draft-ietf-roll-dao-projection-11.txt   draft-ietf-roll-dao-projection-12.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550 (if approved) R.A. Jadhav Updates: 6550 (if approved) R.A. Jadhav
Intended status: Standards Track Huawei Tech Intended status: Standards Track Huawei Tech
Expires: March 15, 2021 M. Gillmore Expires: 25 March 2021 M. Gillmore
Itron Itron
September 11, 2020 21 September 2020
Root initiated routing state in RPL Root initiated routing state in RPL
draft-ietf-roll-dao-projection-11 draft-ietf-roll-dao-projection-12
Abstract Abstract
This document enables a RPL Root to install and maintain Projected This document enables a RPL Root to install and maintain Projected
Routes within its DODAG, along a selected set of nodes that may or Routes within its DODAG, along a selected set of nodes that may or
may not include self, for a chosen duration. This potentially may not include self, for a chosen duration. This potentially
enables routes that are more optimized or resilient than those enables routes that are more optimized or resilient than those
obtained with the classical distributed operation of RPL, either in obtained with the classical distributed operation of RPL, either in
terms of the size of a source-route header or in terms of path terms of the size of a source-route header or in terms of path
length, which impacts both the latency and the packet delivery ratio. length, which impacts both the latency and the packet delivery ratio.
Projected Routes may be installed in either Storing and Non-Storing
Modes Instances of the classical RPL operation, resulting in
potentially hybrid situations where the mode of some Projected Routes
is different from that of the other routes in the RPL Instance.
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 March 15, 2021. This Internet-Draft will expire on 25 March 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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provided without warranty as described in the Simplified BSD License. provided without warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Other Terms . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Other Terms . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6
3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 6 3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 6
4. Identifying a Path . . . . . . . . . . . . . . . . . . . . . 7 4. Identifying a Path . . . . . . . . . . . . . . . . . . . . . 7
5. New RPL Control Messages and Options . . . . . . . . . . . . 8 5. New RPL Control Messages and Options . . . . . . . . . . . . 8
5.1. New P-DAO Request Control Message . . . . . . . . . . . . 8 5.1. New P-DAO Request Control Message . . . . . . . . . . . . 8
5.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 9 5.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 9
5.3. Route Projection Options . . . . . . . . . . . . . . . . 10 5.3. Route Projection Options . . . . . . . . . . . . . . . . 10
5.4. Sibling Information Option . . . . . . . . . . . . . . . 12 5.4. Sibling Information Option . . . . . . . . . . . . . . . 13
6. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Non-Storing Mode Projected Route . . . . . . . . . . . . 15 6.1. Requesting a Track . . . . . . . . . . . . . . . . . . . 16
6.2. Storing-Mode Projected Route . . . . . . . . . . . . . . 17 6.2. Routing over a Track . . . . . . . . . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19 6.3. Non-Storing Mode Projected Route . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 6.4. Storing-Mode Projected Route . . . . . . . . . . . . . . 18
8.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 19 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21
8.2. New RPL Control Message Options . . . . . . . . . . . . . 19 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8.3. New SubRegistry for the Projected DAO Request (PDR) 8.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 21
Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.2. New RPL Control Message Options . . . . . . . . . . . . . 21
8.4. New SubRegistry for the PDR-ACK Flags . . . . . . . . . . 20 8.3. SubRegistry for the Projected DAO Request Flags . . . . . 22
8.5. New Subregistry for the PDR-ACK Acceptance Status 8.4. SubRegistry for the PDR-ACK Flags . . . . . . . . . . . . 22
values . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.5. Subregistry for the PDR-ACK Acceptance Status Values . . 22
8.6. New Subregistry for the PDR-ACK Rejection Status 8.6. Subregistry for the PDR-ACK Rejection Status Values . . . 23
values . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.7. SubRegistry for the Route Projection Options Flags . . . 23
8.7. New SubRegistry for the Route Projection Options (RPO) 8.8. SubRegistry for the Sibling Information Option Flags . . 24
Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.9. Error in Projected Route ICMPv6 Code . . . . . . . . . . 24
8.8. New SubRegistry for the Sibling Information Option (SIO) 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 22 10. Normative References . . . . . . . . . . . . . . . . . . . . 24
8.9. Error in Projected Route ICMPv6 Code . . . . . . . . . . 22 11. Informative References . . . . . . . . . . . . . . . . . . . 25
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 26
10. Normative References . . . . . . . . . . . . . . . . . . . . 23 A.1. Loose Source Routing . . . . . . . . . . . . . . . . . . 27
11. Informative References . . . . . . . . . . . . . . . . . . . 23 A.2. Transversal Routes . . . . . . . . . . . . . . . . . . . 28
Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 24 Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 30
A.1. Loose Source Routing in Non-storing Mode . . . . . . . . 25 B.1. Using Storing Mode P-DAO in Non-Storing Mode MOP . . . . 30
A.2. Transversal Routes in storing and non-storing modes . . . 26 B.2. Projecting a storing-mode transversal route . . . . . . . 31
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
B.1. Using storing mode P-DAO in non-storing mode MOP . . . . 28
B.2. Projecting a storing-mode transversal route . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
RPL, the "Routing Protocol for Low Power and Lossy Networks" [RPL] RPL, the "Routing Protocol for Low Power and Lossy Networks" [RPL]
(LLNs), is a generic Distance Vector protocol that is well suited for (LLNs), is a generic Distance Vector protocol that is well suited for
application in a variety of low energy Internet of Things (IoT) application in a variety of low energy Internet of Things (IoT)
networks. RPL forms Destination Oriented Directed Acyclic Graphs networks. RPL forms Destination Oriented Directed Acyclic Graphs
(DODAGs) in which the Root often acts as the Border Router to connect (DODAGs) in which the Root often acts as the Border Router to connect
the RPL domain to the Internet. The Root is responsible to select the RPL domain to the Internet. The Root is responsible to select
the RPL Instance that is used to forward a packet coming from the the RPL Instance that is used to forward a packet coming from the
skipping to change at page 3, line 40 skipping to change at page 3, line 35
Based on heuristics of usage, path length, and knowledge of device Based on heuristics of usage, path length, and knowledge of device
capacity and available resources such as battery levels and capacity and available resources such as battery levels and
reservable buffers, a PCE with a global visibility on the system can reservable buffers, a PCE with a global visibility on the system can
compute P2P routes that are more optimized for the current needs as compute P2P routes that are more optimized for the current needs as
expressed by the objective function. expressed by the objective function.
This draft proposes protocol extensions to RPL that enable the Root This draft proposes protocol extensions to RPL that enable the Root
to install a limited amount of centrally-computed routes in a RPL to install a limited amount of centrally-computed routes in a RPL
graph, on behalf of a PCE that may be collocated or separated from graph, on behalf of a PCE that may be collocated or separated from
the Root. Those extensions enable loose source routing down in RPL the Root. Those extensions enable loose source routing down and
Non-Storing Mode and transversal routes inside the DODAG regardless transversal routes inside the main DODAG running a base RPL Instance.
of the RPL Mode of Operation (MOP).
This specification expects that the base RPL Instance is operated in
RPL Non-Storing Mode of Operation (MOP) to sustain the exchanges with
the Root. In that Mode, the Root has enough information to build a
basic DODAG topology based on parents and children, but lacks the
knowledge of siblings. This document adds the capability for nodes
to advertise sibling information in order to improve the topological
awareness of the Root.
As opposed to the classical RPL operations where routes are injected As opposed to the classical RPL operations where routes are injected
by the Target nodes, the protocol extensions enable the Root of a by the Target nodes, the protocol extensions enable the Root of a
DODAG to project the routes that are needed onto the nodes where they DODAG to project the routes that are needed onto the nodes where they
should be installed. This specification uses the term Projected should be installed. This specification uses the term Projected
Route to refer to those routes. A Projected Route may be a stand- Route to refer to those routes.
alone end-to-end path to a Target or a segment in a more complex
forwarding graph called a Track. A Projected Route may be installed in either Storing and Non-Storing
Mode, potentially resulting in hybrid situations where the Mode of
the Projected Route is different from that of the main RPL Instance.
A Projected Route may be a stand-alone end-to-end path to a Target or
a Segment in a more complex forwarding graph called a Track.
The concept of a Track was introduced in the 6TiSCH architecture, as The concept of a Track was introduced in the 6TiSCH architecture, as
a complex path with redundant forwarding solutions along the way. A a complex path to a Target destination with redundant forwarding
node that is present on more than one segment in a Track may be able solutions along the way. A node at the ingress of more than one
to use either of the Track segments to forward a packet towards the Segment in a Track may use any combination of those Segments to
Target. forward a packet towards the Target.
The "Reliable and Available Wireless (RAW) Architecture/Framework" The "Reliable and Available Wireless (RAW) Architecture/Framework"
[RAW-ARCHI] extends the the forward plane to leverage that redundancy [RAW-ARCHI] enables a dynamic path selection within the Track to
with the Packet ARQ, Replication, Elimination, and Overhearing increase the transmission diversity and combat diverse causes of
(PAREO) functions. packet loss.
The RAW Architecture also discusses the dynamic selection of the best To that effect, RAW defines the Path Selection Engine (PSE) as a
path for a packet within a Track at forwarding time. To that effect, complement of the PCE operating in the dataplane. The PSE controls
it defines the Path Selection Engine (PSE), which is the counter-part the use of the Packet ARQ, Replication, Elimination, and Overhearing
of the PCE to perform rapid local adjustments of the forwarding (PAREO) functions over the Track segments.
tables within the path diversity that the PCE has selected for the
Track.
