draft-ietf-roll-unaware-leaves-30.txt   rfc9010.txt 
ROLL P. Thubert, Ed. Internet Engineering Task Force (IETF) P. Thubert, Ed.
Internet-Draft Cisco Systems Request for Comments: 9010 Cisco Systems
Updates: 6550, 6775, 8505 (if approved) M. Richardson Updates: 6550, 6775, 8505 M. Richardson
Intended status: Standards Track Sandelman Category: Standards Track Sandelman
Expires: 26 July 2021 22 January 2021 ISSN: 2070-1721 April 2021
Routing for RPL Leaves Routing for RPL (Routing Protocol for Low-Power
draft-ietf-roll-unaware-leaves-30 and Lossy Networks) Leaves
Abstract Abstract
This specification updates RFC6550, RFC6775, and RFC8505. It This specification provides a mechanism for a host that implements a
provides a mechanism for a host that implements a routing-agnostic routing-agnostic interface based on IPv6 over Low-Power Wireless
interface based on 6LoWPAN Neighbor Discovery to obtain reachability Personal Area Network (6LoWPAN) Neighbor Discovery to obtain
services across a network that leverages RFC6550 for its routing reachability services across a network that leverages RFC 6550 for
operations. its routing operations. It updates RFCs 6550, 6775, and 8505.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 26 July 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9010.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 6 2.1. Requirements Language
2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2. Glossary
2.3. References . . . . . . . . . . . . . . . . . . . . . . . 7 2.3. Related Documents
3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 8 3. RPL External Routes and Data-Plane Artifacts
4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 9 4. 6LoWPAN Neighbor Discovery
4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 9 4.1. Address Registration per RFC 6775
4.2. RFC 8505 Extended Address Registration . . . . . . . . . 10 4.2. Extended Address Registration per RFC 8505
4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 10 4.2.1. R Flag
4.2.2. TID, "I" Field and Opaque Fields . . . . . . . . . . 11 4.2.2. TID, "I" Field, and Opaque Field
4.2.3. Route Ownership Verifier . . . . . . . . . . . . . . 11 4.2.3. Route Ownership Verifier
4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 11 4.3. EDAR/EDAC per RFC 8505
4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 12 4.3.1. Capability Indication Option per RFC 7400
5. Requirements on the RPL-Unware leaf . . . . . . . . . . . . . 13 5. Requirements for the RPL-Unaware Leaf
5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 13 5.1. Support of 6LoWPAN ND
5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 14 5.2. Support of IPv6 Encapsulation
5.3. Support of the Hop-by-Hop Header . . . . . . . . . . . . 14 5.3. Support of the Hop-by-Hop Header
5.4. Support of the Routing Header . . . . . . . . . . . . . . 14 5.4. Support of the Routing Header
6. Enhancements to RFC 6550 . . . . . . . . . . . . . . . . . . 14 6. Enhancements to RFC 6550
6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 15 6.1. Updated RPL Target Option
6.2. Additional Flag in the RPL DODAG Configuration Option . . 17 6.2. Additional Flag in the RPL DODAG Configuration Option
6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 18 6.3. Updated RPL Status
7. Enhancements to draft-ietf-roll-efficient-npdao . . . . . . . 20 7. Enhancements to RFC 9009
8. Enhancements to RFC6775 and RFC8505 . . . . . . . . . . . . . 20 8. Enhancements to RFCs 6775 and 8505
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 20 9. Protocol Operations for Unicast Addresses
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 21 9.1. General Flow
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 24 9.2. Detailed Operation
9.2.1. Perspective of the 6LN Acting as RUL . . . . . . . . 24 9.2.1. Perspective of the 6LN Acting as a RUL
9.2.2. Perspective of the 6LR Acting as Border router . . . 25 9.2.2. Perspective of the 6LR Acting as a Border Router
9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 30 9.2.3. Perspective of the RPL DODAG Root
9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 31 9.2.4. Perspective of the 6LBR
10. Protocol Operations for Multicast Addresses . . . . . . . . . 31 10. Protocol Operations for Multicast Addresses
11. Security Considerations . . . . . . . . . . . . . . . . . . . 34 11. Security Considerations
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 12. IANA Considerations
12.1. Fixing the Address Registration Option Flags . . . . . . 35 12.1. Fixing the Address Registration Option Flags
12.2. Resizing the ARO Status values . . . . . . . . . . . . . 36 12.2. Resizing the ARO Status Values
12.3. New RPL DODAG Configuration Option Flag . . . . . . . . 36 12.3. New RPL DODAG Configuration Option Flag
12.4. RPL Target Option Registry . . . . . . . . . . . . . . . 36 12.4. RPL Target Option Flags Registry
12.5. New Subregistry for RPL Non-Rejection Status values . . 37 12.5. New Subregistry for RPL Non-Rejection Status Values
12.6. New Subregistry for RPL Rejection Status values . . . . 37 12.6. New Subregistry for RPL Rejection Status Values
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38 13. References
14. Normative References . . . . . . . . . . . . . . . . . . . . 38 13.1. Normative References
15. Informative References . . . . . . . . . . . . . . . . . . . 39 13.2. Informative References
Appendix A. Example Compression . . . . . . . . . . . . . . . . 41 Appendix A. Example Compression
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42 Acknowledgments
Authors' Addresses
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 "RPL: IPv6 Routing Protocol for Low-Power and Lossy
Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services Networks" [RFC6550] to provide routing services for IPv6 [RFC8200]
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
of topological knowledge that needs to be installed and maintained in amount of topological knowledge that needs to be installed and
each node, and does not require convergence to avoid micro-loops. maintained in 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 path stretch (see [RFC6687]), whereby routing is only allows a path stretch (see [RFC6687]), whereby routing is only
performed along a Destination-Oriented Directed Acyclic Graph (DODAG) performed along a Destination-Oriented Directed Acyclic Graph (DODAG)
that is optimized to reach a Root node, as opposed to along the that is optimized to reach a root node, as opposed to along the
shortest path between 2 peers, whatever that would mean in a given shortest path between two peers, whatever that would mean in a given
LLN. This trades the quality of peer-to-peer (P2P) paths for a LLN. This trades the quality of peer-to-peer (P2P) paths for a
vastly reduced amount of control traffic and routing state that would vastly reduced amount of control traffic and routing state that would
be required to operate an any-to-any shortest path protocol. be required to operate an any-to-any shortest-path protocol.
Additionally, broken routes may be fixed lazily and on-demand, based Additionally, broken routes may be fixed lazily and on demand, based
on dataplane inconsistency discovery, which avoids wasting energy in on data-plane inconsistency discovery, which avoids wasting energy in
the proactive repair of unused paths. the proactive repair of unused paths.
For many of the nodes, though not all, the DODAG provides multiple For many of the nodes, though not all, the 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 installs the routes proactively, but to adapt to fuzzy
physical topology cannot be expected to reach a stable state, with a connectivity -- whereby the physical topology cannot be expected to
lazy control that creates the routes proactively, but may only fix reach a stable state -- it uses a lazy route maintenance operation
them reactively, upon actual traffic. The result is that RPL that may only fix them reactively, upon actual traffic. The result
provides reachability for most of the LLN nodes, most of the time, is that RPL provides reachability for most of the LLN nodes, most of
but may not converge in the classical sense. the time, but may not converge in the classical sense.
RPL can be deployed in conjunction with IPv6 Neighbor Discovery (ND) RPL can be deployed in conjunction with IPv6 Neighbor Discovery (ND)
[RFC4861] [RFC4862] and 6LoWPAN ND [RFC6775] [RFC8505] to maintain [RFC4861] [RFC4862] and IPv6 over Low-Power Wireless Personal Area
reachability within a Non-Broadcast Multiple-Access (NBMA) Multi-Link Network (6LoWPAN) ND [RFC6775] [RFC8505] to maintain reachability
subnet. within a Non-Broadcast Multi-Access (NBMA) multi-link subnet.
In that mode, IPv6 addresses are advertised individually as host In that mode, IPv6 addresses are advertised individually as host
routes. Some nodes may act as routers and participate in the routes. Some nodes may act as routers and participate in the
forwarding operations whereas others will only receive/originate forwarding operations, whereas others will only receive/originate
packets, acting as hosts in the data-plane. In [RFC6550] terms, an packets, acting as hosts in the data plane. Per the terminology of
IPv6 host [RFC8504] that is reachable over the RPL network is called [RFC6550], an IPv6 host [RFC8504] that is reachable over the RPL
a leaf. network is called a "leaf".
Section 2 of [USEofRPLinfo] defines the terms RPL leaf, RPL-Aware- Section 2 of [RFC9008] defines the terms "RPL leaf", "RPL-Aware Leaf"
leaf (RAL) and RPL-Unaware Leaf (RUL). A RPL leaf is a host attached (RAL), and "RPL-Unaware Leaf" (RUL). A RPL leaf is a host attached
to one or more RPL router(s); as such, it relies on the RPL router(s) to one or more RPL routers; as such, it relies on the RPL router(s)
to forward its traffic across the RPL domain but does not forward to forward its traffic across the RPL domain but does not forward
traffic from another node. As opposed to the RAL, the RUL does not traffic from another node. As opposed to the RAL, the RUL does not
participate to RPL, and relies on its RPL router(s) also to inject participate in RPL and relies on its RPL router(s) to also inject the
the routes to its IPv6 addresses in the RPL domain. routes to its IPv6 addresses in the RPL domain.
A RUL may be unable to participate because it is very energy- A RUL may be unable to participate because it is very energy
constrained, code-space constrained, or because it would be unsafe to constrained or code-space constrained, or because it would be unsafe
let it inject routes in RPL. Using 6LoWPAN ND as opposed to RPL as to let it inject routes in RPL. Using 6LoWPAN ND as opposed to RPL
the host-to-router interface limits the surface of the possible as the host-to-router interface limits the surface of the possible
attacks by the RUL against the RPL domain. If all RULs and RANs use attacks by the RUL against the RPL domain. If all RULs and RPL-Aware
6LoWPAN ND for Neighbor Discovery, it is also possible to protect the Nodes (RANs) use 6LoWPAN ND for the neighbor discovery process, it is
address ownership of all nodes, including the RULs. also possible to protect the address ownership of all nodes,
including the RULs.
This document specifies how the router injects the host routes in the This document specifies how the router injects the host routes in the
RPL domain on behalf of the RUL. Section 5 details how the RUL can RPL domain on behalf of the RUL. Section 5 details how the RUL can
leverage 6LoWPAN ND to obtain the routing services from the router. leverage 6LoWPAN ND to obtain the routing services from the router.
In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-Aware In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-aware
router is also a 6LoWPAN Router (6LR). Using the 6LoWPAN ND Address router is also a 6LoWPAN Router (6LR). Using the 6LoWPAN ND Address
Registration mechanism, the RUL signals that the router must inject a Registration mechanism, the RUL signals that the router must inject a
host route for the Registered Address. host route for the Registered Address.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | <------------- 6LBR / RPL Root | | <------------- 6LBR / RPL DODAG Root
+-----+ ^ +-----+ ^
| | | |
o o o o | RPL o o o o | RPL
o o o o o o o o | o o o o o o o o |
o o o o o o o o o o | + o o o o o o o o o o | +
o o o o o o o | o o o o o o o |
o o o o o o o o o | 6LoWPAN ND o o o o o o o o o | 6LoWPAN ND
o o o o o o | o o o o o o |
o o o o v o o o o v
o o o <------------- 6LR / RPL Border router o o o <------------- 6LR / RPL Border Router
^ ^
| 6LoWPAN ND only | 6LoWPAN ND only
v v
u <------------- 6LN / RPL-Unaware Leaf u <------------- 6LN / RPL-Unaware Leaf
Figure 1: Injecting Routes on behalf of RULs Figure 1: Injecting Routes on Behalf of RULs
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 RUL is described in section 4.1 of [USEofRPLinfo]. serving a RUL is described in Section 4.1.1 of [RFC9008].
Examples of possible RULs include severely energy constrained sensors Examples of possible RULs include severely energy-constrained sensors
such as window smash sensor (alarm system), and kinetically powered such as window smash sensors (alarm system) and kinetically powered
light switches. Other applications of this specification may include light switches. Other applications of this specification may include
a smart grid network that controls appliances - such as washing a smart grid network that controls appliances -- such as washing
machines or the heating system - in the home. Appliances may not machines or the heating system -- in the home. Appliances may not
participate to the RPL protocol operated in the Smartgrid network but participate in the RPL protocol operated in the smart grid network
can still interact with the Smartgrid for control and/or metering. but can still interact with the smart grid for control and/or
metering.
This specification can be deployed incrementally in a network that This specification can be deployed incrementally in a network that
implements [USEofRPLinfo]. Only the Root and the 6LRs that connect implements [RFC9008]. Only the root and the 6LRs that connect the
the RULs need to be upgraded. The RPL routers on path will only see RULs need to be upgraded. The RPL routers on the path will only see
unicast IPv6 traffic between the Root and the 6LR. unicast IPv6 traffic between the root and the 6LR.
This document is organized as follows: This document is organized as follows:
* Section 3 and Section 4 present in a non-normative fashion the * Sections 3 and 4 present in a non-normative fashion the salient
salient aspects of RPL and 6LoWPAN ND, respectively, that are aspects of RPL and 6LoWPAN ND, respectively, that are leveraged in
leveraged in this specification to provide connectivity to a 6LN this specification to provide connectivity to a 6LN acting as a
acting as a RUL across a RPL network. RUL across a RPL network.
* Section 5 lists the requirements that a RUL needs to match in * Section 5 lists the requirements that a RUL needs to match in
order to be served by a RPL router that complies with this order to be served by a RPL router that complies with this
specification. specification.
* Section 6 presents the changes made to [RFC6550]; a new behavior * Section 6 presents the changes made to [RFC6550]; a new behavior
is introduced whereby the 6LR advertises the 6LN's addresses in a is introduced whereby the 6LR advertises the 6LN's addresses in a
RPL DAO message based on the ND registration by the 6LN, and the RPL Destination Advertisement Object (DAO) message based on the ND
RPL root performs the EDAR/EDAC exchange with the 6LoWPAN Border registration by the 6LN, and the RPL DODAG root performs the
Router (6LBR) on behalf of the 6LR; modifications are introduced Extended Duplicate Address Request / Extended Duplicate Address
to some RPL options and to the RPL Status to facilitate the Confirmation (EDAR/EDAC) exchange with the 6LoWPAN Border Router
integration of the protocols. (6LBR) on behalf of the 6LR; modifications are introduced to some
RPL options and to the RPL Status to facilitate the integration of
the protocols.
* Section 7 presents the changes made to [EFFICIENT-NPDAO]; the use * Section 7 presents the changes made to [RFC9009]; the use of the
of the DCO message is extended to the Non-Storing MOP to report Destination Cleanup Object (DCO) message is extended to the Non-
asynchronous issues from the Root to the 6LR. Storing RPL Mode of Operation (MOP) to report asynchronous issues
from the root to the 6LR.
* Section 8 presents the changes made to [RFC6775] and [RFC8505]; * Section 8 presents the changes made to [RFC6775] and [RFC8505];
The range of the ND status codes is reduced down to 64 values, and the range of the Address Registration Option / Extended Address
the remaining bits in the original status field are now reserved. Registration Option (ARO/EARO) Status values is reduced to 64
values, and the remaining bits in the original status field are
now reserved.
* Section 9 and Section 10 present the operation of this * Sections 9 and 10 present the operation of this specification for
specification for unicast and multicast flows, respectively, and unicast and multicast flows, respectively, and Section 11 presents
Section 11 presents associated security considerations. associated security considerations.
