draft-ietf-roll-turnon-rfc8138-18.txt   rfc9035.txt 
ROLL P. Thubert, Ed. Internet Engineering Task Force (IETF) P. Thubert, Ed.
Internet-Draft L. Zhao Request for Comments: 9035 L. Zhao
Updates: 8138 (if approved) Cisco Systems Updates: 8138 Cisco Systems
Intended status: Standards Track 18 December 2020 Category: Standards Track April 2021
Expires: 21 June 2021 ISSN: 2070-1721
A RPL DODAG Configuration Option for the 6LoWPAN Routing Header A Routing Protocol for Low-Power and Lossy Networks (RPL)
draft-ietf-roll-turnon-rfc8138-18 Destination-Oriented Directed Acyclic Graph (DODAG) Configuration Option
for the 6LoWPAN Routing Header
Abstract Abstract
This document updates RFC 8138 by defining a bit in the RPL DODAG This document updates RFC 8138 by defining a bit in the Routing
Configuration Option to indicate whether compression is used within Protocol for Low-Power and Lossy Networks (RPL) Destination-Oriented
the RPL Instance, and specify the behavior of RFC 8138-capable nodes Directed Acyclic Graph (DODAG) Configuration option to indicate
when the bit is set and unset. whether compression is used within the RPL Instance and to specify
the behavior of nodes compliant with RFC 8138 when the bit is set and
unset.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 21 June 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9035.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology
2.1. References . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Related Documents
2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Glossary
2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.3. Requirements Language
3. Extending RFC 6550 . . . . . . . . . . . . . . . . . . . . . 4 3. Extending RFC 6550
4. Updating RFC 8138 . . . . . . . . . . . . . . . . . . . . . . 5 4. Updating RFC 8138
5. Transition Scenarios . . . . . . . . . . . . . . . . . . . . 5 5. Transition Scenarios
5.1. Coexistence . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Coexistence
5.2. Inconsistent State While Migrating . . . . . . . . . . . 6 5.2. Inconsistent State While Migrating
5.3. Rolling Back . . . . . . . . . . . . . . . . . . . . . . 6 5.3. Rolling Back
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. References
9. Normative References . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References
10. Informative References . . . . . . . . . . . . . . . . . . . 9 8.2. Informative References
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Acknowledgments
Authors' Addresses
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low-Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, which is the most constrained resource of
all. The routing optimizations in the "Routing Protocol for Low all. The routing optimizations in "RPL: IPv6 Routing Protocol for
Power and Lossy Networks" [RFC6550] (RPL) such as routing along a Low-Power and Lossy Networks" [RFC6550], such as routing along a
Destination-Oriented Directed Acyclic Graph (DODAG) to a Root Node Destination-Oriented Directed Acyclic Graph (DODAG) to a Root Node
and the associated routing header compression and forwarding and the associated routing header compression and forwarding
technique specified in [RFC8138] derive from that primary concern. technique specified in [RFC8138], derive from that primary concern.
Enabling [RFC8138] on a running network requires a Flag Day where the Enabling [RFC8138] on a running network requires a "flag day", where
network is upgraded and rebooted. Otherwise, if acting as a Leaf, a the network is upgraded and rebooted. Otherwise, if acting as a
node that does not support the compression would fail to communicate; leaf, a node that does not support compression per [RFC8138] would
if acting as a router it would drop the compressed packets and black- fail to communicate; if acting as a router, it would drop the
hole a portion of the network. This specification enables a hot compressed packets and black-hole a portion of the network. This
upgrade where a live network is migrated. During the migration, the specification enables a hot upgrade where a live network is migrated.
compression remains inactive, until all nodes are upgraded. During the migration, compression remains inactive until all nodes
are upgraded.
This document complements [RFC8138] and signals whether it should be This document complements [RFC8138] and signals whether it should be
used within a RPL DODAG with a new flag in the RPL DODAG used within a RPL DODAG with a new flag in the RPL DODAG
Configuration Option. The setting of this new flag is controlled by Configuration option. The setting of this new flag is controlled by
the Root and propagates as is in the whole network as part of the the Root and propagates as is in the whole network as part of the
normal RPL signaling. normal RPL signaling.
