draft-ietf-roll-unaware-leaves-21.txt   draft-ietf-roll-unaware-leaves-22.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550, 8505 (if approved) M. Richardson Updates: 6550, 6775, 8505 (if approved) M. Richardson
Intended status: Standards Track Sandelman Intended status: Standards Track Sandelman
Expires: 3 April 2021 30 September 2020 Expires: 12 April 2021 9 October 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-21 draft-ietf-roll-unaware-leaves-22
Abstract Abstract
This specification extends RFC6550 and RFC8505 to provide routing This specification updates RFC6550, RFC6775, and RFC8505, to provide
services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND routing services to RPL Unaware Leaves that implement 6LoWPAN ND and
but do not participate in RPL. This specification also enables the the extensions therein.
RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 April 2021. This Internet-Draft will expire on 12 April 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 2, line 17 skipping to change at page 2, line 17
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. References . . . . . . . . . . . . . . . . . . . . . . . 6 2.3. References . . . . . . . . . . . . . . . . . . . . . . . 6
3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 7 3. RPL External Routes and Dataplane Artifacts . . . . . . . . . 7
4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 8 4. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 8
4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 8 4.1. RFC 6775 Address Registration . . . . . . . . . . . . . . 8
4.2. RFC 8505 Extended Address Registration . . . . . . . . . 8 4.2. RFC 8505 Extended Address Registration . . . . . . . . . 8
4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 9 4.2.1. R Flag . . . . . . . . . . . . . . . . . . . . . . . 9
4.2.2. TID, I Field and Opaque Fields . . . . . . . . . . . 9 4.2.2. TID, "I" Field and Opaque Fields . . . . . . . . . . 9
4.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2.3. ROVR . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 10 4.3. RFC 8505 Extended DAR/DAC . . . . . . . . . . . . . . . . 10
4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 10 4.3.1. RFC 7400 Capability Indication Option . . . . . . . . 10
5. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11 5. Requirements on the RPL-Unware Leaf . . . . . . . . . . . . . 11
5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11 5.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11
5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 11 5.2. Support of IPv6 Encapsulation . . . . . . . . . . . . . . 12
5.3. Support of the HbH Header . . . . . . . . . . . . . . . . 12 5.3. Support of the HbH Header . . . . . . . . . . . . . . . . 12
5.4. Support of the Routing Header . . . . . . . . . . . . . . 12 5.4. Support of the Routing Header . . . . . . . . . . . . . . 12
6. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 12 6. Enhancements to RFC 6550 . . . . . . . . . . . . . . . . . . 12
6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 13 6.1. Updated RPL Target Option . . . . . . . . . . . . . . . . 13
6.2. Updated DODAG Configuration Option . . . . . . . . . . . 14 6.2. New Flag in the RPL DODAG Configuration Option . . . . . 14
6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 15 6.3. Updated RPL Status . . . . . . . . . . . . . . . . . . . 15
7. Updating draft-ietf-roll-efficient-npdao . . . . . . . . . . 16 7. Enhancements to draft-ietf-roll-efficient-npdao . . . . . . . 16
8. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 16 8. Enhancements to RFC 6775 and RFC8505 . . . . . . . . . . . . 17
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 16 9. Protocol Operations for Unicast Addresses . . . . . . . . . . 17
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 17 9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 18
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19 9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 20
9.2.1. Perspective of the RUL Acting as 6LN . . . . . . . . 19 9.2.1. Perspective of the 6LN Acting as RUL . . . . . . . . 20
9.2.2. Perspective of the Border Router Acting as 6LR . . . 20 9.2.2. Perspective of the 6LR Acting as Border Router . . . 22
9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 23 9.2.3. Perspective of the RPL Root . . . . . . . . . . . . . 26
9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 23 9.2.4. Perspective of the 6LBR . . . . . . . . . . . . . . . 27
10. Protocol Operations for Multicast Addresses . . . . . . . . . 24 10. Protocol Operations for Multicast Addresses . . . . . . . . . 27
11. Security Considerations . . . . . . . . . . . . . . . . . . . 25 11. Security Considerations . . . . . . . . . . . . . . . . . . . 29
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
12.1. Fixing the Address Registration Option Flags . . . . . . 26 12.1. Fixing the Address Registration Option Flags . . . . . . 31
12.2. Resizing the ARO Status values . . . . . . . . . . . . . 26 12.2. Resizing the ARO Status values . . . . . . . . . . . . . 31
12.3. New DODAG Configuration Option Flag . . . . . . . . . . 27 12.3. New DODAG Configuration Option Flag . . . . . . . . . . 31
12.4. New RPL Target Option Flag . . . . . . . . . . . . . . . 27 12.4. RPL Target Option Registry . . . . . . . . . . . . . . . 31
12.5. New Subregistry for the RPL Non-Rejection Status 12.5. New Subregistry for the RPL Non-Rejection Status
values . . . . . . . . . . . . . . . . . . . . . . . . . 27 values . . . . . . . . . . . . . . . . . . . . . . . . . 32
12.6. New Subregistry for the RPL Rejection Status values . . 28 12.6. New Subregistry for the RPL Rejection Status values . . 32
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33
14. Normative References . . . . . . . . . . . . . . . . . . . . 28 14. Normative References . . . . . . . . . . . . . . . . . . . . 33
15. Informative References . . . . . . . . . . . . . . . . . . . 31 15. Informative References . . . . . . . . . . . . . . . . . . . 35
Appendix A. Example Compression . . . . . . . . . . . . . . . . 32 Appendix A. Example Compression . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices and low-power lossy transmissions, duty cycling of the LLN devices and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced the "Routing Protocol for Low Power and Lossy The IETF produced the "Routing Protocol for Low Power and Lossy
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forwarding solutions towards the Root of the topology via so-called forwarding solutions towards the Root of the topology via so-called
parents. RPL is designed to adapt to fuzzy connectivity, whereby the parents. RPL is designed to adapt to fuzzy connectivity, whereby the
physical topology cannot be expected to reach a stable state, with a physical topology cannot be expected to reach a stable state, with a
lazy control that creates the routes proactively, but may only fix lazy control that creates the routes proactively, but may only fix
them reactively, upon actual traffic. The result is that RPL them reactively, upon actual traffic. The result is that RPL
provides reachability for most of the LLN nodes, most of the time, provides reachability for most of the LLN nodes, most of the time,
but may not converge in the classical sense. but may not converge in the classical sense.
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 6LoWPAN ND [RFC6775] [RFC8505] to maintain
reachability within a Non-Broadcast Multi-Access (NBMA) Multi-Link reachability within a Non-Broadcast Multi- (NBMA) Multi-Link subnet.
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 to the routes. Some nodes may act as Routers and participate in the
forwarding operations whereas others will only terminate packets, forwarding operations whereas others will only terminate packets,
acting as Hosts in the data-plane. In [RFC6550] terms, an IPv6 Host acting as Hosts in the data-plane. In [RFC6550] terms, an IPv6 Host
[RFC8504] that is reachable over the RPL network is called a Leaf. [RFC8504] that is reachable over the RPL network is called a Leaf.
[USEofRPLinfo] introduces the terms RPL-Aware-Leaf (RAL) and RPL- [USEofRPLinfo] introduces the terms RPL-Aware-Leaf (RAL) and RPL-
Unaware Leaf (RUL). A RAL is a Leaf that injects Host routes in RPL Unaware Leaf (RUL). A RAL is a Leaf that injects Host routes in RPL
to manage the reachability of its IPv6 addresses. Conversely, a RUL to manage the reachability of its IPv6 addresses. Conversely, a RUL
does not participate to RPL and cannot inject its Host routes in RPL. does not participate to RPL and cannot inject routes. Section 5
The RUL therefore needs a Host-to-Router interface to advertise its details a Host-to-Router interface that the RUL needs to implement to
IPv6 addresses to its access Router so the Router can inject them the advertise its IPv6 addresses to a Router that supports this
RPL network on its behalf. Section 5 details the interface needed by specification. The document specifies how the Router injects those
a router that implements this specification. addresses as Host routes in the RPL network on behalf of the RUL.
This specification leverages the Address Registration mechanism This specification leverages the Address Registration mechanism
defined in 6LoWPAN ND to enable a RUL acting as a 6LoWPAN Node (6LN) defined in 6LoWPAN ND to enable a 6LoWPAN Node (6LN) acting as a RUL
to interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) and to interface with a 6LoWPAN Router (6LR) that is RPL-Aware router,
request that the 6LR injects a Host route for the Registered Address and request that the router injects a Host route for the Registered
in the RPL routing on its behalf. A RUL may be unable to participate Address in RPL on its behalf. A RUL may be unable to participate
because it is very energy-constrained, or because it is unsafe to let because it is very energy-constrained, or because it is unsafe to let
it inject routes in RPL, in which case using 6LowPAN ND as the it inject routes in RPL, in which case using 6LowPAN ND as the
interface for the RUL limits the surface of the possible attacks and interface for the RUL limits the surface of the possible attacks and
optionally protects the address ownership. optionally protects the address ownership.
The RPL Non-Storing Mode mechanism is used to extend the routing The RPL Non-Storing Mode mechanism is used to extend the routing
state with connectivity to the RULs even when the DODAG is operated state with connectivity to the RULs even when the DODAG is operated
in Storing Mode. The unicast packet forwarding operation by the 6LR in Storing Mode. The unicast packet forwarding operation by the 6LR
serving a RUL is described in section 4.1 of [USEofRPLinfo]. serving a RUL is described in section 4.1 of [USEofRPLinfo].
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This document is organized as follows: This document is organized as follows:
* Section 3 and Section 4 present salient aspects of RPL and 6LoWPAN * Section 3 and Section 4 present salient aspects of RPL and 6LoWPAN
ND, respectively, that are leveraged in this specification to ND, respectively, that are leveraged in this specification to
provide connectivity to a RUL across a RPL network. provide connectivity to a RUL across a RPL network.
* Section 5 lists the expectations that a RUL needs to match in * Section 5 lists the expectations 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, Section 7, and Section 8 present the additions made to * Section 6, Section 7, and Section 8 present the changes made to
[RFC6550], [EFFICIENT-NPDAO], and [RFC8505]. [RFC6550], [EFFICIENT-NPDAO], [RFC6775] and [RFC8505].
* Section 9 and Section 10 present the operation of this * Section 9 and Section 10 present the operation of this
specification for unicast and multicast flows, respectively, and specification for unicast and multicast flows, respectively, and
Section 11 presents associated security considerations. Section 11 presents 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",
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and and
6LoWPAN ND: Neighbor Discovery Optimization for Low-Power and Lossy 6LoWPAN ND: Neighbor Discovery Optimization for Low-Power and Lossy
Networks [RFC6775], "Registration Extensions for 6LoWPAN Neighbor Networks [RFC6775], "Registration Extensions for 6LoWPAN Neighbor
Discovery" [RFC8505], and "Address Protected Neighbor Discovery Discovery" [RFC8505], and "Address Protected Neighbor Discovery
for Low-power and Lossy Networks" [AP-ND]. for Low-power and Lossy Networks" [AP-ND].
