draft-ietf-roll-unaware-leaves-13.txt   draft-ietf-roll-unaware-leaves-14.txt 
ROLL P. Thubert, Ed. ROLL P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6550, 8505 (if approved) M. Richardson Updates: 6550, 8505 (if approved) M. Richardson
Intended status: Standards Track Sandelman Intended status: Standards Track Sandelman
Expires: 18 September 2020 17 March 2020 Expires: 13 October 2020 11 April 2020
Routing for RPL Leaves Routing for RPL Leaves
draft-ietf-roll-unaware-leaves-13 draft-ietf-roll-unaware-leaves-14
Abstract Abstract
This specification extends RFC6550 and RFC8505 to provide routing This specification extends RFC6550 and RFC8505 to provide routing
services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND services to Hosts called RPL Unaware Leaves that implement 6LoWPAN ND
but do not participate to RPL. This specification also enables the but do not participate to RPL. This specification also enables the
RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG. RPL Root to proxy the 6LoWPAN keep-alive flows in its DODAG.
Status of This Memo Status of This Memo
skipping to change at page 1, line 34 skipping to change at page 1, line 34
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 18 September 2020. This Internet-Draft will expire on 13 October 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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 (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 2, line 33 skipping to change at page 2, line 33
6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11 6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 11
6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12 6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 12
6.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13 6.2.1. Support of IPv6 Encapsulation . . . . . . . . . . . . 13
6.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13 6.2.2. Support of the HbH Header . . . . . . . . . . . . . . 13
6.2.3. Support of the Routing Header . . . . . . . . . . . . 13 6.2.3. Support of the Routing Header . . . . . . . . . . . . 13
7. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13 7. Updated RPL Status . . . . . . . . . . . . . . . . . . . . . 13
8. Updated RPL Target option . . . . . . . . . . . . . . . . . . 14 8. Updated RPL Target option . . . . . . . . . . . . . . . . . . 14
9. Protocol Operations for Unicast Addresses . . . . . . . . . . 15 9. Protocol Operations for Unicast Addresses . . . . . . . . . . 15
9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 15 9.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 15
9.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 16 9.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 16
9.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 18 9.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 19
9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 19 9.2. Detailed Operation . . . . . . . . . . . . . . . . . . . 21
9.2.1. By the RUL Acting as 6LN . . . . . . . . . . . . . . 19 9.2.1. By the RUL Acting as 6LN . . . . . . . . . . . . . . 21
9.2.2. By the RPL Border Router Acting as 6LR . . . . . . . 20 9.2.2. By the RPL Border Router Acting as 6LR . . . . . . . 22
9.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 22 9.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 24
9.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 23 9.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 25
10. Protocol Operations for Multicast Addresses . . . . . . . . . 24 10. Protocol Operations for Multicast Addresses . . . . . . . . . 26
11. Security Considerations . . . . . . . . . . . . . . . . . . . 26 11. Security Considerations . . . . . . . . . . . . . . . . . . . 27
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
12.1. Resizing the ARO Status values . . . . . . . . . . . . . 26 12.1. Resizing the ARO Status values . . . . . . . . . . . . . 28
12.2. New DODAG Configuration Option Flag . . . . . . . . . . 27 12.2. New DODAG Configuration Option Flag . . . . . . . . . . 28
12.3. RPL Target Option Flags . . . . . . . . . . . . . . . . 27 12.3. RPL Target Option Flags . . . . . . . . . . . . . . . . 29
12.4. New Subregistry for the RPL Non-Rejection Status 12.4. New Subregistry for the RPL Non-Rejection Status
values . . . . . . . . . . . . . . . . . . . . . . . . . 27 values . . . . . . . . . . . . . . . . . . . . . . . . . 29
12.5. New Subregistry for the RPL Rejection Status values . . 27 12.5. New Subregistry for the RPL Rejection Status values . . 29
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 13. acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
14. Normative References . . . . . . . . . . . . . . . . . . . . 28 14. Normative References . . . . . . . . . . . . . . . . . . . . 30
15. Informative References . . . . . . . . . . . . . . . . . . . 30 15. Informative References . . . . . . . . . . . . . . . . . . . 32
Appendix A. Example Compression . . . . . . . . . . . . . . . . 31 Appendix A. Example Compression . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
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
skipping to change at page 3, line 45 skipping to change at page 3, line 45
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 the routes proactively, but may only fix lazy control that creates the routes proactively, but may only fix
them reactively, upon actual traffic. The result is that RPL them reactively, upon actual traffic. The result is that RPL
provides reachability for most of the LLN nodes, most of the time, provides reachability for most of the LLN nodes, most of the time,
but may not converge in the classical sense. but may not converge in the classical sense.
[RFC6550] provides unicast and multicast routing services to RPL- [RFC6550] provides unicast and multicast routing services to RPL-
Aware nodes (RANs), either as a collection tree or with routing back. Aware nodes (RANs), either as a collection tree or with routing back.
In the latter case, a RAN injects routes to itself using Destination In the latter case, an RAN injects routes to itself using Destination
Advertisement Object (DAO) messages sent either to parent-nodes, in Advertisement Object (DAO) messages sent either to parent-nodes, in
the RPL Storing Mode, or to the Root indicating their parent, in the the RPL Storing Mode, or to the Root indicating their parent, in the
Non-Storing Mode. This process effectively forms a DODAG back to the Non-Storing Mode. This process effectively forms a DODAG back to the
device that is a subset of the DODAG to the Root with all links device that is a subset of the DODAG to the Root with all links
reversed. reversed.
RPL can be deployed as an extension to IPv6 Neighbor Discovery (ND) RPL can be deployed as an extension to IPv6 Neighbor Discovery (ND)
[RFC4861][RFC4862] and 6LoWPAN ND [RFC6775][RFC8505] to maintain [RFC4861][RFC4862] and 6LoWPAN ND [RFC6775][RFC8505] to maintain
reachability within a Non-Broadcast Multi-Access (NBMA) subnet. In reachability within a Non-Broadcast Multi-Access (NBMA) subnet. In
that mode, some nodes may act as Routers and participate to the that mode, some nodes may act as Routers and participate to the
forwarding operations whereas others will only terminate packets, forwarding operations whereas others will only terminate packets,
acting as Hosts in the data-plane. In [RFC6550] terms, a Host that acting as Hosts in the data-plane. In [RFC6550] terms, a Host that
is reachable over the RPL network is called a Leaf. is reachable over the RPL network is called a Leaf.
"When to use RFC 6553, 6554 and IPv6-in-IPv6" [USEofRPLinfo] "When to use RFC 6553, 6554 and IPv6-in-IPv6" [USEofRPLinfo]
introduces the term RPL-Aware-Leaf (RAL) for a Leaf that injects introduces the term RPL-Aware-Leaf (RAL) for a Leaf that injects
routes in RPL to manage the reachability of its own IPv6 addresses. routes in RPL to manage the reachability of its own IPv6 addresses.
In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf that In contrast, the term RPL-Unaware Leaf (RUL) designates a Leaf that
does not participate to RPL at all. RULs may be unable to does not participate to RPL at all. A RUL is an IPv6 Host [RFC8504]
participate because they are very energy constrained. that needs a RPL-Aware Router to obtain routing services over the RPL
network.
A RUL is an IPv6 Host [RFC8504] that needs a RPL-Aware Router to
obtain routing services over the RPL network. The Non-Storing Mode
mechanisms are used to extend the routing state with connectivity to
RULs even when the DODAG is operated in Storing-Mode DODAGs.
