draft-ietf-roll-unaware-leaves-02.txt   draft-ietf-roll-unaware-leaves-03.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Updates: 6550, 8505 (if approved) July 4, 2019 Updates: 6550, 8505 (if approved) M. Richardson
Intended status: Standards Track Intended status: Standards Track Sandelman
Expires: January 5, 2020 Expires: March 2, 2020 August 30, 2019
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-02 draft-ietf-roll-unaware-leaves-03
Abstract Abstract
This specification leverages 6LoWPAN ND to provide a unicast and This specification extends RFC6550 and RFC8505 to provide unicast and
multicast routing service in a RPL domain to 6LNs that do not multicast routing services in a RPL domain to 6LNs that are plain
participate to RPL. hosts and do not participate to RPL.
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 January 5, 2020. This Internet-Draft will expire on March 2, 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 13 skipping to change at page 2, line 13
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5
3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 6 3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 6
4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 7 4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 8
5. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 7 5. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 9
6. Dependencies on the 6LN . . . . . . . . . . . . . . . . . . . 8 6. 6LN Requirements to be a RPL-Unware Leaf . . . . . . . . . . 9
7. Protocol Operations for Unicast Addresses . . . . . . . . . . 9 6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 9
7.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 9 6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 10
7.2. 6LN Operation . . . . . . . . . . . . . . . . . . . . . . 11 6.2.1. Support of the HbH Header . . . . . . . . . . . . . . 10
7.3. 6LR Operation . . . . . . . . . . . . . . . . . . . . . . 12 6.2.2. Support of the Routing Header . . . . . . . . . . . . 10
7.4. RPL Root Operation . . . . . . . . . . . . . . . . . . . 13 6.2.3. Support of IPv6 Encapsulation . . . . . . . . . . . . 11
7.5. 6LBR Operation . . . . . . . . . . . . . . . . . . . . . 14 7. Updated RPL Target option . . . . . . . . . . . . . . . . . . 11
8. Protocol Operations for Multicast Addresses . . . . . . . . . 15 8. Protocol Operations for Unicast Addresses . . . . . . . . . . 12
9. Implementation Status . . . . . . . . . . . . . . . . . . . . 17 8.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 12
10. Security Considerations . . . . . . . . . . . . . . . . . . . 17 8.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 12
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 8.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 14
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 8.2. Operation . . . . . . . . . . . . . . . . . . . . . . . . 15
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.2.1. By the 6LN . . . . . . . . . . . . . . . . . . . . . 15
13.1. Normative References . . . . . . . . . . . . . . . . . . 17 8.2.2. By the 6LR . . . . . . . . . . . . . . . . . . . . . 16
13.2. Informative References . . . . . . . . . . . . . . . . . 19 8.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 18
Appendix A. Example Compression . . . . . . . . . . . . . . . . 20 8.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21 9. Protocol Operations for Multicast Addresses . . . . . . . . . 20
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
12.1. RPL Target Option Flags . . . . . . . . . . . . . . . . 22
12.2. New Subsubregistry for the Status values of the RPL DAO-
ACK Message . . . . . . . . . . . . . . . . . . . . . . 22
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
14.1. Normative References . . . . . . . . . . . . . . . . . . 23
14.2. Informative References . . . . . . . . . . . . . . . . . 25
Appendix A. Example Compression . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices and low-power lossy transmissions, duty cycling of the LLN devices and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced the "Routing Protocol for Low Power and Lossy The IETF produced the "Routing Protocol for Low Power and Lossy
Networks" [RFC6550] (RPL) to provide routing services within such Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services
constraints. RPL is a Distance-Vector protocol, which, compared to within such constraints. RPL is a Distance-Vector protocol, which,
link-state protocols, limits the amount of topological knowledge that compared to link-state protocols, limits the amount of topological
needs to be installed and maintained in each node. In order to knowledge that needs to be installed and maintained in each node. In
operate in constrained networks, RPL allows a Routing Stretch (see order to operate in constrained networks, RPL allows a Routing
[RFC6687]), whereby routing is only performed along a DODAG as Stretch (see [RFC6687]), whereby routing is only performed along a
opposed to straight along a shortest path between 2 peers, whatever DODAG as opposed to straight along a shortest path between 2 peers,
that would mean in a given LLN. This trades the quality of peer-to- whatever that would mean in a given LLN. This trades the quality of
peer (P2P) paths for a vastly reduced amount of control traffic and peer-to-peer (P2P) paths for a vastly reduced amount of control
routing state that would be required to operate a any-to-any shortest traffic and routing state that would be required to operate a any-to-
path protocol. Finally, broken routes may be fixed lazily and on- any shortest path protocol. Finally, broken routes may be fixed
demand, based on dataplane inconsistency discovery, which avoids lazily and on-demand, based on dataplane inconsistency discovery,
wasting energy in the proactive repair of unused paths. which avoids wasting energy in the proactive repair of unused paths.
In order to cope with lossy transmissions, RPL forms Direction- In order to cope with lossy transmissions, RPL forms Direction-
Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information
Solicitation (DIS) and DODAG Information Object (DIO) messages. For Solicitation (DIS) and DODAG Information Object (DIO) messages. For
most of the nodes, though not all, a DODAG provides multiple most of the nodes, though not all, a DODAG provides multiple
forwarding solutions towards the Root of the topology via so-called forwarding solutions towards the Root of the topology via so-called
parents. RPL is designed to adapt to fuzzy connectivity, whereby the parents. RPL is designed to adapt to fuzzy connectivity, whereby the
physical topology cannot be expected to reach a stable state, with a physical topology cannot be expected to reach a stable state, with a
lazy control that creates routes proactively but only fixes them when lazy control that creates routes proactively but only fixes them when
they are used by actual traffic. It results that RPL provides they are used by actual traffic. The result is that RPL provides
reachability for most of the LLN nodes, most of the time, but does reachability for most of the LLN nodes, most of the time, but may not
not really converge in the classical sense. RPL provides unicast and really converge in the classical sense. RPL provides unicast and
multicast routing services back to RPL-Aware nodes (RANs). A RAN multicast routing services back to RPL-Aware nodes (RANs). A RAN
will inject routes to self using Destination Advertisement Object will inject routes to itself using Destination Advertisement Object
(DAO) messages sent to either their parents in Storing Mode or to the (DAO) messages sent to either parent-nodes in Storing Mode or to the
Root indicating their parent in Non-Storing Mode. This process Root indicating their parent in Non-Storing Mode. This process
effectively forms a DODAG back to the device that is a subset of the effectively forms a DODAG back to the device that is a subset of the
DODAG to the Root with all links reversed. DODAG to the Root with all links reversed.
When a routing protocol such as RPL is used to maintain reachability When a routing protocol such as RPL is used to maintain reachability
within a Non-Broadcast Multi-Access (NBMA) subnet, some nodes may act within a Non-Broadcast Multi-Access (NBMA) subnet, some nodes may act
as routers and participate to the routing operations whereas others as routers and participate to the routing operations whereas others
may be plain hosts. In RPL terms, a plain host that does not may be plain hosts. In [RFC6550] terms, a host that is reachable
participate to the routing protocol is called a Leaf. It must be over the RPL network is called a Leaf.
noted that a 6LN could participate to RPL and inject DAO routes to
self, but refrain from advertising DIO and get children. In that
case, the 6LN is still a host but not a Leaf.
This specification enables a RPL-Unaware Leaf (RUL) to announce "When to use RFC 6553, 6554 and IPv6-in-IPv6"
itself as a host and demand that the 6LR that accepts the [I-D.ietf-roll-useofrplinfo] introduces the term RPL-Aware-Leaf (RAL)
registration also inject the relevant routing information for the for a leaf that injects routes in RPL to manage the reachability of
Registered Address in the RPL domain on its behalf. The unicast its own IPv6 addresses. In contrast, a RPL-Unaware Leaf (RUL)
packet forwarding operation by the 6LR serving a Leaf 6LN is designates a leaf does not participate to RPL at all. In that case,
described in "When to use RFC 6553, 6554 and IPv6-in-IPv6" the 6LN is a plain host that needs an interface to its RPL router to
[I-D.ietf-roll-useofrplinfo]. This document adds the capability by a obtain routing services over the LLN. This specification enables a
6LR to advertise the Global, Unique-Local and Multicast IPv6 RPL-Unaware Leaf (RUL) to announce itself as a host and request that
address(es) of the 6LN in the RPL protocol. 6LRs that accept the registration also inject the relevant routing
information for the Registered Address in the RPL domain on its
behalf. The unicast packet forwarding operation by the 6LR serving a
Leaf 6LN is described in [I-D.ietf-roll-useofrplinfo].
