draft-ietf-roll-useofrplinfo-32.txt   draft-ietf-roll-useofrplinfo-33.txt 
ROLL Working Group M. Robles ROLL Working Group M. Robles
Internet-Draft Aalto/UTN-FRM Internet-Draft Aalto
Updates: 6553, 6550, 8138 (if approved) M. Richardson Updates: 6553, 6550, 8138 (if approved) M. Richardson
Intended status: Standards Track SSW Intended status: Standards Track SSW
Expires: May 7, 2020 P. Thubert Expires: June 15, 2020 P. Thubert
Cisco Cisco
November 4, 2019 December 13, 2019
Using RPL Option Type, Routing Header for Source Routes and IPv6-in-IPv6 Using RPI Option Type, Routing Header for Source Routes and IPv6-in-IPv6
encapsulation in the RPL Data Plane encapsulation in the RPL Data Plane
draft-ietf-roll-useofrplinfo-32 draft-ietf-roll-useofrplinfo-33
Abstract Abstract
This document looks at different data flows through LLN (Low-Power This document looks at different data flows through LLN (Low-Power
and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power
and Lossy Networks) is used to establish routing. The document and Lossy Networks) is used to establish routing. The document
enumerates the cases where RFC6553 (RPL Option Type), RFC6554 enumerates the cases where RFC6553 (RPI Option Type), RFC6554
(Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is (Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is
required in data plane. This analysis provides the basis on which to required in data plane. This analysis provides the basis on which to
design efficient compression of these headers. This document updates design efficient compression of these headers. This document updates
RFC6553 adding a change to the RPL Option Type. Additionally, this RFC6553 adding a change to the RPI Option Type. Additionally, this
document updates RFC6550 defining a flag in the DIO Configuration document updates RFC6550 defining a flag in the DIO Configuration
Option to indicate about this change and updates RFC8138 as well to Option to indicate about this change and updates RFC8138 as well to
consider the new Option Type when the RPL Option is decompressed. consider the new Option Type when the RPL Option is decompressed.
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 May 7, 2020. This Internet-Draft will expire on June 15, 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology and Requirements Language . . . . . . . . . . . . 4 2. Terminology and Requirements Language . . . . . . . . . . . . 5
3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6 3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 7 4. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 7
4.1. Updates to RFC6550: Advertise External Routes with Non- 4.1. Updates to RFC6550: Advertising External Routes with Non-
Storing Mode Signaling. . . . . . . . . . . . . . . . . . 7 Storing Mode Signaling. . . . . . . . . . . . . . . . . . 7
4.2. Updates to RFC6553: Indicating the new RPI value. . . . . 8 4.2. Updates to RFC6553: Indicating the new RPI Option Type. . 8
4.3. Updates to RFC6550: Indicating the new RPI in the 4.3. Updates to RFC6550: Indicating the new RPI in the
DODAG Configuration Option Flag. . . . . . . . . . . . . 11 DODAG Configuration Option Flag. . . . . . . . . . . . . 11
4.4. Updates to RFC8138: Indicating the way to decompress with 4.4. Updates to RFC8138: Indicating the way to decompress with
the new RPI value. . . . . . . . . . . . . . . . . . . . 12 the new RPI Option Type. . . . . . . . . . . . . . . . . 12
5. Sample/reference topology . . . . . . . . . . . . . . . . . . 14 5. Sample/reference topology . . . . . . . . . . . . . . . . . . 14
6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 19 7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Storing Mode: Interaction between Leaf and Root . . . . . 20 7.1. Storing Mode: Interaction between Leaf and Root . . . . . 20
7.1.1. SM: Example of Flow from RAL to root . . . . . . . . 21 7.1.1. SM: Example of Flow from RAL to root . . . . . . . . 21
7.1.2. SM: Example of Flow from root to RAL . . . . . . . . 21 7.1.2. SM: Example of Flow from root to RAL . . . . . . . . 21
7.1.3. SM: Example of Flow from root to RUL . . . . . . . . 22 7.1.3. SM: Example of Flow from root to RUL . . . . . . . . 22
7.1.4. SM: Example of Flow from RUL to root . . . . . . . . 23 7.1.4. SM: Example of Flow from RUL to root . . . . . . . . 23
7.2. SM: Interaction between Leaf and Internet. . . . . . . . 23 7.2. SM: Interaction between Leaf and Internet. . . . . . . . 23
7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 24 7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 24
skipping to change at page 3, line 33 skipping to change at page 3, line 33
12. Security Considerations . . . . . . . . . . . . . . . . . . . 49 12. Security Considerations . . . . . . . . . . . . . . . . . . . 49
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 52 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 52
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 52 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
14.1. Normative References . . . . . . . . . . . . . . . . . . 52 14.1. Normative References . . . . . . . . . . . . . . . . . . 52
14.2. Informative References . . . . . . . . . . . . . . . . . 54 14.2. Informative References . . . . . . . . . . . . . . . . . 54
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 56 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 56
1. Introduction 1. Introduction
RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)
[RFC6550] is a routing protocol for constrained networks. RFC6553 [RFC6550] is a routing protocol for constrained networks. [RFC6553]
[RFC6553] defines the "RPL option" (RPL Packet Information or RPI), defines the RPL Option carried within the IPv6 Hop-by-Hop Header to
carried within the IPv6 Hop-by-Hop header to quickly identify carry the RPLInstanceID and quickly identify inconsistencies (loops)
inconsistencies (loops) in the routing topology. RFC6554 [RFC6554] in the routing topology. The RPL Option is commonly referred to as
defines the "RPL Source Route Header" (RH3), an IPv6 Extension Header the RPL Packet Information (RPI) though the RPI is really the
to deliver datagrams within a RPL routing domain, particularly in abstract information that is defined in [RFC6550] and transported in
non-storing mode. the RPL Option. RFC6554 [RFC6554] defines the "RPL Source Route
Header" (RH3), an IPv6 Extension Header to deliver datagrams within a
RPL routing domain, particularly in non-storing mode.
These various items are referred to as RPL artifacts, and they are These various items are referred to as RPL artifacts, and they are
seen on all of the data-plane traffic that occurs in RPL routed seen on all of the data-plane traffic that occurs in RPL routed
networks; they do not in general appear on the RPL control plane networks; they do not in general appear on the RPL control plane
traffic at all which is mostly hop-by-hop traffic (one exception traffic at all which is mostly hop-by-hop traffic (one exception
being DAO messages in non-storing mode). being DAO messages in non-storing mode).
It has become clear from attempts to do multi-vendor It has become clear from attempts to do multi-vendor
interoperability, and from a desire to compress as many of the above interoperability, and from a desire to compress as many of the above
artifacts as possible that not all implementers agree when artifacts artifacts as possible that not all implementers agree when artifacts
are necessary, or when they can be safely omitted, or removed. are necessary, or when they can be safely omitted, or removed.
The ROLL WG analysized how [RFC2460] rules apply to storing and non- The ROLL WG analysized how [RFC2460] rules apply to storing and non-
storing use of RPL. The result was 24 data plane use cases. They storing use of RPL. The result was 24 data plane use cases. They
are exhaustively outlined here in order to be completely unambiguous. are exhaustively outlined here in order to be completely unambiguous.
During the processing of this document, new rules were published as During the processing of this document, new rules were published as
[RFC8200], and this document was updated to reflect the normative [RFC8200], and this document was updated to reflect the normative
changes in that document. changes in that document.
This document updates RFC6553, changing the RPI option value to make This document updates RFC6553, changing the value of the Option Type
RFC8200 routers ignore this option by default. of the RPL Option to make RFC8200 routers ignore this option when not
recognized.
A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a
mechanism for compressing RPL Option information and Routing Header mechanism for compressing RPL Option information and Routing Header
type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6 type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6
technique. technique.
Since some of the uses cases here described, use IPv6-in-IPv6 Since some of the uses cases here described, use IPv6-in-IPv6
encapsulation. It MUST take in consideration, when encapsulation is encapsulation. It MUST take in consideration, when encapsulation is
applied, the RFC6040 [RFC6040], which defines how the explicit applied, the RFC6040 [RFC6040], which defines how the explicit
congestion notification (ECN) field of the IP header should be congestion notification (ECN) field of the IP header should be
skipping to change at page 4, line 44 skipping to change at page 4, line 47
1.1. Overview 1.1. Overview
The rest of the document is organized as follows: Section 2 describes The rest of the document is organized as follows: Section 2 describes
the used terminology. Section 3 provides a RPL Overview. Section 4 the used terminology. Section 3 provides a RPL Overview. Section 4
describes the updates to RFC6553, RFC6550 and RFC 8138. Section 5 describes the updates to RFC6553, RFC6550 and RFC 8138. Section 5
provides the reference topology used for the uses cases. Section 6 provides the reference topology used for the uses cases. Section 6
describes the uses cases included. Section 7 describes the storing describes the uses cases included. Section 7 describes the storing
mode cases and section 8 the non-storing mode cases. Section 9 mode cases and section 8 the non-storing mode cases. Section 9
describes the operational considerations of supporting RPL-unaware- describes the operational considerations of supporting RPL-unaware-
leaves. Section 10 depicts operational considerations for the leaves. Section 10 depicts operational considerations for the
proposed change on RPL Option type, section 11 the IANA proposed change on RPI Option Type, section 11 the IANA
considerations and then section 12 describes the security aspects. considerations and then section 12 describes the security aspects.