This specification leverages the Address Registration mechanism This specification leverages the Address Registration mechanism
defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to defined in 6LoWPAN ND to enable a RUL as a 6LoWPAN Node (6LN) to
interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) to interface with a RPL-Aware Router as a 6LoWPAN Router (6LR) to
request that the 6LR injects the relevant routing information for the request that the 6LR injects the relevant routing information for the
Registered Address in the RPL domain on its behalf. The unicast Registered Address in the RPL domain on its behalf. A RUL may be
packet forwarding operation by the 6LR serving a 6LN that is a RPL unable to participate because it is very energy-constrained, or
Leaf is described in [USEofRPLinfo]. because it is unsafe to let it inject routes in RPL, in which case
using 6LowPAN ND as the interface for the RUL limits the surface of
the possible attacks and optionally protects the address ownership.
The Non-Storing Mode mechanisms are used to extend the routing state
with connectivity to RULs even when the DODAG is operated in Storing-
Mode DODAGs. The unicast packet forwarding operation by the 6LR
serving a 6LN that is a RPL Leaf is described in [USEofRPLinfo].
Examples of routing-agnostic 6LNs include lightly-powered sensors Examples of routing-agnostic 6LNs include lightly-powered sensors
such as window smash sensor (alarm system), and kinetically powered such as window smash sensor (alarm system), and kinetically powered
light switches. Other applications of this specification may include light switches. Other applications of this specification may include
a smart grid network that controls appliances - such as washing a smart grid network that controls appliances - such as washing
machines or the heating system - in the home. Appliances may not machines or the heating system - in the home. Appliances may not
participate to the RPL protocol operated in the Smartgrid network but participate to the RPL protocol operated in the Smartgrid network but
can still interact with the Smartgrid for control and/or metering. can still interact with the Smartgrid for control and/or metering.
2. Terminology 2. Terminology
skipping to change at page 5, line 26 skipping to change at page 5, line 26
information that RPL defines to be placed in data packets, e.g., as information that RPL defines to be placed in data packets, e.g., as
the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By
extension the term "RPI" is often used to refer to the RPL Option extension the term "RPI" is often used to refer to the RPL Option
itself. The DODAG Information Solicitation (DIS), Destination itself. The DODAG Information Solicitation (DIS), Destination
Advertisement Object (DAO) and DODAG Information Object (DIO) Advertisement Object (DAO) and DODAG Information Object (DIO)
messages are also specified in [RFC6550]. The Destination Cleanup messages are also specified in [RFC6550]. The Destination Cleanup
Object (DCO) message is defined in [EFFICIENT-NPDAO]. Object (DCO) message is defined in [EFFICIENT-NPDAO].
This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware
Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node Leaf (RAL) consistently with [USEofRPLinfo]. The term RPL-Aware Node
(RAN) is introduced to refer to a node that is either a RAL or a RPL (RAN) is introduced to refer to a node that is either an RAL or a RPL
Router. As opposed to a RUL, a RAN manages the reachability of its Router. As opposed to a RUL, an RAN manages the reachability of its
addresses and prefixes by injecting them in RPL by itself. addresses and prefixes by injecting them in RPL by itself.
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:
Classical IPv6 ND: "Neighbor Discovery for IP version 6" [RFC4861] Classical IPv6 ND: "Neighbor Discovery for IP version 6" [RFC4861]
and "IPv6 Stateless Address Autoconfiguration" [RFC4862], and "IPv6 Stateless Address Autoconfiguration" [RFC4862],
6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power 6LoWPAN: "Problem Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606] and Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606] and
skipping to change at page 8, line 11 skipping to change at page 8, line 11
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Option Format Figure 1: EARO Option Format
3.2.1. R Flag 3.2.1. R Flag
[RFC8505] introduces the "R" flag in the EARO. The Registering Node [RFC8505] introduces the "R" flag in the EARO. The Registering Node
sets the "R" flag to indicate whether the 6LR should ensure sets the "R" flag to indicate whether the 6LR should ensure
reachability for the Registered Address. If the "R" flag is not set, reachability for the Registered Address. If the "R" flag is not set,
then the Registering Node handles the reachability of the Registered then the Registering Node handles the reachability of the Registered
Address by other means, which means in a RPL network that it is a RAN Address by other means, which means in a RPL network that it is an
or that it uses another RPL Router for reachability services. RAN or that it uses another RPL Router for reachability services.
This document specifies how the "R" flag is used in the context of This document specifies how the "R" flag is used in the context of
RPL. A 6LN is a RUL that requires reachability services for an IPv6 RPL. A 6LN is a RUL that requires reachability services for an IPv6
address iff it sets the "R" flag in the EARO used to register the address if and only if it sets the "R" flag in the NS(EARO) used to
address to a RPL router. Conversely, this document specifies the register the address to a RPL border router acting as 6LR. Upon
behavior of a RPL Router acting as 6LR depending on the setting of receiving the NS(EARO), the RPL router generates a DAO message for
the "R" flag in the EARO. The RPL Router generates a DAO message for the Registered Address if and only if the "R" flag is set.
the Registered Address upon an NS(EARO) iff the "R" flag is set.
3.2.2. TID, I Field and Opaque Fields 3.2.2. TID, I Field and Opaque Fields
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. This is the reason why the support of [RFC8505] 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 by the RUL as opposed to only [RFC6775] is a prerequisite for this
specification (more in Section 6.1). The EARO also transports an specification (more in Section 6.1). The EARO also transports an
Opaque field and an "I" field that describes what the Opaque field Opaque field and an "I" field that describes what the Opaque field
transports and how to use it. Section 9.2.1 specifies the use of the transports and how to use it. Section 9.2.1 specifies the use of the
skipping to change at page 9, line 9 skipping to change at page 9, line 9
This specification does not address how the protection by [AP-ND] This specification does not address how the protection by [AP-ND]
could be extended to RPL. On the other hand, it adds the ROVR to the could be extended to RPL. On the other hand, it adds the ROVR to the
DAO to build the proxied EDAR at the Root (see Section 8), which DAO to build the proxied EDAR at the Root (see Section 8), which
means that nodes that are aware of the Host route to the 6LN are made means that nodes that are aware of the Host route to the 6LN are made
aware of the associated ROVR as well. aware of the associated ROVR as well.
3.3. RFC 8505 Extended DAR/DAC 3.3. RFC 8505 Extended DAR/DAC
[RFC8505] updates the periodic DAR/DAC exchange that takes place [RFC8505] updates the periodic DAR/DAC exchange that takes place
between the 6LR and the 6LBR using Extended DAR/DAC messages which between the 6LR and the 6LBR using Extended DAR/DAC messages which
can carry a ROVR field of variable size. The periodic EDAR/EDAC can carry a ROVR field of variable size. The exchange is triggered
exchange is triggered by a NS(EARO) message and is intended to by an NS(EARO) message and is intended to create, refresh and delete
create, refresh and delete the corresponding state in the 6LBR for a the corresponding state in the 6LBR for a lifetime that is indicated
lifetime that is indicated by the 6LN. by the 6LN. It is protected by the ARQ mechanism specified in 8.2.6
of [RFC6775], though in an LLN, a duration longer than the
RETRANS_TIMER [RFC4861] of 1 second may be necessary to cover the
Turn Around Trip delay from the 6LR to the 6LBR.
Conversely, RPL [RFC6550] specifies a periodic DAO from the 6LN all RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to
the way to the Root that maintains the routing state in the RPL the Root that maintains the routing state in the RPL network for the
network for the lifetime indicated by the source of the DAO. This lifetime indicated by the source of the DAO. This means that for
means that for each address, there are two keep-alive messages that each address, there are two keep-alive messages that traverse the
traverse the whole network, one to the Root and one to the 6LBR. whole network, one to the Root and one to the 6LBR.
