draft-ietf-roll-dao-projection-13.txt   draft-ietf-roll-dao-projection-14.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: 2 April 2021 M. Gillmore Expires: 5 April 2021 M. Gillmore
Itron Itron
29 September 2020 2 October 2020
Root initiated routing state in RPL Root initiated routing state in RPL
draft-ietf-roll-dao-projection-13 draft-ietf-roll-dao-projection-14
Abstract Abstract
This document updates RFC 6550 to enable a RPL Root to install and This document updates RFC 6550 to enable a RPL Root to install and
maintain Projected Routes within its DODAG, along a selected set of maintain Projected Routes within its DODAG, along a selected set of
nodes that may or may not include self, for a chosen duration. This nodes that may or may not include self, for a chosen duration. This
potentially enables routes that are more optimized or resilient than potentially enables routes that are more optimized or resilient than
those obtained with the classical distributed operation of RPL, those obtained with the classical distributed operation of RPL,
either in terms of the size of a source-route header or in terms of either in terms of the size of a Routing Header or in terms of path
path length, which impacts both the latency and the packet delivery length, which impacts both the latency and the packet delivery ratio.
ratio.
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 2 April 2021. This Internet-Draft will expire on 5 April 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
skipping to change at page 2, line 20 skipping to change at page 2, line 18
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. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Other Terms . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Other Terms . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6
3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 6 3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 6
4. Identifying a Track . . . . . . . . . . . . . . . . . . . . . 8 4. New RPL Control Messages and Options . . . . . . . . . . . . 8
5. New RPL Control Messages and Options . . . . . . . . . . . . 9 4.1. New P-DAO Request Control Message . . . . . . . . . . . . 8
5.1. New P-DAO Request Control Message . . . . . . . . . . . . 9 4.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 9
5.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 10 4.3. Route Projection Options . . . . . . . . . . . . . . . . 10
5.3. Route Projection Options . . . . . . . . . . . . . . . . 12 4.4. Sibling Information Option . . . . . . . . . . . . . . . 12
5.4. Sibling Information Option . . . . . . . . . . . . . . . 14 5. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 14
6. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 16 5.1. Requesting a Track . . . . . . . . . . . . . . . . . . . 15
6.1. Requesting a Track . . . . . . . . . . . . . . . . . . . 17 5.2. Identifying a Track . . . . . . . . . . . . . . . . . . . 16
6.2. Routing over a Track . . . . . . . . . . . . . . . . . . 18 5.3. Forwarding Along a Track . . . . . . . . . . . . . . . . 17
6.3. Non-Storing Mode Projected Route . . . . . . . . . . . . 18 5.4. Non-Storing Mode Projected Route . . . . . . . . . . . . 18
6.4. Storing Mode Projected Route . . . . . . . . . . . . . . 20 5.5. Storing Mode Projected Route . . . . . . . . . . . . . . 19
7. Security Considerations . . . . . . . . . . . . . . . . . . . 22 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 22 7.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 21
8.2. New RPL Control Message Options . . . . . . . . . . . . . 22 7.2. New RPL Control Message Options . . . . . . . . . . . . . 22
8.3. SubRegistry for the Projected DAO Request Flags . . . . . 23 7.3. SubRegistry for the Projected DAO Request Flags . . . . . 22
8.4. SubRegistry for the PDR-ACK Flags . . . . . . . . . . . . 23 7.4. SubRegistry for the PDR-ACK Flags . . . . . . . . . . . . 23
8.5. Subregistry for the PDR-ACK Acceptance Status Values . . 24 7.5. Subregistry for the PDR-ACK Acceptance Status Values . . 23
8.6. Subregistry for the PDR-ACK Rejection Status Values . . . 24 7.6. Subregistry for the PDR-ACK Rejection Status Values . . . 23
8.7. SubRegistry for the Route Projection Options Flags . . . 24 7.7. SubRegistry for the Route Projection Options Flags . . . 24
8.8. SubRegistry for the Sibling Information Option Flags . . 25 7.8. SubRegistry for the Sibling Information Option Flags . . 24
8.9. Error in Projected Route ICMPv6 Code . . . . . . . . . . 25 7.9. Error in Projected Route ICMPv6 Code . . . . . . . . . . 25
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
10. Normative References . . . . . . . . . . . . . . . . . . . . 26 9. Normative References . . . . . . . . . . . . . . . . . . . . 25
11. Informative References . . . . . . . . . . . . . . . . . . . 26 10. Informative References . . . . . . . . . . . . . . . . . . . 26
Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 28 Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 27
A.1. Loose Source Routing . . . . . . . . . . . . . . . . . . 28 A.1. Loose Source Routing . . . . . . . . . . . . . . . . . . 27
A.2. Transversal Routes . . . . . . . . . . . . . . . . . . . 29 A.2. Transversal Routes . . . . . . . . . . . . . . . . . . . 29
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
B.1. Using Storing Mode P-DAO in Non-Storing Mode MOP . . . . 31
B.2. Projecting a Storing Mode transversal route . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
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 5, line 25 skipping to change at page 5, line 25
2.2. Glossary 2.2. Glossary
This document often uses the following acronyms: This document often uses the following acronyms:
CMO: Control Message Option CMO: Control Message Option
DAO: Destination Advertisement Object DAO: Destination Advertisement Object
DAG: Directed Acyclic Graph DAG: Directed Acyclic Graph
DODAG: Destination-Oriented Directed Acyclic Graph; A DAG with only DODAG: Destination-Oriented Directed Acyclic Graph; A DAG with only
one vertex (i.e., node) that has no outgoing edge (i.e., link) one vertex (i.e., node) that has no outgoing edge (i.e., link)
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
NMPR: Non-Storing Mode Projected Route
MOP: RPL Mode of Operation MOP: RPL Mode of Operation
P-DAO: Projected DAO P-DAO: Projected DAO
PDR: P-DAO Request PDR: P-DAO Request
RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf) RAN: RPL-Aware Node (either a RPL Router or a RPL-Aware Leaf)
RAL: RPL-Aware Leaf RAL: RPL-Aware Leaf
RH: Routing Header
RPI: RPL Packet Information RPI: RPL Packet Information
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 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 SMPR: Storing Mode Projected Route
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.
2.3. Other Terms 2.3. Other Terms
Projected Route: A Projected Route is a path segment that is Projected Route: A Projected Route is a path segment that is
computed remotely, and installed and maintained by a RPL Root. computed remotely, and installed and maintained by a RPL Root.
Projected DAO: A DAO message used to install a Projected Route. Projected DAO: A DAO message used to install a Projected Route.
Track: A complex path with redundant Segments to a destination. Track: A complex path with redundant Segments to a destination.
TrackID: A RPL Local InstanceID with the 'D' bit set. The TrackID TrackID: A RPL Local InstanceID with the 'D' bit set. The TrackID
skipping to change at page 6, line 17 skipping to change at page 6, line 17
In this document, readers will encounter terms and concepts that are In this document, readers will encounter terms and concepts that are
discussed in the "Routing Protocol for Low Power and Lossy Networks" discussed in the "Routing Protocol for Low Power and Lossy Networks"
[RPL] and "Terminology in Low power And Lossy Networks" [RFC7102]. [RPL] and "Terminology in Low power And Lossy Networks" [RFC7102].