The flag is cleared to maintain the compression inactive during the The flag is cleared to ensure that compression remains inactive
migration phase. When the migration is complete (e.g., as known by during the migration phase. When the migration is complete (e.g., as
network management and/or inventory), the flag is set and the known by network management and/or inventory), the flag is set and
compression is globally activated in the whole DODAG. compression is globally activated in the whole DODAG.
2. Terminology 2. Terminology
2.1. References 2.1. Related Documents
The terminology used in this document is consistent with and The terminology used in this document is consistent with, and
incorporates that described in "Terms Used in Routing for Low-Power incorporates the terms provided in, "Terms Used in Routing for
and Lossy Networks (LLNs)" [RFC7102]. Other terms in use in LLNs are Low-Power and Lossy Networks" [RFC7102]. Other terms in use as
found in "Terminology for Constrained-Node Networks" [RFC7228]. related to LLNs are found in "Terminology for Constrained-Node
Networks" [RFC7228].
"RPL", the "RPL Packet Information" (RPI), and "RPL Instance" "RPL", "RPL Packet Information" (RPI), and "RPL Instance" (indexed by
(indexed by a RPLInstanceID) are defined in "RPL: IPv6 Routing a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for
Protocol for Low-Power and Lossy Networks" [RFC6550]. The RPI is the Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract
abstract information that RPL defines to be placed in data packets, information that RPL defines to be placed in data packets, e.g., as
e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By
By extension the term "RPI" is often used to refer to the RPL Option extension, the term "RPI" is often used to refer to the RPL Option
itself. The DODAG Information Solicitation (DIS), Destination itself. The DODAG Information Solicitation (DIS), Destination
Advertisement Object (DAO) and DODAG Information Object (DIO) Advertisement Object (DAO), and DODAG Information Object (DIO)
messages are also specified in [RFC6550]. messages are also specified in [RFC6550].
This document uses the terms RPL-Unaware Leaf (RUL) and RPL-Aware This document uses the terms "RPL-Unaware Leaf" (RUL) and "RPL-Aware
Leaf (RAL) consistently with "Using RPI Option Type, Routing Header Leaf" (RAL) consistently with "Using RPI Option Type, Routing Header
for Source Routes and IPv6-in-IPv6 encapsulation in the RPL Data for Source Routes, and IPv6-in-IPv6 Encapsulation in the RPL Data
Plane" [USEofRPLinfo]. The term RPL-Aware Node (RAN) refers to a Plane" [RFC9008]. The term "RPL-Aware Node" (RAN) refers to a node
node that is either a RAL or a RPL Router. A RAN manages the that is either a RAL or a RPL router. A RAN manages the reachability
reachability of its addresses and prefixes by injecting them in RPL of its addresses and prefixes by injecting them in RPL by itself. In
by itself. In contrast, a RUL leverages "Registration Extensions for contrast, a RUL leverages "Registration Extensions for IPv6 over
IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery" [RFC8505] to obtain reachability services from its parent Discovery" [RFC8505] to obtain reachability services from its parent
router(s) as specified in "Routing for RPL Leaves" [UNAWARE-LEAVES]. router(s) as specified in "Routing for RPL (Routing Protocol for
Low-Power and Lossy Networks) Leaves" [RFC9010].