This specification removes the extraneous keep-alive across the LLN. This specification removes the extraneous keep-alive across the LLN.
The 6LR turns the periodic Address Registration from the RUL into a The 6LR turns the periodic Address Registration from the RUL into a
DAO message to the Root on every refresh, but it only generates the DAO message to the Root on every refresh, but it only generates the
EDAR upon the first registration, for the purpose of DAD. Upon a EDAR upon the first registration, for the purpose of DAD. Upon a
refresher DAO, the Root proxies the EDAR exchange to refresh the refresher DAO, the Root proxies the EDAR exchange to refresh the
state at the 6LBR on behalf of the 6LR, as illustrated in Figure 7. state at the 6LBR on behalf of the 6LR, as illustrated in Figure 7.
3.3.1. RFC 7400 Capability Indication Option 3.3.1. RFC 7400 Capability Indication Option
skipping to change at page 9, line 36 skipping to change at page 9, line 39
3.3.1. RFC 7400 Capability Indication Option 3.3.1. RFC 7400 Capability Indication Option
"6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power "6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the
6LoWPAN Capability Indication Option (6CIO) that enables a node to 6LoWPAN Capability Indication Option (6CIO) that enables a node to
expose its capabilities in Router Advertisement (RA) messages. expose its capabilities in Router Advertisement (RA) messages.
[RFC8505] defines a number of bits in the 6CIO, in particular: [RFC8505] defines a number of bits in the 6CIO, in particular:
L: Node is a 6LR. L: Node is a 6LR.
E: Node is an IPv6 ND Registrar -- i.e., it supports registrations E: Node is an IPv6 ND Registrar -- i.e., it supports registrations
based on EARO. based on EARO.
P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that P: Node is a Routing Registrar, -- i.e., an IPv6 ND Registrar that
also provides reachability services for the Registered Addres also provides reachability services for the Registered Address.
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 | Length = 1 | Reserved |D|L|B|P|E|G| | Type | Length = 1 | Reserved |D|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: 6CIO flags Figure 2: 6CIO flags
skipping to change at page 11, line 44 skipping to change at page 11, line 44
[RFC8505] and set the "R" flag in the EARO. The RUL SHOULD support [RFC8505] and set the "R" flag in the EARO. The RUL SHOULD support
[AP-ND] and use it to protect the ownership of its addresses. The [AP-ND] and use it to protect the ownership of its addresses. The
RUL MUST NOT request routing services from a 6LR that does not RUL MUST NOT request routing services from a 6LR that does not
originate RA messages with a CIO that has the L, P, and E flags all originate RA messages with a CIO that has the L, P, and E flags all
set as discussed in Section 3.3.1. set as discussed in Section 3.3.1.
A RUL that has multiple potential routers MUST prefer those that A RUL that has multiple potential routers MUST prefer those that
provide routing services. The RUL MUST register to all the 6LRs from provide routing services. The RUL MUST register to all the 6LRs from
which it desires routing services. If there are no available which it desires routing services. If there are no available
routers, the connection of the RUL fails. The Address Registrations routers, the connection of the RUL fails. The Address Registrations
SHOULD be performed in a rapid sequence, using the exact same EARO SHOULD be performed in an RApid sequence, using the exact same EARO
for a same Address. Gaps between the Address Registrations will for a same Address. Gaps between the Address Registrations will
invalidate some of the routes till the Address Registration finally invalidate some of the routes till the Address Registration finally
shows on those routes as well. shows on those routes as well.
[RFC8505] introduces error Status values in the NA(EARO) which can be [RFC8505] introduces error Status values in the NA(EARO) which can be
received synchronously upon an NS(EARO) or asynchronously. The RUL received synchronously upon an NS(EARO) or asynchronously. The RUL
MUST support both cases and MUST refrain from using the address when MUST support both cases and MUST refrain from using the address when
the Status value indicates a rejection. the Status value indicates a rejection.
6.2. External Routes and RPL Artifacts 6.2. External Routes and RPL Artifacts
skipping to change at page 12, line 38 skipping to change at page 12, line 38
its packets with an RPI, the 6LR needs to tunnel them to the Root to its packets with an RPI, the 6LR needs to tunnel them to the Root to
add the RPI. As a rule of a thumb and except for the very special add the RPI. As a rule of a thumb and except for the very special
case above, the packets from and to a RUL are always encapsulated case above, the packets from and to a RUL are always encapsulated
using an IP-in-IP tunnel between the Root and the 6LR that serves the using an IP-in-IP tunnel between the Root and the 6LR that serves the
RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4, RUL (see sections 7.1.4, 7.2.3, 7.2.4, 7.3.3, 7.3.4, 8.1.3, 8.1.4,
8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details). 8.2.3, 8.2.4, 8.3.3 and 8.3.4 of [USEofRPLinfo] for details).
In Non-Storing Mode, packets going down carry a Source Routing Header In Non-Storing Mode, packets going down carry a Source Routing Header
(SRH). The IP-in-IP encapsulation, the RPI and the SRH are (SRH). The IP-in-IP encapsulation, the RPI and the SRH are
collectively called the "RPL artifacts" and can be compressed using collectively called the "RPL artifacts" and can be compressed using
[RFC8138]. Figure 12 presents an example compressed format for a [RFC8138]. Figure 14 presents an example compressed format for a
packet forwarded by the Root to a RUL in a Storing Mode DODAG. packet forwarded by the Root to a RUL in a Storing Mode DODAG.
The inner packet that is forwarded to the RUL may carry some RPL The inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it artifacts, e.g., an RPI if the original packet was generated with it
and possibly an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo] and possibly an SRH in a Non-Storing Mode DODAG. [USEofRPLinfo]
expects the RUL to support the basic "IPv6 Node Requirements" expects the RUL to support the basic "IPv6 Node Requirements"
[RFC8504]. In particular the RUL is expected to ignore the RPL [RFC8504]. In particular the RUL is expected to ignore the RPL
artifacts that are either consumed or not applicable to a Host. artifacts that are either consumed or not applicable to a Host.
A RUL is not expected to support the compression method defined in A RUL is not expected to support the compression method defined in
skipping to change at page 15, line 46 skipping to change at page 15, line 46
The description below assumes that the Root sets the "P" flag in the The description below assumes that the Root sets the "P" flag in the
DODAG Configuration Option and performs the EDAR proxy operation. DODAG Configuration Option and performs the EDAR proxy operation.
9.1. General Flow 9.1. General Flow
This specification eliminates the need to exchange keep-alive This specification eliminates the need to exchange keep-alive
Extended Duplicate Address messages, EDAR and EDAC, all the way from Extended Duplicate Address messages, EDAR and EDAC, all the way from
a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange a 6LN to the 6LBR across a RPL mesh. Instead, the EDAR/EDAC exchange
with the 6LBR is proxied by the RPL Root upon a DAO message that with the 6LBR is proxied by the RPL Root upon a DAO message that
refreshes the RPL routing state. refreshes the RPL routing state. Any combination of the logical
functions of 6LR, Root and 6LBR might be collapsed in a single node.
To achieve this, the lifetimes and sequence counters in 6LoWPAN ND To achieve this, the lifetimes and sequence counters in 6LoWPAN ND
and RPL are aligned. In other words, the Path Sequence and the Path and RPL are aligned. In other words, the Path Sequence and the Path
Lifetime in the DAO message are taken from the Transaction ID and the Lifetime in the DAO message are taken from the Transaction ID and the
Address Registration lifetime in the NS(EARO) message from the 6LN. Address Registration lifetime in the NS(EARO) message from the 6LN.
