of 0 denotes a single address in the SRH.
In Figure 10, the source of the IP-in-IP encapsulation is the Root, In Figure 11, the source of the IP-in-IP encapsulation is the Root,
so it is elided in the IP-in-IP 6LoRH. The destination is the parent so it is elided in the IP-in-IP 6LoRH. The destination is the parent
6LR of the destination of the inner packet so it cannot be elided. 6LR of the destination of the inner packet so it cannot be elided.
If the DODAG is operated in Storing Mode, it is the single entry in If the DODAG is operated in Storing Mode, it is the single entry in
the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH
is the first 6LoRH in the chain. In this particular example, the 6LR is the first 6LoRH in the chain. In this particular example, the 6LR
address can be compressed to 2 bytes so a Type of 1 is used. It address can be compressed to 2 bytes so a Type of 1 is used. It
results that the total length of the SRH-6LoRH is 4 bytes. results that the total length of the SRH-6LoRH is 4 bytes.
In Non-Storing Mode, the encapsulation from the Root would be similar In Non-Storing Mode, the encapsulation from the Root would be similar
to that represented in Figure 10 with possibly more hops in the SRH- to that represented in Figure 11 with possibly more hops in the SRH-
6LoRH and possibly multiple SRH-6LoRHs if the various addresses in 6LoRH and possibly multiple SRH-6LoRHs if the various addresses in
the routing header are not compressed to the same format. Note that the routing header are not compressed to the same format. Note that
on the last hop to the parent 6LR, the RH3 is consumed and removed on the last hop to the parent 6LR, the RH3 is consumed and removed
from the compressed form, so the use of Non-Storing Mode vs. Storing from the compressed form, so the use of Non-Storing Mode vs. Storing
Mode is indistinguishable from the packet format. Mode is indistinguishable from the packet format.
The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH. The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH.
When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that
precede it are also removed. The Paging Dispatch [RFC8025] may also precede it are also removed. The Paging Dispatch [RFC8025] may also
be removed if there was no previous Page change to a Page other than be removed if there was no previous Page change to a Page other than
 End of changes. 136 change blocks. 
420 lines changed or deleted 457 lines changed or added

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