2. Terminology and Requirements Language 2. Terminology and Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
skipping to change at page 5, line 20 skipping to change at page 5, line 26
RPL Leaf: An IPv6 host that is attached to a RPL router and obtains RPL Leaf: An IPv6 host that is attached to a RPL router and obtains
connectivity through a RPL Destination Oriented Directed Acyclic connectivity through a RPL Destination Oriented Directed Acyclic
Graph (DODAG). As an IPv6 node, a RPL Leaf is expected to ignore a Graph (DODAG). As an IPv6 node, a RPL Leaf is expected to ignore a
consumed Routing Header and as an IPv6 host, it is expected to ignore consumed Routing Header and as an IPv6 host, it is expected to ignore
a Hop-by-Hop header. It results that a RPL Leaf can correctly a Hop-by-Hop header. It results that a RPL Leaf can correctly
receive a packet with RPL artifacts. On the other hand, a RPL Leaf receive a packet with RPL artifacts. On the other hand, a RPL Leaf
is not expected to generate RPL artifacts or to support IP-in-IP is not expected to generate RPL artifacts or to support IP-in-IP
encapsulation. For simplification, this document uses the standalone encapsulation. For simplification, this document uses the standalone
term leaf to mean a RPL leaf. term leaf to mean a RPL leaf.
RPL Packet Information (RPI): The abstract information that [RFC6550]
places in IP packets. The term is commonly used, including in this
document, to refer to the RPL Option [RFC6553] that transports that
abstract information in an IPv6 Hob-by-Hop Header.
RPL-aware-node (RAN): A device which implements RPL. Please note RPL-aware-node (RAN): A device which implements RPL. Please note
that the device can be found inside the LLN or outside LLN. that the device can be found inside the LLN or outside LLN.
RPL-Aware-Leaf(RAL): A RPL-aware-node that is also a RPL Leaf. RPL-Aware-Leaf(RAL): A RPL-aware-node that is also a RPL Leaf.
RPL-unaware-node: A device which does not implement RPL, thus the RPL-unaware-node: A device which does not implement RPL, thus the
device is not-RPL-aware. Please note that the device can be found device is not-RPL-aware. Please note that the device can be found
inside the LLN. inside the LLN.
RPL-Unaware-Leaf(RUL): A RPL-unaware-node that is also a RPL Leaf. RPL-Unaware-Leaf(RUL): A RPL-unaware-node that is also a RPL Leaf.
skipping to change at page 5, line 41 skipping to change at page 6, line 4
6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any 6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any
host or router participating in a LoWPAN. This term is used when host or router participating in a LoWPAN. This term is used when
referring to situations in which either a host or router can play the referring to situations in which either a host or router can play the
role described.". In this document, a 6LN acts as a leaf. role described.". In this document, a 6LN acts as a leaf.
6LoWPAN Router (6LR): [RFC6775] defines it as:" An intermediate 6LoWPAN Router (6LR): [RFC6775] defines it as:" An intermediate
router in the LoWPAN that is able to send and receive Router router in the LoWPAN that is able to send and receive Router
Advertisements (RAs) and Router Solicitations (RSs) as well as Advertisements (RAs) and Router Solicitations (RSs) as well as
forward and route IPv6 packets. 6LoWPAN routers are present only in forward and route IPv6 packets. 6LoWPAN routers are present only in
route-over topologies." route-over topologies."
6LoWPAN Border Router (6LBR): [RFC6775] defines it as:"A border 6LoWPAN Border Router (6LBR): [RFC6775] defines it as:"A border
router located at the junction of separate 6LoWPAN networks or router located at the junction of separate 6LoWPAN networks or
between a 6LoWPAN network and another IP network. There may be one between a 6LoWPAN network and another IP network. There may be one
or more 6LBRs at the 6LoWPAN network boundary. A 6LBR is the or more 6LBRs at the 6LoWPAN network boundary. A 6LBR is the
responsible authority for IPv6 prefix propagation for the 6LoWPAN responsible authority for IPv6 prefix propagation for the 6LoWPAN
network it is serving. An isolated LoWPAN also contains a 6LBR in network it is serving. An isolated LoWPAN also contains a 6LBR in
the network, which provides the prefix(es) for the isolated network." the network, which provides the prefix(es) for the isolated network."
Flag Day: A transition that involves having a network with different Flag Day: A transition that involves having a network with different
values of RPL Option Type. Thus the network does not work correctly values of RPI Option Type. Thus the network does not work correctly
(Lack of interoperation). (Lack of interoperation).
Hop-by-hop re-encapsulation: The term "hop-by-hop re-encapsulation" Hop-by-hop re-encapsulation: The term "hop-by-hop re-encapsulation"
header refers to adding a header that originates from a node to an header refers to adding a header that originates from a node to an
adjacent node, using the addresses (usually the GUA or ULA, but could adjacent node, using the addresses (usually the GUA or ULA, but could
use the link-local addresses) of each node. If the packet must use the link-local addresses) of each node. If the packet must
traverse multiple hops, then it must be decapsulated at each hop, and traverse multiple hops, then it must be decapsulated at each hop, and
then re-encapsulated again in a similar fashion. then re-encapsulated again in a similar fashion.
Non-Storing Mode (Non-SM): RPL mode of operation in which the RPL- Non-Storing Mode (Non-SM): RPL mode of operation in which the RPL-
skipping to change at page 7, line 36 skipping to change at page 7, line 36
RPL supports two modes of Downward traffic: in storing mode (SM), it RPL supports two modes of Downward traffic: in storing mode (SM), it
is fully stateful; in non-storing mode (Non-SM), it is fully source is fully stateful; in non-storing mode (Non-SM), it is fully source
routed. A RPL Instance is either fully storing or fully non-storing, routed. A RPL Instance is either fully storing or fully non-storing,
i.e. a RPL Instance with a combination of storing and non-storing i.e. a RPL Instance with a combination of storing and non-storing
nodes is not supported with the current specifications at the time of nodes is not supported with the current specifications at the time of
writing this document. writing this document.
4. Updates to RFC6553, RFC6550 and RFC8138 4. Updates to RFC6553, RFC6550 and RFC8138
4.1. Updates to RFC6550: Advertise External Routes with Non-Storing 4.1. Updates to RFC6550: Advertising External Routes with Non-Storing
Mode Signaling. Mode Signaling.
Section 6.7.8. of [RFC6550] introduces the 'E' flag that is set to Section 6.7.8. of [RFC6550] introduces the 'E' flag that is set to
indicate that the 6LR that generates the DAO redistributes external indicate that the 6LR that generates the DAO redistributes external
targets into the RPL network. An external Target is a Target that targets into the RPL network. An external Target is a Target that
has been learned through an alternate protocol, for instance a route has been learned through an alternate protocol, for instance a route
to a prefix that is outside the RPL domain but reachable via a 6LR. to a prefix that is outside the RPL domain but reachable via a 6LR.
Being outside of the RPL domain, a node that is reached via an Being outside of the RPL domain, a node that is reached via an
external target cannot be guaranteed to ignore the RPL artifacts and external target cannot be guaranteed to ignore the RPL artifacts and
cannot be expected to process the [RFC8138] compression correctly. cannot be expected to process the [RFC8138] compression correctly.
skipping to change at page 8, line 39 skipping to change at page 8, line 39
by [RFC8504]. If the 6LN is a RUL, the Root that encapsulates a by [RFC8504]. If the 6LN is a RUL, the Root that encapsulates a
packet SHOULD terminate the tunnel at a parent 6LR unless it is aware packet SHOULD terminate the tunnel at a parent 6LR unless it is aware
that the RUL supports IP-in-IP decapsulation. that the RUL supports IP-in-IP decapsulation.
A node that is reachable over an external route is not expected to A node that is reachable over an external route is not expected to
support [RFC8138]. Whether a decapsulation took place or not and support [RFC8138]. Whether a decapsulation took place or not and
even when the 6LR is delivering the packet to a RUL, the 6LR that even when the 6LR is delivering the packet to a RUL, the 6LR that
injected an external route MUST uncompress the packet before injected an external route MUST uncompress the packet before
forwarding over that external route. forwarding over that external route.
4.2. Updates to RFC6553: Indicating the new RPI value. 4.2. Updates to RFC6553: Indicating the new RPI Option Type.
This modification is required to be able to send, for example, IPv6 This modification is required to be able to send, for example, IPv6
packets from a RPL-Aware-Leaf to a RPL-unaware node through Internet packets from a RPL-Aware-Leaf to a RPL-unaware node through Internet
(see Section 7.2.1), without requiring IPv6-in-IPv6 encapsulation. (see Section 7.2.1), without requiring IPv6-in-IPv6 encapsulation.
[RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in [RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in
the Option Type field of the RPL Option header, the two high order the Option Type field of the RPL Option, the two high order bits must
bits must be set to '01' and the third bit is equal to '1'. The be set to '01' and the third bit is equal to '1'. The first two bits
first two bits indicate that the IPv6 node must discard the packet if indicate that the IPv6 node must discard the packet if it doesn't
it doesn't recognize the option type, and the third bit indicates recognize the Option Type, and the third bit indicates that the
that the Option Data may change in route. The remaining bits serve Option Data may change in route. The remaining bits serve as the
as the option type. Option Type.
+-------+-------------------+----------------+-----------+ +-------+-------------------+----------------+-----------+
| Hex | Binary Value | Description | Reference | | Hex | Binary Value | Description | Reference |
+ Value +-------------------+ + + + Value +-------------------+ + +
| | act | chg | rest | | | | | act | chg | rest | | |
+-------+-----+-----+-------+----------------+-----------+ +-------+-----+-----+-------+----------------+-----------+
| 0x63 | 01 | 1 | 00011 | RPL Option | [RFC6553] | | 0x63 | 01 | 1 | 00011 | RPL Option | [RFC6553] |
+-------+-----+-----+-------+----------------+-----------+ +-------+-----+-----+-------+----------------+-----------+
Figure 2: Option Type in RPL Option. Figure 2: Option Type in RPL Option.
This document illustrates that is is not always possible to know for This document illustrates that is is not always possible to know for
sure at the source that a packet will only travel within the RPL sure at the source that a packet will only travel within the RPL
domain or may leave it. domain or may leave it.