The proxy operation applies to both RULs and RANs. In a RPL network The proxy operation applies to both RULs and RANs. In a RPL network
where the function is enabled, refreshing the state in the 6LBR is where the function is enabled, refreshing the state in the 6LBR is
the responsibility of the Root. Consequently, only addresses that the responsibility of the Root. Consequently, only addresses that
are injected in RPL will be kept alive by the RPL Root. are injected in RPL will be kept alive by the RPL Root. In a same
fashion, if an additional routing protocol is deployed on a same
In a same fashion, if an additional routing protocol is deployed on a network, that additional routing protocol may need to handle the keep
same network, that additional routing protocol may need to handle the alive procedure for the addresses that it serves.
keep alive procedure for the addresses that it serves.
On the first Address Registration, illustrated in Figure 5 and On the first Address Registration, illustrated in Figure 5 for RPL
Figure 8 for RPL Non-Storing and Storing Mode respectively, the Non-Storing Mode, the Extended Duplicate Address exchange takes place
Extended Duplicate Address exchange takes place as prescribed by as prescribed by [RFC8505]. If the exchange fails, the 6LR returns
[RFC8505]. Any of the functions 6LR, Root and 6LBR might be an NA message with a negative status to the 6LN, the NCE is not
collapsed in a single node. created and the address is not injected in RPL. If it is successful,
the 6LR creates an NCE and injects the Registered Address in RPL
using DAO/DAO-ACK exchanges all the way to the RPL DODAG Root.
When successful, the flow creates a Neighbor Cache Entry (NCE) in the The 6LN signals the termination of a registration with a 6LR using an
6LR, and the 6LR injects the Registered Address in RPL using DAO/DAO- NS(EARO) with a Registration Lifetime set to 0. If the 6LR does not
ACK exchanges all the way to the RPL DODAG Root. The protocol does use the ROVR in the RPL Target Option then it MUST perform an EDAR/
not carry a specific information that the Extended Duplicate Address EDAC exchange to cleanup the state at the 6LBR, as illustrated in
messages were already exchanged, so the Root proxies them anyway.
9.1.1. In RPL Non-Storing-Mode 9.1.1. In RPL Non-Storing-Mode
In Non-Storing Mode, the DAO message flow can be nested within the In Non-Storing Mode, the DAO message flow can be nested within the
Address Registration flow as illustrated in Figure 5. Address Registration flow as illustrated in Figure 5.
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
skipping to change at page 18, line 12 skipping to change at page 18, line 12
using a RPL Status with the 'A' flag set that imbeds a 6LoWPAN Status using a RPL Status with the 'A' flag set that imbeds a 6LoWPAN Status
value as discussed in Section 7. value as discussed in Section 7.
If the Root could not return the negative Status in the DAO-ACK then If the Root could not return the negative Status in the DAO-ACK then
it sends an asynchronous Destination Cleanup Object (DCO) message it sends an asynchronous Destination Cleanup Object (DCO) message
[EFFICIENT-NPDAO] to the 6LR by placing the negative Status in the [EFFICIENT-NPDAO] to the 6LR by placing the negative Status in the
RPL Status with the 'A' flag set. Note that if both are used in a RPL Status with the 'A' flag set. Note that if both are used in a
short interval of time, the DAO-ACK and DCO messages are not short interval of time, the DAO-ACK and DCO messages are not
guaranteed to arrive in the same order at the 6LR. guaranteed to arrive in the same order at the 6LR.
The 6LR may still receive a requested DAO-ACK even after it received The 6LR may receive a requested DAO-ACK even after it received a DCO,
a DCO, but the negative Status in the DCO supercedes a positive but the negative Status in the DCO supercedes a positive Status in
Status in the DAO-ACK regardless of the order in which they are the DAO-ACK regardless of the order in which they are received. Upon
received. Upon the DAO-ACK - or the DCO if it arrives first - the the DAO-ACK - or the DCO if it arrives first - the 6LR responds to
6LR responds to the RUL with a NA(EARO). If the RPL Status has the the RUL with an NA(EARO). If the RPL Status has the 'A' flag set,
'A' flag set, then the ND Status is extracted and passed in the EARO; then the ND Status is extracted and passed in the EARO; else, if the
else, if the 'E' flag is set, indicating a rejection, then the status 'E' flag is set, indicating a rejection, then the status 4 "Removed"
4 "Removed" is used; else, the ND Status of 0 indicating "Success" is is used; else, the ND Status of 0 indicating "Success" is used.
used.
The RUL may terminate the registration at anytime by using a
Registration Lifetime of 0. This specification expects that the RPL
Target option transports a ROVR. If that is the case, the normal
heartbeat flow is sufficient to inform the 6LBR using the Root as
proxy as illustrated in Figure 7. If the 6LR could not add the ROVR
to the DAO message, then it MUST inform the 6LBR separately using as
illustrated in Figure 8.
6LN/RUL 6LR Root 6LBR
| | | |
|NS(EARO,Lifet=0)| | |
|--------------->| |
| | Extended DAR |
| |--------------------------------->|
| | |
| | Extended DAC |
| |<---------------------------------|
| |DAO (Lifeti=0)| |
| |------------->| |
| | | anonymous EDAR |
| | |------------------>|
| | | EDAC |
| | |<------------------|
| | DAO-ACK | |
| |<-------------| |
| NA(EARO) | | |
|<---------------| | |
| | | |
| <Remove NCE> | |
| | | |
Figure 8: Last Registration Flow in Non-Storing Mode, No ROVR
9.1.2. In RPL Storing-Mode 9.1.2. In RPL Storing-Mode
In RPL Storing Mode, the DAO-ACK is optional. When it is used, it is In RPL 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 generated by the RPL parent, which does not need to wait for the
grand-parent to send the acknowledgement. A successful DAO-ACK is grand-parent to send the acknowledgment. A successful DAO-ACK is not
not a guarantee that the DAO has yet reached the Root or that the a guarantee that the DAO has yet reached the Root or that the EDAR
EDAR has succeeded. was successfully proxied by the Root.
The 6LR uses the EDAR/EDAC exchange as in Non-Storing Mode, for the
initial registration, and also possibly at the termination in the
case the 6LR could not add the ROVR to the RPL Target option of the
DAO message.
6LN/RUL 6LR 6LR Root 6LBR 6LN/RUL 6LR 6LR Root 6LBR
| | | | | | | | | |
| NS(EARO) | | | | | NS(EARO) | | | |
|-------------->| | | | |-------------->| | | |
| | Extended DAR |
| |------------------------------------------------->|
| | |
| | Extended DAC |
| |<-------------------------------------------------|
| NA(EARO) | | | | | NA(EARO) | | | |
|<--------------| | | | |<--------------| | | |
| | | | |
| | DAO | | | | | DAO | | |
| |-------------->| | | | |-------------->| | |
| | DAO-ACK | | | | | DAO-ACK | | |
| |<--------------| | | | |<--------------| | |
Figure 9: First Registration Flow in Storing Mode
The Storing Mode of RPL does not provide and end-to-end confirmation
that a DAO reached the root. When the 6LR has just joined, and later
if DAO messages are lost before reaching the Root, the 6LR might not
be reachable back from the Root. Performing an EDAR/EDAC exchange on
behalf of a RUL provides that confirmation. On the other hand, if
the 6LR retries an EDAR and never gets and EDAC back, it SHOULD
resend a DAO to become reachable again, before it tries another
sequence of EDAR.