3. RPL External Routes and Dataplane Artifacts 3. RPL External Routes and Dataplane Artifacts
Section 4.1 of [USEofRPLinfo] provides a set of rules detailed below Section 4.1 of [USEofRPLinfo] provides a set of rules detailed below
that MUST be followed for routing packets from and to a RUL. that must be followed for routing packets from and to a RUL.
A 6LR that acts as a border Router for external routes advertises A 6LR that acts as a border Router for external routes advertises
them using Non-Storing Mode DAO messages that are unicast directly to them using Non-Storing Mode DAO messages that are unicast directly to
the Root, even if the DODAG is operated in Storing Mode. Non-Storing the Root, even if the DODAG is operated in Storing Mode. Non-Storing
Mode routes are not visible inside the RPL domain and all packets are Mode routes are not visible inside the RPL domain and all packets are
routed via the Root. The RPL Root tunnels the packets directly to routed via the Root. The RPL Root tunnels the packets directly to
the 6LR that advertised the external route, which decapsulates and the 6LR that advertised the external route, which decapsulates and
forwards the original (inner) packet. forwards the original (inner) packet.
The RPL Non-Storing MOP signaling and the associated IP-in-IP The RPL Non-Storing MOP signaling and the associated IP-in-IP
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does not add to the amount of state that must be maintained in those does not add to the amount of state that must be maintained in those
Routers. A RUL is an example of a destination that is reachable via Routers. A RUL is an example of a destination that is reachable via
an external route that happens to be also a Host route. an external route that happens to be also a Host route.
The RPL data packets always carry a Hop-by-Hop Header to transport a The RPL data packets always carry a Hop-by-Hop Header to transport a
RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates RPL Packet Information (RPI) [RFC6550]. So unless the RUL originates
its packets with an RPI, the 6LR needs to tunnel them to the Root to its packets with an RPI, the 6LR needs to tunnel them to the Root to
add the RPI. As a rule of a thumb and except for the very special add the RPI. As a rule of a thumb and except for the very special
case above, the packets from and to a RUL are always encapsulated case above, the packets from and to a RUL are always encapsulated
using an IP-in-IP tunnel between the Root and the 6LR that serves the using an IP-in-IP tunnel between the Root and the 6LR that serves the
RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4, RUL (see sections 7 and 8 of [USEofRPLinfo] for details).
8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details).
In Non-Storing Mode, packets going down carry a Source Routing Header In Non-Storing Mode, packets going down carry a Source Routing Header
(SRH). The IP-in-IP encapsulation, the RPI and the SRH are (SRH). The IP-in-IP encapsulation, the RPI and the SRH are
collectively called the "RPL artifacts" and can be compressed using collectively called the "RPL artifacts" and can be compressed using
[RFC8138]. Figure 11 presents an example compressed format for a [RFC8138]. Appendix A presents an example compressed format for a
packet forwarded by the Root to a RUL in a Storing Mode DODAG. packet forwarded by the Root to a RUL in a Storing Mode DODAG.
The inner packet that is forwarded to the RUL may carry some RPL The inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it, artifacts, e.g., an RPI if the original packet was generated with it,
and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the and an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] expects the
RUL to support the basic "IPv6 Node Requirements" [RFC8504]. In RUL to support the basic "IPv6 Node Requirements" [RFC8504]. In
particular the RUL is expected to ignore the RPL artifacts that are particular the RUL is expected to ignore the RPL artifacts that are
either consumed or not applicable to a Host. either consumed or not applicable to a Host.
A RUL is not expected to support the compression method defined in A RUL is not expected to support the compression method defined in
[RFC8138]. Unless configured otherwise, the border Router MUST [RFC8138]. For that reason, the border router uncompresses the
restore the outgoing packet before forwarding over an external route, packet before forwarding over an external route to a RUL
even if it is not the destination of the incoming packet, and even [USEofRPLinfo].
when delivering to a RUL.
4. 6LoWPAN Neighbor Discovery 4. 6LoWPAN Neighbor Discovery
4.1. RFC 6775 Address Registration 4.1. RFC 6775 Address Registration
The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861] The classical "IPv6 Neighbor Discovery (IPv6 ND) Protocol" [RFC4861]
[RFC4862] was defined for serial links and transit media such as [RFC4862] was defined for serial links and transit media such as
Ethernet. It is a reactive protocol that relies heavily on multicast Ethernet. It is a reactive protocol that relies heavily on multicast
operations for address discovery (aka lookup) and duplicate address operations for Address Discovery (aka Lookup) and Duplicate Address
detection (DAD). Detection (DAD).
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
adapts IPv6 ND for operations over energy-constrained LLNs. The main adapts IPv6 ND for operations over energy-constrained LLNs. The main
functions of [RFC6775] are to proactively establish the Neighbor functions of [RFC6775] are to proactively establish the Neighbor
Cache Entry (NCE) in the 6LR and to prevent address duplication. To Cache Entry (NCE) in the 6LR and to prevent address duplication. To
that effect, [RFC6775] introduces a new unicast Address Registration that effect, [RFC6775] introduces a new unicast Address Registration
mechanism that contributes to reducing the use of multicast messages mechanism that contributes to reducing the use of multicast messages
compared to the classical IPv6 ND protocol. compared to the classical IPv6 ND protocol.
[RFC6775] defines a new Address Registration Option (ARO) that is [RFC6775] defines a new Address Registration Option (ARO) that is
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier ... ... Registration Ownership Verifier ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Option Format Figure 1: EARO Option 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 not set, reachability for the Registered Address. If the R Flag is not set,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means. In a RPL network, this means that either it Address by other means. In a RPL network, this means that either it
is a RAN that injects the route by itself or that it uses another RPL is a RAN that injects the route by itself or that it uses another RPL
Router for reachability services. Router for reachability services.
This document specifies how the "R" flag is used in the context of This document specifies how the R Flag is used in the context of RPL.
RPL. A RPL Leaf that implements the 6LN functionality in [RFC8505] A RPL Leaf that implements the 6LN functionality in [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 sets the R Flag in the NS(EARO) used to register the address to a 6LR
RPL border Router acting as 6LR. Upon receiving the NS(EARO), the acting as a RPL border Router. Upon receiving the NS(EARO), the RPL
RPL Router generates a DAO message for the Registered Address if and Router generates a DAO message for the Registered Address if and only
only if the "R" flag is set. More in Section 9.2. if the R flag is set.
4.2.2. TID, I Field and Opaque Fields Section 9.2 specifies additional operations when R flag is set in an
EARO that is placed either in an NS or an NA message.
When the "T" flag is set, the EARO includes a sequence counter called 4.2.2. TID, "I" Field and Opaque Fields
When the T Flag is set, the EARO includes a sequence counter called
Transaction ID (TID), that is needed to fill the Path Sequence Field Transaction ID (TID), that is needed to fill the Path Sequence Field
in the RPL Transit Option. This is the reason why the support of in the RPL Transit Option. This is the reason why the support of
[RFC8505] by the RUL, as opposed to only [RFC6775] is a prerequisite [RFC8505] by the RUL, as opposed to only [RFC6775] is a prerequisite
for this specification (more in Section 5.1). The EARO also for this specification (more in Section 5.1). The EARO also
transports an Opaque field and an associated "I" field that describes transports an Opaque field and an associated "I" field that describes
what the Opaque field transports and how to use it. Section 9.2.1 what the Opaque field transports and how to use it.
specifies the use of the "I" field and the Opaque field by a RUL.
Section 9.2.1 specifies the use of the "I" field and the Opaque field
by a RUL.
4.2.3. ROVR 4.2.3. ROVR
Section 5.3 of [RFC8505] introduces the Registration Ownership Section 5.3 of [RFC8505] introduces the Registration Ownership
Verifier (ROVR) field of variable length from 64 to 256 bits. The Verifier (ROVR) field of variable length from 64 to 256 bits. The
ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was ROVR is a replacement of the EUI-64 in the ARO [RFC6775] that was
used to identify uniquely an Address Registration with the Link-Layer used to identify uniquely an Address Registration with the Link-Layer
address of the owner but provided no protection against spoofing. address of the owner but provided no protection against spoofing.
"Address Protected Neighbor Discovery for Low-power and Lossy "Address Protected Neighbor Discovery for Low-power and Lossy
Networks" [AP-ND] leverages the ROVR field as a cryptographic proof Networks" [AP-ND] leverages the ROVR field as a cryptographic proof
of ownership to prevent a rogue third party from misusing the of ownership to prevent a rogue third party from registering an
address. [AP-ND] adds a challenge/response exchange to the [RFC8505] address that is already owned and enable the 6LR to block traffic
Address Registration and enables Source Address Validation by a 6LR. that is not sourced at a owned address.
This specification does not address how the protection by [AP-ND] This specification does not address how the protection by [AP-ND]
could be extended for the use of RPL. On the other hand, it adds the could be extended for use in RPL. On the other hand, it adds the
ROVR to the DAO to build the proxied EDAR at the Root (see 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. RFC 8505 Extended DAR/DAC
[RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to [RFC8505] updates the DAR/DAC messages into the Extended DAR/DAC to
carry the ROVR field. The EDAR/EDAC exchange takes place between the carry the ROVR field. The EDAR/EDAC exchange takes place between the
6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN 6LR and the 6LBR. It is triggered by an NS(EARO) message from a 6LN
to create, refresh, and delete the corresponding state in the 6LBR. to create, refresh, and delete the corresponding state in the 6LBR.
skipping to change at page 10, line 28 skipping to change at page 10, line 34
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. the 6LBR on behalf of the 6LR, as illustrated in Figure 7.
4.3.1. RFC 7400 Capability Indication Option 4.3.1. RFC 7400 Capability Indication Option
"6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power "6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the
6LoWPAN Capability Indication Option (6CIO) that enables a node to 6LoWPAN Capability Indication Option (6CIO) that enables a node to
expose its capabilities in Router Advertisement (RA) messages. expose its capabilities in Router Advertisement (RA) messages.
[RFC8505] defines a number of bits in the 6CIO, in particular: [RFC8505] defines a number of bits in the 6CIO, in particular:
L: Node is a 6LR. L: Node is a 6LR.
E: Node is an IPv6 ND Registrar -- i.e., it supports registrations E: Node is an IPv6 ND Registrar -- i.e., it supports registrations
based on EARO. based on EARO.