3. Updating RFC 6550 3. Updating RFC 6550
Section 6 of [RPL] introduces the RPL Control Message Options (CMO), Section 6 of [RPL] introduces the RPL Control Message Options (CMO),
including the RPL Target Option (RTO) and Transit Information Option including the RPL Target Option (RTO) and Transit Information Option
(TIO), which can be placed in RPL messages such as the Destination (TIO), which can be placed in RPL messages such as the Destination
Advertisement Object (DAO). This specification extends the DAO Advertisement Object (DAO). This specification extends the DAO
message with the Projected DAO (P-DAO); a P-DAO message signals a message with the Projected DAO (P-DAO); a P-DAO message signals one
Projected Route using new CMOs presented therein. or more Projected Route(s) using the new CMOs presented therein.
A Projected Route can be an additional route of higher precedence A Projected Route can be an additional route of higher precedence
within the main DODAG, in which case it is installed with the within the main DODAG. In that case, it is installed with a P-DAO
RPLInstanceID and DODAGID of the main DODAG. using the parameters of the main DODAG, typically a global
RPLInstanceID and the DODAGID field elided as shown in Section 6.4.1.
of [RPL].
A Projected Route can also be a Segment within a Track. A stand- A Projected Route can also be a Segment within a Track. A stand-
alone Segment can be used as a Serial (end-to-end) Track. Segments alone Segment can be used as a Serial Track. Segments can also be
can also be combined to form a Complex Track. The Root uses a local combined to form a Complex Track. The Root uses a local RPL Instance
RPL Instance rooted at the Track Egress to establish and maintain the rooted at the Track Egress to signal the Track. The local
Track. The local RPLInstanceID of the Track is called the TrackID, RPLInstanceID of the Track is called the TrackID, more in
more in Section 4. Section 5.2. A P-DAO message for a Track signals the IPv6 Address of
the Track Egress in the DODAGID field of the DAO Base Object, and the
TrackID in the RPLInstanceID field, as shown in Figure 1.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TrackID |K|D| Flags | Reserved | DAOSequence | | TrackID |K|D| Flags | Reserved | DAOSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ IPv6 Address of the Track Egress + + IPv6 Address of the Track Egress +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: Projected DAO Format for a Track Figure 1: Projected DAO Format for a Track
A P-DAO message signals the IPv6 Address of the Track Egress in the
DODAGID field of the DAO Base Object, and the TrackID in the
RPLInstanceID field, as shown in Figure 1.
In RPL Non-Storing Mode, the TIO and RTO are combined in a DAO In RPL Non-Storing Mode, the TIO and RTO are combined in a DAO
message to inform the DODAG Root of all the edges in the DODAG, which message to inform the DODAG Root of all the edges in the DODAG, which
are formed by the directed parent-child relationships. Options may are formed by the directed parent-child relationships. Options may
be factorized; multiple RTOs may be present to signal a collection of be factorized; multiple RTOs may be present to signal a collection of
children that can be reached via the parent(s) indicated in the children that can be reached via the parent(s) indicated in the
TIO(s) that follows the RTOs. TIO(s) that follows the RTOs. This specification generalizes the
case of a parent that can be used to reach a child with that of a
This specification generalizes the case of a parent that can be used whole Track through which both children and siblings of the Track
to reach a child with that of a whole Track through which both Egress are reachable.
children and siblings may be reached.
New CMOs called the Route Projection Options (RPO) are introduced for New CMOs called the Route Projection Options (RPO) are introduced for
use in P-DAO messages as a multihop alternative to the TIO. One RPO use in P-DAO messages as a multihop alternative to the TIO. One RPO
is the Via Information Option (VIO); the VIO installs a state at each is the Via Information Option (VIO); the VIO installs a state at each
hop along a Storing Mode Projected Route. The other is the Source- hop along a Storing Mode Projected Route (SMPR). The other is the
Routed VIO (SRVIO); the SRVIO installs a source-routing state at the Source-Routed VIO (SRVIO); the SRVIO installs a source-routing state
Segment ingress, which uses that state to encapsulate a packet with a at the Segment ingress, which uses that state to encapsulate a packet
Source-Routing Header along a Non-Storing Mode Projected Route. with a Routing Header (RH) along a Non-Storing Mode Projected Route
(NMPR).
Like in a DAO message, the RTOs can be factorized in a P-DAO, but the Like in a DAO message, the RTOs can be factorized in a P-DAO, but the
CMOs cannot. A P-DAO contains one or more RTOs that indicate the RPOs cannot. A P-DAO contains one or more RTOs that indicate the
destinations that can be reached via the Track, and either one SRVIO destinations that can be reached via the Track, and exactly one RPO
or one VIO signal the sequence of hops between the Track Ingress and that signals the sequence of nodes between the Track Ingress and the
the (penultimate) node before the Track Egress. In Non-Storing Mode, Track Egress, both included. In Non-Storing Mode, the Root sends the
the Root sends the P-DAO to the Track Ingress where the source- P-DAO to the Track Ingress where the source-routing state is stored.
routing state is stored. In Storing Mode, the P-DAO is sent to the In Storing Mode, the P-DAO is sent to the Track Egress and forwarded
Track Egress and forwarded along the Segment in the reverse along the Segment in the reverse direction, installing a Storing Mode
direction, installing a Storing Mode state at each hop. state at each hop. In both cases the Track Ingress generates the P-
DAO-ACK when the installation is successful.
This specification adds another CMO called the Sibling Information This specification adds another CMO called the Sibling Information
Option (SIO) that is used by a RPL Aware Node (RAN) to advertise a Option (SIO) that is used by a RPL Aware Node (RAN) to advertise a
selection of its candidate neighbors as siblings to the Root, more in selection of its candidate neighbors as siblings to the Root, more in
Section 5.4. The sibling selection process is out of scope. Section 4.4. The sibling selection process is out of scope.
Two new RPL Control Messages are also introduced, to enable a RAN to Two new RPL Control Messages are also introduced, to enable a RAN to
request the establishment of a Track between self as the Track request the establishment of a Track between self as the Track
Ingress Node and a Track Egress. The RAN makes its request by Ingress Node and a Track Egress. The RAN makes its request by
sending a new P-DAO Request (PDR) Message to the Root. The Root sending a new P-DAO Request (PDR) Message to the Root. The Root
confirms with a new PDR-ACK message back to the requester RAN, see confirms with a new PDR-ACK message back to the requester RAN, see
Section 5.1 for more. A positive PDR-ACK indicates that the Track Section 4.1 for more. A positive PDR-ACK indicates that the Track
was built and that the Roots commits to maintain the Track for a was built and that the Roots commits to maintain the Track for the
negotiated lifetime. negotiated lifetime. In the case of a complex Track, each Segment is
maintained independently and asynchronously by the Root, with its own
In the case of a complex Track, each Segment is maintained lifetime that may be shorter, the same, or longer than that of the
independently and asynchronously by the Root, with its own lifetime Track. The Root may use an asynchronous PDR-ACK with an negative
that may be shorter, the same, or longer than that of the Track. The status to indicate that the Track was terminated before its time.
