draft-ietf-roll-dao-projection-06.txt   draft-ietf-roll-dao-projection-07.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550, 6553, 8138 (if approved) R. Jadhav Updates: 6550 (if approved) R.A. Jadhav
Intended status: Standards Track Huawei Tech Intended status: Standards Track Huawei Tech
Expires: November 25, 2019 M. Gillmore Expires: 6 May 2020 M. Gillmore
Itron Itron
J. Pylakutty 3 November 2019
Cisco
May 24, 2019
Root initiated routing state in RPL Root initiated routing state in RPL
draft-ietf-roll-dao-projection-06 draft-ietf-roll-dao-projection-07
Abstract Abstract
This document extends RFC 6550, RFC 6553 and RFC 8138 and enable to This document proposes a protocol extension to RPL that enables to
install a limited amount of centrally-computed routes in a RPL graph, install a limited amount of centrally-computed routes in a RPL graph,
enabling loose source routing down a non-storing mode DODAG, or enabling loose source routing down a non-storing mode DODAG, or
transversal routes inside the DODAG. In constrast with classical transversal routes inside the DODAG. As opposed to the classical
routes in RPL that are injected by the end devices, this draft route injection in RPL that are injected by the end devices, this
enables the root of the DODAG to projects the routes that are needed draft enables the Root of the DODAG to projects the routes that are
on the nodes where they should be installed. needed on the nodes where they should be installed.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 25, 2019. This Internet-Draft will expire on 6 May 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Subset of a 6LoWPAN Glossary . . . . . . . . . . . . . . 4
2.3. References . . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Other Terms . . . . . . . . . . . . . . . . . . . . . . . 5
3. Extending RFC 6550 . . . . . . . . . . . . . . . . . . . . . 4 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. RPL Instances . . . . . . . . . . . . . . . . . . . . . . 5 3. Extending RFC 6550 . . . . . . . . . . . . . . . . . . . . . 5
3.2. New RPL Control Message Options . . . . . . . . . . . . . 5 4. Identifying a Path . . . . . . . . . . . . . . . . . . . . . 6
3.3. RPI for Projected Routes . . . . . . . . . . . . . . . . 7 5. New RPL Control Messages and Options . . . . . . . . . . . . 7
3.4. Projected DAO . . . . . . . . . . . . . . . . . . . . . . 7 5.1. New P-DAO Request Control Message . . . . . . . . . . . . 7
3.4.1. Non-Storing Mode P-Route . . . . . . . . . . . . . . 9 5.2. New PDR-ACK Control Message . . . . . . . . . . . . . . . 8
3.4.2. Storing-Mode P-Route . . . . . . . . . . . . . . . . 10 5.3. Route Projection Options . . . . . . . . . . . . . . . . 8
4. Extending RFC 8138 . . . . . . . . . . . . . . . . . . . . . 13 5.4. Sibling Information Option . . . . . . . . . . . . . . . 10
4.1. Elective RPI 6LoRH . . . . . . . . . . . . . . . . . . . 13 6. Projected DAO . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Extending RFC 6553 . . . . . . . . . . . . . . . . . . . . . 13 6.1. Non-Storing Mode Projected Route . . . . . . . . . . . . 13
5.1. Uncompressed RPL Option . . . . . . . . . . . . . . . . . 13 6.2. Storing-Mode Projected Route . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7.1. New Elective 6LoWPAN Routing Header Type . . . . . . . . 14 8.1. New RPL Control Codes . . . . . . . . . . . . . . . . . . 17
7.2. New RPL Control Codes . . . . . . . . . . . . . . . . . . 15 8.2. Error in Projected Route ICMPv6 Code . . . . . . . . . . 18
7.3. Error in Projected Route ICMPv6 Code . . . . . . . . . . 15 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 10. Normative References . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 11. Informative References . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 16 Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . 17 A.1. Loose Source Routing in Non-storing Mode . . . . . . . . 20
Appendix A. Applications . . . . . . . . . . . . . . . . . . . . 18 A.2. Transversal Routes in storing and non-storing
A.1. Loose Source Routing in Non-storing Mode . . . . . . . . 18 modes . . . . . . . . . . . . . . . . . . . . . . . . . . 22
A.2. Transversal Routes in storing and non-storing modes . . . 19 Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 23
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 21 B.1. Using storing mode P-DAO in non-storing mode MOP . . . . 23
B.1. Using storing mode P-DAO in non-storing mode MOP . . . . 21 B.2. Projecting a storing-mode transversal route . . . . . . . 24
B.2. Projecting a storing-mode transversal route . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
The "Routing Protocol for Low Power and Lossy Networks" [RFC6550] The "Routing Protocol for Low Power and Lossy Networks" [RFC6550]
(LLN)(RPL) is a generic Distance Vector protocol that is well suited (LLN)(RPL) is a generic Distance Vector protocol that is well suited
low energy Internet of Things (IoT) networks. RPL forms Destination for application in a variety of low energy Internet of Things (IoT)
Oriented Directed Acyclic Graphs (DODAGs) in which the root often networks. RPL forms Destination Oriented Directed Acyclic Graphs
acts as the Border Router to connect the RPL domain to the Internet. (DODAGs) in which the Root often acts as the Border Router to connect
The root is responsible to select the RPL Instance that is used to the RPL domain to the Internet. The Root is responsible to select
forward a packet coming from the Internet into the RPL domain and set the RPL Instance that is used to forward a packet coming from the
the related RPL information in the packets. Internet into the RPL domain and set the related RPL information in
the packets.
The 6TiSCH architecture [I-D.ietf-6tisch-architecture] leverages RPL The 6TiSCH architecture [6TiSCH-ARCHI] leverages RPL for its routing
for its routing operation and considers the Deterministic Networking operation and considers the Deterministic Networking Architecture
Architecture [I-D.ietf-detnet-architecture] as one possible model [RFC8655] as one possible model whereby the device resources and
whereby the device resources and capabilities are exposed to an capabilities are exposed to an external controller which installs
external controller which installs routing states into the network routing states into the network based on some objective functions
based on some objective functions that reside in that external that reside in that external entity.
entity.
Based on heuristics of usage, path length, and knowledge of device Based on heuristics of usage, path length, and knowledge of device
capacity and available resources such as battery levels and capacity and available resources such as battery levels and
reservable buffers, a Path Computation Element ([PCE]) with a global reservable buffers, a Path Computation Element ([PCE]) with a global
visibility on the system could install additional P2P routes that are visibility on the system could install additional P2P routes that are
more optimized for the current needs as expressed by the objective more optimized for the current needs as expressed by the objective
function. function.
This draft enables a RPL root to install and maintain projected This draft enables a RPL Root to install and maintain Projected
routes (P-Routes) within its DODAG, along a selected set of nodes Routes within its DODAG, along a selected set of nodes that may or
that may or may not include self, for a chosen duration. This may not include self, for a chosen duration. This potentially
potentially enables routes that are more optimized than those enables routes that are more optimized than those obtained with the
obtained with the distributed operation of RPL, either in terms of distributed operation of RPL, either in terms of the size of a
the size of a source-route header or in terms of path length, which source-route header or in terms of path length, which impacts both
impacts both the latency and the packet delivery ratio. P-routes may the latency and the packet delivery ratio. Projected Routes may be
be installed in either Storing and Non-Storing Modes Instances of the installed in either Storing and Non-Storing Modes Instances of the
classical RPL operation, resulting in potentially hybrid situations classical RPL operation, resulting in potentially hybrid situations
where the mode of some P-routes is different from that of the other where the mode of some Projected Routes is different from that of the
routes in the RPL Instance. other routes in the RPL Instance.