Examples of routing-agnostic 6LN may include lightly-powered sensors Examples of routing-agnostic 6LN may include lightly-powered sensors
such as window smash sensor (alarm system), or the kinetically such as window smash sensor (alarm system), or the kinetically
powered light switch. Other application of this specification may powered light switch. Other application of this specification may
include a smart grid network that controls appliances - such as include a smart grid network that controls appliances - such as
washing machines or the heating system - in the home. Applicances washing machines or the heating system - in the home. Applicances
may not participate to the RPL protocol operated in the smart grid may not participate to the RPL protocol operated in the smart grid
network but can still receive control packet from the smart grid. network but can still receive control packet from the smart grid.
2. Terminology 2. Terminology
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"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. References 2.2. References
The Terminology used in this document is consistent with and The Terminology used in this document is consistent with and
incorporates that described in Terms Used in Routing for Low-Power incorporates that described in Terms Used in Routing for Low-Power
and Lossy Networks (LLNs). [RFC7102]. and Lossy Networks (LLNs). [RFC7102].
Other terms in use in LLNs are found in Terminology for Constrained-
Node Networks [RFC7228].
A glossary of classical 6LoWPAN acronyms is given in Section 2.3. A glossary of classical 6LoWPAN acronyms is given in Section 2.3.
The term "byte" is used in its now customary sense as a synonym for The term "byte" is used in its now customary sense as a synonym for
"octet". "octet".
"RPL", "RPL Packet Information" (RPI) and "RPL Instance", DIO, DAO "RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by
and DIS messages are defined in the "RPL: IPv6 Routing Protocol for a RPLInstanceID)are defined in "RPL: IPv6 Routing Protocol for Low-
Low-Power and Lossy Networks" [RFC6550] specification. Power and Lossy Networks" [RFC6550] . The DODAG Information
Solicitation (DIS), Destination Advertisement Object (DAO) and DODAG
Information Object (DIO) messages are also specified in [RFC6550].
The Destination Cleanup Object (DCO) message is defined in
[I-D.ietf-roll-efficient-npdao].
This document introduces the term RPL-Unaware Leaf (RUL) to refer to This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware
a node that uses a RPL router (without necessarily knowing it) as 6LR Leaf (RAL) consistently with [I-D.ietf-roll-useofrplinfo]. The term
and depends on that router to obtain reachability for its addresses RPL-Aware Node (RAN) is introduced to refer to a node that is either
inside the RPL domain. On the contrary, the term RPL-Aware Leaf a RAL or a RPL router. As opposed to a RUL, a RAN manages the
(RAL) is used to refer to a host or a router that participates to RPL reachability of its addresses and prefixes by injecting them in RPL
and advertises its addresses of prefixes by itself. by itself.
Other terms in use in LLNs are found in Terminology for Constrained- Other terms in use in LLNs are found in Terminology for Constrained-
Node Networks [RFC7228]. Node Networks [RFC7228].
Readers are expected to be familiar with all the terms and concepts Readers are expected to be familiar with all the terms and concepts
that are discussed in that are discussed in
o "Neighbor Discovery for IP version 6" [RFC4861], o "Neighbor Discovery for IP version 6" [RFC4861],
o "IPv6 Stateless Address Autoconfiguration" [RFC4862], o "IPv6 Stateless Address Autoconfiguration" [RFC4862],
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o "Registration Extensions for IPv6 over Low-Power Wireless Personal o "Registration Extensions for IPv6 over Low-Power Wireless Personal
Area Network (6LoWPAN) Neighbor Discovery" [RFC8505]. Area Network (6LoWPAN) Neighbor Discovery" [RFC8505].
2.3. Glossary 2.3. Glossary
This document often uses the following acronyms: This document often uses the following acronyms:
AR: Address Resolution (aka Address Lookup) AR: Address Resolution (aka Address Lookup)
6BBR: 6LoWPAN Backbone Router (proxy ND) 6LBR: 6LoWPAN Border Router
6LBR: 6LoWPAN Border Router (an Address Registrar that is
authoritative on DAD)
6LN: 6LoWPAN Node (a Low Power host or router) 6LN: 6LoWPAN Node (a Low Power host or router)
6LR: 6LoWPAN Router 6LR: 6LoWPAN Router
6CIO: Capability Indication Option 6CIO: Capability Indication Option
(E)ARO: (Extended) Address Registration Option (E)ARO: (Extended) Address Registration Option
(E)DAR: (Extended) Duplicate Address Request (E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation (E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection DAD: Duplicate Address Detection
DAO: Destination Advertisement Object
DCO: Destination Cleanup Object
DIS: DODAG Information Solicitation
DIO: DODAG Information Object
DODAG: Destination-Oriented Directed Acyclic Graph DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement NA: Neighbor Advertisement
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery ND: Neighbor Discovery
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NA: Neighbor Advertisement NA: Neighbor Advertisement
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol NDP: Neighbor Discovery Protocol
NS: Neighbor Solicitation NS: Neighbor Solicitation
RA: Router Advertisement RA: Router Advertisement
ROVR: Registration Ownership Verifier (pronounced rover) ROVR: Registration Ownership Verifier
RPI: RPL Packet Information (an Option in the Hop-By_Hop header) RPI: RPL Packet Information (an Option in the Hop-By_Hop Header)
RAL: RPL-Aware Leaf RAL: RPL-Aware Leaf
RS: Router Solicitation RAN: RPL-Aware Node (either a RPL router or a RPL-Aware Leaf)
RPL: IPv6 Routing Protocol for LLNs (pronounced ripple)
RUL: RPL-Unaware Leaf RUL: RPL-Unaware Leaf
TID: Transaction ID (a sequence counter in the EARO) TID: Transaction ID (a sequence counter in the EARO)
3. 6LoWPAN Neighbor Discovery 3. 6LoWPAN Neighbor Discovery
The IPv6 [RFC8200]Neighbor Discovery (IPv6 ND) Protocol (NDP) suite The "IPv6 Neighbor Discovery (IPv6 ND) Protocol" (NDP) suite
[RFC4861] [RFC4862] defined for fast media such a Ethernet, relies [RFC4861] [RFC4862] was defined for transit media such a Ethernet,
heavily on multicast operations for address discovery and duplicate and relies heavily on multicast operations for address discovery and
address detection (DAD). duplicate address detection (DAD).
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
(6LoWPAN ND) adapts IPv6 ND for operations over energy-constrained (6LoWPAN ND) adapts IPv6 ND for operations over energy-constrained
LLNs. In particular, 6LoWPAN ND introduces a unicast host address LLNs. In particular, 6LoWPAN ND introduces a unicast host address
registration mechanism that contributes to reduce the use of registration mechanism that contributes to reducing the use of
multicast messages that are present in the classical IPv6 ND multicast messages that are present in the classical IPv6 ND
protocol. 6LoWPAN ND defines a new Address Registration Option (ARO) protocol. 6LoWPAN ND defines a new Address Registration Option (ARO)
that is carried in the unicast Neighbor Solicitation (NS) and that is carried in the unicast Neighbor Solicitation (NS) and
Neighbor Advertisement (NA) messages between the 6LoWPAN Node (6LN) Neighbor Advertisement (NA) messages between the 6LoWPAN Node (6LN)
and the 6LoWPAN Router (6LR). 6LoWPAN ND also defines the Duplicate and the 6LoWPAN Router (6LR). 6LoWPAN ND also defines the Duplicate
Address Request (DAR) and Duplicate Address Confirmation (DAC) Address Request (DAR) and Duplicate Address Confirmation (DAC)
messages between the 6LR and the 6LoWPAN Border Router (6LBR). In an messages between the 6LR and the 6LoWPAN Border Router (6LBR). In an
LLN, the 6LBR is the central repository of all the Registered LLN, the 6LBR is the central repository of all the Registered
Addresses in its domain. Addresses in its domain.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd | I |R|T| TID | Registration Lifetime | | Rsvd | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier ... ... Registration Ownership Verifier ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Option Format Figure 1: EARO Option Format
The 'R' flag that is set if the Registering Node expects that the 6LR [RFC8505] specifies the use of the R flag in the EARO by the
ensures reachability for the Registered Address, e.g., by means of Registering Node. With [RFC8505], the Registering Node sets the R
routing or proxying ND. flag to indicate whether the 6LR should ensure reachability for the
Registered Address, e.g., by means of routing or proxying ND.
Adapted to this specification, this means that a 6LN operates as a
RUL for an IPv6 address iff it sets the R flag in the NS(EARO) used
to register the address. If the R flag is not set, then the
Registering Node is expected to be a RAN that handles the
reachability of the Registered Address by itself. Conversely, this
document specifies a behavior of a RPL router acting as 6LR for the
registration 6LR that depends on the setting of the R flag in the
NS(EARO). The RPL router generates a DAO message for the Registered
Address upon an NS(EARO) iff the R flag in the EARO is set.