2.2. Glossary 2.2. Glossary
This document often uses the following acronyms: This document often uses the following abbreviations:
6LoWPAN: IPv6 over Low-Power Wireless Personal Area Network
6LoRH: 6LoWPAN Routing Header 6LoRH: 6LoWPAN Routing Header
6LoWPAN: IPv6 over Low-Power Wireless Personal Area Network
DIO: DODAG Information Object (a RPL message) DIO: DODAG Information Object (a RPL message)
DODAG: Destination-Oriented Directed Acyclic Graph DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks
SubDAG: A DODAG rooted at a node which is a child of that node and a
subset of a larger DAG
MOP: RPL Mode of Operation MOP: RPL Mode of Operation
RPI: RPL Packet Information
RAL: RPL-Aware Leaf RAL: RPL-Aware Leaf
RAN: RPL-Aware Node RAN: RPL-Aware Node
RPI: RPL Packet Information
RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks
RUL: RPL-Unaware Leaf RUL: RPL-Unaware Leaf
SRH: Source Routing Header SRH: Source Routing Header
Sub-DODAG: The sub-DODAG of a node is a DODAG rooted at that node
that is a subset of a main DODAG the node belongs to. It is
formed by the other nodes in the main DODAG whose paths to the
main DODAG root pass through that node.
2.3. Requirements Language 2.3. 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
14 [RFC2119][RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Extending RFC 6550 3. Extending RFC 6550
The DODAG Configuration Option is defined in Section 6.7.6 of The DODAG Configuration option is defined in Section 6.7.6 of
[RFC6550]. Its purpose is extended to distribute configuration [RFC6550]. Its purpose is extended to distribute configuration
information affecting the construction and maintenance of the DODAG, information affecting the construction and maintenance of the DODAG,
as well as operational parameters for RPL on the DODAG, through the as well as operational parameters for RPL on the DODAG, through the
DODAG. As shown in Figure 1, the Option was originally designed with DODAG. The DODAG Configuration option was originally designed with
4 bit positions reserved for future use as Flags. four bit positions reserved for future use as flags.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x04 |Opt Length = 14| | |T| |A| ... | | Type = 0x04 |Opt Length = 14| | |T| |A| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
<- Flags -> <- flags ->
Figure 1: DODAG Configuration Option (Partial View) Figure 1: DODAG Configuration Option (Partial View)
This specification defines a new flag "Enable RFC8138 Compression" This specification defines a new flag, "Enable Compression per RFC
(T). The "T" flag is set to turn-on the use of [RFC8138] within the 8138 (T)". The 'T' flag is set to turn on the use of [RFC8138]
DODAG. The "T" flag is encoded in position 2 of the reserved Flags within the DODAG. The 'T' flag is encoded in position 2 of the
in the DODAG Configuration Option (counting from bit 0 as the most reserved flags in the DODAG Configuration option (counting from bit 0
significant bit) and set to 0 in legacy implementations as specified as the most significant bit) and set to 0 in legacy implementations
respectively in Sections 20.14 and 6.7.6 of [RFC6550]. as specified in Sections 20.14 and 6.7.6 of [RFC6550], respectively.
Section 4.3 of [USEofRPLinfo] updates [RFC6550] to indicate that the Section 4.1.2 of [RFC9008] updates [RFC6550] to indicate that the
definition of the Flags applies to Mode of Operation (MOP) values definition of the flags applies to Mode of Operation (MOP) values
zero (0) to six (6) only. For a MOP value of 7, [RFC8138] MUST be zero (0) to six (6) only. For a MOP value of 7, [RFC8138] MUST be
used on Links where 6LoWPAN Header Compression [RFC6282] applies and used on links where 6LoWPAN Header Compression [RFC6282] applies and
MUST NOT be used otherwise. MUST NOT be used otherwise.
The RPL DODAG Configuration Option is typically placed in a DODAG The RPL DODAG Configuration option is typically placed in a DIO
Information Object (DIO) message. The DIO message propagates down message. The DIO message propagates down the DODAG to form and then
the DODAG to form and then maintain its structure. The DODAG maintain its structure. The DODAG Configuration option is copied
Configuration Option is copied unmodified from parents to children. unmodified from parents to children. [RFC6550] states that "Nodes
[RFC6550] states that "Nodes other than the DODAG Root MUST NOT other than the DODAG root MUST NOT modify this information when
modify this information when propagating the DODAG Configuration propagating the DODAG Configuration option." Therefore, a legacy
option". Therefore, a legacy parent propagates the "T" flag as set parent propagates the 'T' flag as set by the Root, and when the 'T'
by the Root, and when the "T" flag is set, it is transparently flag is set, it is transparently flooded to all the nodes in the
flooded to all the nodes in the DODAG. DODAG.