6LN/RUL 6LR 6LR Root 6LBR
| | | | | | | | | |
| NS(EARO) | | | |
|-------------->| | | |
| NA(EARO) | | | |
|<--------------| | | |
| | DAO | | |
| |-------------->| | |
| | DAO-ACK | | |
| |<--------------| | |
| | | DAO | | | | | DAO | |
| | |-------------->| | | | |-------------->| |
| | | DAO-ACK | | | | | DAO-ACK | |
| | |<--------------| | | | |<--------------| |
| | | | |
| | | | (anonymous) EDAR | | | | | (anonymous) EDAR |
| | | |----------------->| | | | |----------------->|
| | | | EDAC(ROVR) | | | | | EDAC(ROVR) |
| | | |<-----------------| | | | |<-----------------|
| | | | | | | | | |
Figure 8: Next Registration Flow in Storing Mode
Figure 10: Next Registration Flow in Storing Mode
If the keep-alive fails, or an asynchronous issue is reported, the If the keep-alive fails, or an asynchronous issue is reported, the
path can be cleaned up asynchronously using a DCO message path can be cleaned up asynchronously using a DCO message
[EFFICIENT-NPDAO] as illustrated in Figure 9 and described in further [EFFICIENT-NPDAO] as illustrated in Figure 11 and described in
details in Section 9.2.3. further details in Section 9.2.3.
6LN/RUL 6LR 6LR Root 6LBR 6LN/RUL 6LR 6LR Root 6LBR
| | | | | | | | | |
| | | | NA(EARO, Status) | | | | | NA(EARO, Status) |
| | | |<-----------------| | | | |<-----------------|
| | | | | | | | | |
| | | DCO(Status) | | | | | DCO(Status) | |
| | |<------------| | | | |<------------| |
| | | | | | | | | |
| | DCO(Status) | | | | | DCO(Status) | | |
| |<------------| | | | |<------------| | |
| | | | | | | | | |
| NA(EARO, Status) | | | | | NA(EARO, Status) | | | |
|<-----------------| | | | |<-----------------| | | |
| | | | | | | | | |
Figure 9: Issue in Storing Mode Figure 11: Issue in Storing Mode
In the case illustrated here, the issue is actually detected in the
ND protocol and reported in the State of a NA(EARO) message. That
statis is transported in the DCO message as a RPL Status with the 'A'
and typically the 'E' flags set.
9.2. Detailed Operation 9.2. Detailed Operation
9.2.1. By the RUL Acting as 6LN 9.2.1. By the RUL Acting as 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, and a RUL is expected to operate as follows: compliant 6LN, and a RUL is expected to operate as follows:
1. The 6LN obtains an IPv6 global address, either using Stateless 1. The 6LN obtains an IPv6 global address, either using Stateless
Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix Address Autoconfiguration (SLAAC) [RFC4862] based on a Prefix
Information Option (PIO) [RFC4861] found in a RA message, or some Information Option (PIO) [RFC4861] found in an RA message, or
other means such as DHCPv6 [RFC3315]. some other means such as DHCPv6 [RFC3315].
2. Once it has formed an address, the 6LN (re)registers its address 2. Once it has formed an address, the 6LN (re)registers its address
periodically, within the Lifetime of the previous Address periodically, within the Lifetime of the previous Address
Registration, as prescribed by [RFC6775] and [RFC8505], to Registration, as prescribed by [RFC6775] and [RFC8505], to
refresh the NCE before the lifetime indicated in the EARO refresh the NCE before the lifetime indicated in the EARO
expires. The TID is incremented each time and wraps in a expires. The TID is incremented each time and wraps in a
lollipop fashion (see section 5.2.1 of [RFC8505] which is fully lollipop fashion (see section 5.2.1 of [RFC8505] which is fully
compatible with section 7.2 of [RFC6550]). compatible with section 7.2 of [RFC6550]).
3. As stated in section 5.2 of [RFC8505], the 6LN can register to 3. As stated in section 5.2 of [RFC8505], the 6LN can register to
more than one 6LR at the same time. In that case, it MUST use more than one 6LR at the same time. In that case, it MUST use
the same value of TID for all of the parallel Address the same value of TID for all of the parallel Address
Registrations. Registrations. The 6LN should send the registration(s) with a
non-zero Registration Lifetime and ensure that one succeeds
before it terminates other registrations to maintain the state in
the network and at the 6LBR and minimize the churn.
4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets 4. Following section 5.1 of [RFC8505], a 6LN acting as a RUL sets
the "R" flag in the EARO of at least one registration, whereas the "R" flag in the EARO of at least one registration, whereas
acting as a RAN it never does. If the "R" flag is not echoed in acting as an RAN it never does. If the "R" flag is not echoed in
the NA, the RUL SHOULD attempt to use another 6LR. the NA, the RUL SHOULD attempt to use another 6LR. The 6LN
should send the registration(s) with the "R" flag set and ensure
that one succeeds before it sends the registrations with the flag
reset. In case of a conflict with the preceeding rule on
lifetime, the rule on lifetime has precedence.
5. The 6LN may use any of the 6LRs to which it registered as default 5. The 6LN may use any of the 6LRs to which it registered as default
gateway. Using a 6LR to which the 6LN is not registered may gateway. Using a 6LR to which the 6LN is not registered may
result in packets dropped at the 6LR by a Source Address result in packets dropped at the 6LR by a Source Address
Validation function (SAVI) so it is not recommended. Validation function (SAVI) so it is not recommended.
Even without support for RPL, a RUL may be aware of opaque values to Even without support for RPL, a RUL may be aware of opaque values to
be provided to the routing protocol. If the RUL has a knowledge of 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 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 set the Opaque field in the EARO to the RPLInstanceID, else it MUST
leave the Opaque field to zero. leave the Opaque field to zero.
Regardless of the setting of the Opaque field, the 6LN MUST set the Regardless of the setting of the Opaque field, the 6LN MUST set the
"I" field to zero to signal "topological information to be passed to "I" field to zero to signal "topological information to be passed to
a routing process" as specified in section 5.1 of [RFC8505]. a routing process" as specified in section 5.1 of [RFC8505].
A RUL is not expected to produce RPL artifacts in the data packets, 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 but it MAY do so. For instance, if the RUL has a minimal awareness
of the RPL Instance then it can build an RPI. A RUL that places an of the RPL Instance then it can build an RPI. A RUL that places an
RPI in a data packet MUST indicate the RPLInstanceID that corresponds RPI in a data packet MUST indicate the RPLInstanceID of the RPL
to the RPL Instance the packet should be injected into. All the Instance where the packet should be forwarded. All the flags and the
flags and the Rank field are set to zero as specified by section 11.2 Rank field are set to zero as specified by section 11.2 of [RFC6550].
of [RFC6550].
9.2.2. By the RPL Border Router Acting as 6LR 9.2.2. By the RPL Border Router Acting as 6LR
Also as prescribed by [RFC8505], the 6LR generates an EDAR message Also as prescribed by [RFC8505], the 6LR generates an EDAR message
upon reception of a valid NS(EARO) message for the Address upon reception of a valid NS(EARO) message for the registration of a
Registration of a new IPv6 Address by a 6LN and for the termination new IPv6 Address by a 6LN. If the initial EDAR/EDAC exchange
of a registration (lifetime of 0). succeeds, then the 6LR installs an NCE for the Registration Lifetime.
For the refreshes of the registration, if the RPL Root has indicated
If the initial EDAR/EDAC exchange succeeds, then the 6LR installs an that it proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see
NCE for the registration lifetime. If the "R" flag 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 the EARO of the
NA message that is sends in response.
From then on, as long as the "R" flag is set in the periodic NS(EARO)
from the 6LN and this Router can still manage the reachability of
Registered Address, the 6LR keeps setting the "R" flag in the EARO of
the response NA message. But if the RPL Root has indicated that it
proxies the keep-alive EDAR/EDAC exchange with the 6LBR (see
Section 4), the 6LR MUST refrain from sending the keep-alive EDAR Section 4), the 6LR MUST refrain from sending the keep-alive EDAR
itself. itself.