The EARO also includes a sequence counter called Transaction ID The EARO also includes a sequence counter called Transaction ID
(TID), which maps to the Path Sequence Field found in Transit Options (TID), which maps to the Path Sequence Field found in Transit Options
in RPL DAO messages. It is a prerequisite for this specification. in RPL DAO messages. This is the reason why the support of [RFC8505]
by the RUL as opposed to only [RFC6775] is a prerequisite for this
specification (more in Section 6.1). The EARO also transports an
Opaque field and an "I" field that describes what the Opaque field
transports and how to use it.
Finally, the EARO transports an Opaque field and an 'I' field that Section 8.2.1 specifies the use of the R flag, of the "I" field and
describes what the Opaque field transports and how to use it. This of the Opaque field by a RUL.
specification requires that the I field is left to 0 and to use the
Opaque field to carry the RPL InstanceID if one is known, else to "Address Protected Neighbor Discovery for Low-power and Lossy
leave the Opaque field to zero. Networks" [I-D.ietf-6lo-ap-nd] protects the ownership of an address
and enables a challenge that is leveraged by this specification. It
also enables Source Address Validation by a 6LR that will drop the
packets that are sourced at an address that is not registered.
4. Updating RFC 6550 4. Updating RFC 6550
This document specifies a new behavior whereby a 6LR injects DAO This document specifies a new behavior whereby a 6LR injects DAO
messages for unicast addresses registered through the updated 6LoWPAN messages for unicast addresses (see Section 8) and multicast
ND [RFC8505] on behalf of 6LN nodes that are not RPL-aware. addresses (see Section 9) on behalf of leaves that are not aware of
RPL. The Targets are exposed as External addresses. An IP-in-IP
encapsulation that terminates at the border 6LR is used to remove RPL
artifacts and compression techniques that may not be processed
correctly outside of the RPL domain. This specification updates RPL
[RFC6550] to mandate that External Routes are advertised using Non-
Storing Mode signaling even in a Storing-Mode network in order to
inform the root of the address of the 6LR that terminates the IP-in-
IP tunnel.
Upon the renewal of a 6LoWPAN ND registration, this specification [RFC8505] specifies a periodic EDAR/EDAC exchange that takes place
changes the behavior of the 6LR as follows. If the 'R' flag is set, between the 6LR and the 6LBR. It is triggered by a NS(EARO) message
the 6LR injects a DAO targeting the Registered Address, and refrains and is intended to create and then refresh the corresponding state in
from sending a DAR message. the DAR/DAC exchange that refreshes the the 6LBR for a lifetime that is indicated by the 6LN. Conversely,
state in the 6LBR happens instead between the RPL Root and the 6LBR. RPL [RFC6550] specifies a periodic DAO that maintains the routing
In that flow, the RPL Root acts as a proxy on behalf of the 6LR upon state in the RPL network for a lifetime that is indicated by the
the reception of the DAO propagation initiated at the 6LR. source of the DAO. This means that there are two periodic messages
that traverse the whole network to indicate that an address is still
reachable, one to the Root and one to the 6LBR.
This document synchronizes the liveness monitoring at the Root and
the 6LBR. A same value of lifetime is used for both, and a single
keep alive message, the RPL DAO, traverses the RPL network. A new
behavior is introduced whereby the RPL Root proxies the EDAR message
to the 6LBR on behalf of the 6LR (more in Section 5). [RFC6550] is
updated with new RPL Status values for use in DAO-ACK and DCO that
map the 6LoWNAN ND values defined in Table 1 of [RFC8505]. The
Resulting set is shown in Table 1. The Status code are listed in the
same order and DAO-ACK Status code of 128 maps to 6LoWPAN ND Status
Code of 1.
Section 5.3. of [RFC8505] introduces the Registration Ownership
Verifier (ROVR) of a variable length from 64 to 256 bits. A ROVR is
created by the Registering Node and associated to the registration of
an IPv6 Address. It is used to detect a duplication (DAD) and may
also enable the Registering Node to prove its ownership of the
Registered Address [I-D.ietf-6lo-ap-nd]. Section 6.7. of [RFC6550]
introduces the RPL Control Message Options such as the RPL Target
Option that can be included in a RPL Control Message such as the DAO.
This document updates the RPL Target Option to optionally transport a
ROVR, more in Section 7. This enables the RPL Root to generate a
full EDAR Message as opposed to a keep-alive EDAR that has restricted
properties.
5. Updating RFC 8505 5. Updating RFC 8505
The behavior defined in this specification whereby the 6LR that This document updates [RFC8505] to introduce a keep-alive EDAR
processes the registration advertises the Registered Address in DAO message and a keep-alive NS(EARO) message. The keep-alive messages
messages and bypasses the DAR/DAC process for the renewal of a are used for backward compatibility, when the DAO does not transport
registration, is only triggered by an NS(EARO) that has the 'R' flag a ROVR as specified in Section 7. The keep-alive messages have a
set. If the 'R' flag is not set, then the Registering Node is zero ROVR field and can only be used to refresh a pre-existing state
expected to be a RAN router that handles the reachability of the associated to the Registered Address. More specifically, a keep-
Registered Address by itself. alive message can only increase the lifetime and/or increment the TID
of the existing state in a 6LBR.
This document also specifies a keep-alive EDAR message that the RPL Upon the renewal of a 6LoWPAN ND registration, this specification
Root may use to maintain an existing state in the 6LBR upon receiving changes the behavior of a RPL router acting as 6LR for the
DAO messages. The keep-alive EDAR message may only act as a registration as follows: if the Root indicates the capability to
refresher and can only update the Lifetime and the TID of the state proxy the EDAR/EDAC exchange to the 6LBR then the 6LR refrains from
in the 6LBR. sending an EDAR message. If the Root is separated from the 6LBR, the
Root regenerates the EDAR message to the 6LBR upon a DAO message that
signals the liveliness of the Address.
This document similarly specifies a keep-alive NS(EARO) message that 6. 6LN Requirements to be a RPL-Unware Leaf
the RPL Root may use to maintain an existing state in a 6BBR upon
receiving DAO messages. The keep-alive NS(EARO) message may only act
as a refresher and can only update the Lifetime and the TID of the
state in the 6BBR.
As prescribed by [RFC8505], a RPL router SHOULD NOT set the 'R' flag. This document provides RPL routing for a RUL, that is a 6LN acting as
a plain host and not aware of RPL. Still, a minimal RPL-independent
functionality is expected from the 6LN in order to obtain routing
services from the 6LR.
6. Dependencies on the 6LN 6.1. Support of 6LoWPAN ND
This document provides RPL routing for a 6LN acting as a plain host A RUL MUST implement [RFC8505] and set the R flag in the EARO option.
and not aware of RPL. Still, a minimal RPL-independent functionality A 6LN is considered to be a RUL if and only if it sets the R flag in
is expected from the 6LN in order to operate properly as a RLU; in the EARO.
particular:
o the 6LN MUST implement [RFC8505] and set the 'R' flag in the EARO A RUL SHOULD implement [RFC8505] and set the R flag in the EARO
option. The 'R' flag is used to determine whether the Registering option. A 6LN is considered to be a RUL if and only if it sets the R
Node is a RUL, not aware of the RPL operation in the network, and flag in the EARO.
thus does not participate to it. A 6LN is considered to be a RUL
if and only if it sets the 'R' flag in the EARO.
o RPL data packets are often encapsulated using IP in IP and in Non- [RFC8505] introduces error Status values in the NA(EARO) which can be
Storing Mode, packets going down will carry an SRH as well. RPL received synchronously upon an NS(EARO) or asynchronously. The RUL
data packets also typically carry a Hop-by-Hop Header to transport MUST support both cases and refrain from using the Registered Address
a RPL Packet Information (RPI) [RFC6550]. These additional as suggested by [RFC8505] depending on the Status value.
headers are called RPL artifacts.
o An arbitrary 6LN is expected to support IPv6-in-IPv6 encapsulation A RUL SHOULD supports [I-D.ietf-6lo-ap-nd] to protect the ownership
when it is the destination of the outer header. If the 6LN is a of its addresses.
host, it is expected to drop the inner packet if it is not the
destination of the inner header.
o An arbitrary 6LN is expected to process an unknown Option Type in 6.2. External Routes and RPL Artifacts
a Hop-by-Hop Header as prescribed by section 4.2 of [RFC8200].