4. Updating RFC 8138 4. Updating RFC 8138
A node SHOULD generate packets in the compressed form using [RFC8138] A node SHOULD generate packets in compressed form using [RFC8138] if
if and only if the "T" flag is set. This behavior can be overridden and only if the 'T' flag is set. This behavior can be overridden by
by configuration or network management. Overriding may be needed configuration or network management. Overriding may be needed, e.g.,
e.g., to turn on the compression in a network where all nodes support to turn on compression in a network where all nodes support [RFC8138]
[RFC8138] but the Root does not support this specification and cannot but the Root does not support this specification and cannot set the
set the "T" flag, or to disable it locally in case of a problem. 'T' flag, or to disable it locally in case of a problem.
The decision to use [RFC8138] is made by the originator of the packet The decision to use [RFC8138] is made by the originator of the
depending on its capabilities and its knowledge of the state of the packet, depending on its capabilities and its knowledge of the state
"T" flag. A router encapsulating a packet is the originator of the of the 'T' flag. A router encapsulating a packet is the originator
resulting packet and is responsible for compressing the outer headers of the resulting packet and is responsible for compressing the outer
with [RFC8138], but it MUST leave the encapsulated packet as is. headers per [RFC8138], but it MUST NOT perform compression on the
encapsulated packet.
An external target [USEofRPLinfo] is not expected to support An external target [RFC9008] is not expected to support [RFC8138].
[RFC8138]. In most cases, packets to and from an external target are In most cases, packets to and from an external target are tunneled
tunneled back and forth between the border router (referred to as back and forth between the border router (referred to as a 6LoWPAN
6LR) that serves the external target and the Root, regardless of the Router (6LR)) that serves the external target and the Root,
MOP used in the RPL DODAG. The inner packet is typically not regardless of the MOP used in the RPL DODAG. The inner packet is
compressed with [RFC8138], so for outgoing packets, the border router typically not compressed per [RFC8138], so for outgoing packets, the
just needs to decapsulate the (compressed) outer header and forward border router just needs to decapsulate the (compressed) outer header
the (uncompressed) inner packet towards the external target. and forward the (uncompressed) inner packet towards the external
target.
A router MUST uncompress a packet that is to be forwarded to an A border router that forwards a packet to an external target MUST
external target. Otherwise, the router MUST forward the packet in uncompress the packet first. In all other cases, a router MUST
the form that the source used, either compressed or uncompressed. forward a packet in the form that the source used, either compressed
or uncompressed.
A RUL [UNAWARE-LEAVES] is both a leaf and an external target. A RUL A RUL [RFC9010] is both a leaf and an external target. A RUL does
does not participate in RPL and depends on the parent router to not participate in RPL and depends on the parent router to obtain
obtain connectivity. In the case of a RUL, forwarding towards an connectivity. In the case of a RUL, forwarding towards an external
external target actually means delivering the packet. target actually means delivering the packet.
5. Transition Scenarios 5. Transition Scenarios
A node that supports [RFC8138] but not this specification can only be A node that supports [RFC8138] but not this specification can only be
used in a homogeneous network. Enabling the [RFC8138] compression used in a homogeneous network. Enabling compression per [RFC8138]
without a turn-on signaling method requires a "flag day"; by which without a turn-on signaling method requires a flag day, by which time
time all nodes must be upgraded, and at which point the network can all nodes must be upgraded and at which point the network can be
be rebooted with the [RFC8138] compression turned on. rebooted with 6LoRH compression [RFC8138] turned on.
