< draft-ietf-roll-dao-projection-14.txt   draft-ietf-roll-dao-projection-15.txt >
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550 (if approved) R.A. Jadhav Intended status: Standards Track R.A. Jadhav
Intended status: Standards Track Huawei Tech Expires: 31 May 2021 Huawei Tech
Expires: 5 April 2021 M. Gillmore M. Gillmore
Itron Itron
2 October 2020 27 November 2020
Root initiated routing state in RPL Root initiated routing state in RPL
draft-ietf-roll-dao-projection-14 draft-ietf-roll-dao-projection-15
Abstract Abstract
This document updates RFC 6550 to enable a RPL Root to install and This document extends RFC 6550 and RFC 6553 to enable a RPL Root to
maintain Projected Routes within its DODAG, along a selected set of install and maintain Projected Routes within its DODAG, along a
nodes that may or may not include self, for a chosen duration. This selected set of nodes that may or may not include self, for a chosen
potentially enables routes that are more optimized or resilient than duration. This potentially enables routes that are more optimized or
those obtained with the classical distributed operation of RPL, resilient than those obtained with the classical distributed
either in terms of the size of a Routing Header or in terms of path operation of RPL, either in terms of the size of a Routing Header or
length, which impacts both the latency and the packet delivery ratio. in terms of path length, which impacts both the latency and the
packet delivery 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
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This Internet-Draft will expire on 5 April 2021. This Internet-Draft will expire on 31 May 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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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 . . . . . . . . . . . . . . . . . . . . . . . 6
2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6
3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 6 3. Extending RFC 6550 . . . . . . . . . . . . . . . . . . . . . 6
4. New RPL Control Messages and Options . . . . . . . . . . . . 8 3.1. Projected DAO . . . . . . . . . . . . . . . . . . . . . . 6
4.1. New P-DAO Request Control Message . . . . . . . . . . . . 8 3.2. Sibling Information Option . . . . . . . . . . . . . . . 8
4.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 9 3.3. P-DAO Request . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Route Projection Options . . . . . . . . . . . . . . . . 10 3.4. Extending the RPI . . . . . . . . . . . . . . . . . . . . 8
4.4. Sibling Information Option . . . . . . . . . . . . . . . 12 4. Extending RFC 6553 . . . . . . . . . . . . . . . . . . . . . 8
5. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 14 5. Extending RFC 8138 . . . . . . . . . . . . . . . . . . . . . 9
5.1. Requesting a Track . . . . . . . . . . . . . . . . . . . 15 6. New RPL Control Messages and Options . . . . . . . . . . . . 10
5.2. Identifying a Track . . . . . . . . . . . . . . . . . . . 16 6.1. New P-DAO Request Control Message . . . . . . . . . . . . 10
5.3. Forwarding Along a Track . . . . . . . . . . . . . . . . 17 6.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 11
5.4. Non-Storing Mode Projected Route . . . . . . . . . . . . 18 6.3. Via Information Options . . . . . . . . . . . . . . . . . 12
5.5. Storing Mode Projected Route . . . . . . . . . . . . . . 19 6.4. Sibling Information Option . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 7. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 7.1. Requesting a Track . . . . . . . . . . . . . . . . . . . 18
7.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 21 7.2. Identifying a Track . . . . . . . . . . . . . . . . . . . 18
7.2. New RPL Control Message Options . . . . . . . . . . . . . 22 7.3. Installing a Track . . . . . . . . . . . . . . . . . . . 19
7.3. SubRegistry for the Projected DAO Request Flags . . . . . 22 7.4. Forwarding Along a Track . . . . . . . . . . . . . . . . 20
7.4. SubRegistry for the PDR-ACK Flags . . . . . . . . . . . . 23 7.5. Non-Storing Mode Projected Route . . . . . . . . . . . . 21
7.5. Subregistry for the PDR-ACK Acceptance Status Values . . 23 7.6. Storing Mode Projected Route . . . . . . . . . . . . . . 23
7.6. Subregistry for the PDR-ACK Rejection Status Values . . . 23 8. Security Considerations . . . . . . . . . . . . . . . . . . . 25
7.7. SubRegistry for the Route Projection Options Flags . . . 24 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
7.8. SubRegistry for the Sibling Information Option Flags . . 24 9.1. New Elective 6LoWPAN Routing Header Type . . . . . . . . 25
7.9. Error in Projected Route ICMPv6 Code . . . . . . . . . . 25 9.2. New Critical 6LoWPAN Routing Header Type . . . . . . . . 25
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 9.3. New Subregistry For The RPL Option Flags . . . . . . . . 26
9. Normative References . . . . . . . . . . . . . . . . . . . . 25 9.4. New RPL Control Codes . . . . . . . . . . . . . . . . . . 26
10. Informative References . . . . . . . . . . . . . . . . . . . 26 9.5. New RPL Control Message Options . . . . . . . . . . . . . 27
Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 27 9.6. SubRegistry for the Projected DAO Request Flags . . . . . 27
A.1. Loose Source Routing . . . . . . . . . . . . . . . . . . 27 9.7. SubRegistry for the PDR-ACK Flags . . . . . . . . . . . . 28
A.2. Transversal Routes . . . . . . . . . . . . . . . . . . . 29 9.8. Subregistry for the PDR-ACK Acceptance Status Values . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 9.9. Subregistry for the PDR-ACK Rejection Status Values . . . 28
9.10. SubRegistry for the Via Information Options Flags . . . . 29
9.11. SubRegistry for the Sibling Information Option Flags . . 29
9.12. Error in Projected Route ICMPv6 Code . . . . . . . . . . 30
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
11. Normative References . . . . . . . . . . . . . . . . . . . . 30
12. Informative References . . . . . . . . . . . . . . . . . . . 31
Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 32
A.1. Loose Source Routing . . . . . . . . . . . . . . . . . . 32
A.2. Transversal Routes . . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
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 4, line 13 skipping to change at page 4, line 19
Traffic Engineering purposes, between nodes of the DODAG. Traffic Engineering purposes, between nodes of the DODAG.
A Projected Route may be installed in either Storing and Non-Storing A Projected Route may be installed in either Storing and Non-Storing
Mode, potentially resulting in hybrid situations where the Mode of Mode, potentially resulting in hybrid situations where the Mode of
the Projected Route is different from that of the main RPL Instance. the Projected Route is different from that of the main RPL Instance.
A Projected Route may be a stand-alone end-to-end path or a Segment A Projected Route may be a stand-alone end-to-end path or a Segment
in a more complex forwarding graph called a Track. in a more complex forwarding graph called a Track.
The concept of a Track was introduced in the 6TiSCH architecture, as The concept of a Track was introduced in the 6TiSCH architecture, as
a potentially complex path with redundant forwarding solutions along a potentially complex path with redundant forwarding solutions along
the way. A node at the ingress of more than one Segment in a Track the way. With this specification, a Track is a DODAG formed by a RPL
may use any combination of those Segments to forward a packet towards local Instance that is rooted at the Track Ingress. If there is a
the Track Egress. single Track Egress, then the Track is reversible to form another
DODAG by reversing the direction of each edge. A node at the ingress
of more than one Segment in a Track may use one or more of these
Segments to forward a packet inside the Track.