2. Terminology 2. Terminology
2.1. Requirements Language 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
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. Glossary 2.2. Glossary
This document uses the following acronyms: This document uses the following abbreviations:
6BBR: 6LoWPAN Backbone Router
6CIO: 6LoWPAN Capability Indication Option 6CIO: 6LoWPAN Capability Indication Option
6LN: 6LoWPAN Node (a Low Power host or router) 6LBR: 6LoWPAN Border Router
6LR: 6LoWPAN router 6LN: 6LoWPAN Node (a low-power host or router)
6LBR: 6LoWPAN Border router 6LoRH: 6LoWPAN Routing Header
(E)ARO: (Extended) Address Registration Option 6LoWPAN: IPv6 over Low-Power Wireless Personal Area Network
(E)DAR: (Extended) Duplicate Address Request 6LR: 6LoWPAN Router
(E)DAC: (Extended) Duplicate Address Confirmation AP-ND: Address-Protected Neighbor Discovery
ARO: Address Registration Option
DAC: Duplicate Address Confirmation
DAD: Duplicate Address Detection DAD: Duplicate Address Detection
DAO: Destination Advertisement Object (a RPL message) DAO: Destination Advertisement Object (a RPL message)
DAR: Duplicate Address Request
DCO: Destination Cleanup Object (a RPL message) DCO: Destination Cleanup Object (a RPL message)
DIO: DODAG Information Object (a RPL message) DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph DODAG: Destination-Oriented Directed Acyclic Graph
EARO: Extended Address Registration Option
EDAC: Extended Duplicate Address Confirmation
EDAR: Extended Duplicate Address Request
EUI: Extended Unique Identifier
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
MLD: Multicast Listener Discovery
MOP: RPL Mode of Operation MOP: RPL Mode of Operation
NA: Neighbor Advertisement NA: Neighbor Advertisement
NBMA: Non-Broadcast Multi-Access
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery ND: Neighbor Discovery
NS: Neighbor Solicitation NS: Neighbor Solicitation
RA: router Advertisement PIO: Prefix Information Option
RA: Router Advertisement
RAL: RPL-Aware Leaf
RAN: RPL-Aware Node (either a RPL router or a RPL-Aware Leaf)
RH3: Routing Header for IPv6 (type 3)
ROVR: Registration Ownership Verifier ROVR: Registration Ownership Verifier
RPI: RPL Packet Information RPI: RPL Packet Information
RAL: RPL-aware Leaf RPL: Routing Protocol for Low-Power and Lossy Networks
RAN: RPL-Aware Node (either a RPL router or a RPL-aware Leaf)
RUL: RPL-Unaware Leaf RUL: RPL-Unaware Leaf
SRH: Source-Routing Header SAVI: Source Address Validation Improvement
SLAAC: Stateless Address Autoconfiguration
SRH: Source Routing Header
TID: Transaction ID (a sequence counter in the EARO) TID: Transaction ID (a sequence counter in the EARO)
TIO: Transit Information Option TIO: Transit Information Option
2.3. References 2.3. Related Documents
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 the terms provided in, "Terms Used in Routing for
and Lossy Networks (LLNs)" [RFC7102]. A glossary of classical Low-Power and Lossy Networks" [RFC7102]. A glossary of classical
6LoWPAN acronyms is given in Section 2.2. Other terms in use in LLNs 6LoWPAN abbreviations is given in Section 2.2. Other terms in use in
are found in "Terminology for Constrained-Node Networks" [RFC7228]. LLNs are found in "Terminology for Constrained-Node Networks"
This specification uses the terms 6LN and 6LR to refer specifically [RFC7228]. This specification uses the terms "6LN" and "6LR" to
to nodes that implement the 6LN and 6LR roles in 6LoWPAN ND and does refer specifically to nodes that implement the 6LN and 6LR roles in
not expect other functionality such as 6LoWPAN Header Compression 6LoWPAN ND and does not expect other functionality such as 6LoWPAN
[RFC6282] from those nodes. Header Compression [RFC6282] from those nodes.
"RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by "RPL", "RPI", "RPL Instance" (indexed by a RPLInstanceID), "up", and
a RPLInstanceID), "up", "down" are defined in "RPL: IPv6 Routing "down" are defined in "RPL: IPv6 Routing Protocol for Low-Power and
Protocol for Low-Power and Lossy Networks" [RFC6550]. The RPI is the Lossy Networks" [RFC6550]. The RPI is the abstract information that
abstract information that RPL defines to be placed in data packets, RPL defines to be placed in data packets, e.g., as the RPL Option
e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. [RFC6553] within the IPv6 Hop-By-Hop Header. By extension, the term
By extension, the term "RPI" is often used to refer to the RPL Option "RPI" is often used to refer to the RPL Option itself. The DAO and
itself. The Destination Advertisement Object (DAO) and DODAG DIO messages are also specified in [RFC6550]. The DCO message is
Information Object (DIO) messages are also specified in [RFC6550]. defined in [RFC9009].
The Destination Cleanup Object (DCO) message is defined in
[EFFICIENT-NPDAO].
This document uses the terms RPL-Unaware Leaf (RUL), RPL-Aware Node This document uses the terms "RUL", "RAN", and "RAL" consistently
(RAN) and RPL aware Leaf (RAL) consistently with [USEofRPLinfo]. A with [RFC9008]. A RAN is either a RAL or a RPL router. As opposed
RAN is either a RAL or a RPL router. As opposed to a RUL, a RAN to a RUL, a RAN manages the reachability of its addresses and
manages the reachability of its addresses and prefixes by injecting prefixes by injecting them in RPL by itself.
them in RPL by itself.
In this document, readers will encounter terms and concepts that are In this document, readers will encounter terms and concepts that are
discussed in the following documents: discussed in the following documents:
Classical IPv6 ND: "Neighbor Discovery for IP version 6" [RFC4861] Classical IPv6 ND: "Neighbor Discovery for IP version 6 (IPv6)"
and "IPv6 Stateless Address Autoconfiguration" [RFC4862], [RFC4861] and "IPv6 Stateless Address Autoconfiguration"
[RFC4862],
6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power 6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power
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 IPv6 over Low-Power
Networks [RFC6775], "Registration Extensions for 6LoWPAN Neighbor Wireless Personal Area Networks (6LoWPANs)" [RFC6775],
Discovery" [RFC8505], "Address Protected Neighbor Discovery for "Registration Extensions for IPv6 over Low-Power Wireless Personal
Low-power and Lossy Networks" [RFC8928], and "IPv6 Backbone Area Network (6LoWPAN) Neighbor Discovery" [RFC8505],
Router" [RFC8929]. "Address-Protected Neighbor Discovery for Low-Power and Lossy
Networks" [RFC8928], and "IPv6 Backbone Router" [RFC8929].
3. RPL External Routes and Dataplane Artifacts 3. RPL External Routes and Data-Plane Artifacts
RPL was initially designed to build stub networks whereby the only RPL was initially designed to build stub networks whereby the only
border router would be the RPL Root (typically collocated with the border router would be the RPL DODAG root (typically co-located with
6LBR) and all the nodes in the stub would be RPL-Aware. But the 6LBR) and all the nodes in the stub would be RPL aware. But
[RFC6550] was also prepared to be extended for external routes [RFC6550] was also prepared to be extended for external routes
(targets in RPL parlance) with the External 'E' flag in the Transit ("targets" in RPL parlance), via the External ('E') flag in the
Information Option (TIO). External targets enable to reach Transit Information Option (TIO). External targets provide the
destinations that are outside the RPL domain and connected to the RPL ability to reach destinations that are outside the RPL domain and
domain via RPL border routers that are not the Root. Section 4.1 of connected to the RPL domain via RPL border routers that are not the
[USEofRPLinfo] provides a set of rules summarized below that must be root. Section 4.1 of [RFC9008] provides a set of rules (summarized
followed for routing packets to and from an external destination. A below) that must be followed for routing packets to and from an
RUL is a special case of an external target that is also a host external destination. A RUL is a special case of an external target
directly connected to the RPL domain. that is also a host directly connected to the RPL domain.
A 6LR that acts as a border router for external routes advertises A 6LR that acts as a border router for external routes advertises
them using Non-Storing Mode DAO messages that are unicast directly to them using Non-Storing mode DAO messages that are unicast directly to
the Root, even if the DODAG is operated in Storing Mode. Non-Storing the root, even if the DODAG is operated in Storing mode. Non-Storing
Mode routes are not visible inside the RPL domain and all packets are mode routes are not visible inside the RPL domain, and all packets
routed via the Root. The RPL Root tunnels the data packets directly are routed via the root. The RPL DODAG root tunnels the data packets
to the 6LR that advertised the external route, which decapsulates and directly to the 6LR that advertised the external route, which
forwards the original (inner) packets. decapsulates and forwards the original (inner) packets.
The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6 The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6
encapsulated packets appear as normal traffic to the intermediate encapsulated packets appear as normal traffic to the intermediate
routers. The support of external routes only impacts the Root and routers. Support of external routes only impacts the root and the
the 6LR. It can be operated with legacy intermediate routers and 6LR. It can be operated with legacy intermediate routers and does
does not add to the amount of state that must be maintained in those not add to the amount of state that must be maintained in those
routers. A RUL is an example of a destination that is reachable via routers. A RUL is an example of a destination that is reachable via
an external route that happens to be also a host route. an external route that happens to also be a host route.
The RPL data packets typically carry a Hop-by-Hop Header with a RPL The RPL data packets typically carry a Hop-by-Hop Header with a RPL
Option [RFC6553] that contains the Packet Information (RPI) defined Option [RFC6553] that contains the RPI (the RPL Packet Information,
in section 11.2 of [RFC6550]. Unless the RUL already placed a RPL as defined in Section 11.2 of [RFC6550]). Unless the RUL already
Option in outer header chain, the packets from and to the RUL are placed a RPL Option in the outer header chain, the packets from and
encapsulated using an IPv6-in-IPv6 tunnel between the Root and the to the RUL are encapsulated using an IPv6-in-IPv6 tunnel between the
6LR that serves the RUL (see sections 7 and 8 of [USEofRPLinfo] for root and the 6LR that serves the RUL (see Sections 7 and 8 of
details). If the packet from the RUL has an RPI, the 6LR as a RPL [RFC9008] for details). If the packet from the RUL has an RPI, the
border router rewrites the RPI to indicate the selected Instance and 6LR acting as a RPL border router rewrites the RPI to indicate the
set the flags, but it does not need to encapsulate the packet (see selected RPL Instance and set the flags, but it does not need to
Section 9.2.2) . encapsulate the packet (see Section 9.2.2).
In Non-Storing Mode, packets going down carry a Source Routing Header In Non-Storing mode, packets going down the DODAG carry a Source
(SRH). The IPv6-in-IPv6 encapsulation, the RPI and the SRH are Routing Header (SRH). The IPv6-in-IPv6 encapsulation, the RPI, and
collectively called the "RPL artifacts" and can be compressed using the SRH are collectively called the "RPL artifacts" and can be
[RFC8138]. Appendix A presents an example compressed format for a compressed using the method defined in [RFC8138]. Appendix A
packet forwarded by the Root to a RUL in a Storing Mode DODAG. 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 inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it, artifacts, e.g., an RPI if the original packet was generated with it,
and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the and an SRH in a Non-Storing mode DODAG. [RFC9008] expects the RUL to
RUL to support the basic "IPv6 Node Requirements" [RFC8504] and in support the basic IPv6 node requirements per [RFC8504] and, in
particular the mandates in Sections 4.2 and 4.4 of [RFC8200]. As particular, the mandates in Sections 4.2 and 4.4 of [RFC8200]. As
such, the RUL is expected to ignore the RPL artifacts that may be such, the RUL is expected to ignore the RPL artifacts that may be
left over, either an SRH with zero Segments Left or a RPL Option in left over -- either an SRH whose Segments Left is zero or a RPL
the Hop-by-Hop Header, which can be skipped when not recognized, see Option in the Hop-by-Hop Header (which can be skipped when not
Section 5 for more. recognized; see Section 5.3 for details).
A RUL is not expected to support the compression method defined in A RUL is not expected to support the compression method defined in
[RFC8138]. For that reason, the border router (the 6LR here) [RFC8138]. For that reason, the border router (the 6LR here)
uncompresses the packet before forwarding it over an external route uncompresses the packet before forwarding it over an external route
to a RUL [USEofRPLinfo]. to a RUL [RFC9008].
4. 6LoWPAN Neighbor Discovery 4. 6LoWPAN Neighbor Discovery
This section goes through the 6LoWPAN ND mechanisms that this This section goes through the 6LoWPAN ND mechanisms that this
specification leverages, as a non-normative reference to the reader. specification leverages, as a non-normative reference to the reader.
The full normative text is to be found in [RFC6775], [RFC8505], and The full normative text is to be found in [RFC6775], [RFC8505], and
[RFC8928]. [RFC8928].
4.1. RFC 6775 Address Registration 4.1. Address Registration per RFC 6775
The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861] The classical 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 address lookup) and Duplicate
Detection (DAD). Address Detection (DAD).
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
adapts IPv6 ND for operations over energy-constrained LLNs. The main Personal Area Networks (6LoWPANs)" [RFC6775] adapts IPv6 ND for
functions of [RFC6775] are to proactively establish the Neighbor operations over energy-constrained LLNs. The main functions of
Cache Entry (NCE) in the 6LR and to prevent address duplication. To [RFC6775] are to proactively establish the Neighbor Cache Entry (NCE)
that effect, [RFC6775] introduces a new unicast Address Registration in the 6LR and to prevent address duplication. To that effect,
mechanism that contributes to reducing the use of multicast messages [RFC6775] introduces a unicast Address Registration mechanism that
compared to the classical IPv6 ND protocol. contributes to reducing the use of multicast messages compared to the
classical IPv6 ND protocol.
[RFC6775] defines a new Address Registration Option (ARO) that is [RFC6775] also introduces the Address Registration Option (ARO),
carried in the unicast Neighbor Solicitation (NS) and Neighbor which is carried in the unicast Neighbor Solicitation (NS) and
Advertisement (NA) messages between the 6LoWPAN Node (6LN) and the Neighbor Advertisement (NA) messages between the 6LoWPAN Node (6LN)
6LoWPAN router (6LR). It also defines the Duplicate Address Request and the 6LoWPAN router (6LR). It also defines the Duplicate Address
(DAR) and Duplicate Address Confirmation (DAC) messages between the Request (DAR) and Duplicate Address Confirmation (DAC) messages
6LR and the 6LBR). In an LLN, the 6LBR is the central repository of between the 6LR and the 6LBR). In an LLN, the 6LBR is the central
all the Registered Addresses in its domain and the source of truth repository of all the Registered Addresses in its domain and the
for uniqueness and ownership. source of truth for uniqueness and ownership.
4.2. RFC 8505 Extended Address Registration 4.2. Extended Address Registration per RFC 8505
"Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505] "Registration Extensions for IPv6 over Low-Power Wireless Personal
updates RFC 6775 into a generic Address Registration mechanism that Area Network (6LoWPAN) Neighbor Discovery" [RFC8505] updates RFC 6775
can be used to access services such as routing and ND proxy. To that with a generic Address Registration mechanism that can be used to
access services such as routing and ND proxy functions. To that
effect, [RFC8505] defines the Extended Address Registration Option effect, [RFC8505] defines the Extended Address Registration Option
(EARO), shown in Figure 2: (EARO), as shown in Figure 2:
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 (ROVR) ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: EARO Option Format Figure 2: EARO Format
4.2.1. 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 set to 0, reachability for the Registered Address. If the R flag is set to 0,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means. In a RPL network, this means that either it Address by other means. In a RPL network, this means that either it
is a RAN that injects the route by itself or that it uses another RPL is a RAN that injects the route by itself or it uses another RPL
router for reachability services. router for reachability services.
This document specifies how the R Flag is used in the context of RPL. This document specifies how the R flag is used in the context of RPL.
A RPL leaf that implements the 6LN functionality from [RFC8505] A RPL leaf that implements the 6LN functionality from [RFC8505]
requires reachability services for an IPv6 address if and only if it requires reachability services for an IPv6 address if and only if it
sets the R Flag in the NS(EARO) used to register the address to a 6LR sets the R flag in the NS(EARO) used to register the address to a 6LR
acting as a RPL border router. Upon receiving the NS(EARO), the RPL acting as a RPL border router. Upon receiving the NS(EARO), the RPL
router generates a DAO message for the Registered Address if and only router generates a DAO message for the Registered Address if and only
if the R flag is set to 1. if the R flag is set to 1.