Root may use an asynchronous PDR-ACK with an negative status to
indicate that the Track was terminated before its time.
4. Identifying a Track
RPL defines the concept of an Instance to signal an individual
routing topology but does not have a concept of an administrative
distance, which exists in certain proprietary implementations to sort
out conflicts between multiple sources of routing information within
one routing topology.
This draft conforms the RPL Instance model as follows:
* The PCE MAY use P-DAO messages to add better routes in the main
(Global) Instance in conformance with the routing objectives in
that Instance. To achieve this, the PCE MAY install a Storing
Mode Projected Route along a path down the main (Non-Storing Mode)
DODAG. This enables a loose source routing and reduces the size
of the Source Routing Header, see Appendix A.1.
When adding a Storing Mode Projected Route to the main RPL
Instance, the Root MUST set the RPLInstanceID field of the DAO
message (see section 6.4.1. of [RPL]) to the RPLInstanceID of the
main DODAG, and set the DODAGID field to the Segment Egress. The
Projected Route provides a longer match to the Egress than the
default route via the Root, so it is preferred. Once the
Projected Route is installed, the intermediate nodes listed in the
VIO between the first (excluded) and the last (included) can be
elided in a Source-Route Header that signals that Segment.
* The Root MAY also use P-DAO messages to install a specific (say,
Traffic Engineered) path as a Serial of a Complex Track, to a
particular endpoint that is the Track Egress. In that case, the
Root MUST use a Local RPL Instance (see section 5 of [RPL]) as
TrackID.
The TrackID MUST be unique for the Global Unique IPv6 Address
(GUA) or Unique-Local Address (ULA) of the Track Egress that
serves as DODAGID for the Track. This way, a Track is uniquely
identified by the tuple (Track Egress Address, TrackID) where the
TrackID is always represented with the 'D' flag set. The Track
Egress Address and the TrackID are signaled in the P-DAO message
as shown in Figure 1.
* In the data packets, the Track Egress Address and the TrackID are
respectively signaled in IPv6 Address of the final destination and
the RPLInstanceID field of the RPL Packet Information (RPI) (see
[USEofRPLinfo]) in the outer chain of IPv6 Headers.
If the outer chain of IPv6 Headers contains a Source-Routing
Header that is not fully consumed, then the final destination is
the last entry in the Source-Routing Header; else it is the
Destination Address in the IPv6 Header. When using the [RFC8138]
compression, it is the last hop of the last SRH-6LoRH of the outer
header in either case.
The 'D' flag in the RPLInstanceID MUST be set to indicate that the
final destination address in the IPv6 header owns the local
RPLInstanceID, more in Section 6.2.
* A packet that is being routed over the RPL Instance associated to
a first Non-Storing Mode Track MAY be placed (encapsulated) in a
second Track to cover one loose hop of the first Track. On the
other hand, a Storing Mode Track must be strict and a packet that
it placed in a Storing Mode Track MUST follow that Track till the
Track Egress.
When a Track Egress extracts a packet from a Track (decapsulates
the packet), the Destination of the inner packet MUST be either
this node or a direct neighbor, otherwise the packet MUST be
dropped. That Destination may be the next Hop in a Non-Storing
Mode Track.
All properties of a Track operations are inherited form the main RPL
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
main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the
RPL configuration option.
5. New RPL Control Messages and Options 4. New RPL Control Messages and Options
5.1. New P-DAO Request Control Message 4.1. 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 by a Node in the main DODAG
that the PCE establishes a new a projected route from self to the to the Root. It is a request to establish or refresh a Track.
Track Egress indicated in the TIO as a full path of a collection of Exactly one RTO MUST be present in a PDR. The RTO signals the Track
Segments in a Track. Exactly one TIO MUST be present, more in Egress, more in Section 5.1.
Section 6.1.
The RPL Control Code for the PDR is 0x09, to be confirmed by IANA. 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 | ReqLifetime | PDRSequence | | TrackID |K|R| Flags | ReqLifetime | PDRSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
skipping to change at page 10, line 23 skipping to change at page 8, line 35
Figure 2: New P-DAO Request Format Figure 2: 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 request a Complex Track for redundancy.
redundant.
Flags: Reserved. The Flags field MUST initialized to zero by the Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver sender and MUST be ignored by the receiver
ReqLifetime: 8-bit unsigned integer. ReqLifetime: 8-bit unsigned integer. The requested lifetime for the
Track expressed in Lifetime Units (obtained from the DODAG
The requested lifetime for the Track expressed in Lifetime Units 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 PDR message that triggered it. It is
The PDRSequence is used to correlate a PDR-ACK message with the incremented at each PDR message and echoed in the PDR-ACK by the
PDR message that triggered it. It is incremented at each PDR Root.
message and echoed in the PDR-ACK by the Root.
5.2. New PDR-ACK Control Message 4.2. 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. The RPL Control Code for the PDR-ACK is 0x0A, to be flag set. The RPL Control Code for the PDR-ACK is 0x0A, to be
confirmed by IANA. Its format is as follows: 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 11, line 24 skipping to change at page 9, line 30
Figure 3: New PDR-ACK Control Message Format Figure 3: New PDR-ACK Control Message Format
TrackID: The RPLInstanceID of the Track that was created. The value TrackID: The RPLInstanceID of the Track that was created. The value
of 0x00 is used to when no Track was created. of 0x00 is used to when no Track was created.
Flags: Reserved. The Flags field MUST initialized to zero by the Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver sender and MUST be ignored by the receiver
Track Lifetime: Indicates that remaining Lifetime for the Track, Track Lifetime: Indicates that remaining Lifetime for the Track,
expressed in Lifetime Units; a value of zero (0x00) indicates that expressed in Lifetime Units; the value of zero (0x00) indicates
the Track was destroyed or not created. 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 substructured as indicated in Figure 4:
The PDR-ACK Status is substructured as indicated in Figure 4:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|E|R| Value | |E|R| Value |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 4: PDR-ACK status Format Figure 4: PDR-ACK status Format
E: 1-bit flag. Set to indicate a rejection. When not set, a E: 1-bit flag. Set to indicate a rejection. When not set, the
value of 0 indicates Success/Unqualified acceptance and other value of 0 indicates Success/Unqualified acceptance and other
values 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 R: 1-bit flag. Reserved, MUST be set to 0 by the sender and
ignored 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 setting of the 'E' flag, see Table 4 and Table 5.
and Table 5.
Reserved: The Reserved field MUST initialized to zero by the sender Reserved: The Reserved field MUST initialized to zero by the sender
and MUST be ignored by the receiver and MUST be ignored by the receiver
5.3. Route Projection Options 4.3. Route Projection Options
The RPOs indicate a series of IPv6 addresses that can be compressed
using the method defined in the "6LoWPAN Routing Header" [RFC8138]
specification using the address of the Root found in the DODAGID
field of DIO messages as Compression Reference.