The "Reliable and Available Wireless (RAW) Architecture/Framework" The "Reliable and Available Wireless (RAW) Architecture/Framework"
[RAW-ARCHI] defines the Path Selection Engine (PSE) that adapts the [RAW-ARCHI] defines the Path Selection Engine (PSE) that adapts the
use of the path redundancy within a Track to defeat the diverse use of the path redundancy within a Track to defeat the diverse
causes of packet loss. causes of packet loss.
The PSE is a dataplane extension of the PCE; it controls the The PSE is a dataplane extension of the PCE; it controls the
forwarding operation of the packets within a Track, using Packet ARQ, forwarding operation of the packets within a Track, using Packet ARQ,
Replication, Elimination, and Overhearing (PAREO) functions over the Replication, Elimination, and Overhearing (PAREO) functions over the
Track segments, to provide a dynamic balance between the reliability Track segments, to provide a dynamic balance between the reliability
skipping to change at page 5, line 33 skipping to change at page 5, line 43
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 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 RH: Routing Header
RPI: RPL Packet Information RPI: RPL Packet Information
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 SR-VIO: A Source-Routed Via Information Option, used in Non-Storing
Mode P-DAO messages. Mode P-DAO messages.
SMPR: Storing Mode Projected Route SMPR: Storing Mode Projected Route
TIO: RPL Transit Information Option TIO: RPL Transit Information Option
VIO: A Via Information Option, used in Storing Mode P-DAO messages. SF-VIO: A Via Information Option, used in Storing Mode P-DAO
messages.
VIO: A Via Information Option; it can be a SF-VIO or an SR-VIO.
2.3. Other Terms 2.3. Other Terms
Projected Route: A Projected Route is a path segment that is Projected Route: A RPL Projected Route is a RPL route that is
computed remotely, and installed and maintained by a RPL Root. computed remotely by a PCE, and installed and maintained by a RPL
Root on behalf of the PCE.
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 DODAG that provides a complex path from or to a Root that
TrackID: A RPL Local InstanceID with the 'D' bit set. The TrackID is the destination of the DODAG. The Root is the Track Ingress,
is associated with a IPv6 Address to the Track Egress Node. and the forward direction for packets is down the DODAG, from the
Track Ingress to one of the possibly multiple Track Egress Nodes.
TrackID: A RPL Local InstanceID with the 'D' bit set to 0. The
TrackID is associated with the IPv6 Address of the Track Ingress
that is used to signal the DODAG Root.
2.4. References 2.4. References
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. Extending RFC 6550
3.1. Projected DAO
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 one message with the Projected DAO (P-DAO); a P-DAO message signals a
or more Projected Route(s) using the new CMOs presented therein. Projected Route to one or more Targets using the new CMOs presented
therein. This specification enables to combine one or more Projected
A Projected Route can be an additional route of higher precedence Routes into a DODAG called a Track, that is traversed to reach the
within the main DODAG. In that case, it is installed with a P-DAO Targets.
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- The Track is assimilated with the DODAG formed for a Local RPL
alone Segment can be used as a Serial Track. Segments can also be Instance. The local RPLInstanceID of the Track is called the
combined to form a Complex Track. The Root uses a local RPL Instance TrackID, more in Section 7.2. A P-DAO message for a Track signals
rooted at the Track Egress to signal the Track. The local the TrackID in the RPLInstanceID field. The Track Ingress is
RPLInstanceID of the Track is called the TrackID, more in signaled in the DODAGID field of the Projected DAO Base Object; that
Section 5.2. A P-DAO message for a Track signals the IPv6 Address of field is elided in the case of the main RPL Instance. The Track
the Track Egress in the DODAGID field of the DAO Base Object, and the Ingress is the Root of the Track, as shown in Figure 1. .
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 Ingress +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: Projected DAO Format for a Track Figure 1: Projected DAO Format for a Track
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. This specification generalizes the 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 case of a parent that can be used to reach a child with that of a
whole Track through which both children and siblings of the Track whole Track through which both children and siblings of the Track
Egress are reachable. Egress are reachable.
New CMOs called the Route Projection Options (RPO) are introduced for New CMOs called the Via Information Options (VIO) 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 VIO
is the Via Information Option (VIO); the VIO installs a state at each is the Stateful Via Information Option (SF-VIO); the SF-VIO installs
hop along a Storing Mode Projected Route (SMPR). The other is the Storing Mode Projected Route (SMPR) along a strict segment. The
Source-Routed VIO (SRVIO); the SRVIO installs a source-routing state other is the Source-Routed SF-VIO (SR-VIO); the SR-VIO installs a
at the Segment ingress, which uses that state to encapsulate a packet Non-Storing Mode Projected Route (NMPR) at the Track Ingress, which
with a Routing Header (RH) along a Non-Storing Mode Projected Route uses that state to encapsulate a packet with a Routing Header (RH) to
(NMPR). the Track Egress.
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
RPOs cannot. A P-DAO contains one or more RTOs that indicate the Via Options cannot. A P-DAO contains one or more RTOs that indicate
destinations that can be reached via the Track, and exactly one RPO the destinations that can be reached via the Track, and exactly one
that signals the sequence of nodes between the Track Ingress and the Via Option that signals a sequence of nodes. 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 to the Track Egress at
state at each hop. In both cases the Track Ingress generates the P- each hop. In both cases the Track Ingress is the owner of the Track,
DAO-ACK when the installation is successful. and it generates the P-DAO-ACK when the installation is successful.
3.2. Sibling Information Option
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 4.4. The sibling selection process is out of scope. Section 6.4. The sibling selection process is out of scope.
3.3. P-DAO Request
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 4.1 for more. A positive PDR-ACK indicates that the Track Section 6.1 for more. A positive PDR-ACK indicates that the Track
was built and that the Roots commits to maintain the Track for the was built and that the Roots commits to maintain the Track for the
negotiated lifetime. In the case of a complex Track, each Segment is negotiated lifetime. In the case of a complex Track, each Segment is
maintained independently and asynchronously by the Root, with its own maintained independently and asynchronously by the Root, with its own
lifetime that may be shorter, the same, or longer than that of the lifetime that may be shorter, the same, or longer than that of the
Track. The Root may use an asynchronous PDR-ACK with an negative Track. The Root may use an asynchronous PDR-ACK with an negative
status to indicate that the Track was terminated before its time. status to indicate that the Track was terminated before its time.
4. New RPL Control Messages and Options 3.4. Extending the RPI
4.1. New P-DAO Request Control Message Sending a Packet within a RPL Local Instance requires the presence of
the abstract RPL Packet Information (RPI) described in section 11.2.
of [RPL] in the outer IPv6 Header chain (see [USEofRPLinfo]). The
RPI carries a local RPLInstanceID which, in association with either
the source or the destination address in the IPv6 Header, indicates
the RPL Instance that the packet follows.
This specification extends [RPL] to create a new flag that signals
that a packet is forwarded along a projected route.
Projected-Route 'P': 1-bit flag. It is set to 1 if this packet is
sent over a projected route and set to 0 otherwise.