At the time [RFC6553] was published, leaking a Hop-by-Hop header in At the time [RFC6553] was published, leaking a Hop-by-Hop header in
the outer IPv6 header chain could potentially impact core routers in the outer IPv6 header chain could potentially impact core routers in
the internet. So at that time, it was decided to encapsulate any the internet. So at that time, it was decided to encapsulate any
packet with a RPL option using IPv6-in-IPv6 in all cases where it was packet with a RPL Option using IPv6-in-IPv6 in all cases where it was
unclear whether the packet would remain within the RPL domain. In unclear whether the packet would remain within the RPL domain. In
the exception case where a packet would still leak, the Option Type the exception case where a packet would still leak, the Option Type
would ensure that the first router in the Internet that does not would ensure that the first router in the Internet that does not
recognize the option would drop the packet and protect the rest of recognize the option would drop the packet and protect the rest of
the network. the network.
Even with [RFC8138] that compresses the IPv6-in-IPv6 header, this Even with [RFC8138] that compresses the IPv6-in-IPv6 header, this
approach yields extra bytes in a packet which means consuming more approach yields extra bytes in a packet which means consuming more
energy, more bandwidth, incurring higher chances of loss and possibly energy, more bandwidth, incurring higher chances of loss and possibly
causing a fragmentation at the 6LoWPAN level. This impacts the daily causing a fragmentation at the 6LoWPAN level. This impacts the daily
operation of constrained devices for a case that generally does not operation of constrained devices for a case that generally does not
happen and would not heavily impact the core anyway. happen and would not heavily impact the core anyway.
While intention was and remains that the Hop-by-Hop header with a RPL While intention was and remains that the Hop-by-Hop header with a RPL
option should be confined within the RPL domain, this specification Option should be confined within the RPL domain, this specification
modifies this behavior in order to reduce the dependency on IPv6-in- modifies this behavior in order to reduce the dependency on IPv6-in-
IPv6 and protect the constrained devices. Section 4 of [RFC8200] IPv6 and protect the constrained devices. Section 4 of [RFC8200]
clarifies the behaviour of routers in the Internet as follows: "it is clarifies the behaviour of routers in the Internet as follows: "it is
now expected that nodes along a packet's delivery path only examine now expected that nodes along a packet's delivery path only examine
and process the Hop-by-Hop Options header if explicitly configured to and process the Hop-by-Hop Options header if explicitly configured to
do so". do so".
When unclear about the travel of a packet, it becomes preferable for When unclear about the travel of a packet, it becomes preferable for
a source not to encapsulate, accepting the fact that the packet may a source not to encapsulate, accepting the fact that the packet may
leave the RPL domain on its way to its destination. In that event, leave the RPL domain on its way to its destination. In that event,
the packet should reach its destination and should not be discarded the packet should reach its destination and should not be discarded
by the first node that does not recognize the RPL option. But with by the first node that does not recognize the RPL Option. But with
the current value of the Option Type, if a node in the Internet is the current value of the Option Type, if a node in the Internet is
configured to process the Hop-by-Hop header, and if such node configured to process the Hop-by-Hop header, and if such node
encounters an option with the first two bits set to 01 and conforms encounters an option with the first two bits set to 01 and conforms
to [RFC8200], it will drop the packet. Host systems should do the to [RFC8200], it will drop the packet. Host systems should do the
same, irrespective of the configuration. same, irrespective of the configuration.
Thus, this document updates the Option Type field to (Figure 3): the Thus, this document updates the Option Type of the RPL Option
two high order bits MUST be set to '00' and the third bit is equal to [RFC6553], abusively naming it RPI Option Type for simplicity, to
'1'. The first two bits indicate that the IPv6 node MUST skip over (Figure 3): the two high order bits MUST be set to '00' and the third
this option and continue processing the header ([RFC8200] bit is equal to '1'. The first two bits indicate that the IPv6 node
Section 4.2) if it doesn't recognize the option type, and the third MUST skip over this option and continue processing the header
bit continues to be set to indicate that the Option Data may change ([RFC8200] Section 4.2) if it doesn't recognize the Option Type, and
en route. The remaining bits serve as the option type and remain as the third bit continues to be set to indicate that the Option Data
0x3. This ensures that a packet that leaves the RPL domain of an LLN may change en route. The five rightmost bits remain at 0x3. This
(or that leaves the LLN entirely) will not be discarded when it ensures that a packet that leaves the RPL domain of an LLN (or that
contains the [RFC6553] RPL Hop-by-Hop option known as RPI. leaves the LLN entirely) will not be discarded when it contains the
RPL Option.
With the new Option Type, if an IPv6 (intermediate) node (RPL-not- With the new Option Type, if an IPv6 (intermediate) node (RPL-not-
capable) receives a packet with an RPL Option, it should ignore the capable) receives a packet with an RPL Option, it should ignore the
Hop-by-Hop RPL option (skip over this option and continue processing Hop-by-Hop RPL Option (skip over this option and continue processing
the header). This is relevant, as it was mentioned previously, in the header). This is relevant, as it was mentioned previously, in
the case that there is a flow from RAL to Internet (see the case that there is a flow from RAL to Internet (see
Section 7.2.1). Section 7.2.1).
This is a significant update to [RFC6553]. This is a significant update to [RFC6553].
+-------+-------------------+-------------+------------+ +-------+-------------------+-------------+------------+
| Hex | Binary Value | Description | Reference | | Hex | Binary Value | Description | Reference |
+ Value +-------------------+ + + + Value +-------------------+ + +
| | act | chg | rest | | | | | act | chg | rest | | |
+-------+-----+-----+-------+-------------+------------+ +-------+-----+-----+-------+-------------+------------+
| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)| | 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|
+-------+-----+-----+-------+-------------+------------+ +-------+-----+-----+-------+-------------+------------+
Figure 3: Revised Option Type in RPL Option. (*)represents this Figure 3: Revised Option Type in RPL Option. (*)represents this
document document
Without the signaling described below, this change would otherwise Without the signaling described below, this change would otherwise
create a lack of interoperation (flag day) for existing networks create a lack of interoperation (flag day) for existing networks
which are currently using 0x63 as the RPI value. A move to 0x23 will which are currently using 0x63 as the RPI Option Type value. A move
not be understood by those networks. It is suggested that RPL to 0x23 will not be understood by those networks. It is suggested
implementations accept both 0x63 and 0x23 when processing the header. that RPL implementations accept both 0x63 and 0x23 when processing
the header.
When forwarding packets, implementations SHOULD use the same value as When forwarding packets, implementations SHOULD use the same value as
it was received (This is required because, RPI type code can not be it was received. This is required because, RPI Option Type can not
changed by [RFC8200] - Section 4.2). It allows to the network to be be changed by [RFC8200] - Section 4.2. It allows to the network to
incrementally upgraded, and for the DODAG root to know which parts of be incrementally upgraded, and for the DODAG root to know which parts
the network are upgraded. of the network are upgraded.
When originating new packets, implementations SHOULD have an option When originating new packets, implementations SHOULD have an option
to determine which value to originate with, this option is controlled to determine which value to originate with, this option is controlled
by the DIO option described below. by the DIO option described below.
A network which is switching from straight 6LoWPAN compression The change of RPI Option Type from 0x63 to 0x23, makes all [RFC8200]
mechanism to those described in [RFC8138] will experience a flag day
in the data compression anyway, and if possible this change can be
deployed at the same time.
The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]
Section 4.2 compliant nodes tolerant of the RPL artifacts. There is Section 4.2 compliant nodes tolerant of the RPL artifacts. There is
therefore no longer a necessity to remove the artifacts when sending therefore no longer a necessity to remove the artifacts when sending
traffic to the Internet. This change clarifies when to use an IPv6- traffic to the Internet. This change clarifies when to use an IPv6-
in-IPv6 header, and how to address them: The Hop-by-Hop Options in-IPv6 header, and how to address them: The Hop-by-Hop Options
Header containing the RPI option MUST always be added when 6LRs Header containing the RPI MUST always be added when 6LRs originate
originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6 packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6 headers MUST
headers MUST always be added when a 6LR find that it needs to insert always be added when a 6LR find that it needs to insert a Hop-by-Hop
a Hop-by-Hop Options Header containing the RPI option. The IPv6-in- Options Header containing the RPL Option. The IPv6-in-IPv6 header is
IPv6 header is to be addressed to the RPL root when on the way up, to be addressed to the RPL root when on the way up, and to the end-
and to the end-host when on the way down. host when on the way down.
In the non-storing case, dealing with not-RPL aware leaf nodes is In the non-storing case, dealing with not-RPL aware leaf nodes is
much easier as the 6LBR (DODAG root) has complete knowledge about the much easier as the 6LBR (DODAG root) has complete knowledge about the
connectivity of all DODAG nodes, and all traffic flows through the connectivity of all DODAG nodes, and all traffic flows through the
root node. root node.
The 6LBR can recognize not-RPL aware leaf nodes because it will The 6LBR can recognize not-RPL aware leaf nodes because it will
receive a DAO about that node from the 6LR immediately above that receive a DAO about that node from the 6LR immediately above that
not-RPL aware node. This means that the non-storing mode case can not-RPL aware node. This means that the non-storing mode case can
avoid ever using hop-by-hop re-encapsulation headers for traffic avoid ever using hop-by-hop re-encapsulation headers for traffic
originating from the root to the leafs. originating from the root to the leafs.
The non-storing mode case does not require the type change from 0x63 The non-storing mode case does not require the type change from 0x63
to 0x23, as the root can always create the right packet. The type to 0x23, as the root can always create the right packet. The type
change does not adversely affect the non-storing case. change does not adversely affect the non-storing case.
4.3. Updates to RFC6550: Indicating the new RPI in the DODAG 4.3. Updates to RFC6550: Indicating the new RPI in the DODAG
Configuration Option Flag. Configuration Option Flag.