RAW differentiates the time scale at which the PCE computes the Track While the time scale at which the PCE (re)computes the Track can be
(slow, globally optimized, based on statistical metrics) and the time long, for an operation based on long-term statistical metrics to
scale at which the PSE makes the forwarding decision for a packet or perform global optimizations at the scale of the whole network, the
a small collection of packets (fast, but with a scope limited to the PSE makes forwarding decision at the time scale of one or a small
Track). This provides a dynamic balance between the reliability and collection of packets, using a knowledge that is changing rapidly but
availability requirements of the flows and the need to conserve limited in scope of the Track itself. This way, the PSE can provide
energy and spectrum. a dynamic balance between the reliability and availability
requirements of the flows and the need to conserve energy and
spectrum.
Projected Routes must be used with the parsimony to limit the amount Projected Routes must be used with the parsimony to limit the amount
of state that is installed in each device to fit within the device of state that is installed in each device to fit within the device
resources, and to maintain the amount of rerouted traffic within the resources, and to maintain the amount of rerouted traffic within the
capabilities of the transmission links. The methods used to learn capabilities of the transmission links. The methods used to learn
the node capabilities and the resources that are available in the the node capabilities and the resources that are available in the
devices and in the network are out of scope for this document. devices and in the network are out of scope for this document.
This specification expects that a base RPL Instance is operated in
RPL Non-Storing Mode to sustain the exchanges with the Root. In that
Mode, the Root has enough information to build a basic DODAG topology
based on parents and children, but lacks the knowledge of siblings.
This document adds the capability for nodes to advertise sibling
information in order to improve the topological awareness of the
Root.
This specification uses the RPL Root as a proxy to the PCE. The PCE This specification uses the RPL Root as a proxy to the PCE. The PCE
may be collocated with the Root, or may reside in an external may be collocated with the Root, or may reside in an external
Controller. In that case, the PCE exchanges control messages with Controller. In that case, the PCE exchanges control messages with
the Root over a Southbound API, that is out of scope for this the Root over a Southbound API, that is out of scope for this
specification. The algorithm to compute the paths and the protocol specification. The algorithm to compute the paths and the protocol
used by an external PCE to obtain the topology of the network from used by an external PCE to obtain the topology of the network from
the Root are also out of scope. the Root are also out of scope.
2. Terminology 2. Terminology
2.1. Requirements Language 2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. References 2.2. Glossary
In this document, readers will encounter terms and concepts that are
discussed in the "Routing Protocol for Low Power and Lossy Networks"
[RPL] and "Terminology in Low power And Lossy Networks" [RFC7102].
2.3. Glossary
This document often uses the following acronyms: This document often uses the following acronyms:
6BBR: 6LoWPAN Backbone Router
6LBR: 6LoWPAN Border Router
6LN: 6LoWPAN Node
6LR: 6LoWPAN Router
CMO: Control Message Option CMO: Control Message Option
DAO: Destination Advertisement Object DAO: Destination Advertisement Object
DODAG: Destination-Oriented Directed Acyclic Graph DAG: Directed Acyclic Graph
DODAG: Destination-Oriented Directed Acyclic Graph; A DAG with only
one vertice (i.e., node) that has no outgoing edge (i.e., link)
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
MOP: RPL Mode of Operation MOP: RPL Mode of Operation
NA: Neighbor Advertisement P-DAO: Projected DAO
NCE: Neighbor Cache Entry PDR: P-DAO Request
ND: Neighbor Discovery RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf)
NDP: Neighbor Discovery Protocol RAL: RPL-Aware Leaf
NS: Neighbor Solicitation RPI: RPL Packet Information
P-DAO: A Projected DAO is a DAO message sent by the RPL Root to
install a Projected Route.
PDR P-DAO Request
RA: Router Advertisement
RAN: RPL-Aware Node
RS: Router Solicitation
RPL: IPv6 Routing Protocol for LLNs [RPL] RPL: IPv6 Routing Protocol for LLNs [RPL]
RPO: A Route Projection Option; it can be a VIO or an SRVIO. RPO: A Route Projection Option; it can be a VIO or an SRVIO.
RTO: RPL Target Option RTO: RPL Target Option
RUL: RPL-Unaware Leaf
SIO: RPL Sibling Information Option SIO: RPL Sibling Information Option
SRVIO: A Source-Routed Via Information Option, used in Non-Storing SRVIO: A Source-Routed Via Information Option, used in Non-Storing
Mode P-DAO messages. Mode P-DAO messages.
SubDAG: A DODAG rooted at a node which is a child of that node and a
subset of a larger DAG
TIO: RPL Transit Information Option TIO: RPL Transit Information Option
VIO: A Via Information Option, used in Storing Mode P-DAO messages. VIO: A Via Information Option, used in Storing Mode P-DAO messages.
2.4. Other Terms 2.3. Other Terms
Projected Route: A Projected Route is a serial path or path segment Projected Route: A Projected Route is a serial path that is
that is computed, installed and maintained remotely by a RPL Root. computed, installed and maintained remotely by a RPL Root.
Track: The term Track is used in this document to refer to a complex Projected DAO: A DAO message used to install a Projected Route.
path, e.g., a DODAG, that incorporates redundant Projected Routes Track: A complex path with redundant Segments to a destination.
towards a destination using diversity to increase the reliability. TrackID: A RPL Local InstanceID with the 'D' bit set. The TrackId
is associated with a Target address that is the Track destination.
2.4. References
In this document, readers will encounter terms and concepts that are
discussed in the "Routing Protocol for Low Power and Lossy Networks"
[RPL] and "Terminology in Low power And Lossy Networks" [RFC7102].
3. Updating RFC 6550 3. Updating RFC 6550
This specification introduces two new RPL Control Messages to enable This specification introduces two new RPL Control Messages to enable
a RPL Aware Node (RAN) to request the establisment of a Track from a RPL Aware Node (RAN) to request the establisment of a Track from
self to a Target. The RAN makes its request by sending a new P-DAO self to a Target. The RAN makes its request by sending a new P-DAO
Request (PDR) Message to the Root. The Root confirms with a new PDR- Request (PDR) Message to the Root. The Root confirms with a new PDR-
ACK message back to the requester RAN, see Section 5.1 for more. ACK message back to the requester RAN, see Section 5.1 for more.
Section 6.7 of [RPL] specifies the RPL Control Message Options (CMO) Section 6.7 of [RPL] specifies the RPL Control Message Options (CMO)
skipping to change at page 7, line 21 skipping to change at page 7, line 21
routing information within one routing topology. routing information within one routing topology.
This draft conforms the Instance model as follows: This draft conforms the Instance model as follows:
* If the PCE needs to influence a particular Instance to add better * If the PCE needs to influence a particular Instance to add better
routes in conformance with the routing objectives in that routes in conformance with the routing objectives in that
Instance, it may do so as long as it does not create a loop. A Instance, it may do so as long as it does not create a loop. A
Projected Route is always preferred over a route that is learned Projected Route is always preferred over a route that is learned
via RPL. via RPL.
* A PCE that installs a more specific (say, Traffic Engineered) and * The PCE may use P-DAOs to install a specific (say, Traffic
possibly complex path (i.e., a Track) towards a particular Target Engineered) and possibly complex path, that we refer to as a
MUST use a Local RPL Instance (see section 5 of [RPL]) associated Track, towards a particular Target. In that case it MUST use a
to that Target to identify the path. Local RPL Instance (see section 5 of [RPL]) associated to that
Target to identify the Track.
We refer to that Local RPLInstanceID as TrackID. A TrackID MUST We refer to the local RPLInstanceID as TrackID. The TrackID MUST
be unique for a particular Target address. A Track is uniquely be unique for a particular Target IPv6 address. The Track is
identified within the RPL domain by the tuple (Target address, uniquely identified within the RPL domain by the tuple (Target
TrackID). address, TrackID) where the TrackID is always represented with the
'D' flag set.
When packet is placed on a Track, a RPL Packet Information (RPI) The Track where a packet is placed is signaled by a RPL Packet
is added with the TrackID as RPLInstanceID. The RPLInstanceID has Information (RPI) (see [USEofRPLinfo]) in the outer chain of IPv6
the 'D' flag set, indicating that the destination address in the Headers. The RPI contains the TrackID as RPLInstanceID and the
IPv6 header is the Target that is used to identify the Track. 'D' flag is set to indicate that the destination address in the
IPv6 header is the Target that is used to identify the Track, more
in Section 6.2.
* The PCE may also install a projected Route as a complement to the
main DODAG, e.g., using the Storing-Mode Mode along a Source-
Routed path in order to enable loose source routing and reduce the
Routing Header. In that case, the global RPLInstanceID of the
main DODAG is signaled in place of the TrackId on the P-DAO, and
the RPI in the packet indicates the global RPLInstanceID, more in
Appendix A.1.
* A packet that is routed over the RPL Instance associated to a * A packet that is routed over the RPL Instance associated to a
Track MUST NOT be placed over a different RPL Instance again. Track MUST NOT be placed over a different RPL Instance again.
Conversely, a packet that is placed on a Global Instance MAY be Conversely, a packet that is placed on a Global Instance MAY be
injected in a Local Instance based on a network policy and the injected in a Local Instance based on a network policy and the
Local Instance configuration. Local Instance configuration.