4. Extending RFC 6553
"The RPL Option for Carrying RPL Information in Data-Plane Datagrams"
[RFC6553]describes the RPL Option for use among RPL routers to
include the abstract RPL Packet Information (RPI) described in
section 11.2. of [RPL] in data packets.
The RPL Option is commonly referred to as the RPI though the RPI is
really the abstract information that is transported in the RPL
Option. [USEofRPLinfo] updated the Option Type from 0x63 to 0x23.
This specification modifies the RPL Option to encode the 'P' flag as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O|R|F|P|0|0|0|0| RPLInstanceID | SenderRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (sub-TLVs) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Extended RPL Option Format
Option Type: 0x23 or 0x63, see [USEofRPLinfo]
Opt Data Len: See [RFC6553]
'O', 'R' and 'F' flags: See [RFC6553]. Those flags MUST be set to 0
by the sender and ignored by the receiver if the 'P' flag is set.
Projected-Route 'P': 1-bit flag as defined in Section 3.4.
RPLInstanceID: See [RFC6553]. Indicates the TrackId if the 'P' flag
is set.
SenderRank: See [RFC6553]. This field MUST be set to 0 by the
sender and ignored by the receiver if the 'P'flag is set.
5. Extending RFC 8138
Section 6.3 of [RFC8138] presents the formats of the 6LoWPAN Routing
Header of type 5 (RPI-6LoRH) that compresses the RPI for normal RPL
operation. The format of the RPI-6LoRH is not suited for Projected
routes since the O,R,F flags are not used and the Rank is unknown and
ignored.
This specification introduces a new 6LoRH, the P-RPI-6LoRH, with a
type of 7. The P-RPI-6LoRH header is usually a a Critical 6LoWPAN
Routing Header, but it can be elective as well if an SRH-6LoRH is
present and controls the routing decision.
The P-RPI-6LoRH is designed to compress the RPI along RPL Projected
Routes. It sformat is as follows:
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|E| Length | 6LoRH Type 7 | RPLInstanceID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: P-RPI-6LoRH Format
Elective 'E': See [RFC8138]. The 'E' flag is set to 1 to indicate
an Elective 6LoRH, meaning that it can be ignored when forwarding.
6. New RPL Control Messages and Options
6.1. New P-DAO Request Control Message
The P-DAO Request (PDR) message is sent by a Node in the main DODAG The P-DAO Request (PDR) message is sent by a Node in the main DODAG
to the Root. It is a request to establish or refresh a Track. to the Root. It is a request to establish or refresh a Track.
Exactly one RTO MUST be present in a PDR. The RTO signals the Track Exactly one RTO MUST be present in a PDR. The RTO signals the Track
Egress, more in Section 5.1. Egress, more in Section 7.1.
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)...
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 2: New P-DAO Request Format Figure 4: 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 request a Complex Track for redundancy. R: The 'R' flag is set to request a Complex Track for redundancy.
skipping to change at page 9, line 5 skipping to change at page 11, line 16
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]. The PDRSequence is used to correlate a 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 PDR-ACK message with the PDR message that triggered it. It is
incremented at each PDR message and echoed in the PDR-ACK by the incremented at each PDR message and echoed in the PDR-ACK by the
Root. Root.
4.2. New PDR-ACK Control Message 6.2. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PDR-ACK Status| Reserved | | PDR-ACK Status| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
Figure 3: New PDR-ACK Control Message Format Figure 5: 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; the value of zero (0x00) indicates expressed in Lifetime Units; the value of zero (0x00) indicates
that 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. The PDR-ACK PDR-ACK Status: 8-bit field indicating the completion. The PDR-ACK
Status is substructured as indicated in Figure 4: Status is substructured as indicated in Figure 6:
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 6: PDR-ACK status Format
E: 1-bit flag. Set to indicate a rejection. When not set, the 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, see Table 4 and Table 5. setting of the 'E' flag, see Table 7 and Table 8.
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
4.3. Route Projection Options 6.3. Via Information Options
An RPO signals the ordered list of IPv6 Via Addresses that An Via Option signals the ordered list of IPv6 Via Addresses that
constitutes the hops of either a Serial Track or a Segment of a more 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 Complex Track. An Via Option MUST contain at least one Via Address,
Via Address MUST NOT be present more than once, otherwise the RPO and a Via Address MUST NOT be present more than once, otherwise the
MUST be ignored. The format of the RPOs is as follows: Via Option MUST be ignored. The format of the Via Options 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 10, line 44 skipping to change at page 13, line 33
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Via Address n . . Via Address n .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Route Projection Option format (uncompressed form) Figure 7: Via Information Option format (uncompressed form)
Option Type: 0x0B for VIO, 0x0C for SRVIO (to be confirmed by IANA) Option Type: 0x0B for SF-VIO, 0x0C for SR-VIO (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.
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. The value of 0 the main DODAG as indicated by the TrackID field. The value of 0
is 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. starts at 255.
When the Root of the DODAG needs to refresh or update a Segment in When the Root of the DODAG needs to refresh or update a Segment in
a Track, it increments the Segment Sequence individually for that a Track, it increments the Segment Sequence individually for that
Segment. Segment.
The Segment information indicated in the RPO deprecates any state The Segment information indicated in the Via Option deprecates any
for the Segment indicated by the SegmentID within the indicated state for the Segment indicated by the SegmentID within the
Track and sets up the new information. indicated Track and sets up the new information.
An RPO with a Segment Sequence that is not as fresh as the current An Via Option with a Segment Sequence that is not as fresh as the
one is ignored. current one is ignored.
An RPO for a given Track Egress with the same (TrackID, SegmentID, A VIO for a given DODAGID with the same (TrackID, SegmentID,
Segment Sequence) indicates a retry; it MUST NOT change the Segment Sequence) indicates a retry; it MUST NOT change the
Segment and MUST be propagated or answered as the first copy. 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. Segment is usable.
The period starts when a new Segment Sequence is seen. The value The period starts when a new Segment Sequence is seen. The value
of 255 (0xFF) represents infinity. The value of zero (0x00) of 255 (0xFF) represents infinity. The value of zero (0x00)
indicates a loss of reachability. indicates a loss of reachability.
A P-DAO message that contains a Via Information option with a A P-DAO message that contains a Via Information option with a
Segment Lifetime of zero for a Track Egress is referred as a No- Segment Lifetime of zero is referred as a No-Path P-DAO in this
Path (for that Track Egress) in this document. document.
SRH-6LoRH header: The first 2 bytes of the (first) SRH-6LoRH as 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 shown in Figure 6 of [RFC8138]. A 6LoRH Type of 4 means that the
VIA Addresses are provided in full with no compression. VIA Addresses are provided in full with no compression.
Via Address: An IPv6 addresse along the Segment. Via Address: An IPv6 addresse along the Segment.
In a VIO, the list is a strict path between direct neighbors, In a SF-VIO, the list is a strict path between direct neighbors,
whereas for an SRVIO, the list may be loose, provided that each from the segment ingress to egress, both included. In an SR-VIO,
listed node has a path to the next listed node, e.g., via another the list starts at the first hop and ends at a Track Egress. The
list in an SR-VIO may be loose, provided that each listed node has
a path to the next listed node, e.g., via a segment or another
Track. Track.