This means in particular that an RPI with an Option Type of 0x23
[I-D.ietf-roll-useofrplinfo] is ignored when not understood.
o An arbitrary 6LN is expected to process an unknown Routing Header RPL data packets are often encapsulated using IP-in-IP and in Non-
Type as prescribed by section 4.4 of [RFC8200]. This means in Storing Mode, packets going down will carry an SRH as well. RPL data
particular that Routing Header with a Routing Type of 3 [RFC6553] packets also typically carry a Hop-by-Hop Header to transport a RPL
is ignored when the Segments Left is zero, and dropped otherwise. Packet Information (RPI) [RFC6550]. These additional headers are
called RPL artifacts. When IP-in-IP is used and the outer headers
terminate at a 6LR down the path (see Figure 8 for the format in
Storing Mode), then the 6LR decapsulates the IP-in-IP and the packet
that is forwarded to the external destination is free of RPL
artifacts.
o When IP-in-IP is used and the outer headers terminate at the 6LR IP-in-IP to the 6LR MUST be used if the final destination cannot
that generated the DAO, then the 6LR decapsulates the packet to handle or ignore the RPL artifacts or the way they are compressed
the 6LN ( see Appendix A for the format in Storing Mode). In that [RFC8138]. An External route indicates by default a node or a prefix
case the 6LN gets a packet that is free of RPL artifacts. IP-in- that is not known to handle or ignore the RPL artifacts. The
IP to the 6LR MUST be used if the 6LN cannot handle or ignore the RECOMMENDED behaviour when using IP-in-IP to an External route is
RPL artifacts or the way they are compressed [RFC8138]. It SHOULD that the outer headers terminate at the 6LR that injected the
be used it there is a particular bandwidth or power constraint at External route. Non-Storing Mode signaling MUST be used to inject
the 6LN that justifies saving the encapsulation at the last hop. External routes to the Root in order to advertise the 6LR that is
associated to a RUL.
o In order to save the IP-in-IP encapsulation and to support Storing In order to save the IP-in-IP encapsulation and to support Storing
Mode of operation, it is preferred that the 6LN can ignore an RPI Mode of operation, it is preferred that the 6LN can ignore an RPI and
and consume a routing header in both the native and compressed consume a routing header in both the native and [RFC8138]-compressed
forms. In order to enable IP-in-IP to a 6LN in Non-Storing Mode, forms. In order to enable IP-in-IP to a 6LN in Non-Storing Mode, it
it is also of interest that the 6LN supports decapsulating IP-in- is also of interest that the 6LN supports decapsulating IP-in-IP in
IP in both forms. But since the preferred behaviour when using both forms.
IP-in-IP is that the outter headers terminate at the 6LR,
supporting this capability is secondary.
7. Protocol Operations for Unicast Addresses 6.2.1. Support of the HbH Header
7.1. General Flow A RUL is expected to process an unknown Option Type in a Hop-by-Hop
Header as prescribed by section 4.2 of [RFC8200]. This means in
particular that an RPI with an Option Type of 0x23
[I-D.ietf-roll-useofrplinfo] is ignored when not understood.
6.2.2. Support of the Routing Header
A RUL is expected to process an unknown Routing Header Type as
prescribed by section 4.4 of [RFC8200]. This means in particular
that Routing Header with a Routing Type of 3 [RFC6553] is ignored
when the Segments Left is zero, and dropped otherwise.
6.2.3. Support of IPv6 Encapsulation
A RUL may support IPv6-in-IPv6 decapsulation when it is the
destination of the outer header but that is not assumed by [RFC8504].
If the 6LN is a RUL, it may be able to drop the inner packet if it is
not the destination of the inner header. By default the IP-in-IP
tunnel should terminate at the parent 6LR so supporting this
capability in a RUL is secondary.
7. Updated RPL Target option
This specification updates the RPL Target option to transport the
ROVR as illustrated in Figure 2. The Target Prefix MUST be aligned
to the next 4-byte boundary after the size indicated by the Prefix
Length. if necessary it is padded with zeros. The size of the ROVR
is indicated in a new ROVR Type field that is encoded to map the
CodePfx in the EDAR message (see section 4.2 of [RFC8505]). With
this specification the ROVR is the remainder of the RPL Target
Option.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x05 | Option Length |ROVRsz | Flags | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Target Prefix (Variable Length) |
. Aligned to 4-byte boundary .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
... Registration Ownership Verifier (ROVR) ...
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Updated Target Option
New fields:
RVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3,
or 4, denoting a ROVR size of 64, 128, 192, or 256
bits, respectively.
Registration Ownership Verifier (ROVR): This is the same field as in
the EARO, see [RFC8505]
8. Protocol Operations for Unicast Addresses
8.1. General Flow
This specification enables to save the exchange of Extended Duplicate This specification enables to save the exchange of Extended Duplicate
Address messages, EDAR and EDAC, from a 6LN all the way to the 6LBR Address messages, EDAR and EDAC, from a 6LN all the way to the 6LBR
across a RPL mesh, for the sole purpose of refreshing an existing across a RPL mesh, for the sole purpose of refreshing an existing
state in the 6LBR. Instead, the EDAR/EDAC exchange is proxied by the state in the 6LBR. Instead, the EDAR/EDAC exchange is proxied by the
RPL Root upon a DAO message that refreshes the RPL routing state. To RPL Root upon a DAO message that refreshes the RPL routing state. To
achieve this, the lifetimes and sequence counters in 6LoWPAN ND and achieve this, the lifetimes and sequence counters in 6LoWPAN ND and
RPL are aligned. In other words, the Path Sequence and the Path RPL are aligned. In other words, the Path Sequence and the Path
Lifetime in the DAO message are derived from the Transaction ID and Lifetime in the DAO message are taken from the Transaction ID and the
the registration lifetime in the NS(EARO) message from the 6LN. registration lifetime in the NS(EARO) message from the 6LN.
In that flow, the RPL Root acts as a proxy to refresh the state in
the 6LBR. The proxy operation applies to both RUL and RAN. This
means that in a RPL network where the function is enabled, refreshing
the state in the 6LBR is the responsibility of the Root.
Consequently, only addresses that are injected in RPL will be kept
alive by the RPL Root. If an additional routing protocol is deployed
on a same network, that additional routing protocol may need to
handle the keep alive procedure for the addresses that it serves.
From the perspective of the 6LN, the registration flow happens From the perspective of the 6LN, the registration flow happens
transparently; it is not delayed by the proxy RPL operation, so the transparently; it is not delayed by the proxy RPL operation, so the
device does not need to wait more whether RPL proxy operation happens device does not need to change the amount of time it waits based upon
or not. The flows below are RPL Non-Storing Mode examples. In whether RPL proxy operation happens or not.
Storing Mode, the DAO ACK may not be present, and the DAO messages
cascade from child to parent all the way to the DODAG Root.
On the first registration, illustrated in Figure 2, from the On the first registration, illustrated in Figure 3, from the
perspective of the 6LR in Non-Storing Mode, the Extended Duplicate perspective of the 6LR in Non-Storing Mode, the Extended Duplicate
Address message takes place as prescribed by [RFC8505]. When Address message takes place as prescribed by [RFC8505]. When
successful, the flow creates a Neighbor Cache Entry (NCE) in the 6LR, successful, the flow creates a Neighbor Cache Entry (NCE) in the 6LR,
and the 6LR injects the Registered Address in RPL using DAO/DAO-ACK and the 6LR injects the Registered Address in RPL using DAO/DAO-ACK
exchanges all the way to the RPL DODAG Root. The protocol does not exchanges all the way to the RPL DODAG Root. The protocol does not
carry a specific information that the Extended Duplicate Address carry a specific information that the Extended Duplicate Address
messages were already exchanged, so the Root proxies them anyway. messages were already exchanged, so the Root proxies them anyway.
Note that in Storing Mode the DAO ACK is generated from the parent
that does not necessary wait for the grand parent to acknowledge, so Note that any of the functions 6LR, Root and 6LBR might be collapsed
the DAO-ACK is no guarantee that the keep-alive EDAR succeeded. On in a single node, in which case the flow above happens internally,
the other hand, the flows can be nested in Non-Storing Mode, and it and possibly through internal API calls as opposed to messaging.
is possible to carry information such as an updated lifetime from the
6LBR all the way to the 6LN. 8.1.1. In RPL Non-Storing-Mode
In Non-Storing Mode, the flows can be nested as illustrated in
Figure 3 and it is possible to carry information such as an updated
lifetime from the 6LBR all the way to the 6LN.