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
RPO may be placed after a TIO to reflect different Segments
originated at this node. The Track is identified by a TrackID that
is a Local RPLInstanceID to the Track Egress of the Track.
The format of RPOs is as follows: An RPO signals the ordered list of IPv6 Via Addresses that
constitutes the hops of either a Serial Track or a Segment of a more
Complex Track. 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. The format of the 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 | Flags | SegmentID | | Type | Option Length | Flags | SegmentID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Segm. Sequence | Seg. Lifetime | SRH-6LoRH header | |Segm. Sequence | Seg. Lifetime | SRH-6LoRH header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
skipping to change at page 13, line 10 skipping to change at page 10, line 51
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Route Projection Option format (uncompressed form) Figure 5: Route Projection Option format (uncompressed form)
Option Type: 0x0B for VIO, 0x0C for SRVIO (to be confirmed by IANA) Option Type: 0x0B for VIO, 0x0C 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 and the compression. Addresses and the compression.
Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver
SegmentID: 8-bit field that identifies a Segment within a Track or SegmentID: 8-bit field that identifies a Segment within a Track or
the main DODAG as indicated by the TrackID field. A Value of 0 is the main DODAG as indicated by the TrackID field. The value of 0
used to signal a Serial Track, i.e., made of a single segment. is used to signal a Serial Track, 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 refresh or starts at 255.
update a Segment in a Track, it increments the Segment Sequence
individually for that Segment. The Segment information indicated When the Root of the DODAG needs to refresh or update a Segment in
in the RTO deprecates any state for the Segment indicated by the a Track, it increments the Segment Sequence individually for that
SegmentID within the indicated Track and sets up the new Segment.
information. A RTO with a Segment Sequence that is not as fresh
as the current one is ignored. a RTO for a given Track Egress The Segment information indicated in the RPO deprecates any state
with the same (TrackID, SegmentID, Segment Sequence) indicates a for the Segment indicated by the SegmentID within the indicated
retry; it MUST NOT change the Segment and MUST be propagated or Track and sets up the new information.
answered as the first copy.
An RPO with a Segment Sequence that is not as fresh as the current
one is ignored.
An RPO for a given Track Egress with the same (TrackID, SegmentID,
Segment Sequence) indicates a retry; it MUST NOT change the
Segment and MUST be propagated or answered as the first copy.
Segment Lifetime: 8-bit unsigned integer. The length of time in Segment Lifetime: 8-bit unsigned integer. The length of time in
Lifetime Units (obtained from the Configuration option) that the Lifetime Units (obtained from the Configuration option) that the
Segment is usable. The period starts when a new Segment Sequence Segment is usable.
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 Track Egress is referred as a No-Path (for that Track
Egress) in this document.
SRH-6LoRH header: The first 2 bytes of the SRH-6LoRH as shown in The period starts when a new Segment Sequence is seen. The value
Figure 6 of [RFC8138]. A 6LoRH Type of 4 means that the VIA of 255 (0xFF) represents infinity. The value of zero (0x00)
Addresses are provided in full with no compression. indicates a loss of reachability.
Via Address: A Luistof Via Addresses along one Segment, indicated in A P-DAO message that contains a Via Information option with a
the order of the path from the ingress to the egress nodes. Segment Lifetime of zero for a Track Egress is referred as a No-
Path (for that Track Egress) in this document.
SRH-6LoRH header: The first 2 bytes of the (first) SRH-6LoRH as
shown in Figure 6 of [RFC8138]. A 6LoRH Type of 4 means that the
VIA Addresses are provided in full with no compression.
Via Address: An IPv6 addresse along the Segment.
In a VIO, the list is a strict path between direct neighbors, In a VIO, the list is a strict path between direct neighbors,
whereas for an SRVIO, the list may be loose, provided that each whereas for an SRVIO, the list may be loose, provided that each
listed node has a path to the next listed node, e.g., via another listed node has a path to the next listed node, e.g., via another
Track. Track.
In the case of a VIO, or if [RFC8138] is turned off, then the Root In the case of a SMPR, or if [RFC8138] is not used in the data
MUST use only one SRH-6LoRH per RPO, and the compression is the packets, then the Root MUST use only one SRH-6LoRH per RPO, and
same for all the addresses, as shown in Figure 5. the compression is the same for all the addresses, as shown in
Figure 5.
If [RFC8138] is turned on, then the Root SHOULD optimize the size
of the SRVIO; in that case, more than one SRH-6LoRH may be needed
if the compression of the addresses changes inside the Segment and
different SRH-6LoRH Types are used.
An RPO MUST contain at least one Via Address, and a Via Address MUST In case of a NMPR, and if [RFC8138] is in use in the main DODAG,
NOT be present more than once, otherwise the RPO MUST be ignored. then the Root SHOULD optimize the size of the SRVIO; more than one
SRH-6LoRH may be present, e.g., if the compression level changes
inside the Segment and different SRH-6LoRH Types are required.
5.4. Sibling Information Option 4.4. 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. One or more
of SIOs is as follows: SIO(s) may be placed in the DAO messages that are sent to the Root in
Non-Storing Mode.
The format of the SIO 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 | Reserved | | Step of Rank | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
skipping to change at page 14, line 51 skipping to change at page 12, line 52
. Sibling Address . . Sibling Address .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Sibling Information Option Format Figure 6: Sibling Information Option Format
Option Type: 0x0D (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, the size of the option.
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 and
its DODAGID if resent. The Compression refernce is the Root of
the main DODAG.
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.
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 Flags: Reserved. The Flags field MUST initialized to zero by the
sender and MUST be ignored by the receiver 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 industrial 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.
Reserved: The Reserved field MUST initialized to zero by the sender Reserved: The Reserved field MUST initialized to zero by the sender
and MUST be ignored by the receiver and MUST be ignored by the receiver
skipping to change at page 16, line 5 skipping to change at page 14, line 5
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
that case the DAG Metric Container provides additional metrics for that case the DAG Metric Container provides additional metrics for
the hop from the Sibling to this node. the hop from the Sibling to this node.
6. Projected DAO 5. Projected DAO
This draft adds a capability to RPL whereby the Root of a DODAG This draft adds a capability to RPL whereby the Root of a DODAG
projects a Track by sending one or more extended DAO message called projects a Track by sending one or more Projected-DAO (P-DAO)
Projected-DAO (P-DAO) messages to chosen routers in the DODAG, messages to selected routers in the DODAG. The P-DAO signals a
indicating one or more sequence(s) of routers inside the DODAG via collection of Targets in the RPL Target Option(s) (RTO). Those
which the Target(s) indicated in the RPL Target Option(s) (RTO) can Targets can be reached via a sequence of routers indicated in a Route
be reached. Projection Option (RPO). A P-DAO message MUST contain exactly one
RPO, which is either a VIO or an SRVIO, and MUST follow one or more
A P-DAO is sent from a global address of the Root to a global address RTOs. There can be at most one such sequence of RTO(s) and an RPO.
of the recipient, and MUST be confirmed by a DAO-ACK, which is sent
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 MUST be sent from the address of the Root that serves as
one or more SRVIOs following it. There can be at most one such DODAGID for the main DODAG. It MUST be sent to a GUA or a ULA of
sequence of RTOs and then RPOs. either the ingress or the egress of the Segment, more below. If the
'K' Flag is present in the P-DAO, and unless the P-DAO does not reach
it, the ingress of the Segment is the node that acknowledges the
message, using a DAO-ACK that MUST be sent back to the address that
serves as DODAGID for the main DODAG.