In the case of a SMPR, or if [RFC8138] is not used in the data In the case of a SF-VIO, or if [RFC8138] is not used in the data
packets, then the Root MUST use only one SRH-6LoRH per RPO, and packets, then the Root MUST use only one SRH-6LoRH per Via Option,
the compression is the same for all the addresses, as shown in and the compression is the same for all the addresses, as shown in
Figure 5. Figure 7.
In case of a NMPR, and if [RFC8138] is in use in the main DODAG, In case of an SR-VIO, and if [RFC8138] is in use in the main
then the Root SHOULD optimize the size of the SRVIO; more than one DODAG, then the Root SHOULD optimize the size of the SR-VIO; more
SRH-6LoRH may be present, e.g., if the compression level changes than one SRH-6LoRH may be present, e.g., if the compression level
inside the Segment and different SRH-6LoRH Types are required. changes inside the Segment and different SRH-6LoRH Types are
required. The content of the SR-VIO starting at the first SRH-
6LoRH header is thus verbatim the one that the Track Ingress
places in the packet encapsulation to reach the Track Ingress.
4.4. Sibling Information Option 6.4. 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. One or more that could be used by the Root to form Projected Routes. One or more
SIO(s) may be placed in the DAO messages that are sent to the Root in SIO(s) may be placed in the DAO messages that are sent to the Root in
Non-Storing Mode. Non-Storing Mode.
The format of the SIO is as follows: 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
skipping to change at page 12, line 48 skipping to change at page 15, line 38
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Sibling Address . . Sibling Address .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Sibling Information Option Format Figure 8: Sibling Information Option Format
Option Type: 0x0D (to be confirmed by IANA) Option Type: 0x0D (to be confirmed by IANA)
Option Length: In bytes, the size of the option. Option Length: In bytes, the size of the option.
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 and corresponds to the compression used for the Sibling Address and
its DODAGID if resent. The Compression refernce is the Root of its DODAGID if resent. The Compression refernce is the Root of
the main DODAG. the main DODAG.
skipping to change at page 14, line 5 skipping to change at page 16, line 44
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.
5. Projected DAO 7. 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 main DODAG
projects a Track by sending one or more Projected-DAO (P-DAO) installs a Track as a collection of Projected Routes, using a
messages to selected routers in the DODAG. The P-DAO signals a Projected-DAO (P-DAO) message to maintain each individual route. The
collection of Targets in the RPL Target Option(s) (RTO). Those P-DAO signals a collection of Targets in the RPL Target Option(s)
Targets can be reached via a sequence of routers indicated in a Route (RTO). Those Targets can be reached via a sequence of routers
Projection Option (RPO). A P-DAO message MUST contain exactly one indicated in a Via Information Option (VIO). A P-DAO message MUST
RPO, which is either a VIO or an SRVIO, and MUST follow one or more contain exactly one VIO, which is either a SF-VIO or an SR-VIO, and
RTOs. There can be at most one such sequence of RTO(s) and an RPO. MUST follow one or more RTOs. There can be at most one such sequence
of RTO(s) and an Via Option. A track is indentified by a tupple
DODAGID, TrackID and each route within a Track is indexed by a
SegmentID.
A P-DAO MUST be sent from the address of the Root that serves as A P-DAO MUST be sent from the address of the Root that serves as
DODAGID for the main DODAG. It MUST be sent to a GUA or a ULA of DODAGID for the main DODAG. It MUST be sent to a GUA or a ULA of
either the ingress or the egress of the Segment, more below. If the 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 '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 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 message, using a DAO-ACK that MUST be sent back to the address that
serves as DODAGID for the main DODAG. 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 Via Option as opposed to the Path
from a TIO. Also, a Segment Lifetime of 0 in an RPO indicates that Sequence from a TIO. Also, a Segment Lifetime of 0 in an Via Option
the projected route associated to the Segment is to be removed. indicates that 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 5.4. A Non-Storing * The Non-Storing Mode is discussed in Section 7.5. A Non-Storing
Mode P-DAO carries an SRVIO with the loose list of Via Addresses Mode P-DAO carries an SR-VIO with the loose list of Via Addresses
that forms a source-routed Segment to the Track Egress. The that forms a source-routed Segment to the Track Egress. The
recipient of the P-DAO is the ingress router of the source-routed recipient of the P-DAO is the Track Ingress; it MUST install a
Segment. The ingress router MUST install a source-routed state to source-routed state to the Track Egress and reply to the Root
the Track Egress and reply to the Root directly using a DAO-ACK directly using a DAO-ACK message if requested to.
message if requested to.
* The Storing Mode is discussed in Section 5.5. A Storing Mode * The Storing Mode is discussed in Section 7.6. A Storing Mode
P-DAO carries a VIO with the strict list of Via Addresses from the P-DAO carries a SF-VIO with the strict list of Via Addresses from
ingress to the egress of the Segment in the data path order. The the ingress to the egress of the Segment in the data path order.
routers listed in the Via Addresses, except the egress, MUST The routers listed in the Via Addresses, except the egress, MUST
install a routing state to the Target(s) via the next Via Address install a routing state to the Target(s) via the next Via Address
in the VIO. In normal operations, the P-DAO is propagated along in the SF-VIO. In normal operations, the P-DAO is propagated
the chain of Via Routers from the egress router of the path till along the chain of Via Routers from the egress router of the path
the ingress one, which confirms the installation to the Root with till the ingress one, which confirms the installation to the Root
a DAO-ACK message. Note that the Root may be the ingress and it with a DAO-ACK message.
may be the egress of the Segment, that it can also be neither but
it 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 7.9). The Root can then modify or remove the Projected Section 9.12). 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]. [RFC4443].
The portion of the invoking packet that is sent back in the ICMP 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 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 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 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 not reach. if a 6LoWPAN Routing Header (6LoRH) [RFC8138] is used to
carry the IPv6 routing information in the outer header then that carry the IPv6 routing information in the outer header then that
whole 6LoRH information SHOULD be present in the ICMP message. whole 6LoRH information SHOULD be present in the ICMP message.
The sender and exact operation depend on the Mode and is described in The sender and exact operation depend on the Mode and is described in
Section 5.4 and Section 5.5 respectively. Section 7.5 and Section 7.6 respectively.
5.1. Requesting a Track 7.1. Requesting a Track
A Node is free to ask the Root for a new Track at any time. This is A Node is free to ask the Root for a new Track at any time. This is
done with a PDR message, that indicates in the Requested Lifetime done with a PDR message, that indicates in the Requested Lifetime
field the duration for which the Track should be established. Upon a field the duration for which the Track should be established. Upon a
PDR, the Root MAY install the necessary Segments, in which case it PDR, the Root MAY install the necessary Segments, in which case it
answers with a PDR-ACK indicating the granted Track Lifetime. All answers with a PDR-ACK indicating the granted Track Lifetime. All
the Segments MUST be of a same mode, either Storing or Non-Storing. 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 All the Segments MUST be created with the same TrackID and the same
Track Egress signaled in the P-DAO. DODAGID signaled in the P-DAO.