Section 9.2 specifies additional operations when R flag is set to 1 Section 9.2 specifies additional operations when the R flag is set to
in an EARO that is placed either in an NS or an NA message. 1 in an EARO that is placed in either an NS message or an NA message.
4.2.2. TID, "I" Field and Opaque Fields 4.2.2. TID, "I" Field, and Opaque Field
When the T Flag is set to 1, the EARO includes a sequence counter When the T flag is set to 1, the EARO includes a sequence counter
called Transaction ID (TID), that is needed to fill the Path Sequence called the "Transaction ID" (TID), which is needed to fill the Path
Field in the RPL Transit Option. This is the reason why the support Sequence field in the RPL Transit Information Option (TIO). For this
of [RFC8505] by the RUL, as opposed to only [RFC6775], is a reason, support of [RFC8505] by the RUL, as opposed to only
prerequisite for this specification); this requirement is fully [RFC6775], is a prerequisite for this specification; this requirement
explained in Section 5.1. The EARO also transports an Opaque field is fully explained in Section 5.1. The EARO also transports an
and an associated "I" field that describes what the Opaque field Opaque field and an associated "I" field that describes what the
transports and how to use it. Opaque field transports and how to use it.
Section 9.2.1 specifies the use of the "I" field and the Opaque field Section 9.2.1 specifies the use of the "I" field and the Opaque field
by a RUL. by a RUL.
4.2.3. Route Ownership Verifier 4.2.3. Route Ownership Verifier
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, which has a variable length of 64 to 256 bits.
ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was The ROVR replaces the 64-bit Extended Unique Identifier (EUI-64) in
used to identify uniquely an Address Registration with the Link-Layer the ARO [RFC6775], which was used to uniquely identify an Address
address of the owner but provided no protection against spoofing. Registration with the link-layer 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" [RFC8928] leverages the ROVR field as a cryptographic proof Networks" [RFC8928] leverages the ROVR field as a cryptographic proof
of ownership to prevent a rogue third party from registering an of ownership to prevent a rogue third party from registering an
address that is already owned. The use of ROVR field enables the 6LR address that is already owned. The use of the ROVR field enables the
to block traffic that is not sourced at an owned address. 6LR to block traffic that is not sourced at an owned address.
This specification does not address how the protection by [RFC8928] This specification does not address how the protection offered by
could be extended for use in RPL. On the other hand, it adds the [RFC8928] could be extended for use in RPL. On the other hand, it
ROVR to the DAO to build the proxied EDAR at the Root (see adds the ROVR to the DAO to build the proxied EDAR at the root (see
Section 6.1), which means that nodes that are aware of the host route Section 6.1), which means that nodes that are aware of the host route
are also aware of the ROVR associated to the Target Address. are also aware of the ROVR associated to the Target Address.
4.3. RFC 8505 Extended DAR/DAC 4.3. EDAR/EDAC per RFC 8505
[RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to [RFC8505] updates the DAR/DAC messages to EDAR/EDAC messages to carry
carry the ROVR field. The EDAR/EDAC exchange takes place between the the ROVR field. The EDAR/EDAC exchange takes place between the 6LR
6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN and the 6LBR. It is triggered by an NS(EARO) message from a 6LN to
to create, refresh, and delete the corresponding state in the 6LBR. create, refresh, and delete the corresponding state in the 6LBR. The
The exchange is protected by the retry mechanism specified in exchange is protected by the retry mechanism specified in
Section 8.2.6 of [RFC6775], though in an LLN, a duration longer than Section 8.2.6 of [RFC6775], though in an LLN, a duration longer than
the default value of the RetransTimer (RETRANS_TIMER) [RFC4861] of 1 the default value of the RetransTimer (RETRANS_TIMER) [RFC4861] of 1
second may be necessary to cover the round trip delay between the 6LR second may be necessary to cover the round-trip delay between the 6LR
and the 6LBR. 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 8 in the 6LBR on behalf of the 6LR, as illustrated in Figure 8 in
Section 9.1. Section 9.1.
4.3.1. RFC 7400 Capability Indication Option 4.3.1. Capability Indication Option per RFC 7400
"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), which 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: The node is a 6LR.
E: Node is an IPv6 ND Registrar -- i.e., it supports registrations E: The node is an IPv6 ND Registrar -- i.e., it supports
based on EARO. registrations based on EARO.
P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that P: The node is a Routing Registrar -- i.e., an IPv6 ND Registrar
also provides reachability services for the Registered Address. that also provides reachability services for the Registered
Address.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 1 | Reserved |D|L|B|P|E|G| | Type | Length = 1 | Reserved |D|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: 6CIO flags Figure 3: 6CIO Flags
A 6LR that provides reachability services for a RUL in a RPL network A 6LR that provides reachability services for a RUL in a RPL network
as specified in this document includes a 6CIO in its RA messages and as specified in this document includes a 6CIO in its RA messages and
set the L, P and E flags to 1 as prescribed by [RFC8505]; this is set the L, P, and E flags to 1 as prescribed by [RFC8505]; this is
fully explained in Section 9.2. fully explained in Section 9.2.
5. Requirements on the RPL-Unware leaf 5. Requirements for the RPL-Unaware Leaf
This document describes how RPL routing can be extended to reach a This document describes how RPL routing can be extended to reach a
RUL. This section specifies the minimal RPL-independent RUL. This section specifies the minimal RPL-independent
functionality that the RUL needs to implement to obtain routing functionality that the RUL needs to implement in order to obtain
services for its addresses. routing services for its addresses.
5.1. Support of 6LoWPAN ND 5.1. Support of 6LoWPAN ND
To obtain routing services from a router that implements this To obtain routing services from a router that implements this
specification, a RUL needs to implement [RFC8505] and sets the "R" specification, a RUL needs to implement [RFC8505] and sets the "R"
and "T" flags in the EARO to 1 as discussed in Section 4.2.1 and and "T" flags in the EARO to 1 as discussed in Sections 4.2.1 and
Section 4.2.2, respectively. Section 9.2.1 specifies new behaviors 4.2.2, respectively. Section 9.2.1 specifies new behaviors for the
for the RUL, e.g., when the R Flag set to 1 in a NS(EARO) is not RUL, e.g., when the R flag set to 1 in an NS(EARO) is not echoed in
echoed in the NA(EARO), which indicates that the route injection the NA(EARO), which indicates that the route injection failed.
failed.
The RUL is expected to request routing services from a router only if The RUL is expected to request routing services from a router only if
that router originates RA messages with a 6CIO that has the L, P, and that router originates RA messages with a 6CIO that has the L, P, and
E flags all set to 1 as discussed in Section 4.3.1, unless configured E flags all set to 1 as discussed in Section 4.3.1, unless configured
to do so. It is suggested that the RUL also implements [RFC8928] to to do so. It is suggested that the RUL also implement [RFC8928] to
protect the ownership of its addresses. protect the ownership of its addresses.
A RUL that may attach to multiple 6LRs is expected to prefer those A RUL that may attach to multiple 6LRs is expected to prefer those
that provide routing services. The RUL needs to register to all the that provide routing services. The RUL needs to register with all
6LRs from which it desires routing services. the 6LRs from which it desires routing services.
Parallel Address Registrations to several 6LRs should be performed in Parallel Address Registrations to several 6LRs should be performed in
a rapid sequence, using the same EARO for the same Address. Gaps a rapid sequence, using the same EARO for the same address. Gaps
between the Address Registrations will invalidate some of the routes between the Address Registrations will invalidate some of the routes
till the Address Registration finally shows on those routes. until the Address Registration finally shows on those routes.
[RFC8505] introduces error Status values in the NA(EARO) which can be [RFC8505] introduces error Status values in the NA(EARO) that can be
received synchronously upon an NS(EARO) or asynchronously. The RUL received synchronously upon an NS(EARO) or asynchronously. The RUL
needs to support both cases and refrain from using the address when needs to support both cases and refrain from using the address when
the Status value indicates a rejection (see Section 6.3). the Status value indicates a rejection (see Section 6.3).
5.2. Support of IPv6 Encapsulation 5.2. Support of IPv6 Encapsulation
Section 2.1 of [USEofRPLinfo] defines the rules for tunneling either Section 4.1.1 of [RFC9008] defines the rules for signaling an
to the final destination (e.g., a RUL) or to its attachment router external destination (e.g., a RUL) and tunneling to its attachment
(designated as 6LR). In order to terminate the IPv6-in-IPv6 tunnel, router (designated as a 6LR). In order to terminate the IPv6-in-IPv6
the RUL, as an IPv6 host, would have to be capable of decapsulating tunnel, the RUL, as an IPv6 host, would have to be capable of
the tunneled packet and either drop the encapsulated packet if it is decapsulating the tunneled packet and either drop the encapsulated
not the final destination, or pass it to the upper layer for further packet if it is not the final destination or pass it to the upper
processing. As indicated in section 4.1 of [USEofRPLinfo], this is layer for further processing. As indicated in Section 4.1 of
not mandated by [RFC8504], and the IPv6-in-IPv6 tunnel from the Root [RFC9008], this is not mandated by [RFC8504], and the IPv6-in-IPv6
is terminated at the parent 6LR. It is thus not necessary for a RUL tunnel from the root is terminated at the parent 6LR. It is thus not
to support IPv6-in-IPv6 decapsulation. necessary for a RUL to support IPv6-in-IPv6 decapsulation.
5.3. Support of the Hop-by-Hop Header 5.3. Support of the Hop-by-Hop Header
A RUL is expected to process an Option Type in a Hop-by-Hop Header as A RUL is expected to process an Option Type in a Hop-by-Hop Header as
prescribed by section 4.2 of [RFC8200]. An RPI with an Option Type prescribed by Section 4.2 of [RFC8200]. An RPI with an Option Type
of 0x23 [USEofRPLinfo] is thus skipped when not recognized. of 0x23 [RFC9008] is thus skipped when not recognized.
5.4. Support of the Routing Header 5.4. Support of the Routing Header
A RUL is expected to process an unknown Routing Header Type as A RUL is expected to process an unknown Routing Header Type as
prescribed by section 4.4 of [RFC8200]. This implies that the Source prescribed by Section 4.4 of [RFC8200]. This implies that the SRH,
Routing Header, which has a Routing Type of 3 [RFC6554], is ignored which has a Routing Type of 3 [RFC6554], is ignored when Segments
when the Segments Left is zero. When the Segments Left is non-zero, Left is zero. When Segments Left is non-zero, the RUL discards the
the RUL discards the packet and send an ICMP Parameter Problem, Code packet and sends an ICMP Parameter Problem message with Code 0 to the
0, message to the packet's Source Address, pointing to the packet's source address, pointing to the unrecognized Routing Type.
unrecognized Routing Type.
6. Enhancements to RFC 6550 6. Enhancements to RFC 6550
This document specifies a new behavior whereby a 6LR injects DAO This document specifies a new behavior whereby a 6LR injects DAO
messages for unicast addresses (see Section 9) and multicast messages for unicast addresses (see Section 9) and multicast
addresses (see Section 10) on behalf of leaves that are not aware of addresses (see Section 10) on behalf of leaves that are not aware of
RPL. The RUL addresses are exposed as external targets [RFC6550]. RPL. The RUL addresses are exposed as external targets [RFC6550].
Conforming to [USEofRPLinfo], an IPv6-in-IPv6 encapsulation between Conforming to [RFC9008], IPv6-in-IPv6 encapsulation between the 6LR
the 6LR and the RPL Root is used to carry the RPL artifacts and and the RPL DODAG root is used to carry the RPL artifacts and remove
remove them 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 lifetime value is used for both, and a single
single keep-alive message, the RPL DAO, traverses the RPL network. A keep-alive message, the RPL DAO, traverses the RPL network. Another
new behavior is introduced whereby the RPL Root proxies the EDAR new behavior is introduced whereby the RPL DODAG root proxies the
message to the 6LBR on behalf of the 6LR (see Section 8), for any EDAR message to the 6LBR on behalf of the 6LR (see Section 8), for
leaf node that implements the 6LN functionality in [RFC8505]. any leaf node that implements the 6LN functionality described in
[RFC8505].
Section 6.7.7 of [RFC6550] introduces the RPL Target Option, which Section 6.7.7 of [RFC6550] introduces the RPL Target option, which
can be used in RPL Control messages such as the DAO message to signal can be used in RPL control messages such as the DAO message to signal
a destination prefix. This document adds the capabilities to a destination prefix. This document adds capabilities for
transport the ROVR field (see Section 4.2.3) and the IPv6 Address of transporting the ROVR field (see Section 4.2.3) and the IPv6 address
the prefix advertiser when the Target is a shorter prefix. Their use of the prefix advertiser when the Target is a shorter prefix. Their
is signaled respectively by a new ROVR Size field being non-zero and use is signaled by a new ROVR Size field being non-zero and a new
a new "Advertiser address in Full" 'F' flag set to 1, see "Advertiser address in Full (F)" flag set to 1, respectively; see
Section 6.1. Section 6.1.
This specification defines a new flag, "Root Proxies EDAR/EDAC" (P), This specification defines a new flag, "Root Proxies EDAR/EDAC (P)",
in the RPL DODAG Configuration option, see Section 6.2. in the RPL DODAG Configuration option; see Section 6.2.
The RPL Status defined in section 6.5.1 of [RFC6550] for use in the Furthermore, this specification provides the ability to carry the
DAO-ACK message is extended to be placed in DCO messages EARO Status defined for 6LoWPAN ND in RPL DAO and DCO messages,
[EFFICIENT-NPDAO] as well. Furthermore, this specification enables embedded in a RPL Status; see Section 6.3.
to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO
messages, embedded in a RPL Status, see Section 6.3.
Section 12 of [RFC6550] details the RPL support for multicast flows Section 12 of [RFC6550] details RPL support for multicast flows when
when the RPLInstance is operated in the MOP of 3 ("Storing Mode of the RPL Instance is operated with a MOP setting of 3 ("Storing Mode
Operation with multicast support"). This specification extends the of Operation with multicast support"). This specification extends
RPL Root operation to proxy-relay the MLDv2 [RFC3810] operation the RPL DODAG root operation to proxy-relay the MLDv2 operation
between the RUL and the 6LR, see Section 10. [RFC3810] between the RUL and the 6LR; see Section 10.
6.1. Updated RPL Target Option 6.1. Updated RPL Target Option
This specification updates the RPL Target Option to transport the This specification updates the RPL Target option to transport the
ROVR that was also defined for 6LoWPAN ND messages. This enables the ROVR that was also defined for 6LoWPAN ND messages. This enables the
RPL Root to generate the proxied EDAR message to the 6LBR. RPL DODAG root to generate the proxied EDAR message to the 6LBR.
The Target Prefix of the RPL Target Option is left (high bit) The Target Prefix of the RPL Target option is left (high bit)
justified and contains the advertised prefix; its size may be smaller justified and contains the advertised prefix; its size may be smaller
than 128 when it indicates a Prefix route. The Prefix Length field than 128 when it indicates a prefix route. The Prefix Length field
signals the number of bits that correspond to the advertised Prefix; signals the number of bits that correspond to the advertised prefix;
it is 128 for a host route or less in the case of a Prefix route. it is 128 for a host route or less in the case of a prefix route.
This remains unchanged. This remains unchanged.
This specification defines the new 'F' flag. When it is set to 1, This specification defines the new 'F' flag. When it is set to 1,
the size of the Target Prefix field MUST be 128 bits and it MUST the size of the Target Prefix field MUST be 128 bits and it MUST
contain an IPv6 address of the advertising node taken from the contain an IPv6 address of the advertising node taken from the
advertised Prefix. In that case, the Target Prefix field carries two advertised prefix. In that case, the Target Prefix field carries two
distinct pieces of information: a route that can be a host route or a distinct pieces of information: a route that can be a host route or a
Prefix route depending on the Prefix Length, and an IPv6 address that prefix route, depending on the Prefix Length; and an IPv6 address
can be used to reach the advertising node and validate the route. that can be used to reach the advertising node and validate the
route.