P-Routes must be used with the parsimony to limit the amount of state Projected Routes must be used with the parsimony to limit the amount
that is installed in each device to fit within its resources, and to of state that is installed in each device to fit within its
limit the amount of rerouted traffic to fit within the capabilities resources, and to limit the amount of rerouted traffic to fit within
of the transmission links. The algorithm used to compute the paths the capabilities of the transmission links. The algorithm used to
and the protocol used to learn the topology of the network and the compute the paths and the protocol used to learn the topology of the
resources that are available in devices and in the network are out of network and the resources that are available in devices and in the
scope for this document. Possibly with the assistance of a Path network are out of scope for this document. Possibly with the
Computation Element ([PCE]) that could have a better visibility on assistance of a Path Computation Element ([PCE]) that could have a
the larger system, the root computes which segment could be optimized better visibility on the larger system, the Root computes which
and uses this draft to install the corresponding P-Routes. segment could be optimized and uses this draft to install the
corresponding Projected Routes.
2. Terminology A Projected Route may be a stand-alone path to a Target or a segment
in a complex Track [6TiSCH-ARCHI] that provides redundant forwarding
solutions to a destination to improve reliability and availability of
the wireless transmissions [RAW-PS].
2. Terminology
2.1. BCP 14 2.1. BCP 14
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. New Terms 2.2. Subset of a 6LoWPAN Glossary
P-Route: A route that is installed remotely by a RPL root. This document often uses the following acronyms:
2.3. References 6BBR: 6LoWPAN Backbone Router
6LBR: 6LoWPAN Border Router
6LN: 6LoWPAN Node
6LR: 6LoWPAN Router
DAD: Duplicate Address Detection
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement
NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol
NS: Neighbor Solicitation
RPL: IPv6 Routing Protocol for LLNs [RFC6550]
CMO: Control Message Option
DAO: Destination Advertisement Object
VIO: A Via Information Option, used in Storing Mode P-DAO messages.
SRVIO: A Source-Routed Via Information Option, used in Non-Storing
Mode P-DAO messages.
RPO: A Route Projection Option; it can be a VIO or an SRVIO.
P-DAO: A Projected DAO is a DAO message sent by the RPL Root to
install a Projected Route.
RTO: RPL Target Option
RAN: RPL-Aware Node
RA: Router Advertisement
RS: Router Solicitation
2.3. Other Terms
Projected Route: A Projected Route is a serial path that is computed
and installed remotely by a RPL Root.
Track: The term Track is used in this document to refer to a complex
path, e.g., a DODAG, that incorporates redundant Projected Routes
towards a destination for increased reliability, high availability
and load balancing.
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 following documents: discussed in the following documents:
o "Routing Protocol for Low Power and Lossy Networks" [RFC6550], and * "Routing Protocol for Low Power and Lossy Networks" [RFC6550], and
o "Terminology in Low power And Lossy Networks" [RFC7102]. * "Terminology in Low power And Lossy Networks" [RFC7102].
3. Extending RFC 6550 3. Extending RFC 6550
Section 6.7 of RPL [RFC6550] specifies Control Message Options (CMO) This specification introduces two new RPL Control Messages to enable
to be placed in RPL messages such as the Destination Advertisement a RPL Aware Node (RAN) to request the establisment of a path from
Object (DAO) message. The RPL Target Option and the Transit self to a Target. A RAN may request the installation of a path by
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 with a
completion status once it is done installing the path. See
Section 5.1 for more.
Section 6.7 of [RFC6550] specifies Control Message Options (CMO) to
be placed in RPL messages such as the Destination Advertisement
Object (DAO) message. The RPL Target Option (RTO) and the Transit
Information Option (TIO) are such options. In Non-Storing Mode, the Information Option (TIO) are such options. In Non-Storing Mode, the
TIO option is used in the DAO message to indicate the immediate TIO option is used in the DAO message to indicate a parent within a
parent of a given path. The TIO applies to the Target options that DODAG. The TIO applies to the RTOs that immedially preceed it in the
immedially preceed it. Options may be factorized; multiple TIOs may message. Options may be factorized; multiple TIOs may be present to
be present to indicate multiple routes to the one or more contiguous indicate multiple routes to the one or more contiguous addresses
addressed indicated in the Target Options that immediately precede indicated in the RTOs that immediately precede the TIOs in the RPL
the TIOs in the RPL message. message.
This specification introduces two new Control Message Options This specification introduces two new CMOs referred to as Route
referred to as Route Projection Options (RPO). One RPO is the Projection Options (RPO) to install Projected Routes. One RPO is the
Information option (VIO) and the other is the Source-Routed VIO Via Information Option (VIO) and the other is the Source-Routed VIO
(SRVIO). The VIO installs a route on each hop along a P-Route (in a (SRVIO). The VIO installs a route on each hop along a Projected
fashion analogous to RPL Storing Mode) whereas the SRVIO installs a Route (in a fashion analogous to RPL Storing Mode) whereas the SRVIO
source-routing state at the ingress node, which uses it to insert a installs a source-routing state at the ingress node, which uses that
routing header in a fashion similar to Non-Storing Mode. state to insert a routing header in a fashion similar to Non-Storing
Mode. Like the TIO, the RPOs MUST be preceded by one or more RTOs to
which they apply, and they can be factorized: multiple contiguous
RPOs indicate alternate paths to the Target(s), more in Section 5.3.
Like the TIO, the RPOs MUST be preceded by one or more RPL Target This specification also introduces a new CMO to enable a RPL Router
Options to which they apply, and they can be factorized: multiple to indicate its siblings to the Root, more in Figure 4.
contiguous RPOs indicate alternate paths to the target(s).
3.1. RPL Instances 4. Identifying a Path
It must be noted that RPL has a concept of instance but does not have It must be noted that RPL has a concept of Instance to represent
a concept of an administrative distance, which exists in certain different routing topologies but does not have a concept of an
proprietary implementations to sort out conflicts between multiple administrative distance, which exists in certain proprietary
sources of routing information. This draft conforms the instance implementations to sort out conflicts between multiple sources of
model as follows: routing information within one routing topology. This draft conforms
the Instance model as follows:
o If the PCE needs to influence a particular instance to add better * If the PCE needs to influence a particular Instance to add better
routes in conformance with the routing objectives in that routes in conformance with the routing objectives in that
instance, it may do so. When the PCE modifies an existing Instance, it may do so as long as it does not create a loop. A
instance then the added routes must not create a loop in that Projected Route is always preferred over a route that is learned
instance. This is achieved by always preferring a route obtained via RPL. This specification uses the RPL Root as a proxy to the
from the PCE over a route that is learned via RPL. PCE. If the actual PCE is a separate entity, then a protocol that
is out of scope for this specification is needed to relay the
control elements between the RPL Root and the PCE.
o If the PCE installs a more specific (say, Traffic Engineered) * A PCE that installs a more specific (say, Traffic Engineered) and
route between a particular pair of nodes then it SHOULD use a possibly complex path (aka a Track) towards a particular Target
Local Instance from the ingress node of that path. A packet MUST use a Local RPL Instance (see section 5 of [RFC6550])
associated with that instance will be routed along that path and associated to that Target to identify the path. We refer to that
MUST NOT be placed over a Global Instance again. A packet that is Local RPLInstanceID as TrackID. A projected path is uniquely
placed on a Global Instance may be injected in the Local Instance identified within the RPL domain by the tuple (Target address,
based on node policy and the Local Instance paramenters. TrackID). When packet is placed on a Track, a RPL Packet
Information (RPI) is added with the TrackID as RPLInstanceID. The
RPLInstanceID has the 'D' flag set, indicating that the
destination address in the IPv6 header is the Target that is used
to identify the Track.