A Projected Route is a serial path that may represent the end-to-end A Projected Route is a serial path that may represent the end-to-end
route or only a segment in a complex Track, in which case multiple route or only a Segment in a complex Track, in which case multiple
Projected Routes are installed with the same tuple (Target address, Projected Routes are installed with the same tuple (Target address,
TrackID) and a different segment ID each. TrackID) and a different Segment ID each.
All properties of a Track operations are inherited form the main All properties of a Track operations are inherited form the main
instance that is used to install the Track. For instance, the use of instance that is used to install the Track. For instance, the use of
compression per [RFC8138] is determined by whether it is used in the compression per [RFC8138] is determined by whether it is used in the
main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the
RPL configuration option. RPL configuration option.
5. New RPL Control Messages and Options 5. New RPL Control Messages and Options
5.1. New P-DAO Request Control Message 5.1. New P-DAO Request Control Message
The P-DAO Request (PDR) message is sent to the Root to request a new The P-DAO Request (PDR) message is sent to the Root to request a new
that the PCE establishes a new a projected route as a full path of a that the PCE establishes a new a projected route from self ot the
collection of segments in a Track. Exactly one Target Options MUST Target indicated in the Target Option as a full path of a collection
be present. of Segments in a Track. Exactly one Target Option MUST be present,
more in Section 6.1.
The RPL Control Code for the PDR is 0x09, to be confirmed by IANA.
The format of PDR Base Object is as follows: The format of PDR Base Object is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TrackID |K|R| Flags | PDRLifetime | PDRSequence | | TrackID |K|R| Flags | ReqLifetime | PDRSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: New P-DAO Request Format Figure 1: New P-DAO Request Format
TrackID: 8-bit field indicating the RPLInstanceID associated with TrackID: 8-bit field indicating the RPLInstanceID associated with
the Track. It is set to zero upon the first request for a new the Track. It is set to zero upon the first request for a new
Track and then to the TrackID once the Track was created, to Track and then to the TrackID once the Track was created, to
either renew it of destroy it. either renew it of destroy it.
K: The 'K' flag is set to indicate that the recipient is expected to K: The 'K' flag is set to indicate that the recipient is expected to
send a PDR-ACK back. send a PDR-ACK back.
R: The 'R' flag is set to indicate that the Requested path should be R: The 'R' flag is set to indicate that the Requested path should be
redundant. redundant.
PDRLifetime: 8-bit unsigned integer. Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver
ReqLifetime: 8-bit unsigned integer.
The requested lifetime for the Track expressed in Lifetime Units The requested lifetime for the Track expressed in Lifetime Units
(obtained from the DODAG Configuration option). (obtained from the DODAG Configuration option).
A PDR with a fresher PDRSequence refreshes the lifetime, and a A PDR with a fresher PDRSequence refreshes the lifetime, and a
PDRLifetime of 0 indicates that the track should be destroyed. PDRLifetime of 0 indicates that the track should be destroyed.
PDRSequence: 8-bit wrapping sequence number, obeying the operation PDRSequence: 8-bit wrapping sequence number, obeying the operation
in section 7.2 of [RPL]. in section 7.2 of [RPL].
The PDRSequence is used to correlate a PDR-ACK message with the The PDRSequence is used to correlate a PDR-ACK message with the
PDR message that triggeted it. It is incremented at each PDR PDR message that triggeted it. It is incremented at each PDR
message and echoed in the PDR-ACK by the Root. message and echoed in the PDR-ACK by the Root.
5.2. New PDR-ACK Control Message 5.2. New PDR-ACK Control Message
The new PDR-ACK is sent as a response to a PDR message with the 'K' The new PDR-ACK is sent as a response to a PDR message with the 'K'
flag set. Its format is as follows: flag set. The RPL Control Code for the PDR-ACK is 0x0A, to be
confirmed by IANA. Its format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TrackID | Flags | Track Lifetime| PDRSequence | | TrackID | Flags | Track Lifetime| PDRSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PDR-ACK Status| Reserved | | PDR-ACK Status| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
Figure 2: New PDR-ACK Control Message Format Figure 2: New PDR-ACK Control Message Format
TrackID: The RPLInstanceID of the Track that was created. Set to 0 TrackID: The RPLInstanceID of the Track that was created. The value
when no Track is created. of 0x00 is used to when no Track was created.
Track Lifetime: Indicates that remaining Lifetime for the Track, 0 Flags: Reserved. The Flags field MUST initialized to zero by the
if the Track was destroyed or not created. sender and MUST be ignored by the receiver
Track Lifetime: Indicates that remaining Lifetime for the Track,
expressed in Lifetime Units; a value of zero (0x00) indicates that
the Track was destroyed or not created.
PDRSequence: 8-bit wrapping sequence number. It is incremented at PDRSequence: 8-bit wrapping sequence number. It is incremented at
each PDR message and echoed in the PDR-ACK. each PDR message and echoed in the PDR-ACK.
PDR-ACK Status: 8-bit field indicating the completion. PDR-ACK Status: 8-bit field indicating the completion.
The PDR-ACK Status is further substructured as indicated in The PDR-ACK Status is substructured as indicated in Figure 3:
Figure 3.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|R| Value | |E|R| Value |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 3: PDR-ACK status Format Figure 3: PDR-ACK status Format
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
of 0 indicates Success/Unqualified acceptance and other values value of 0 indicates Success/Unqualified acceptance and other
indicate "not an outright rejection". values indicate "not an outright rejection".
R: 1-bit flag. Reserved, MUST be set to 0 by the sender and ignored R: 1-bit flag. Reserved, MUST be set to 0 by the sender and
by the receiver. ignored by the receiver.
Status Value: 6-bit unsigned integer. Values depending on the Status Value: 6-bit unsigned integer. Values depending on the
setting of the 'E' flag as indicated respectively in Table 4 and setting of the 'E' flag as indicated respectively in Table 4
Table 5. and Table 5.
Reserved: The Reserved field MUST initialized to zero by the sender
and MUST be ignored by the receiver
5.3. Route Projection Options 5.3. Route Projection Options
The RPOs indicate a series of IPv6 addresses that can be compressed The RPOs indicate a series of IPv6 addresses that can be compressed
using the method defined in the "6LoWPAN Routing Header" [RFC8138] using the method defined in the "6LoWPAN Routing Header" [RFC8138]
specification using the address of the Root found in the DODAGID specification using the address of the Root found in the DODAGID
field of DIO messages as Compression Reference. field of DIO messages as Compression Reference.
An RPO indicates a Projected Route that can be a serial Track in full An RPO indicates a Projected Route that can be a serial Track in full
or a segment of a more complex Track. In Non-Storing Mode, multiple or a Segment of a more complex Track. In Non-Storing Mode, multiple
RPO may be placed after a same Target Option to reflect different RPO may be placed after a same Target Option to reflect different
segments originated at this node. The Track is identified by a Segments originated at this node. The Track is identified by a
TrackID that is a Local RPLInstanceID to the Target of the Track. TrackID that is a Local RPLInstanceID to the Target of the Track.
The format of RPOs is as follows: The format of RPOs is as follows:
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 | Option Length |C| Flags | Reserved | | Type | Option Length |C| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TrackID | SegmentID |Segm. Sequence | Seg. Lifetime | | TrackID | SegmentID |Segm. Sequence | Seg. Lifetime |
skipping to change at page 10, line 48 skipping to change at page 11, line 33
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Via Address n . . Via Address n .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Via Information option format (uncompressed form) Figure 4: Route Projection Option format (uncompressed form)
Option Type: 0x0B for VIO, 0x0C for SRVIO (to be confirmed by IANA)
Option Type: 0x0A for VIO, 0x0B for SRVIO (to be confirmed by IANA)
Option Length: In bytes; variable, depending on the number of Via Option Length: In bytes; variable, depending on the number of Via
Addresses. Addresses.
C: 1-bit flag. Set to indicate that the following Via Addresses are C: 1-bit flag. Set to indicate that the following Via Addresses are
expressed as one or more SRH-6LoRH as defined in section 5.1 of expressed as one or more SRH-6LoRH as defined in section 5.1 of
[RFC8138]. Figure 4 illustrates the case where the "C" flag is [RFC8138]. Figure 4 illustrates the case where the "C" flag is
not set, meaning that the Via Addresses are expressed in full 128 not set, meaning that the Via Addresses are expressed in 128 bits.
bits.
TrackID: 8-bit field indicating the topology Instance associated Flags: Reserved. The Flags field MUST initialized to zero by the
with the Track. The tuple (Target Address, TrackID) forms a sender and MUST be ignored by the receiver
unique ID of the Track in the RPL domain.
Track Sequence: 8-bit unsigned integer. The Track Sequence obeys Reserved: The Reserved field MUST initialized to zero by the sender
the operation in section 7.2 of [RPL] and the lollipop starts at and MUST be ignored by the receiver
255. The Track Sequence is set by the Root and incremented each
time the Root refreshes that Track globally. A Track Sequence
that is fresher than the current on deprecates any state for the
Track. A Track Sequence that is current adds to any state that
was learned for that Track Sequence. A RTO with a Track Sequence
that is not as fresh as the current one is ignored.
Track Lifetime: 8-bit unsigned integer. The length of time in TrackID: 8-bit field indicating the topology Instance associated
Lifetime Units (obtained from the Configuration option) that the with the Track. This field carries either a TrackID, such that
Track is usable. The period starts when a new Track Sequence is the tuple (Target Address, TrackID) forms a unique ID of the Track
seen. A value of 255 (0xFF) represents infinity. A value of zero in the RPL domain, or the glocal InstanceID of the main DODAG, in
(0x00) indicates a loss of reachability. A DAO message that which case the RPO adds a route to the main DODAG as an individual
contains a Via Information option with a Path Lifetime of zero for Segment.
a Target is referred as a No-Path (for that Target) in this
document.