If the 'F' flag is set to 0, the Target Prefix field can be shorter If the 'F' flag is set to 0, the Target Prefix field can be shorter
than 128 bits and it MUST be aligned to the next byte boundary after than 128 bits, and it MUST be aligned to the next byte boundary after
the end of the prefix. Any additional bits in the rightmost octet the end of the prefix. Any additional bits in the rightmost octet
are filled with padding bits. Padding bits are reserved and set to 0 are filled with padding bits. Padding bits are reserved and set to 0
as specified in section 6.7.7 of [RFC6550]. as specified in Section 6.7.7 of [RFC6550].
With this specification the ROVR is the remainder of the RPL Target With this specification, the ROVR is the remainder of the RPL Target
Option. The size of the ROVR is indicated in a new ROVR Size field option. The size of the ROVR is indicated in a new ROVR Size field
that is encoded to map one-to-one with the Code Suffix in the EDAR that is encoded to map one to one with the Code Suffix in the EDAR
message (see table 4 of [RFC8505]). The ROVR Size field is taken message (see Table 4 of [RFC8505]). The ROVR Size field is taken
from the flags field, which is an update to the RPL Target Option from the Flags field, which is an update to the "RPL Target Option
Flags IANA registry. Flags" IANA registry.
The updated format is illustrated in Figure 4. It is backward The updated format is illustrated in Figure 4. It is backward
compatible with the Target Option in [RFC6550]. It is recommended compatible with the Target option defined in [RFC6550]. It is
that the updated format be used as a replacement in new recommended that the updated format be used as a replacement in new
implementations in all MOPs in preparation for upcoming Route implementations in all MOPs in preparation for upcoming route
Ownership Validation mechanisms based on the ROVR, unless the device ownership validation mechanisms based on the ROVR, unless the device
or the network is so constrained that this is not feasible. or the network is so constrained that this is not feasible.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x05 | Option Length |F|X|Flg|ROVRsz | Prefix Length | | Type = 0x05 | Option Length |F|X|Flg|ROVRsz | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Target Prefix (Variable Length) | | Target Prefix (Variable Length) |
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier (ROVR) ... ... Registration Ownership Verifier (ROVR) ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Updated Target Option Figure 4: Updated Target Option
New fields: New fields:
F: 1-bit flag. Set to 1 to indicate that Target Prefix field F: 1-bit flag. Set to 1 to indicate that the Target Prefix field
contains the complete (128 bit) IPv6 address of the advertising contains the complete (128-bit) IPv6 address of the advertising
node. node.
X: 1-bit flag. Set to 1 to request that the Root performs a proxy X: 1-bit flag. Set to 1 to request that the root perform a proxy
EDAR/EDAC exchange. EDAR/EDAC exchange.
The 'X' flag can only be set to 1 if the DODAG is operating in The 'X' flag can only be set to 1 if the DODAG is operating in
Non-Storing Mode and if the Root sets the "Root Proxies EDAR/EDAC Non-Storing mode and if the root sets the "Root Proxies EDAR/EDAC
(P)" flag to 1 in the DODAG Configuration Option, see Section 6.2. (P)" flag to 1 in the DODAG Configuration option; see
Section 6.2.
The 'X' flag can be set for host routes to RULs and RANs; it can The 'X' flag can be set for host routes to RULs and RANs; it can
also be set for internal prefix routes if the 'F' flag is set, also be set for internal prefix routes if the 'F' flag is set,
using the node's address in the Target Prefix field to form the using the node's address in the Target Prefix field to form the
EDAR, but it cannot be used otherwise. EDAR, but it cannot be used otherwise.
Flg (Flags): The 2 bits remaining unused in the Flags field are Flg (Flags): The 2 bits remaining unused in the Flags field are
reserved for flags. The field MUST be initialized to zero by the reserved for flags. The field MUST be initialized to 0 by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
ROVRsz (ROVR Size): Indicates the Size of the ROVR. It MUST be set ROVRsz (ROVR Size): Indicates the size of the ROVR. It MUST be set
to 1, 2, 3, or 4, indicating a ROVR size of 64, 128, 192, or 256 to 1, 2, 3, or 4, indicating a ROVR size of 64, 128, 192, or 256
bits, respectively. bits, respectively.
If a legacy Target Option is used, then the value must remain 0, If a legacy Target option is used, then the value must remain 0,
as specified in [RFC6550]. as specified in [RFC6550].
In case of a value above 4, the size of the ROVR is undetermined In the case of a value above 4, the size of the ROVR is
and this node cannot validate the ROVR; an implementation SHOULD undetermined and this node cannot validate the ROVR; an
propagate the whole Target Option upwards as received to enable implementation SHOULD propagate the whole Target option upwards
the verification by an ancestor that would support the upgraded as received to enable the verification by an ancestor that would
ROVR. support the upgraded ROVR.
Registration Ownership Verifier (ROVR): This is the same field as in Registration Ownership Verifier (ROVR): This is the same field as in
the EARO, see [RFC8505] the EARO; see [RFC8505].
6.2. Additional Flag in the RPL DODAG Configuration Option 6.2. Additional Flag in the RPL DODAG Configuration Option
The DODAG Configuration Option is defined in Section 6.7.6 of The DODAG Configuration option is defined in Section 6.7.6 of
[RFC6550]. Its purpose is extended to distribute configuration [RFC6550]. Its purpose is extended to distribute configuration
information affecting the construction and maintenance of the DODAG, information affecting the construction and maintenance of the DODAG,
as well as operational parameters for RPL on the DODAG, through the as well as operational parameters for RPL on the DODAG, through the
DODAG. This Option was originally designed with 4 bit positions DODAG. This option was originally designed with four bit positions
reserved for future use as Flags. reserved for future use as flags.
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 = 0x04 |Opt Length = 14| |P| | |A| ... | | Type = 0x04 |Opt Length = 14| |P| | |A| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|4 bits | |4 bits |
Figure 5: DODAG Configuration Option (Partial View) Figure 5: DODAG Configuration Option (Partial View)
This specification defines a new flag "Root Proxies EDAR/EDAC" (P). This specification defines a new flag, "Root Proxies EDAR/EDAC (P)".
The 'P' flag is encoded in bit position 1 of the reserved Flags in The 'P' flag is encoded in bit position 1 of the reserved flags in
the DODAG Configuration Option (counting from bit 0 as the most the DODAG Configuration option (counting from bit 0 as the most
significant bit) and it is set to 0 in legacy implementations as significant bit), and it is set to 0 in legacy implementations as
specified respectively in Sections 20.14 and 6.7.6 of [RFC6550]. specified in Sections 20.14 and 6.7.6 of [RFC6550], respectively.
The 'P' flag is set to 1 to indicate that the Root performs the proxy The 'P' flag is set to 1 to indicate that the root performs the proxy
operation, which implies that it supports this specification and the operation, which implies that it supports this specification and the
updated RPL Target Option (see Section 6.1). updated RPL Target option (see Section 6.1).
Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the Section 4.1.3 of [RFC9008] updates [RFC6550] to indicate that the
definition of the Flags applies to Mode of Operation (MOP) values definition of the flags applies to MOP values from zero (0) to six
from zero (0) to six (6) only. For a MOP value of 7, the (6) only. For a MOP value of 7, the implementation MUST assume that
implementation MUST consider that the Root performs the proxy the root performs the proxy operation.
operation.
The RPL DODAG Configuration Option is typically placed in a DODAG The RPL DODAG Configuration option is typically placed in a DODAG
Information Object (DIO) message. The DIO message propagates down Information Object (DIO) message. The DIO message propagates down
the DODAG to form and then maintain its structure. The DODAG the DODAG to form and then maintain its structure. The DODAG
Configuration Option is copied unmodified from parents to children. Configuration option is copied unmodified from parents to children.
[RFC6550] states that "Nodes other than the DODAG Root MUST NOT [RFC6550] states that "Nodes other than the DODAG root MUST NOT
modify this information when propagating the DODAG Configuration modify this information when propagating the DODAG Configuration
option". Therefore, a legacy parent propagates the 'P' Flag as set option." Therefore, a legacy parent propagates the 'P' flag as set
by the Root, and when the 'P' Flag is set to 1, it is transparently by the root, and when the 'P' flag is set to 1, it is transparently
flooded to all the nodes in the DODAG. flooded to all the nodes in the DODAG.
6.3. 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. 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, see section The 6LoWPAN ND Status was defined for use in the EARO; see
4.1 of [RFC8505]. This specification adds a capability to allow the Section 4.1 of [RFC8505]. This specification adds the ability to
carriage of 6LoWPAN ND Status values in RPL DAO and DCO messages, allow the carriage of 6LoWPAN ND Status values in RPL DAO and DCO
embedded in the RPL Status field. messages, embedded in the RPL Status field.
To achieve this, the range of the ARO/EARO Status values is reduced To achieve this, the range of the ARO/EARO Status values is reduced
to 0-63, which updates the IANA registry created for [RFC6775]. This to 0-63, which updates the IANA registry created for [RFC6775]. This
reduction ensures that the values fit within a RPL Status as shown in reduction ensures that the values fit within a RPL Status as shown in
Figure 6. See Section 12.2, Section 12.5, and Section 12.6 for the Figure 6. See Sections 12.2, 12.5, and 12.6 for the respective IANA
respective IANA declarations. This ask is reasonable because the declarations. These updates are reasonable because the associated
associated registry relies on standards action for registration and registry relies on the Standards Action policy [RFC8126] for
only values up to 10 are currently allocated. registration and only values up to 10 are currently allocated.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|A|StatusValue| |U|A|StatusValue|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 6: RPL Status Format Figure 6: RPL Status Format
This specification updates the RPL Status with subfields as indicated This specification updates the RPL Status with the following
below: subfields:
E: 1-bit flag. set to 1 to indicate a rejection. When set to 0, a U: 1-bit flag. Set to 1 to indicate a rejection. When set to 0, a
Status value of 0 indicates Success/Unqualified acceptance and Status value of 0 indicates Success / Unqualified acceptance and
other values indicate "not an outright rejection" as per RFC 6550. other values indicate "Not an outright rejection" as per
RFC 6550.
A: 1-bit flag. Indicates the type of the RPL Status value. A: 1-bit flag. Indicates the type of the RPL Status value.
Status Value: 6-bit unsigned integer. Status Value: 6-bit unsigned integer.
If the 'A' flag is set to 1 this field transports a value defined If the 'A' flag is set to 1, this field transports a value
for the 6LoWPAN ND EARO Status. defined for the 6LoWPAN ND EARO Status.
When the 'A' flag is set to 0, this field transports a Status When the 'A' flag is set to 0, this field transports a Status
Value defined for RPL. value defined for RPL.
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 an
message, the RPL Root MUST copy the 6LoWPAN ND status code unchanged EDAC message, the RPL DODAG root MUST copy the 6LoWPAN ND status code
in the RPL Status Value and set the 'A' flag to 1. The RPL Root MUST unchanged in the RPL Status Value field and set the 'A' flag to 1.
set the 'E' flag to 1 for all rejection and unknown status codes. The RPL DODAG root MUST set the 'U' flag to 1 for all rejection and
The status codes in the 1-10 range [RFC8505] are all considered unknown status codes. The status codes in the 1-10 range [RFC8505]
rejections. 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 DODAG root
a RPL Status that has the 'A' flag set, the 6LR MUST copy the RPL with a RPL Status that has the 'A' flag set, the 6LR MUST copy the
Status value unchanged in the Status field of the EARO when RPL Status value unchanged in the Status field of the EARO when
generating an NA to the RUL. generating an NA to the RUL.
7. Enhancements to draft-ietf-roll-efficient-npdao 7. Enhancements to RFC 9009
[EFFICIENT-NPDAO] defines the DCO message for RPL Storing Mode only, [RFC9009] defines the DCO message for RPL Storing mode only, with a
with a link-local scope. All nodes in the RPL network are expected link-local scope. All nodes in the RPL network are expected to
to support the specification since the message is processed hop-by- support the specification, since the message is processed hop by hop
hop along the path that is being cleaned up. along the path that is being cleaned up.
This specification extends the use of the DCO message to the Non- This specification extends the use of the DCO message to the Non-
Storing MOP, whereby the DCO is sent end-to-end by the Root directly Storing MOP, whereby the DCO is sent end to end by the root directly
to the RAN that injected the DAO message for the considered target. to the RAN that injected the DAO message for the considered target.
In that case, intermediate nodes do not need to support In that case, intermediate nodes do not need to support [RFC9009];
[EFFICIENT-NPDAO]; they forward the DCO message as a plain IPv6 they forward the DCO message as a plain IPv6 packet between the root
packet between the Root and the RAN. and the RAN.
In the case of a RUL, the 6LR that serves the RUL acts as the RAN In the case of a RUL, the 6LR that serves the RUL acts as the RAN
that receives the Non-Storing DCO. This specification leverages the that receives the Non-Storing DCO. This specification leverages the
Non-Storing DCO between the Root and the 6LR that serves as Non-Storing DCO between the root and the 6LR that serves as the
attachment router for a RUL. A 6LR and a Root that support this attachment router for a RUL. A 6LR and a root that support this
specification MUST implement the Non-Storing DCO. specification MUST implement the Non-Storing DCO.
8. Enhancements to RFC6775 and RFC8505 8. Enhancements to RFCs 6775 and 8505
This document updates [RFC6775] and [RFC8505] to reduce the range of This document updates [RFC6775] and [RFC8505] to reduce the range of
the ND status codes down to 64 values. The two most significant the ARO/EARO Status values to 64 values. The two most significant
(leftmost) bits if the original ND status field are now reserved, (leftmost) bits of the original ND Status field are now reserved;
they MUST be set to zero by the sender and ignored by the receiver. they MUST be set to 0 by the sender and ignored by the receiver.
This document also updates the behavior of a 6LR acting as RPL router This document also updates the behavior of a 6LR acting as a RPL
and of a 6LN acting as RUL in the 6LoWPAN ND Address Registration as router and of a 6LN acting as a RUL in the 6LoWPAN ND Address
follows: Registration as follows:
* If the RPL Root advertises the capability to proxy the EDAR/EDAC * If the RPL DODAG root advertises the ability to proxy the EDAR/
exchange to the 6LBR, the 6LR refrains from sending the keep-alive EDAC exchange to the 6LBR, the 6LR refrains from sending the keep-
EDAR message. If it is separated from the 6LBR, the Root alive EDAR message. If it is separated from the 6LBR, the root
regenerates the EDAR message to the 6LBR periodically, upon a DAO regenerates the EDAR message to the 6LBR periodically, upon a DAO
message that signals the liveliness of the address. message that signals the liveliness of the address.
* The use of the R Flag is extended to the NA(EARO) to confirm * The use of the R flag is extended to the NA(EARO) to confirm
whether the route was installed. whether the route was installed.
9. Protocol Operations for Unicast Addresses 9. Protocol Operations for Unicast Addresses
The description below assumes that the Root sets the 'P' flag in the The description below assumes that the root sets the 'P' flag in the
DODAG Configuration Option and performs the EDAR proxy operation DODAG Configuration option and performs the EDAR proxy operation
presented in Section 4.3 . presented in Section 4.3.
If the 'P' flag is set to 0, the 6LR MUST generate the periodic EDAR If the 'P' flag is set to 0, 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.
Section 9.1 provides an overview of the route injection in RPL, Section 9.1 provides an overview of the route injection in RPL,
whereas Section 9.2 offers more details from the perspective of the whereas Section 9.2 offers more details from the perspective of the
different nodes involved in the flow. different nodes involved in the flow.