In all cases, the path is indicated by a new Via Information option, * A packet that is routed over a projected path MUST NOT be placed
and the flow is similar to the flow used to obtain loose source over a different RPL Instance again. A packet that is placed on a
routing. Global Instance MAY be injected in a Local Instance based on a
network policy and the Local Instance configuration.
3.2. New RPL Control Message Options A Projected Route is a serial path that may the whole path or a
segment in a complex Track, in which case multiple Projected Routes
are installed with the stuple (Target address, TrackID), and a node
that is present on more than one segment in a Track may be able to
use either of the Projected Routes to forward towards the Target.
The selection of the best route in a Track at forwarding time is out
of scope for this document. [RAW-PS] elaborates on that particular
problem.
5. New RPL Control Messages and Options
5.1. New P-DAO Request Control Message
The PDR is sent to the Root to request a new Path. Exactly one
Target Options MUST be present.
The format of P-DAO Request (PDR) Base Object is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RPLInstanceID |K|R| Flags | PDRLifetime | PDRSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)...
+-+-+-+-+-+-+-+-+
Figure 1: New P-DAO Request Format
TrackID: 8-bit field indicating the topology Instance associated
with 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
either renew it of destroy it.
K: The 'K' flag is set to indicate that the recipient is expected to
send a PDR-ACK back.
R: The 'R' flag is set to indicate that the Requested path should be
redundant.
PDRLifetime: 8-bit unsigned integer. The requested lifetime for the
Track expressed in Lifetime Units (obtained from the Configuration
option). A PDR with a fresher PDRSequence refreshes the lifetime,
and a PDRLifetime of 0 indicates that the track should be
destroyed.
PDRSequence: 8-bit wrapping sequence number. The PDRSequence obeys
the operation in section 7.2 of [RFC6550]. It is incremented at
each PDR message and echoed in the PDR-ACK by the Root. The
PDRSequence is used to correlate a PDR-ACK message with the PDR
message that triggeted it.
5.2. New PDR-ACK Control Message
The new PDR-ACK is sent as a response to a PDR message with the 'K'
flag set. Its format is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TrackID | PDR-ACK Status| Flags | Track Lifetime|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PDRSequence | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)...
+-+-+-+-+-+-+-+
Figure 2: New PDR-ACK Control Message Format
TrackID: The RPLInstanceID of the Track that was created. Set to 0
when no Track is created.
PDR-ACK Status: Indicates the completion. A value up to 127 means
acceptance Values of 128 and above are used for rejection codes;
Track Lifetime: Indicates that remaining Lifetime for the Track, 0
if the Track was destroyed or not created.
PDRSequence: 8-bit wrapping sequence number. It is incremented at
each PDR message and echoed in the PDR-ACK.
5.3. Route Projection Options
The RPOs indicate a series of IPv6 addresses that can be compressed
using the method defined in the "6LoWPAN Routing Header" [RFC8138]
specification using the address of the Root found in the DODAGID
field of DIO messages as Compression Reference.
An RPO indicates a Projected Route that can be a serial Track in full
or a segment of a more complex Track. The Track is identified by a
RPLInstanceID that is either Global or local to the Target of the
Track.
The format of RPOs is as follows: The format of RPOs is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Option Length | Path Sequence | Path Lifetime | | Type | Option Length |Comp.| Flags | TrackID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Lifetime | Path Sequence | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Via Address 1 . . Via Address 1 .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
skipping to change at page 6, line 31 skipping to change at page 9, line 40
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Via Address n . . Via Address n .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Via Information option format Figure 3: Via Information option format
Option Type: 0x0A for VIO, 0x0B for SRVIO (to be confirmed by IANA) Option Type: 0x0A for VIO, 0x0B for SRVIO (to be confirmed by IANA)
Option Length: In bytes; variable, depending on the number of Via Option Length: In bytes; variable, depending on the number of Via
Addresses. Addresses.
Path Sequence: 8-bit unsigned integer. When a RPL Target option is Compression Type: 16-bit unsigned integer. This is the SRH-6LoRH
issued by the root of the DODAG (i.e. in a DAO message), that Type as defined in figure 7 in section 5.1 of [RFC8138] that
root sets the Path Sequence and increments the Path Sequence corresponds to the compression used for all the Via Addresses.
each time it issues a RPL Target option with updated
information. The indicated sequence deprecates any state for a TrackID: 8-bit field indicating the topology Instance associated
given Target that was learned from a previous sequence and adds with the Track.
to any state that was learned for that sequence.
Path Lifetime: 8-bit unsigned integer. The length of time in Path Lifetime: 8-bit unsigned integer. The length of time in
Lifetime Units (obtained from the Configuration option) that Lifetime Units (obtained from the Configuration option) that the
the prefix is valid for route determination. The period starts prefix is valid for route determination. The period starts when a
when a new Path Sequence is seen. A value of 255 (0xFF) new Path Sequence is seen. A value of 255 (0xFF) represents
represents infinity. A value of zero (0x00) indicates a loss infinity. A value of zero (0x00) indicates a loss of
of reachability. A DAO message that contains a Via Information reachability. A DAO message that contains a Via Information
option with a Path Lifetime of zero for a Target is referred as option with a Path Lifetime of zero for a Target is referred as a
a No-Path (for that Target) in this document. No-Path (for that Target) in this document.
Via Address: 16 bytes. IPv6 Address of the next hop towards the Path Sequence: 8-bit unsigned integer. When a RPL Target option is
destination(s) indicated in the target option that immediately issued by the Root of the DODAG (i.e. in a DAO message), that Root
precede the RPO. Via Addresses are indicated in the order of sets the Path Sequence and increments the Path Sequence each time
the data path from the ingress to the egress nodes. it issues a RPL Target option with updated information. The
indicated sequence deprecates any state for a given Target that
was learned from a previous sequence and adds to any state that
was learned for that sequence.
Via Address: 2 to 16 bytes, a compressed IPv6 Address. A Via
Address indicates the next hop within the path towards the
destination(s) that is indicated in the Target option that
immediately precede the RPO in the DAO message. Via Addresses are
indicated in the order of the path from the ingress to the egress
nodes. All Via addresses are expressed in the same size as
indicated by the Compression Type.
An RPO MUST contain at least one Via Address, and a Via Address MUST An RPO MUST contain at least one Via Address, and a Via Address MUST
NOT be present more than once, otherwise the RPO MUST be ignored. NOT be present more than once, otherwise the RPO MUST be ignored.
3.3. RPI for Projected Routes 5.4. Sibling Information Option
RPL [RFC6550], Section 11.2, specifies the RPL Packet Information The Sibling Information Option (SIO) provides indication on siblings
(RPI) as a set of fields that are placed by RPL routers in IP packets that could be used by the Root to form Projected Routes. The format
to identify the RPL Instance, detect anomalies and trigger corrective of SIOs is as follows:
actions.
In particular, the SenderRank, which is the scalar metric computed by 0 1 2 3
a specialized Objective Function such as described in [RFC6552], 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
indicates the Rank of the sender and is modified at each hop. The +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SenderRank field is used to validate that the packet progresses in | Type | Option Length |Comp.|B| Flags | Opaque |
the expected direction, either upwards or downwards, along the DODAG. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Step of Rank | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
. .
. Sibling Address .
. .