If the "R" flag is set in the NS(EARO), the 6LR SHOULD attempt to
inject the host route in RPL, unless this is barred for other
reasons, like a saturation of the network or if its RPL parent. The
"R" flag MUST set in the NA(EARO) back if 6LR successfully injected
the Registered Address in RPL and MUST be reset otherwise.
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 RPI in the packets sourced at the registered address when there is no RPI in the
packet, in which case the 6LR MUST encapsulate the packet to the Root packet, in which case the 6LR MUST encapsulate the packet to the Root
adding an RPI in the outer header. If the Opaque field is zero, the adding an RPI in the outer header. If the Opaque field is zero, the
6LR is free to use the default RPL Instance (zero) for the registered 6LR is free to use the default RPL Instance (zero) for the registered
address or to select an Instance of its choice. address or to select an Instance of its choice.
if the "I" field is not zero, then the 6LR MUST consider that the if the "I" field is not zero, then the 6LR MUST consider that the
Opaque field is zero. If the Opaque field is not zero, then it is Opaque field is zero. If the Opaque field is not zero, then it is
expected to carry a RPLInstanceID for the RPL Instance suggested by expected to carry a RPLInstanceID for the RPL Instance suggested by
the 6LN. If the 6LR does not participate to the associated Instance, the 6LN. If the 6LR does not participate to the associated Instance,
then the 6LR MUST consider that the Opaque field is zero; else, that then the 6LR MUST consider that the Opaque field is zero; else, that
is if the 6LR participates to the suggested Instance, then the 6LR is if the 6LR participates to the suggested Instance, then the 6LR
SHOULD use that Instance for the registered address. SHOULD use that Instance for the registered address.
The DAO message advertising the Registered Address MUST be The DAO message advertising the Registered Address MUST be
constructed as follows: constructed as follows:
1. The Registered Address is placed in an RPL Target Option in the 1. The Registered Address is signaled as Target Prefix in the RPL
DAO message as the Target Prefix, and the Prefix Length is set to Target Option in the DAO message; the Prefix Length is set to 128
128;
2. RPL Non-Storing Mode is to be used. The 6LR indicates one of its 2. RPL Non-Storing Mode is to be used. The 6LR indicates one of its
global or unique-local IPv6 unicast addresses as the Parent global or unique-local IPv6 unicast addresses as the Parent
Address in the associated RPL Transit Information Option (TIO). Address in the associated RPL Transit Information Option (TIO)
3. the External 'E' flag in the TIO is set to indicate that the 6LR 3. the External 'E' flag in the TIO is set to indicate that the 6LR
redistributes an external target into the RPL network. redistributes an external target into the RPL network
4. the Path Lifetime in the TIO is computed from the Lifetime in the 4. the Path Lifetime in the TIO is computed from the Lifetime in the
EARO Option. This adapts it to the Lifetime Units used in the EARO Option. This adapts it to the Lifetime Units used in the
RPL operation. Note that if the lifetime is 0, then the 6LR RPL operation; note that if the lifetime is 0, then the 6LR
generates a No-Path DAO message that cleans up the routes down to generates a No-Path DAO message that cleans up the routes down to
the Address of the 6LN; the Address of the 6LN; this also causes the Root as a proxy to
send an EDAR message to the 6LBR with a Lifetime of 0.
5. the Path Sequence in the TIO is set to the TID value found in the 5. the Path Sequence in the TIO is set to the TID value found in the
EARO option; EARO option.
6. Upon receiving an NS message with an EARO and the "R" flag set, The NCE is removed if the 6LR tries to inject the route is RPL and
the 6LR SHOULD inject the Registered Address in RPL by sending a fails for reasons related to ND, which is recognized by both the 'E'
DAO message on behalf of the 6LN. If the Registration Lifetime and the 'A' flags set in the RPL Status of the DAO-ACK or the DCO, as
was 0, the effect is to remove the route and then the NCE; detailed below.
If for whatever reason the 6LR does not inject the Registered Address Otherwise, success injecting the route is assumed if a DAO-ACK was
in RPL, it MUST send an NA(EARO) back with the appropriate status and not requested or if it is received with a RPL Status that is not a
the "R" flag not set. rejection (i.e., the 'E' flag not set).
If the 6LR injects the Registered Address in RPL and either a DAO-ACK In case of success, if the 'A' flag is set in the RPL Status of the
was not requested or is received with a RPL Status that is not a DAO-ACK, then the 6LR MUST use the Status Value in the RPL Status for
rejection ("E" flag not set), the 6LR MUST install or refresh the NCE the Status in the NA(EARO), else a Status of 0 (Success) is returned.
for the address and reply to the RUL with an NA(EARO) with a Status
of 0 (Success) and the "R" flag set.
In case of a DAO-ACK or a DCO indicating transporting an EARO Status The status of 0 MUST also be used if the 6LR could not even try to
Value of 5 (Validation Requested), a 6LR that supports Address inject the route - note that the "R" flag is reset in that case.
Protected Neighbor Discovery (AP-ND) MUST challenge the 6LN for
ownership of the address, as described in section 6.1 of [AP-ND]. If In a network where Address Protected Neighbor Discovery (AP-ND) is
the challenge succeeds then the operations continue as normal. In enabled, in case of a DAO-ACK or a DCO indicating transporting an
EARO Status Value of 5 (Validation Requested), the 6LR MUST challenge
the 6LN for ownership of the address, as described in section 6.1 of
[AP-ND], before the Registration is complete. This ensures that the
address validated before it is injected in RPL.
If the challenge succeeds then the operations continue as normal. In
particular a DAO message is generated upon the NS(EARO) that proves particular a DAO message is generated upon the NS(EARO) that proves
the ownership of the address. If the challenge failed, the 6LR the ownership of the address. If the challenge failed, the 6LR
rejects the registration as prescribed by AP-ND and may take actions rejects the registration as prescribed by AP-ND and may take actions
to protect itself against DoS attacks by a rogue 6LN, see Section 11. to protect itself against DoS attacks by a rogue 6LN, see Section 11.
If the 6LR does not support AP-ND, it MUST send an NA to the 6LN with
a Status of 0 (Success) and the "R" flag not set.
The other rejection codes indicate that the 6LR failed to inject the The other rejection codes indicate that the 6LR failed to inject the
address into the RPL network. If an EARO Status is transported, the address into the RPL network. If an EARO Status is transported, the
6LR MUST send a NA(EARO) to the RUL with that Status value, and the 6LR MUST send a NA(EARO) to the RUL with that Status value, and the
"R" flag not set. Similarly, upon receiving a DCO message indicating "R" flag not set. Similarly, upon receiving a DCO message indicating
that the address of a RUL should be removed from the routing table, 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 embedded the 6LR issues an asynchronous NA(EARO) to the RUL with the embedded
ND Status value if there was one, and the "R" flag not set. ND Status value if there was one, and the "R" flag not set.
If a 6LR receives a valid NS(EARO) message with the "R" flag reset If a 6LR receives a valid NS(EARO) message with the "R" flag reset
and a Registration Lifetime that is not 0, and the 6LR was and a Registration Lifetime that is not 0, and the 6LR was
redistributing the Registered Address due to previous NS(EARO) redistributing the Registered Address due to previous NS(EARO)
messages with the flag set, then it MUST stop injecting the address. messages with the flag set, then it MUST stop injecting the address.
It is up to the Registering 6LN to maintain the corresponding route It is up to the Registering 6LN to maintain the corresponding route
from then on, either keeping it active via a different 6LR or by from then on, either keeping it active via a different 6LR or by
acting as a RAN and managing its own reachability. acting as an RAN and managing its own reachability.