9.1. General Flow 9.1. General Flow
This specification eliminates the need to exchange keep-alive This specification eliminates the need to exchange keep-alive EDAR
Extended Duplicate Address messages, EDAR and EDAC, all the way from and EDAC messages all the way from a 6LN to the 6LBR across a RPL
a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange mesh. Instead, the EDAR/EDAC exchange with the 6LBR is proxied by
with the 6LBR is proxied by the RPL Root upon the DAO message that the RPL DODAG root upon the DAO message that refreshes the RPL
refreshes the RPL routing state. The first EDAR upon a new routing state. The first EDAR upon a new Address Registration cannot
Registration cannot be proxied, though, as it serves for the purpose be proxied, though, as it is generated for the purpose of DAD, which
of DAD, which must be verified before the address is injected in RPL. 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. Since RULs are advertised using Non-Storing Mode, the the RPL DODAG root. Since RULs are advertised using Non-Storing
DAO message flow and the keep alive EDAR/EDAC can be nested within mode, the DAO message flow and the keep-alive EDAR/EDAC can be nested
the Address (re)Registration flow. Figure 7 illustrates that, for within the Address (re)Registration flow. Figure 7 illustrates that,
the first Registration, both the DAD and the keep-alive EDAR/EDAC for the first Address Registration, both the DAD and the keep-alive
exchanges happen in the same sequence. EDAR/EDAC exchanges happen in the same sequence.
6LN/RUL 6LR <6LR*> Root 6LBR 6LN/RUL 6LR <6LR*> Root 6LBR
|<---Using ND--->|<--Using RPL->|<-----Using ND---->| |<---Using ND--->|<--Using RPL->|<-----Using ND---->|
| |<-----------Using ND------------->| | |<-----------Using ND------------->|
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | EDAR | | | EDAR |
| |--------------------------------->| | |--------------------------------->|
| | | | | |
skipping to change at page 22, line 4 skipping to change at line 991
| |<---------------------------------| | |<---------------------------------|
| | | | | |
| | DAO(X=0) | | | | DAO(X=0) | |
| |------------->| | | |------------->| |
| | | | | |
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
Figure 7: First RUL Registration Flow Figure 7: First RUL Registration Flow
This flow requires that the lifetimes and sequence counters in This flow requires that the lifetimes and sequence counters in
6LoWPAN ND and RPL are aligned. 6LoWPAN ND and RPL be aligned.
To achieve this, the Path Sequence and the Path Lifetime in the DAO To achieve this, the Path Sequence and the Path Lifetime in the DAO
message are taken from the Transaction ID and the Address message are taken from the Transaction ID and the Address
Registration lifetime in the NS(EARO) message from the 6LN. Registration lifetime in the NS(EARO) message from the 6LN.
On the first Address Registration, illustrated in Figure 7 for RPL On the first Address Registration, illustrated in Figure 7 for RPL
Non-Storing Mode, the Extended Duplicate Address exchange takes place Non-Storing mode, the EDAR/EDAC exchange takes place as prescribed by
as prescribed by [RFC8505]. If the exchange fails, the 6LR returns [RFC8505]. If the exchange fails, the 6LR returns an NA message with
an NA message with a non-zero status to the 6LN, the NCE is not a non-zero status to the 6LN, the NCE is not created, and the address
created, and the address is not injected in RPL. Otherwise, the 6LR is not injected in RPL. Otherwise, the 6LR creates an NCE and
creates an NCE and injects the Registered Address in the RPL routing injects the Registered Address in the RPL routing using a DAO/DAO-ACK
using a DAO/DAO-ACK exchange with the RPL DODAG Root. exchange with the RPL DODAG root.
An Address Registration refresh is performed by the 6LN to keep the An Address Registration refresh is performed by the 6LN to keep the
NCE in the 6LR alive before the lifetime expires. Upon the refresh NCE in the 6LR alive before the lifetime expires. Upon the refresh
of a registration, the 6LR reinjects the corresponding route in RPL of a registration, the 6LR reinjects the corresponding route in RPL
before it expires, as illustrated in Figure 8. before it expires, as illustrated in Figure 8.
6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR 6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | | |--------------->| | |
skipping to change at page 22, line 43 skipping to change at line 1031
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 8: 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 DODAG root to refresh the state in the
using an EDAC message. In case of an error in the proxied EDAR flow, 6LBR, using an EDAC message. In the case of an error in the proxied
the error is returned in the DAO-ACK using a RPL Status with the 'A' EDAR flow, the error is returned in the DAO-ACK using a RPL Status
flag set to 1 that imbeds a 6LoWPAN Status value as discussed in with the 'A' flag set to 1, which embeds a 6LoWPAN Status value as
Section 6.3. discussed in 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 Non-Storing DCO, but the non-zero status in the DCO asynchronous Non-Storing DCO, but the non-zero status in the DCO
supersedes a positive Status in the DAO-ACK regardless of the order supersedes a positive status in the DAO-ACK, regardless of the order
in which they are received. Upon the DAO-ACK - or the DCO if one in which they are received. Upon the DAO-ACK -- or the DCO, if one
arrives first - the 6LR responds to the RUL with an NA(EARO). arrives first -- the 6LR responds to the RUL with an NA(EARO).
An issue may be detected later, e.g., the address moves to a An issue may be detected later, e.g., the address moves to a
different DODAG with the 6LBR attached to a different 6LoWPAN different DODAG with the 6LBR attached to a different 6LoWPAN
Backbone router (6BBR), see Figure 5 in section 3.3 of [RFC8929]. Backbone Router (6BBR); see Figure 5 in Section 3.3 of [RFC8929].
The 6BBR may send a negative ND status, e.g., in an asynchronous The 6BBR may send a negative ND Status, e.g., in an asynchronous
NA(EARO) to the 6LBR. NA(EARO) to the 6LBR.
[RFC8929] expects that the 6LBR is collocated with the RPL Root, but [RFC8929] expects that the 6LBR is co-located with the RPL DODAG
if not, the 6LBR MUST forward the status code to the originator of root, but if not, the 6LBR MUST forward the status code to the
the EDAR, either the 6LR or the RPL Root that proxies for it. The ND originator of the EDAR -- either the 6LR or the RPL DODAG root that
status code is mapped in a RPL Status value by the RPL Root, and then proxies for it. The ND status code is mapped in a RPL Status value
back by the 6LR. Note that a legacy RAN that receives a Non-Storing by the RPL DODAG root, and then back to an ND Status by the 6LR to
DCO that it does not support will ignore it silently, as specified in the 6LN. Note that a legacy RAN that receives a Non-Storing DCO that
section 6 of [RFC6550]. The result is that it may ignore for a while it does not support will ignore it silently, as specified in
that it is no more reachable. The situation will be cleared upon the Section 6 of [RFC6550]. The result is that it will remain unaware
next Non-Storing DAO exchange if the error is returned in a DAO-ACK. that it is no longer reachable until its next RPL exchange happens.
This situation will be cleared upon the next Non-Storing DAO exchange
if the error is returned in a DAO-ACK.
Figure 9 illustrates this in the case where the 6LBR and the Root are Figure 9 illustrates this in the case where the 6LBR and the root are
not collocated, and the Root proxies the EDAR/EDAC flow. not co-located, and the root proxies the EDAR/EDAC flow.
6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR <-ND-> 6BBR 6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR <-ND-> 6BBR
| | | | | | | | | |
| | | | NA(EARO) | | | | | NA(EARO) |
| | | |<------------| | | | |<------------|
| | | EDAC | | | | | EDAC | |
| | |<-------------| | | | |<-------------| |
| | DCO | | | | | DCO | | |
| |<------------| | | | |<------------| | |
| NA(EARO) | | | | | NA(EARO) | | | |
|<-------------| | | | |<-------------| | | |
| | | | | | | | | |
Figure 9: Asynchronous Issue Figure 9: Asynchronous Issue
If the Root does not proxy, then the EDAC with a non-zero status If the root does not proxy, then the EDAC with a non-zero status
reaches the 6LR directly. In that case, the 6LR MUST clean up the reaches the 6LR directly. In that case, the 6LR MUST clean up the
route using a DAO with a Lifetime of zero, and it MUST propagate the route using a DAO with a Lifetime of 0, and it MUST propagate the
status back to the RUL in a NA(EARO) with the R Flag set to 0. status back to the RUL in an NA(EARO) with the R flag set to 0.
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 transport 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 a
proxy, as illustrated in Figure 8. proxy, as illustrated in Figure 8.
Any combination of the logical functions of 6LR, Root, and 6LBR might All or any combination of the 6LR, the root, and the 6LBR might be
be collapsed in a single node. collapsed in a single node.
9.2. Detailed Operation 9.2. Detailed Operation
The following section specify respectively the behaviour of the 6LN The following sections specify the behavior of (1) the 6LN acting as
Acting as RUL, the 6LR Acting as Border router and serving the 6LN, a RUL, (2) the 6LR acting as a border router and serving the 6LN,
the RPL Root and the 6LBR in the control flows that enable RPL (3) the RPL DODAG root, and (4) the 6LBR in the control flows that
routing back to the RUL. enable RPL routing back to the RUL, respectively.
9.2.1. Perspective of the 6LN Acting as RUL 9.2.1. Perspective of the 6LN Acting as a RUL
This specification builds on the operation of a 6LoWPAN ND-compliant This specification builds on the operation of a 6LoWPAN ND-compliant
6LN/RUL, which is expected to operate as follows: 6LN/RUL, which is expected to operate as follows:
1. The 6LN selects a 6LR that provides reachability services for a 1. The 6LN selects a 6LR that provides reachability services for a
RUL. This is signaled by a 6CIO in the RA messages with the L, P RUL. This is signaled by a 6CIO in the RA messages with the L,
and E flags set to 1 as prescribed by [RFC8505]. P, and E flags set to 1 as prescribed by [RFC8505].
2. The 6LN obtains an IPv6 global address, either using Stateless 2. The 6LN obtains an IPv6 global address, via either (1) 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 [RFC8415]. (2) some other means, such as DHCPv6 [RFC8415].
3. Once it has formed an address, the 6LN registers its address and 3. Once it has formed an address, the 6LN registers its address and
refreshes its registration periodically, early enough within the refreshes its registration periodically, early enough within the
Lifetime of the previous Address Registration, as prescribed by lifetime of the previous Address Registration, as prescribed by
[RFC6775], to refresh the NCE before the lifetime indicated in [RFC6775], to refresh the NCE before the lifetime indicated in
the EARO expires. It sets the T Flag to 1 as prescribed in the EARO expires. It sets the T flag to 1 as prescribed in
[RFC8505]. The TID is incremented each time and wraps in a [RFC8505]. The TID is incremented each time and wraps in a
lollipop fashion (see section 5.2.1 of [RFC8505], which is fully lollipop fashion (see Section 5.2.1 of [RFC8505], which is fully
compatible with section 7.2 of [RFC6550]). compatible with Section 7.2 of [RFC6550]).
4. As stated in section 5.2 of [RFC8505], the 6LN can register to 4. As stated in Section 5.2 of [RFC8505], the 6LN can register with
more than one 6LR at the same time. In that case, it uses the more than one 6LR at the same time. In that case, all the fields
same EARO for all of the parallel Address Registrations, with the in the EARO are set to the same value for all of the parallel
exception of the Registration Lifetime field and the setting of Address Registrations, with the exception of the Registration
the R flag that may differ. The 6LN may cancel a subset of its Lifetime field and the R flag, which may be set to different
registrations, or transfer a registration from one or more old values. The 6LN may cancel a subset of its registrations or may
6LR(s) to one or more new 6LR(s). To do so, the 6LN sends a transfer a registration from one or more old 6LRs to one or more
series of NS(EARO) messages, all with the same TID, with a zero new 6LRs. To do so, the 6LN sends a series of NS(EARO) messages,
Registration Lifetime to the old 6LR(s) and with a non-zero all with the same TID, with a zero Registration Lifetime to the
Registration Lifetime to the new 6LR(s). In that process, the old 6LR(s) and with a non-zero Registration Lifetime to the new
6LN SHOULD send the NS(EARO) with a non-zero Registration 6LR(s). In that process, the 6LN SHOULD send the NS(EARO) with a
Lifetime and ensure that at least one succeeds before it sends an non-zero Registration Lifetime and ensure that at least one
NS(EARO) that terminates another registration. This avoids the succeeds before it sends an NS(EARO) that terminates another
churn related to transient route invalidation in the RPL network registration. This avoids the churn related to transient route
above the common parent of the involved 6LRs. invalidation in the RPL network above the common parent of the
involved 6LRs.
5. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets 5. Following Section 5.1 of [RFC8505], a 6LN acting as a RUL sets
the R Flag in the EARO of its registration(s) for which it the R flag in the EARO of its registration(s) for which it
requires routing services. If the R Flag is not echoed in the requires routing services. If the R flag is not echoed in the
NA, the RUL MUST consider that establishing the routing services NA, the RUL MUST assume that establishing the routing services
via this 6LR failed and it SHOULD attempt to use another 6LR. via this 6LR failed, and it SHOULD attempt to use another 6LR.
The RUL SHOULD ensure that one registration succeeds before The RUL SHOULD ensure that one registration succeeds before
setting the R Flag to 0. In case of a conflict with the setting the R flag to 0. In the case of a conflict with the
preceding rule on lifetime, the rule on lifetime has precedence. preceding rule regarding the lifetime, the rule regarding the
lifetime has precedence.
6. The 6LN may use any of the 6LRs to which it registered as the 6. The 6LN may use any of the 6LRs to which it registered as the
default gateway. Using a 6LR to which the 6LN is not registered default gateway. Using a 6LR to which the 6LN is not registered
may result in packets dropped at the 6LR by a Source Address may result in packets dropped at the 6LR by a Source Address
Validation function (SAVI) [RFC7039] so it is not recommended. Validation Improvement (SAVI) function [RFC7039] and thus is not
recommended.
Even without support for RPL, the RUL may be configured with an Even without support for RPL, the RUL may be configured with an
opaque value to be provided to the routing protocol. If the RUL has opaque value to be provided to the routing protocol. If the RUL has
knowledge of the RPL Instance the packet should be injected into, knowledge of the RPL Instance into which the packet should be
then it SHOULD set the Opaque field in the EARO to the RPLInstanceID, injected, then it SHOULD set the Opaque field in the EARO to the
otherwise it MUST leave the Opaque field as zero. RPLInstanceID; otherwise, it MUST leave the Opaque field as 0.
Regardless of the setting of the Opaque field, the 6LN MUST set the Regardless of the setting of the Opaque field, the 6LN MUST set the
"I" field to zero to signal "topological information to be passed to "I" field to 0 to signal "topological information to be passed to a
a routing process", as specified in section 5.1 of [RFC8505]. 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 minimal awareness of but it may do so. For instance, if the RUL has minimal awareness of
the RPL Instance then it can build an RPI. A RUL that places an RPI the RPL Instance, then it can build an RPI. A RUL that places an RPI
in a data packet SHOULD indicate the RPLInstanceID of the RPL in a data packet SHOULD indicate the RPLInstanceID of the RPL
Instance where the packet should be forwarded. It is up to the 6LR Instance where the packet should be forwarded. It is up to the 6LR
(e.g., by policy) to use the RPLInstanceID information provided by (e.g., by policy) to use the RPLInstanceID information provided by
the RUL or rewrite it to the selected RPLInstanceID for forwarding the RUL or rewrite it to the selected RPLInstanceID for forwarding
inside the RPL domain. All the flags and the Rank field are set to 0 inside the RPL domain. All the flags and the SenderRank field are
as specified by section 11.2 of [RFC6550]. set to 0 as specified by Section 11.2 of [RFC6550].
9.2.2. Perspective of the 6LR Acting as Border router 9.2.2. Perspective of the 6LR Acting as a Border Router
A 6LR that provides reachability services for a RUL in a RPL network A 6LR that provides reachability services for a RUL in a RPL network
as specified in this document MUST include a 6CIO in its RA messages as specified in this document MUST include a 6CIO in its RA messages
and set the L, P and E flags to 1 as prescribed by [RFC8505]. and set the L, P, and E flags to 1 as prescribed by [RFC8505].
As prescribed by [RFC8505], the 6LR generates an EDAR message upon As prescribed by [RFC8505], the 6LR generates an EDAR message upon
reception of a valid NS(EARO) message for the registration of a new reception of a valid NS(EARO) message for the registration of a new
IPv6 address by a 6LN. If the initial EDAR/EDAC exchange succeeds, IPv6 address by a 6LN. If the initial EDAR/EDAC exchange succeeds,
then the 6LR installs an NCE for the Registration Lifetime. then the 6LR installs an NCE for the Registration Lifetime.