The Root is free to design the Track as it wishes, and to change the The Root is free to design the Track as it wishes, and to change the
Segments overtime to serve the Track as needed, without notifying the Segments overtime to serve the Track as needed, without notifying the
resquesting Node. The Segment Lifetime in the P-DAO messages does resquesting Node. The Segment Lifetime in the P-DAO messages does
not need to be aligned to the Requested Lifetime in the PDR, or not need to be aligned to the Requested Lifetime in the PDR, or
between P-DAO messages for different Segments. The Root may use between P-DAO messages for different Segments. The Root may use
shorter lifetimes for the Segments and renew them faster than the 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 Track is, or longer lifetimes in which case it will need to tear down
the Segments if the Track is not renewed. the Segments if the Track is not renewed.
When the Track Lifetime that was returned in the PDR-ACK is close to 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 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 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. will time out and the Root will tear down the whole structure.
If the Track fails and cannot be restored, the Root notifies the If the Track fails and cannot be restored, the Root notifies the
resquesting Node asynchronously with a PDR-ACK with a Track Lifetime resquesting Node asynchronously with a PDR-ACK with a Track Lifetime
of 0, indicating that the Track has failed, and a PDR-ACK Status of 0, indicating that the Track has failed, and a PDR-ACK Status
indicating the reason of the fault. indicating the reason of the fault.
5.2. Identifying a Track 7.2. Identifying a Track
RPL defines the concept of an Instance to signal an individual RPL defines the concept of an Instance to signal an individual
routing topology but does not have a concept of an administrative routing topology but does not have a concept of an administrative
distance, which exists in certain proprietary implementations to sort distance, which exists in certain proprietary implementations to sort
out conflicts between multiple sources of routing information within out conflicts between multiple sources of routing information within
one routing topology. one routing topology.
This draft leverages the RPL Instance model as follows: This draft leverages the RPL Instance model as follows:
* The Root MAY use P-DAO messages to add better routes in the main * The Root MAY use P-DAO messages to add better routes in the main
skipping to change at page 16, line 30 skipping to change at page 19, line 22
see Appendix A.1. see Appendix A.1.
When adding an SMPR to the main RPL Instance, the Root MUST set 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. 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 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 DODAGID field. A Projected Route provides a longer match to
the Target Address than the default route via the Root, so it is the Target Address than the default route via the Root, so it is
preferred. preferred.
Once the Projected Route is installed, the intermediate nodes Once the Projected Route is installed, the intermediate nodes
listed in the VIO after first one (i.e. The ingress) can be listed in the SF-VIO after first one (i.e. The ingress) can be
elided from the RH in packets sent along the Segment signaled in elided from the RH in packets sent along the Segment signaled in
the P-DAO. The resulting loose source routing header indicates the P-DAO. The resulting loose source routing header indicates
(one of) the Target(s) as the next entry after the ingress. (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, * 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 Traffic Engineered) path as a Serial or as a Complex Track, to a
particular endpoint that is the Track Egress. In that case, the particular endpoint that is the Track Egress. In that case, the
Root MUST install a Local RPL Instance (see section 5 of [RPL]). 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 In a that case, the TrackID MUST be unique for the Global Unique
IPv6 Address (GUA) or Unique-Local Address (ULA) of the Track IPv6 Address (GUA) or Unique-Local Address (ULA) of the Track
Egress that serves as DODAGID for the Track. This way, a Track is Ingress that serves as DODAGID for the Track. This way, a Track
uniquely identified by the tuple (Track Egress Address, TrackID) is uniquely identified by the tuple (DODAGID, TrackID) where the
where the TrackID is always represented with the 'D' flag set. TrackID is always represented with the 'D' flag set to 0.
The Track Egress Address and the TrackID MUST be signaled in the The Track Egress Address and the TrackID MUST be signaled in the
P-DAO message as shown in Figure 1. P-DAO message as shown in Figure 1.
5.3. Forwarding Along a Track 7.3. Installing a Track
Sending a Packet within a RPL Local Instance requires the presence of A Storing Mode P-DAO contains an SF-VIO that signals the strict
an RPL Packet Information (RPI) (see [USEofRPLinfo]) in the outer sequence of consecutive nodes to form a segment between a segment
IPv6 Header chain. The RPI carries a local RPLInstanceID which, in ingress and a segment egress (both included). It installs a route of
association with the IPv6 final destination, indicates the RPL a higher precedence along the segment towards the Targets indicated
Instance that the packet follows. in the Target Options. The segment is included in a DODAG indicated
by the P-DAO Base Object, that may be the one formed by the main RPL
Instance, or a Track associated with a local RPL Instance. A Track
Egress is signaled as a Target in the P-DAO, and as the last entry is
an SF-VIO of a last segment towards that Egress.
A Non-Storing Mode P-DAO signals a strict or loose sequence of nodes
between the Track Ingress (excluded) and a Track Egress (included).
It installs a source-routed path of a higher precedence within the
Track indicated by the P-DAO Base Object, towards the Targets
indicated in the Target Options. The source-routed path requires a
Source-Routing header which implies an encapsulation to add the SRH
to an existing packet.
The next entry in the sequence must be either a neighbor of the
previous entry, or reachable as a Target via another Projected Route,
either Storing or Non-Storing. If it is reachable over a Storing
Mode Projected Route, the next entry in the loose sequence is the
Target of a previous segment and the ingress of a next segment; the
segments are associated with the same Track, which avoids the need of
an encapsulation. Conversely, if it is reachable over a Non-Storing
Mode Projected Route, the next loose source routed hop of the inner
Track is a Target of a previous Track and the ingress of a next
Track, which requires a de- and a re-encapsulation.
A Serial Track is installed by a single Projected Routes that signals
the sequence of consecutive nodes, either in Storing or Non-Storing
Mode. If can be a loose Non-Storing Mode Projected Route, in which
case the next loose entry must recursively be reached over a Serial
Track.
A Complex Track can be installed as a collection of Projected Routes
with the same DODAGID and Track ID. The Ingress of a Non-Storing
Mode Projected Route must be the owner of the DODAGID. The Ingress
of a Storing Mode Projected Route must be either the owner of the
DODAGID, or the egress of a preceding Storing Mode Projected Route in
the same Track. In the latter case, the Targets of the Projected
Route must be Targets of the preceding Projected Route to ensure that
they are visible from the track Ingress.
7.4. Forwarding Along a Track
This draft leverages the RPL Forwarding model follows: This draft leverages the RPL Forwarding model follows:
* The RPI carries a local RPLInstanceID called the TrackID, which, * In the data packets, the Track DODAGID and the TrackID MUST be
in association with the IPv6 final destination, indicates the respectively signaled as the IPv6 Source Address and the
Track along which the packet is forwarded. The 'D' flag in the RPLInstanceID field of the RPI that MUST be placed in the outer
RPLInstanceID MUST be set to indicate that the final destination chain of IPv6 Headers.
