draft-ietf-roll-mopex-00.txt   draft-ietf-roll-mopex-01.txt 
ROLL R. Jadhav, Ed. ROLL R. Jadhav, Ed.
Internet-Draft Huawei Tech Internet-Draft Huawei Tech
Intended status: Standards Track P. Thubert Intended status: Standards Track P. Thubert
Expires: October 17, 2020 Cisco Expires: December 7, 2020 Cisco
M. Richardson M. Richardson
Sandelman Software Works Sandelman Software Works
April 15, 2020 June 5, 2020
Mode of Operation extension Mode of Operation extension
draft-ietf-roll-mopex-00 draft-ietf-roll-mopex-01
Abstract Abstract
RPL allows different mode of operations which allows nodes to have a RPL allows different mode of operations which allows nodes to have a
consensus on the basic primitives that must be supported to join the consensus on the basic primitives that must be supported to join the
network. The MOP field in [RFC6550] is of 3 bits and is fast network. The MOP field in [RFC6550] is of 3 bits and is fast
depleting. This document extends the MOP for future use. depleting. This document extends the MOP for future use.
Status of This Memo Status of This Memo
skipping to change at page 1, line 36 skipping to change at page 1, line 36
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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.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language and Terminology . . . . . . . . . . 2 1.1. Requirements Language and Terminology . . . . . . . . . . 3
2. Requirements for this document . . . . . . . . . . . . . . . 3 2. Requirements for this document . . . . . . . . . . . . . . . 3
3. Extended MOP Control Message Option . . . . . . . . . . . . . 3 3. Extended MOP Control Message Option . . . . . . . . . . . . . 4
3.1. Handling MOPex . . . . . . . . . . . . . . . . . . . . . 4 3.1. Handling MOPex . . . . . . . . . . . . . . . . . . . . . 4
3.2. Use of values 0-6 in the MOPex option . . . . . . . . . . 4 3.2. Use of values 0-6 in the MOPex option . . . . . . . . . . 4
4. Implementation Considerations . . . . . . . . . . . . . . . . 4 4. Extending RPL Control Options . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 5. Implementation Considerations . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Mode of operation: MOPex . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.2. New options: MOPex and Capabilities . . . . . . . . . . . 5 7.1. Mode of operation: MOPex . . . . . . . . . . . . . . . . 6
6.3. New Registry for Extended-MOP-value . . . . . . . . . . . 5 7.2. New options: MOPex and Capabilities . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7.3. New Registry for Extended-MOP-value . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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.
MOP as per [RFC6550] is a 3-bit value carried in DIO messages and is MOP as per [RFC6550] is a 3-bit value carried in DIO messages and is
specific to the RPL Instance. The receipient of the DIO message can specific to the RPL Instance. The receipient of the DIO message can
join the specified network as a router only when it can support the join the specified network as a router only when it can support the
primitives as required by the mode of operation value. For example, primitives as required by the mode of operation value. For example,
in case of MOP=3 (Storing MOP with multicast support) the nodes can in case of MOP=3 (Storing MOP with multicast support) the nodes can
join the network as routers only when they can handle the DAO join the network as routers only when they can handle the DAO
advertisements from the peers and manage routing tables. The 3-bit advertisements from the peers and manage routing tables. The 3-bit
value is already exhausted and requires replenishment. This document value is already exhausted and requires replenishment. This document
introduces a mechanism to extend mode of operation values. introduces a mechanism to extend mode of operation values.
This document further extends the RPL Control Option syntax to handle
generic flags. The primary aim of these flags is to define the
behaviour of a node not supporting the given control type. If a node
does not support a given RPL Control Option, there are three
possibilities:
REQ1: Strip off the option
REQ2: Copy the option as-is
REQ3: Ignore the message containing this option
REQ4: Let the node join in only as a 6LN to this parent
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 mode of operation of the RPL MOP: Mode of Operation. Identifies the mode of operation of the RPL
Instance as administratively provisioned at and distributed by the Instance as administratively provisioned at and distributed by the
DODAG root. DODAG root.
skipping to change at page 4, line 30 skipping to change at page 4, line 44
continues to be true even in case of MOPex. continues to be true even in case of MOPex.
3.2. Use of values 0-6 in the MOPex option 3.2. Use of values 0-6 in the MOPex option
The MOPex option could also be allowed to re-use the values 0-6, The MOPex option could also be allowed to re-use the values 0-6,
which have been used for MOP so far. The use of current MOPs in which have been used for MOP so far. The use of current MOPs in
MOPex indicates that the MOP is supported with extended set of MOPex indicates that the MOP is supported with extended set of
semantics for e.g., the capability options semantics for e.g., the capability options
[I-D.ietf-roll-capabilities]. [I-D.ietf-roll-capabilities].