In order to avoid a Flag Day caused by lack of interoperation between In order to avoid a Flag Day caused by lack of interoperation between
new RPI (0x23) and old RPI (0x63) nodes, this section defines a flag new RPI Option Type (0x23) and old RPI Option Type (0x63) nodes, this
in the DIO Configuration Option, to indicate when then new RPI value section defines a flag in the DIO Configuration Option, to indicate
can be safely used. This means, the flag is going to indicate the when then new RPI Option Type can be safely used. This means, the
type of RPI that the network is using. Thus, when a node join to a flag is going to indicate the value of Option Type that the network
network will know which value to use. With this, RPL-capable nodes is using for the RPL Option. Thus, when a node join to a network
know if it is safe to use 0x23 when creating a new RPI. A node that will know which value to use. With this, RPL-capable nodes know if
forwards a packet with an RPI MUST NOT modify the option type of the it is safe to use 0x23 when creating a new RPL Option. A node that
RPI. forwards a packet with an RPI MUST NOT modify the Option Type of the
RPL Option.
This is done via a DODAG Configuration Option flag which will This is done using a DODAG Configuration Option flag which will
propagate through the network. If the flag is received with a value signal "RPI 0x23 enable" and propagate through the network.
zero (which is the default), then new nodes will remain in RFC6553 Section 6.3.1. of [RFC6550] defines a 3-bit Mode of Operation (MOP)
Compatible Mode; originating traffic with the old-RPI (0x63) value. in the DIO Base Object. The flag is defined only for MOP value
between 0 to 6. For a MOP value of 7 or above, the flag MAY indicate
something different and MUST NOT be interpreted as "RPI 0x23 enable"
unless the specification of the MOP indicates to do so.
As stated in [RFC6550] the DODAG Configuration option is present in As stated in [RFC6550] the DODAG Configuration option is present in
DIO messages. The DODAG Configuration option distributes DIO messages. The DODAG Configuration option distributes
configuration information. It is generally static, and does not configuration information. It is generally static, and does not
change within the DODAG. This information is configured at the DODAG change within the DODAG. This information is configured at the DODAG
root and distributed throughout the DODAG with the DODAG root and distributed throughout the DODAG with the DODAG
Configuration option. Nodes other than the DODAG root do not modify Configuration option. Nodes other than the DODAG root do not modify
this information when propagating the DODAG Configuration option. this information when propagating the DODAG Configuration option.
The DODAG Configuration Option has a Flag field which is modified by Currently, the DODAG Configuration Option in [RFC6550] states: "the
this document. Currently, the DODAG Configuration Option in unused bits MUST be initialize to zero by the sender and MUST be
[RFC6550] states: "the unused bits MUST be initialize to zero by the ignored by the receiver". If the flag is received with a value zero
sender and MUST be ignored by the receiver". (which is the default), then new nodes will remain in RFC6553
Compatible Mode; originating traffic with the old-RPI Option Type
(0x63) value. If the flag is received with a value of 1, then the
option value for the RPL Option MUST be set to 0x23.
Bit number three of the flag field in the DODAG Configuration option Bit number three of the flag field in the DODAG Configuration option
is to be used as shown in Figure 4 : is to be used as shown in Figure 4 :
+------------+-----------------+---------------+ +------------+-----------------+---------------+
| Bit number | Description | Reference | | Bit number | Description | Reference |
+------------+-----------------+---------------+ +------------+-----------------+---------------+
| 3 | RPI 0x23 enable | This document | | 3 | RPI 0x23 enable | This document |
+------------+-----------------+---------------+ +------------+-----------------+---------------+
Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag- Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-
day. day.
In case of rebooting, the node (6LN or 6LR) does not remember the RPL In case of rebooting, the node (6LN or 6LR) does not remember the RPI
Option Type, that is if the flag is set, so DIO messages sent by the Option Type, that is if the flag is set, so DIO messages sent by the
node would be set with the flag unset until a DIO message is received node would be set with the flag unset until a DIO message is received
with the flag set indicating the new RPI value. The node sets to with the flag set indicating the new RPI Option Type. The node sets
0x23 if the node supports this feature. to 0x23 if the node supports this feature.
4.4. Updates to RFC8138: Indicating the way to decompress with the new 4.4. Updates to RFC8138: Indicating the way to decompress with the new
RPI value. RPI Option Type.
This modification is required to be able to decompress the RPL RPI This modification is required to be able to decompress the RPL Option
option with the new value (0x23). with the new Option Type of 0x23.
RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138] RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]
in section 6. A node that is decompressing this header MUST in section 6. A node that is decompressing this header MUST
decompress using the RPL RPI option type that is currently active: decompress using the RPI Option Type that is currently active: that
that is, a choice between 0x23 (new) and 0x63 (old). The node will is, a choice between 0x23 (new) and 0x63 (old). The node will know
know which to use based upon the presence of the flag in the DODAG which to use based upon the presence of the flag in the DODAG
Configuration Option defined in Section 4.3. E.g. If the network is Configuration Option defined in Section 4.3. E.g. If the network is
in 0x23 mode (by DIO option), then it should be decompressed to 0x23. in 0x23 mode (by DIO option), then it should be decompressed to 0x23.
[RFC8138] section 7 documents how to compress the IPv6-in-IPv6 [RFC8138] section 7 documents how to compress the IPv6-in-IPv6
header. header.
There are potential significant advantages to having a single code There are potential significant advantages to having a single code
path that always processes IPv6-in-IPv6 headers with no conditional path that always processes IPv6-in-IPv6 headers with no conditional
branches. branches.
In Storing Mode, for the examples of Flow from RAL to RUL and RUL to In Storing Mode, for the examples of Flow from RAL to RUL and RUL to
RUL comprise an IPv6-in-IPv6 and RPI compression headers. The use of RUL comprise an IPv6-in-IPv6 and RPI compressed headers. The use of
the IPv6-in-IPv6 header is MANDATORY in this case, and it SHOULD be the IPv6-in-IPv6 header is MANDATORY in this case, and it SHOULD be
compressed with [RFC8138] section 7. Figure 5 illustrates the case compressed with [RFC8138] section 7. Figure 5 illustrates the case
in Storing mode where the packet is received from the Internet, then in Storing mode where the packet is received from the Internet, then
the root encapsulates the packet to insert the RPI. In that example, the root encapsulates the packet to insert the RPI. In that example,
the leaf is not known to support RFC 8138, and the packet is the leaf is not known to support RFC 8138, and the packet is
encapsulated to the 6LR that is the parent and last hop to the final encapsulated to the 6LR that is the parent and last hop to the final
destination. destination.
+-+ ... -+-+ ... +-+- ... -+-+- +-+-+-+ ... +-+-+ ... -+++ ... +-... +-+ ... -+-+ ... +-+- ... -+-+- +-+-+-+ ... +-+-+ ... -+++ ... +-...
|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
skipping to change at page 16, line 11 skipping to change at page 16, line 11
+-------+ +-------+ +------+ +-------+ +-------+ +-------+ +-------+ +------+ +-------+ +-------+
Figure 6: A reference RPL Topology. Figure 6: A reference RPL Topology.
6. Use cases 6. Use cases
In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6 In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6
encapsulation are going to be analyzed for a number of representative encapsulation are going to be analyzed for a number of representative
traffic flows. traffic flows.
This document assumes that the LLN is using the no-drop RPI option This document assumes that the LLN is using the no-drop RPI Option
(0x23). Type of 0x23.
The use cases describe the communication in the following cases: - The use cases describe the communication in the following cases: -
Between RPL-aware-nodes with the root (6LBR) - Between RPL-aware- Between RPL-aware-nodes with the root (6LBR) - Between RPL-aware-
nodes with the Internet - Between RUL nodes within the LLN (e.g. see nodes with the Internet - Between RUL nodes within the LLN (e.g. see
Section 7.1.4) - Inside of the LLN when the final destination address Section 7.1.4) - Inside of the LLN when the final destination address
resides outside of the LLN (e.g. see Section 7.2.3). resides outside of the LLN (e.g. see Section 7.2.3).
The uses cases are as follows: The uses cases are as follows:
Interaction between Leaf and Root: Interaction between Leaf and Root:
skipping to change at page 17, line 18 skipping to change at page 17, line 18
outlined in [RFC8200]. outlined in [RFC8200].
As the rank information in the RPI artifact is changed at each hop, As the rank information in the RPI artifact is changed at each hop,
it will typically be zero when it arrives at the DODAG root. The it will typically be zero when it arrives at the DODAG root. The
DODAG root MUST force it to zero when passing the packet out to the DODAG root MUST force it to zero when passing the packet out to the
Internet. The Internet will therefore not see any SenderRank Internet. The Internet will therefore not see any SenderRank
information. information.
Despite being legal to leave the RPI artifact in place, an Despite being legal to leave the RPI artifact in place, an
intermediate router that needs to add an extension header (e.g. RH3 intermediate router that needs to add an extension header (e.g. RH3
or RPI Option) MUST still encapsulate the packet in an (additional) or RPL Option) MUST still encapsulate the packet in an (additional)
outer IP header. The new header is placed after this new outer IP outer IP header. The new header is placed after this new outer IP
header. header.
A corollary is that an RH3 or RPI Option can only be removed by an A corollary is that an RH3 or RPL Option can only be removed by an
intermediate router if it is placed in an encapsulating IPv6 Header, intermediate router if it is placed in an encapsulating IPv6 Header,
which is addressed TO the intermediate router. When it does so, the which is addressed TO the intermediate router. When it does so, the
whole encapsulating header must be removed. (A replacement may be whole encapsulating header must be removed. (A replacement may be
added). This sometimes can result in outer IP headers being added). This sometimes can result in outer IP headers being
addressed to the next hop router using link-local address. addressed to the next hop router using link-local address.
Both RPI and RH3 headers may be modified in very specific ways by Both the RPL Option and the RH3 headers may be modified in very
routers on the path of the packet without the need to add and remove specific ways by routers on the path of the packet without the need
an encapsulating header. Both headers were designed with this to add and remove an encapsulating header. Both headers were
modification in mind, and both the RPL RH3 and the RPL option are designed with this modification in mind, and both the RPL RH3 and the
marked mutable but recoverable: so an IPsec AH security header can be RPL Option are marked mutable but recoverable: so an IPsec AH
applied across these headers, but it can not secure the values which security header can be applied across these headers, but it can not
mutate. secure the values which mutate.
