draft-ietf-roll-capabilities-06.txt   draft-ietf-roll-capabilities-07.txt 
ROLL R. Jadhav, Ed. ROLL R. Jadhav, Ed.
Internet-Draft Huawei Internet-Draft
Intended status: Standards Track P. Thubert Intended status: Standards Track P. Thubert
Expires: December 5, 2020 Cisco Expires: March 21, 2021 Cisco
M. Richardson M. Richardson
Sandelman Software Works Sandelman Software Works
R. Sahoo R. Sahoo
Juniper Juniper
June 3, 2020 September 17, 2020
RPL Capabilities RPL Capabilities
draft-ietf-roll-capabilities-06 draft-ietf-roll-capabilities-07
Abstract Abstract
This draft enables the discovery, advertisement and query of This draft enables the discovery, advertisement and query of
capabilities for RPL nodes. capabilities for RPL nodes.
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.
skipping to change at page 1, line 36 skipping to change at page 1, line 36
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 December 5, 2020. This Internet-Draft will expire on March 21, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 13 skipping to change at page 3, line 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
RPL [RFC6550] specifies a proactive distance-vector based routing RPL [RFC6550] specifies a proactive distance-vector based routing
scheme. The protocol creates a DAG-like structure which operates scheme. The protocol creates a DAG-like structure which operates
with a given "Mode of Operation" (MOP) determining the minimal and with a given "Mode of Operation" (MOP) determining the minimal and
mandatory set of primitives to be supported by all the participating mandatory set of primitives to be supported by all the participating
nodes. nodes.
This document adds a notion of capabilities using which nodes in the This document adds a notion of capabilities, through which a node in
network could inform its peers about its additional capabilities. the network could inform its peers about its additional capabilities.
This document highlights the differences of capabilities from that of This document highlights the differences between capabilities and
Mode of operation and explains the necessity of it. Mode of Operation and explains the necessity for the former.
1.1. Requirements Language and Terminology 1.1. Requirements Language and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
MOP: Mode of Operation. Identifies the MOP of the RPL Instance as MOP: Mode of Operation. Identifies the MOP of the RPL Instance as
administratively provisioned at and distributed by the DODAG root. administratively provisioned at and distributed by the DODAG root.
MOPex: Extended MOP: As defined in [I-D.ietf-roll-mopex]. MOPex: Extended MOP: As defined in [I-D.ietf-roll-mopex].
Capabilities: Additional features or capabilities that are supported Capabilities: Additional features or capabilities that are supported
by the node. by the node.
Cap: Abbreviated term used for Capability. Cap: Abbreviated term used for Capability.
Caps: Abbreviated term used for Capabilities. Caps: Abbreviated term used for Capabilities.
DAO: DODAG Advertisement Object. An RPL message used to advertise DAO: DODAG Advertisement Object. A RPL (pronounced ripple) message
the target information in order to establish routing adjacencies. used to advertise the target information in order to establish
routing adjacencies.
DIO: DODAG Information Object. An RPL message initiated by the root DIO: DODAG Information Object. A RPL message initiated by the root
and is used to advertise the network configuration information. and is used to advertise the network configuration information.
Current parent: Parent 6LR node before switching to the new path. Current parent: Parent 6LR node before switching to the new path.
NPDAO: No-Path DAO. A DAO message which has target with lifetime 0. NPDAO: No-Path DAO. A DAO message that contains a Transit
Information Option with lifetime equal to 0.
Upstream path/direction: Path or direction from the node to the Root Upstream path/direction: Path or direction from the node to the Root
in a DAG. in a DAG.
Downstream path/direction: Path or direction to the node from the Downstream path/direction: Path or direction to the node from the
Root in a DAG. Root in a DAG.
This document uses terminology described in [RFC6550]. For the sake This document uses terminology described in [RFC6550]. For the sake
of readability all the known relevant terms are repeated in this of readability all the known relevant terms are repeated in this
section. section.