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | Extended DAR | | | Extended DAR |
| |-------------------------------->| | |-------------------------------->|
| | | | | |
| | Extended DAC | | | Extended DAC |
| |<--------------------------------| | |<--------------------------------|
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | | keep-alive EDAR | | | | keep-alive EDAR |
| | |---------------->| | | |---------------->|
| | | EDAC | | | | EDAC |
| | |<----------------| | | |<----------------|
| | DAO ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| NA(EARO) | | | NA(EARO) | |
|<---------------| | | |<---------------| | |
| | | | | | | |
(in case if an Error not reported in DAO-ACK)
| | | |
| | DCO | |
| |<--------------| |
| NA(EARO) | | |
|<---------------| | |
| | | |
Figure 2: First Registration Flow Figure 3: First Registration Flow in Non-Storing Mode
A re-registration is performed by the 6LN to maintain the NCE in the A re-registration is performed by the 6LN to maintain the NCE in the
6LR alive before lifetime expires. Upon a re-registration, as 6LR alive before lifetime expires. Upon a re-registration, as
illustrated in Figure 3, the 6LR redistributes the Registered Address illustrated in Figure 4, the 6LR redistributes the Registered Address
NS(EARO) in RPL. This causes the RPL DODAG Root to refresh the state NS(EARO) in RPL.
in the 6LBR with a keep-alive EDAC message. The keep-alive EDAC
lacks the Registration Ownership Verifier (ROVR) information, since This causes the RPL DODAG Root to refresh the state in the 6LBR with
it is not present in RPL DAO messages, but the EDAC message sent in a keep-alive EDAC message. The keep-alive EDAC lacks the
response by the 6LBR contains the actual value of the ROVR field for Registration Ownership Verifier (ROVR) information, since it is not
that registration. This enables the RPL Root to perform the proxy- present in RPL DAO messages, but the EDAC message sent in response by
the 6LBR contains the actual value of the ROVR field for that
registration. This enables the RPL Root to perform the proxy-
registration for the Registered Address and attract traffic captured registration for the Registered Address and attract traffic captured
over the backbone by the 6BBR and route it back to the device. over the backbone by the 6BBR and route it back to the device.
6LN 6LR Root 6LBR 6BBR 6LN 6LR Root 6LBR
| | | | | | | | |
| NS(EARO) | | | | | NS(EARO) | | |
|-------------->| | | | |--------------->| |
| NA(EARO) | | | | | | DAO | |
|<--------------| | | | | |-------------->| |
| | | | | | | | keep-alive EDAR |
| | DAO | | | | | |---------------->|
| |-------------->| | | | | | EDAC |
| | | | | | | |<----------------|
| | | keep-alive EDAR | | | | DAO-ACK | |
| | |---------------->| | | |<--------------| |
| | | EDAC(ROVR) | | | NA(EARO) | |
| | |<----------------| | |<---------------| | |
| | | | | | | | |
| | | proxy NS(EARO) |
| | |------------------------------->|
| | | proxy NA(EARO) |
| | |<-------------------------------|
| | | | |
| | DAO ACK | | |
| |<--------------| | |
| | | | |
Figure 3: Next Registration Flow Figure 4: Next Registration Flow in Non-Storing Mode
Note that any of the functions 6LR, Root and 6LBR might be collapsed In case of an error on the keep-alive EDAR flow, the error SHOULD be
in a single node, in which case the flow above happens internally, returned in the DAO-ACK - if one was requested - using the mapping of
and possibly through internal API calls as opposed to messaging. RPL Status and 6LoWPAN Status values discussed in Section 4.
7.2. 6LN Operation If the Root could not return the negative Status in the DAO-ACK then
it sends an asynchronous Destination Cleanup Object (DCO) message
[I-D.ietf-roll-efficient-npdao] to the 6LR indicating the issue with
the mapped Status value. Note that if both are used in a short
interval of time, the DAO-ACK and DCO messages are not guaranteed to
arrive in the same order at the 6LR. So the 6LR must still expect a
DAO-ACK even if it received a DCO while it was waiting for an
acknowledgement for a short period of time, but the negative status
in the DCO supercedes a positive status in the DAO-ACK regardless of
the order in which they are received.
Upon the DAO-ACK - or the DCO if it arrives first - the 6LR responds
to the RUL with a NA(EARO) and the 6LoWPAN ND Status value that is
mapped from the RPL status in the RPL message. An asynchronous DCO
is also mapped in an asynchronous NA(EARO) to the RUL with a mapped
Status value.
8.1.2. In RPL Storing-Mode
In Storing Mode, the DAO-ACK is optional. When it is used, it is
generated by the RPL parent, which does not need to wait for the
grand-parent to send the acknowledgement. A successful DAO-ACK is
not a guarantee that the DAO has yet reached the Root or that the
keep-alive EDAR has succeeded.
If the keep alive fails, the path is cleaned up asynchronously using
a DCO message [I-D.ietf-roll-efficient-npdao] as illustrated in
Figure 5 and described in further details in Section 8.2.3.
6LN 6LR 6LR Root 6BBR
| | | | |
| NS(EARO) | | | |
|-------------->| | | |
| NA(EARO) | | | |
|<--------------| | | |
| | | | |
| | DAO | | |
| |-------------->| | |
| | DAO-ACK | | |
| |<--------------| | |
| | | | |
| | | DAO | |
| | |-------------->| |
| | | DAO-ACK | |
| | |<--------------| |
| | | | |
| | | | keep-alive EDAR |
| | | |---------------->|
| | | | EDAC(ROVR) |
| | | |<----------------|
| | | | |
(in case if an Error)
| | | | |
| | DCO | |
| |<------------------------------| |
| NA(EARO) | | | |
|<--------------| | | |
| | | | |
Figure 5: Next Registration Flow in Storing Mode
8.2. Operation
8.2.1. By the 6LN
This specification does not alter the operation of a 6LoWPAN ND- This specification does not alter the operation of a 6LoWPAN ND-
compliant 6LN, which is expected to operate as follows: compliant 6LN, and a RUL is expected to operate as follows:
o The 6LN obtains an IPv6 global address, for instance using o The 6LN obtains an IPv6 global address, for instance using
autoconfiguration [RFC4862] based on a Prefix Information Option autoconfiguration [RFC4862] based on a Prefix Information Option
(PIO) [RFC4861] found in a Router Advertisement message or by some (PIO) [RFC4861] found in a Router Advertisement message or by some
other means such as DHCPv6 [RFC3315]. other means such as DHCPv6 [RFC3315].
o Once it has formed an address, the 6LN (re)registers its address o Once it has formed an address, the 6LN (re)registers its address
periodically, within the Lifetime of the previous registration, as periodically, within the Lifetime of the previous registration, as
prescribed by [RFC8505]. prescribed by [RFC6775].
o Upon each consecutive registration, the 6LN MUST increase the TID
field.
o If the 6LN is aware of the RPL Instance the packet should be o A 6LN acting as a RUL sets the R flag in the EARO whereas a 6LN
injected into, then it SHOULD set the Opaque field to the acting as a RAN does not set the R flag as prescribed by [RFC8505]
InstanceID, else it MUST leave the Opaque field to zero. In any section 5.1.
fashion the 6LN MUST set the 'I' field to zero.
o A 6LN acting as a RUL MUST set the 'R' flag in the EARO whereas a o Upon each consecutive registration, the 6LN increases the TID
6LN acting as a RAN SHOULD NOT set the 'R' flag. field in the EARO, as prescribed by [RFC8505] section 5.2.
o The 6LN MAY register to more than one 6LR at the same time. In o The 6LN can register to more than one 6LR at the same time. In
that case, a same value of TID is used for each registration. that case, a same value of TID is used for each registration.
o The 6LN MAY use any of the 6LRs to which it register to forward o The 6LN may use any of the 6LRs to which it register to forward
its packets. its packets. Using a 6LR to which the 6LN is not registered may
result in packets dropped by a Source Address Validation function.
o the 6LN is not expected to be aware of RPL so it is not expected Even without support for RPL, a RUL may be aware of opaque values to
to produce RPL artifacts in the data packets. be provided to the routing protocol. If the RUL has a knowledge of
the RPL Instance the packet should be injected into, then it SHOULD
set the Opaque field in the EARO to the RPLInstanceID, else it MUST
leave the Opaque field to zero. In any fashion the 6LN MUST set the
"I" field to zero to indicate that topological information to be
passed to a routing process as specified in [RFC8505] section 5.1.
7.3. 6LR Operation A RUL is not expected to produce RPL artifacts in the data packets,
but it MAY do so. for instance, if the RUL has a minimal awareness of
the RPL Instance and can build an RPI. A RUL that places an RPI in a
data packet MUST indicate the RPLInstanceID that corresponds to the
RPL Instance the packet should be injected into. All the flags and
the Rank field are set to zero as specified by section 11.2 of
[RFC6550].
8.2.2. By the 6LR
Also as prescribed by [RFC8505], the 6LR generates a DAR message upon Also as prescribed by [RFC8505], the 6LR generates a DAR message upon
reception of a valid NS(EARO) message for the registration of a new reception of a valid NS(EARO) message for the registration of a new
IPv6 Address by a 6LN. If the Duplicate Address exchange succeeds, IPv6 Address by a 6LN. If the Duplicate Address exchange succeeds,
then the 6LR installs a Neighbor Cache Entry (NCE). If the 'R' flag then the 6LR installs a Neighbor Cache Entry (NCE). If the R flag
was set in the EARO of the NS message, and this 6LR can manage the was set in the EARO of the NS message, and this 6LR can manage the
reachability of Registered Address, then the 6LR sets the 'R' flag in reachability of Registered Address, then the 6LR sets the R flag in
the ARO of the response NA message. the EARO of the NA message that is sent in response.