P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that
also provides reachability services for the Registered Address. 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
skipping to change at page 11, line 20 skipping to change at page 11, line 30
This document provides RPL routing for a RUL. This section describes This document provides RPL routing for a RUL. This section describes
the minimal RPL-independent functionality that the RUL needs to the minimal RPL-independent functionality that the RUL needs to
implement to obtain routing services for its addresses. implement to obtain 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 set the "R" and specification, a RUL needs to implement [RFC8505] and set the "R" and
"T" flags in the EARO as discussed in Section 4.2.1 and "T" flags in the EARO as discussed in Section 4.2.1 and
Section 4.2.3, respectively. The RUL is expected not to request Section 4.2.3, respectively. Section 9.2.1 specifies new behaviors
routing services from a Router that does not originate RA messages for the RUL, e.g., when the R Flag set in a NS(EARO) is not echoed in
with a CIO that has the L, P, and E flags all set as discussed in the NA(EARO), which indicates that the route injection failed.
Section 4.3.1, unless configured to do so. It is suggested that the
RUL also implements [AP-ND] to protect the ownership of its The RUL is expected not to request routing services from a Router
addresses. that does not originate RA messages with a CIO that has the L, P, and
E flags all set as discussed in Section 4.3.1, unless configured to
do so. It is suggested that the RUL also implements [AP-ND] to
protect the ownership of its addresses.
A RUL that may attach to multiple 6LRs is expected to prefer those A RUL that may attach to multiple 6LRs is expected to prefer those
that provide routing services. The RUL needs to register to all the that provide routing services. The RUL needs to register to all the
6LRs from which it desires routing services. 6LRs from which it desires routing services.
Parallel Address Registrations to several 6LRs should be performed in Parallel Address Registrations to several 6LRs should be performed in
an rapid sequence, using the exact same EARO for the same Address. a rapid sequence, using the same EARO for the same Address. Gaps
Gaps between the Address Registrations will invalidate some of the between the Address Registrations will invalidate some of the routes
routes till the Address Registration finally shows on those routes. till the Address Registration finally shows on those routes.
[RFC8505] introduces error Status values in the NA(EARO) which can be [RFC8505] introduces error Status values in the NA(EARO) which can be
received synchronously upon an NS(EARO) or asynchronously. The RUL received synchronously upon an NS(EARO) or asynchronously. The RUL
needs to support both cases and should refrain from using the address needs to support both cases and should refrain from using the address
when the Status Value indicates a rejection. when 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 2.1 of [USEofRPLinfo] defines the rules for tunneling either
to the final destination (e.g., a RUL) or to its attachment Router to the final destination (e.g., a RUL) or to its attachment Router
(designated as 6LR). To terminate the IP-in-IP tunnel, the RUL, as (designated as 6LR). To terminate the IP-in-IP tunnel, the RUL, as
an IPv6 Host, must be able to decapsulate the tunneled packet and an IPv6 Host, must be able to decapsulate the tunneled packet and
either drop the inner packet if it is not the final destination, or either drop the inner packet if it is not the final destination, or
pass it to the upper layer for further processing. Unless it is pass it to the upper layer for further processing. Unless it is
aware by other means that the RUL can handle IP-in-IP properly, which aware by other means that the RUL can handle IP-in-IP properly, which
skipping to change at page 12, line 18 skipping to change at page 12, line 31
prescribed by section 4.2 of [RFC8200]. An RPI with an Option Type prescribed by section 4.2 of [RFC8200]. An RPI with an Option Type
of 0x23 [USEofRPLinfo] is thus skipped when not recognized. of 0x23 [USEofRPLinfo] is thus skipped when not recognized.
5.4. Support of the Routing Header 5.4. Support of the Routing Header
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 Source
Routing Header with a Routing Type of 3 [RFC6554] is ignored when the Routing Header with a Routing Type of 3 [RFC6554] is ignored when the
Segments Left is zero, and the packet is dropped otherwise. Segments Left is zero, and the packet is dropped otherwise.
6. Updating 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 IP-in-IP encapsulation between the Conforming to [USEofRPLinfo], an IP-in-IP encapsulation between the
6LR and the RPL Root is used to carry the RPL artifacts and remove 6LR and the RPL Root is used to carry the RPL artifacts and 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 value of lifetime is used for both, and a
single keep-alive message, the RPL DAO, traverses the RPL network. A single keep-alive message, the RPL DAO, traverses the RPL network. A
new behavior is introduced whereby the RPL Root proxies the EDAR new behavior is introduced whereby the RPL Root proxies the EDAR
message to the 6LBR on behalf of the 6LR (more in Section 8), for any message to the 6LBR on behalf of the 6LR (more in Section 8), for any
Leaf node that implements the 6LN functionality in [RFC8505]. Leaf node that implements the 6LN functionality 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. Section 6.1 adds the capabilities to transport a destination prefix. This document adds the capabilities to
the ROVR field (see Section 4.2.3) and the full IPv6 Address of the transport the ROVR field (see Section 4.2.3) and the IPv6 Address of
prefix advertiser when the Target is a shorter prefix, signaled by a the prefix advertiser when the Target is a shorter prefix. Their use
new "F" flag. The position of the "F" flag is indicated in is signaled respectively by a new ROVR Size field being non-zero and
Section 12.4. a new "Advertiser address in Full" 'F' flag set, more in Section 6.1.
This specification defines the new "Root Proxies EDAR/EDAC" (P) flag This specification defines the new "Root Proxies EDAR/EDAC" (P) flag
and encodes it in one of these reserved flags of the the RPL DODAG and encodes it in one of these reserved flags of the RPL DODAG
Configuration option , more in Section 6.2. The position of the "P" Configuration option, more in Section 6.2.
flag is indicated in Section 12.3.
The RPL Status defined in section 6.5.1 of [RFC6550] for use in the The RPL Status defined in section 6.5.1 of [RFC6550] for use in the
DAO-ACK message is extended to be placed in DCO messages DAO-ACK message is extended to be placed in DCO messages
[EFFICIENT-NPDAO] as well. Furthermore, this specification enables [EFFICIENT-NPDAO] as well. Furthermore, this specification enables
to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO to carry the EARO Status defined for 6LoWPAN ND in RPL DAO and DCO
messages, embedded in a RPL Status, more in Section 6.3. messages, embedded in a RPL Status, more in Section 6.3.
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 Root to generate the proxied EDAR message to the 6LBR.
The new "F" flag is set to indicate that the Target Prefix field The new 'F' flag is set to indicate that the Target Prefix field
contains the address of the advertising node in full, in which case contains the IPv6 address of the advertising node, in which case the
the length of the Target Prefix field is 16 bytes regardless of the length of the Target Prefix field is 128 bits regardless of the value
value of the Prefix Length field. If the "F" flag is reset, the of the Prefix Length field. If the 'F' flag is reset, the Target
Target Prefix field MUST be aligned to the next byte boundary after Prefix field MUST be aligned to the next byte boundary after the size
the size (expressed in bits) indicated by the Prefix Length field. (expressed in bits) indicated by the Prefix Length field. Padding
Padding bits are reserved and set to 0 as prescribed by section 6.7.7 bits are reserved and set to 0 per section 6.7.7 of [RFC6550].
of [RFC6550].
With this specification the ROVR is the remainder of the RPL Target With this specification the ROVR is the remainder of the RPL Target
Option. The size of the ROVR is indicated in a new ROVR Size field Option. The size of the ROVR is indicated in a new ROVR Size field
that is encoded to map one-to-one with the Code Suffix in the EDAR that is encoded to map one-to-one with the Code Suffix in the EDAR
message (see table 4 of [RFC8505]). message (see table 4 of [RFC8505]). The ROVR Size field is taken
from the flags field, which is an update to the RPL Target Option
Flags IANA registry.
The modified format is illustrated in Figure 3. It is backward The updated format is illustrated in Figure 3. It is backward
compatible with the Target Option in [RFC6550] and SHOULD be used as compatible with the Target Option in [RFC6550]. It SHOULD be used as
a replacement in new implementations even for Storing Mode operations a replacement in new implementations in all MOPs in preparation for
in preparation for upcoming security mechanisms based in the ROVR. upcoming Route Ownership Validation mechanisms based on the ROVR,
unless the device 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 |ROVRsz |F|Flags| Prefix Length | | Type = 0x05 | Option Length |ROVRsz |F|Flags| Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Target Prefix (Variable Length) | | Target Prefix (Variable Length) |
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier (ROVR) ... ... Registration Ownership Verifier (ROVR) ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Updated Target Option Figure 3: Updated Target Option
New fields: New fields:
ROVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, or 4, ROVRsz (ROVR Size): Indicates the Size of the ROVR. It MAY be 1, 2,
denoting a ROVR size of 64, 128, 192, or 256 bits, respectively. 3, or 4, indicating a ROVR size of 64, 128, 192, or 256 bits,
respectively. A value if 0 thus denotes a legacy Target Option.
F: 1-bit flag. Set to indicate that Target Prefix field contains an F: 1-bit flag. Set to indicate that Target Prefix field contains an
Address of prefix advertiser in full. address of prefix advertiser in full.
Registration Ownership Verifier (ROVR): This is the same field as in Registration Ownership Verifier (ROVR): This is the same field as in
the EARO, see [RFC8505] the EARO, see [RFC8505]
6.2. Updated DODAG Configuration Option 6.2. New 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. As shown in Figure 4, the Option was originally designed with DODAG. As shown in Figure 4, the Option was originally designed with
4 bit positions reserved for future use as Flags. 4 bit positions 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| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
<- Flags -> <- Flags ->
Figure 4: DODAG Configuration Option (Partial View) Figure 4: 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 set to indicate support for this specification at the The 'P' bit is encoded in position 1 of the reserved Flags in the
Root within the DODAG. The "P" flag is encoded in position 1 of the DODAG Configuration Option (counting from bit 0 as the most
reserved Flags in the DODAG Configuration Option (counting from bit 0 significant bit) and set to 0 in legacy implementations as specified
as the most significant bit) and set to 0 in legacy implementations respectively in Sections 20.14 and 6.7.6 of [RFC6550].
as specified respectively in Sections 20.14 and 6.7.6 of [RFC6550].
The "P" flag is set to indicate that the Root performs the proxy The 'P' bit is set to indicate that the Root performs the proxy
operation, which implies that it supports the Updated RPL Target operation, which implies that it supports this specification and the
Option (see Section 6.1). updated RPL Target Option (see Section 6.1).
Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the
definition of the Flags applies to Mode of Operation (MOP) values definition of the Flags applies to Mode of Operation (MOP) values
zero (0) to six (6) only. For a MOP value of 7, the Root is expected zero (0) to six (6) only. For a MOP value of 7, the Root is expected
to perform the proxy operation by default. to perform the proxy operation by default.