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 The RPI carries a local RPLInstanceID called the TrackID, which,
be respectively signaled as the IPv6 Address of the final in association with the DODAGID, indicates the Track along which
destination and the RPLInstanceID field of the RPI that MUST be the packet is forwarded.
placed in the outer chain of IPv6 Headers.
In case of a NMPR, the outer chain of IPv6 Headers contains an The 'D' flag in the RPLInstanceID MUST be set to 0 to indicate
IPv6 RH as well. If it is not fully consumed, then the final that the source address in the IPv6 header is set ot the DODAGID,
destination is the last entry in the RH; else it is the more in Section 7.4.
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 * This draft conforms the principles of [USEofRPLinfo] with regards
Egress is the destination of the packet, there is no need for an to packet forwarding and encapsulation along a Track.
encapsulation. Else, i.e., if the Track Ingress is forwarding a
packet into the Track, or if the the final destination is reached - In that case, the Track is the DODAG, the Track Ingress is the
over the Track via the Track Egress but is located beyond it, then Root, and the Track Egress is a RAL, and neighbors of the Track
an IP-in-IP encapsulation is needed. Egress that can be reached via the Track are RULs. The
encapsulation rules in [USEofRPLinfo] apply.
- 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.
- So the Track Ingress must encapsulate the traffic that it did
not originate, and add an RPI in any fashion.
A packet that is being routed over the RPL Instance associated to A packet that is being routed over the RPL Instance associated to
a first Non-Storing Mode Track MAY be placed (encapsulated) in a 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 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 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 it placed in a Storing Mode Track MUST follow that Track till the
Track Egress. Track Egress.
When a Track Egress extracts a packet from a Track (decapsulates When a Track Egress extracts a packet from a Track (decapsulates
the packet), the Destination of the inner packet MUST be either the packet), the Destination of the inner packet MUST be either
this node or a direct neighbor, or a Target of another Segment of this node or a direct neighbor, or a Target of another Segment of
the same Track for which this node is ingress, otherwise the the same Track for which this node is ingress, otherwise the
packet MUST be dropped. packet MUST be dropped.
All properties of a Track operations are inherited form the main RPL 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 Instance that is used to install the Track. For instance, the use of
compression per [RFC8138] is determined by whether it is used in the compression per [RFC8138] is determined by whether it is used in the
main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the main instance, e.g., by setting the "T" flag [TURN-ON_RFC8138] in the
RPL configuration option. RPL configuration option.
5.4. Non-Storing Mode Projected Route 7.5. Non-Storing Mode Projected Route
As illustrated in Figure 7, a P-DAO that carries an SRVIO enables the As illustrated in Figure 9, a P-DAO that carries an SR-VIO enables
Root to install a source-routed path towards a Track Egress in any the Root to install a source-routed path towards a Track Egress in
particular router. any particular router.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ | P ^ ACK +-----+ | P ^ ACK
| Track | DAO | | Track | DAO |
o o o o Ingress X V | X o o o o Ingress X V | X
skipping to change at page 18, line 38 skipping to change at page 22, line 26
o o ° o o o o X o X Segment o o ° o o o o X o X Segment
o o o o o o o o X Track X o o o o o o o o X Track X
o o o o o Egress o o o o o Egress
o o o o o o o o
o o o o o o o o
destination destination
LLN LLN
Figure 7: Projecting a Non-Storing Route Figure 9: Projecting a Non-Storing Route
A route indicated by an SRVIO may be loose, meaning that the node A route indicated by an SR-VIO 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. source routing and other mechanisms may effectively cause loops.
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. set to the Track Egress.
In order to signal the Segment, the router encapsulates the packet In order to signal the Segment, the router encapsulates the packet
with an IP-in-IP header and a Routing Header as follows: with an IP-in-IP header and a Routing Header as follows:
* In the uncompressed form the source of the packet is this router, * In the uncompressed form the source of the packet is this router,
the destination is the first Via Address in the SRVIO, and the RH the destination is the first Via Address in the SR-VIO, and the RH
is a Source Routing Header (SRH) [RFC6554] that contains the list is a Source Routing Header (SRH) [RFC6554] that contains the list
of the remaining Via Addresses terminating by the Track Egress. of the remaining Via Addresses terminating by the Track Egress.
* The preferred alternate in a network where 6LoWPAN Header * The preferred alternate in a network where 6LoWPAN Header
Compression [RFC6282] is used is to leverage "IPv6 over Low-Power Compression [RFC6282] is used is to leverage "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch" Wireless Personal Area Network (6LoWPAN) Paging Dispatch"
[RFC8025] to compress the RPL artifacts as indicated in [RFC8138]. [RFC8025] to compress the RPL artifacts as indicated in [RFC8138].
In that case, the source routed header is the exact copy of the 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 (chain of) SRH-6LoRH found in the SR-VIO, also terminating by the
Track Egress. The RPI-6LoRH is appended next, followed by an IP- Track Egress. The RPI-6LoRH is appended next, followed by an IP-
in-IP 6LoRH Header that indicates the Ingress Router in the in-IP 6LoRH Header that indicates the Ingress Router in the
Encapsulator Address field, see as a similar case Figure 20 of Encapsulator Address field, see as a similar case Figure 20 of
[TURN-ON_RFC8138]. [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 another Track to the loose packet is forwarded to that neighbor, or another Track to the loose
next hop for which this node is Ingress; in the latter case, another next hop for which this node is Ingress; in the latter case, another
encapsulation takes place and the process possibly recurses; encapsulation takes place and the process possibly recurses;
skipping to change at page 19, line 38 skipping to change at page 23, line 28
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.
5.5. Storing Mode Projected Route 7.6. Storing Mode Projected Route
As illustrated in Figure 8, a P-DAO that carries a VIO enables the As illustrated in Figure 10, a P-DAO that carries a SF-VIO enables
Root to install a stateful route towards a collection of Targets the Root to install a stateful route towards a collection of Targets
along a Segment between a Track Ingress and a Track Egress. along a Segment between a Track Ingress and a Track Egress.
------+--------- ------+---------
| 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 10: 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 ,
the Root sends a unicast P-DAO message to the Track Egress router of the Root sends a unicast P-DAO message to the Track Egress router of
the routing Segment that is being installed. The P-DAO message the routing Segment that is being installed. The P-DAO message
contains a VIO with the direct sequence of Via Addresses. The VIO contains a SF-VIO with the direct sequence of Via Addresses. The SF-
follows one or more RTOs indicating the Targets to which the Track VIO follows one or more RTOs indicating the Targets to which the
leads. The VIO contains a Segment Lifetime for which the state is to Track leads. The SF-VIO contains a Segment Lifetime for which the
be maintained. 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 SF-VIO. This is how the egress recognizes its role.
a similar fashion, the ingress node recognizes its role as it matches In a similar fashion, the ingress node recognizes its role as it
first Via Address in the VIO. matches first Via Address in the SF-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. If one of the already able to route to the Target(s) on its own. If one of the
Targets is not known, the node MUST answer to the Root with a Targets is not known, the node MUST answer to the Root with a
negative DAO-ACK listing the Target(s) that could not be located negative DAO-ACK listing the Target(s) that could not be located
(suggested status 10 to be confirmed by IANA). (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
skipping to change at page 21, line 12 skipping to change at page 24, line 40
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 Address the precedes the propagated DAO message is found in the Via Address the precedes the
one that contain the address of the propagating node, which is used one that contain the address of the propagating node, which is used
as source of the message. as source of the message.