SegmentID: 8-bit field that identifies a segment within a Track. A SegmentID: 8-bit field that identifies a Segment within a Track or
Value of 0 is used to signal a serial Track. the main DODAG as indicated by the TrackId field. A Value of 0 is
used to signal a serial path, i.e., made of a single segment.
Segment Sequence: 8-bit unsigned integer. The Segment Sequence Segment Sequence: 8-bit unsigned integer. The Segment Sequence
obeys the operation in section 7.2 of [RPL] and the lollipop obeys the operation in section 7.2 of [RPL] and the lollipop
starts at 255. When the Root of the DODAG needs to update a starts at 255. When the Root of the DODAG needs to refresh or
single segment in a Track, but does not need to modify the rest of update a Segment in a Track, it increments the Segment Sequence
the Track, it increments the Segment Sequence but not the Track individually for that Segment. The Segment information indicated
Sequence. The segment information indicated in the RTO deprecates in the RTO deprecates any state for the Segment indicated by the
any state for the segment indicated by the SegmentID within the SegmentID within the indicated Track and sets up the new
indicated Track and sets up the new information. A RTO with a information. A RTO with a Segment Sequence that is not as fresh
Segment Sequence that is not as fresh as the current one is as the current one is ignored. a RTO for a given target with the
ignored. a RTO for a given target with the same (TrackID, Track same (TrackID, SegmentID, Segment Sequence) indicates a retry; it
Sequence, SegmentID, Segment Sequence) indicates a retry; it MUST MUST NOT change the Segment and MUST be propagated or answered as
NOT change the segment and MUST be propagated or answered as the the first copy.
first copy.
Via Address: The collection of Via Addresses along one segment, Segment Lifetime: 8-bit unsigned integer. The length of time in
Lifetime Units (obtained from the Configuration option) that the
Segment is usable. The period starts when a new Segment Sequence
is seen. A value of 255 (0xFF) represents infinity. A value of
zero (0x00) indicates a loss of reachability. A DAO message that
contains a Via Information option with a Segment Lifetime of zero
for a Target is referred as a No-Path (for that Target) in this
document.
Via Address: The collection of Via Addresses along one Segment,
indicated in the order of the path from the ingress to the egress indicated in the order of the path from the ingress to the egress
nodes. If the "C" flag is set, the fields Via Address 1 .. Via nodes. If the "C" flag is set, the fields Via Address 1 .. Via
Address n in Figure 4 are replaced by one or more of the headers Address n in Figure 4 are replaced by one or more of the headers
illustrated in Fig. 6 of [RFC8138]. More than one SRH-6LoRH is illustrated in Fig. 6 of [RFC8138]. In the case of a VIO, or if
needed if the compression of the addresses change inside the [RFC8138] is turned off, then the Root MUST use only one SRH-
segment and different SRH-6LoRH Types are used. 6LoRH, and the compression is the same for all addresses. If
[RFC8138] is turned on, then the Root SHOULD optimize the size of
the SRVIO; in that case, more than one SRH-6LoRH are needed if the
compression of the addresses change inside the Segment and
different SRH-6LoRH Types are used.
An RPO MUST contain at least one Via Address, and a Via Address MUST An RPO MUST contain at least one Via Address, and a Via Address MUST
NOT be present more than once, otherwise the RPO MUST be ignored. NOT be present more than once, otherwise the RPO MUST be ignored.
5.4. Sibling Information Option 5.4. Sibling Information Option
The Sibling Information Option (SIO) provides indication on siblings The Sibling Information Option (SIO) provides indication on siblings
that could be used by the Root to form Projected Routes. The format that could be used by the Root to form Projected Routes. The format
of SIOs is as follows: of SIOs is as follows:
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 | Option Length |Comp.|B|D|Flags| Opaque | | Type | Option Length |Comp.|B|D|Flags| Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Step of Rank | Sibling Rank | | Step of Rank | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Sibling DODAGID (if 'D' flag not set) . . Sibling DODAGID (if 'D' flag not set) .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Sibling Address . . Sibling Address .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Sibling Information Option Format Figure 5: Sibling Information Option Format
Option Type: 0x0C (to be confirmed by IANA) Option Type: 0x0D (to be confirmed by IANA)
Option Length: In bytes; variable, depending on the number of Via Option Length: In bytes; variable, depending on the number of Via
Addresses. Addresses.
Compression Type: 3-bit unsigned integer. This is the SRH-6LoRH Compression Type: 3-bit unsigned integer. This is the SRH-6LoRH
Type as defined in figure 7 in section 5.1 of [RFC8138] that Type as defined in figure 7 in section 5.1 of [RFC8138] that
corresponds to the compression used for the Sibling Address. corresponds to the compression used for the Sibling Address.
Reserved for Flags: MUST be set to zero by the sender and MUST be Reserved for Flags: MUST be set to zero by the sender and MUST be
ignored by the receiver. ignored by the receiver.
skipping to change at page 13, line 22 skipping to change at page 14, line 13
B: 1-bit flag that is set to indicate that the connectivity to the B: 1-bit flag that is set to indicate that the connectivity to the
sibling is bidirectional and roughly symmetrical. In that case, sibling is bidirectional and roughly symmetrical. In that case,
only one of the siblings may report the SIO for the hop. If 'B' only one of the siblings may report the SIO for the hop. If 'B'
is not set then the SIO only indicates connectivity from the is not set then the SIO only indicates connectivity from the
sibling to this node, and does not provide information on the hop sibling to this node, and does not provide information on the hop
from this node to the sibling. from this node to the sibling.
D: 1-bit flag that is set to indicate that sibling belongs to the D: 1-bit flag that is set to indicate that sibling belongs to the
same DODAG. When not set, the Sibling DODAGID is indicated. same DODAG. When not set, the Sibling DODAGID is indicated.
Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver
Opaque: MAY be used to carry information that the node and the Root Opaque: MAY be used to carry information that the node and the Root
understand, e.g., a particular representation of the Link understand, e.g., a particular representation of the Link
properties such as a proprietary Link Quality Information for properties such as a proprietary Link Quality Information for
packets received from the sibling. An industraial Alliance that packets received from the sibling. An industraial Alliance that
uses RPL for a particular use / environment MAY redefine the use uses RPL for a particular use / environment MAY redefine the use
of this field to fit its needs. of this field to fit its needs.
Step of Rank: 16-bit unsigned integer. This is the Step of Rank Step of Rank: 16-bit unsigned integer. This is the Step of Rank
[RPL] as computed by the Objective Function between this node and [RPL] as computed by the Objective Function between this node and
the sibling. the sibling.
Sibling Rank: 16-bit unsigned integer. When non-zero, this is the Reserved: The Reserved field MUST initialized to zero by the sender
Rank [RPL] as exposed by the sibling in DIO messages. and MUST be ignored by the receiver
Sibling DODAGID: 2 to 16 bytes, the DODAGID of the sibling in a Sibling DODAGID: 2 to 16 bytes, the DODAGID of the sibling in a
[RFC8138] compressed form as indicated by the Compression Type [RFC8138] compressed form as indicated by the Compression Type
field. This field is present when the 'D' flag is not set. field. This field is present when the 'D' flag is not set.
Sibling Address: 2 to 16 bytes, the IPv6 Address of the sibling in a Sibling Address: 2 to 16 bytes, the IPv6 Address of the sibling in a
[RFC8138] compressed form as indicated by the Compression Type [RFC8138] compressed form as indicated by the Compression Type
field. field.
An SIO MAY be immediately followed by a DAG Metric Container. In An SIO MAY be immediately followed by a DAG Metric Container. In
skipping to change at page 14, line 24 skipping to change at page 15, line 15
A P-DAO is sent from a global address of the Root to a global address A P-DAO is sent from a global address of the Root to a global address
of the recipient, and MUST be confirmed by a DAO-ACK, which is sent of the recipient, and MUST be confirmed by a DAO-ACK, which is sent
back to a global address of the Root. back to a global address of the Root.
A P-DAO message MUST contain exactly one RTO and either one VIO or A P-DAO message MUST contain exactly one RTO and either one VIO or
one or more SRVIOs following it. There can be at most one such one or more SRVIOs following it. There can be at most one such
sequence of RTOs and then RPOs. sequence of RTOs and then RPOs.
Like a classical DAO message, a P-DAO causes a change of state only Like a classical DAO message, a P-DAO causes a change of state only
if it is "new" per section 9.2.2. "Generation of DAO Messages" of if it is "new" per section 9.2.2. "Generation of DAO Messages" of
the RPL specification [RPL]; this is determined using the Track the RPL specification [RPL]; this is determined using the Segment
Sequence and the Segment Sequence information from the RPO as opposed Sequence information from the RPO as opposed to the Path Sequence
to the Path Sequence from a TIO. Also, a Path Lifetime of 0 in an from a TIO. Also, a Segment Lifetime of 0 in an RPO indicates that
RPO indicates that a route is to be removed. the projected route associated to the Segment is to be removed.
There are two kinds of operation for the Projected Routes, the There are two kinds of operation for the Projected Routes, the
Storing Mode and the Non-Storing Mode. Storing Mode and the Non-Storing Mode.