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 "T" flag as set option". Therefore, a legacy parent propagates the T Flag as set by
by the Root, and when the "T" flag is set, it is transparently the Root, and when the T Flag is set, it is transparently flooded to
flooded to all the nodes in the DODAG. 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 and values are assigned as follows:
+---------+--------------------------------+ +---------+--------------------------------+
| Range | Meaning | | Range | Meaning |
+---------+--------------------------------+ +---------+--------------------------------+
| 0 | Success/Unqualified acceptance | | 0 | Success/Unqualified acceptance |
+---------+--------------------------------+ +---------+--------------------------------+
| 1-127 | Not an outright rejection | | 1-127 | Not an outright rejection |
+---------+--------------------------------+ +---------+--------------------------------+
| 128-255 | Rejection | | 128-255 | Rejection |
+---------+--------------------------------+ +---------+--------------------------------+
Table 1: RPL Status per RFC 6550 Table 1: RPL Status per RFC 6550
The 6LoWPAN ND Status was defined for use in the EARO and the The 6LoWPAN ND Status was defined for use in the EARO, see section
currently defined values are listed in table 1 of [RFC8505]. This 4.1 of [RFC8505]. This specification enables to carry the 6LoWPAN ND
specification enables to carry the 6LoWPAN ND Status values in RPL Status values in RPL DAO and DCO messages, embedded in the RPL Status
DAO and DCO messages, embedded in the RPL Status field. field.
To achieve this, Section 12.2 reduces the range of the EARO Status To achieve this, the range of the EARO Status values is reduced to
values to 0-63 to ensure that they fit within a RPL Status as shown 0-63, which updates the IANA registry created for [RFC6775]. This
in Figure 5. reduction ensures that the values fit within a RPL Status as shown in
Figure 5. See Section 12.2, Section 12.5, and Section 12.6 for the
respective IANA declarations.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|A| Value | |E|A|StatusValue|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 5: RPL Status Format Figure 5: RPL Status Format
The following RPL Status subfields are defined: This specification updates the RPL Status with subfields as indicated
below:
E: 1-bit flag. Set to indicate a rejection. When not set, a value E: 1-bit flag. Set to indicate a rejection. When not set, a Status
of 0 indicates Success/Unqualified acceptance and other values Value of 0 indicates Success/Unqualified acceptance and other
indicate "not an outright rejection" as per RFC 6550. values indicate "not an outright rejection" as per RFC 6550.
A: 1-bit flag. Indicates the type of the Status Value. A: 1-bit flag. Indicates the type of the RPL Status Value.
Status Value: 6-bit unsigned integer. If the 'A' flag is set this Status Value: 6-bit unsigned integer. If the 'A' flag is set this
field transports a Status Value defined for IPv6 ND EARO. When field transports a Status Value defined for IPv6 ND EARO. When
the 'A' flag is not set, the Status Value is defined for RPL. the 'A' flag is not set, the Status Value is 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 a EDAC
message, the RPL Root MUST copy the 6LoWPAN ND Status unchanged in message, the RPL Root MUST copy the 6LoWPAN ND Status Code unchanged
the RPL Status and set the 'A' bit. The RPL Root MUST set the 'E' in the RPL Status Value and set the 'A' flag. The RPL Root MUST set
flag for Values in range 1-10 which are all considered rejections. the 'E' flag for all rejection and unknown Status Codes. The Status
Codes in range 1-10 [RFC8505] are all considered rejections.
Reciprocally, upon a DCO or a DAO-ACK message from the RPL Root with Reciprocally, upon a DCO or a DAO-ACK message from the RPL Root with
a RPL Status that has the 'A' bit set, the 6LR MUST copy the RPL a RPL Status that has the 'A' flag set, the 6LR MUST copy the RPL
Status Value unchanged in the Status field of the EARO when Status Value unchanged in the Status field of the EARO when
generating an NA to the RUL. generating an NA to the RUL.
7. Updating draft-ietf-roll-efficient-npdao 7. Enhancements to draft-ietf-roll-efficient-npdao
[EFFICIENT-NPDAO] defines the DCO for RPL Storing Mode only, with a [EFFICIENT-NPDAO] defines the DCO message for RPL Storing Mode only,
link-local scope. This specification extends its use to the Non- with a link-local scope. All nodes in the RPL network are expected
Storing MOP, whereby the DCO is sent unicast by the Root directly to to support the specification since the message in processed hop by
the RAN that injected the DAO message for the considered target. hop along the path this is being cleaned up.
This specification leverages the DCO between the Root and the 6LR This specification extends the use of the DCO message to the Non-
that serves as attachment Router for a RUL. 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.
In that case, intermediate nodes do not need to support
[EFFICIENT-NPDAO]; they forward the DCO message as a plain IPv6
packet between the Root and the RAN.
8. Updating RFC 8505 This specification leverages the Non-Storing DCO between the Root and
the 6LR that serves as attachment Router for a RUL. A 6LR and a Root
that support this specification MUST implement the Non-Storing DCO.
This document updates [RFC8505] to change the behavior of a RPL 8. Enhancements to RFC 6775 and RFC8505
Router acting as 6LR and of a RUL acting as 6LN in the 6LoWPAN ND
Address Registration. If the RPL Root advertise the capability to This document updates [RFC6775] and [RFC8505] to reduce the range of
proxy the EDAR/EDAC exchange to the 6LBR, the 6LR refrains from the ND Status Codes down to 64 values.
sending the keep-alive EDAR message. Instead, if it is separated
from the 6LBR, the Root regenerates the EDAR message to the 6LBR This document also changes the behavior of a 6LR acting as RPL Router
periodically, upon a DAO message that signals the liveliness of the and of a 6LN acting as RUL in the 6LoWPAN ND Address Registration as
Address. follows:
* If the RPL Root advertises the capability to proxy the EDAR/EDAC
exchange to the 6LBR, the 6LR refrains from sending the keep-alive
EDAR message. If it is separated from the 6LBR, the Root
regenerates the EDAR message to the 6LBR periodically, upon a DAO
message that signals the liveliness of the address.
* The use of the R Flag is extended to the NA(EARO) to confirm
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' bit in the
DODAG Configuration Option and performs the EDAR proxy operation. DODAG Configuration Option and performs the EDAR proxy operation.
If the "P" flag is reset, the 6LR MUST generate the periodic EDAR If the 'P' bit is reset, the 6LR MUST generate the periodic EDAR
messages and process the returned status as specified in [RFC8505]. messages and process the returned status as specified in [RFC8505].
If the EDAC indicates success, the rest of the flow takes place as If the EDAC indicates success, the rest of the flow takes place as
presented but without the proxied EDAR/EDAC exchange. presented but without the proxied EDAR/EDAC exchange.
Section 9.1 provides an overview of the route injection in RPL,
whereas Section 9.2 offers more details from the perspective of the
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
Extended Duplicate Address messages, EDAR and EDAC, all the way from Extended Duplicate Address messages, EDAR and EDAC, all the way from
a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange
with the 6LBR is proxied by the RPL Root upon the DAO message that with the 6LBR is proxied by the RPL Root upon the DAO message that
refreshes the RPL routing state. The first EDAR upon a new refreshes the RPL routing state. The first EDAR upon a new
Registration cannot be proxied, though, as it serves for the purpose Registration cannot be proxied, though, as it serves for the purpose
of DAD, which must be verified before the address is injected in RPL. of DAD, which must be verified before the address is injected in RPL.
In a RPL network where the function is enabled, refreshing the state In a RPL network where the function is enabled, refreshing the state
in the 6LBR is the responsibility of the Root. Consequently, only in the 6LBR is the responsibility of the Root. Consequently, only
addresses that are injected in RPL will be kept alive at the 6LBR by addresses that are injected in RPL will be kept alive at the 6LBR by
the RPL Root. the RPL Root. Since RULs are advertised using Non-Storing Mode, the
DAO message flow and the keep alive EDAR/EDAC can be nested within
Since RULs are advertised using Non-Storing Mode, the DAO message the Address (re)Registration flow. Figure 6 illustrates that, for
flow and the keep alive EDAR/EDAC can be nested within the Address the first Registration, both the DAD and the keep-alive EDAR/EDAC
(re)Registration flow. Figure 6 illustrates that for the first exchanges happen in the same sequence.
Registration, both the DAD and the keep-alive EDAR/EDAC exchanges
happen in the same sequence.
6LN/RUL 6LR Root 6LBR 6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | Extended DAR | | | Extended DAR |
| |--------------------------------->| | |--------------------------------->|
| | | | | |
| | Extended DAC | | | Extended DAC |
| |<---------------------------------| | |<---------------------------------|
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
Figure 6: First RUL Registration Flow Figure 6: First RUL Registration Flow
To achieve this, the lifetimes and sequence counters in 6LoWPAN ND This flow requires that the lifetimes and sequence counters in
and RPL are aligned. In other words, the Path Sequence and the Path 6LoWPAN ND and RPL are aligned.
Lifetime in the DAO message are taken from the Transaction ID and the
Address Registration lifetime in the NS(EARO) message from the 6LN. ITo achieve this, the Path Sequence and the Path Lifetime in the DAO
message are taken from the Transaction ID and the Address
Registration lifetime in the NS(EARO) message from the 6LN.
On the first Address Registration, illustrated in Figure 6 for RPL On the first Address Registration, illustrated in Figure 6 for RPL
Non-Storing Mode, the Extended Duplicate Address exchange takes place Non-Storing Mode, the Extended Duplicate Address exchange takes place
as prescribed by [RFC8505]. If the exchange fails, the 6LR returns as prescribed by [RFC8505]. If the exchange fails, the 6LR returns
an NA message with a negative status to the 6LN, the NCE is not an NA message with a negative status to the 6LN, the NCE is not
created and the address is not injected in RPL. If it is successful, created, and the address is not injected in RPL. Otherwise, the 6LR
the 6LR creates an NCE and injects the Registered Address in the RPL creates an NCE and injects the Registered Address in the RPL routing
routing using a DAO/DAO-ACK exchange with the RPL DODAG Root. using a DAO/DAO-ACK exchange with the RPL DODAG Root.
An issue may be detected later, e.g., the address moves within the
LLN or to a different Root on a backbone [6BBR]. In that case the
value of the status that indicates the issue can be passed from
6LoWPAN ND to RPL and back as illustrated in Figure 7.
6LN/RUL 6LR Root 6LBR
| | | |
| | | NA(EARO, Status) |
| | |<-----------------|
| | DCO(Status) | |
| |<------------| |
| NA(EARO, Status) | | |
|<-----------------| | |
| | | |
Figure 7: Asynchronous Issue
An Address re-Registration is performed by the 6LN to maintain the An Address Registration refresh is performed by the 6LN to maintain
NCE in the 6LR alive before lifetime expires. Upon the refresh of an the NCE in the 6LR alive before the lifetime expires. Upon the
Address re-Registration, as illustrated in Figure 8, the 6LR injects refresh of a registration, the 6LR reinjects the corresponding route
the Registered Address in RPL. in RPL before it expires, as illustrated in Figure 7.
6LN/RUL 6LR Root 6LBR 6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| | |
| | DAO | | | | DAO | |
| |------------->| | | |------------->| |
| | | EDAR | | | | EDAR |
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 8: Next RUL Registration Flow Figure 7: Next RUL Registration Flow
This is what causes the RPL Root to refresh the state in the 6LBR, This is what causes the RPL Root to refresh the state in the 6LBR,
using an EDAC message. In case of an error in the proxied EDAR flow, using an EDAC message. In case of an error in the proxied EDAR flow,
the error is returned in the DAO-ACK using a RPL Status with the 'A' the error is returned in the DAO-ACK using a RPL Status with the 'A'
flag set that imbeds a 6LoWPAN Status Value as discussed in flag set that imbeds a 6LoWPAN Status Value as discussed in
Section 6.3. Section 6.3.