RPI MUST be present in every single RPL data packet. The RPI MUST be present in every single RPL data packet.
Prior to [RFC8138], there was significant interest in removing the Prior to [RFC8138], there was significant interest in removing the
RPI for downward flows in non-storing mode. The exception covered a RPI for downward flows in non-storing mode. The exception covered a
very small number of cases, and causes significant interoperability very small number of cases, and causes significant interoperability
challenges, yet costed significant code and testing complexity. The challenges, yet costed significant code and testing complexity. The
ability to compress the RPI down to three bytes or less removes much ability to compress the RPI down to three bytes or less removes much
of the pressure to optimize this any further of the pressure to optimize this any further
[I-D.ietf-anima-autonomic-control-plane]. [I-D.ietf-anima-autonomic-control-plane].
The earlier examples are more extensive to make sure that the process The earlier examples are more extensive to make sure that the process
is clear, while later examples are more concise. is clear, while later examples are more concise.
The uses cases are delineated based on the following requirements: The uses cases are delineated based on the following requirements:
The RPI option has to be in every packet that traverses the LLN. The RPIhas to be in every packet that traverses the LLN.
- Because of the previous requirement, packets from the Internet - Because of the previous requirement, packets from the Internet
have to be encapsulated. have to be encapsulated.
- A Header cannot be inserted or removed on the fly inside an IPv6 - A Header cannot be inserted or removed on the fly inside an IPv6
packet that is being routed. packet that is being routed.
- Extension headers may not be added or removed except by the - Extension headers may not be added or removed except by the
sender or the receiver. sender or the receiver.
- RPI and RH3 headers may be modified by routers on the path of - RPI and RH3 headers may be modified by routers on the path of
the packet without the need to add and remove an encapsulating the packet without the need to add and remove an encapsulating
header. header.
- An RH3 or RPI Option can only be removed by an intermediate - An RH3 or RPL Option can only be removed by an intermediate
router if it is placed in an encapsulating IPv6 Header, which is router if it is placed in an encapsulating IPv6 Header, which is
addressed to the intermediate router. addressed to the intermediate router.
- Non-storing mode requires downstream encapsulation by root for - Non-storing mode requires downstream encapsulation by root for
RH3. RH3.
The uses cases are delineated based on the following assumptions: The uses cases are delineated based on the following assumptions:
This document assumes that the LLN is using the no-drop RPI option This document assumes that the LLN is using the no-drop RPI Option
(0x23). Type (0x23).
- Each IPv6 node (including Internet routers) obeys [RFC8200] RFC - Each IPv6 node (including Internet routers) obeys [RFC8200] RFC
8200, so that 0x23 RPI can be safely inserted. 8200, so that 0x23 RPI Option type can be safely inserted.
- All 6LRs obey RFC 8200 [RFC8200]. - All 6LRs obey RFC 8200 [RFC8200].
- The RPI is ignored at the IPv6 dst node (RUL). - The RPI is ignored at the IPv6 dst node (RUL).
- In the uses cases, we assume that the RAL supports IP-in-IP - In the uses cases, we assume that the RAL supports IP-in-IP
encapsulation. encapsulation.
- In the uses cases, we dont assume that the RUL supports IP-in-IP - In the uses cases, we dont assume that the RUL supports IP-in-IP
encapsulation. encapsulation.
skipping to change at page 19, line 23 skipping to change at page 19, line 23
each of the following scenarios. It indicates if the IPv6-in-IPv6 each of the following scenarios. It indicates if the IPv6-in-IPv6
header that is added, must be addressed to the final destination (the header that is added, must be addressed to the final destination (the
RAL node that is the target(tgt)), to the "root" or if a hop-by-hop RAL node that is the target(tgt)), to the "root" or if a hop-by-hop
header must be added (indicated by "hop"). In the hop-by-hop basis, header must be added (indicated by "hop"). In the hop-by-hop basis,
the destination address for the next hop is the link-layer address of the destination address for the next hop is the link-layer address of
the next hop. the next hop.
In cases where no IPv6-in-IPv6 header is needed, the column states as In cases where no IPv6-in-IPv6 header is needed, the column states as
"No". If the IPv6-in-IPv6 header is needed is a "must". "No". If the IPv6-in-IPv6 header is needed is a "must".
In all cases the RPI headers are needed, since it identifies In all cases the RPI is needed, since it identifies inconsistencies
inconsistencies (loops) in the routing topology. In all cases the (loops) in the routing topology. In all cases the RH3 is not needed
RH3 is not needed because it is not used in storing mode. because it is not used in storing mode.
In each case, 6LR_i are the intermediate routers from source to In each case, 6LR_i are the intermediate routers from source to
destination. "1 <= i <= n", n is the number of routers (6LR) that destination. "1 <= i <= n", n is the number of routers (6LR) that
the packet goes through from source (6LN) to destination. the packet goes through from source (6LN) to destination.
The leaf can be a router 6LR or a host, both indicated as 6LN. The The leaf can be a router 6LR or a host, both indicated as 6LN. The
root refers to the 6LBR (see Figure 6). root refers to the 6LBR (see Figure 6).
+---------------------+--------------+------------+------------------+ +---------------------+--------------+------------+------------------+
| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst | | Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |
skipping to change at page 21, line 17 skipping to change at page 21, line 17
In storing mode, RFC 6553 (RPI) is used to send RPL Information In storing mode, RFC 6553 (RPI) is used to send RPL Information
instanceID and rank information. instanceID and rank information.
In this case the flow comprises: In this case the flow comprises:
RAL (6LN) --> 6LR_i --> root(6LBR) RAL (6LN) --> 6LR_i --> root(6LBR)
For example, a communication flow could be: Node F --> Node D --> For example, a communication flow could be: Node F --> Node D -->
Node B --> Node A root(6LBR) Node B --> Node A root(6LBR)
The RAL (Node F) inserts the RPI header, and sends the packet to 6LR The RAL (Node F) inserts the RPI, and sends the packet to 6LR (Node
(Node D) which decrements the rank in RPI and sends the packet up. D) which decrements the rank in the RPI and sends the packet up.
When the packet arrives at 6LBR (Node A), the RPI is removed and the When the packet arrives at 6LBR (Node A), the RPI is removed and the
packet is processed. packet is processed.
No IPv6-in-IPv6 header is required. No IPv6-in-IPv6 header is required.
The RPI header can be removed by the 6LBR because the packet is The RPI can be removed by the 6LBR because the packet is addressed to
addressed to the 6LBR. The RAL must know that it is communicating the 6LBR. The RAL must know that it is communicating with the 6LBR
with the 6LBR to make use of this scenario. The RAL can know the to make use of this scenario. The RAL can know the address of the
address of the 6LBR because it knows the address of the root via the 6LBR because it knows the address of the root via the DODAGID in the
DODAGID in the DIO messages. DIO messages.
The Table 1 summarizes what headers are needed for this use case. The Table 1 summarizes what headers are needed for this use case.
+-------------------+---------+-------+----------+ +-------------------+---------+-------+----------+
| Header | RAL src | 6LR_i | 6LBR dst | | Header | RAL src | 6LR_i | 6LBR dst |
+-------------------+---------+-------+----------+ +-------------------+---------+-------+----------+
| Inserted headers | RPI | -- | -- | | Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI | | Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- | | Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- | | Modified headers | -- | RPI | -- |
skipping to change at page 22, line 4 skipping to change at page 22, line 4
Table 1: SM: Summary of the use of headers from RAL to root Table 1: SM: Summary of the use of headers from RAL to root
7.1.2. SM: Example of Flow from root to RAL 7.1.2. SM: Example of Flow from root to RAL
In this case the flow comprises: In this case the flow comprises:
root (6LBR) --> 6LR_i --> RAL (6LN) root (6LBR) --> 6LR_i --> RAL (6LN)
For example, a communication flow could be: Node A root(6LBR) --> For example, a communication flow could be: Node A root(6LBR) -->
Node B --> Node D --> Node F Node B --> Node D --> Node F
In this case the 6LBR inserts RPI header and sends the packet down, In this case the 6LBR inserts RPI and sends the packet down, the 6LR
the 6LR is going to increment the rank in RPI (it examines the is going to increment the rank in RPI (it examines the instanceID to
instanceID to identify the right forwarding table), the packet is identify the right forwarding table), the packet is processed in the
processed in the RAL and the RPI removed. RAL and the RPI removed.
No IPv6-in-IPv6 header is required. No IPv6-in-IPv6 header is required.
The Table 2 summarizes what headers are needed for this use case. The Table 2 summarizes what headers are needed for this use case.
+-------------------+----------+-------+---------+ +-------------------+----------+-------+---------+
| Header | 6LBR src | 6LR_i | RAL dst | | Header | 6LBR src | 6LR_i | RAL dst |
+-------------------+----------+-------+---------+ +-------------------+----------+-------+---------+
| Inserted headers | RPI | -- | -- | | Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI | | Removed headers | -- | -- | RPI |
skipping to change at page 23, line 15 skipping to change at page 23, line 15
7.1.4. SM: Example of Flow from RUL to root 7.1.4. SM: Example of Flow from RUL to root
In this case the flow comprises: In this case the flow comprises:
RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR)
For example, a communication flow could be: Node G --> Node E --> For example, a communication flow could be: Node G --> Node E -->
Node B --> Node A root(6LBR) Node B --> Node A root(6LBR)
When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E), When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
the 6LR_1 will insert a RPI header, encapsulated in a IPv6-in-IPv6 the 6LR_1 will insert a RPI, encapsulated in a IPv6-in-IPv6 header.
header. The IPv6-in-IPv6 header can be addressed to the next hop The IPv6-in-IPv6 header can be addressed to the next hop (Node B), or
(Node B), or to the root (Node A). The root removes the header and to the root (Node A). The root removes the header and processes the
processes the packet. packet.