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 Segment the RPL specification [RPL]; this is determined using the Segment
Sequence information from the RPO as opposed to the Path Sequence Sequence information from the RPO as opposed to the Path Sequence
from a TIO. Also, a Segment Lifetime of 0 in an RPO indicates that from a TIO. Also, a Segment Lifetime of 0 in an RPO indicates that
the projected route associated to the Segment 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 6.3. It uses an * The Non-Storing Mode is discussed in Section 5.4. A Non-Storing
SRVIO that carries a list of Via Addresses to be used as a source- Mode P-DAO carries an SRVIO with the loose list of Via Addresses
routed Segment to the Track Egress. The recipient of the P-DAO is that forms a source-routed Segment to the Track Egress. The
the ingress router of the source-routed Segment. Upon a Non- recipient of the P-DAO is the ingress router of the source-routed
Storing Mode P-DAO, the ingress router installs a source-routed Segment. The ingress router MUST install a source-routed state to
state to the Track Egress and replies to the Root directly with a the Track Egress and reply to the Root directly using a DAO-ACK
DAO-ACK message. message if requested to.
* The Storing Mode is discussed in Section 6.4. It uses a single * The Storing Mode is discussed in Section 5.5. A Storing Mode
VIO, within which are signaled one Via Address per consecutive P-DAO carries a VIO with the strict list of Via Addresses from the
hop, from the ingress to the egress of the path, including the ingress to the egress of the Segment in the data path order. The
list of all intermediate routers in the data path order. The Via routers listed in the Via Addresses, except the egress, MUST
Addresses indicate the routers in which the routing state to the install a routing state to the Target(s) via the next Via Address
Track Egress have to be installed via the next Via Address in the in the VIO. In normal operations, the P-DAO is propagated along
VIO. In normal operations, the P-DAO is propagated along the the chain of Via Routers from the egress router of the path till
chain of Via Routers from the egress router of the path till the the ingress one, which confirms the installation to the Root with
ingress one, which confirms the installation to the Root with a a DAO-ACK message. Note that the Root may be the ingress and it
DAO-ACK message. Note that the Root may be the ingress and it may may be the egress of the Segment, that it can also be neither but
be the egress of the path, that it can also be neither but it it cannot be both.
cannot be both.
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 7.9). 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 ICMP message SHOULD record at least up to the routing header if
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
this node could not reach. if a 6LoWPAN Routing Header (6LoRH)
[RFC8138] is used to carry the IPv6 routing information in the outter
header then that whole 6LoRH information SHOULD be present in the
ICMP message. The sender and exact operation depend on the Mode and
is described in Section 6.3 and Section 6.4 respectively.
6.1. Requesting a Track The portion of the invoking packet that is sent back in the ICMP
message SHOULD record at least up to the RH if one is present, and
this hop of the RH SHOULD be consumed by this 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) [RFC8138] is used to
carry the IPv6 routing information in the outer header then that
whole 6LoRH information SHOULD be present in the ICMP message.
A Node is free to ask the Root for a new Track with a PDR message, The sender and exact operation depend on the Mode and is described in
for a duration indicated in a Requested Lifetime field. Upon that Section 5.4 and Section 5.5 respectively.
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 5.1. Requesting a Track
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 A Node is free to ask the Root for a new Track at any time. This is
them overtime, to serve the Track as needed, without notifying the done with a PDR message, that indicates in the Requested Lifetime
resquesting Node. If the Track fails and cannot be reestablished, field the duration for which the Track should be established. Upon a
the Root notifies the resquesting Node asynchronously with a PDR-ACK PDR, the Root MAY install the necessary Segments, in which case it
with a Track Lifetime of 0, indicating that the Track has failed, and answers with a PDR-ACK indicating the granted Track Lifetime. All
a PDR-ACK Status indicating the reason of the fault. the Segments MUST be of a same mode, either Storing or Non-Storing.
All the Segments MUST be created with the same TrackID and the same
Track Egress signaled in the P-DAO.
All the Segments MUST be of a same mode, either Storing or Non- The Root is free to design the Track as it wishes, and to change the
Storing. All the Segments MUST be created with the same TrackID and Segments overtime to serve the Track as needed, without notifying the
Track Egress in the P-DAO. resquesting Node. 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.
6.2. Routing over a Track When the Track Lifetime that was 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 extend the lifetime of the Track, else the Track
will time out and the Root will tear down the whole structure.
Sending a packet over a Track implies the addition of a RPI to If the Track fails and cannot be restored, the Root notifies the
indicate the Track, in association with the IPv6 destination. In resquesting Node asynchronously with a PDR-ACK with a Track Lifetime
case of a Non-Storing Mode Projected Route, a Source Routing Header of 0, indicating that the Track has failed, and a PDR-ACK Status
is needed as well. indicating the reason of the fault.
The Destination IPv6 Address of a packet that is placed in a Track 5.2. Identifying a Track
MUST be that of the Track Egress 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 RPL defines the concept of an Instance to signal an individual
Egress is the destination of the packet, there is no need for an routing topology but does not have a concept of an administrative
encapsulation. Else, i.e., if the Track Ingress is forwarding a distance, which exists in certain proprietary implementations to sort
packet into the Track, or if the the final destination is reached via out conflicts between multiple sources of routing information within
is not the Track Egress, but reached over the Track via the Track one routing topology.
Egress, then an IP-in-IP encapsulation is needed.
6.3. Non-Storing Mode Projected Route This draft leverages the RPL Instance model as follows:
* The Root MAY use P-DAO messages to add better routes in the main
(Global) Instance in conformance with the routing objectives in
that Instance. To achieve this, the Root MAY install an SMPR
along a path down the main Non-Storing Mode DODAG. This enables a
loose source routing and reduces the size of the Routing Header,
see Appendix A.1.
When adding an SMPR to the main RPL Instance, the Root MUST set
the RPLInstanceID field of the P-DAO message (see section 6.4.1.
of [RPL]) to the RPLInstanceID of the main DODAG, and MUST NOT use
the DODAGID field. A Projected Route provides a longer match to
the Target Address than the default route via the Root, so it is
preferred.
Once the Projected Route is installed, the intermediate nodes
listed in the VIO after first one (i.e. The ingress) can be
elided from the RH in packets sent along the Segment signaled in
the P-DAO. The resulting loose source routing header indicates
(one of) the Target(s) as the next entry after the ingress.
* The Root MAY also use P-DAO messages to install a specific (say,
Traffic Engineered) path as a Serial or as a Complex Track, to a
particular endpoint that is the Track Egress. In that case, the
Root MUST install a Local RPL Instance (see section 5 of [RPL]).