The 6LR may receive a requested DAO-ACK after it received an The 6LR may receive a requested DAO-ACK after it received an
asynchronous DCO, but the negative Status in the DCO supersedes a asynchronous DCO, but the negative Status in the DCO supersedes a
positive Status in the DAO-ACK regardless of the order in which they positive Status in the DAO-ACK regardless of the order in which they
are received. Upon the DAO-ACK - or the DCO if one arrives first - are received. Upon the DAO-ACK - or the DCO if one arrives first -
the 6LR responds to the RUL with an NA(EARO). the 6LR responds to the RUL with an NA(EARO).
The RUL MAY terminate the registration at any time by using a An issue may be detected later, e.g., the address moves to a
different DODAG with the 6LBR attached to a different 6LoWPAN
Backbone Router (6BBR), see Figure 5 in section 3.3 of [6BBR]. The
6BBR may send a negative ND status, e.g., in an asynchronous NA(EARO)
to the 6LBR.
[6BBR] expects that the 6LBR is collocated with the RPL Root, but if
not, the 6LBR MUST forward the Status Code to the originator of the
EDAR, either the 6LR or the RPL Root that proxies for it. The ND
Status Code is mapped in a RPL Status Value by the RPL Root, and then
back by the 6LR.
Figure 8 illustrates this in the case where the 6LBR and the Root are
not collocated, and the Root proxies the EDAR messages.
6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR <-ND-> 6BBR
| | | | |
| | | | NA(EARO) |
| | | |<------------|
| | | EDAC | |
| | |<-------------| |
| | DCO | | |
| |<------------| | |
| NA(EARO) | | | |
|<-------------| | | |
| | | | |
Figure 8: Asynchronous Issue
If the Root does not proxy, then the EDAC with a negative status
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
status back to the RUL in a NA(EARO) with the R Flag not set.
The RUL may terminate the registration at any time by using a
Registration Lifetime of 0. This specification requires that the RPL Registration Lifetime of 0. This specification requires that the RPL
Target Option transports the ROVR. This way, the same flow as the Target Option transports the ROVR. This way, the same flow as the
heartbeat flow is sufficient to inform the 6LBR using the Root as heartbeat flow is sufficient to inform the 6LBR using the Root as
proxy as illustrated in Figure 8. proxy, as illustrated in Figure 7.
Any combination of the logical functions of 6LR, Root and 6LBR might Any combination of the logical functions of 6LR, Root, and 6LBR might
be collapsed in a single node. be collapsed in a single node.
9.2. Detailed Operation 9.2. Detailed Operation
9.2.1. Perspective of the RUL Acting as 6LN 9.2.1. Perspective of the 6LN Acting as RUL
This specification does not alter the operation of a 6LoWPAN ND- This specification does not alter the operation of a 6LoWPAN ND-
compliant 6LN, and a RUL is expected to operate as follows: compliant 6LN/RUL, which is expected to operate as follows:
1. The 6LN obtains an IPv6 global address, either using Stateless 1. The 6LN obtains an IPv6 global address, either using Stateless
Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix
Information Option (PIO) [RFC4861] found in an RA message, or Information Option (PIO) [RFC4861] found in an RA message, or
some other means such as DHCPv6 [RFC3315]. some other means, such as DHCPv6 [RFC8415].
2. Once it has formed an address, the 6LN (re)registers its address 2. Once it has formed an address, the 6LN registers its address and
periodically, within the Lifetime of the previous Address refreshes its registration periodically, early enough within the
Registration, as prescribed by [RFC6775], to refresh the NCE Lifetime of the previous Address Registration, as prescribed by
before the lifetime indicated in the EARO expires. It MUST set [RFC6775], to refresh the NCE before the lifetime indicated in
the "T" flag and the TID is incremented each time and wraps in a the EARO expires. It MUST set the T Flag. The TID is
lollipop fashion (see section 5.2.1 of [RFC8505] which is fully incremented each time and wraps in a lollipop fashion (see
compatible with section 7.2 of [RFC6550]). section 5.2.1 of [RFC8505], which is fully compatible with
section 7.2 of [RFC6550]).
3. As stated in section 5.2 of [RFC8505], the 6LN can register to 3. As stated in section 5.2 of [RFC8505], the 6LN can register to
more than one 6LR at the same time. In that case, it uses the more than one 6LR at the same time. In that case, it uses the
same EARO for all of the parallel Address Registrations. The 6LN same EARO for all of the parallel Address Registrations, with the
SHOULD send the registration(s) that have a non-zero Registration exception of the Registration Lifetime field and the setting of
Lifetime and ensure that one succeeds before it terminates other the R flag that may differ. The 6LN SHOULD send the NS(EARO), if
registrations, to maintain the state in the network and at the any, that maintain a registration active (i.e., with a non-zero
6LBR and minimize the churn. Registration Lifetime) and ensure that one succeeds before it
sends an NS(EARO) that terminates another registration, to avoid
the churn related to transient route invalidation in the RPL
network.
4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets 4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets
the "R" flag in the EARO of at least one registration, whereas the R Flag in the EARO of its registration(s) for which it
acting as a RAN it never does. If the "R" flag is not echoed in requires routing services. If the R Flag is not echoed in the
the NA, the RUL SHOULD attempt to use another 6LR. The RUL NA, the RUL SHOULD attempt to use another 6LR. The RUL SHOULD
SHOULD send the registration(s) with the "R" flag set and ensure send the registration(s) with the R Flag set and ensure that one
that one succeeds before it sends the registrations with the flag succeeds before it sends the registrations with the flag reset.
reset. In case of a conflict with the preceeding rule on In case of a conflict with the preceding rule on lifetime, the
lifetime, the rule on lifetime has precedence. rule on lifetime has precedence.
5. The 6LN may use any of the 6LRs to which it registered as default 5. The 6LN may use any of the 6LRs to which it registered as the
gateway. Using a 6LR to which the 6LN is not registered may default gateway. Using a 6LR to which the 6LN is not registered
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) so it is NOT RECOMMENDED. Validation function (SAVI) [RFC7039] so it is not recommended.
Even without support for RPL, a RUL may be aware of opaque values to Even without support for RPL, the RUL may be configured with an
be provided to the routing protocol. If the RUL has a knowledge of opaque value to be provided to the routing protocol. If the RUL has
the RPL Instance the packet should be injected into, then it SHOULD knowledge of the RPL Instance the packet should be injected into,
set the Opaque field in the EARO to the RPLInstanceID, else it MUST then it SHOULD set the Opaque field in the EARO to the RPLInstanceID,
leave the Opaque field to zero. else it MUST leave the Opaque field to zero.
Regardless of the setting of the Opaque field, the 6LN MUST set the Regardless of the setting of the Opaque field, the 6LN MUST set the
"I" field to zero to signal "topological information to be passed to "I" field to zero to signal "topological information to be passed to
a routing process" as specified in section 5.1 of [RFC8505]. a routing process", as specified in section 5.1 of [RFC8505].
A RUL is not expected to produce RPL artifacts in the data packets, A RUL is not expected to produce RPL artifacts in the data packets,
but it MAY do so. For instance, if the RUL has a minimal awareness but it may do so. For instance, if the RUL has minimal awareness of
of the RPL Instance then it can build an RPI. A RUL that places an the RPL Instance then it can build an RPI. A RUL that places an RPI
RPI in a data packet MUST indicate the RPLInstanceID of the RPL in a data packet MUST indicate the RPLInstanceID of the RPL Instance
Instance where the packet should be forwarded. All the flags and the where the packet should be forwarded. All the flags and the Rank
Rank field are set to zero as specified by section 11.2 of [RFC6550]. field are set to zero as specified by section 11.2 of [RFC6550].
9.2.2. Perspective of the Border Router Acting as 6LR 9.2.2. Perspective of the 6LR Acting as Border Router
Also as prescribed by [RFC8505], the 6LR generates an EDAR message As prescribed by [RFC8505], the 6LR generates an EDAR message upon
upon reception of a valid NS(EARO) message for the registration of a reception of a valid NS(EARO) message for the registration of a new
new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange IPv6 address by a 6LN. If the initial EDAR/EDAC exchange succeeds,
succeeds, then the 6LR installs an NCE for the Registration Lifetime. then the 6LR installs an NCE for the Registration Lifetime. For the
For the registration refreshes, if the RPL Root has indicated that it registration refreshes, if the RPL Root has indicated that it proxies
proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see the keep-alive EDAR/EDAC exchange with the 6LBR (see Section 6), the
Section 6), the 6LR MUST refrain from sending the keep-alive EDAR. 6LR MUST refrain from sending the keep-alive EDAR.
If the "R" flag is set in the NS(EARO), the 6LR MUST inject the Host If the R Flag is set in the NS(EARO), the 6LR SHOULD inject the Host
route in RPL, unless this is barred for other reasons, such as the route in RPL, unless this is barred for other reasons, such as the
saturation of the RPL parents. The 6LR MUST use a RPL Non-Storing saturation of the RPL parents. The 6LR MUST use a RPL Non-Storing
Mode signaling and the updated Target Option (see Section 6.1). The Mode signaling and the updated Target Option (see Section 6.1). The
6LR MUST request a DAO-ACK by setting the 'K' flag in the DAO 6LR MUST request a DAO-ACK by setting the 'K' flag in the DAO
message. Success injecting the route to the RUL is indicated by the message. Success injecting the route to the RUL's address is
'E' flag set to 0 in the RPL status of the DAO-ACK message. indicated by the 'E' flag set to 0 in the RPL status of the DAO-ACK
message.
The Opaque field in the EARO hints the 6LR on the RPL Instance that The Opaque field in the EARO provides a mean to signal which RPL
SHOULD be used for the DAO advertisements, and for the forwarding of Instance is to be used for the DAO advertisements and the forwarding
packets sourced at the registered address when there is no RPI in the of packets sourced at the Registered Address when there is no RPI in
packet, in which case the 6LR MUST encapsulate the packet to the Root the packet.
adding an RPI in the outer header. If the Opaque field is zero, the
6LR is free to use the default RPL Instance (zero) for the registered
address or to select an Instance of its choice.