1.2. What are Capabilities? 1.2. What are Capabilities?
Currently RPL specification does not have a mechanism whereby a node Currently RPL specification does not have a mechanism whereby a node
can signal the set of features that are available on its end. Such a can signal the set of features that are available on its end. Such a
mechanism could help the root to advertise its capabilities and in mechanism could help the root to advertise its capabilities and in
response also determine some advanced information about the response also determine some advanced information about the
capabilities of the joining nodes. This document defines capabilities of the joining nodes. This document defines
Capabilities which could be supported by the nodes and handshaked as Capabilities which could be supported by the nodes and handshaked as
part of RPL signaling. Capabilities are embedded as an RPL Control part of RPL signaling. Capabilities are embedded as a RPL Control
Message Option as defined in Section 6.7 of [RFC6550]. Message Option as defined in Section 6.7 of [RFC6550].
2. Requirements for this document 2. Requirements for this document
Following are the requirements considered for this documents: Following are the requirements considered for this documents:
REQ1: Backwards compatibility. The new options and new fields in REQ1: Optional capabilities handshake. Capabilities are features,
the DIO message should be backward compatible i.e. if there
are nodes which support old MOPs they could still operate in
their own instances.
REQ2: Optional capabilities handshake. Capabilities are features,
possibly optional, which could be handshaked between the nodes possibly optional, which could be handshaked between the nodes
and the root within an RPL Instance. and the root within an RPL Instance.
REQ3: Capabilities handshake could be optionally added with existing REQ2: Capabilities handshake could be optionally added with existing
MOPs. Capabilities been optional in nature could be put to MOPs. Capabilities, being optional in nature, could be put to
use with existing MOPs. Capabilities and MOP-extension is use with existing MOPs. Capabilities and MOP-extension are
mutually independent i.e. a DIO can have a capabilities mutually independent i.e. a DIO can have a capabilities
option, MOP-extension option or both in the same message. option, MOP-extension option or both in the same message.
REQ4: Capabilities could be explicitly queried. REQ3: Capabilities could be explicitly queried.
2.1. How are Capabilities different from existing RPL primitives? 2.1. How are Capabilities different from existing RPL primitives?
The Mode of Operation (MOP) field in RPL mandates the operational The Mode of Operation (MOP) field in RPL mandates the operational
requirement for the nodes joining as routers. MOP and DIO requirement for the nodes joining as routers. MOP and DIO
Configuration Option is strictly controlled by the Root node in RPL. Configuration Option is strictly controlled by the Root node in RPL.
Intermediate 6LRs cannot modify these fields. Also, the MOP never Intermediate 6LRs cannot modify these fields. Also, the MOP never
changes for the lifetime of the RPL Instance. Changes in DIO changes for the lifetime of the RPL Instance. Changes in DIO
Configuration Option are possible but are rare. Capabilities, on the Configuration Option are possible but are rare. Capabilities, on the
other hand, might change more dynamically. other hand, might change more dynamically.
RPL DIO message also carries routing metrics and constraints as RPL DIO message also carries routing metrics and constraints as
specified in [RFC6551]. Metrics and constraints are used as part of specified in [RFC6551]. Metrics and constraints are used in addition
objective function which aids in node's rank calculation. A router to an objective function to determine a node's rank calculation. A
may use capabilities carried in DIO message as additional metrics/ router may use capabilities carried in DIO message as additional
constraints. However, capabilities have a larger scope and may be metrics/constraints. However, capabilities have a larger scope and
carried in other messages other than DIO and can flow in both the may be carried in messages other than DIO and can flow in either
directions (upstream and downstream). direction (upstream and downstream).
3. Capabilities 3. Capabilities
Handling of Capabilities MUST be supported if the network uses MOPex Handling of Capabilities MUST be supported if the network uses MOPex
[I-D.ietf-roll-mopex]. [I-D.ietf-roll-mopex].
Note that capabilities and MOPex are mutually exclusive and it is Note that capabilities and MOPex are mutually exclusive and it is
possible for an implementation to support either or both of the possible for an implementation to support either or both of the
options. options.