From then on, the 6LN periodically sends a new NS(EARO) to refresh From then on, the 6LN periodically sends a new NS(EARO) to refresh
the NCE state before the lifetime indicated in the EARO expires, with the NCE state before the lifetime indicated in the EARO expires, with
TID that is incremented each time till it wraps in a lollipop TID that is incremented each time till it wraps in a lollipop fashion
fashion. As long as the 'R' flag is set and this router can still (see section 5.2.1 of [RFC8505] which is fully compatible with
manage the reachability of Registered Address, the 6LR keeps setting section 7.2 of [RFC6550]). As long as the R flag is set and this
the 'R' flag in the EARO of the response NA message, but the exchange router can still manage the reachability of Registered Address, the
of Extended Duplicate Address messages is skipped. 6LR keeps setting the R flag in the EARO of the response NA message,
but the exchange of Extended Duplicate Address messages is skipped.
The Opaque field in the EARO hints the 6LR on the RPL Instance that The Opaque field in the EARO hints the 6LR on the RPL Instance that
should be used for the DAO advertisements, and for the forwarding of should be used for the DAO advertisements, and for the forwarding of
packets sourced at the registered address when there is no RPL Packet packets sourced at the registered address when there is no RPL Packet
Information (RPI) in the packet, in which case the 6LR SHOULD add one Information (RPI) in the packet, in which case the 6LR SHOULD add one
to the packet. if the 'I' field is not zero, then the 6LR MUST to the packet. if the "I" field is not zero, then the 6LR MUST
consider that the Opaque field is left to zero. If the Opaque field consider that the Opaque field is zero. If the Opaque field is not
is not set to zero, then it should carry a RPL InstanceID for the set to zero, then it should carry a RPLInstanceID for the Instance
Instance suggested by the 6LN. If the 6LR does not participate to suggested by the 6LN. If the 6LR does not participate to the
the associated Instance, then the 6LR MUST consider that the Opaque associated Instance, then the 6LR MUST consider that the Opaque field
field is left to zero. If the Opaque field left to zero, the 6LR is is empty. If the Opaque field is empty, the 6LR is free to use the
free to use the default Instance (zero) for the registered address or default Instance (zero) for the registered address or to select an
to select an Instance of its choice; else, that is if the 6LR Instance of its choice; else, that is if the 6LR participates to the
participates to the suggested Instance, then the 6LR SHOULD use that suggested Instance, then the 6LR SHOULD use that Instance for the
Instance for the registered address. registered address.
Upon a successful NS/NA(EARO) exchange: if the 'R' flag was set in Upon a successful NS/NA(EARO) exchange: if the R flag was set in the
the EARO of the NS message, then the 6LR SHOULD inject the Registered EARO of the NS message, then the 6LR SHOULD inject the Registered
Address in RPL by sending a DAO message on behalf of the 6LN; else Address in RPL by sending a DAO message on behalf of the 6LN; else
the 6LR MUST NOT inject the Registered Address into RPL. the 6LR MUST NOT inject the Registered Address into RPL.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
o The Registered Address is placed in a RPL Target Option in the DAO o The Registered Address is placed in a RPL Target Option in the DAO
message as the Target Prefix, and the Prefix Length is set to 128 message as the Target Prefix, and the Prefix Length is set to 128;
o the External 'E' flag in the Transit Information Option (TIO) o the External 'E' flag in the Transit Information Option (TIO)
associated to the Target Option is set to indicate that the 6LR associated to the Target Option is set to indicate that the 6LR
redistributes an external target into the RPL network. This is redistributes an external target into the RPL network. When the
how the Root knows in Non-Storing Mode to use IP-in-IP and Root has to use an IP-in-IP [I-D.ietf-roll-useofrplinfo], then
terminate the outters headers at the 6LR that generated the DAO. this flag indicates the IP-in-IP should be addressed to this node;
o the Path Lifetime in the TIO is computed from the Lifetime in the o the Path Lifetime in the TIO is computed from the Lifetime in the
EARO Option to adapt it to the Lifetime Units used in the RPL EARO Option to adapt it to the Lifetime Units used in the RPL
operation. Note that if the lifetime is 0, then the 6LR generates operation. Note that if the lifetime is 0, then the 6LR generates
a No-Path DAO message that cleans up the routes down to the a No-Path DAO message that cleans up the routes down to the
Address of the 6LN. Address of the 6LN;
o the Path Sequence in the TIO is set to the TID value found in the o the Path Sequence in the TIO is set to the TID value found in the
EARO option. EARO option;
o Additionally, in Non-Storing Mode the 6LR indicates one of its o Additionally, in Non-Storing Mode the 6LR indicates one of its
global IPv6 unicast addresses as the Parent Address in the TIO. global IPv6 unicast addresses as the Parent Address in the TIO.
If a 6LR receives a valid NS(EARO) message with the 'R' flag reset If a DAO-ACK is not requested, or has a Status that is less than 128,
and the 6LR was redistributing the Registered Address due to previous indicating the DAO was accepted, respectively by a parent in Storing
Mode or by the Root in non-Storing Mode,, the 6LR replies with a
NA(EARO) to the RUL with a status of 0 (Success).
In case of a DAO-ACK or a DCO with a status of 132 (Validation
Requested) the 6LR challenges the 6LN for ownership of the address,
as described in section 6.1 of [RFC8505]. If the challenge succeeds
then the operations continue as normal. In particular a DAO message
is generated upon the NS(EARO) that proves the ownership of the
address. If the challenge failed the 6LR MUST refrain from injecting
the address in RPL and may take actions to protect itself against DoS
attacks by a rogue 6LN, see Section 11
Other status values above 128 indicate that the 6LR failed to inject
the address into the RPL network. In that case the the 6LR MUST send
a NA(EARO) to the RUL with the mapped Status value. If for any other
reason the 6LR fails to inject the address into the RPL network, the
6LR SHOULD send a NA(EARO) to the RUL with a status of 2 (Out of
Storage) which indicates a possibility to retry later.
If a 6LR receives a valid NS(EARO) message with the R flag reset and
the 6LR was redistributing the Registered Address due to previous
NS(EARO) messages with the flag set, then it MUST stop injecting the NS(EARO) messages with the flag set, then it MUST stop injecting the
address. It is up to the Registering Node to maintain the address. It is up to the Registering Node to maintain the
corresponding route from then on, either keeping it active by sending corresponding route from then on, either keeping it active by sending
further DAO messages, or destroying it using a No-Path DAO. further DAO messages, or destroying it using a No-Path DAO.
7.4. RPL Root Operation Upon a DCO message indicating that the address of a RUL should be
removed from the routing table, the 6LR issues an asynchronous
NA(EARO) to the RUL with the mapped Status value.
8.2.3. By the RPL Root
In RPL Storing Mode of Operation (MOP), the DAO message is propagated In RPL Storing Mode of Operation (MOP), the DAO message is propagated
from child to parent all the way to the Root along the DODAG, from child to parent all the way to the Root along the DODAG,
populating routing state as it goes. In Non-Storing Mode, The DAO populating routing state as it goes. In Non-Storing Mode, The DAO
message is sent directly to the route. Upon reception of a DAO message is sent directly to the RPL Root. Upon reception of a DAO
message that creates or updates an existing RPL state: message, for each RPL Target option that creates or updates an
existing RPL state:
o the Root notifies the 6LBR using an internal API if they are
collocated, or performs a keep-alive DAR/DAC exchange on behalf of
the registering node if they are separated.
o In an extended topology with a Backbone Link, the Root notifies o the Root notifies the 6LBR using an internal API if they are co-
the 6LBR by proxying a keep-alive NS(EARO) on behalf of the 6LN located, or performs an EDAR/EDAC exchange on behalf of the 6LR if
that owns the address indicated in the Target Option. they are separated. If the Target option transports a ROVR, then
the Root MUST use it to build a full EDAR message as the 6LR
would. Else, a keep-alive EDAR is used with the ROVR field set to
zero.
The keep-alive EDAR and the NS(EARO) messages MUST be constructed as An EDAR message MUST be constructed as follows:
follows:
o The Target IPv6 address from in the RPL Target Option is placed in o The Target IPv6 address from in the RPL Target Option is placed in
the Registered Address field of the EDAR message and in the Target the Registered Address field of the EDAR message and in the Target
field of the NS message, respectively field of the NS message, respectively;
o the ROVR field in the keep-alive EDAR is set to 64-bits of all
ones to indicate that it is not provided and this is a keep-alive
EDAR. The actual value of the ROVR for that registration is
returned by the 6LBR in an EDAC, and used in the proxy NS(EARO).
o the Registration Lifetime is adapted from the Path Lifetime in the o the Registration Lifetime is adapted from the Path Lifetime in the
TIO by converting the Lifetime Units used in RPL into units of 60 TIO by converting the Lifetime Units used in RPL into units of 60
seconds used in the 6LoWPAN ND messages. seconds used in the 6LoWPAN ND messages;
o The RPL Root indicates its own MAC Address as Source Link Layer o the RPL Root indicates its own MAC Address as Source Link Layer
Address (SLLA) in the NS(EARO). Address (SLLA) in the NS(EARO);
o the TID value is set to the Path Sequence in the TIO. The 'T' o the TID value is set to the Path Sequence in the TIO and indicated
flag and an ICMP code of 1 are used in the NS(EARO) and the DAR with an ICMP code of 1 in the EDAR message;
message, respectively.