In a that case, the TrackID MUST be unique for the Global Unique
IPv6 Address (GUA) or Unique-Local Address (ULA) of the Track
Egress that serves as DODAGID for the Track. This way, a Track is
uniquely identified by the tuple (Track Egress Address, TrackID)
where the TrackID is always represented with the 'D' flag set.
The Track Egress Address and the TrackID MUST be signaled in the
P-DAO message as shown in Figure 1.
5.3. Forwarding Along a Track
Sending a Packet within a RPL Local Instance requires the presence of
an RPL Packet Information (RPI) (see [USEofRPLinfo]) in the outer
IPv6 Header chain. The RPI carries a local RPLInstanceID which, in
association with the IPv6 final destination, indicates the RPL
Instance that the packet follows.
This draft leverages the RPL Forwarding model follows:
* The RPI carries a local RPLInstanceID called the TrackID, which,
in association with the IPv6 final destination, indicates the
Track along which the packet is forwarded. The 'D' flag in the
RPLInstanceID MUST be set to indicate that the final destination
address in the IPv6 header owns the local RPLInstanceID, more in
Section 5.3.
In the data packets, the Track Egress Address and the TrackID MUST
be respectively signaled as the IPv6 Address of the final
destination and the RPLInstanceID field of the RPI that MUST be
placed in the outer chain of IPv6 Headers.
In case of a NMPR, the outer chain of IPv6 Headers contains an
IPv6 RH as well. If it is not fully consumed, then the final
destination is the last entry in the RH; else it is the
Destination Address in the IPv6 Header. When using the [RFC8138]
compression, it is the last hop of the last SRH-6LoRH of the outer
header in either case.
* If the Track Ingress is the originator of the packet and the Track
Egress is the destination of the packet, there is no need for an
encapsulation. Else, i.e., if the Track Ingress is forwarding a
packet into the Track, or if the the final destination is reached
over the Track via the Track Egress but is located beyond it, then
an IP-in-IP encapsulation is needed.
A packet that is being routed over the RPL Instance associated to
a first Non-Storing Mode Track MAY be placed (encapsulated) in a
second Track to cover one loose hop of the first Track. On the
other hand, a Storing Mode Track must be strict and a packet that
it placed in a Storing Mode Track MUST follow that Track till the
Track Egress.
When a Track Egress extracts a packet from a Track (decapsulates
the packet), the Destination of the inner packet MUST be either
this node or a direct neighbor, or a Target of another Segment of
the same Track for which this node is ingress, otherwise the
packet MUST be dropped.
All properties of a Track operations are inherited form the main RPL
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
main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the
RPL configuration option.
5.4. Non-Storing Mode Projected Route
As illustrated in Figure 7, a P-DAO that carries an SRVIO enables the As illustrated in Figure 7, a P-DAO that carries an SRVIO enables the
Root to install a source-routed path towards a Track Egress in any Root to install a source-routed path towards a Track Egress in any
particular router; with this path information the router can add a particular router.
source routed header reflecting the Projected Route to any packet for
which the current destination either is the said Track Egress or can
be reached via the Track Egress.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ | P ^ | +-----+ | P ^ ACK
| | DAO | ACK | Loose | Track | DAO |
o o o o router V | | Source o o o o Ingress X V | X
o o o o o o o o o | P-DAO . Route o o o o o o o X o X Source
o o o o o o o o o o | Source . Path o o o o o o o o X o o X Routed
o o o o o o o o o | Route . From o o ° o o o o X o X Segment
o o o o o o o o | Path . Root o o o o o o o o X Track X
o o o o o Track Egress V . To o o o o o Egress
o o o o | Desti-
o o o o | nation o o o o
destination V o o o o
destination
LLN LLN
Figure 7: Projecting a Non-Storing Route Figure 7: Projecting a Non-Storing Route
A route indicated by an SRVIO may be loose, meaning that the node A route indicated by an SRVIO may be loose, meaning that the node
that owns the next listed Via Address is not necessarily a neighbor. that owns the next listed Via Address is not necessarily a neighbor.
Without proper loop avoidance mechanisms, the interaction of loose Without proper loop avoidance mechanisms, the interaction of loose
source routing and other mechanisms may effectively cause loops. In source routing and other mechanisms may effectively cause loops.
order to avoid those loops, if the router that installs a Projected
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
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
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 Track Egress, the router determines that routing happens via the Track Egress, the router
inserts the source routing header in the packet with the destination inserts the source routing header in the packet with the destination
set to the Track Egress. In order to add a source-routing header, set to the Track Egress.
the router encapsulates the packet with an IP-in-IP header and a Non-
Storing Mode source routing header (SRH) [RFC6554]. In the In order to signal the Segment, the router encapsulates the packet
uncompressed form the source of the packet would be self, the with an IP-in-IP header and a Routing Header as follows:
destination would be the first Via Address in the SRVIO, and the SRH
would contain the list of the remaining Via Addresses and then the * In the uncompressed form the source of the packet is this router,
Track Egress. the destination is the first Via Address in the SRVIO, and the RH
is a Source Routing Header (SRH) [RFC6554] that contains the list
of the remaining Via Addresses terminating by the Track Egress.
* The preferred alternate in a network where 6LoWPAN Header
Compression [RFC6282] is used is to leverage "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch"
[RFC8025] to compress the RPL artifacts as indicated in [RFC8138].
In that case, the source routed header is the exact copy of the
(chain of) SRH-6LoRH found in the SRVIO, also terminating by the
Track Egress. The RPI-6LoRH is appended next, followed by an IP-
in-IP 6LoRH Header that indicates the Ingress Router in the
Encapsulator Address field, see as a similar case Figure 20 of
[TURN-ON_RFC8138].
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 another Track to the loose
loose next hop; in the latter case, another encapsulation takes place next hop for which this node is Ingress; in the latter case, another
and the process possibly recurses; otherwise the packet is dropped. encapsulation takes place and the process possibly recurses;
otherwise the packet is dropped.
In practice, the router will normally use the "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch" [RFC8025]
to compress the RPL artifacts as indicated in [RFC8138]. In that
case, the router indicates self as encapsulator in an IP-in-IP 6LoRH
Header, and places the list of Via Addresses in the order of the
SRVIO and then the Track Egress in the SRH 6LoRH Header.
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.