* The Non-Storing Mode is discussed in Section 6.1. It uses an * The Non-Storing Mode is discussed in Section 6.3. It uses an
SRVIO that carries a list of Via Addresses to be used as a source- SRVIO that carries a list of Via Addresses to be used as a source-
routed path to the Target. The recipient of the P-DAO is the routed path to the Target. The recipient of the P-DAO is the
ingress router of the source-routed path. Upon a Non-Storing Mode ingress router of the source-routed path. Upon a Non-Storing Mode
P-DAO, the ingress router installs a source-routed state to the P-DAO, the ingress router installs a source-routed state to the
Target and replies to the Root directly with a DAO-ACK message. Target and replies to the Root directly with a DAO-ACK message.
* The Storing Mode is discussed in Section 6.2. It uses a VIO with * The Storing Mode is discussed in Section 6.4. It uses a VIO with
one Via Address per consecutive hop, from the ingress to the one Via Address per consecutive hop, from the ingress to the
egress of the path, including the list of all intermediate routers egress of the path, including the list of all intermediate routers
in the data path order. The Via Addresses indicate the routers in in the data path order. The Via Addresses indicate the routers in
which the routing state to the Target have to be installed via the which the routing state to the Target have to be installed via the
next Via Address in the VIO. In normal operations, the P-DAO is next Via Address in the VIO. In normal operations, the P-DAO is
propagated along the chain of Via Routers from the egress router propagated along the chain of Via Routers from the egress router
of the path till the ingress one, which confirms the installation of the path till the ingress one, which confirms the installation
to the Root with a DAO-ACK message. Note that the Root may be the to the Root with a DAO-ACK message. Note that the Root may be the
ingress and it may be the egress of the path, that it can also be ingress and it may be the egress of the path, that it can also be
neither but it cannot be both. neither but it cannot be both.
skipping to change at page 15, line 15 skipping to change at page 16, line 4
In case of a forwarding error along a Projected Route, an ICMP error In case of a forwarding error along a Projected Route, an ICMP error
is sent to the Root with a new Code "Error in Projected Route" (See is sent to the Root with a new Code "Error in Projected Route" (See
Section 8.9). The Root can then modify or remove the Projected Section 8.9). The Root can then modify or remove the Projected
Route. The "Error in Projected Route" message has the same format as Route. The "Error in Projected Route" message has the same format as
the "Destination Unreachable Message", as specified in RFC 4443 the "Destination Unreachable Message", as specified in RFC 4443
[RFC4443]. The portion of the invoking packet that is sent back in [RFC4443]. The portion of the invoking packet that is sent back in
the ICMP message SHOULD record at least up to the routing header if the ICMP message SHOULD record at least up to the routing header if
one is present, and the routing header SHOULD be consumed by this one is present, and the routing header SHOULD be consumed by this
node so that the destination in the IPv6 header is the next hop that node so that the destination in the IPv6 header is the next hop that
this node could not reach. if a 6LoWPAN Routing Header (6LoRH) this node could not reach. if a 6LoWPAN Routing Header (6LoRH)
[RFC8138] is used to carry the IPv6 routing information in the outter [RFC8138] is used to carry the IPv6 routing information in the outter
header then that whole 6LoRH information SHOULD be present in the header then that whole 6LoRH information SHOULD be present in the
ICMP message. The sender and exact operation depend on the Mode and ICMP message. The sender and exact operation depend on the Mode and
is described in Section 6.1 and Section 6.2 respectively. is described in Section 6.3 and Section 6.4 respectively.
6.1. Non-Storing Mode Projected Route 6.1. Requesting a Track
A Node is free to ask the Root for a new Track with a PDR message,
for a duration indicated in a Requested Lifetime field. Upon that
Request, the Root install the necessary Segments and answers with a
PDR-ACK indicated the granted Track Lifetime. When the Track
Lifetime returned in the PDR-ACK is close to elapse, the resquesting
Node needs to resend a PDR using the TrackID in the PDR-ACK to get
the lifetime of the Track prolonged, else the Track will time out and
the Root will tear down the whole structure.
The Segment Lifetime in the P-DAO messages does not need to be
aligned to the Requested Lifetime in the PDR, or between P-DAO
messages for different Segments. The Root may use shorter lifetimes
for the Segments and renew them faster than the Track is, or longer
lifetimes in which case it will need to tear down the Segments if the
Track is not renewed.
The Root is free to install which ever Segments it wants, and change
them overtime, to serve the Track as needed, without notifying the
resquesting Node. If the Track fails and cannot be reestablished,
the Root notifies the resquesting Node asynchronously with a PDR-ACK
with a Track Lifetime of 0, indicating that the Track has failed, and
a PDR-ACK Status indicating the reason of the fault.
All the Segments MUST be of a same mode, either Storing or Non-
Storing. All the Segments MUST be created with the same TrackId and
Target in the P-DAO.
6.2. Routing over a Track
Sending a packet over a Track implies the addition of a RPI to
indicate the Track, in association with the IPv6 destination. In
case of a Non-Storing Mode Projected Route, a Source Routing Header
is needed as well.
The Destination IPv6 Address of a packet that is place in a Track
MUST be that of the Target of Track. The outer header of the packet
MUST contain an RPI that indicates the TrackId as RPL Instance ID.
If the Track Ingress is the originator of the packet and the Track
Egress (i.e., the Target) is the destination of the packet, there is
no need of an encapsulation. Else, i.e., if the Track Ingress is
forwarding a packet into the Track, or if the the final destination
is reached via is not the Target, but reached over the Track via the
Track Egress, then an IP-in-IP encapsulation is needed.
6.3. Non-Storing Mode Projected Route
As illustrated in Figure 6, a P-DAO that carries an SRVIO enables the As illustrated in Figure 6, a P-DAO that carries an SRVIO enables the
Root to install a source-routed path towards a Target in any Root to install a source-routed path towards a Target in any
particular router; with this path information the router can add a particular router; with this path information the router can add a
source routed header reflecting the Projected Route to any packet for source routed header reflecting the Projected Route to any packet for
which the current destination either is the said Target or can be which the current destination either is the said Target or can be
reached via the Target. reached via the Target.
------+--------- ------+---------
| Internet | Internet
skipping to change at page 16, line 20 skipping to change at page 18, line 9
Route does not have a connected route (a direct adjacency) to the Route does not have a connected route (a direct adjacency) to the
next soure routed hop and fails to locate it as a neighbor or a next soure routed hop and fails to locate it as a neighbor or a
neighbor of a neighbor, then it MUST ensure that it has another neighbor of a neighbor, then it MUST ensure that it has another
Projected Route to the next loose hop under the control of the same Projected Route to the next loose hop under the control of the same
route computation system, otherwise the P-DAO is rejected. route computation system, otherwise the P-DAO is rejected.
When forwarding a packet to a destination for which the router When forwarding a packet to a destination for which the router
determines that routing happens via the Target, the router inserts determines that routing happens via the Target, the router inserts
the source routing header in the packet to reach the Target. In the source routing header in the packet to reach the Target. In
order to add a source-routing header, the router encapsulates the order to add a source-routing header, the router encapsulates the
packet with an IP-in-IP header and a non-storing mode source routing packet with an IP-in-IP header and a Non-Storing Mode source routing
header (SRH) [RFC6554]. In the uncompressed form the source of the header (SRH) [RFC6554]. In the uncompressed form the source of the
packet would be self, the destination would be the first Via Address packet would be self, the destination would be the first Via Address
in the SRVIO, and the SRH would contain the list of the remaining Via in the SRVIO, and the SRH would contain the list of the remaining Via
Addresses and then the Target. Addresses and then the Target.
In the case of a loose source-routed path, there MUST be either a In the case of a loose source-routed path, there MUST be either a
neighbor that is adjacent to the loose next hop, on which case the neighbor that is adjacent to the loose next hop, on which case the
packet is forwarded to that neighbor, or a source-routed path to the packet is forwarded to that neighbor, or a source-routed path to the
loose next hop; in the latter case, another encapsulation takes place loose next hop; in the latter case, another encapsulation takes place
and the process possibly recurses; otherwise the packet is dropped. and the process possibly recurses; otherwise the packet is dropped.
skipping to change at page 17, line 5 skipping to change at page 18, line 37
In case of a forwarding error along a Source Route path, the node In case of a forwarding error along a Source Route path, the node
that fails to forward SHOULD send an ICMP error with a code "Error in that fails to forward SHOULD send an ICMP error with a code "Error in
Source Routing Header" back to the source of the packet, as described Source Routing Header" back to the source of the packet, as described
in section 11.2.2.3. of [RPL]. Upon this message, the encapsulating in section 11.2.2.3. of [RPL]. Upon this message, the encapsulating
node SHOULD stop using the source route path for a period of time and node SHOULD stop using the source route path for a period of time and
it SHOULD send an ICMP message with a Code "Error in Projected Route" it SHOULD send an ICMP message with a Code "Error in Projected Route"
to the Root. Failure to follow these steps may result in packet loss to the Root. Failure to follow these steps may result in packet loss
and wasted resources along the source route path that is broken. and wasted resources along the source route path that is broken.