If the "I" field is not zero, then the 6LR MUST consider that the As described in [RFC8505], if the "I" field is zero, then the Opaque
Opaque field is zero. If the Opaque field is not zero, then it is field is expected to carry the RPLInstanceID suggested by the 6LN;
expected to carry a RPLInstanceID for the RPL Instance suggested by otherwise, there is no suggested Instance. If the 6LR participates
the 6LN. If the 6LR does not participate to the associated Instance, in the suggested RPL Instance, then the 6LR MUST use that RPL
then the 6LR MUST consider that the Opaque field is zero; else, that Instance for the Registered Address.
is if the 6LR participates to the suggested RPL Instance, then the
6LR SHOULD use that Instance for the Registered Address. If there is no suggested RPL Instance or else if the 6LR does not
participate to the suggested Instance, it is expected that the
packets coming from the 6LN "can unambiguously be associated to at
least one RPL Instance" [RFC6550] by the 6LR.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is signaled as Target Prefix in the 1. The Registered Address is signaled as 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. The ROVR field is copied unchanged from the EARO set to 128 but the 'F' flag is not set since the advertiser is
not the RUL. The ROVR field is copied unchanged from the EARO
(see Section 6.1). (see Section 6.1).
2. The 6LR indicates one of its global or unique-local IPv6 unicast 2. The 6LR indicates one of its global or unique-local IPv6 unicast
addresses as the Parent Address in the RPL Transit Information addresses as the Parent Address in the RPL Transit Information
Option (TIO) associated with the Target Option Option (TIO) associated with the Target Option
3. The 6LR sets the External 'E' flag in the TIO to indicate that it 3. The 6LR sets the External 'E' flag in the TIO to indicate that it
redistributes an external target into the RPL network is redistributing an external target into the RPL network
4. the Path Lifetime in the TIO is computed from the Lifetime in the 4. the Path Lifetime in the TIO is computed from the Registration
EARO Option. This adapts it to the Lifetime Units used in the Lifetime in the EARO. This operation converts seconds to the
RPL operation; note that if the lifetime is 0, then the DAO Lifetime Units used in the RPL operation. This creates the
message is a No-Path DAO that cleans up the the routes down to deployment constraint that the Lifetime Unit is reasonably
the RUL; this also causes the Root as a proxy to send an EDAR compatible with the expression of the Registration Lifetime.
message to the 6LBR with a Lifetime of 0. e.g., a Lifetime Unit of 0x4000 maps the most significant byte of
the Registration Lifetime to the Path Lifetime.
In that operation, the Path Lifetime must be rounded, if needed,
to the upper value to ensure that the path has a longer lifetime
than the registration.
Note that if the Registration Lifetime is 0, then the Path
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
causes the Root as a proxy to send an EDAR message to the 6LBR
with a Lifetime of 0.
5. the Path Sequence in the TIO is set to the TID value found in the 5. the Path Sequence in the TIO is set to the TID value found in the
EARO option. EARO option.
Upon receiving the DAO-ACK or an asynchronous DCO message, the 6LR Upon receiving or timing out the DAO-ACK after an implementation-
MUST send the NA(EARO) to the RUL. specific number of retries, the 6LR MUST send the corresponding
NA(EARO) to the RUL. Upon receiving an asynchronous DCO message, if
a DAO-ACK is pending then the 6LR MUST wait for the DAO-ACK to send
the NA(EARO) and deliver the status found in the DCO, else it MUST
send an asynchronous NA(EARO) to the RUL immediately.
The 6LR MUST set "R" flag in the NA(EARO) back if and only if the 'E' The 6LR MUST set the R Flag in the NA(EARO) back if and only if the
flag is reset, indicating that the 6LR injected the Registered 'E' flag is reset, indicating that the 6LR injected the Registered
Address in the RPL routing successfully and that the EDAR proxy Address in the RPL routing successfully and that the EDAR proxy
operation succeeded. operation succeeded.
If the 'A' flag in the RPL Status is set, the embedded Status Value If the 'A' flag in the RPL Status is set, the embedded Status Value
is passed back to the RUL in the EARO Status. If the 'E' flags is is passed back to the RUL in the EARO Status. If the 'E' flag is
also set, the registration failed for 6LoWPAN ND related reasons, and also set, the registration failed for 6LoWPAN ND related reasons, and
the NCE is removed. the NCE is removed.
An error injecting the route causes the 'E' flag to be set. If the
error is not related to ND, the 'A' flag is not set. In that case,
the registration succeeds, but the RPL route is not installed. So
the NA(EARO) is returned with a positive status but the R Flag not
set, which means that the 6LN obtained a binding but no route.
If the 'A' flag is not set in the RPL Status of the DAO-ACK, then the If the 'A' flag is not set in the RPL Status of the DAO-ACK, then the
6LoWPAN ND operation succeeded and an EARO Status of 0 (Success) MUST 6LoWPAN ND operation succeeded, and an EARO Status of 0 (Success)
be returned to the RUL, even if the 'E' flag is set in the RPL MUST be returned to the 6LN. The EARO Status of 0 MUST also be used
Status. The EARO Status of 0 MUST also be used if the 6LR could not if the 6LR did not attempt to inject the route but could create the
even try to inject the route. binding after a successful EDAR/EDAC exchange or refresh it.
This means that, in case of an error injecting the route that is not If the 'E' flag is set in the RPL Status of the DAO-ACK, then the
related to ND, the registration succeeds but the RPL route is not route was not installed and the R flag MUST NOT be set in the
installed, which is signaled by the "R" flag reset. It is up to the NA(EARO). The R flag MUST NOT be set if the 6LR did not attempt to
6LN to keep the binding with the 6LR or destroy it. 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 indicating transporting an enabled, in case of a DAO-ACK or a DCO indicating transporting an
EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge
the 6LN for ownership of the address, as described in section 6.1 of the 6LN for ownership of the address, as described in section 6.1 of
[AP-ND], before the Registration is complete. This ensures that the [AP-ND], before the Registration is complete. This flow, illustrated
address is validated before it is injected in the RPL routing. in Figure 9, ensures that the address is validated before it is
injected in the RPL routing.
If the challenge succeeds then the operations continue as normal. In If the challenge succeeds, then the operations continue as normal.
particular a DAO message is generated upon the NS(EARO) that proves In particular, a DAO message is generated upon the NS(EARO) that
the ownership of the address. If the challenge failed, the 6LR proves the ownership of the address. If the challenge failed, the
rejects the registration as prescribed by AP-ND and may take actions 6LR rejects the registration as prescribed by AP-ND and may take
to protect itself against DoS attacks by a rogue 6LN, see Section 11. actions to protect itself against DoS attacks by a rogue 6LN, see
Section 11.
6LN 6LR Root 6LBR
| | | |
|<--------------- RA ---------------------| | |
| | | |
|------ NS EARO (ROVR=Crypto-ID) -------->| | |
| | | |
|<- NA EARO(status=Validation Requested) -| | |
| | | |
|----- NS EARO and Proof-of-ownership -->| |
| |--------- EDAR ------->|
| | |
| |<-------- EDAC --------|
| | |
| | | |
| |-- DAO --->| |
| | |-- EDAR -->|
| | | |
| | |<-- EDAC --|
| |<- DAO-ACK-| |
| | | |
|<----------- NA EARO (status=0)----------| | |
| | | |
...
| | | |
|------ NS EARO (ROVR=Crypto-ID) -------->| | |
| |-- DAO --->| |
| | |-- EDAR -->|
| | | |
| | |<-- EDAC --|
| |<- DAO-ACK-| |
|<----------- NA EARO (status=0)----------| | |
| | | |
...
Figure 9: Address Protection
The 6LR may at any time send a unicast asynchronous NA(EARO) with the The 6LR may at any time send a unicast asynchronous NA(EARO) with the
"R" flag reset to signal that it stops providing routing services, R Flag reset to signal that it stops providing routing services, and/
and/or with the EARO Status 2 "Neighbor Cache full" to signal that it or with the EARO Status 2 "Neighbor Cache full" to signal that it
removes the NCE. It may also send a final RA, unicast or multicast, removes the NCE. It may also send a final RA, unicast or multicast,
with a Router Lifetime field of zero, to signal that it stops serving with a Router Lifetime field of zero, to signal that it stops serving
as Router, as specified in section 6.2.5 of [RFC4861]. as Router, as specified in section 6.2.5 of [RFC4861]. This may
happen upon a DCO or a DAO-ACK message indicating the path is already
removed; else the 6LR SHOULD remove the Host route to the 6LN using a
DAO message with a Path Lifetime of zero.
If a 6LR receives a valid NS(EARO) message with the "R" flag reset A valid NS(EARO) message with the R Flag not set and a Registration
and a Registration Lifetime that is not 0, and the 6LR was injecting Lifetime that is not zero signals that the 6LN wishes to maintain the
the Registered Address due to previous NS(EARO) messages with the "R" binding but does not require the routing services from the 6LR (any
flag set, then the 6LR MUST stop injecting the address. It is up to more). Upon this message, if, due to previous NS(EARO) with the R
the Registering 6LN to maintain the corresponding route from then on, Flag set, the 6LR was injecting the Host route to the Registered
either keeping it active via a different 6LR or by acting as a RAN Address in RPL using DAO messages, then the 6LR MUST invalidate the
and managing its own reachability. Host route in RPL using a DAO with a Path Lifetime of zero. It is up
to the Registering 6LN to maintain the corresponding route from then
on, either keeping it active via a different 6LR or by acting as a
RAN and managing its own reachability.
9.2.3. Perspective of the RPL Root 9.2.3. Perspective of the RPL Root
A RPL Root SHOULD set the "P" flag in the RPL DODAG Configuration A RPL Root MUST set the 'P' bit in the RPL DODAG Configuration Option
Option of the DIO messages that it generates (see Section 6) to of the DIO messages that it generates (see Section 6) to signal that
signal that it proxies the EDAR/EDAC exchange and supports the it proxies the EDAR/EDAC exchange and supports the Updated RPL Target
Updated RPL Target option. The remainder of this section assumes option.
that it does.
Upon reception of a DAO message, for each updated RPL Target Option Upon reception of a DAO message, for each updated RPL Target Option
(see Section 6.1) that creates or updates an existing RPL state, the (see Section 6.1) that creates or updates an existing RPL state, the
Root MUST notify the 6LBR. This can be done using an internal API if Root MUST notify the 6LBR by using a proxied EDAR/EDAC exchange. If
they are integrated, or using a proxied EDAR/EDAC exchange if they if the RPL Root and the 6LBR are integrated, an internal API can be
are separate entities. used.
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;
skipping to change at page 23, line 43 skipping to change at page 27, line 5
Table 4 of [RFC8505] depending on the size of the ROVR field. Table 4 of [RFC8505] depending on the size of the ROVR field.
Upon receiving an EDAC message from the 6LBR, if a DAO is pending, Upon receiving an EDAC message from the 6LBR, if a DAO is pending,
then the Root MUST send a DAO-ACK back to the 6LR. Else, if the then the Root MUST send a DAO-ACK back to the 6LR. Else, if the
Status in the EDAC message is not "Success", then it MUST send an Status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. asynchronous DCO to the 6LR.
In either case, the EDAC Status is embedded in the RPL Status with In either case, the EDAC Status is embedded in the RPL Status with
the 'A' flag set. the 'A' flag set.