9.2.3. By the RPL Root 9.2.3. By the RPL Root
A RPL Root SHOULD set the "P" flag in the RPL configuration option of A RPL Root SHOULD set the "P" flag in the RPL configuration option of
the DIO messages that it generates (see Section 4) to signal that it the DIO messages that it generates (see Section 4) to signal that it
proxies the keep-alive EDAR/EDAC echange. The remainder of this proxies the keep-alive EDAR/EDAC echange. The remainder of this
section assumes that it does. section assumes that it does.
Upon reception of a DAO message, for each RPL Target option that Upon reception of a DAO message, for each RPL Target option that
creates or updates an existing RPL state, the Root notifies the 6LBR. creates or updates an existing RPL state, the Root notifies the 6LBR.
skipping to change at page 23, line 35 skipping to change at page 25, line 17
Upon a Status value in an EDAC message that is not "Success", the Upon a Status value in an EDAC message that is not "Success", the
Root SHOULD destroy the formed paths using either a DAO-ACK (in Non- Root SHOULD destroy the formed paths using either a DAO-ACK (in Non-
Storing Mode) or a DCO downwards as specified in [EFFICIENT-NPDAO]. Storing Mode) or a DCO downwards as specified in [EFFICIENT-NPDAO].
Failure to destroy the former path would result in Stale routing Failure to destroy the former path would result in Stale routing
state and local black holes if the address belongs to another party state and local black holes if the address belongs to another party
elsewhere in the network. The RPL Status value that maps the 6LoWPAN elsewhere in the network. The RPL Status value that maps the 6LoWPAN
ND Status value MUST be embedded in the RPL Status in the DCO. ND Status value MUST be embedded in the RPL Status in the DCO.
9.2.4. By the 6LBR 9.2.4. By the 6LBR
Upon reception of an EDAR message with the ROVR field is set to 0 Upon reception of an EDAR message with the ROVR field set to a non-
indicating an anonymous EDAR, the 6LBR checks whether an entry exists zero value, the 6LBR acts as prescribed by [RFC8505]. If the ROVR is
for the address. If the entry does not exist, the 6LBR does not set to 0, indicating an anonymous EDAR, the 6LBR MUST act as below:
create the entry, and answers with a Status "Removed" in the EDAC
message.
If the entry exists, the 6LBR computes whether the TID in the EDAR 1. The 6LBR checks whether an entry exists for the address. If the
message is fresher than the one in the entry as prescribed in section entry does not exist, the 6LBR MUST NOT create the entry, and it
4.2.1. of [RFC8505] and MUST operate as below: MUST answer with a Status "Removed" in the EDAC message. If the
entry exists, the 6LBR computes whether the TID in the EDAR
message is fresher than the one in the entry as prescribed in
section 4.2.1. of [RFC8505], and continues as follows:
1. If the anonymous EDAR message is fresher, the 6LBR updates the 2. If the anonymous EDAR message is fresher, the 6LBR updates the
TID in the entry, restarts the heartbeat timer for the entry, and TID in the entry, restarts the heartbeat timer for the entry, and
answers with a Status "Success" in the EDAC message. If the answers with a Status "Success" in the EDAC message. If the
duration of the lifetime of the entry is extended by the value of the Registration Lifetime is smaller than the value in
Registration Lifetime in the EDAR message, it also updates the the entry, then the latter value MUST be used for the heartbeat;
lifetime of the entry. this means in particular that the Registration Lifetime of 0 is
ignored. Conversely, if the duration of the Lifetime is extended
2. If the TIDs are the same, the 6LBR does not update the entry, and by the Registration Lifetime in the EDAR message, it is used for
answers with a Status "Success" in the EDAC message. the hearbeat and to the value in the entry is updated.
3. If the TID in the entry is fresher, the 6LBR does not update the 3. If the TID in the entry is the same or fresher, the 6LBR does not
entry, and answers with a Status "Moved" in the EDAC message. update the entry, and answers with a Status "Success" and "Moved"
in the EDAC message, respectively.
The EDAC that is constructed is the same as if the anonymous EDAR was The EDAC that is constructed is the same as if the anonymous EDAR was
a full EDAR, and includes the ROVR that is associated to the Address a full EDAR, but for the ROVR that is set to zero.
Registration.
10. Protocol Operations for Multicast Addresses 10. 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 of 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 Address Registration, as illustrated in Figure 10, the On the first Address Registration, as illustrated in Figure 12, the
6LN, as an MLD listener, sends an unsolicited Report to the 6LR in 6LN, as an MLD listener, sends an unsolicited Report to the 6LR in
order to start receiving the flow immediately. order to start receiving the flow immediately.
6LN/RUL 6LR Root 6LBR 6LN/RUL 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 10: First Multicast Registration Flow Figure 12: First Multicast Registration Flow
Since multicast Layer-2 messages are avoided, it is important that Since multicast Layer-2 messages are avoided, it is important that
the asynchronous messages for unsolicited Report and Done are sent the asynchronous messages for unsolicited Report and Done are sent
reliably, for instance using a Layer-2 acknoledgement, or attempted reliably, for instance using a Layer-2 acknowledgment, or attempted
multiple times. 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.
The Root proxies the MLD exchange as a listener with the 6LBR acting The Root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the as the querier, so as to get packets from a source external to the
RPL domain. Upon a DAO with a multicast target, the RPL Root checks RPL domain. Upon a DAO with a multicast target, the RPL Root checks
if it is already registered as a listener for that address, and if if it is already registered as a listener for that address, and if
not, it performs its own unsolicited Report for the multicast target. not, it performs its own unsolicited Report for the multicast target.
An Address re-Registration is pulled periodically by 6LR acting as An Address re-Registration is pulled periodically by 6LR acting as
querier. Note that the message may be sent unicast to all the known querier. Note that the message may be sent unicast to all the known
individual listeners. Upon a time out of the Query Interval, the 6LR individual listeners. Upon a time out of the Query Interval, the 6LR
sends a Query to each of its listeners, and gets a Report back that sends a Query to each of its listeners, and gets a Report back that
is mapped into a DAO, as illustrated in Figure 11: is mapped into a DAO, as illustrated in Figure 13:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
| Report | | | | Report | | |
|------------------->| | | |------------------->| | |
| | DAO | | | | DAO | |
| |-------------->| | | |-------------->| |
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | | | | | |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
| | | | | | | |
Figure 11: Next Registration Flow Figure 13: 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.
11. Security Considerations 11. Security Considerations
First of all, it is worth noting that with [RFC6550], every node in
the LLN is RPL-aware and can inject any RPL-based attack in the
network. This specification isolates edge nodes that can only
interact with the RPL routers using 6LoWPAN ND, meaning that they
cannot perform RPL insider attacks. 6LoWPAN ND can optionally provide
SAVI features, which reduces even more the attack perimeter that is
available to the edge nodes.
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, (see [RFC7416] section 7) or bombing attack whereby as black-holing, (see [RFC7416] section 7) or bombing attack whereby
an impersonated 6LBR would destroy state in the network by using the an impersonated 6LBR would destroy state in the network by using the
"Removed" Status code. "Removed" Status code.
This trust model could be at a minimum based on a Layer-2 Secure This trust model could be at a minimum based on a Layer-2 Secure
joining and the Link-Layer security. This is a generic 6LoWPAN joining and the Link-Layer security. This is a generic 6LoWPAN
requirement, see Req5.1 in Appendix of [RFC8505]. requirement, see Req5.1 in Appendix of [RFC8505].
skipping to change at page 26, line 38 skipping to change at page 28, line 31
create a binding state in the 6LBR but it can be used to maintain one create a binding state in the 6LBR but it can be used to maintain one
active longer than expected. active longer than expected.