The intent for this specification is to perform a migration once and The intent of this specification is to perform a migration once and
for all without the need for a flag day. In particular it is not the for all, without the need for a flag day. In particular, the intent
intention to undo the setting of the "T" flag. Though it is possible is not to undo the setting of the 'T' flag. Though it is possible to
to roll back (see Section 5.3), the roll back operation SHOULD be roll back (see Section 5.3), the rollback operation SHOULD be
complete before the network operator adds nodes that do not support complete before the network operator adds nodes that do not support
[RFC8138]. [RFC8138].
5.1. Coexistence 5.1. Coexistence
A node that supports this specification can operate in a network with A node that supports this specification can operate in a network with
the [RFC8138] compression turned on or off with the "T" flag set 6LoRH compression [RFC8138] turned on or off with the 'T' flag set
accordingly and in a network in transition from off to on or on to accordingly and in a network in transition from off to on or on to
off (see Section 5.2). off (see Section 5.2).
A node that does not support [RFC8138] can interoperate with nodes A node that does not support [RFC8138] can interoperate with nodes
that do in a network with [RFC8138] compression turned off. If the that do in a network with 6LoRH compression [RFC8138] turned off. If
compression is turned on, all the RPL-Aware Nodes are expected to be compression is turned on, all the RANs are expected to be able to
able to handle compressed packets in the compressed form. A node handle packets in compressed form. A node that cannot do so may
that cannot do so may remain connected to the network as a RUL as remain connected to the network as a RUL as described in [RFC9010].
described in [UNAWARE-LEAVES].
5.2. Inconsistent State While Migrating 5.2. Inconsistent State While Migrating
When the "T" flag is turned on by the Root, the information slowly When the 'T' flag is turned on by the Root, the information slowly
percolates through the DODAG as the DIO gets propagated. Some nodes percolates through the DODAG as the DIO gets propagated. Some nodes
will see the flag and start sourcing packets in the compressed form will see the flag and start sourcing packets in compressed form,
while other nodes in the same RPL DODAG are still not aware of it. while other nodes in the same RPL DODAG will still not be aware of
In non-storing mode, the Root will start using [RFC8138] with a it. In Non-Storing mode, the Root will start using [RFC8138] with a
Source Routing Header 6LoRH (SRH-6LoRH) that routes all the way to Source Routing Header 6LoRH (SRH-6LoRH) that routes all the way to
the parent router or to the leaf. the parent router or to the leaf.
To ensure that a packet is forwarded across the RPL DODAG in the form To ensure that a packet is forwarded across the RPL DODAG in the form
in which it was generated, it is required that all the RPL nodes in which it was generated, it is required that all the RPL nodes
support [RFC8138] at the time of the switch. support [RFC8138] at the time of the switch.
Setting the "T" flag is ultimately the responsibility of the Network Setting the 'T' flag is ultimately the responsibility of the network
Administrator. The expectation is that the network management or administrator. The expectation is that the network management or
upgrading tools in place enable the Network Administrator to know upgrading tools in place enable the network administrator to know
when all the nodes that may join a DODAG were migrated. In the case when all the nodes that may join a DODAG were migrated. In the case
of a RPL instance with multiple Roots, all nodes that participate to of a RPL Instance with multiple Roots, all nodes that participate in
the RPL Instance may potentially join any DODAG. The network MUST be the RPL Instance may potentially join any DODAG. The network MUST be
operated with the "T" flag unset until all nodes in the RPL Instance operated with the 'T' flag unset until all nodes in the RPL Instance
are upgraded to support this specification. are upgraded to support this specification.
5.3. Rolling Back 5.3. Rolling Back
When turning [RFC8138] compression off in the network, the Network When turning 6LoRH compression [RFC8138] off in the network, the
Administrator MUST wait until all nodes have converged to the "T" network administrator MUST wait until each node has its 'T' flag
flag unset before allowing nodes that do not support the compression unset before allowing nodes that do not support compression in the
in the network. To that effect, whether the compression is active in network. Information regarding whether compression is active in a
a node SHOULD be exposed the node's management interface. node SHOULD be exposed in the node's management interface.