3.1. Capability Control Message Option 3.1. Capability Control Message Option
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 = TODO | Option Length | Capabilities TLVs | Type = TODO | Option Length | Capabilities TLVs
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Capabilities Option Figure 1: Capabilities Option
Multiple capabilities could be sent in the same message. The length Multiple capabilities can be sent in the same message. The length
field allows the message parser to skip the capability TLV parsing. field allows the message parser to skip the capability TLV parsing.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CapType | Len |J|I|C| Flags | ... | CapType | Len |J|I|C| Flags | ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Capabilities TLV Figure 2: Capabilities TLV
Every capability is identified by its type and it may have an Every capability is identified by its type and it may have an
optional Capability Info. Note that a given capability may or may optional Capability Info. Note that a given capability may or may
not be diseminated with additional information depending on the scope not be disseminated with additional information depending on the
of the capability indicated by the I bit. scope of the capability indicated by the I bit.
Len: 8-bit unsigned integer, representing the length in octets of the Len: 8-bit unsigned integer, representing the length in octets of the
TLV, not including the CapType, Length and Flags fields. TLV, not including the CapType, Length and Flags fields.
J = Join only as leaf if capability not understood. J = Join only as leaf if capability not understood.
I = Ignore the message if this capability is not understood. I = Ignore the message if this capability is not understood.
C = Flag indicating that the capability MUST be copied in the C = Flag indicating that the capability MUST be copied in the
downstream message. downstream message.
3.2. Capabilities Handshake 3.2. Capabilities Handshake
The root node could advertise the set of capabilities it supports in The root node can advertise the set of capabilities it supports in
the DIO message. A node could take advantage of the knowledge that the DIO message. A node can take advantage of the knowledge that the
the root supports a particular capability. Similarly a node could root supports a particular capability. Similarly a node can
advertise its capabilities in the DAO message using the capability advertise its capabilities in the DAO message using the capability
control message option defined in this document. Capabilities control message option defined in this document. Capabilities
advertised by non-root nodes are strictly a subset of the advertised by non-root nodes are strictly a subset of the
capabilities advertised by the root. capabilities advertised by the root.
In storing MOP, the DAO message from the 6LR could contain multiple In storing MOP, the DAO message from the 6LR can contain multiple
target options because of the DAO-Aggregation. The targets of the target options because of the DAO-Aggregation. The targets of the
capabilities option are indicated by one or more Target options that capabilities option are indicated by one or more Target options that
precede the Capabilities Option. This handling is similar to the precede the Capabilities Option. This handling is similar to the
Transit Information Option as supported in Section 6.7.8. of Transit Information Option as supported in Section 6.7.8. of
[RFC6550]. [RFC6550].
4. Querying Capabilities 4. Querying Capabilities
Nodes may be interested in knowing the capabilities of another node Nodes may be interested in knowing the capabilities of another node
before taking an action. For e.g., Consider before taking an action. For example, consider
[I-D.ietf-roll-dao-projection], the Root may want to know the [I-D.ietf-roll-dao-projection], in which the Root may want to know
capabilities of the nodes along a network segment before it initiates the capabilities of the nodes along a network segment before it
a projected DAO to install the routes along that segment. initiates a projected DAO to install the routes along that segment.
Caps can be carried in existing RPL Control messages as Control Caps can be carried in existing RPL Control messages as Control
Options, however Caps can also be queried explicitly. This section Options, however Caps can also be queried explicitly. This section
provides a way for a node to query capability set of another node. provides a way for a node to query the capability set of another
The capability query and subsequent response messages are directly node. The capability query and subsequent response messages are
addressed between the two peers. directly addressed between the two peers.
4.1. Capability Query (CAPQ) 4.1. Capability Query (CAPQ)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RPLInstanceID | Flags | reserved | CAPQSequence | | RPLInstanceID | Flags | reserved | CAPQSequence |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option(s)... | Option(s)...
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 3: CAPQ base object Figure 3: CAPQ base object
CAPQSequence: One byte, Sequence number sent by the CAPQ sender CAPQSequence: One byte, Sequence number sent by the CAPQ sender and
which is reflected back by the responder in the CAPS message. reflected back by the responder in the CAPS message.