If the R Flag is set to 1 in the NS(EARO), the 6LR SHOULD inject the If the R flag is set to 1 in the NS(EARO), the 6LR SHOULD inject the
host route in RPL, unless this is barred for other reasons, such as host 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- the saturation of the RPL parents. The 6LR MUST use RPL Non-Storing
Storing Mode signaling and the updated Target Option (see mode signaling and the updated Target option (see Section 6.1). To
Section 6.1). The 6LR SHOULD refrain from setting the 'X' flag to avoid a redundant EDAR/EDAC flow to the 6LBR, the 6LR SHOULD refrain
avoid a redundant EDAR/EDAC flow to the 6LBR. The 6LR MUST request a from setting the 'X' flag. The 6LR MUST request a DAO-ACK by setting
DAO-ACK by setting the 'K' flag in the DAO message. Success the 'K' flag in the DAO message. Successfully injecting the route to
injecting the route to the RUL's address is indicated by the 'E' flag the RUL's address will be indicated via the 'U' flag set to 0 in the
set to 0 in the RPL status of the DAO-ACK message. RPL Status of the DAO-ACK message.
For the registration refreshes, if the RPL Root sets the 'P' flag in For the registration refreshes, if the RPL DODAG root sets the 'P'
the DODAG Configuration Option to 1, then the 6LR MUST refrain from flag in the DODAG Configuration option to 1, then the 6LR MUST
sending the keep-alive EDAR; instead, it MUST set the 'X' flag to 1 refrain from sending the keep-alive EDAR; instead, it MUST set the
in the Target Option of the DAO messages, to request that the Root 'X' flag to 1 in the Target option of the DAO messages, to request
proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see that the root proxy the keep-alive EDAR/EDAC exchange with the 6LBR
Section 6); if the 'P' flag is set to 0 then the 6LR MUST set the 'X' (see Section 6); if the 'P' flag is set to 0, then the 6LR MUST set
flag to 0 and handle the EDAR/EDAC flow itself. the 'X' flag to 0 and handle the EDAR/EDAC flow itself.
The Opaque field in the EARO provides a means to signal which RPL The Opaque field in the EARO provides a means to signal which RPL
Instance is to be used for the DAO advertisements and the forwarding Instance is to be used for the DAO advertisements and the forwarding
of packets sourced at the Registered Address when there is no RPI in of packets sourced at the Registered Address when there is no RPI in
the packet. the packet.
As described in [RFC8505], if the "I" field is zero, then the Opaque As described in [RFC8505], if the "I" field is 0, then the Opaque
field is expected to carry the RPLInstanceID suggested by the 6LN; field is expected to carry the RPLInstanceID suggested by the 6LN;
otherwise, there is no suggested Instance. If the 6LR participates otherwise, there is no suggested RPL Instance. If the 6LR
in the suggested RPL Instance, then the 6LR MUST use that RPL participates in the suggested RPL Instance, then the 6LR MUST use
Instance for the Registered Address. that RPL Instance for the Registered Address.
If there is no suggested RPL Instance or else if the 6LR does not If there is no suggested RPL Instance or if the 6LR does not
participate to the suggested Instance, it is expected that the participate in the suggested RPL Instance, it is expected that the
packets coming from the 6LN "can unambiguously be associated to at packets coming from the 6LN "can unambiguously be associated to at
least one RPL Instance" [RFC6550] by the 6LR, e.g., using a policy least one RPL Instance" [RFC6550] by the 6LR, e.g., using a policy
that maps the 6-tuple into an Instance. that maps the 6-tuple to a RPL Instance.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is signaled as the Target Prefix in the 1. The Registered Address is signaled as the Target Prefix in the
updated Target Option in the DAO message; the Prefix Length is updated Target option in the DAO message; the Prefix Length is
set to 128 but the 'F' flag is set to 0 since the advertiser is set to 128 but the 'F' flag is set to 0, since the advertiser is
not the RUL. The ROVR field is copied unchanged from the EARO not the RUL. The ROVR field is copied unchanged from the EARO
(see Section 6.1). (see Section 6.1).
2. The 6LR indicates one of its global or unique-local IPv6 unicast 2. The 6LR indicates one of its global or unique-local IPv6 unicast
addresses as the Parent Address in the TIO associated with the addresses as the Parent Address in the TIO associated with the
Target Option Target option.
3. The 6LR sets the External 'E' flag in the TIO to indicate that it 3. The 6LR sets the External ('E') flag in the TIO to indicate that
is redistributing an external target into the RPL network it is redistributing an external target into the RPL network.
4. The Path Lifetime in the TIO is computed from the Registration 4. The Path Lifetime in the TIO is computed from the Registration
Lifetime in the EARO. This operation converts seconds to the Lifetime in the EARO. This operation converts seconds to the
Lifetime Units used in the RPL operation. This creates the Lifetime Units used in the RPL operation. This creates the
deployment constraint that the Lifetime Unit is reasonably deployment constraint that the Lifetime Unit is reasonably
compatible with the expression of the Registration Lifetime; compatible with the expression of the Registration Lifetime;
e.g., a Lifetime Unit of 0x4000 maps the most significant byte of e.g., a Lifetime Unit of 0x4000 maps the most significant byte of
the Registration Lifetime to the Path Lifetime. the Registration Lifetime to the Path Lifetime.
In that operation, the Path Lifetime must be set to ensure that In that operation, the Path Lifetime must be set to ensure that
the path has a longer lifetime than the registration and covers the path has a longer lifetime than the registration and also
in addition the round trip time to the Root. covers the round-trip time to the root.
Note that if the Registration Lifetime is 0, then the Path Note that if the Registration Lifetime is 0, then the Path
Lifetime is also 0 and the DAO message becomes a No-Path DAO, Lifetime is also 0 and the DAO message becomes a No-Path DAO,
which cleans up the routes down to the RUL's address; this also which cleans up the routes down to the RUL's address; this also
causes the Root as a proxy to send an EDAR message to the 6LBR causes the root as a proxy to send an EDAR message to the 6LBR
with a Lifetime of 0. with a Lifetime of 0.
5. the Path Sequence in the TIO is set to the TID value found in the 5. The Path Sequence in the TIO is set to the TID value found in the
EARO option. EARO.
Upon receiving or timing out the DAO-ACK after an implementation- Upon receiving or timing out the DAO-ACK after an implementation-
specific number of retries, the 6LR MUST send the corresponding specific number of retries, the 6LR MUST send the corresponding
NA(EARO) to the RUL. Upon receiving an asynchronous DCO message, it NA(EARO) to the RUL. Upon receiving an asynchronous DCO message, it
MUST send an asynchronous NA(EARO) to the RUL immediately, but still MUST send an asynchronous NA(EARO) to the RUL immediately but still
be capable of processing the DAO-ACK if one is pending. be capable of processing the DAO-ACK if one is pending.
The 6LR MUST set the R Flag to 1 in the NA(EARO) back if and only if The 6LR MUST set the R flag to 1 in the NA(EARO) that it sends back
the 'E' flag in the RPL Status is set to 0, indicating that the 6LR to the 6LN if and only if the 'U' flag in the RPL Status is set to 0,
injected the Registered Address in the RPL routing successfully and indicating that the 6LR injected the Registered Address in the RPL
that the EDAR proxy operation succeeded. routing successfully and that the EDAR proxy operation succeeded.
If the 'A' flag in the RPL Status is set to 1, the embedded Status If the 'A' flag in the RPL Status is set to 1, the embedded Status
value is passed back to the RUL in the EARO Status. If the 'E' flag value is passed back to the RUL in the EARO Status. If the 'U' flag
is also set to 1, the registration failed for 6LoWPAN-ND-related is also set to 1, the registration failed for 6LoWPAN-ND-related
reasons, and the NCE is removed. reasons, and the NCE is removed.
An error injecting the route causes the 'E' flag to be set to 1. If An error injecting the route causes the 'U' flag to be set to 1. If
the error is not related to ND, the 'A' flag is set to 0. In that the error is not related to ND, the 'A' flag is set to 0. In that
case, the registration succeeds, but the RPL route is not installed. case, the registration succeeds, but the RPL route is not installed.
So the NA(EARO) is returned with a status indicating success but the So, the NA(EARO) is returned with a status indicating success but the
R Flag set to 0, which means that the 6LN obtained a binding but no R flag set to 0, which means that the 6LN obtained a binding but no
route. route.
If the 'A' flag is set to 0 in the RPL Status of the DAO-ACK, then If the 'A' flag is set to 0 in the RPL Status of the DAO-ACK, then
the 6LoWPAN ND operation succeeded, and an EARO Status of 0 (Success) the 6LoWPAN ND operation succeeded, and an EARO Status of 0 (Success)
MUST be returned to the 6LN. The EARO Status of 0 MUST also be used MUST be returned to the 6LN. The EARO Status of 0 MUST also be used
if the 6LR did not attempt to inject the route but could create the if the 6LR did not attempt to inject the route but could create the
binding after a successful EDAR/EDAC exchange or refresh it. binding after a successful EDAR/EDAC exchange or refresh it.
If the 'E' flag is set to 1 in the RPL Status of the DAO-ACK, then If the 'U' flag is set to 1 in the RPL Status of the DAO-ACK, then
the route was not installed and the R flag MUST be set to 0 in the the route was not installed, and the R flag MUST be set to 0 in the
NA(EARO). The R flag MUST be set to 0 if the 6LR did not attempt to NA(EARO). The R flag MUST be set to 0 if the 6LR did not attempt to
inject the route. inject the route.
In a network where Address Protected Neighbor Discovery (AP-ND) is In a network where Address-Protected Neighbor Discovery (AP-ND) is
enabled, in case of a DAO-ACK or a DCO transporting an EARO Status enabled, in the case of a DAO-ACK or a DCO transporting an EARO
value of 5 (Validation Requested), the 6LR MUST challenge the 6LN for Status value of 5 (Validation Requested), the 6LR MUST challenge the
ownership of the address, as described in section 6.1 of [RFC8928], 6LN for ownership of the address, as described in Section 6.1 of
before the Registration is complete. This flow, illustrated in [RFC8928], before the registration is complete. This flow,
Figure 10, ensures that the address is validated before it is illustrated in Figure 10, ensures that the address is validated
injected in the RPL routing. before it is injected in the RPL routing.
If the challenge succeeds, then the operations continue as normal.
In particular, a DAO message is generated upon the NS(EARO) that
proves the ownership of the address. If the challenge failed, the
6LR rejects the registration as prescribed by AP-ND and may take
actions to protect itself against DoS attacks by a rogue 6LN, see
Section 11.
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
|<--------------- RA ---------------------| | | |<--------------- RA ---------------------| | |
| | | | | | | |
|------ NS EARO (ROVR=Crypto-ID) -------->| | | |------ NS(EARO) (ROVR=Crypto-ID) ------->| | |
| | | | | | | |
|<- NA EARO(status=Validation Requested) -| | | |<-NA(EARO) (Status=Validation Requested)-| | |
| | | | | | | |
|----- NS EARO and Proof-of-ownership -->| | |---- NS(EARO) and proof of ownership --->| | |
| | | | | | | |
| <validate the Proof> | | | <validate the proof> | |
| | | | | |
|<----------- NA EARO (status=10)---<if failed> | | |<------- NA(EARO) (Status=10) -----<if failed> | |
| | | | | |
| <else> | | | <else> | |
| | | | | | | |
| |--------- EDAR ------->| | |--------- EDAR ------->|
| | | | | |
| |<-------- EDAC --------| | |<-------- EDAC --------|
| | | | | |
| | | | | | | |
| |-DAO(X=0)->| | | |-DAO(X=0)->| |
| | | | | | | |
| |<- DAO-ACK-| | | |<- DAO-ACK-| |
| | | | | | | |
|<----------- NA EARO (status=0)----------| | | |<---------- NA(EARO) (Status=0) ---------| | |
| | | | | | | |
... ...
| | | | | | | |
|------ NS EARO (ROVR=Crypto-ID) -------->| | | |------ NS(EARO) (ROVR=Crypto-ID) ------->| | |
| |-DAO(X=1)->| | | |-DAO(X=1)->| |
| | |-- EDAR -->| | | |-- EDAR -->|
| | | | | | | |
| | |<-- EDAC --| | | |<-- EDAC --|
| |<- DAO-ACK-| | | |<- DAO-ACK-| |
|<----------- NA EARO (status=0)----------| | | |<---------- NA(EARO) (Status=0) ---------| | |
| | | | | | | |
... ...
Figure 10: Address Protection Figure 10: Address Protection
The 6LR may at any time send a unicast asynchronous NA(EARO) with the If the challenge succeeded, then the operations continue as normal.
R Flag set to 0 to signal that it stops providing routing services, In particular, a DAO message is generated upon the NS(EARO) that
and/or with the EARO Status 2 "Neighbor Cache full" to signal that it proves the ownership of the address. If the challenge failed, the
removes the NCE. It may also send a final RA, unicast or multicast, 6LR rejects the registration as prescribed by AP-ND and may take
with a router Lifetime field of zero, to signal that it is ceasing to actions to protect itself against Denial-Of-Service (DoS) attacks by
serve as router, as specified in section 6.2.5 of [RFC4861]. This a rogue 6LN; see Section 11.
may happen upon a DCO or a DAO-ACK message indicating the path is
already removed; else the 6LR MUST remove the host route to the 6LN
using a DAO message with a Path Lifetime of zero.
A valid NS(EARO) message with the R Flag set to 0 and a Registration The 6LR may, at any time, send a unicast asynchronous NA(EARO) with
the R flag set to 0 to signal that it has stopped providing routing
services, and/or with an EARO Status of 2 (Neighbor Cache Full) to
signal that it removed the NCE. It may also send a final RA --
unicast or multicast -- with a router Lifetime field of 0, to signal
that it will cease to serve as the router, as specified in
Section 6.2.5 of [RFC4861]. This may happen upon a DCO or a DAO-ACK
message indicating that the path is already removed; otherwise, the
6LR MUST remove the host route to the 6LN using a DAO message with a
Path Lifetime of 0.
A valid NS(EARO) message with the R flag set to 0 and a Registration
Lifetime that is not zero signals that the 6LN wishes to maintain the Lifetime that is not zero signals that the 6LN wishes to maintain the
binding but does not require the routing services from the 6LR (any binding but does not require (i.e., no longer requires) the routing
more). Upon this message, if, due to previous NS(EARO) with the R services from the 6LR. Upon this message, if, due to a previous
Flag set to 1, the 6LR was injecting the host route to the Registered NS(EARO) with the R flag set to 1 the 6LR was injecting the host
Address in RPL using DAO messages, then the 6LR MUST invalidate the route to the Registered Address in RPL using DAO messages, then the
host route in RPL using a DAO with a Path Lifetime of zero. It is up 6LR MUST invalidate the host route in RPL using a DAO with a Path
to the Registering 6LN to maintain the corresponding route from then Lifetime of 0. It is up to the registering 6LN to maintain the
on, either keeping it active via a different 6LR or by acting as a corresponding route from then on, by either (1) keeping it active via
RAN and managing its own reachability. a different 6LR or (2) acting as a RAN and managing its own
reachability.
When forwarding a packet from the RUL into the RPL domain, if the When forwarding a packet from the RUL into the RPL domain, if the
packet does not have an RPI then the 6LR MUST encapsulate the packet packet does not have an RPI, the 6LR MUST encapsulate the packet to
to the Root, and add an RPI. If there is an RPI in the packet, the the root and add an RPI. If there is an RPI in the packet, the 6LR
6LR MUST rewrite the RPI but it does not need to encapsulate. MUST rewrite the RPI, but it does not need to encapsulate.