6.4. Storing Mode Projected Route 5.5. Storing Mode Projected Route
As illustrated in Figure 8, the Storing Mode route projection is used As illustrated in Figure 8, a P-DAO that carries a VIO enables the
by the Root to install a routing state in the routers along a Segment Root to install a stateful route towards a collection of Targets
between an Ingress and an Egress router this enables the routers to along a Segment between a Track Ingress and a Track Egress.
forward along that Segment any packet for which the next loose hop is
the Egress node, for instance a loose source routed packet for which
the next loose hop is the Egress node, or a packet for which the
router has a routing state to the final destination via the Egress
node.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ | ^ | +-----+ | ^ |
| | DAO | ACK | | | DAO | ACK |
o o o o | | | o o o o | | |
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 8: Projecting a route Figure 8: 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 the Root sends a unicast P-DAO message to the Track Egress router of
P-DAO message to the egress router of the routing Segment that must the routing Segment that is being installed. The P-DAO message
be installed. The P-DAO message contains the ordered list of hops contains a VIO with the direct sequence of Via Addresses. The VIO
along the Segment as a direct sequence of Via Information options follows one or more RTOs indicating the Targets to which the Track
that are preceded by one or more RPL Target options to which they leads. The VIO contains a Segment Lifetime for which the state is to
relate. Each Via Information option contains a Segment Lifetime for 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 last Via In that P-DAO, the destination IP address matches the last Via
Address in the VIO. This is how the egress recognizes its role. In Address in the VIO. This is how the egress recognizes its role. In
a similar fashion, the ingress node recognizes its role as it matches a similar fashion, the ingress node recognizes its role as it matches
first Via Address in the VIO. first Via Address in the 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. If one of the
the Target, or may have some existing information to reach the Targets is not known, the node MUST answer to the Root with a
Target(s), such as a connected route or an already installed negative DAO-ACK listing the Target(s) that could not be located
Projected Route. If one of the Targets cannot be located, the node (suggested status 10 to be confirmed by IANA).
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
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 Address the precedes the
precedes the one that contain the address of the propagating node, one that contain the address of the propagating node, which is used
which is used as source of the packet. as source of the message.
Upon receiving a propagated DAO, an intermediate router as well as Upon receiving a propagated DAO, all except the Egress Router MUST
the ingress router install a route towards the DAO Target(s) via its install a route towards the DAO Target(s) via their successor in the
successor in the P-DAO; the router locates its address in the VIO, VIO. The router MAY install additional routes towards the VIA
and uses as next hop the address found in the previous Via Address Addresses that are the VIO after the next one, if any, but in case of
field in the VIO. The router MAY install additional routes towards a conflict or a lack of resource, the route(s) to the Target(s) have
the VIA Addresses that are the VIO after the next one, if any, but in precedence.
case of a conflict or a lack of resource, the route(s) to the
Target(s) have precedence.
The process recurses till the P-DAO is propagated to ingress router If a router cannot reach its predecessor in the VIO, the router MUST
of the Segment, which answers with a DAO-ACK to the Root. answer to the Root with a negative DAO-ACK indicating the successor
that is unreachable (suggested status 11 to be confirmed by IANA).
Also, the path indicated in a P-DAO may be loose, in which case the The process continues till the P-DAO is propagated to ingress router
reachability to the next hop has to be asserted. Each router along of the Segment, which answers with a DAO-ACK to the Root.
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
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
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
router in the P-DAO, the router MUST answer to the Root with a
negative DAO-ACK indicating the successor that is unreachable
(suggested status 11 to be confirmed by IANA).
A Segment Lifetime of 0 in a Via Information option is used to clean A Segment Lifetime of 0 in a Via Information option is used to clean
up the state. The P-DAO is forwarded as described above, but the DAO up the state. The P-DAO is forwarded as described above, but the DAO
is 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 an SMPR, the node that fails to
the node that fails to forward SHOULD send an ICMP error with a code forward SHOULD send an ICMP error with a code "Error in Projected
"Error in Projected Route" to the Root. Failure to do so may result Route" to the Root. Failure to do so may result in packet loss and
in packet loss and wasted resources along the Projected Route that is wasted resources along the Projected Route that is broken.
broken.
7. Security Considerations 6. Security Considerations
This draft uses messages that are already present in RPL [RPL] with This draft uses messages that are already present in RPL [RPL] with
optional secured versions. The same secured versions may be used optional secured versions. The same secured versions may be used
with this draft, and whatever security is deployed for a given with this draft, and whatever security is deployed for a given
network also applies to the flows in this draft. network also applies to the flows in this draft.
TODO: should probably consider how P-DAO messages could be abused by TODO: should probably consider how P-DAO messages could be abused by
a) rogue nodes b) via replay of messages c) if use of P-DAO messages a) rogue nodes b) via replay of messages c) if use of P-DAO messages
could in fact deal with any threats? could in fact deal with any threats?
8. IANA Considerations 7. IANA Considerations
8.1. New RPL Control Codes 7.1. New RPL Control Codes
This document extends the IANA Subregistry created by RFC 6550 for This document extends the IANA Subregistry created by RFC 6550 for
RPL Control Codes as indicated in Table 1: RPL Control Codes as indicated in Table 1:
+======+=============================+===============+ +======+=============================+===============+
| Code | Description | Reference | | Code | Description | Reference |
+======+=============================+===============+ +======+=============================+===============+
| 0x09 | Projected DAO Request (PDR) | This document | | 0x09 | Projected DAO Request (PDR) | This document |
+------+-----------------------------+---------------+ +------+-----------------------------+---------------+
| 0x0A | PDR-ACK | This document | | 0x0A | PDR-ACK | This document |
+------+-----------------------------+---------------+ +------+-----------------------------+---------------+
Table 1: New RPL Control Codes Table 1: New RPL Control Codes
8.2. New RPL Control Message Options 7.2. New RPL Control Message Options
This document extends the IANA Subregistry created by RFC 6550 for This document extends the IANA Subregistry created by RFC 6550 for
RPL Control Message Options as indicated in Table 2: RPL Control Message Options as indicated in Table 2:
+=======+======================================+===============+ +=======+======================================+===============+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+======================================+===============+ +=======+======================================+===============+
| 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. SubRegistry for the Projected DAO Request Flags 7.3. 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 23, line 43 skipping to change at page 23, line 16
| 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. SubRegistry for the PDR-ACK Flags 7.4. 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. Subregistry for the PDR-ACK Acceptance Status Values 7.5. Subregistry for the PDR-ACK Acceptance Status Values
IANA is requested to create a Subregistry for the PDR-ACK Acceptance IANA is requested to create a Subregistry for the PDR-ACK 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. Subregistry for the PDR-ACK Rejection Status Values 7.6. Subregistry for the PDR-ACK Rejection Status Values
IANA is requested to create a Subregistry for the PDR-ACK Rejection IANA is requested to create a Subregistry for the PDR-ACK 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. SubRegistry for the Route Projection Options Flags 7.7. SubRegistry for the Route Projection Options Flags
IANA is requested to create a 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. SubRegistry for the Sibling Information Option Flags 7.8. 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 25, line 34 skipping to change at page 25, line 13
allocation is as indicated in Table 6: allocation is as indicated in Table 6:
+============+===================================+===============+ +============+===================================+===============+
| Bit number | Capability description | Reference | | Bit number | Capability description | Reference |
+============+===================================+===============+ +============+===================================+===============+
| 0 | Connectivity is bidirectional (B) | This document | | 0 | Connectivity is bidirectional (B) | This document |
+------------+-----------------------------------+---------------+ +------------+-----------------------------------+---------------+
Table 6: Initial SIO Flags Table 6: Initial SIO Flags
8.9. Error in Projected Route ICMPv6 Code 7.9. Error in Projected Route ICMPv6 Code
In some cases RPL will return an ICMPv6 error message when a message In some cases RPL will return an ICMPv6 error message when a message
cannot be forwarded along a Projected Route. This ICMPv6 error cannot be forwarded along a Projected Route. This ICMPv6 error
message is "Error in Projected Route". message is "Error in Projected Route".