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RPL defines the "RPL Option for Carrying RPL Information in Data- Figure 4: Sibling Information Option Format
Plane Datagrams" [RFC6553] to transport the RPI, which is carried in
an IPv6 Hop-by-Hop Options Header [RFC8200], typically consuming
eight bytes per packet.
This specification updates [RFC6550] as follows. When using Option Type: 0x0C (to be confirmed by IANA)
projected routes, the Rank is useless and SHOULD be set to 0 in the
non-compressed form, and can be elided in the compressed form (see
Section 4.1). In a same fashion, the O, R, and F flags that are
defined in Section 11.2 of [RFC6550] are not used for packets that
follow a projected route and they MUST be reset. A new flag is
added, the P flag that indicates that the packet is injected along a
projected route.
3.4. Projected DAO Option Length: In bytes; variable, depending on the number of Via
Addresses.
This draft adds a capability to RPL whereby the root of a DODAG Compression Type: 16-bit unsigned integer. This is the SRH-6LoRH
Type as defined in figure 7 in section 5.1 of [RFC8138] that
corresponds to the compression used for the Sibling Address.
B: 1-bit flag that is set to indicate that the connectivity to the
sibling is bidirectional and roughly symmetrical. In that case,
only one of the siblings may report the SIO for the hop. If 'B'
is not set then the SIO only indicates connectivity from the
sibling to this node, and does not provide information on the hop
from this node to the sibling.
Opaque: MAY be used to carry information that the node and the Root
understand, e.g., a particular representation of the Link
properties such as a proprietary Link Quality Information for
packets received from the sibling. An industraial Alliance that
uses RPL for a particular use / environment MAY redefine the use
of this field to fit its needs.
Step of Rank: 16-bit unsigned integer. This is the Step of Rank
[RFC6550] as computed by the Objective Function between this node
and the sibling.
Reserved: MUST be set to zero by the sender and MUST be ignored by
the receiver.
Sibling Address: 2 to 16 bytes, a compressed IPv6 Address. a Via
Address indicates the next hop towards the destination(s) that is
indicated in the Target option that immediately precede the RPO in
the DAO message. Via Addresses are indicated in the order of the
data path from the ingress to the egress nodes. All Via addresses
are expressed in the same size as indicated by the Compression
Type
An SIO MAY be immediately followed by a DAG Metric Container. In
that case the DAG Metric Container provides additional metrics for
the hop from the Sibling to this node.
6. Projected DAO
This draft adds a capability to RPL whereby the Root of a DODAG
projects a route by sending an extended DAO message called a projects a route by sending an extended DAO message called a
Projected-DAO (P-DAO) to an arbitrary router in the DODAG, indicating Projected-DAO (P-DAO) to an arbitrary router in the DODAG, indicating
one or more sequence(s) of routers inside the DODAG via which the one or more sequence(s) of routers inside the DODAG via which the
target(s) indicated in the Target Information Option(s) (TIO) can be Target(s) indicated in the RPL Target Option(s) (RTO) can be reached.
reached.
A P-DAO is sent from a global address of the root to a global address A P-DAO is sent from a global address of the Root to a global address
of the recipient, and MUST be confirmed by a DAO-ACK, which is sent of the recipient, and MUST be confirmed by a DAO-ACK, which is sent
back to a global address of the root. back to a global address of the Root.
A P-DAO message MUST contain at least one TIO and at least one RPO A P-DAO message MUST contain at least one RTO and at least one RPO
following it. There can be at most one such sequence of TIOs and following it. There can be at most one such sequence of RTOs and
then RPOs. then RPOs.
Like a classical DAO message, a P-DAO is processed only if it is Like a classical DAO message, a P-DAO is processed only if it is
"new" per section 9.2.2. "Generation of DAO Messages" of the RPL "new" per section 9.2.2. "Generation of DAO Messages" of the RPL
specification [RFC6550]; this is determined using the Path Sequence specification [RFC6550]; this is determined using the Path Sequence
information from the RPO as opposed to a TIO. Also, a Path Lifetime information from the RPO as opposed to a TIO. Also, a Path Lifetime
of 0 in an RPO indicates that a route is to be removed. of 0 in an RPO indicates that a route is to be removed.
There are two kinds of operation for the P-Routes, the Storing Mode There are two kinds of operation for the Projected Routes, the
and the Non-Storing Mode. Storing Mode and the Non-Storing Mode.
o The Non-Storing Mode is discussed in Section 3.4.1. It uses an * The Non-Storing Mode is discussed in Section 6.1. It uses an
SRVIO that carries a list of Via Addresses to be used as a source- SRVIO that carries a list of Via Addresses to be used as a source-
routed path to the target. The recipient of the P-DAO is the routed path to the Target. The recipient of the P-DAO is the
ingress router of the source-routed path. Upon a Non-Storing Mode ingress router of the source-routed path. Upon a Non-Storing Mode
P-DAO, the ingress router installs a source-routed state to the P-DAO, the ingress router installs a source-routed state to the
target and replies to the root directly with a DAO-ACK message. Target and replies to the Root directly with a DAO-ACK message.
o The Storing Mode is discussed in Section 3.4.2. It uses a VIO * The Storing Mode is discussed in Section 6.2. It uses a VIO with
with one Via Address per consecutive hop, from the ingress to the one Via Address per consecutive hop, from the ingress to the
egress of the path, including the list of all intermediate routers egress of the path, including the list of all intermediate routers
in the data path order. The Via Addresses indicate the routers in in the data path order. The Via Addresses indicate the routers in
which the routing state to the target have to be installed via the which the routing state to the Target have to be installed via the
next Via Address in the VIO. In normal operations, the P-DAO is next Via Address in the VIO. In normal operations, the P-DAO is
propagated along the chain of Via Routers from the egress router propagated along the chain of Via Routers from the egress router
of the path till the ingress one, which confirms the installation of the path till the ingress one, which confirms the installation
to the root with a DAO-ACK message. Note that the root may be the to the Root with a DAO-ACK message. Note that the Root may be the
ingress and it may be the egress of the path, that it can also be ingress and it may be the egress of the path, that it can also be
neither but it cannot be both. neither but it cannot be both.
In case of a forwarding error along a P-Route, an ICMP error is sent In case of a forwarding error along a Projected Route, an ICMP error
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 7.3). The root can then modify or remove the P-Route. The Section 8.2). The Root can then modify or remove the Projected
"Error in Projected Route" message has the same format as the Route. The "Error in Projected Route" message has the same format as
"Destination Unreachable Message", as specified in RFC 4443 the "Destination Unreachable Message", as specified in RFC 4443
[RFC4443]. The portion of the invoking packet that is sent back in [RFC4443]. The portion of the invoking packet that is sent back in
the ICMP message SHOULD record at least up to the routing header if the ICMP message SHOULD record at least up to the routing header if
one is present, and the routing header SHOULD be consumed by this one is present, and the routing header SHOULD be consumed by this
node so that the destination in the IPv6 header is the next hop that node so that the destination in the IPv6 header is the next hop that
this node could not reach. if a 6LoWPAN Routing Header (6LoRH) this node could not reach. if a 6LoWPAN Routing Header (6LoRH)
[RFC8138] is used to carry the IPv6 routing information in the outter [RFC8138] is used to carry the IPv6 routing information in the outter
header then that whole 6LoRH information SHOULD be present in the header then that whole 6LoRH information SHOULD be present in the
ICMP message. The sender and exact operation depend on the Mode and ICMP message. The sender and exact operation depend on the Mode and
is described in Section 3.4.1 and Section 3.4.2 respectively. is described in Section 6.1 and Section 6.2 respectively.