Flags: One byte, set to zero by sender, ignored by receiver. Flags: One byte, set to zero by sender, ignored by receiver.
reserved: One byte, set to zero by sender, ignored by receiver. reserved: One byte, set to zero by sender, ignored by receiver.
CAPQ base object may be followed by one or more options. The The CAPQ base object may be followed by one or more options. The
Capability Type List Control Option Figure 4 is used to carry a set Capability Type List Control Option (see Figure 4) is used to carry a
of capability types to query about. set of capability types to query about.
If the sender does not send Figure 4 option, this would indicate that If the sender does not send a Capability Type List Control Option,
the node intends to query the capability type list Figure 4 supported this indicates that the node intends to query the Capability Type
by the target node. List supported by the target node.
4.1.1. Capability Type List Control Option 4.1.1. Capability Type List Control Option
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 = TODO | Option Length | CapType1 | CapType2 | | Type = TODO | Option Length | CapType1 | CapType2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CapType3 | ..... | CapType3 | .....
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 8, line 11 skipping to change at page 8, line 9
Figure 5: CAPS base object Figure 5: CAPS base object
Flags: One byte, set to zero by sender, ignored by receiver. Flags: One byte, set to zero by sender, ignored by receiver.
reserved: One byte, set to zero by sender, ignored by receiver. reserved: One byte, set to zero by sender, ignored by receiver.
CAPQSequence: One byte, Sequence number copied from CAPQSequence CAPQSequence: One byte, Sequence number copied from CAPQSequence
received in the CAPQ message. received in the CAPQ message.
CAPS message SHOULD contain the capability set Figure 1 queried by CAPS message SHOULD contain the capability set Figure 1 queried by
the CAPQ sender. If the target node does not support subset of the the CAPQ sender. If the target node does not support a subset of the
queried capabilities then the Figure 4 option with the unsupported queried capabilities then the Capability Type List with the
cap-types SHOULD be sent back indicating the queried capabilities unsupported cap-types SHOULD be sent back indicating the queried
not-supported by the target node. For an example, check Appendix A.3 capabilities not-supported by the target node. For an example, check
Appendix A.3
If the CAPQ message does not contain any Figure 4 option then the If the CAPQ message does not contain any Capability Type List option
receiver MUST respond with the cap types it supports using Figure 4. then the receiver MUST respond with the cap types it supports using a
Capability Type List Option (see Figure 4).
If the capability set cannot be transmitted in a single message (for If the capability set cannot be transmitted in a single message (for
e.g., because of MTU limitations) then multiple CAPS messages could e.g., because of MTU limitations) then multiple CAPS messages could
be used. All the CAPS message MUST use the same CAPQSequence number be used. All the CAPS messages MUST use the same CAPQSequence number
copied from the corresponding CAPQ message. copied from the corresponding CAPQ message.
4.2.1. Secure CAPS 4.2.1. Secure CAPS
A Secure CAPS message follows the format in [RFC6550] Figure 7, where A Secure CAPS message follows the format in [RFC6550] Figure 7, where
the base message format is the CAPS message shown in Figure 5. the base message format is the CAPS message shown in Figure 5.
5. Guidelines for defining new capabilities 5. Guidelines for defining new capabilities
This section provides guidelines/recommendations towards defining new This section provides guidelines/recommendations towards defining new
capabilities. Note that the capabilities might be carried as part of capabilities. Note that the capabilities might be carried as part of
the multicast messaging such as DIO and hence the set should be used the multicast messaging such as DIO and hence the set should be used
in restrictive manner as far as possible. sparingly, as much as possible.
5.1. Handling Capability flags 5.1. Handling Capability flags
A node MUST drop or discard the message with an unknown capability A node MUST drop or discard the message with an unknown capability
with 'D' flag set. The message MUST be discarded silently. with the 'D' flag set. The message MUST be discarded silently.
The 'J' (join) flag can be set in context to a capability either by a The 'J' (join) flag can be set in context to a capability either by a
6LR or the root. The 'J' flag indicates that if the capability is 6LR or the root. The 'J' flag indicates that if the capability is
not supported by a node then it can join the instance only as a 6LN not supported by a node then it can join the instance only as a 6LN
(or do not join as 6LR). (or do not join as 6LR).