IANA has defined an ICMPv6 "Code" Fields Registry for ICMPv6 Message IANA has defined an ICMPv6 "Code" Fields Registry for ICMPv6 Message
Types. ICMPv6 Message Type 1 describes "Destination Unreachable" Types. ICMPv6 Message Type 1 describes "Destination Unreachable"
codes. This specification requires that a new code is allocated from codes. This specification requires that a new code is allocated from
the ICMPv6 Code Fields Registry for ICMPv6 Message Type 1, for "Error the ICMPv6 Code Fields Registry for ICMPv6 Message Type 1, for "Error
in Projected Route", with a suggested code value of 8, to be in Projected Route", with a suggested code value of 8, to be
confirmed by IANA. confirmed by IANA.
9. Acknowledgments 8. Acknowledgments
The authors wish to acknowledge JP Vasseur, Remy Liubing, James The authors wish to acknowledge JP Vasseur, Remy Liubing, James
Pylakutty and Patrick Wetterwald for their contributions to the ideas Pylakutty and Patrick Wetterwald for their contributions to the ideas
developed here. developed here.
10. Normative References 9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89, Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006, RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>. <https://www.rfc-editor.org/info/rfc4443>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>.
[RPL] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RPL] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554,
skipping to change at page 26, line 40 skipping to change at page 26, line 23
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
11. Informative References 10. Informative References
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <https://www.rfc-editor.org/info/rfc7102>. 2014, <https://www.rfc-editor.org/info/rfc7102>.
[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>.
skipping to change at page 27, line 21 skipping to change at page 27, line 6
[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, 6 July 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, "A RPL DODAG Configuration Option
8138", Work in Progress, Internet-Draft, draft-thubert- for the 6LoWPAN Routing Header", Work in Progress,
roll-turnon-rfc8138-03, 8 July 2019, Internet-Draft, draft-ietf-roll-turnon-rfc8138-17, 30
<https://tools.ietf.org/html/draft-thubert-roll-turnon- September 2020, <https://tools.ietf.org/html/draft-ietf-
rfc8138-03>. roll-turnon-rfc8138-17>.
[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] [USEofRPLinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPI Robles, I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes and IPv6-in- Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", Work in IPv6 encapsulation in the RPL Data Plane", Work in
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-40, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-41,
25 June 2020, <https://tools.ietf.org/html/draft-ietf- 21 September 2020, <https://tools.ietf.org/html/draft-
roll-useofrplinfo-40>. ietf-roll-useofrplinfo-41>.
[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 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 9. uses the Non-Storing Mode of Operation as represented in Figure 9.
skipping to change at page 29, line 19 skipping to change at page 29, 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 a Storing Mode state in
state in intermediate routers, which enables to limit the excursion intermediate routers, which enables to limit the excursion of the
of the source route headers in deep networks. Once a P-DAO exchange source route headers in deep networks. Once a P-DAO exchange has
has taken place for a given Target, if the Root operates in non taken place for a given Target, if the Root operates in non Storing
Storing Mode, then it may elide the sequence of routers that is Mode, then it may elide the sequence of routers that is installed in
installed in the network from its source route headers to destination the network from its source route headers to destination that are
that are reachable via that Target, and the source route headers reachable via that Target, and the source route headers effectively
effectively become loose. become loose.
A.2. Transversal Routes 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 10: illustrated in Figure 10:
skipping to change at page 30, line 7 skipping to change at page 29, line 49
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 * 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 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 same DODAG, the Root must encapsulate the packet to place an RH
Routing Header that has the strict source route information down that has the strict source route information down the DODAG to the
the DODAG to the destination. This will be the case even if the destination. This will be the case even if the destination is
destination is relatively close to the source and the Root is relatively close to the source and the Root is relatively far off.
relatively far off.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
X X
^ v o o ^ v o o
skipping to change at page 31, line 32 skipping to change at page 31, line 14
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
B.1. Using Storing Mode P-DAO in Non-Storing Mode MOP
In Non-Storing Mode, the DAG Root maintains the knowledge of the
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
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
Instance in the diagram shown in Figure 12, if the source is node 41
and the destination is node 52, then the common parent is node 22.
------+---------
| Internet
|
+-----+
| | Border Router
| | (RPL Root)
+-----+
| \ \____
/ \ \
o 11 o 12 o 13
/ | / \
o 22 o 23 o 24 o 25
/ \ | \ \
o 31 o 32 o o o 35
/ / | \ | \
o 41 o 42 o o o 45 o 46
| | | | \ |
o 51 o 52 o 53 o o 55 o 56
LLN
Figure 12: Example DODAG forming a logical tree topology
With this draft, the Root can install a Storing Mode routing states
along a Segment that is either from itself to the destination, or
from one or more common parents for a particular source/destination
pair towards that destination (in this particular example, this would
be the Segment made of nodes 22, 32, 42).
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
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
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
may then send a DAO to node 35 indicating Targets 55 and 56 a Via
Segment (13, 24, 35) to fully optimize that path.
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
indicating Target 56 and a Via Segment (13, 24, 35, 46), indicating
the same DAO Sequence.
B.2. Projecting a Storing Mode transversal route
In this example, say that a PCE determines that a path must be
installed between node I and node D via routers A, B and E, in order
to serve the needs of a particular application.
The Root sends a P-DAO to node E, with an RTO indicating the
destination D, a TIO optionally indicating the Track Egress in the
Parent Address field, and a sequence of Via Information options
indicating the hops, one for S, which is the ingress router of the
Segment, one for A, and then one for B, which are respectively the
intermediate and penultimate routers.
------+---------
| Internet
|
+-----+
| | Border Router
| | (RPL Root)
+-----+
| P-DAO message to C
o | o o
o o o | o o o o o
o o o | o o o o o o
o o V o o o o o o
S A B E D o o o
o o o o
LLN
Figure 13: P-DAO from Root
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
unchanged to B.
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.
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
Root.
------+---------
| Internet
|
+-----+
| | Border Router
| | (RPL Root)
+-----+
^ P-DAO-ACK from S
/ 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
o o o o
LLN
Figure 14: P-DAO-ACK to Root
As a result, a transversal route is installed that does not need to
follow the DODAG structure.
------+---------
| Internet
|
+-----+
| | Border Router
| | (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
S>>A>>>B>>C>>>D o o o
o o o o
LLN
Figure 15: Projected Transversal Route
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
06254 Mougins - Sophia Antipolis 06254 Mougins - Sophia Antipolis
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Rahul Arvind Jadhav Rahul Arvind Jadhav
Huawei Tech Huawei Tech
Kundalahalli Village, Whitefield, Kundalahalli Village, Whitefield,
Bangalore 560037 Bangalore 560037
Karnataka Karnataka
India India
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