3.4.1. Non-Storing Mode P-Route 6.1. Non-Storing Mode Projected Route
As illustrated in Figure 2, a P-DAO that carries an SRVIO enables the As illustrated in Figure 5, a P-DAO that carries an SRVIO enables the
root to install a source-routed path towards a target in any Root to install a source-routed path towards a Target in any
particular router; with this path information the router can add a particular router; with this path information the router can add a
source routed header reflecting the P-route to any packet for which source routed header reflecting the Projected Route to any packet for
the current destination either is the said target or can be reached which the current destination either is the said Target or can be
via the target. reached via the Target.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ | P ^ | +-----+ | P ^ |
| | DAO | ACK | Loose | | DAO | ACK | Loose
o o o o router V | | Source o o o o router V | | Source
o o o o o o o o o | P-DAO . Route o o o o o o o o o | P-DAO . Route
o o o o o o o o o o | Source . Path o o o o o o o o o o | Source . Path
o o o o o o o o o | Route . From o o o o o o o o o | Route . From
o o o o o o o o | Path . Root o o o o o o o o | Path . Root
o o o o o target V . To o o o o o Target V . To
o o o o | Desti- o o o o | Desti-
o o o o | nation o o o o | nation
destination V destination V
LLN LLN
Figure 2: Projecting a Non-Storing Route Figure 5: Projecting a Non-Storing Route
A route indicated by an SRVIO may be loose, meaning that the node A route indicated by an SRVIO may be loose, meaning that the node
that owns the next listed Via Address is not necessarily a neighbor. that owns the next listed Via Address is not necessarily a neighbor.
Without proper loop avoidance mechanisms, the interaction of loose Without proper loop avoidance mechanisms, the interaction of loose
source routing and other mechanisms may effectively cause loops. In source routing and other mechanisms may effectively cause loops. In
order to avoid those loops, if the router that installs a P-route order to avoid those loops, if the router that installs a Projected
does not have a connected route (a direct adjacency) to the next Route does not have a connected route (a direct adjacency) to the
soure routed hop and fails to locate it as a neighbor or a neighbor next soure routed hop and fails to locate it as a neighbor or a
of a neighbor, then it MUST ensure that it has another P-Route to the neighbor of a neighbor, then it MUST ensure that it has another
next loose hop under the control of the same route computation Projected Route to the next loose hop under the control of the same
system, otherwise the P-DAO is rejected. route computation system, otherwise the P-DAO is rejected.
When forwarding a packet to a destination for which the router When forwarding a packet to a destination for which the router
determines that routing happens via the target, the router inserts determines that routing happens via the Target, the router inserts
the source routing header in the packet to reach the target. In the the source routing header in the packet to reach the Target. In the
case of a loose source-routed path, there MUST be either a neighbor 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 packet s that is adjacent to the loose next hop, on which case the packet s
forwarded to that neighbor, or a source-routed path to the loose next forwarded to that neighbor, or a source-routed path to the loose next
hop; in the latter case, another encapsulation takes place and the hop; in the latter case, another encapsulation takes place and the
process possibly recurses; otherwise the packet is dropped. process possibly recurses; otherwise the packet is dropped.
In order to add a source-routing header, the router encapsulates the In order to add a source-routing header, the router encapsulates the
packet with an IP-in-IP header and a non-storing mode source routing packet with an IP-in-IP header and a non-storing mode source routing
header (SRH) [RFC6554]. In the uncompressed form the source of the header (SRH) [RFC6554]. In the uncompressed form the source of the
packet would be self, the destination would be the first Via Address packet would be self, the destination would be the first Via Address
in the SRVIO, and the SRH would contain the list of the remaining Via in the SRVIO, and the SRH would contain the list of the remaining Via
Addresses and then the target. Addresses and then the Target.
In practice, the router will normally use the "IPv6 over Low-Power In practice, the router will normally use the "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch" [RFC8025] Wireless Personal Area Network (6LoWPAN) Paging Dispatch" [RFC8025]
to compress the RPL artifacts as indicated in the "6LoWPAN Routing to compress the RPL artifacts as indicated in [RFC8138]. In that
Header" [RFC8138] specification. In that case, the router indicates case, the router indicates self as encapsulator in an IP-in-IP 6LoRH
self as encapsulator in an IP-in-IP 6LoRH Header, and places the list Header, and places the list of Via Addresses in the order of the VIO
of Via Addresses in the order of the VIO and then the target in the and then the Target in the SRH 6LoRH Header.
SRH 6LoRH Header.
+-+ ... -+-+ ... +-+- ... -+-+- ... -+-+-+- ... -+-+ ...
|11110001|SRH-6LoRH| ERPI- | IP-in-IP Encap | NH=1 |11110CPP|
|Page 1 |Type1 S=2| 6LoRH | 6LoRH sulator |LOWPAN_IPHC| UDP |
+-+ ... -+-+ ... +-+- ... -+-+- ... -+-+-+- ... -+-+ ...
<-RFC8138-><-This-><----RFC 8138----><-----RFC 6282------->
RFC 5 to 19 bytes No RPL artifact
Figure 3: Example Compressed Packet with SRH.
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 [RFC6550]. Upon this message, the in section 11.2.2.3. of [RFC6550]. Upon this message, the
encapsulating node SHOULD stop using the source route path for a encapsulating node SHOULD stop using the source route path for a
period of time and it SHOULD send an ICMP message with a Code "Error period of time and it SHOULD send an ICMP message with a Code "Error
in Projected Route" to the root. Failure to follow these steps may in Projected Route" to the Root. Failure to follow these steps may
result in packet loss and wasted resources along the source route result in packet loss and wasted resources along the source route
path that is broken. path that is broken.
3.4.2. Storing-Mode P-Route 6.2. Storing-Mode Projected Route
As illustrated in Figure 4, the Storing Mode projected iq used by the As illustrated in Figure 6, the Storing Mode route projection is used
root to install a routing state towards a target in the routers along by the Root to install a routing state towards a Target in the
a segment between an ingress and an egress router; this enables the routers along a segment between an ingress and an egress router; this
routers to forward along that segment any packet for which the next enables the routers to forward along that segment any packet for
loose hop is the said target, for instance a loose source routed which the next loose hop is the said Target, for Instance a loose
packet for which the next loose hop is the target, or a packet for source routed packet for which the next loose hop is the Target, or a
which the router has a routing state to the final destination via the packet for which the router has a routing state to the final
target. destination via the Target.
------+--------- ------+---------
| 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 4: Projecting a route Figure 6: Projecting a route
In order to install the relevant routing state along the segment In order to install the relevant routing state along the segment
between an ingress and an egress routers, the root sends a unicast between an ingress and an egress routers, the Root sends a unicast
P-DAO message to the egress router of the routing segment that must P-DAO message to the egress router of the routing segment that must
be installed. The P-DAO message contains the ordered list of hops be installed. The P-DAO message contains the ordered list of hops
along the segment as a direct sequence of Via Information options along the segment as a direct sequence of Via Information options
that are preceded by one or more RPL Target options to which they that are preceded by one or more RPL Target options to which they
relate. Each Via Information option contains a Path Lifetime for relate. Each Via Information option contains a Path Lifetime for
which the state is to be maintained. which the state is to be maintained.
The root sends the P-DAO directly to the egress node of the segment. The Root sends the P-DAO directly to the egress node of the segment.
In that P-DAO, the destination IP address matches the Via Address in In that P-DAO, the destination IP address matches the Via Address in
the last VIO. This is how the egress recognizes its role. In a the last VIO. This is how the egress recognizes its role. In a
similar fashion, the ingress node recognizes its role as it matches similar fashion, the ingress node recognizes its role as it matches
Via Address in the first VIO. Via Address in the first VIO.