Upon a status in a DAC message that is not "Success", the Root MAY o when present in the RPL Target option, the ROVR field is used as
destroy the formed paths using a No-Path DAO downwards as specified is in the EDAR and the ICMP Code Suffix is set to the appropriate
in [I-D.ietf-roll-efficient-npdao]. value as shown in Table 4 of [RFC8505] depending on the length of
the ROVR field. If it is not present the ROVR field in the EDAR
is set to zero indicating that this is a keep-alive EDAR. The
actual value of the ROVR for that registration is expected from
the 6LBR in the response EDAC.
In Non-Storing Mode, the outer IPv6 header that is used by the Root Upon a Status value in an EDAC message that is not "Success", the
to transport the source routing information in data packets down the Root SHOULD destroy the formed paths using either a DAO-ACK (in Non-
DODAG has the 6LR that serves the 6LN as final destination. This Storing Mode) or a DCO downwards as specified in
way, when the final 6LR decapsulates the outer header, it also [I-D.ietf-roll-efficient-npdao]. Failure to destroy the former path
removes all the RPL artifacts from the packet. would result in Stale routing state and local black holes if the
address belongs to another party elsewhere in the network. The RPL
Status value that maps the 6LowpAN ND status value MUST be placed in
the DCO.
7.5. 6LBR Operation 8.2.4. By the 6LBR
Upon reception of a DAR message with the Owner Unique ID field is set Upon reception of an EDAR message with the ROVR field is set to zero
to all ones, the 6LBR checks whether an entry exists for the and indicating a keep-alive EDAR, the 6LBR checks whether an entry exists
computes whether the TID in the DAR message is fresher than that in for the and computes whether the TID in the DAR message is fresher
the entry as prescribed in section 4.2.1. of [RFC8505]. than that in the entry as prescribed in section 4.2.1. of [RFC8505].
If the entry does not exist, the 6LBR does not create the entry, and If the entry does not exist, the 6LBR does not create the entry, and
answers with a Status "Removed" in the DAC message. answers with a Status "Removed" in the EDAC message.
If the entry exists but is not fresher, the 6LBR does not update the If the entry exists but is not fresher, the 6LBR does not update the
entry, and answers with a Status "Success" in the DAC message. entry, and answers with a Status "Success" in the EDAC message.
If the entry exists and the TID in the DAR message is fresher, the If the entry exists and the TID in the DAR message is fresher, the
6LBR updates the TID in the entry, and if the lifetime of the entry 6LBR updates the TID in the entry, and if the lifetime of the entry
is extended by the Registration Lifetime in the DAR message, it also is extended by the Registration Lifetime in the DAR message, it also
updates the lifetime of the entry. In that case, the 6LBR replies updates the lifetime of the entry. In that case, the 6LBR replies
with a Status "Success" in the DAC message. with a Status "Success" in the DAC message.
8. Protocol Operations for Multicast Addresses The EDAC that is constructed is the same as if the keep-alive EDAR
was a full EDAR, and includes the ROVR that is associated to the
registration.
9. Protocol Operations for Multicast Addresses
Section 12 of [RFC6550] details the RPL support for multicast flows. Section 12 of [RFC6550] details the RPL support for multicast flows.
This support is not source-specific and only operates as an extension This support is not source-specific and only operates as an extension
to the Storing Mode of Operation for unicast packets. Note that it to the Storing Mode of Operation for unicast packets. Note that it
is the RPL model that the multicast packet is passed as a Layer-2 is the RPL model that the multicast packet is passed as a Layer-2
unicast to each if the interested children. This remains true when unicast to each if the interested children. This remains true when
forwarding between the 6LR and the listener 6LN. forwarding between the 6LR and the listener 6LN.
"Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its "Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its
updated version "Multicast Listener Discovery Version 2 (MLDv2) for updated version "Multicast Listener Discovery Version 2 (MLDv2) for
IPv6" [RFC3810] provide an interface for a listener to register to IPv6" [RFC3810] provide an interface for a listener to register to
multicast flows. MLDv2 is backwards compatible with MLD, and adds in multicast flows. MLDv2 is backwards compatible with MLD, and adds in
particular the capability to filter the sources via black lists and particular the capability to filter the sources via black lists and
white lists. In the MLD model, the router is a "querier" and the white lists. In the MLD model, the router is a "querier" and the
host is a multicast listener that registers to the querier to obtain host is a multicast listener that registers to the querier to obtain
copies of the particular flows it is interested in. copies of the particular flows it is interested in.
On the first registration, as illustrated in Figure 4, the 6LN, as an On the first registration, as illustrated in Figure 6, the 6LN, as an
MLD listener, sends an unsolicited Report to the 6LR in order to MLD listener, sends an unsolicited Report to the 6LR in order to
start receiving the flow immediately. Since multicast Layer-2 start receiving the flow immediately. Since multicast Layer-2
messages are avoided, it is important that the asynchronous messages messages are avoided, it is important that the asynchronous messages
for unsolicited Report and Done are sent reliably, for instance using for unsolicited Report and Done are sent reliably, for instance using
an Layer-2 acknoledgement, or attempted multiple times. an Layer-2 acknoledgement, or attempted multiple times.
The 6LR acts as a generic MLD querier and generates a DAO for the The 6LR acts as a generic MLD querier and generates a DAO for the
multicast target. The lifetime of the DAO is set to be in the order multicast target. The lifetime of the DAO is set to be in the order
of the Query Interval, yet larger to account for variable propagation of the Query Interval, yet larger to account for variable propagation
delays. delays.
skipping to change at page 16, line 12 skipping to change at page 21, line 12
it is already registered as a listener for that address, and if not, it is already registered as a listener for that address, and if not,
it performs its own unsolicited Report for the multicast target. it performs its own unsolicited Report for the multicast target.
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| unsolicited Report | | | | unsolicited Report | | |
|------------------->| | | |------------------->| | |
| <L2 ack> | | | | <L2 ack> | | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | <if not listening> | | | | <if not listening> |
| | | unsolicited Report | | | | unsolicited Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 4: First Multicast Registration Flow Figure 6: First Multicast Registration Flow
A re-registration is pulled by 6LR acting as querier. Note that the A re-registration is pulled by 6LR acting as querier. Note that the
message may sent unicast to all the known individual listeners. Upon message may sent unicast to all the known individual listeners. Upon
a time out of the Query Interval, the 6LR sends a Query to each of a time out of the Query Interval, the 6LR sends a Query to each of
its listeners, and gets a Report back that is mapped into a DAO, as its listeners, and gets a Report back that is mapped into a DAO, as
illustrated in Figure 5, illustrated in Figure 7,
6LN 6LR Root 6LBR 6LN 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | | | | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 5: Next Registration Flow Figure 7: Next Registration Flow
Note that any of the functions 6LR, Root and 6LBR might be collapsed Note that any of the functions 6LR, Root and 6LBR might be collapsed
in a single node, in which case the flow above happens internally, in a single node, in which case the flow above happens internally,
and possibly through internal API calls as opposed to messaging. and possibly through internal API calls as opposed to messaging.
9. Implementation Status 10. Implementation Status
10. Security Considerations 11. Security Considerations
The LLN nodes depend on the 6LBR and the RPL participants for their The LLN nodes depend on the 6LBR and the RPL participants for their
operation. A trust model must be put in place to ensure that the operation. A trust model must be put in place to ensure that the
right devices are acting in these roles, so as to avoid threats such right devices are acting in these roles, so as to avoid threats such
as black-holing, or bombing attack whereby an impersonated 6LBR would as black-holing, (see [RFC7416] section 7) or bombing attack whereby
destroy state in the network by using the "Removed" Status code. an impersonated 6LBR would destroy state in the network by using the
This trust model could be at a minimum based on a Layer-2 access "Removed" Status code. This trust model could be at a minimum based
control, or could provide role validation as well. This is a generic on a Layer-2 access control, or could provide role validation as
6LoWPAN requirement, see Req5.1 in Appendix of [RFC8505]. well. This is a generic 6LoWPAN requirement, see Req5.1 in
Appendix of [RFC8505].