The Figure 8 shows the table that summarizes what headers are needed The Figure 8 shows the table that summarizes what headers are needed
for this use case. [1] refers the case where the IPv6-in-IPv6 header for this use case. [1] refers the case where the IPv6-in-IPv6 header
is addressed to the next hop (Node B). [2] refers the case where the is addressed to the next hop (Node B). [2] refers the case where the
IPv6-in-IPv6 header is addressed to the root (Node A). IPv6-in-IPv6 header is addressed to the root (Node A).
+-----------+------+--------------+-----------------+------------------+ +-----------+------+--------------+-----------------+------------------+
| Header | RUL | 6LR_1 | 6LR_i | 6LBR dst | | Header | RUL | 6LR_1 | 6LR_i | 6LBR dst |
| | src | | | | | | src | | | |
| | node | | | | | | node | | | |
skipping to change at page 25, line 4 skipping to change at page 25, line 4
Table 4: SM: Summary of the use of headers from RAL to Internet Table 4: SM: Summary of the use of headers from RAL to Internet
7.2.2. SM: Example of Flow from Internet to RAL 7.2.2. SM: Example of Flow from Internet to RAL
In this case the flow comprises: In this case the flow comprises:
Internet --> root (6LBR) --> 6LR_i --> RAL (6LN) Internet --> root (6LBR) --> 6LR_i --> RAL (6LN)
For example, a communication flow could be: Internet --> Node A For example, a communication flow could be: Internet --> Node A
root(6LBR) --> Node B --> Node D --> Node F root(6LBR) --> Node B --> Node D --> Node F
When the packet arrives from Internet to 6LBR the RPI header is added When the packet arrives from Internet to 6LBR the RPI is added in a
in a outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination address
address set to the RAL) and sent to 6LR, which modifies the rank in set to the RAL) and sent to 6LR, which modifies the rank in the RPI.
the RPI. When the packet arrives at the RAL the RPI header is When the packet arrives at the RAL the RPI is removed and the packet
removed and the packet processed. processed.
The Figure 9 shows the table that summarizes what headers are needed The Figure 9 shows the table that summarizes what headers are needed
for this use case. for this use case.
+-----------+----------+--------------+--------------+--------------+ +-----------+----------+--------------+--------------+--------------+
| Header | Internet | 6LBR | 6LR_i | RAL dst | | Header | Internet | 6LBR | 6LR_i | RAL dst |
| | src | | | | | | src | | | |
+-----------+----------+--------------+--------------+--------------+ +-----------+----------+--------------+--------------+--------------+
| Inserted | -- | IP6-IP6(RPI) | -- | -- | | Inserted | -- | IP6-IP6(RPI) | -- | -- |
| headers | | | | | | headers | | | | |
skipping to change at page 25, line 46 skipping to change at page 25, line 46
In this case the flow comprises: In this case the flow comprises:
RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet
For example, a communication flow could be: Node G --> Node E --> For example, a communication flow could be: Node G --> Node E -->
Node B --> Node A root(6LBR) --> Internet Node B --> Node A root(6LBR) --> Internet
The 6LR_1 (i=1) node will add an IPv6-in-IPv6(RPI) header addressed The 6LR_1 (i=1) node will add an IPv6-in-IPv6(RPI) header addressed
either to the root, or hop-by-hop such that the root can remove the either to the root, or hop-by-hop such that the root can remove the
RPI header before passing upwards. The IPv6-in-IPv6 addressed to the RPI before passing upwards. The IPv6-in-IPv6 addressed to the root
root cause less processing overhead. On the other hand, with hop-by- cause less processing overhead. On the other hand, with hop-by-hop
hop the intermediate routers can check the routing tables for a the intermediate routers can check the routing tables for a better
better routing path, thus it could be more efficient and faster. routing path, thus it could be more efficient and faster.
Implementation should decide which approach to take. Implementation should decide which approach to take.
The originating node will ideally leave the IPv6 flow label as zero The originating node will ideally leave the IPv6 flow label as zero
so that the packet can be better compressed through the LLN. The so that the packet can be better compressed through the LLN. The
6LBR will set the flow label of the packet to a non-zero value when 6LBR will set the flow label of the packet to a non-zero value when
sending to the Internet, for details check [RFC6437]. sending to the Internet, for details check [RFC6437].
The Figure 10 shows the table that summarizes what headers are needed The Figure 10 shows the table that summarizes what headers are needed
for this use case. In the table, [1] shows the case when packet is for this use case. In the table, [1] shows the case when packet is
addressed to the root. [2] shows the case when the packet is addressed to the root. [2] shows the case when the packet is
skipping to change at page 26, line 48 skipping to change at page 26, line 48
7.2.4. SM: Example of Flow from Internet to RUL. 7.2.4. SM: Example of Flow from Internet to RUL.
In this case the flow comprises: In this case the flow comprises:
Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
For example, a communication flow could be: Internet --> Node A For example, a communication flow could be: Internet --> Node A
root(6LBR) --> Node B --> Node E --> Node G root(6LBR) --> Node B --> Node E --> Node G
The 6LBR will have to add an RPI header within an IPv6-in-IPv6 The 6LBR will have to add an RPI within an IPv6-in-IPv6 header. The
header. The IPv6-in-IPv6 is addressed to the 6LR parent of the IPv6-in-IPv6 is addressed to the 6LR parent of the 6lR_i.
6lR_i.
Further details about this are mentioned in Further details about this are mentioned in
[I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN [I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN
acting as a plain host and not being aware of RPL. acting as a plain host and not being aware of RPL.
The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to
zero in order to aid in compression [RFC8138][RFC6437]. zero in order to aid in compression [RFC8138][RFC6437].
The Figure 11 shows the table that summarizes what headers are needed The Figure 11 shows the table that summarizes what headers are needed
for this use case. for this use case.
skipping to change at page 30, line 44 skipping to change at page 30, line 44
G) to the common parent (6LR_x) (Node B). In this case, 1 <= ia <= G) to the common parent (6LR_x) (Node B). In this case, 1 <= ia <=
n, n is the number of routers (6LR) that the packet goes through from n, n is the number of routers (6LR) that the packet goes through from
source to the common parent. source to the common parent.
6LR_id (Node D) are the intermediate routers from the common parent 6LR_id (Node D) are the intermediate routers from the common parent
(6LR_x) (Node B) to destination RAL (Node F). In this case, 1 <= id (6LR_x) (Node B) to destination RAL (Node F). In this case, 1 <= id
<= m, m is the number of routers (6LR) that the packet goes through <= m, m is the number of routers (6LR) that the packet goes through
from the common parent (6LR_x) to the destination RAL. from the common parent (6LR_x) to the destination RAL.
The 6LR_ia (ia=1) (Node E) receives the packet from the RUL (Node G) The 6LR_ia (ia=1) (Node E) receives the packet from the RUL (Node G)
and inserts the RPI header encapsulated in a IPv6-in-IPv6 header. and inserts the RPI encapsulated in a IPv6-in-IPv6 header. The IPv6-
The IPv6-in-IPv6 header is addressed to the destination RAL (Node F). in-IPv6 header is addressed to the destination RAL (Node F).
The Figure 12 shows the table that summarizes what headers are needed The Figure 12 shows the table that summarizes what headers are needed
for this use case. for this use case.
+---------+-----+------------+-------------+-------------+------------+ +---------+-----+------------+-------------+-------------+------------+
| Header |RUL | 6LR_ia | Common | 6LR_id | RAL | | Header |RUL | 6LR_ia | Common | 6LR_id | RAL |
| |src | | Parent | | dst | | |src | | Parent | | dst |
| |node | | (6LRx) | | | | |node | | (6LRx) | | |
+---------+-----+------------+-------------+-------------+------------+ +---------+-----+------------+-------------+-------------+------------+
| Inserted| -- |IP6-IP6(RPI)| -- | -- | -- | | Inserted| -- |IP6-IP6(RPI)| -- | -- | -- |
skipping to change at page 31, line 51 skipping to change at page 31, line 51
packet goes through from the RUL to the root. packet goes through from the RUL to the root.
6LR_id (Node C) are the intermediate routers from the root (Node A) 6LR_id (Node C) are the intermediate routers from the root (Node A)
to the destination RUL dst node (Node J). In this case, 1 <= id <= to the destination RUL dst node (Node J). In this case, 1 <= id <=
m, m is the number of routers (6LR) that the packet goes through from m, m is the number of routers (6LR) that the packet goes through from
the root to destination RUL. the root to destination RUL.
The RPI is ignored at the RUL dst node. The RPI is ignored at the RUL dst node.
The 6LR_1 (Node E) receives the packet from the RUL (Node G) and The 6LR_1 (Node E) receives the packet from the RUL (Node G) and
inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6 header inserts the RPI (RPI), encapsulated in an IPv6-in-IPv6 header
directed to the root. The root removes the RPI and inserts a new RPI directed to the root. The root removes the RPI and inserts a new RPI
header addressed to the 6LR father of the RUL. addressed to the 6LR father of the RUL.
The Figure 13 shows the table that summarizes what headers are needed The Figure 13 shows the table that summarizes what headers are needed
for this use case. for this use case.