Note that a full EDAR message with a lifetime of 0 will destroy that Note that a full EDAR message with a lifetime of 0 will destroy that
state and the anonymous message will not recreate it. Note also that state and the anonymous message will not recreate it. Note also that
a rogue that has access to the network can attack the 6LBR with other a rogue that has access to the network can attack the 6LBR with other
(forged) addresses and ROVR, and that this is a much easier DoS (forged) addresses and ROVR, and that this is a much easier DoS
attack than trying to keep existing state alive longer. attack than trying to keep existing state alive longer.
At the time of this writing RPL does not have a zerotrust model 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 whereby it is possible to validate the origin of an address that is
is injected in a DAO. This specification makes a first step in that 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 direction by allowing the Root to challenge the RUL by the 6LR that
serves it. serves it.
12. IANA Considerations 12. IANA Considerations
12.1. Resizing the ARO Status values 12.1. Resizing the ARO Status values
IANA is requested to modify the Address Registration Option Status IANA is requested to modify the Address Registration Option Status
Values Registry as follows: The unassigned values range is reduced Values Registry as follows: The unassigned values range is reduced
from 11-255 to 11-63. from 11-255 to 11-63.
skipping to change at page 27, line 28 skipping to change at page 29, line 23
12.3. RPL Target Option Flags 12.3. RPL Target Option Flags
Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL
Target Option Flags field. This specification reduces the field to 4 Target Option Flags field. This specification reduces the field to 4
bits. The IANA is requested to reduce the size of the registry bits. The IANA is requested to reduce the size of the registry
accordingly. accordingly.
12.4. New Subregistry for the RPL Non-Rejection Status values 12.4. New Subregistry for the RPL Non-Rejection Status values
This specification creates a new Subregistry for the RPL Non- This specification creates a new Subregistry for the RPL Non-
Rejection Status values for use in RPL DAO-ACK and RCO messages, Rejection Status values for use in RPL DAO-ACK and DCO messages,
under the ICMPv6 parameters registry. under the ICMPv6 parameters registry.
* Possible values are 6-bit unsigned integers (0..63). * Possible values are 6-bit unsigned integers (0..63).
* Registration procedure is "Standards Action" [RFC8126]. * Registration procedure is "Standards Action" [RFC8126].
* Initial allocation is as indicated in Table 3: * Initial allocation is as indicated in Table 3:
+-------+------------------------+-----------+ +-------+------------------------+-----------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
skipping to change at page 28, line 17 skipping to change at page 30, line 13
* Initial allocation is as indicated in Table 4: * Initial allocation is as indicated in Table 4:
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+=======+=======================+===============+ +=======+=======================+===============+
| 0 | Unqualified rejection | This document | | 0 | Unqualified rejection | This document |
+-------+-----------------------+---------------+ +-------+-----------------------+---------------+
Table 4: Rejection values of the RPL Status Table 4: Rejection values of the RPL Status
13. Acknowledgments 13. acknowledgments
The authors wish to thank Georgios Papadopoulos for their early The authors wish to thank Georgios Papadopoulos and Rahul Jadhav for
reviews of and contributions to this document their early reviews of and contributions to this document
14. Normative References 14. 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>.
[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,
skipping to change at page 30, line 33 skipping to change at page 32, line 28
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, [AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
"Address Protected Neighbor Discovery for Low-power and "Address Protected Neighbor Discovery for Low-power and
Lossy Networks", Work in Progress, Internet-Draft, draft- Lossy Networks", Work in Progress, Internet-Draft, draft-
ietf-6lo-ap-nd-20, 9 March 2020, ietf-6lo-ap-nd-20, 9 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-20>. <https://tools.ietf.org/html/draft-ietf-6lo-ap-nd-20>.
[USEofRPLinfo] [USEofRPLinfo]
Robles, I., Richardson, M., and P. Thubert, "Using RPI Robles, I., Richardson, M., and P. Thubert, "Using RPI
option Type, Routing Header for Source Routes and IPv6-in- Option Type, Routing Header for Source Routes and IPv6-in-
IPv6 encapsulation in the RPL Data Plane", Work in IPv6 encapsulation in the RPL Data Plane", Work in
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-36, Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-38,
26 February 2020, <https://tools.ietf.org/html/draft-ietf- 23 March 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-36>. roll-useofrplinfo-38>.
[EFFICIENT-NPDAO] [EFFICIENT-NPDAO]
Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient
Route Invalidation", Work in Progress, Internet-Draft, Route Invalidation", Work in Progress, Internet-Draft,
draft-ietf-roll-efficient-npdao-17, 30 October 2019, draft-ietf-roll-efficient-npdao-17, 30 October 2019,
<https://tools.ietf.org/html/draft-ietf-roll-efficient- <https://tools.ietf.org/html/draft-ietf-roll-efficient-
npdao-17>. npdao-17>.
15. Informative References 15. Informative References
skipping to change at page 31, line 38 skipping to change at page 33, line 33
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 [RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504, Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
January 2019, <https://www.rfc-editor.org/info/rfc8504>. January 2019, <https://www.rfc-editor.org/info/rfc8504>.
[6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 [6BBR] Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", Work in Progress, Internet-Draft, draft- Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-19, 3 March 2020, ietf-6lo-backbone-router-20, 23 March 2020,
<https://tools.ietf.org/html/draft-ietf-6lo-backbone- <https://tools.ietf.org/html/draft-ietf-6lo-backbone-
router-19>. router-20>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 12 illustrates the case in Storing Mode where the packet is Figure 14 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].
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|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
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4 bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
<- No RPL artifact ... <- No RPL artifact ...
Figure 12: Encapsulation to Parent 6LR in Storing Mode Figure 14: Encapsulation to Parent 6LR in Storing Mode
The difference with the example format presented in Figure 19 of The difference with the example presented in Figure 19 of [RFC8138]
[RFC8138] is the addition of a SRH-6LoRH before the RPI-6LoRH to is the addition of a SRH-6LoRH before the RPI-6LoRH to transport the
transport the compressed address of the 6LR as the destination compressed address of the 6LR as the destination address of the outer
address of the outer IPv6 header. In the original example the IPv6 header. In the original example the destination IP of the outer
destination IP of the outer header was elided and was implicitly the header was elided and was implicitly the same address as the
same address as the destination of the inner header. Type 1 was destination of the inner header. Type 1 was arbitrarily chosen, and
arbitrarily chosen for this example, and the size of 0 denotes a the size of 0 denotes a single address in the SRH.
single address in the SRH.
In Figure 12, the source of the IP-in-IP encapsulation is the Root, In Figure 14, 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 so 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 12 with possibly more hops in the SRH- to that represented in Figure 14 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 The SRH-6LoRHs are followed by RPI-6LoRH and then the IP-in-IP 6LoRH.
6LoRH is removed, all the Router headers that precede it are also When the IP-in-IP 6LoRH is removed, all the 6LoRH Headers that
removed. precede it are also removed. The Paging Dispatch [RFC8025] may also
be removed if there was no previous Page change to a Page other than
The Paging Dispatch [RFC8025] may also be removed if there was no 0 or 1, since the LOWPAN_IPHC is encoded in the same fashion in the
previous Page change to a Page other than 0 or 1, since the default Page 0 and in Page 1. The resulting packet to the
LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and destination is the inner packet compressed with [RFC6282].
in Page 1. The resulting packet to the destination is the inner
packet compressed with [RFC6282].
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
06254 Mougins - Sophia Antipolis 06254 Mougins - Sophia Antipolis
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
 End of changes. 82 change blocks. 
206 lines changed or deleted 285 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/