The egress node of the segment is the only node in the path that does The egress node of the segment is the only node in the path that does
not install a route in response to the P-DAO; it is expected to be not install a route in response to the P-DAO; it is expected to be
already able to route to the target(s) on its own. It may either be already able to route to the Target(s) on its own. It may either be
the target, or may have some existing information to reach the the Target, or may have some existing information to reach the
target(s), such as a connected route or an already installed P-Route. Target(s), such as a connected route or an already installed
If one of the targets cannot be located, the node MUST answer to the Projected Route. If one of the Targets cannot be located, the node
root with a negative DAO-ACK listing the target(s) that could not be MUST answer to the Root with a negative DAO-ACK listing the Target(s)
located (suggested status 10 to be confirmed by IANA). that could not be located (suggested status 10 to be confirmed by
IANA).
If the egress node can reach all the targets, then it forwards the If the egress node can reach all the Targets, then it forwards the
P-DAO with unchanged content to its loose predecessor in the segment P-DAO with unchanged content to its loose predecessor in the segment
as indicated in the list of Via Information options, and recursively as indicated in the list of Via Information options, and recursively
the message is propagated unchanged along the sequence of routers the message is propagated unchanged along the sequence of routers
indicated in the P-DAO, but in the reverse order, from egress to indicated in the P-DAO, but in the reverse order, from egress to
ingress. ingress.
The address of the predecessor to be used as destination of the The address of the predecessor to be used as destination of the
propagated DAO message is found in the Via Information option the propagated DAO message is found in the Via Information option the
precedes the one that contain the address of the propagating node, precedes the one that contain the address of the propagating node,
which is used as source of the packet. which is used as source of the packet.
Upon receiving a propagated DAO, an intermediate router as well as Upon receiving a propagated DAO, an intermediate router as well as
the ingress router install a route towards the DAO target(s) via its the ingress router install a route towards the DAO Target(s) via its
successor in the P-DAO; the router locates the VIO that contains its successor in the P-DAO; the router locates the VIO that contains its
address, and uses as next hop the address found in the Via Address address, and uses as next hop the address found in the Via Address
field in the following VIO. The router MAY install additional routes field in the following VIO. The router MAY install additional routes
towards the addresses that are located in VIOs that are after the towards the addresses that are located in VIOs that are after the
next one, if any, but in case of a conflict or a lack of resource, a next one, if any, but in case of a conflict or a lack of resource, a
route to a target installed by the root has precedence. route to a Target installed by the Root has precedence.
The process recurses till the P-DAO is propagated to ingress router The process recurses till the P-DAO is propagated to ingress router
of the segment, which answers with a DAO-ACK to the root. of the segment, which answers with a DAO-ACK to the Root.
Also, the path indicated in a P-DAO may be loose, in which case the Also, the path indicated in a P-DAO may be loose, in which case the
reachability to the next hop has to be asserted. Each router along reachability to the next hop has to be asserted. Each router along
the path indicated in a P-DAO is expected to be able to reach its the path indicated in a P-DAO is expected to be able to reach its
successor, either with a connected route (direct neighbor), or by successor, either with a connected route (direct neighbor), or by
routing, for instance following a route installed previously by a DAO routing, for Instance following a route installed previously by a DAO
or a P-DAO message. If that route is not connected then a recursive or a P-DAO message. If that route is not connected then a recursive
lookup may take place at packet forwarding time to find the next hop lookup may take place at packet forwarding time to find the next hop
to reach the target(s). If it does not and cannot reach the next to reach the Target(s). If it does not and cannot reach the next
router in the P-DAO, the router MUST answer to the root with a router in the P-DAO, the router MUST answer to the Root with a
negative DAO-ACK indicating the successor that is unreachable negative DAO-ACK indicating the successor that is unreachable
(suggested status 11 to be confirmed by IANA). (suggested status 11 to be confirmed by IANA).
A Path Lifetime of 0 in a Via Information option is used to clean up A Path 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 is 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 interpreted as a No-Path DAO and results in cleaning up existing
state as opposed to refreshing an existing one or installing a new state as opposed to refreshing an existing one or installing a new
one. one.
In case of a forwarding error along a Storing Mode P-Route, the node In case of a forwarding error along a Storing Mode Projected Route,
that fails to forward SHOULD send an ICMP error with a code "Error in the node that fails to forward SHOULD send an ICMP error with a code
Projected Route" to the root. Failure to do so may result in packet "Error in Projected Route" to the Root. Failure to do so may result
loss and wasted resources along the P-Route that is broken. in packet loss and wasted resources along the Projected Route that is
broken.
4. Extending RFC 8138
4.1. Elective RPI 6LoRH
[RFC8138] defines a Critical 6LoRH to compress the RPL RPI found in
normal packets inside a RPL domain, the RPI-6LoRH.
this specification introduces the ERPI-6LoRH header that MUST be used
to compress the RPI in packets that follow a projected route. As
discussed in Section 3.3, the Rank and the O, R, anf F flags are
always set to 0 and can be elided. The new P flag is always set and
can also be elided. It results that in general only the RPL
InstanceID is necessary in the compressed form.
This specification adds an optimization whereby the local
RPLInstanceID 0 for the source of the packet (the encapsulator when
using IP in IP) can be elided. This is the case where the
RPLInstanceID is encoded as binary b10000000, decimal 128, in the
non-compressed form.
The ERPI-6LoRH header is Elective since it does not contain
information that is critical to the routing and it can be ignored
when not understood. The resulting format is illustrated in Figure 5
below:
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|1| Length | 6LoRH Type 5 | RPLInstanceID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: A ERPI-6LoRH carrying a RPLInstanceID
The ERPI-6LoRH header is identifies by a 6LoRH Type of 5 (to be
confirmed by IANA), which is the same value as the RPI-6LoRH but in
the Elective namespace.If the RPLInstanceID is a local RPLInstanceID
0 for the source of the packet then it MUST be elided and the length
MUST be set to 0. Else the length MUST be set to 1 to indicate that
the ERPI-6LoRH carries a RPLinstanceID.
5. Extending RFC 6553
5.1. Uncompressed RPL Option
[RFC6553] defines a format for the RPI that is suitable for
transporting in the IPv6 Hop-by-Hop Header [RFC8200]. This
specification introduces a new flag in the RPI that must be encoded
in any format includeing uncompressed.
The updated format for the RPL Option is presented in Figure 6.
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 6: RPL Option
New fields:
P: 1-bit flag; indicates that the packet is routed along
a projected route.