The 'C' (copy) flag is set by the node indicating that the The 'C' (copy) flag is set by the node indicating that the
capabilities MUST be copied downstream by the node even if the node capabilities MUST be copied downstream by the node even if the node
does not understand the capability. does not understand the capability.
5.1.1. Rules to handle capabilities flag 5.1.1. Rules to handle capabilities flag
On receiving a capability it does not support, the node MUST check On receiving a capability it does not support, the node MUST check
the 'J' flag of the capability before joining the Instance. If the the 'J' flag of the capability before joining the Instance. If the
'J' flag is set then it can only join as a 6LN. 'J' flag is set then it can only join as a 6LN.
If the node is operating as 6LR and subsequently it receives a If the node is operating as 6LR and subsequently it receives a
capability from its preferred parent which it does not understand capability from its preferred parent which it does not understand
with 'J' flag set, then the node has to switch itself to 6LN mode. with 'J' flag set, then the node has to switch itself to 6LN mode.
During switching the node needs to inform its downstream peers of its During switching, the node needs to inform its downstream peers of
changed status by sending a DIO with infinite rank as mentioned in its changed status by sending a DIO with infinite rank as mentioned
RFC6550. Alternatively, a node may decide to switch to another in RFC6550. Alternatively, a node may decide to switch to another
parent with compatible and known capabilities. parent with compatible and known capabilities.
Capabilities are used to indicate a feature that is supported by the Capabilities are used to indicate a feature that is supported by the
node. Capabilities are not meant for configuration management for node. Capabilities are not meant for configuration management for
e.g., setting a threshold. e.g., setting a threshold.
6. Node Capabilities 6. Node Capabilities
6.1. Capability Indicators 6.1. Capability Indicators
Capability Indicators indicates the capabilities supported by the Capability Indicators indicate the capabilities supported by the node
node in the form of simple flags. Capabilities who do not have in the form of simple flags. Capabilities that do not need
additional information to be specified could make use of these flags additional information to be specified can make use of these flags to
to indicate their support. indicate their support.
6.1.1. Format of Capability Indicators 6.1.1. Format of Capability Indicators
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CapType=0x01 | Len |J|I|C| Flags |T|..Indicators.. | CapType=0x01 | Len |J|I|C| Flags |T|..Indicators..
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Capability Indicators TLV Figure 6: Capability Indicators TLV
Flags: LRs MUST set it to 0. I bit will always be set to 0. Flags: LRs MUST set it to 0. I bit will always be set to 0.
T flag (Bit 1): Indicates whether the node supports 6LoRH [RFC8138]. T flag (Bit 1): Indicates whether the node supports 6LoRH [RFC8138].
6.2. Routing Resource Capability 6.2. Routing Resource Capability
Storing mode of operation requires each intermediate router in the Storing Mode of Operation requires each intermediate router in the
LLN to maintain routing states' information in the routing table. LLN to maintain routing state information in the routing table. LLN
LLN routers typically operate with constraints on processing power, routers typically operate with constraints on processing power,
memory, and energy (battery power). Memory limits the number of memory, and energy (battery power). Memory limits the size of
routing states an LR and BR can maintain. When the routing table of routing state an LR and BR can maintain. When the routing table of
an LR or BR is full, it will either reject the new DAO messages an LR or BR is full, it will either reject the new DAO messages
received or will use some replacement policy to remove a routing received or will use some replacement policy to remove a routing
entry and add the new one. Rejection of DAO messages will lead to an entry and add the new one. Rejection of DAO messages will lead to an
increase in DAO message transmission that impacts the energy and increase in DAO message transmission that impacts the energy and
network convergence time. Routing state replacement leads to network convergence time. Routing state replacement leads to
downward path downtime. downward path downtime.