9.2.3. Perspective of the RPL Root 9.2.3. Perspective of the RPL DODAG Root
A RPL Root MUST set the 'P' flag to 1 in the RPL DODAG Configuration A RPL DODAG root MUST set the 'P' flag to 1 in the RPL DODAG
Option of the DIO messages that it generates (see Section 6) to Configuration option of the DIO messages that it generates (see
signal that it proxies the EDAR/EDAC exchange and supports the Section 6) to signal that it proxies the EDAR/EDAC exchange and
Updated RPL Target option. supports the updated RPL Target option.
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 6.1) with the 'X' flag set to 1, the Root MUST notify (see Section 6.1) with the 'X' flag set to 1, the root MUST notify
the 6LBR by using a proxied EDAR/EDAC exchange; if the RPL Root and the 6LBR by using a proxied EDAR/EDAC exchange; if the RPL DODAG root
the 6LBR are integrated, an internal API can be used instead. and the 6LBR are integrated, an internal API can be used instead.
The EDAR message MUST be constructed as follows: The EDAR message MUST be constructed as follows:
1. The Target IPv6 address from the RPL Target Option is placed in 1. The target IPv6 address from the RPL Target option is placed in
the Registered Address field of the EDAR message; the Registered Address field of the EDAR message;
2. the Registration Lifetime is adapted from the Path Lifetime in 2. The Registration Lifetime is adapted from the Path Lifetime in
the TIO by converting the Lifetime Units used in RPL into units the TIO by converting the Lifetime Units used in RPL into units
of 60 seconds used in the 6LoWPAN ND messages; of 60 seconds used in the 6LoWPAN ND messages;
3. The TID value is set to the Path Sequence in the TIO and 3. The TID value is set to the Path Sequence in the TIO and
indicated with an ICMP code of 1 in the EDAR message; indicated with an ICMP code of 1 in the EDAR message;
4. The ROVR in the RPL Target Option is copied as is in the EDAR and 4. The ROVR in the RPL Target option is copied as is in the EDAR,
the ICMP Code Suffix is set to the appropriate value as shown in and the ICMP Code Suffix is set to the appropriate value as shown
Table 4 of [RFC8505] depending on the size of the ROVR field. in Table 4 of [RFC8505], depending on the size of the ROVR field.
Upon receiving an EDAC message from the 6LBR, if a DAO is pending, Upon receiving an EDAC message from the 6LBR, if a DAO is pending,
then the Root MUST send a DAO-ACK back to the 6LR. Otherwise, if the then the root MUST send a DAO-ACK back to the 6LR. Otherwise, if the
Status in the EDAC message is not "Success", then it MUST send an status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. asynchronous DCO to the 6LR.
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 to 1. the 'A' flag set to 1.
The proxied EDAR/EDAC exchange MUST be protected with a timer of an The proxied EDAR/EDAC exchange MUST be protected with a timer whose
appropriate duration and a number of retries, that are appropriate duration and number of retries (1) are implementation
implementation-dependent, and SHOULD be configurable since the Root dependent and (2) SHOULD be configurable, since the root and the 6LBR
and the 6LBR are typically nodes with a higher capacity and are typically nodes with a higher capacity and manageability than
manageability than 6LRs. Upon timing out, the Root MUST send an 6LRs. Upon timing out, the root MUST send an error back to the 6LR
error back to the 6LR as above, either using a DAO-ACK or a DCO, as as above, using either a DAO-ACK or a DCO, as appropriate, with the
appropriate, with the 'A' and 'E' flags set to 1 in the RPL status, 'A' and 'U' flags set to 1 in the RPL Status, and a RPL Status value
and a RPL Status value of of "6LBR Registry Saturated" [RFC8505]. of "6LBR Registry Saturated" [RFC8505].
9.2.4. 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 DODAG root is not the new attachment
of the RUL, so it is not impacted by this specification. 6LR 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 behaves as prescribed by
[RFC8505] and returns an EDAC message to the sender. [RFC8505] and returns an EDAC message to the sender.
10. Protocol Operations for Multicast Addresses 10. Protocol Operations for Multicast Addresses
Section 12 of [RFC6550] details the RPL support for multicast flows. Section 12 of [RFC6550] details RPL support for multicast flows.
This support is activated by the MOP of 3 ("Storing Mode of Operation This support is activated by setting the MOP value to 3 ("Storing
with multicast support") in the DIO messages that form the DODAG. Mode of Operation with multicast support") in the DIO messages that
This section also applies if and only if the MOP of the RPLInstance form the DODAG. This section also applies if and only if the MOP of
is 3. the RPL Instance is 3.
The RPL support of multicast is not source-specific and only operates RPL support for multicast is not source specific and only operates as
as an extension to the Storing Mode of Operation for unicast packets. an extension to the Storing mode of operation for unicast packets.
Note that it is the RPL model that the multicast packet is passed as Note that it is the RPL model that the multicast packet is copied and
a Layer-2 unicast to each of the interested children. This remains transmitted as a Layer 2 unicast to each of the interested children.
true when forwarding between the 6LR and the listener 6LN. This remains true when forwarding between the 6LR and the listener
6LN.
"Multicast Listener Discovery Version 2 (MLDv2) for IPv6" [RFC3810] "Multicast Listener Discovery Version 2 (MLDv2) for IPv6" [RFC3810]
provides an interface for a listener to register to multicast flows. provides an interface for a listener to register with multicast
In the MLD model, the router is a "querier", and the host is a flows. In the MLD model, the router is a "querier", and the host is
multicast listener that registers to the querier to obtain copies of a multicast listener that registers with the querier to obtain copies
the particular flows it is interested in. of the particular flows it is interested in.
The equivalent of the first Address Registration happens as The equivalent of the first Address Registration happens as
illustrated in Figure 11. The 6LN, as an MLD listener, sends an illustrated in Figure 11. The 6LN, as an MLD listener, sends an
unsolicited Report to the 6LR. This enables it to start receiving unsolicited Report to the 6LR. This enables it to start receiving
the flow immediately, and causes the 6LR to inject the multicast the flow immediately and causes the 6LR to inject the multicast route
route in RPL. in RPL.
This specification does not change MLD but will operate more
efficiently if the asynchronous messages for unsolicited Report and
Done are sent by the 6LN as Layer-2 unicast to the 6LR, in particular
on wireless.
The 6LR acts as a generic MLD querier and generates a DAO with the
Multicast Address as the Target Prefix as described in section 12 of
[RFC6550]. As for the Unicast host routes, the Path Lifetime
associated to the Target is mapped from the Query Interval, and set
to be larger to account for variable propagation delays to the Root.
The Root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the
RPL domain.
Upon a DAO with a Target option for a multicast address, the RPL Root
checks if it is already registered as a listener for that address,
and if not, it performs its own unsolicited Report for the multicast
address as described in section 5.1 of [RFC3810]. The report is
source independent, so there is no Source Address listed.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| unsolicited Report | | | | unsolicited Report | | |
|------------------->| | | |------------------->| | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | <if not done already> | | | | <if not done already> |
| | | unsolicited Report | | | | unsolicited Report |
| | |---------------------->| | | |---------------------->|
| | | | | | | |
Figure 11: First Multicast Registration Flow Figure 11: First Multicast Registration Flow
This specification does not change MLD but will operate more
efficiently if the asynchronous messages for unsolicited Report and
Done are sent by the 6LN as Layer 2 unicast to the 6LR, particularly
on wireless.
The 6LR acts as a generic MLD querier and generates a DAO with the
multicast address as the Target Prefix as described in Section 12 of
[RFC6550]. As for the unicast host routes, the Path Lifetime
associated to the Target is mapped from the Query Interval and is set
to be larger, to account for variable propagation delays to the root.
The root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the
RPL domain.
Upon a DAO with a Target option for a multicast address, the RPL
DODAG root checks to see if it is already registered as a listener
for that address, and if not, it performs its own unsolicited Report
for the multicast address as described in Section 6.1 of [RFC3810].
The Report is source independent, so there is no source address
listed.
The equivalent of the registration refresh is pulled periodically by The equivalent of the registration refresh is pulled periodically by
the 6LR acting as querier. Upon the timing out of the Query the 6LR acting as the querier. Upon the timing out of the Query
Interval, the 6LR sends a Multicast Address Specific Query to each of Interval, the 6LR sends a Multicast Address Specific Query to each of
its listeners, for each Multicast Address, and gets a Report back its listeners, for each multicast address. The listeners respond
that is mapped into a DAO one by one. Optionally, the 6LR MAY send a with a Report. Based on the Reports, the 6LR maintains the
General Query, where the Multicast Address field is set to zero. In aggregated list of all the multicast addresses for which there is a
that case, the multicast packet is passed as a Layer-2 unicast to listener and advertises them using DAO messages as specified in
each of the interested children. . Section 12 of [RFC6550]. Optionally, the 6LR MAY send a General
Query, where the Multicast Address field is set to 0. In that case,
the multicast packet is passed as a Layer 2 unicast to each of the
interested children.
Upon a Report, the 6LR generates a DAO with as many Target Options as Upon a Report, the 6LR generates a DAO with as many Target options as
there are Multicast Address Records in the Report message, copying there are Multicast Address Records in the Report message, copying
the Multicast Address field in the Target Prefix of the RPL Target the Multicast Address field in the Target Prefix of the RPL Target
Option. The DAO message is a Storing Mode DAO, passed to a selection option. The DAO message is a Storing mode DAO, passed to a selection
of the 6LR's parents. of the 6LR's parents.
Asynchronously to this, a similar procedure happens between the Root Asynchronously to this, a similar procedure happens between the root
and a router such as the 6LBR that serves multicast flows on the Link and a router, such as the 6LBR, that serves multicast flows on the
where the Root is located. Again the Query and Report messages are link where the root is located. Again, the Query and Report messages
source independent. The Root lists exactly once each Multicast are source independent. The root lists exactly once each multicast
Address for which it has at least one active multicast DAO state, address for which it has at least one active multicast DAO state,
copying the multicast address in the DAO state in the Multicast copying the multicast address in the DAO state in the Multicast
Address field of the Multicast Address Records in the Report message. Address field of the Multicast Address Records in the Report message.
This is illustrated in Figure 12: This is illustrated in Figure 12:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
skipping to change at page 33, line 48 skipping to change at line 1538
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
Figure 12: Next Registration Flow Figure 12: Next Registration Flow
Note that any of the functions 6LR, Root and 6LBR might be collapsed Note that all or any combination of the 6LR, the root, and the 6LBR
in a single node, in which case the flow above happens internally, might be collapsed in a single node, in which case the flow above
and possibly through internal API calls as opposed to messaging. happens internally, and possibly through internal API calls as
opposed to messaging.
11. Security Considerations 11. Security Considerations
It is worth noting that with [RFC6550], every node in the LLN is RPL- It is worth noting that with [RFC6550], every node in the LLN is RPL
aware and can inject any RPL-based attack in the network. This aware and can inject any RPL-based attack in the network. This
specification improves the situation by isolating edge nodes that can specification improves this situation by isolating edge nodes that
only interact with the RPL routers using 6LoWPAN ND, meaning that can only interact with the RPL routers using 6LoWPAN ND, meaning that
they cannot perform RPL insider attacks. they cannot perform RPL insider attacks.
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 such threats
as black-holing, (see [RFC7416] section 7), Denial-Of-Service attacks as black-holing (see Section 7 of [RFC7416]), DoS attacks whereby a
whereby a rogue 6LR creates a high churn in the RPL network by rogue 6LR creates a high churn in the RPL network by advertising and
advertising and removing many forged addresses, or bombing attack removing many forged addresses, or a bombing attack whereby an
whereby an impersonated 6LBR would destroy state in the network by impersonated 6LBR would destroy state in the network by using a
using the status code of 4 ("Removed"). status code of 4 ("Removed") [RFC8505].
This trust model could be at a minimum based on a Layer-2 Secure This trust model could be, at a minimum, based on Layer 2 secure
joining and the Link-Layer security. This is a generic 6LoWPAN joining and link-layer security. This is a generic 6LoWPAN
requirement, see Req5.1 in Appendix B.5 of [RFC8505]. requirement; see Req-5.1 in Appendix B.5 of [RFC8505].
In a general manner, the Security Considerations in [RFC6550], In a general manner, the Security Considerations sections of
[RFC7416] [RFC6775], and [RFC8505] apply to this specification as [RFC6550], [RFC7416], [RFC6775], and [RFC8505] apply to this
well. specification as well.
The Link-Layer security is needed in particular to prevent Denial-Of- In particular, link-layer security is needed to prevent DoS attacks
Service attacks whereby a rogue 6LN creates a high churn in the RPL whereby a rogue 6LN creates a high churn in the RPL network by
network by constantly registering and deregistering addresses with constantly registering and deregistering addresses with the R flag
the R Flag set to 1 in the EARO. set to 1 in the EARO.
[RFC8928] updated 6LoWPAN ND with the called Address-Protected [RFC8928] updated 6LoWPAN ND with AP-ND. AP-ND protects the owner of
Neighbor Discovery (AP-ND). AP-ND protects the owner of an address an address against address theft and impersonation attacks in an LLN.
against address theft and impersonation attacks in a Low-Power and Nodes supporting the extension compute a cryptographic identifier
Lossy Network (LLN). Nodes supporting the extension compute a (Crypto-ID) and use it with one or more of their Registered
cryptographic identifier (Crypto-ID), and use it with one or more of Addresses. The Crypto-ID identifies the owner of the Registered
their Registered Addresses. The Crypto-ID identifies the owner of Address and can be used to provide proof of ownership of the
the Registered Address and can be used to provide proof of ownership Registered Addresses. Once an address is registered with the
of the Registered Addresses. Once an address is registered with the Crypto-ID and proof of ownership is provided, only the owner of that
Crypto-ID and a proof of ownership is provided, only the owner of address can modify the registration information, thereby enforcing
that address can modify the registration information, thereby SAVI. [RFC8928] reduces even further the attack perimeter that is
enforcing Source Address Validation. [RFC8928] reduces even more the available to the edge nodes, and its use is suggested in this
attack perimeter that is available to the edge nodes and its use is specification.
suggested in this specification.
Additionally, the trust model could include a role validation (e.g., Additionally, the trust model could include role validation (e.g.,
using a role-based authorization) to ensure that the node that claims using role-based authorization) to ensure that the node that claims
to be a 6LBR or a RPL Root is entitled to do so. to be a 6LBR or a RPL DODAG root is entitled to do so.
The Opaque field in the EARO enables the RUL to suggest a The Opaque field in the EARO enables the RUL to suggest a
RPLInstanceID where its traffic is placed. It is also possible for RPLInstanceID where its traffic is placed. It is also possible for
an attacker RUL to include an RPI in the packet. This opens to an attacker RUL to include an RPI in the packet. This opens the door
attacks where a RPL instance would be reserved for critical traffic, to attacks where a RPL Instance would be reserved for critical
e.g., with a specific bandwidth reservation, that the additional traffic, e.g., with a specific bandwidth reservation, that the
traffic generated by a rogue may disrupt. The attack may be additional traffic generated by a rogue may disrupt. The attack may
alleviated by traditional access control and traffic shaping be alleviated by traditional access control and traffic-shaping
mechanisms where the 6LR controls the incoming traffic from the 6LN. mechanisms where the 6LR controls the incoming traffic from the 6LN.
More importantly, the 6LR is the node that injects the traffic in the More importantly, the 6LR is the node that injects the traffic in the
RPL domain, so it has the final word on which RPLInstance is to be RPL domain, so it has the final word on which RPL Instance is to be
used for the traffic coming from the RUL, per its own policy. In used for the traffic coming from the RUL, per its own policy. In
particular, a policy can override the formal language that forces to particular, a policy can override the formal language that forces the
use the Opaque field or to rewrite the RPI provided by the RUL, in a use of the Opaque field or the rewriting of the RPI provided by the
situation where the network administrator finds it relevant. RUL, in a situation where the network administrator finds it
relevant.
At the time of this writing, RPL does not have a Route Ownership At the time of this writing, RPL does not have a route ownership
Validation model whereby it is possible to validate the origin of an validation model whereby it is possible to validate the origin of an
address that is injected in a DAO. This specification makes a first address that is injected in a DAO. This specification makes a first
step in that direction by allowing the Root to challenge the RUL via step in that direction by allowing the root to challenge the RUL via
the 6LR that serves it. the 6LR that serves it.