The proxied EDAR/EDAC exchange MUST be protected with a timer of an
appropriate duration and a number of retries, that are
implementation-dependent, and SHOULD be configurable since the Root
and the 6LBR are typically nodes with a higher capacity and
manageability than 6LRs. Upon timing out, the Root MUST send an
error back to the 6LR as above, either using a DAO-ACK or a DCO, as
appropriate, with the 'A' and 'E' flags set in the RPL status, and a
RPL Status Value of 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 Root is not the new attachment 6LR
of the RUL, so it is not impacted by this specification. of the RUL, so it is not impacted by this specification.
Upon reception of an EDAR message, the 6LBR acts as prescribed by Upon reception of an EDAR message, the 6LBR acts as prescribed by
[RFC8505] and returns an EDAC message to the sender. [RFC8505] and returns an EDAC message to the sender.
10. Protocol Operations for Multicast Addresses 10. Protocol Operations for Multicast Addresses
Section 12 of [RFC6550] details the RPL support for multicast flows. Section 12 of [RFC6550] details the RPL support for multicast flows.
This support is not source-specific and only operates as an extension This support is not source-specific and only operates as an extension
to the Storing Mode of Operation for unicast packets. Note that it to the Storing Mode of Operation for unicast packets. Note that it
is the RPL model that the multicast packet is passed as a Layer-2 is the RPL model that the multicast packet is passed as a Layer-2
unicast to each of the interested children. This remains true when unicast to each of the interested children. This remains true when
forwarding between the 6LR and the listener 6LN. forwarding between the 6LR and the listener 6LN.
"Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its "Multicast Listener Discovery Version 2 (MLDv2) for IPv6" [RFC3810]
updated version "Multicast Listener Discovery Version 2 (MLDv2) for provide an interface for a listener to register to multicast flows.
IPv6" [RFC3810] provide an interface for a listener to register to In the MLD model, the Router is a "querier", and the Host is a
multicast flows. MLDv2 is backwards compatible with MLD, and adds in multicast listener that registers to the querier to obtain copies of
particular the capability to filter the sources via black lists and the particular flows it is interested in.
white lists. In the MLD model, the Router is a "querier" and the
Host is a multicast listener that registers to the querier to obtain
copies of the particular flows it is interested in.
On the first Address Registration, as illustrated in Figure 9, the
6LN, as an MLD listener, sends an unsolicited Report to the 6LR in
order to start receiving the flow immediately.
6LN/RUL 6LR Root 6LBR
| | | |
| unsolicited Report | | |
|------------------->| | |
| <L2 ack> | | |
| | DAO | |
| |-------------->| |
| | DAO-ACK | |
| |<--------------| |
| | | <if not listening> |
| | | unsolicited Report |
| | |------------------->|
| | | |
Figure 9: First Multicast Registration Flow The equivalent of the first Address Registration happens as
illustrated in Figure 10. The 6LN, as an MLD listener, sends an
unsolicited Report to the 6LR. This enables it to start receiving
the flow immediately, and causes the 6LR to inject the multicast
route in RPL.
Since multicast Layer-2 messages are avoided, it is important that This specification does not change MLD but will operate more
the asynchronous messages for unsolicited Report and Done are sent efficiently if the asynchronous messages for unsolicited Report and
reliably, for instance using a Layer-2 acknowledgment, or attempted Done are sent by the 6LN as Layer-2 unicast to the 6LR, in particular
multiple times. on wireless.
The 6LR acts as a generic MLD querier and generates a DAO for the The 6LR acts as a generic MLD querier and generates a DAO with the
multicast target. The lifetime of the DAO is set to be in the order Multicast Address as the Target Prefix as described in section 12 of
of the Query Interval, yet larger to account for variable propagation [RFC6550]. As for the Unicast Host routes, the Path Lifetime
delays. 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 The Root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the as the querier, so as to get packets from a source external to the
RPL domain. RPL domain.
Upon a DAO with a multicast target, the RPL Root checks if it is Upon a DAO with a Target option for a multicast address, the RPL Root
already registered as a listener for that address, and if not, it checks if it is already registered as a listener for that address,
performs its own unsolicited Report for the multicast target. and if not, it performs its own unsolicited Report for the multicast
address as sescribed in section 5.1 of [RFC3810]. The report is
source independent, so there is no Source Address listed.
An Address re-Registration is pulled periodically by 6LR acting as 6LN/RUL 6LR Root 6LBR
querier. Note that the message may be sent unicast to all the known | | | |
individual listeners. | unsolicited Report | | |
|------------------->| | |
| <L2 ack> | | |
| | DAO | |
| |-------------->| |
| | DAO-ACK | |
| |<--------------| |
| | | <if not done already> |
| | | unsolicited Report |
| | |---------------------->|
| | | |
Upon the timing out of the Query Interval, the 6LR sends a Query to Figure 10: First Multicast Registration Flow
each of its listeners, and gets a Report back that is mapped into a
DAO, as illustrated in Figure 10: The equivalent of the registration refresh is pulled periodically by
the 6LR acting as querier. Upon the timing out of the Query
Interval, the 6LR sends a Multicast Address Specific Query to each of
its listeners, for each Multicast Address, and gets a Report back
that is mapped into a DAO one by one. Optionally, the 6LR MAY send a
General Query, where the Multicast Address field is set to zero. 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
there are Multicast Address Records in the Report message, copying
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
of the 6LR's parents.
Asynchronously to this, a similar procedure happens between the Root
and a router such as the 6LBR that serves multicast flows on the Link
where the Root is located. Again the Query and Report messages are
source independent. The Root lists exactly once each Multicast
Address for which it has at least one active multicast DAO state,
copying the multicast address in the DAO state in the Multicast
Address field of the Multicast Address Records in the Report message.
This is illustrated in Figure 11:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | |
Figure 10: Next Registration Flow Figure 11: Next Registration Flow
Note that any of the functions 6LR, Root and 6LBR might be collapsed Note that any of the functions 6LR, Root and 6LBR might be collapsed
in a single node, in which case the flow above happens internally, in a single node, in which case the flow above happens internally,
and possibly through internal API calls as opposed to messaging. and possibly through internal API calls as opposed to messaging.
11. Security Considerations 11. Security Considerations
First of all, it is worth noting that with [RFC6550], every node in It is worth noting that with [RFC6550], every node in the LLN is RPL-
the LLN is RPL-aware and can inject any RPL-based attack in the aware and can inject any RPL-based attack in the network. This
network. This specification isolates edge nodes that can only specification isolates edge nodes that can only interact with the RPL
interact with the RPL Routers using 6LoWPAN ND, meaning that they Routers using 6LoWPAN ND, meaning that they cannot perform RPL
cannot perform RPL insider attacks. insider attacks.
6LoWPAN ND can optionally provide SAVI features with [AP-ND], which
reduces even more the attack perimeter that is available to the edge
nodes.
The LLN nodes depend on the 6LBR and the RPL participants for their The LLN nodes depend on the 6LBR and the RPL participants for their
operation. A trust model must be put in place to ensure that the operation. A trust model must be put in place to ensure that the
right devices are acting in these roles, so as to avoid threats such right devices are acting in these roles, so as to avoid threats such
as black-holing, (see [RFC7416] section 7), Denial-Of-Service attacks as black-holing, (see [RFC7416] section 7), Denial-Of-Service attacks
whereby a rogue 6LR creates a high churn in the RPL network by whereby a rogue 6LR creates a high churn in the RPL network by
advertising and removing many forged addresses, or bombing attack advertising and removing many forged addresses, or bombing attack
whereby an impersonated 6LBR would destroy state in the network by whereby an impersonated 6LBR would destroy state in the network by
using the "Removed" Status code. using the "Removed" Status code.
This trust model could be at a minimum based on a Layer-2 Secure This trust model could be at a minimum based on a Layer-2 Secure
joining and the Link-Layer security. This is a generic 6LoWPAN joining and the Link-Layer security. This is a generic 6LoWPAN
requirement, see Req5.1 in Appendix of [RFC8505]. It is needed in requirement, see Req5.1 in Appendix of [RFC8505].
particular to prevent Denial-Of-Service attacks whereby a rogue 6LN
creates a high churn in the RPL network by constantly registering and In a general manner, the Security Considerations in [RFC7416]
deregistering addresses with the "R" flag set in the EARO. [RFC6775], and [RFC8505] apply to this specification as well.
The Link-Layer security is needed in particular to prevent Denial-Of-
Service attacks whereby a rogue 6LN creates a high churn in the RPL
network by constantly registering and deregistering addresses with
the R Flag set in the EARO.
[AP-ND] updated 6LoWPAN ND with the called Address-Protected Neighbor
Discovery (AP-ND). AP-ND protects the owner of an address against
address theft and impersonation attacks in a Low-Power and Lossy
Network (LLN). Nodes supporting th extension compute a cryptographic
identifier (Crypto-ID), and use it with one or more of their
Registered Addresses. The Crypto-ID identifies the owner of the
Registered Address and can be used to provide proof of ownership of
the Registered Addresses. Once an address is registered with the
Crypto-ID and a proof of ownership is provided, only the owner of
that address can modify the registration information, thereby
enforcing Source Address Validation. [AP-ND] reduces even more the
attack perimeter that is available to the edge nodes and its use is
suggested in this specification.
Additionally, the trust model could include a role validation to Additionally, the trust model could include a role validation to
ensure that the node that claims to be a 6LBR or a RPL Root is ensure that the node that claims to be a 6LBR or a RPL Root is
entitled to do so. entitled to do so.
At the time of this writing RPL does not have a zerotrust model The Opaque field in the EARO enables the RUL to suggest a
whereby it is possible to validate the origin of an address that is RPLInstanceID where its traffic is placed. This opens to attacks
injected in a DAO. This specification makes a first step in that where a RPL instance would be reserved for critical traffic, e.g.,
direction by allowing the Root to challenge the RUL via the 6LR that with a specific bandwidth reservation, that the additional traffic
serves it. generated by a rogue may disrupt. This may be alleviated by
traditional access control mechanisms where the 6LR shapes the
incoming traffic from the 6LN.
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
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
the 6LR that serves it.
[EFFICIENT-NPDAO] introduces the ability for a rogue common ancestor
node to invalidate a route on behalf of the target node. In that
case, the RPL Status in the DCO has the 'A' flag not set, and a
NA(EARO) is returned to the 6LN with the R flag not set. This
encourages the 6LN to try another 6LR. If a 6LR exists that does not
use the rogue common ancestor, then the 6LN will eventually succeed
gaining 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] creates a Registry for the 8-bit Address
Registration Option Flags field. IANA is requested to rename the Registration Option Flags field. IANA is requested to rename the
first column of the table from "ARO Status" to "Bit number". first column 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] creates the Address Registration Option
Status Values Registry with a range 0-255. Status Values Registry with a range 0-255.
This specification reduces that range to 0-63. This specification reduces that range to 0-63, see Section 6.3.
IANA is requested to reduce the upper bound of the unassigned values IANA is requested modify the Address Registration Option Status
in the Address Registration Option Status Values Registry from -255 Values Registry so that the upper bound of the unassigned values is
to -63. 63. This document should be added as a reference. The registration
procedure does not change.