+---------+------+-------+-------+---------+-------+-------+ +---------+------+-------+-------+---------+-------+-------+
| Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | RUL | | Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | RUL |
| | src | | | | | dst | | | src | | | | | dst |
| | node | | | | | node | | | node | | | | | node |
+---------+------+-------+-------+---------+-------+-------+ +---------+------+-------+-------+---------+-------+-------+
| Inserted| -- |IP6-IP6|IP6-IP6| IP6-IP6 |IP6-IP6| -- | | Inserted| -- |IP6-IP6|IP6-IP6| IP6-IP6 |IP6-IP6| -- |
skipping to change at page 33, line 10 skipping to change at page 33, line 10
header are to be inserted. It depicts the target destination address header are to be inserted. It depicts the target destination address
possible to a 6LN (indicated by "RAL"), to a 6LR (parent of a 6LN) or possible to a 6LN (indicated by "RAL"), to a 6LR (parent of a 6LN) or
to the root. In cases where no IPv6-in-IPv6 header is needed, the to the root. In cases where no IPv6-in-IPv6 header is needed, the
column states as "No". There is no expectation on RPL that RPI can column states as "No". There is no expectation on RPL that RPI can
be omitted, because it is needed for routing, quality of service and be omitted, because it is needed for routing, quality of service and
compression. This specification expects that is always a RPI compression. This specification expects that is always a RPI
Present. Present.
The leaf can be a router 6LR or a host, both indicated as 6LN The leaf can be a router 6LR or a host, both indicated as 6LN
(Figure 6). In the table (Figure 14) the (1) indicates a 6tisch case (Figure 6). In the table (Figure 14) the (1) indicates a 6tisch case
[RFC8180], where the RPI header may still be needed for the [RFC8180], where the RPI may still be needed for the instanceID to be
instanceID to be available for priority/channel selection at each available for priority/channel selection at each hop.
hop.
+-----------------+--------------+-----+-----+------------+------------+ +-----------------+--------------+-----+-----+------------+------------+
| Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6| | Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6|
| between | | | | | dst | | between | | | | | dst |
+-----------------+--------------+-----+-----+------------+------------+ +-----------------+--------------+-----+-----+------------+------------+
| | RAL to root | Yes | No | No | No | | | RAL to root | Yes | No | No | No |
+ +--------------+-----+-----+------------+------------+ + +--------------+-----+-----+------------+------------+
| Leaf - Root | root to RAL | Yes | Yes | No | No | | Leaf - Root | root to RAL | Yes | Yes | No | No |
+ +--------------+-----+-----+------------+------------+ + +--------------+-----+-----+------------+------------+
| | root to RUL | Yes | Yes | must | 6LR | | | root to RUL | Yes | Yes | must | 6LR |
skipping to change at page 34, line 4 skipping to change at page 33, line 50
| | RUL to RUL | Yes | Yes | must | root/6LR | | | RUL to RUL | Yes | Yes | must | root/6LR |
+-----------------+--------------+-----+-----+------------+------------+ +-----------------+--------------+-----+-----+------------+------------+
Figure 14: Table that shows headers needed in Non-Storing mode: RPI, Figure 14: Table that shows headers needed in Non-Storing mode: RPI,
RH3, IPv6-in-IPv6 encapsulation. RH3, IPv6-in-IPv6 encapsulation.
8.1. Non-Storing Mode: Interaction between Leaf and Root 8.1. Non-Storing Mode: Interaction between Leaf and Root
In this section is described the communication flow in Non Storing In this section is described the communication flow in Non Storing
Mode (Non-SM) between, Mode (Non-SM) between,
RAL to root
RAL to root
root to RAL root to RAL
RUL to root RUL to root
root to RUL root to RUL
8.1.1. Non-SM: Example of Flow from RAL to root 8.1.1. Non-SM: Example of Flow from RAL to root
In non-storing mode the leaf node uses default routing to send In non-storing mode the leaf node uses default routing to send
traffic to the root. The RPI header must be included since it traffic to the root. The RPI must be included since it contains the
contains the rank information, which is used to avoid/detect loops. rank information, which is used to avoid/detect loops.
RAL (6LN) --> 6LR_i --> root(6LBR) RAL (6LN) --> 6LR_i --> root(6LBR)
For example, a communication flow could be: Node F --> Node D --> For example, a communication flow could be: Node F --> Node D -->
Node B --> Node A (root) Node B --> Node A (root)
6LR_i are the intermediate routers from source to destination. In 6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i <= n", n is the number of routers (6LR) that the this case, "1 <= i <= n", n is the number of routers (6LR) that the
packet goes through from source (RAL) to destination (6LBR). packet goes through from source (RAL) to destination (6LBR).
skipping to change at page 35, line 8 skipping to change at page 35, line 8
In this case the flow comprises: In this case the flow comprises:
root (6LBR) --> 6LR_i --> RAL (6LN) root (6LBR) --> 6LR_i --> RAL (6LN)
For example, a communication flow could be: Node A (root) --> Node B For example, a communication flow could be: Node A (root) --> Node B
--> Node D --> Node F --> Node D --> Node F
6LR_i are the intermediate routers from source to destination. In 6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i <= n", n is the number of routers (6LR) that the this case, "1 <= i <= n", n is the number of routers (6LR) that the
packet goes through from source (6LBR) to destination (RAL). packet goes through from source (6LBR) to destination (RAL).
The 6LBR inserts an RH3, and a RPI header. No IPv6-in-IPv6 header is The 6LBR inserts an RH3, and a RPI. No IPv6-in-IPv6 header is
necessary as the traffic originates with an RPL aware node, the 6LBR. necessary as the traffic originates with an RPL aware node, the 6LBR.
The destination is known to be RPL-aware because the root knows the The destination is known to be RPL-aware because the root knows the
whole topology in non-storing mode. whole topology in non-storing mode.
The Table 8 summarizes what headers are needed for this use case. The Table 8 summarizes what headers are needed for this use case.
+-------------------+----------+-----------+-----------+ +-------------------+----------+-----------+-----------+
| Header | 6LBR src | 6LR_i | RAL dst | | Header | 6LBR src | 6LR_i | RAL dst |
+-------------------+----------+-----------+-----------+ +-------------------+----------+-----------+-----------+
| Inserted headers | RPI, RH3 | -- | -- | | Inserted headers | RPI, RH3 | -- | -- |
skipping to change at page 39, line 39 skipping to change at page 39, line 39
For example, a communication flow could be: Node G --> Node E --> For example, a communication flow could be: Node G --> Node E -->
Node B --> Node A --> Internet Node B --> Node A --> Internet
6LR_i are the intermediate routers from source to destination. In 6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i <= n", n is the number of routers (6LR) that the this case, "1 <= i <= n", n is the number of routers (6LR) that the
packet goes through from source (RUL) to 6LBR, e.g. 6LR_1 (i=1). packet goes through from source (RUL) to 6LBR, e.g. 6LR_1 (i=1).
In this case the flow label is recommended to be zero in the IPv6 In this case the flow label is recommended to be zero in the IPv6
node. As RPL headers are added in the IPv6 node packet, the first node. As RPL headers are added in the IPv6 node packet, the first
6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header. 6LR (6LR_1) will add a RPI inside a new IPv6-in-IPv6 header. The
The IPv6-in-IPv6 header will be addressed to the root. This case is IPv6-in-IPv6 header will be addressed to the root. This case is
identical to the storing-mode case (see Section 7.2.3). identical to the storing-mode case (see Section 7.2.3).
The Figure 17 shows the table that summarizes what headers are needed The Figure 17 shows the table that summarizes what headers are needed
for this use case. for this use case.
+---------+----+-------------+--------------+--------------+--------+ +---------+----+-------------+--------------+--------------+--------+
| Header |RUL | 6LR_1 | 6LR_i | 6LBR |Internet| | Header |RUL | 6LR_1 | 6LR_i | 6LBR |Internet|
| |src | | [i=2,..,n] | | dst | | |src | | [i=2,..,n] | | dst |
| |node| | | | | | |node| | | | |
+---------+----+-------------+--------------+--------------+--------+ +---------+----+-------------+--------------+--------------+--------+
skipping to change at page 42, line 13 skipping to change at page 42, line 13
Node B --> Node A (root) --> Node B --> Node E --> Node H Node B --> Node A (root) --> Node B --> Node E --> Node H
6LR_ia are the intermediate routers from source to the root In this 6LR_ia are the intermediate routers from source to the root In this
case, 1 <= ia <= n, n is the number of routers (6LR) that the packet case, 1 <= ia <= n, n is the number of routers (6LR) that the packet
goes through from RAL to the root. goes through from RAL to the root.
6LR_id are the intermediate routers from the root to the destination. 6LR_id are the intermediate routers from the root to the destination.
In this case, "1 <= ia <= m", m is the number of the intermediate In this case, "1 <= ia <= m", m is the number of the intermediate
routers (6LR). routers (6LR).
This case involves only nodes in same RPL Domain. The originating This case involves only nodes in same RPL Domain. The originating
node will add a RPI header to the original packet, and send the node will add a RPI to the original packet, and send the packet
packet upwards. upwards.
The originating node must put the RPI (RPI1) into an IPv6-in-IPv6 The originating node must put the RPI (RPI1) into an IPv6-in-IPv6
header addressed to the root, so that the 6LBR can remove that header addressed to the root, so that the 6LBR can remove that
header. If it does not, then additional resources are wasted on the header. If it does not, then additional resources are wasted on the
way down to carry the useless RPI option. way down to carry the useless RPI.
The 6LBR will need to insert an RH3 header, which requires that it The 6LBR will need to insert an RH3 header, which requires that it
add an IPv6-in-IPv6 header. It should be able to remove the add an IPv6-in-IPv6 header. It should be able to remove the
RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to
it. Otherwise, there may be a RPI header buried inside the inner IP it. Otherwise, there may be a RPI buried inside the inner IP header,
header, which should get ignored. The root inserts a RPI (RPI2) which should get ignored. The root inserts a RPI (RPI2) alongside
alongside the RH3. the RH3.
Networks that use the RPL P2P extension [RFC6997] are essentially Networks that use the RPL P2P extension [RFC6997] are essentially
non-storing DODAGs and fall into this scenario or scenario non-storing DODAGs and fall into this scenario or scenario
Section 8.1.2, with the originating node acting as 6LBR. Section 8.1.2, with the originating node acting as 6LBR.