Upon receiving a propagated DAO, all except the Egress Router MUST Upon receiving a propagated DAO, all except the Egress Router MUST
install a route towards the DAO Target(s) via their successor in the install a route towards the DAO Target(s) via their successor in the
VIO. The router MAY install additional routes towards the VIA SF-VIO. The router MAY install additional routes towards the VIA
Addresses that are the VIO after the next one, if any, but in case of Addresses that are the SF-VIO after the next one, if any, but in case
a conflict or a lack of resource, the route(s) to the Target(s) have of a conflict or a lack of resource, the route(s) to the Target(s)
precedence. have precedence.
If a router cannot reach its predecessor in the VIO, the router MUST If a router cannot reach its predecessor in the SF-VIO, the router
answer to the Root with a negative DAO-ACK indicating the successor MUST answer to the Root with a negative DAO-ACK indicating the
that is unreachable (suggested status 11 to be confirmed by IANA). successor that is unreachable (suggested status 11 to be confirmed by
IANA).
The process continues till the P-DAO is propagated to ingress router The process continues till the P-DAO is propagated to ingress router
of the Segment, which answers with a DAO-ACK to the Root. of the Segment, which answers with a DAO-ACK to the Root.
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 an SMPR, the node that fails to In case of a forwarding error along an SMPR, the node that fails to
forward SHOULD send an ICMP error with a code "Error in Projected forward SHOULD send an ICMP error with a code "Error in Projected
Route" to the Root. Failure to do so may result in packet loss and Route" to the Root. Failure to do so may result in packet loss and
wasted resources along the Projected Route that is broken. wasted resources along the Projected Route that is broken.
6. Security Considerations 8. 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?
7. IANA Considerations 9. IANA Considerations
7.1. New RPL Control Codes 9.1. New Elective 6LoWPAN Routing Header Type
This document updates the IANA registry titled "Elective 6LoWPAN
Routing Header Type" that was created for [RFC8138] and assigns the
following value:
+=======+=============+===============+
| Value | Description | Reference |
+=======+=============+===============+
| 7 | P-RPI-6LoRH | This document |
+-------+-------------+---------------+
Table 1: New Elective 6LoWPAN
Routing Header Type
9.2. New Critical 6LoWPAN Routing Header Type
This document updates the IANA registry titled "Critical 6LoWPAN
Routing Header Type" that was created for [RFC8138] and assigns the
following value:
+=======+=============+===============+
| Value | Description | Reference |
+=======+=============+===============+
| 7 | P-RPI-6LoRH | This document |
+-------+-------------+---------------+
Table 2: New Critical 6LoWPAN
Routing Header Type
9.3. New Subregistry For The RPL Option Flags
IANA is required to create a subregistry for the 8-bit RPL Option
Flags field, as detailed in Figure 2, under the "Routing Protocol for
Low Power and Lossy Networks (RPL)" registry. The bits are indexed
from 0 (leftmost) to 7. Each bit is tracked with the following
qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Indication When Set
* Reference
Registration procedure is "Standards Action" [RFC8126]. The initial
allocation is as indicated in Table 6:
+============+======================+===============+
| Bit number | Indication When Set | Reference |
+============+======================+===============+
| 0 | Down 'O' | [RFC6553] |
+------------+----------------------+---------------+
| 1 | Rank-Error (R) | [RFC6553] |
+------------+----------------------+---------------+
| 2 | Forwarding-Error (F) | [RFC6553] |
+------------+----------------------+---------------+
| 3 | Projected-Route (P) | This document |
+------------+----------------------+---------------+
Table 3: Initial PDR Flags
9.4. 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 4:
+======+=============================+===============+ +======+=============================+===============+
| 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 4: New RPL Control Codes
7.2. New RPL Control Message Options 9.5. 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 5:
+=======+======================================+===============+ +=======+==========================================+===============+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+======================================+===============+ +=======+==========================================+===============+
| 0x0B | Via Information option | This document | | 0x0B | Stateful Via Information option (SF-VIO) | This document |
+-------+--------------------------------------+---------------+ +-------+------------------------------------------+---------------+
| 0x0C | Source-Routed Via Information option | This document | | 0x0C | Source-Routed Via Information option | This document |
+-------+--------------------------------------+---------------+ | | (SR-VIO) | |
| 0x0D | Sibling Information option | This document | +-------+------------------------------------------+---------------+
+-------+--------------------------------------+---------------+ | 0x0D | Sibling Information option | This document |
+-------+------------------------------------------+---------------+
Table 2: RPL Control Message Options Table 5: RPL Control Message Options
7.3. SubRegistry for the Projected DAO Request Flags 9.6. 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
Registration procedure is "Standards Action" [RFC8126]. The initial Registration procedure is "Standards Action" [RFC8126]. The initial
allocation is as indicated in Table 3: allocation is as indicated in Table 6:
+============+========================+===============+ +============+========================+===============+
| 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 6: Initial PDR Flags
7.4. SubRegistry for the PDR-ACK Flags 9.7. 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.
7.5. Subregistry for the PDR-ACK Acceptance Status Values 9.8. 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 7:
+-------+------------------------+---------------+ +-------+------------------------+---------------+
| 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 7: Acceptance values of the PDR-ACK Status
7.6. Subregistry for the PDR-ACK Rejection Status Values 9.9. 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 8:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| 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 8: Rejection values of the PDR-ACK Status
7.7. SubRegistry for the Route Projection Options Flags 9.10. SubRegistry for the Via Information 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 Via
Projection Options (RPO) Flags field. Each bit is tracked with the Information Options (Via Option) Flags field. Each bit is tracked
following qualities: 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 Route Projection Options (RPO) Flags. currently defined for the Via Information Options (Via Option) Flags.
7.8. SubRegistry for the Sibling Information Option Flags 9.11. 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
Registration procedure is "Standards Action" [RFC8126]. The initial Registration procedure is "Standards Action" [RFC8126]. The initial
allocation is as indicated in Table 6: allocation is as indicated in Table 9:
+============+===================================+===============+ +============+===================================+===============+
| 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 9: Initial SIO Flags
7.9. Error in Projected Route ICMPv6 Code 9.12. 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.
8. Acknowledgments 10. 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.
9. Normative References 11. 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,
skipping to change at page 26, line 8 skipping to change at page 31, line 8
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
[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>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012,
<https://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012, DOI 10.17487/RFC6554, March 2012,
<https://www.rfc-editor.org/info/rfc6554>. <https://www.rfc-editor.org/info/rfc6554>.
[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>.
10. Informative References 12. 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 26, line 46 skipping to change at page 32, line 4
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", Work in Progress, Internet-Draft, of IEEE 802.15.4", Work in Progress, Internet-Draft,
draft-ietf-6tisch-architecture-29, 27 August 2020, draft-ietf-6tisch-architecture-29, 27 August 2020,
<https://tools.ietf.org/html/draft-ietf-6tisch- <https://tools.ietf.org/html/draft-ietf-6tisch-
architecture-29>. architecture-29>.