The keep-alive EDAR message does not carry a valid Registration The keep-alive EDAR message does not carry a valid Registration
Unique ID [RFC8505] and it cannot be used to create a binding state Unique ID [RFC8505] and it cannot be used to create a binding state
in the 6LBR. The 6LBR MUST NOT create an entry based on a keep-alive in the 6LBR. The 6LBR MUST NOT create an entry based on a keep-alive
EDAR that does not match an existing entry. All it can do is refresh EDAR that does not match an existing entry. All it can do is refresh
the lifetime and the TID of an existing entry. the lifetime and the TID of an existing entry.
11. IANA Considerations At the time of this writing RPL does not have a zerotrust model
whereby the it is possible to validate the origin of an address that
is injected in a DAO. This specification makes a first step in that
direction by allowing the Root to challenge the RUL by the 6LR that
serves it.
This specification has no requirement on IANA. 12. IANA Considerations
12. Acknowledgments 12.1. RPL Target Option Flags
The author wishes to thank Michael Richardson and Georgios Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL
Papadopoulos for their early reviews of and contributions to this Target Option Flags field. This specification reduces the field to 4
document bits. The IANA is requested to reduce the size of the registry
accordingly.
13. References 12.2. New Subsubregistry for the Status values of the RPL DAO-ACK
Message
13.1. Normative References This specification creates a new subsubregistry for the Status values
of the RPL DAO-ACK Message, under the ICMPv6 parameters registry.
o Possible values are 8-bit unsigned integers (0..255).
o Registration procedure is "Standards Action" [RFC8126].
o Initial allocation is as indicated in Table 1:
+---------+--------------------------------------+----------------+
| Value | Meaning | Defining Spec |
+---------+--------------------------------------+----------------+
| 0 | Unqualified acceptance | RFC6550 |
| | | |
| 1-127 | Reserved for Warning Codes | RFC6550 |
| | | |
| 128 | Duplicate Address | This RFC |
| | | |
| 129 | Out of Storage | This RFC |
| | | |
| 130 | Moved | This RFC |
| | | |
| 131 | Removed | This RFC |
| | | |
| 132 | Validation Requested | This RFC |
| | | |
| 133 | Duplicate Source Address | This RFC |
| | | |
| 134 | Invalid Source Address | This RFC |
| | | |
| 135 | Address topologically incorrect | This RFC |
| | | |
| 136 | 6LBR Registry saturated | This RFC |
| | | |
| 137 | Validation Failed | This RFC |
| | | |
| 138-192 | Reserved for 6LoWPAN ND code mapping | This RFC |
| | | |
| 193-255 | Reserved for other Rejection Codes | RFC6550 |
+---------+--------------------------------------+----------------+
Table 1: Status values of the RPL DAO-ACK Message
13. Acknowledgments
The authors wish to thank Georgios Papadopoulos for their early
reviews of and contributions to this document
14. References
14.1. Normative References
[I-D.ietf-6lo-ap-nd]
Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
"Address Protected Neighbor Discovery for Low-power and
Lossy Networks", draft-ietf-6lo-ap-nd-12 (work in
progress), April 2019.
[I-D.ietf-roll-efficient-npdao]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", draft-ietf-roll-efficient-npdao-15
(work in progress), July 2019.
[I-D.ietf-roll-useofrplinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPL
Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", draft-ietf-
roll-useofrplinfo-31 (work in progress), August 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, Listener Discovery (MLD) for IPv6", RFC 2710,
DOI 10.17487/RFC2710, October 1999, DOI 10.17487/RFC2710, October 1999,
<https://www.rfc-editor.org/info/rfc2710>. <https://www.rfc-editor.org/info/rfc2710>.
skipping to change at page 18, line 46 skipping to change at page 25, line 23
Wireless Personal Area Network (6LoWPAN) Routing", Wireless Personal Area Network (6LoWPAN) Routing",
RFC 6606, DOI 10.17487/RFC6606, May 2012, RFC 6606, DOI 10.17487/RFC6606, May 2012,
<https://www.rfc-editor.org/info/rfc6606>. <https://www.rfc-editor.org/info/rfc6606>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012, RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
Perkins, "Registration Extensions for IPv6 over Low-Power Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
13.2. Informative References 14.2. Informative References
[I-D.ietf-roll-efficient-npdao]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", draft-ietf-roll-efficient-npdao-14
(work in progress), July 2019.
[I-D.ietf-roll-useofrplinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPL
Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", draft-ietf-
roll-useofrplinfo-30 (work in progress), June 2019.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <https://www.rfc-editor.org/info/rfc3315>. 2003, <https://www.rfc-editor.org/info/rfc3315>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
skipping to change at page 20, line 10 skipping to change at page 26, line 30
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <https://www.rfc-editor.org/info/rfc7102>. 2014, <https://www.rfc-editor.org/info/rfc7102>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
and M. Richardson, Ed., "A Security Threat Analysis for
the Routing Protocol for Low-Power and Lossy Networks
(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
<https://www.rfc-editor.org/info/rfc7416>.
[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch", Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016, RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>. <https://www.rfc-editor.org/info/rfc8025>.
[RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
January 2019, <https://www.rfc-editor.org/info/rfc8504>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 6 illustrates the case in Storing mode where the packet is Figure 8 illustrates the case in Storing mode where the packet is
received from the Internet, then the root encapsulates the packet to received from the Internet, then the Root encapsulates the packet to
insert the RPI and deliver to the 6LR that is the parent and last hop insert the RPI and deliver to the 6LR that is the parent and last hop
to the final destination, which is not known to support [RFC8138]. to the final destination, which is not known to support [RFC8138].
The difference with the format presented in Figure 19 of [RFC8138] is The difference with the format presented in Figure 19 of [RFC8138] is
the addition of a SRH-6LoRH before the RPI-6LoRH to transpotr the the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
destination address of the outer IPv6 header. destination address of the outer IPv6 header.
+-+ ... -+-+ ... +-+- ... -+-+- ... +-+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|11110001|SRH-6LoRH| RPI- | IP-in-IP | NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
+-+ ... -+-+ ... +-+- ... -+-+-- ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4bytes-> <- RFC 6282 -> <-4bytes-> <- RFC 6282 ->
No RPL artifact No RPL artifact
Figure 6: Encapsulation to Parent in Storing Mode Figure 8: Encapsulation to Parent 6LR in Storing Mode
In Figure 6, the source of the IP-in-IP encapsulation is the Root, so In Figure 8, the source of the IP-in-IP encapsulation is the Root, so
it is elided in the IP-in-IP 6LoRH. The destination is the parent it is elided in the IP-in-IP 6LoRH. The destination is the parent
6LR of the destination of the inner packet so it cannot be elided. 6LR of the destination of the inner packet so it cannot be elided.
In Storing Mode, it is placed as the single entry in an SRH-6LoRH as In Storing Mode, it is placed as the single entry in an SRH-6LoRH as
the first 6LoRH. Since there is a single entry so the SRH-6LoRH Size the first 6LoRH. Since there is a single entry so the SRH-6LoRH Size
is 0. In this particular example, the 6LR address can be compressed is 0. In this particular example, the 6LR address can be compressed
to 2 bytes so a Type of 1 is used. It results that the total length to 2 bytes so a Type of 1 is used. It results that the total length
of the SRH-6LoRH is 4 bytes. of the SRH-6LoRH is 4 bytes.
In Non-Storing Mode, the encapsulation from the root would be similar In Non-Storing Mode, the encapsulation from the Root would be similar
to that represented in Figure 6 with possibly more hops in the SRH- to that represented in Figure 8 with possibly more hops in the SRH-
6LoRH and possibly multiple SRH-6LoRHs if the various addresses in 6LoRH and possibly multiple SRH-6LoRHs if the various addresses in
the routing header are not compressed to the same format. Note that the routing header are not compressed to the same format. Note that
on the last hop to the parent 6LR, the RH3 is consumed and removed on the last hop to the parent 6LR, the RH3 is consumed and removed
from the compressed form, so the use of Non-Storing Mode vs. Storing from the compressed form, so the use of Non-Storing Mode vs. Storing
Mode is indistinguishable from the packet format. Mode is indistinguishable from the packet format.
Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP
6LoRH is removed, all the router headers that precede it are also 6LoRH is removed, all the router headers that precede it are also
removed. removed.
The Paging Dispatch [RFC8025] may also be removed if there was no The Paging Dispatch [RFC8025] may also be removed if there was no
previous Page change to a Page other than 0 or 1, since the previous Page change to a Page other than 0 or 1, since the
LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and
in Page 1. The resulting packet to the destination is the inner in Page 1. The resulting packet to the destination is the inner
packet compressed with [RFC6282]. packet compressed with [RFC6282].
Author's Address Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
MOUGINS - Sophia Antipolis 06254 MOUGINS - Sophia Antipolis 06254
FRANCE FRANCE
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Michael C. Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/
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