Section 6.1 indicates that when the length of the ROVR field is Section 6.1 indicates that when the length of the ROVR field is
unknown, the RPL Target Option must be passed on as received in RPL unknown, the RPL Target option must be passed on as received in RPL
storing Mode. This creates a possible opening for using DAO messages Storing mode. This creates a possible opening for using DAO messages
as a covert channel. Note that DAO messages are rare and overusing as a covert channel. Note that DAO messages are rare, and overusing
that channel could be detected. An implementation SHOULD notify the that channel could be detected. An implementation SHOULD notify the
network management when a RPL Target Option is receives with an network management system when a RPL Target option is received with
unknown ROVR field size, to ensure that the situation is known to the an unknown ROVR field size, to ensure that the network administrator
network administrator. is aware of the situation.
[EFFICIENT-NPDAO] introduces the ability for a rogue common ancestor [RFC9009] introduces the ability for a rogue common ancestor node to
node to invalidate a route on behalf of the target node. In this invalidate a route on behalf of the target node. In this case, the
case, the RPL Status in the DCO has the 'A' flag set to 0, and a RPL Status in the DCO has the 'A' flag set to 0, and an NA(EARO) is
NA(EARO) is returned to the 6LN with the R flag set to 0. This returned to the 6LN with the R flag set to 0. This encourages the
encourages the 6LN to try another 6LR. If a 6LR exists that does not 6LN to try another 6LR. If a 6LR exists that does not use the rogue
use the rogue common ancestor, then the 6LN will eventually succeed common ancestor, then the 6LN will eventually succeed gaining
gaining reachability over the RPL network in spite of the rogue node. reachability over the RPL network in spite of the rogue node.
12. IANA Considerations 12. IANA Considerations
12.1. 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] created a registry for the 8-bit Address
Registration Option Flags field. IANA is requested to rename the Registration Option Flags field. IANA has renamed the first column
first column of the table from "ARO Status" to "Bit number". of the table from "ARO Status" to "Bit Number".
12.2. 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] created the "Address Registration Option
Status values Registry with a range 0-255. Status Values" registry with a range of 0-255.
This specification reduces that range to 0-63, see Section 6.3. This specification reduces that range to 0-63; see Section 6.3.
IANA is requested to modify the Address Registration Option Status IANA has modified the "Address Registration Option Status Values"
values Registry so that the upper bound of the unassigned values is registry so that the upper bound of the unassigned values is 63.
63. This document should be added as a reference. The registration This document has been added as a reference. The registration
procedure does not change. procedure has not changed.
12.3. New RPL DODAG Configuration Option Flag 12.3. New RPL DODAG Configuration Option Flag
IANA is requested to assign a flag from the "DODAG Configuration IANA has assigned the following flag in the "DODAG Configuration
Option Flags for MOP 0..6" [USEofRPLinfo] registry as follows: Option Flags for MOP 0..6" registry [RFC9008]:
+---------------+----------------------------+-----------+ +------------+----------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+---------------+----------------------------+-----------+ +------------+----------------------------+-----------+
| 1 (suggested) | Root Proxies EDAR/EDAC (P) | THIS RFC | | 1 | Root Proxies EDAR/EDAC (P) | RFC 9010 |
+---------------+----------------------------+-----------+ +------------+----------------------------+-----------+
Table 2: New DODAG Configuration Option Flag Table 2: New DODAG Configuration Option Flag
IANA is requested to add [this document] as a reference for MOP 7 in IANA has added this document as a reference for MOP 7 in the RPL
the RPL Mode of Operation registry. "Mode of Operation" registry.
12.4. RPL Target Option Registry 12.4. RPL Target Option Flags Registry
This document modifies the "RPL Target Option Flags" registry This document modifies the "RPL Target Option Flags" registry
initially created in Section 20.15 of [RFC6550] . The registry now initially created per Section 20.15 of [RFC6550]. The registry now
includes only 4 bits (Section 6.1) and should point to this document includes only 4 bits (Section 6.1) and lists this document as an
as an additional reference. The registration procedure does not additional reference. The registration procedure has not changed.
change.
Section 6.1 also defines 2 new entries in the Registry as follows: Section 6.1 also defines two new entries in the registry, as follows:
+---------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+---------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
| 0 (suggested) | Advertiser address in Full (F) | THIS RFC | | 0 | Advertiser address in Full (F) | RFC 9010 |
+---------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
| 1 (suggested) | Proxy EDAR Requested (X) | THIS RFC | | 1 | Proxy EDAR Requested (X) | RFC 9010 |
+---------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
Table 3: RPL Target Option Registry Table 3: RPL Target Option Flags Registry
12.5. New Subregistry for RPL Non-Rejection Status values 12.5. New Subregistry for RPL Non-Rejection Status Values
This specification creates a new Subregistry for the RPL Non- IANA has created a new subregistry for the RPL Non-Rejection Status
Rejection Status values for use in the RPL DAO-ACK, DCO, and DCO-ACK values for use in the RPL DAO-ACK, DCO, and DCO-ACK messages with the
messages with the 'A' flag set to 0, under the RPL registry. 'A' flag set to 0 and the 'U' flag set to 1, under the "Routing
Protocol for Low Power and Lossy Networks (RPL)" registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "IETF Review" [RFC8126]. * The registration procedure is IETF Review [RFC8126].
* Initial allocation is as indicated in Table 4: * The initial allocation is as indicated in Table 4:
+-------+------------------------+---------------------+ +-------+----------------------------------+---------------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+------------------------+---------------------+ +-------+----------------------------------+---------------------+
| 0 | Unqualified acceptance | THIS RFC / RFC 6550 | | 0 | Success / Unqualified acceptance | RFC 6550 / RFC 9010 |
+-------+------------------------+---------------------+ +-------+----------------------------------+---------------------+
| 1..63 | Unassigned | | | 1..63 | Unassigned | |
+-------+------------------------+---------------------+ +-------+----------------------------------+---------------------+
Table 4: Acceptance values of the RPL Status Table 4: Acceptance Values of the RPL Status
12.6. New Subregistry for RPL Rejection Status values 12.6. New Subregistry for RPL Rejection Status Values
This specification creates a new Subregistry for the RPL Rejection IANA has created a new subregistry for the RPL Rejection Status
Status values for use in the RPL DAO-ACK and DCO messages with the values for use in the RPL DAO-ACK and DCO messages with the 'A' flag
'A' flag set to 0, under the RPL registry. set to 0 and the 'U' flag set to 1, under the "Routing Protocol for
Low Power and Lossy Networks (RPL)" registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "IETF Review" [RFC8126]. * The registration procedure is IETF Review [RFC8126].
* Initial allocation is as indicated in Table 5:
+--------------------+-----------------------+-------------------+ * The initial allocation is as indicated in Table 5:
| Value | Meaning | Reference |
+--------------------+-----------------------+-------------------+
| 0 | Unqualified rejection | THIS RFC |
+--------------------+-----------------------+-------------------+
| 1 (suggested in | No routing entry | [EFFICIENT-NPDAO] |
| [EFFICIENT-NPDAO]) | | |
+--------------------+-----------------------+-------------------+
| 2..63 | Unassigned | |
+--------------------+-----------------------+-------------------+
Table 5: Rejection values of the RPL Status +-------+-----------------------+-----------+
| Value | Meaning | Reference |
+-------+-----------------------+-----------+
| 0 | Unqualified rejection | RFC 9010 |
+-------+-----------------------+-----------+
| 1 | No routing entry | RFC 9009 |
+-------+-----------------------+-----------+
| 2..63 | Unassigned | |
+-------+-----------------------+-----------+
13. Acknowledgments Table 5: Rejection Values of the RPL Status
The authors wish to thank Ines Robles, Georgios Papadopoulos and 13. References
especially Rahul Jadhav and Alvaro Retana for their reviews and
contributions to this document. Also many thanks to Eric Vyncke,
Erik Kline, Murray Kucherawy, Peter Van der Stok, Carl Wallace, Barry
Leiba, Julien Meuric, and especially Benjamin Kaduk and Elwyn Davies,
for their reviews and useful comments during the IETF Last Call and
the IESG review sessions.
14. Normative References 13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810, Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
DOI 10.17487/RFC3810, June 2004, DOI 10.17487/RFC3810, June 2004,
<https://www.rfc-editor.org/info/rfc3810>. <https://www.rfc-editor.org/info/rfc3810>.
skipping to change at page 39, line 34 skipping to change at line 1802
Perkins, "Registration Extensions for IPv6 over Low-Power Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik, [RFC8928] Thubert, P., Ed., 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", RFC 8928, DOI 10.17487/RFC8928, November Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November
2020, <https://www.rfc-editor.org/info/rfc8928>. 2020, <https://www.rfc-editor.org/info/rfc8928>.
[USEofRPLinfo] [RFC9008] Robles, M.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-
Option Type, Routing Header for Source Routes and IPv6-in- in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008,
IPv6 encapsulation in the RPL Data Plane", Work in DOI 10.17487/RFC9008, April 2021,
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-43, <https://www.rfc-editor.org/info/rfc9008>.
10 January 2021, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-43>.
[EFFICIENT-NPDAO] [RFC9009] Jadhav, R.A., Ed., Thubert, P., Sahoo, R.N., and Z. Cao,
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient "Efficient Route Invalidation", RFC 9009,
Route Invalidation", Work in Progress, Internet-Draft, DOI 10.17487/RFC9009, April 2021,
draft-ietf-roll-efficient-npdao-18, 15 April 2020, <https://www.rfc-editor.org/info/rfc9009>.
<https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-18>.
15. Informative References 13.2. Informative References
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs): over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals", Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007, RFC 4919, DOI 10.17487/RFC4919, August 2007,
<https://www.rfc-editor.org/info/rfc4919>. <https://www.rfc-editor.org/info/rfc4919>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Address Autoconfiguration", RFC 4862, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc6282>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553, Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012, DOI 10.17487/RFC6553, March 2012,
<https://www.rfc-editor.org/info/rfc6553>. <https://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012, DOI 10.17487/RFC6554, March 2012,
<https://www.rfc-editor.org/info/rfc6554>. <https://www.rfc-editor.org/info/rfc6554>.
[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>.
[RFC6687] Tripathi, J., Ed., de Oliveira, J., Ed., and JP. Vasseur,
Ed., "Performance Evaluation of the Routing Protocol for
Low-Power and Lossy Networks (RPL)", RFC 6687,
DOI 10.17487/RFC6687, October 2012,
<https://www.rfc-editor.org/info/rfc6687>.
[RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed., [RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed.,
"Source Address Validation Improvement (SAVI) Framework", "Source Address Validation Improvement (SAVI) Framework",
RFC 7039, DOI 10.17487/RFC7039, October 2013, RFC 7039, DOI 10.17487/RFC7039, October 2013,
<https://www.rfc-editor.org/info/rfc7039>. <https://www.rfc-editor.org/info/rfc7039>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>.
[RFC6687] Tripathi, J., Ed., de Oliveira, J., Ed., and JP. Vasseur,
Ed., "Performance Evaluation of the Routing Protocol for
Low-Power and Lossy Networks (RPL)", RFC 6687,
DOI 10.17487/RFC6687, October 2012,
<https://www.rfc-editor.org/info/rfc6687>.
[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
and M. Richardson, Ed., "A Security Threat Analysis for and M. Richardson, Ed., "A Security Threat Analysis for
the Routing Protocol for Low-Power and Lossy Networks the Routing Protocol for Low-Power and Lossy Networks
(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
<https://www.rfc-editor.org/info/rfc7416>. <https://www.rfc-editor.org/info/rfc7416>.
[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch", Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016, RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>. <https://www.rfc-editor.org/info/rfc8025>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
[RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli, [RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli,
"IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929, "IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929,
November 2020, <https://www.rfc-editor.org/info/rfc8929>. November 2020, <https://www.rfc-editor.org/info/rfc8929>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 13 illustrates the case in Storing Mode where the packet is Figure 13 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 it to the 6LR that is the parent and last
to the final destination, which is not known to support [RFC8138]. hop 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 13: Encapsulation to Parent 6LR in Storing Mode Figure 13: Encapsulation to Parent 6LR in Storing Mode
The difference with the example presented in Figure 19 of [RFC8138] The difference from 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 an 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 [RFC8138] example the destination IP of the IPv6 header. In Figure 19 of [RFC8138], the destination IP of the
outer header was elided and was implicitly the same address as the outer 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 13, the source of the IPv6-in-IPv6 encapsulation is the In Figure 13, the source of the IPv6-in-IPv6 encapsulation is the
Root, so it is elided in the IPv6-in-IPv6 6LoRH. The destination is root, so it is elided in the IPv6-in-IPv6 6LoRH. The destination is
the parent 6LR of the destination of the encapsulated packet so it the parent 6LR of the destination of the encapsulated packet, so it
cannot be elided. If the DODAG is operated in Storing Mode, it is cannot be elided. If the DODAG is operated in Storing mode, it is
the single entry in the SRH-6LoRH and the SRH-6LoRH Size is encoded the single entry in the SRH-6LoRH and the SRH-6LoRH Size is encoded
as 0. The SRH-6LoRH is the first 6LoRH in the chain. In this as 0. The SRH-6LoRH is the first 6LoRH in the chain. In this
particular example, the 6LR address can be compressed to 2 bytes so a particular example, the 6LR address can be compressed to 2 bytes, so
Type of 1 is used. It results that the total length of the SRH-6LoRH a Type of 1 is used. The result is that the total length of the SRH-
is 4 bytes. 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 13 with possibly more hops in the SRH- to that represented in Figure 13 with possibly more hops in the
6LoRH and possibly multiple SRH-6LoRHs if the various addresses in SRH-6LoRH and possibly multiple SRH-6LoRHs if the various addresses
the routing header are not compressed to the same format. Note that in the routing header are not compressed to the same format. Note
on the last hop to the parent 6LR, the RH3 is consumed and removed that on the last hop to the parent 6LR, the RH3 is consumed and
from the compressed form, so the use of Non-Storing Mode vs. Storing removed from the compressed form, so the use of Non-Storing mode
Mode is indistinguishable from the packet format. vs. Storing mode is indistinguishable from the packet format.
The SRH-6LoRHs are followed by RPI-6LoRH and then the IPv6-in-IPv6 The SRH-6LoRHs are followed by the RPI-6LoRH and then the IPv6-in-
6LoRH. When the IPv6-in-IPv6 6LoRH is removed, all the 6LoRH Headers IPv6 6LoRH. When the IPv6-in-IPv6 6LoRH is removed, all the 6LoRH
that precede it are also removed. The Paging Dispatch [RFC8025] may Headers that precede it are also removed. The Paging Dispatch
also be removed if there was no previous Page change to a Page other [RFC8025] may also be removed if there was no previous Page change to
than 0 or 1, since the LOWPAN_IPHC is encoded in the same fashion in a Page other than 0 or 1, since the LOWPAN_IPHC is encoded in the
the default Page 0 and in Page 1. The resulting packet to the same fashion in the default Page 0 and in Page 1. The resulting
destination is the encapsulated packet compressed with [RFC6282]. packet to the destination is the encapsulated packet compressed per
[RFC6282].
Acknowledgments
The authors wish to thank Ines Robles, Georgios Papadopoulos, and
especially Rahul Jadhav and Alvaro Retana for their reviews and
contributions to this document. Also many thanks to √Čric Vyncke,
Erik Kline, Murray Kucherawy, Peter van der Stok, Carl Wallace, Barry
Leiba, Julien Meuric, and especially Benjamin Kaduk and Elwyn Davies,
for their reviews and useful comments during the IETF Last Call and
the IESG review sessions.
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc.
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
06254 Mougins - Sophia Antipolis 06254 MOUGINS - Sophia Antipolis
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Michael C. Richardson Michael C. Richardson
Sandelman Software Works Sandelman Software Works
Email: mcr+ietf@sandelman.ca Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/ URI: https://www.sandelman.ca/
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