6. Security Considerations 7. Security Considerations
This draft uses messages that are already present in RPL [RFC6550] This draft uses messages that are already present in RPL [RFC6550]
with optional secured versions. The same secured versions may be with optional secured versions. The same secured versions may be
used with this draft, and whatever security is deployed for a given used 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 8. IANA Considerations
7.1. New Elective 6LoWPAN Routing Header Type
This specification assigns a new value (to be confirmed by IANA) in
the Elective 6LoWPAN Routing Header Type Registry created for RFC
8138 as below:
+---------------+-------------+----------------+
| Value | Meaning | Defining Spec |
+---------------+-------------+----------------+
| 5 (suggested) | ERPI-6LoRH | This document |
+---------------+-------------+----------------+
Table 1: New Elective 6LoWPAN Routing Header Type
7.2. New RPL Control Codes 8.1. New RPL Control Codes
This document extends the IANA registry created by RFC 6550 for RPL This document extends the IANA registry created by RFC 6550 for RPL
Control Codes as follows: Control Codes as follows:
+------+-------------------+---------------+ +------+--------------------------------------+---------------+
| Code | Description | Reference | | Code | Description | Reference |
+------+-------------------+---------------+ +======+======================================+===============+
| 0x0A | Via | This document | | 0x0A | Via Information option | This document |
| | | | +------+--------------------------------------+---------------+
| 0x0B | Source-Routed Via | This document | | 0x0B | Source-Routed Via Information option | This document |
+------+-------------------+---------------+ +------+--------------------------------------+---------------+
RPL Control Codes Table 1: RPL Control Codes
This document is updating the registry created by RFC 6550 for the This document is updating the registry created by RFC 6550 for the
RPL 3-bit Mode of Operation (MOP) as follows: RPL 3-bit Mode of Operation (MOP) as follows:
+-----------+----------------------------------------+--------------+ +-----------+-------------------------------+-----------+
| MOP value | Description | Reference | | MOP value | Description | Reference |
+-----------+----------------------------------------+--------------+ +===========+===============================+===========+
| 5 | Non-Storing mode of operation with | This | | 5 | Non-Storing mode of operation | This |
| | P-Routes | document | | | with Projected Routes | document |
| | | | +-----------+-------------------------------+-----------+
| 6 | Storing mode of operation with | This | | 6 | Storing mode of operation | This |
| | P-Routes | document | | | with Projected Routes | document |
+-----------+----------------------------------------+--------------+ +-----------+-------------------------------+-----------+
DIO Mode of operation Table 2: DIO Mode of operation
7.3. Error in Projected Route ICMPv6 Code 8.2. 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 P-Route. This ICMPv6 error message is cannot be forwarded along a Projected Route. This ICMPv6 error
"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 9. Acknowledgments
The authors wish to acknowledge JP Vasseur and Patrick Wetterwald for
their contributions to the ideas developed here.
9. References The authors wish to acknowledge JP Vasseur, James Pylakutty and
Patrick Wetterwald for their contributions to the ideas developed
here.
9.1. Normative References 10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89, Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006, RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>. <https://www.rfc-editor.org/info/rfc4443>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing
Protocol for Low-Power and Lossy Networks (RPL)",
RFC 6552, DOI 10.17487/RFC6552, March 2012,
<https://www.rfc-editor.org/info/rfc6552>.
[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>.
[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch", Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016, RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>. <https://www.rfc-editor.org/info/rfc8025>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network "IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>. April 2017, <https://www.rfc-editor.org/info/rfc8138>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 11. Informative References
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
9.2. Informative References
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-20 (work
in progress), March 2019.
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-13 (work in progress), May 2019.
[PCE] IETF, "Path Computation Element", [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
<https://datatracker.ietf.org/doc/charter-ietf-pce/>. Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
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>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [6TiSCH-ARCHI]
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Thubert, P., "An Architecture for IPv6 over the TSCH mode
2014, <https://www.rfc-editor.org/info/rfc7102>. of IEEE 802.15.4", Work in Progress, Internet-Draft,
draft-ietf-6tisch-architecture-27, 18 October 2019,
<https://tools.ietf.org/html/draft-ietf-6tisch-
architecture-27>.
[RAW-PS] Thubert, P. and G. Papadopoulos, "Reliable and Available
Wireless Problem Statement", Work in Progress, Internet-
Draft, draft-pthubert-raw-problem-statement-04, 23 October
2019, <https://tools.ietf.org/html/draft-pthubert-raw-
problem-statement-04>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
[PCE] IETF, "Path Computation Element", November 2019,
<https://datatracker.ietf.org/doc/charter-ietf-pce/>.
Appendix A. Applications Appendix A. Applications
A.1. Loose Source Routing in Non-storing Mode A.1. Loose Source Routing in Non-storing Mode
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 7. uses the Non-Storing Mode of Operation as represented in Figure 7.
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
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ ^ | | +-----+ ^ | |
skipping to change at page 18, line 36 skipping to change at page 21, line 8
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 7: RPL non-storing mode of operation Figure 7: 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.
It results that the root, or then some associated centralized It results that the Root, or then some associated centralized
computation engine such as a PCE, can determine the amount of packets computation engine such as a PCE, can determine the amount of packets
that reach a destination in the RPL domain, and thus the amount of that reach a destination in the RPL domain, and thus the amount of
energy and bandwidth that is wasted for transmission, between itself energy and bandwidth that is wasted for transmission, between itself
and the destination, as well as the risk of fragmentation, any and the destination, as well as the risk of fragmentation, any
potential delays because of a paths longer than necessary (shorter potential delays because of a paths longer than necessary (shorter
paths exist that would not traverse the root). paths exist that would not traverse the Root).
As a network gets deep, the size of the source routing header that As a network gets deep, the size of the source routing header that
the root must add to all the downward packets becomes an issue for the Root must add to all the downward packets becomes an issue for
nodes that are many hops away. In some use cases, a RPL network nodes that are many hops away. In some use cases, a RPL network
forms long lines and a limited amount of well-targeted routing state forms long lines and a limited amount of well-Targeted routing state
would allow to make the source routing operation loose as opposed to would allow to make the source routing operation loose as opposed to
strict, and save packet size. Limiting the packet size is directly strict, and save packet size. Limiting the packet size is directly
beneficial to the energy budget, but, mostly, it reduces the chances beneficial to the energy budget, but, mostly, it reduces the chances
of frame loss and/or packet fragmentation, which is highly of frame loss and/or packet fragmentation, which is highly
detrimental to the LLN operation. Because the capability to store a detrimental to the LLN operation. Because the capability to store a
routing state in every node is limited, the decision of which route routing state in every node is limited, the decision of which route
is installed where can only be optimized with a global knowledge of is installed where can only be optimized with a global knowledge of
the system, a knowledge that the root or an associated PCE may the system, a knowledge that the Root or an associated PCE may
possess by means that are outside of the scope of this specification. possess by means that are outside of the scope of this specification.
This specification enables to store source-routed or storing mode This specification enables to store source-routed or storing mode
state in intermediate routers, which enables to limit the excursion state in intermediate routers, which enables to limit the excursion
of the source route headers in deep networks. Once a P-DAO exchange of the source route headers in deep networks. Once a P-DAO exchange
has taken place for a given target, if the root operates in non has taken place for a given Target, if the Root operates in non
storing mode, then it may elide the sequence of routers that is storing mode, then it may elide the sequence of routers that is
installed in the network from its source route headers to destination installed in the network from its source route headers to destination
that are reachable via that target, and the source route headers that are reachable via that Target, and the source route headers
effectively become loose. effectively become loose.
A.2. Transversal Routes in storing and non-storing modes A.2. Transversal Routes in storing and non-storing modes
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 8: illustrated in Figure 8:
o in non-storing mode, all packets routed within the DODAG flow all * in non-storing mode, all packets routed within the DODAG flow all
the way up to the root of the DODAG. If the destination is in the the way up to the Root of the DODAG. If the destination is in the
same DODAG, the root must encapsulate the packet to place a same DODAG, the Root must encapsulate the packet to place a
Routing Header that has the strict source route information down Routing Header that has the strict source route information down
the DODAG to the destination. This will be the case even if the the DODAG to the destination. This will be the case even if the
destination is relatively close to the source and the root is destination is relatively close to the source and the Root is
relatively far off. relatively far off.
o 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.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
skipping to change at page 21, line 18 skipping to change at page 23, line 42
example of service using this mechanism oculd be a control loop that example of service using this mechanism oculd be a control loop that
would be installed in a network that uses classical RPL for would be installed in a network that uses classical RPL for
asynchronous data collection. In that case, the P2P path may be asynchronous data collection. In that case, the P2P path may be
installed in a different RPL Instance, with a different objective installed in a different RPL Instance, with a different objective
function. function.