12.3. New DODAG Configuration Option Flag 12.3. New DODAG Configuration Option Flag
This specification updates the Registry that was created for This specification updates the Registry that was created for
[RFC6550] as the registry for "DODAG Configuration Option Flags" and [RFC6550] as the registry for "DODAG Configuration Option Flags" and
updated as the registry for "DODAG Configuration Option Flags for MOP updated as the registry for "DODAG Configuration Option Flags for MOP
0..6" by [USEofRPLinfo], by allocating one new Flag as follows: 0..6" by [USEofRPLinfo], by allocating one new Flag as follows:
+------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
| 1 | Root Proxies EDAR/EDAC (P) | THIS RFC | | 1 (suggested) | Root Proxies EDAR/EDAC (P) | THIS RFC |
+------------+----------------------------+-----------+ +---------------+----------------------------+-----------+
Table 2: New DODAG Configuration Option Flag Table 2: New DODAG Configuration Option Flag
12.4. New RPL Target Option Flag 12.4. RPL Target Option Registry
Section 20.15 of [RFC6550] creates a Registry for the 8-bit "RPL Section 20.15 of [RFC6550] creates a Registry for the 8-bit "RPL
Target Option Flags" field. IANA is requested to reduce the size of Target Option Flags" field. IANA is requested to reduce the size of
the field in the Registry to 4 bits. This specification also defines the field in the Registry to 4 bits. Section 6.1 also defines a new
a new entry in the Registry as follows: entry in the Registry as follows:
+------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
| 1 | Advertiser Address in Full (F) | THIS RFC | | 1 (suggested) | Advertiser address in Full (F) | THIS RFC |
+------------+--------------------------------+-----------+ +---------------+--------------------------------+-----------+
Table 3: New RPL Target Option Flag Table 3: RPL Target Option Registry
12.5. New Subregistry for the RPL Non-Rejection Status values 12.5. New Subregistry for the RPL Non-Rejection Status values
This specification creates a new Subregistry for the RPL Non- This specification creates a new Subregistry for the RPL Non-
Rejection Status values for use in RPL DAO-ACK and DCO messages with Rejection Status values for use in the RPL DAO-ACK and DCO messages
the 'A' flag reset, under the ICMPv6 parameters registry. with the 'A' flag reset, under the RPL registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "IETF Review" [RFC8126].
* Initial allocation is as indicated in Table 4: * Initial allocation is as indicated in Table 4:
+-------+------------------------+-----------+ +-------+--------------------------+-------------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+------------------------+-----------+ +-------+--------------------------+-------------------+
| 0 | Unqualified acceptance | RFC 6550 | | 0 | Unqualified acceptance | THIS RFC |
+-------+------------------------+-----------+ +-------+--------------------------+-------------------+
| 1 | No routing-entry for the | [EFFICIENT-NPDAO] |
| | indicated Target found | |
+-------+--------------------------+-------------------+
Table 4: Acceptance values of the RPL Status Table 4: Acceptance values of the RPL Status
12.6. New Subregistry for the RPL Rejection Status values 12.6. New Subregistry for the RPL Rejection Status values
This specification creates a new Subregistry for the RPL Rejection This specification creates a new Subregistry for the RPL Rejection
Status values for use in RPL DAO-ACK and RCO messages with the 'A' Status values for use in the RPL DAO-ACK and DCO messages with the
flag reset, under the ICMPv6 parameters registry. 'A' flag reset, under the RPL registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "IETF Review" [RFC8126].
* Initial allocation is as indicated in Table 5: * Initial allocation is as indicated in Table 5:
+-------+-----------------------+---------------+ +-------+-----------------------+-----------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+-----------------------+---------------+ +-------+-----------------------+-----------+
| 0 | Unqualified rejection | This document | | 0 | Unqualified rejection | THIS RFC |
+-------+-----------------------+---------------+ +-------+-----------------------+-----------+
Table 5: Rejection values of the RPL Status Table 5: Rejection values of the RPL Status
13. Acknowledgments 13. Acknowledgments
The authors wish to thank Ines Robles, Georgios Papadopoulos and The authors wish to thank Ines Robles, Georgios Papadopoulos and
especially Rahul Jadhav and Alvaro Retana for their reviews and especially Rahul Jadhav and Alvaro Retana for their reviews and
contributions to this document. contributions to this document.
14. Normative References 14. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710,
DOI 10.17487/RFC2710, October 1999,
<https://www.rfc-editor.org/info/rfc2710>.
[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>.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007,
<https://www.rfc-editor.org/info/rfc4919>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
[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>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012,
<https://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012,
<https://www.rfc-editor.org/info/rfc6554>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012, RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <https://www.rfc-editor.org/info/rfc7102>. 2014, <https://www.rfc-editor.org/info/rfc7102>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
IPv6 over Low-Power Wireless Personal Area Networks IPv6 over Low-Power Wireless Personal Area Networks
(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
2014, <https://www.rfc-editor.org/info/rfc7400>. 2014, <https://www.rfc-editor.org/info/rfc7400>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
January 2019, <https://www.rfc-editor.org/info/rfc8504>.
[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
Perkins, "Registration Extensions for IPv6 over Low-Power Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, [AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
"Address Protected Neighbor Discovery for Low-power and "Address Protected Neighbor Discovery for Low-power and
Lossy Networks", Work in Progress, Internet-Draft, draft- Lossy Networks", Work in Progress, Internet-Draft, draft-
ietf-6lo-ap-nd-23, 30 April 2020, ietf-6lo-ap-nd-23, 30 April 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-23>. <https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-23>.
[USEofRPLinfo] [USEofRPLinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPI Robles, I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes and IPv6-in- Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", Work in IPv6 encapsulation in the RPL Data Plane", Work in
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-40, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-41,
25 June 2020, <https://tools.ietf.org/html/draft-ietf- 21 September 2020, <https://tools.ietf.org/html/draft-
roll-useofrplinfo-40>. ietf-roll-useofrplinfo-41>.
[EFFICIENT-NPDAO] [EFFICIENT-NPDAO]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", Work in Progress, Internet-Draft, Route Invalidation", Work in Progress, Internet-Draft,
draft-ietf-roll-efficient-npdao-18, 15 April 2020, draft-ietf-roll-efficient-npdao-18, 15 April 2020,
<https://tools.ietf.org/html/draft-ietf-roll-efficient- <https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-18>. npdao-18>.
15. Informative References 15. Informative References
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007,
<https://www.rfc-editor.org/info/rfc4919>.
[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>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012,
<https://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012,
<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>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed.,
C., and M. Carney, "Dynamic Host Configuration Protocol "Source Address Validation Improvement (SAVI) Framework",
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July RFC 7039, DOI 10.17487/RFC7039, October 2013,
2003, <https://www.rfc-editor.org/info/rfc3315>. <https://www.rfc-editor.org/info/rfc7039>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<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 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
[RFC6687] Tripathi, J., Ed., de Oliveira, J., Ed., and JP. Vasseur, [RFC6687] Tripathi, J., Ed., de Oliveira, J., Ed., and JP. Vasseur,
Ed., "Performance Evaluation of the Routing Protocol for Ed., "Performance Evaluation of the Routing Protocol for
Low-Power and Lossy Networks (RPL)", RFC 6687, Low-Power and Lossy Networks (RPL)", RFC 6687,
DOI 10.17487/RFC6687, October 2012, DOI 10.17487/RFC6687, October 2012,
skipping to change at page 32, line 5 skipping to change at page 36, line 38
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>.
[RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
January 2019, <https://www.rfc-editor.org/info/rfc8504>.
[6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 [6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", Work in Progress, Internet-Draft, draft- Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-20, 23 March 2020, ietf-6lo-backbone-router-20, 23 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-backbone- <https://tools.ietf.org/html/draft-ietf-6lo-backbone-
router-20>. router-20>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 11 illustrates the case in Storing Mode where the packet is Figure 12 illustrates the case in Storing Mode where the packet is
received from the Internet, then the Root encapsulates the packet to received from the Internet, then the Root encapsulates the packet to
insert the RPI and deliver to the 6LR that is the parent and last hop insert the RPI and deliver to the 6LR that is the parent and last hop
to the final destination, which is not known to support [RFC8138]. to the final destination, which is not known to support [RFC8138].
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4 bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
<- No RPL artifact ... <- No RPL artifact ...
Figure 11: Encapsulation to Parent 6LR in Storing Mode Figure 12: Encapsulation to Parent 6LR in Storing Mode
The difference with the example presented in Figure 19 of [RFC8138] The difference with the example presented in Figure 19 of [RFC8138]
is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
compressed address of the 6LR as the destination address of the outer compressed address of the 6LR as the destination address of the outer
IPv6 header. In the original example the destination IP of the outer IPv6 header. In the [RFC8138] example the destination IP of the
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 11, the source of the IP-in-IP encapsulation is the Root, In Figure 12, the source of the IP-in-IP encapsulation is the Root,
so it is elided in the IP-in-IP 6LoRH. The destination is the parent so it is elided in the IP-in-IP 6LoRH. The destination is the parent
6LR of the destination of the inner packet so it cannot be elided. 6LR of the destination of the inner packet so it cannot be elided.
If the DODAG is operated in Storing Mode, it is the single entry in If the DODAG is operated in Storing Mode, it is the single entry in
the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH the SRH-6LoRH and the SRH-6LoRH Size is encoded as 0. The SRH-6LoRH
is the first 6LoRH in the chain. In this particular example, the 6LR is the first 6LoRH in the chain. In this particular example, the 6LR
address can be compressed to 2 bytes so a Type of 1 is used. It address can be compressed to 2 bytes so a Type of 1 is used. It
results that the total length of the SRH-6LoRH is 4 bytes. results that the total length of the SRH-6LoRH is 4 bytes.
In Non-Storing Mode, the encapsulation from the Root would be similar In Non-Storing Mode, the encapsulation from the Root would be similar
to that represented in Figure 11 with possibly more hops in the SRH- to that represented in Figure 12 with possibly more hops in the SRH-
6LoRH and possibly multiple SRH-6LoRHs if the various addresses in 6LoRH and possibly multiple SRH-6LoRHs if the various addresses in
the routing header are not compressed to the same format. Note that the routing header are not compressed to the same format. Note that
on the last hop to the parent 6LR, the RH3 is consumed and removed on the last hop to the parent 6LR, the RH3 is consumed and removed
from the compressed form, so the use of Non-Storing Mode vs. Storing from the compressed form, so the use of Non-Storing Mode vs. Storing
Mode is indistinguishable from the packet format. Mode is indistinguishable from the packet format.
The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH. The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH.
When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that
precede it are also removed. The Paging Dispatch [RFC8025] may also precede it are also removed. The Paging Dispatch [RFC8025] may also
be removed if there was no previous Page change to a Page other than be removed if there was no previous Page change to a Page other than
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