6.2. Storing-Mode Projected Route 6.4. Storing-Mode Projected Route
As illustrated in Figure 7, the Storing Mode route projection is used As illustrated in Figure 7, the Storing Mode route projection is used
by the Root to install a routing state towards a Target in the by the Root to install a routing state towards a Target in the
routers along a segment between an ingress and an egress router; this routers along a Segment between an ingress and an egress router; this
enables the routers to forward along that segment any packet for enables the routers to forward along that Segment any packet for
which the next loose hop is the said Target, for Instance a loose which the next loose hop is the said Target, for Instance a loose
source routed packet for which the next loose hop is the Target, or a source routed packet for which the next loose hop is the Target, or a
packet for which the router has a routing state to the final packet for which the router has a routing state to the final
destination via the Target. destination via the Target.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
skipping to change at page 17, line 35 skipping to change at page 19, line 24
o o o o o o o o o | ^ | Projected . o o o o o o o o o | ^ | Projected .
o o o o o o o o o o | | DAO | Route . o o o o o o o o o o | | DAO | Route .
o o o o o o o o o | ^ | . o o o o o o o o o | ^ | .
o o o o o o o o v | DAO v . o o o o o o o o v | DAO v .
o o LLN o o o | o o LLN o o o |
o o o o o Loose Source Route Path | o o o o o Loose Source Route Path |
o o o o From Root To Destination v o o o o From Root To Destination v
Figure 7: Projecting a route Figure 7: Projecting a route
In order to install the relevant routing state along the segment In order to install the relevant routing state along the Segment
between an ingress and an egress routers, the Root sends a unicast between an ingress and an egress routers, the Root sends a unicast
P-DAO message to the egress router of the routing segment that must P-DAO message to the egress router of the routing Segment that must
be installed. The P-DAO message contains the ordered list of hops be installed. The P-DAO message contains the ordered list of hops
along the segment as a direct sequence of Via Information options along the Segment as a direct sequence of Via Information options
that are preceded by one or more RPL Target options to which they that are preceded by one or more RPL Target options to which they
relate. Each Via Information option contains a Path Lifetime for relate. Each Via Information option contains a Segment Lifetime for
which the state is to be maintained. which the state is to be maintained.
The Root sends the P-DAO directly to the egress node of the segment. The Root sends the P-DAO directly to the egress node of the Segment.
In that P-DAO, the destination IP address matches the Via Address in In that P-DAO, the destination IP address matches the Via Address in
the last VIO. This is how the egress recognizes its role. In a the last VIO. This is how the egress recognizes its role. In a
similar fashion, the ingress node recognizes its role as it matches similar fashion, the ingress node recognizes its role as it matches
Via Address in the first VIO. Via Address in the first VIO.
The egress node of the segment is the only node in the path that does The egress node of the Segment is the only node in the path that does
not install a route in response to the P-DAO; it is expected to be not install a route in response to the P-DAO; it is expected to be
already able to route to the Target(s) on its own. It may either be already able to route to the Target(s) on its own. It may either be
the Target, or may have some existing information to reach the the Target, or may have some existing information to reach the
Target(s), such as a connected route or an already installed Target(s), such as a connected route or an already installed
Projected Route. If one of the Targets cannot be located, the node Projected Route. If one of the Targets cannot be located, the node
MUST answer to the Root with a negative DAO-ACK listing the Target(s) MUST answer to the Root with a negative DAO-ACK listing the Target(s)
that could not be located (suggested status 10 to be confirmed by that could not be located (suggested status 10 to be confirmed by
IANA). IANA).
If the egress node can reach all the Targets, then it forwards the If the egress node can reach all the Targets, then it forwards the
P-DAO with unchanged content to its loose predecessor in the segment P-DAO with unchanged content to its loose predecessor in the Segment
as indicated in the list of Via Information options, and recursively as indicated in the list of Via Information options, and recursively
the message is propagated unchanged along the sequence of routers the message is propagated unchanged along the sequence of routers
indicated in the P-DAO, but in the reverse order, from egress to indicated in the P-DAO, but in the reverse order, from egress to
ingress. ingress.
The address of the predecessor to be used as destination of the The address of the predecessor to be used as destination of the
propagated DAO message is found in the Via Information option the propagated DAO message is found in the Via Information option the
precedes the one that contain the address of the propagating node, precedes the one that contain the address of the propagating node,
which is used as source of the packet. which is used as source of the packet.
Upon receiving a propagated DAO, an intermediate router as well as Upon receiving a propagated DAO, an intermediate router as well as
the ingress router install a route towards the DAO Target(s) via its the ingress router install a route towards the DAO Target(s) via its
successor in the P-DAO; the router locates the VIO that contains its successor in the P-DAO; the router locates the VIO that contains its
address, and uses as next hop the address found in the Via Address address, and uses as next hop the address found in the Via Address
field in the following VIO. The router MAY install additional routes field in the following VIO. The router MAY install additional routes
towards the addresses that are located in VIOs that are after the towards the addresses that are located in VIOs that are after the
next one, if any, but in case of a conflict or a lack of resource, a next one, if any, but in case of a conflict or a lack of resource, a
route to a Target installed by the Root has precedence. route to a Target installed by the Root has precedence.
The process recurses till the P-DAO is propagated to ingress router The process recurses till the P-DAO is propagated to ingress router
of the segment, which answers with a DAO-ACK to the Root. of the Segment, which answers with a DAO-ACK to the Root.
Also, the path indicated in a P-DAO may be loose, in which case the Also, the path indicated in a P-DAO may be loose, in which case the
reachability to the next hop has to be asserted. Each router along reachability to the next hop has to be asserted. Each router along
the path indicated in a P-DAO is expected to be able to reach its the path indicated in a P-DAO is expected to be able to reach its
successor, either with a connected route (direct neighbor), or by successor, either with a connected route (direct neighbor), or by
routing, for Instance following a route installed previously by a DAO routing, for Instance following a route installed previously by a DAO
or a P-DAO message. If that route is not connected then a recursive or a P-DAO message. If that route is not connected then a recursive
lookup may take place at packet forwarding time to find the next hop lookup may take place at packet forwarding time to find the next hop
to reach the Target(s). If it does not and cannot reach the next to reach the Target(s). If it does not and cannot reach the next
router in the P-DAO, the router MUST answer to the Root with a router in the P-DAO, the router MUST answer to the Root with a
negative DAO-ACK indicating the successor that is unreachable negative DAO-ACK indicating the successor that is unreachable
(suggested status 11 to be confirmed by IANA). (suggested status 11 to be confirmed by IANA).
A Path Lifetime of 0 in a Via Information option is used to clean up A Segment Lifetime of 0 in a Via Information option is used to clean
the state. The P-DAO is forwarded as described above, but the DAO is up the state. The P-DAO is forwarded as described above, but the DAO
interpreted as a No-Path DAO and results in cleaning up existing is interpreted as a No-Path DAO and results in cleaning up existing
state as opposed to refreshing an existing one or installing a new state as opposed to refreshing an existing one or installing a new
one. one.
In case of a forwarding error along a Storing Mode Projected Route, In case of a forwarding error along a Storing Mode Projected Route,
the node that fails to forward SHOULD send an ICMP error with a code the node that fails to forward SHOULD send an ICMP error with a code
"Error in Projected Route" to the Root. Failure to do so may result "Error in Projected Route" to the Root. Failure to do so may result
in packet loss and wasted resources along the Projected Route that is in packet loss and wasted resources along the Projected Route that is
broken. broken.
7. Security Considerations 7. Security Considerations
skipping to change at page 20, line 17 skipping to change at page 22, line 5
+=======+======================================+===============+ +=======+======================================+===============+
| 0x0B | Via Information option | This document | | 0x0B | Via Information option | This document |
+-------+--------------------------------------+---------------+ +-------+--------------------------------------+---------------+
| 0x0C | Source-Routed Via Information option | This document | | 0x0C | Source-Routed Via Information option | This document |
+-------+--------------------------------------+---------------+ +-------+--------------------------------------+---------------+
| 0x0D | Sibling Information option | This document | | 0x0D | Sibling Information option | This document |
+-------+--------------------------------------+---------------+ +-------+--------------------------------------+---------------+
Table 2: RPL Control Message Options Table 2: RPL Control Message Options
8.3. New SubRegistry for the Projected DAO Request (PDR) Flags 8.3. SubRegistry for the Projected DAO Request Flags
IANA is required to create a registry for the 8-bit Projected DAO IANA is required to create a registry for the 8-bit Projected DAO
Request (PDR) Flags field. Each bit is tracked with the following Request (PDR) Flags field. Each bit is tracked with the following
qualities: qualities:
* Bit number (counting from bit 0 as the most significant bit) * Bit number (counting from bit 0 as the most significant bit)
* Capability description * Capability description
* Reference * Reference
skipping to change at page 20, line 43 skipping to change at page 22, line 31
| Bit number | Capability description | Reference | | Bit number | Capability description | Reference |
+============+========================+===============+ +============+========================+===============+
| 0 | PDR-ACK request (K) | This document | | 0 | PDR-ACK request (K) | This document |
+------------+------------------------+---------------+ +------------+------------------------+---------------+
| 1 | Requested path should | This document | | 1 | Requested path should | This document |
| | be redundant (R) | | | | be redundant (R) | |
+------------+------------------------+---------------+ +------------+------------------------+---------------+
Table 3: Initial PDR Flags Table 3: Initial PDR Flags
8.4. New SubRegistry for the PDR-ACK Flags 8.4. SubRegistry for the PDR-ACK Flags
IANA is required to create an subregistry for the 8-bit PDR-ACK Flags IANA is required to create an subregistry for the 8-bit PDR-ACK Flags
field. Each bit is tracked with the following qualities: field. Each bit is tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit) * Bit number (counting from bit 0 as the most significant bit)
* Capability description * Capability description
* Reference * Reference
Registration procedure is "Standards Action" [RFC8126]. No bit is Registration procedure is "Standards Action" [RFC8126]. No bit is
currently defined for the PDR-ACK Flags. currently defined for the PDR-ACK Flags.