The Figure 19 shows the table that summarizes what headers are needed The Figure 19 shows the table that summarizes what headers are needed
for this use case. for this use case.
+---------+------------+----------+------------+----------+------------+ +---------+------------+----------+------------+----------+------------+
| Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL | | Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL |
skipping to change at page 47, line 43 skipping to change at page 47, line 43
could otherwise omit this unnecessary header if it was certain of the could otherwise omit this unnecessary header if it was certain of the
properties of the leaf. properties of the leaf.
As storing mode can not know the final path of the traffic, As storing mode can not know the final path of the traffic,
intolerant (that drop packets with RPL artifacts) leaf nodes can not intolerant (that drop packets with RPL artifacts) leaf nodes can not
be supported. be supported.
10. Operational considerations of introducing 0x23 10. Operational considerations of introducing 0x23
This section describes the operational considerations of introducing This section describes the operational considerations of introducing
the new RPI value of 0x23. the new RPI Option Type of 0x23.
During bootstrapping the node gets the DIO with the information of During bootstrapping the node gets the DIO with the information of
RPL Option Type, indicating the new RPI in the DODAG Configuration RPI Option Type, indicating the new RPI in the DODAG Configuration
Option Flag. The DODAG root is in charge to configure the current Option Flag. The DODAG root is in charge to configure the current
network to the new value, through DIO messages and when all the nodes network to the new value, through DIO messages and when all the nodes
are set with the new value. The DODAG should change to a new DODAG are set with the new value. The DODAG should change to a new DODAG
version. In case of rebooting, the node does not remember the RPL version. In case of rebooting, the node does not remember the RPI
Option Type. Thus, the DIO is sent with a flag indicating the new Option Type. Thus, the DIO is sent with a flag indicating the new
RPI value. RPI Option Type.
The DODAG Configuration option is contained in a RPL DIO message, The DODAG Configuration option is contained in a RPL DIO message,
which contains a unique DTSN counter. The leaf nodes respond to this which contains a unique DTSN counter. The leaf nodes respond to this
message with DAO messages containing the same DTSN. This is a normal message with DAO messages containing the same DTSN. This is a normal
part of RPL routing; the RPL root therefore knows when the updated part of RPL routing; the RPL root therefore knows when the updated
DODAG Configuration Option has been seen by all nodes. DODAG Configuration Option has been seen by all nodes.
Before the migration happens, all the RPL-aware nodes should support Before the migration happens, all the RPL-aware nodes should support
both values . The migration procedure it is triggered when the DIO both values . The migration procedure it is triggered when the DIO
is sent with the flag indicating the new RPI value. Namely, it is sent with the flag indicating the new RPI Option Type. Namely, it
remains at 0x63 until it is sure that the network is capable of 0x23, remains at 0x63 until it is sure that the network is capable of 0x23,
then it abruptly change to 0x23. This options allows to send packets then it abruptly change to 0x23. This options allows to send packets
to not-RPL nodes, which should ignore the option and continue to not-RPL nodes, which should ignore the option and continue
processing the packets. processing the packets.
In case that a node join to a network that only process 0x63, it In case that a node join to a network that only process 0x63, it
would produce a flag day as was mentioned previously. Indicating the would produce a flag day as was mentioned previously. Indicating the
new RPI in the DODAG Configuration Option Flag is a way to avoid the new RPI in the DODAG Configuration Option Flag is a way to avoid the
flag day in a network. It is recommended that a network process both flag day in a network. It is recommended that a network process both
options to enable interoperability. options to enable interoperability.
skipping to change at page 51, line 14 skipping to change at page 51, line 14
if the RH3 header has not been completely consumed. A consumed if the RH3 header has not been completely consumed. A consumed
(inert) RH3 header could be present in a packet that flows from one (inert) RH3 header could be present in a packet that flows from one
LLN, crosses the Internet, and enters another LLN. As per the LLN, crosses the Internet, and enters another LLN. As per the
discussion in this document, such headers do not need to be removed. discussion in this document, such headers do not need to be removed.
However, there is no case described in this document where an RH3 is However, there is no case described in this document where an RH3 is
inserted in a non-storing network on traffic that is leaving the LLN, inserted in a non-storing network on traffic that is leaving the LLN,
but this document should not preclude such a future innovation. It but this document should not preclude such a future innovation. It
should just be noted that an incoming RH3 must be fully consumed, or should just be noted that an incoming RH3 must be fully consumed, or
very carefully inspected. very carefully inspected.
The RPI header, if permitted to enter the LLN, could be used by an The RPI, if permitted to enter the LLN, could be used by an attacker
attacker to change the priority of a packet by selecting a different to change the priority of a packet by selecting a different
RPLInstanceID, perhaps one with a higher energy cost, for instance. RPLInstanceID, perhaps one with a higher energy cost, for instance.
It could also be that not all nodes are reachable in an LLN using the It could also be that not all nodes are reachable in an LLN using the
default instanceID, but a change of instanceID would permit an default instanceID, but a change of instanceID would permit an
attacker to bypass such filtering. Like the RH3, a RPI header is to attacker to bypass such filtering. Like the RH3, a RPI is to be
be inserted by the RPL root on traffic entering the LLN by first inserted by the RPL root on traffic entering the LLN by first
inserting an IPv6-in-IPv6 header. The attacker's RPI header inserting an IPv6-in-IPv6 header. The attacker's RPI therefore will
therefore will not be seen by the network. Upon reaching the not be seen by the network. Upon reaching the destination node the
destination node the RPI header has no further meaning and is just RPI has no further meaning and is just skipped; the presence of a
skipped; the presence of a second RPI header will have no meaning to second RPI will have no meaning to the end node as the packet has
the end node as the packet has already been identified as being at already been identified as being at it's final destination.
it's final destination.
The RH3 and RPI headers could be abused by an attacker inside of the The RH3 and RPIs could be abused by an attacker inside of the network
network to route packets on non-obvious ways, perhaps eluding to route packets on non-obvious ways, perhaps eluding observation.
observation. This usage is in fact part of [RFC6997] and can not be This usage is in fact part of [RFC6997] and can not be restricted at
restricted at all. This is a feature, not a bug. all. This is a feature, not a bug.
[RFC7416] deals with many other threats to LLNs not directly related [RFC7416] deals with many other threats to LLNs not directly related
to the use of IPv6-in-IPv6 headers, and this document does not change to the use of IPv6-in-IPv6 headers, and this document does not change
that analysis. that analysis.
Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an
attack on another part of the LLN, while disguising the origin of the attack on another part of the LLN, while disguising the origin of the
attack. The mechanism can even be abused to make it appear that the attack. The mechanism can even be abused to make it appear that the
attack is coming from outside the LLN, and unless countered, this attack is coming from outside the LLN, and unless countered, this
could be used to mount a Distributed Denial Of Service attack upon could be used to mount a Distributed Denial Of Service attack upon
skipping to change at page 54, line 45 skipping to change at page 54, line 41
in progress), September 2019. in progress), September 2019.
[I-D.ietf-6tisch-dtsecurity-secure-join] [I-D.ietf-6tisch-dtsecurity-secure-join]
Richardson, M., "6tisch Secure Join protocol", draft-ietf- Richardson, M., "6tisch Secure Join protocol", draft-ietf-
6tisch-dtsecurity-secure-join-01 (work in progress), 6tisch-dtsecurity-secure-join-01 (work in progress),
February 2017. February 2017.
[I-D.ietf-anima-autonomic-control-plane] [I-D.ietf-anima-autonomic-control-plane]
Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
Control Plane (ACP)", draft-ietf-anima-autonomic-control- Control Plane (ACP)", draft-ietf-anima-autonomic-control-
plane-20 (work in progress), July 2019. plane-21 (work in progress), November 2019.
[I-D.ietf-anima-bootstrapping-keyinfra] [I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Eckert, T., Behringer, M., Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
keyinfra-29 (work in progress), October 2019. keyinfra-30 (work in progress), November 2019.
[I-D.ietf-intarea-tunnels] [I-D.ietf-intarea-tunnels]
Touch, J. and M. Townsley, "IP Tunnels in the Internet Touch, J. and M. Townsley, "IP Tunnels in the Internet
Architecture", draft-ietf-intarea-tunnels-10 (work in Architecture", draft-ietf-intarea-tunnels-10 (work in
progress), September 2019. progress), September 2019.
[I-D.ietf-roll-unaware-leaves] [I-D.ietf-roll-unaware-leaves]
Thubert, P. and M. Richardson, "Routing for RPL Leaves", Thubert, P. and M. Richardson, "Routing for RPL Leaves",
draft-ietf-roll-unaware-leaves-06 (work in progress), draft-ietf-roll-unaware-leaves-07 (work in progress),
November 2019. November 2019.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <https://www.rfc-editor.org/info/rfc2460>. December 1998, <https://www.rfc-editor.org/info/rfc2460>.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
December 1998, <https://www.rfc-editor.org/info/rfc2473>. December 1998, <https://www.rfc-editor.org/info/rfc2473>.
skipping to change at page 56, line 24 skipping to change at page 56, line 24
May 2017, <https://www.rfc-editor.org/info/rfc8180>. May 2017, <https://www.rfc-editor.org/info/rfc8180>.
[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>.
Authors' Addresses Authors' Addresses
Maria Ines Robles Maria Ines Robles
Aalto University, Finland - / - Universidad Tecnologica Nacional - Facultad Regional Mendoza, Argentina Aalto University, Finland
Email: mariainesrobles@gmail.com Email: mariainesrobles@gmail.com
Michael C. Richardson Michael C. Richardson
Sandelman Software Works Sandelman Software Works
470 Dawson Avenue 470 Dawson Avenue
Ottawa, ON K1Z 5V7 Ottawa, ON K1Z 5V7
CA CA
Email: mcr+ietf@sandelman.ca Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/mcr/ URI: http://www.sandelman.ca/mcr/
 End of changes. 82 change blocks. 
182 lines changed or deleted 191 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/