One possible way to solve problems due to routing table size One possible way to solve problems due to routing table size
constraint is to use this information to add neighbors to the DAO constraint is to use this information to add neighbors to the DAO
parent set. Routing resource capability can be used by LR and BR to parent set. Routing resource capability can be used by LR and BR to
skipping to change at page 13, line 27 skipping to change at page 13, line 27
[TODO] implications of malicious attack involving setting the [TODO] implications of malicious attack involving setting the
capability flags. capability flags.
10. References 10. References
10.1. Normative References 10.1. Normative References
[I-D.ietf-roll-mopex] [I-D.ietf-roll-mopex]
Jadhav, R., Thubert, P., and M. Richardson, "Mode of Jadhav, R., Thubert, P., and M. Richardson, "Mode of
Operation extension", draft-ietf-roll-mopex-00 (work in Operation extension", draft-ietf-roll-mopex-01 (work in
progress), April 2020. progress), June 2020.
[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>.
[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,
skipping to change at page 14, line 12 skipping to change at page 14, line 12
10.2. Informative References 10.2. Informative References
[I-D.ietf-lwig-nbr-mgmt-policy] [I-D.ietf-lwig-nbr-mgmt-policy]
Jadhav, R., Sahoo, R., Duquennoy, S., and J. Eriksson, Jadhav, R., Sahoo, R., Duquennoy, S., and J. Eriksson,
"Neighbor Management Policy for 6LoWPAN", draft-ietf-lwig- "Neighbor Management Policy for 6LoWPAN", draft-ietf-lwig-
nbr-mgmt-policy-03 (work in progress), February 2019. nbr-mgmt-policy-03 (work in progress), February 2019.
[I-D.ietf-roll-dao-projection] [I-D.ietf-roll-dao-projection]
Thubert, P., Jadhav, R., and M. Gillmore, "Root initiated Thubert, P., Jadhav, R., and M. Gillmore, "Root initiated
routing state in RPL", draft-ietf-roll-dao-projection-10 routing state in RPL", draft-ietf-roll-dao-projection-11
(work in progress), May 2020. (work in progress), September 2020.
[I-D.thubert-roll-turnon-rfc8138] [I-D.thubert-roll-turnon-rfc8138]
Thubert, P. and L. Zhao, "Configuration option for RFC Thubert, P. and L. Zhao, "Configuration option for RFC
8138", draft-thubert-roll-turnon-rfc8138-03 (work in 8138", draft-thubert-roll-turnon-rfc8138-03 (work in
progress), July 2019. progress), July 2019.
[RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N., [RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N.,
and D. Barthel, "Routing Metrics Used for Path Calculation and D. Barthel, "Routing Metrics Used for Path Calculation
in Low-Power and Lossy Networks", RFC 6551, in Low-Power and Lossy Networks", RFC 6551,
DOI 10.17487/RFC6551, March 2012, DOI 10.17487/RFC6551, March 2012,
skipping to change at page 16, line 8 skipping to change at page 16, line 8
Assume that Root queries for capabilities {Cap1, Cap2, Cap3, Cap4} Assume that Root queries for capabilities {Cap1, Cap2, Cap3, Cap4}
from the peer node. However the peer node does not support or does from the peer node. However the peer node does not support or does
not understand capability {cap1, cap4}. In this case the peer node not understand capability {cap1, cap4}. In this case the peer node
will respond back with value of Cap2 and Cap3 (which it understands) will respond back with value of Cap2 and Cap3 (which it understands)
and set the CapTypeList option with {Cap1, Cap4} type. and set the CapTypeList option with {Cap1, Cap4} type.
Authors' Addresses Authors' Addresses
Rahul Arvind Jadhav (editor) Rahul Arvind Jadhav (editor)
Huawei Marathahalli
Kundalahalli Village, Whitefield,
Bangalore, Karnataka 560037 Bangalore, Karnataka 560037
India India
Phone: +91-080-49160700
Email: rahul.ietf@gmail.com Email: rahul.ietf@gmail.com
Pascal Thubert Pascal Thubert
Cisco Systems, Inc Cisco Systems, Inc
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
MOUGINS - Sophia Antipolis 06254 MOUGINS - Sophia Antipolis 06254
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
 End of changes. 35 change blocks. 
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