[RAW-ARCHI] [RAW-ARCHI]
Thubert, P., Papadopoulos, G., and R. Buddenberg, Thubert, P., Papadopoulos, G., and R. Buddenberg,
"Reliable and Available Wireless Architecture/Framework", "Reliable and Available Wireless Architecture/Framework",
Work in Progress, Internet-Draft, draft-pthubert-raw- Work in Progress, Internet-Draft, draft-pthubert-raw-
architecture-04, 6 July 2020, architecture-05, 15 November 2020,
<https://tools.ietf.org/html/draft-pthubert-raw- <https://tools.ietf.org/html/draft-pthubert-raw-
architecture-04>. architecture-05>.
[TURN-ON_RFC8138] [TURN-ON_RFC8138]
Thubert, P. and L. Zhao, "A RPL DODAG Configuration Option Thubert, P. and L. Zhao, "A RPL DODAG Configuration Option
for the 6LoWPAN Routing Header", Work in Progress, for the 6LoWPAN Routing Header", Work in Progress,
Internet-Draft, draft-ietf-roll-turnon-rfc8138-17, 30 Internet-Draft, draft-ietf-roll-turnon-rfc8138-17, 30
September 2020, <https://tools.ietf.org/html/draft-ietf- September 2020, <https://tools.ietf.org/html/draft-ietf-
roll-turnon-rfc8138-17>. 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,
skipping to change at page 27, line 31 skipping to change at page 32, line 34
[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-41, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-42,
21 September 2020, <https://tools.ietf.org/html/draft- 12 November 2020, <https://tools.ietf.org/html/draft-ietf-
ietf-roll-useofrplinfo-41>. roll-useofrplinfo-42>.
[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 11.
In that mode, a RPL node indicates a parent-child relationship to the In that mode, a RPL node indicates a parent-child relationship to the
Root, using a Destination Advertisement Object (DAO) that is unicast Root, using a Destination Advertisement Object (DAO) that is unicast
from the node directly to the Root, and the Root typically builds a from the node directly to the Root, and the Root typically builds a
source routed path to a destination down the DODAG by recursively source routed path to a destination down the DODAG by recursively
concatenating this information. concatenating this information.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
skipping to change at page 28, line 21 skipping to change at page 33, line 21
+-----+ ^ | | +-----+ ^ | |
| | DAO | ACK | | | DAO | ACK |
o o o o | | | Strict o o o o | | | Strict
o o o o o o o o o | | | Source o o o o o o o o o | | | Source
o o o o o o o o o o | | | Route o o o o o o o o o o | | | Route
o o o o o o o o o | | | o o o o o o o o o | | |
o o o o o o o o | v v o o o o o o o o | v v
o o o o o o o o
LLN LLN
Figure 9: RPL Non-Storing Mode of operation Figure 11: RPL Non-Storing Mode of operation
Based on the parent-children relationships expressed in the non- Based on the parent-children relationships expressed in the non-
storing DAO messages,the Root possesses topological information about storing DAO messages,the Root possesses topological information about
the whole network, though this information is limited to the the whole network, though this information is limited to the
structure of the DODAG for which it is the destination. A packet structure of the DODAG for which it is the destination. A packet
that is generated within the domain will always reach the Root, which that is generated within the domain will always reach the Root, which
can then apply a source routing information to reach the destination can then apply a source routing information to reach the destination
if the destination is also in the DODAG. Similarly, a packet coming if the destination is also in the DODAG. Similarly, a packet coming
from the outside of the domain for a destination that is expected to from the outside of the domain for a destination that is expected to
be in a RPL domain reaches the Root. be in a RPL domain reaches the Root.
skipping to change at page 29, line 36 skipping to change at page 34, line 36
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 12:
* In Storing Mode, unless the destination is a child of the source, * In Storing Mode, unless the destination is a child of the source,
the packets will follow the default route up the DODAG as well. the packets will follow the default route up the DODAG as well.
If the destination is in the same DODAG, they will eventually If the destination is in the same DODAG, they will eventually
reach a common parent that has a route to the destination; at reach a common parent that has a route to the destination; at
worse, the common parent may also be the Root. From that common worse, the common parent may also be the Root. From that common
parent, the packet will follow a path down the DODAG that is parent, the packet will follow a path down the DODAG that is
optimized for the Objective Function that was used to build the optimized for the Objective Function that was used to build the
DODAG. DODAG.
skipping to change at page 30, line 21 skipping to change at page 35, line 21
+-----+ +-----+
X X
^ v o o ^ v o o
^ o o v o o o o o ^ o o v o o o o o
^ o o o v o o o o o ^ o o o v o o o o o
^ o o v o o o o o ^ o o v o o o o o
S o o o D o o o S o o o D o o o
o o o o o o o o
LLN LLN
Figure 10: Routing Stretch between S and D via common parent X Figure 12: Routing Stretch between S and D via common parent X
It results that it is often beneficial to enable transversal P2P It results that it is often beneficial to enable transversal P2P
routes, either if the RPL route presents a stretch from shortest routes, either if the RPL route presents a stretch from shortest
path, or if the new route is engineered with a different objective, path, or if the new route is engineered with a different objective,
and that it is even more critical in Non-Storing Mode than it is in and that it is even more critical in Non-Storing Mode than it is in
Storing Mode, because the routing stretch is wider. For that reason, Storing Mode, because the routing stretch is wider. For that reason,
earlier work at the IETF introduced the "Reactive Discovery of earlier work at the IETF introduced the "Reactive Discovery of
Point-to-Point Routes in Low Power and Lossy Networks" [RFC6997], Point-to-Point Routes in Low Power and Lossy Networks" [RFC6997],
which specifies a distributed method for establishing optimized P2P which specifies a distributed method for establishing optimized P2P
routes. This draft proposes an alternate based on a centralized routes. This draft proposes an alternate based on a centralized
skipping to change at page 30, line 50 skipping to change at page 35, line 50
+-----+ +-----+
| |
o o o o o o o o
o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o
S>>A>>>B>>C>>>D o o o S>>A>>>B>>C>>>D o o o
o o o o o o o o
LLN LLN
Figure 11: Projected Transversal Route Figure 13: Projected Transversal Route
This specification enables to store source-routed or Storing Mode This specification enables to store source-routed or Storing Mode
state in intermediate routers, which enables to limit the stretch of state in intermediate routers, which enables to limit the stretch of
a P2P route and maintain the characteristics within a given SLA. An a P2P route and maintain the characteristics within a given SLA. An
example of service using this mechanism oculd be a control loop that example of service using this mechanism oculd be a control loop that
would be installed in a network that uses classical RPL for would be installed in a network that uses classical RPL for
asynchronous data collection. In that case, the P2P path may be asynchronous data collection. In that case, the P2P path may be
installed in a different RPL Instance, with a different objective installed in a different RPL Instance, with a different objective
function. function.
 End of changes. 116 change blocks. 
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