8.5. New Subregistry for the PDR-ACK Acceptance Status values 8.5. Subregistry for the PDR-ACK Acceptance Status Values
IANA is requested to create a new subregistry for the PDR-ACK IANA is requested to create a Subregistry for the PDR-ACK Acceptance
Acceptance Status values. Status values.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 4: * Initial allocation is as indicated in Table 4:
+-------+------------------------+---------------+ +-------+------------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+------------------------+---------------+ +-------+------------------------+---------------+
| 0 | Unqualified acceptance | This document | | 0 | Unqualified acceptance | This document |
+-------+------------------------+---------------+ +-------+------------------------+---------------+
Table 4: Acceptance values of the PDR-ACK Status Table 4: Acceptance values of the PDR-ACK Status
8.6. New Subregistry for the PDR-ACK Rejection Status values 8.6. Subregistry for the PDR-ACK Rejection Status Values
IANA is requested to create a new subregistry for the PDR-ACK IANA is requested to create a Subregistry for the PDR-ACK Rejection
Rejection Status values. Status values.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 5: * Initial allocation is as indicated in Table 5:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| 0 | Unqualified rejection | This document | | 0 | Unqualified rejection | This document |
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
Table 5: Rejection values of the PDR-ACK Status Table 5: Rejection values of the PDR-ACK Status
8.7. New SubRegistry for the Route Projection Options (RPO) Flags 8.7. SubRegistry for the Route Projection Options Flags
IANA is requested to create a new subregistry for the 5-bit Route IANA is requested to create a Subregistry for the 5-bit Route
Projection Options (RPO) Flags field. Each bit is tracked with the Projection Options (RPO) Flags field. Each bit is tracked with the
following qualities: following qualities:
* Bit number (counting from bit 0 as the most significant bit) * Bit number (counting from bit 0 as the most significant bit)
* Capability description * Capability description
* Reference * Reference
Registration procedure is "Standards Action" [RFC8126]. No bit is Registration procedure is "Standards Action" [RFC8126]. No bit is
currently defined for the Route Projection Options (RPO) Flags. currently defined for the Route Projection Options (RPO) Flags.
8.8. New SubRegistry for the Sibling Information Option (SIO) Flags 8.8. SubRegistry for the Sibling Information Option Flags
IANA is required to create a registry for the 5-bit Sibling IANA is required to create a registry for the 5-bit Sibling
Information Option (SIO) Flags field. Each bit is tracked with the Information Option (SIO) Flags field. Each bit is tracked with the
following qualities: following qualities:
* Bit number (counting from bit 0 as the most significant bit) * Bit number (counting from bit 0 as the most significant bit)
* Capability description * Capability description
* Reference * Reference
skipping to change at page 24, line 8 skipping to change at page 25, line 48
[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
J. Martocci, "Reactive Discovery of Point-to-Point Routes J. Martocci, "Reactive Discovery of Point-to-Point Routes
in Low-Power and Lossy Networks", RFC 6997, in Low-Power and Lossy Networks", RFC 6997,
DOI 10.17487/RFC6997, August 2013, DOI 10.17487/RFC6997, August 2013,
<https://www.rfc-editor.org/info/rfc6997>. <https://www.rfc-editor.org/info/rfc6997>.
[6TiSCH-ARCHI] [6TiSCH-ARCHI]
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", Work in Progress, Internet-Draft, of IEEE 802.15.4", Work in Progress, Internet-Draft,
draft-ietf-6tisch-architecture-29, August 27, 2020, draft-ietf-6tisch-architecture-29, 27 August 2020,
<https://tools.ietf.org/html/draft-ietf-6tisch- <https://tools.ietf.org/html/draft-ietf-6tisch-
architecture-29>. architecture-29>.
[RAW-ARCHI] [RAW-ARCHI]
Thubert, P., Papadopoulos, G., and R. Buddenberg, Thubert, P., Papadopoulos, G., and R. Buddenberg,
"Reliable and Available Wireless Architecture/Framework", "Reliable and Available Wireless Architecture/Framework",
Work in Progress, Internet-Draft, draft-pthubert-raw- Work in Progress, Internet-Draft, draft-pthubert-raw-
architecture-04, July 6, 2020, architecture-04, 6 July 2020,
<https://tools.ietf.org/html/draft-pthubert-raw- <https://tools.ietf.org/html/draft-pthubert-raw-
architecture-04>. architecture-04>.
[TURN-ON_RFC8138] [TURN-ON_RFC8138]
Thubert, P. and L. Zhao, "Configuration option for RFC Thubert, P. and L. Zhao, "Configuration option for RFC
8138", Work in Progress, Internet-Draft, draft-thubert- 8138", Work in Progress, Internet-Draft, draft-thubert-
roll-turnon-rfc8138-03, July 8, 2019, roll-turnon-rfc8138-03, 8 July 2019,
<https://tools.ietf.org/html/draft-thubert-roll-turnon- <https://tools.ietf.org/html/draft-thubert-roll-turnon-
rfc8138-03>. rfc8138-03>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655, "Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019, DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>. <https://www.rfc-editor.org/info/rfc8655>.
[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch", Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016, RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>. <https://www.rfc-editor.org/info/rfc8025>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network "IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>. April 2017, <https://www.rfc-editor.org/info/rfc8138>.
[USEofRPLinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", Work in
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-40,
25 June 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-40>.
[PCE] IETF, "Path Computation Element", [PCE] IETF, "Path Computation Element",
<https://datatracker.ietf.org/doc/charter-ietf-pce/>. <https://datatracker.ietf.org/doc/charter-ietf-pce/>.
Appendix A. Applications Appendix A. Applications
A.1. Loose Source Routing in Non-storing Mode A.1. Loose Source Routing
A RPL implementation operating in a very constrained LLN typically A RPL implementation operating in a very constrained LLN typically
uses the Non-Storing Mode of Operation as represented in Figure 8. uses the Non-Storing Mode of Operation as represented in Figure 8.
In that mode, a RPL node indicates a parent-child relationship to the In that mode, a RPL node indicates a parent-child relationship to the
Root, using a Destination Advertisement Object (DAO) that is unicast Root, using a Destination Advertisement Object (DAO) that is unicast
from the node directly to the Root, and the Root typically builds a from the node directly to the Root, and the Root typically builds a
source routed path to a destination down the DODAG by recursively source routed path to a destination down the DODAG by recursively
concatenating this information. concatenating this information.
------+--------- ------+---------
skipping to change at page 25, line 30 skipping to change at page 27, line 30
+-----+ ^ | | +-----+ ^ | |
| | DAO | ACK | | | DAO | ACK |
o o o o | | | Strict o o o o | | | Strict
o o o o o o o o o | | | Source o o o o o o o o o | | | Source
o o o o o o o o o o | | | Route o o o o o o o o o o | | | Route
o o o o o o o o o | | | o o o o o o o o o | | |
o o o o o o o o | v v o o o o o o o o | v v
o o o o o o o o
LLN LLN
Figure 8: RPL non-storing mode of operation Figure 8: RPL Non-Storing Mode of operation
Based on the parent-children relationships expressed in the non- Based on the parent-children relationships expressed in the non-
storing DAO messages,the Root possesses topological information about storing DAO messages,the Root possesses topological information about
the whole network, though this information is limited to the the whole network, though this information is limited to the
structure of the DODAG for which it is the destination. A packet structure of the DODAG for which it is the destination. A packet
that is generated within the domain will always reach the Root, which that is generated within the domain will always reach the Root, which
can then apply a source routing information to reach the destination can then apply a source routing information to reach the destination
if the destination is also in the DODAG. Similarly, a packet coming if the destination is also in the DODAG. Similarly, a packet coming
from the outside of the domain for a destination that is expected to from the outside of the domain for a destination that is expected to
be in a RPL domain reaches the Root. be in a RPL domain reaches the Root.
skipping to change at page 26, line 19 skipping to change at page 28, line 19
would allow to make the source routing operation loose as opposed to would allow to make the source routing operation loose as opposed to
strict, and save packet size. Limiting the packet size is directly strict, and save packet size. Limiting the packet size is directly
beneficial to the energy budget, but, mostly, it reduces the chances beneficial to the energy budget, but, mostly, it reduces the chances
of frame loss and/or packet fragmentation, which is highly of frame loss and/or packet fragmentation, which is highly
detrimental to the LLN operation. Because the capability to store a detrimental to the LLN operation. Because the capability to store a
routing state in every node is limited, the decision of which route routing state in every node is limited, the decision of which route
is installed where can only be optimized with a global knowledge of is installed where can only be optimized with a global knowledge of
the system, a knowledge that the Root or an associated PCE may the system, a knowledge that the Root or an associated PCE may
possess by means that are outside of the scope of this specification. possess by means that are outside of the scope of this specification.
This specification enables to store source-routed or storing mode This specification enables to store source-routed or Storing Mode
state in intermediate routers, which enables to limit the excursion state in intermediate routers, which enables to limit the excursion
of the source route headers in deep networks. Once a P-DAO exchange of the source route headers in deep networks. Once a P-DAO exchange
has taken place for a given Target, if the Root operates in non has taken place for a given Target, if the Root operates in non
storing mode, then it may elide the sequence of routers that is Storing Mode, then it may elide the sequence of routers that is
installed in the network from its source route headers to destination installed in the network from its source route headers to destination
that are reachable via that Target, and the source route headers that are reachable via that Target, and the source route headers
effectively become loose. effectively become loose.