Nodes that do not support [RFC8138] SHOULD NOT be deployed in a Nodes that do not support [RFC8138] SHOULD NOT be deployed in a
network where the compression is turned on. If that is done, the network where compression is turned on. If that is done, the node
node can only operate as a RUL. can only operate as a RUL.
6. IANA Considerations 6. IANA Considerations
This specification updates the Registry that was created for This specification updates the "DODAG Configuration Option Flags for
[RFC6550] as the registry for "DODAG Configuration Option Flags" and MOP 0..6" registry [RFC9008] (formerly the "DODAG Configuration
updated as the registry for "DODAG Configuration Option Flags for MOP Option Flags" registry, which was created for [RFC6550]), by
0..6" by [USEofRPLinfo], by allocating one new Flag as follows: allocating one new flag as follows:
+---------------+---------------------------------+-----------+ +------------+-------------------------------------+-----------+
| Bit Number | Capability Description | Reference | | Bit Number | Capability Description | Reference |
+---------------+---------------------------------+-----------+ +------------+-------------------------------------+-----------+
| 2 (suggested) | Turn on RFC8138 Compression (T) | THIS RFC | | 2 | Enable Compression per RFC 8138 (T) | RFC 9035 |
+---------------+---------------------------------+-----------+ +------------+-------------------------------------+-----------+
Table 1: New DODAG Configuration Option Flag Table 1: New DODAG Configuration Option Flag
IANA is requested to add [this document] as a reference for MOP 7 in IANA has added this document as a reference for MOP 7 in the RPL
the RPL Mode of Operation registry. "Mode of Operation" registry.
7. Security Considerations 7. Security Considerations
It is worth noting that in RPL [RFC6550], every node in the LLN that It is worth noting that in RPL [RFC6550], every node in the LLN that
is RPL-aware and has access to the RPL domain can inject any RPL- is RPL aware and has access to the RPL domain can inject any RPL-
based attack in the network, more in [RFC7416]. This document based attack in the network; see [RFC7416] for details. This
applies typically to an existing deployment and does not change its document typically applies to an existing deployment and does not
security requirements and operations. It is assumed that the change its security requirements and operations. It is assumed that
security mechanisms as defined for RPL are followed. the security mechanisms as defined for RPL are followed.
Setting the "T" flag before all routers are upgraded may cause a loss
of packets. The new bit is protected as the rest of the
configuration so this is just one of the many attacks that can happen
if an attacker manages to inject a corrupted configuration.
Setting and unsetting the "T" flag may create inconsistencies in the
network but as long as all nodes are upgraded to [RFC8138] support
they will be able to forward both forms. The source is responsible
for selecting whether the packet is compressed or not, and all
routers must use the format that the source selected. So the result
of an inconsistency is merely that both forms will be present in the
network, at an additional cost of bandwidth for packets in the
uncompressed form.
An attacker may unset the "T" flag to force additional energy Setting the 'T' flag before all routers are upgraded may cause a loss
consumption of child or descendant nodes in its subDAG. Conversely of packets. The new bit benefits from the same protection as the
it may set the "T" flag, so that nodes located downstream would rest of the information in the DODAG Configuration option that
compress when that it is not desired, potentially resulting in the transports it. Touching the new bit is just one of the many attacks
loss of packets. In a tree structure, the attacker would be in that can happen if an attacker manages to inject a corrupted
position to drop the packets from and to the attacked nodes. So the configuration option in the network.
attacks above would be more complex and more visible than simply
dropping selected packets. The downstream node may have other
parents and see both settings, which could raise attention.
8. Acknowledgments Setting and unsetting the 'T' flag may create inconsistencies in the
network, but as long as all nodes are upgraded to provide support for
[RFC8138], they will be able to forward both forms. The source is
responsible for selecting whether the packet is compressed or not,
and all routers must use the format that the source selected. So,
the result of an inconsistency is merely that both forms will be
present in the network, at an additional cost of bandwidth for
packets in uncompressed form.