Appendix B. Examples Appendix B. Examples
B.1. Using storing mode P-DAO in non-storing mode MOP B.1. Using storing mode P-DAO in non-storing mode MOP
In non-storing mode, the DAG root maintains the knowledge of the In non-storing mode, the DAG Root maintains the knowledge of the
whole DODAG topology, so when both the source and the destination of whole DODAG topology, so when both the source and the destination of
a packet are in the DODAG, the root can determine the common parent a packet are in the DODAG, the Root can determine the common parent
that would have been used in storing mode, and thus the list of nodes that would have been used in storing mode, and thus the list of nodes
in the path between the common parent and the destination. For in the path between the common parent and the destination. For
instance in the diagram shown in Figure 10, if the source is node 41 Instance in the diagram shown in Figure 10, if the source is node 41
and the destination is node 52, then the common parent is node 22. and the destination is node 52, then the common parent is node 22.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
| \ \____ | \ \____
skipping to change at page 21, line 47 skipping to change at page 24, line 26
o 22 o 23 o 24 o 25 o 22 o 23 o 24 o 25
/ \ | \ \ / \ | \ \
o 31 o 32 o o o 35 o 31 o 32 o o o 35
/ / | \ | \ / / | \ | \
o 41 o 42 o o o 45 o 46 o 41 o 42 o o o 45 o 46
| | | | \ | | | | | \ |
o 51 o 52 o 53 o o 55 o 56 o 51 o 52 o 53 o o 55 o 56
LLN LLN
Figure 10: Example DODAG forming a logical tree topology Figure 10: Example DODAG forming a logical tree topology
With this draft, the root can install a storing mode routing states With this draft, the Root can install a storing mode routing states
along a segment that is either from itself to the destination, or along a segment that is either from itself to the destination, or
from one or more common parents for a particular source/destination from one or more common parents for a particular source/destination
pair towards that destination (in this particular example, this would pair towards that destination (in this particular example, this would
be the segment made of nodes 22, 32, 42). be the segment made of nodes 22, 32, 42).
In the example below, say that there is a lot of traffic to nodes 55 In the example below, say that there is a lot of traffic to nodes 55
and 56 and the root decides to reduce the size of routing headers to and 56 and the Root decides to reduce the size of routing headers to
those destinations. The root can first send a DAO to node 45 those destinations. The Root can first send a DAO to node 45
indicating target 55 and a Via segment (35, 45), as well as another indicating Target 55 and a Via segment (35, 45), as well as another
DAO to node 46 indicating target 56 and a Via segment (35, 46). This DAO to node 46 indicating Target 56 and a Via segment (35, 46). This
will save one entry in the routing header on both sides. The root will save one entry in the routing header on both sides. The Root
may then send a DAO to node 35 indicating targets 55 and 56 a Via may then send a DAO to node 35 indicating Targets 55 and 56 a Via
segment (13, 24, 35) to fully optimize that path. segment (13, 24, 35) to fully optimize that path.
Alternatively, the root may send a DAO to node 45 indicating target Alternatively, the Root may send a DAO to node 45 indicating Target
55 and a Via segment (13, 24, 35, 45) and then a DAO to node 46 55 and a Via segment (13, 24, 35, 45) and then a DAO to node 46
indicating target 56 and a Via segment (13, 24, 35, 46), indicating indicating Target 56 and a Via segment (13, 24, 35, 46), indicating
the same DAO Sequence. the same DAO Sequence.
B.2. Projecting a storing-mode transversal route B.2. Projecting a storing-mode transversal route
In this example, say that a PCE determines that a path must be In this example, say that a PCE determines that a path must be
installed between node S and node D via routers A, B and C, in order installed between node S and node D via routers A, B and C, in order
to serve the needs of a particular application. to serve the needs of a particular application.
The root sends a P-DAO with a target option indicating the The Root sends a P-DAO with a Target option indicating the
destination D and a sequence Via Information option, one for S, which destination D and a sequence Via Information option, one for S, which
is the ingress router of the segment, one for A and then for B, which is the ingress router of the segment, one for A and then for B, which
are an intermediate routers, and one for C, which is the egress are an intermediate routers, and one for C, which is the egress
router. router.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
skipping to change at page 22, line 49 skipping to change at page 25, line 27
+-----+ +-----+
| P-DAO message to C | P-DAO message to C
o | o o o | o o
o o o | o o o o o o o o | o o o o o
o o o | o o o o o o o o o | o o o o o o
o o V o o o o o o o o V 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: P-DAO from root Figure 11: P-DAO from Root
Upon reception of the P-DAO, C validates that it can reach D, e.g. Upon reception of the P-DAO, C validates that it can reach D, e.g.
using IPv6 Neighbor Discovery, and if so, propagates the P-DAO using IPv6 Neighbor Discovery, and if so, propagates the P-DAO
unchanged to B. unchanged to B.
B checks that it can reach C and of so, installs a route towards D B checks that it can reach C and of so, installs a route towards D
via C. Then it propagates the P-DAO to A. via C. Then it propagates the P-DAO to A.
The process recurses till the P-DAO reaches S, the ingress of the The process recurses till the P-DAO reaches S, the ingress of the
segment, which installs a route to D via A and sends a DAO-ACK to the segment, which installs a route to D via A and sends a DAO-ACK to the
root. Root.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
^ P-DAO-ACK from S ^ P-DAO-ACK from S
/ 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 12: P-DAO-ACK to root Figure 12: P-DAO-ACK to Root
As a result, a transversal route is installed that does not need to As a result, a transversal route is installed that does not need to
follow the DODAG structure. follow the DODAG structure.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | Border Router | | Border Router
| | (RPL Root) | | (RPL Root)
+-----+ +-----+
| |
o o o o o o o o
o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o
S>>A>>>B>>C>>>D o o o S>>A>>>B>>C>>>D o o o
o o o o o o o o
LLN LLN
Figure 13: Projected Transversal Route Figure 13: Projected Transversal Route
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems Cisco Systems, Inc
Village d'Entreprises Green Side Building D, 45 Allee des Ormes - BP1200
400, Avenue de Roumanille 06254 Mougins - Sophia Antipolis
Batiment T3 France
Biot - Sophia Antipolis 06410
FRANCE
Phone: +33 4 97 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Rahul Arvind Jadhav Rahul Arvind Jadhav
Huawei Tech Huawei Tech
Kundalahalli Village, Whitefield, Kundalahalli Village, Whitefield,
Bangalore, Karnataka 560037 Bangalore 560037
Karnataka
India India
Phone: +91-080-49160700 Phone: +91-080-49160700
Email: rahul.ietf@gmail.com Email: rahul.ietf@gmail.com
Matthew Gillmore Matthew Gillmore
Itron, Inc Itron, Inc
Building D Building D, 2111 N Molter Road
2111 N Molter Road Liberty Lake, 99019
Liberty Lake 99019
United States United States
Phone: +1.800.635.5461 Phone: +1.800.635.5461
Email: matthew.gillmore@itron.com Email: matthew.gillmore@itron.com
James Pylakutty
Cisco Systems
Cessna Business Park
Kadubeesanahalli
Marathalli ORR
Bangalore, Karnataka 560087
INDIA
Phone: +91 80 4426 4140
Email: mundenma@cisco.com
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