A.2. Transversal Routes in storing and non-storing modes A.2. Transversal Routes
RPL is optimized for Point-to-Multipoint (P2MP) and Multipoint-to- RPL is optimized for Point-to-Multipoint (P2MP) and Multipoint-to-
Point (MP2P), whereby routes are always installed along the RPL DODAG Point (MP2P), whereby routes are always installed along the RPL DODAG
respectively from and towards the DODAG Root. Transversal Peer to respectively from and towards the DODAG Root. Transversal Peer to
Peer (P2P) routes in a RPL network will generally suffer from some Peer (P2P) routes in a RPL network will generally suffer from some
elongated (stretched) path versus the best possible path, since elongated (stretched) path versus the best possible path, since
routing between 2 nodes always happens via a common parent, as routing between 2 nodes always happens via a common parent, as
illustrated in Figure 9: illustrated in Figure 9:
* in non-storing mode, all packets routed within the DODAG flow all * In Storing Mode, unless the destination is a child of the source,
the way up to the Root of the DODAG. If the destination is in the
same DODAG, the Root must encapsulate the packet to place a
Routing Header that has the strict source route information down
the DODAG to the destination. This will be the case even if the
destination is relatively close to the source and the Root is
relatively far off.
* In storing mode, unless the destination is a child of the source,
the packets will follow the default route up the DODAG as well. the packets will follow the default route up the DODAG as well.
If the destination is in the same DODAG, they will eventually If the destination is in the same DODAG, they will eventually
reach a common parent that has a route to the destination; at reach a common parent that has a route to the destination; at
worse, the common parent may also be the Root. From that common worse, the common parent may also be the Root. From that common
parent, the packet will follow a path down the DODAG that is parent, the packet will follow a path down the DODAG that is
optimized for the Objective Function that was used to build the optimized for the Objective Function that was used to build the
DODAG. DODAG.
* in Non-Storing Mode, all packets routed within the DODAG flow all
the way up to the Root of the DODAG. If the destination is in the
same DODAG, the Root must encapsulate the packet to place a
Routing Header that has the strict source route information down
the DODAG to the destination. This will be the case even if the
destination is relatively close to the source and the Root is
relatively far off.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
X X
^ v o o ^ v o o
^ o o v o o o o o ^ o o v o o o o o
^ o o o v o o o o o ^ o o o v o o o o o
^ o o v o o o o o ^ o o v o o o o o
S o o o D o o o S o o o D o o o
o o o o o o o o
LLN LLN
Figure 9: Routing Stretch between S and D via common parent X Figure 9: Routing Stretch between S and D via common parent X
It results that it is often beneficial to enable transversal P2P It results that it is often beneficial to enable transversal P2P
routes, either if the RPL route presents a stretch from shortest routes, either if the RPL route presents a stretch from shortest
path, or if the new route is engineered with a different objective. path, or if the new route is engineered with a different objective,
For that reason, earlier work at the IETF introduced the "Reactive and that it is even more critical in Non-Storing Mode than it is in
Discovery of Point-to-Point Routes in Low Power and Lossy Networks" Storing Mode, because the routing stretch is wider. For that reason,
[RFC6997], which specifies a distributed method for establishing earlier work at the IETF introduced the "Reactive Discovery of
optimized P2P routes. This draft proposes an alternate based on a Point-to-Point Routes in Low Power and Lossy Networks" [RFC6997],
centralized route computation. which specifies a distributed method for establishing optimized P2P
routes. This draft proposes an alternate based on a centralized
route computation.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
| |
o o o o o o o o
o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o
S>>A>>>B>>C>>>D o o o S>>A>>>B>>C>>>D o o o
o o o o o o o o
LLN LLN
Figure 10: Projected Transversal Route Figure 10: Projected Transversal Route
This specification enables to store source-routed or storing mode This specification enables to store source-routed or Storing Mode
state in intermediate routers, which enables to limit the stretch of state in intermediate routers, which enables to limit the stretch of
a P2P route and maintain the characteristics within a given SLA. An a P2P route and maintain the characteristics within a given SLA. An
example of service using this mechanism oculd be a control loop that example of service using this mechanism oculd be a control loop that
would be installed in a network that uses classical RPL for would be installed in a network that uses classical RPL for
asynchronous data collection. In that case, the P2P path may be asynchronous data collection. In that case, the P2P path may be
installed in a different RPL Instance, with a different objective installed in a different RPL Instance, with a different objective
function. function.
Appendix B. Examples Appendix B. Examples
B.1. Using storing mode P-DAO in non-storing mode MOP B.1. Using Storing Mode P-DAO in Non-Storing Mode MOP
In non-storing mode, the DAG Root maintains the knowledge of the In Non-Storing Mode, the DAG Root maintains the knowledge of the
whole DODAG topology, so when both the source and the destination of whole DODAG topology, so when both the source and the destination of
a packet are in the DODAG, the Root can determine the common parent a packet are in the DODAG, the Root can determine the common parent
that would have been used in storing mode, and thus the list of nodes that would have been used in Storing Mode, and thus the list of nodes
in the path between the common parent and the destination. For in the path between the common parent and the destination. For
Instance in the diagram shown in Figure 11, if the source is node 41 Instance in the diagram shown in Figure 11, if the source is node 41
and the destination is node 52, then the common parent is node 22. and the destination is node 52, then the common parent is node 22.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
skipping to change at page 29, line 28 skipping to change at page 31, line 28
o 31 o 32 o o o 35 o 31 o 32 o o o 35
/ / | \ | \ / / | \ | \
o 41 o 42 o o o 45 o 46 o 41 o 42 o o o 45 o 46
| | | | \ | | | | | \ |
o 51 o 52 o 53 o o 55 o 56 o 51 o 52 o 53 o o 55 o 56
LLN LLN
Figure 11: Example DODAG forming a logical tree topology Figure 11: Example DODAG forming a logical tree topology
With this draft, the Root can install a storing mode routing states With this draft, the Root can install a Storing Mode routing states
along a segment that is either from itself to the destination, or along a Segment that is either from itself to the destination, or
from one or more common parents for a particular source/destination from one or more common parents for a particular source/destination
pair towards that destination (in this particular example, this would pair towards that destination (in this particular example, this would
be the segment made of nodes 22, 32, 42). be the Segment made of nodes 22, 32, 42).
In the example below, say that there is a lot of traffic to nodes 55 In the example below, say that there is a lot of traffic to nodes 55
and 56 and the Root decides to reduce the size of routing headers to and 56 and the Root decides to reduce the size of routing headers to
those destinations. The Root can first send a DAO to node 45 those destinations. The Root can first send a DAO to node 45
indicating Target 55 and a Via segment (35, 45), as well as another indicating Target 55 and a Via Segment (35, 45), as well as another
DAO to node 46 indicating Target 56 and a Via segment (35, 46). This DAO to node 46 indicating Target 56 and a Via Segment (35, 46). This
will save one entry in the routing header on both sides. The Root will save one entry in the routing header on both sides. The Root
may then send a DAO to node 35 indicating Targets 55 and 56 a Via may then send a DAO to node 35 indicating Targets 55 and 56 a Via
segment (13, 24, 35) to fully optimize that path. Segment (13, 24, 35) to fully optimize that path.
Alternatively, the Root may send a DAO to node 45 indicating Target Alternatively, the Root may send a DAO to node 45 indicating Target
55 and a Via segment (13, 24, 35, 45) and then a DAO to node 46 55 and a Via Segment (13, 24, 35, 45) and then a DAO to node 46
indicating Target 56 and a Via segment (13, 24, 35, 46), indicating indicating Target 56 and a Via Segment (13, 24, 35, 46), indicating
the same DAO Sequence. the same DAO Sequence.
B.2. Projecting a storing-mode transversal route B.2. Projecting a storing-mode transversal route
In this example, say that a PCE determines that a path must be In this example, say that a PCE determines that a path must be
installed between node S and node D via routers A, B and C, in order installed between node S and node D via routers A, B and C, in order
to serve the needs of a particular application. to serve the needs of a particular application.
The Root sends a P-DAO with a Target option indicating the The Root sends a P-DAO with a Target option indicating the
destination D and a sequence Via Information option, one for S, which destination D and a sequence Via Information option, one for S, which
is the ingress router of the segment, one for A and then for B, which is the ingress router of the Segment, one for A and then for B, which
are an intermediate routers, and one for C, which is the egress are an intermediate routers, and one for C, which is the egress
router. router.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
skipping to change at page 30, line 37 skipping to change at page 32, line 37
Figure 12: P-DAO from Root Figure 12: P-DAO from Root
Upon reception of the P-DAO, C validates that it can reach D, e.g. Upon reception of the P-DAO, C validates that it can reach D, e.g.
using IPv6 Neighbor Discovery, and if so, propagates the P-DAO using IPv6 Neighbor Discovery, and if so, propagates the P-DAO
unchanged to B. unchanged to B.
B checks that it can reach C and of so, installs a route towards D B checks that it can reach C and of so, installs a route towards D
via C. Then it propagates the P-DAO to A. via C. Then it propagates the P-DAO to A.
The process recurses till the P-DAO reaches S, the ingress of the The process recurses till the P-DAO reaches S, the ingress of the
segment, which installs a route to D via A and sends a DAO-ACK to the Segment, which installs a route to D via A and sends a DAO-ACK to the
Root. Root.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
^ P-DAO-ACK from S ^ P-DAO-ACK from S
 End of changes. 109 change blocks. 
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