The authors wish to thank Murray Kucherawy, Meral Shirazipour, Barry An attacker may unset the 'T' flag to force additional energy
Leiba, Tirumaleswar Reddy, Nagendra Kumar Nainar, Stewart Bryant, consumption of child or descendant nodes in its sub-DODAG.
Carles Gomez, Eric Vyncke, Roman Danyliw, and especially Benjamin Conversely, it may set the 'T' flag so that nodes located downstream
Kaduk, Alvaro Retana, Dominique Barthel and Rahul Jadhav for their would compress packets even when compression is not desired,
in-depth reviews and constructive suggestions. potentially causing packet loss. In a tree structure, the attacker
would be in a position to drop the packets from and to the attacked
nodes. So, the attacks mentioned above would be more complex and
more visible than simply dropping selected packets. The downstream
node may have other parents and see the bit with both settings; such
a situation may be detected, and an alert may be triggered.
Also many thanks to Michael Richardson for being always helpful and 8. References
responsive when need comes.
9. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <https://www.rfc-editor.org/info/rfc7102>. 2014, <https://www.rfc-editor.org/info/rfc7102>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network "IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>. April 2017, <https://www.rfc-editor.org/info/rfc8138>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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>.
[UNAWARE-LEAVES] [RFC9010] Thubert, P., Ed. and M. Richardson, "Routing for RPL
Thubert, P. and M. Richardson, "Routing for RPL Leaves", (Routing Protocol for Low-Power and Lossy Networks)
Work in Progress, Internet-Draft, draft-ietf-roll-unaware- Leaves", RFC 9010, DOI 10.17487/RFC9010, April 2021,
leaves-27, 17 December 2020, <https://tools.ietf.org/html/ <https://www.rfc-editor.org/info/rfc9010>.
draft-ietf-roll-unaware-leaves-27>.
10. Informative References 8.2. Informative References
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553, Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012, DOI 10.17487/RFC6553, March 2012,
skipping to change at page 9, line 41 skipping to change at line 420
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
and M. Richardson, Ed., "A Security Threat Analysis for and M. Richardson, Ed., "A Security Threat Analysis for
the Routing Protocol for Low-Power and Lossy Networks the Routing Protocol for Low-Power and Lossy Networks
(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
<https://www.rfc-editor.org/info/rfc7416>. <https://www.rfc-editor.org/info/rfc7416>.
[USEofRPLinfo] [RFC9008] Robles, M.I., Richardson, M., and P. Thubert, "Using RPI
Robles, I., Richardson, M., and P. Thubert, "Using RPI Option Type, Routing Header for Source Routes, and IPv6-
Option Type, Routing Header for Source Routes and IPv6-in- in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008,
IPv6 encapsulation in the RPL Data Plane", Work in DOI 10.17487/RFC9008, April 2021,
Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-42, <https://www.rfc-editor.org/info/rfc9008>.
12 November 2020, <https://tools.ietf.org/html/draft-ietf-
roll-useofrplinfo-42>. Acknowledgments
The authors wish to thank Murray Kucherawy, Meral Shirazipour, Barry
Leiba, Tirumaleswar Reddy, Nagendra Kumar Nainar, Stewart Bryant,
Carles Gomez, √Čric Vyncke, Roman Danyliw, and especially Benjamin
Kaduk, Alvaro Retana, Dominique Barthel, and Rahul Jadhav for their
in-depth reviews and constructive suggestions.
Also, many thanks to Michael Richardson for always being helpful and
responsive when the need arises.
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc.
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
06254 MOUGINS - Sophia Antipolis 06254 MOUGINS - Sophia Antipolis
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Li Zhao Li Zhao
Cisco Systems, Inc Cisco Systems, Inc.
Xinsi Building Xinsi Building
No. 926 Yi Shan Rd No. 926 Yi Shan Rd
SHANGHAI Shanghai
200233 200233
China China
Email: liz3@cisco.com Email: liz3@cisco.com
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