4. Implementation Considerations 4. Extending RPL Control Options
Section 6.7.1 of RFC6550 explains the RPL Control Message Option
Generic Format. This document extends this format to following:
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------
| |X| OptionType| Option Length |Opt Flags|J|I|C| Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------
Figure 2: Extended RPL Option Format
New fields in extended RPL Control Message Option Format:
'X' bit in Option Type: Value 1 indicates that this is an extended
option. If the 'X' flag is set, a 1 byte Option Flags follows the
Option Length field.
Option Length: 8-bit unsigned integer, representing the length in
octets of the option, not including the Option Type and Length
fields. Option Flags and variable length Option Data fields are
included in the length.
'J' (Join) bit in Option Flags: A node MUST join only as a 6LN if
the Option Type is not understood.
'C' (Copy) bit in Option Flags: A node which does not understand
the Option Type MUST copy the Option while generating the
corresponding message. For e.g., if a 6LR receives a DIO message
with an unknown Option with 'C' bit set and if the 6LR choses to
accept this node as the preferred parent then the node MUST copy
this option in the subsequent DIO message it generates.
Alternatively, if the 'C' flag is unset the node MUST strip off
the option and process the message.
'I' (Ignore) bit in Option Flags: A node which does not understand
the Option Type MUST ignore this whole message if the 'I' bit is
set. If 'I' bit is set than the value of 'J' and 'C' bits are
irrelevant and the message MUST be ignored.
Note that this format does not deprecate the previous format, it
simply extends it and the new format is applicable only when 2nd bit
('X' flag) of the Option Type is set. Option Type 0x40 to 0x7F are
thus applicable only as extended options.
+---------+---------+-----------------------------------------------+
| 'J' bit | 'C' bit | Handling |
+---------+---------+-----------------------------------------------+
| 0 | 0 | Strip off the option, and the node can join |
| | | as 6LR |
| 0 | 1 | Copy the option, and the node can join as 6LR |
| 1 | NA | Join as 6LN |
+---------+---------+-----------------------------------------------+
Table 1: Option Flags handling
If a node receives an unknown Option without 'X' flag set then the
node MUST ignore the option and process the message. The option MUST
be treated as if J=0, C=0, I=0.
5. Implementation Considerations
[RFC6550], it was possible to discard an unsupported DIO-MOP just by [RFC6550], it was possible to discard an unsupported DIO-MOP just by
inspecting the base message. With this document, the MOPex is a inspecting the base message. With this document, the MOPex is a
different control message option and thus the discarding of the DIO different control message option and thus the discarding of the DIO
message could happen after inspecting the message options. message could happen after inspecting the message options.
5. Acknowledgements 6. Acknowledgements
6. IANA Considerations Using 'I' bit was Pascal Thubert's idea.
6.1. Mode of operation: MOPex 7. IANA Considerations
7.1. Mode of operation: MOPex
IANA is requested to assign a new Mode of Operation, named "MOPex" IANA is requested to assign a new Mode of Operation, named "MOPex"
for MOP extension under the RPL registry. The value of 7 is to be for MOP extension under the RPL registry. The value of 7 is to be
assigned from the "Mode of Operation" space [RFC6550] assigned from the "Mode of Operation" space [RFC6550]
+-------+-------------+---------------+ +-------+-------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-------------+---------------+ +-------+-------------+---------------+
| 7 | MOPex | This document | | 7 | MOPex | This document |
+-------+-------------+---------------+ +-------+-------------+---------------+
Mode of Operation Mode of Operation
6.2. New options: MOPex and Capabilities 7.2. New options: MOPex and Capabilities
A new entry is required for supporting new option "MOPex" in the "RPL A new entry is required for supporting new option "MOPex" in the "RPL
Control Message Options" space [RFC6550]. Control Message Options" space [RFC6550].
+-------+---------+---------------+ +-------+---------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------+---------+---------------+ +-------+---------+---------------+
| TBD1 | MOPex | This document | | TBD1 | MOPex | This document |
+-------+---------+---------------+ +-------+---------+---------------+
New options New options
6.3. New Registry for Extended-MOP-value 7.3. New Registry for Extended-MOP-value
IANA is requested to create a registry for the extended-MOP-value IANA is requested to create a registry for the extended-MOP-value
(MOPex). This registry should be located in TODO. New MOPex values (MOPex). This registry should be located in TODO. New MOPex values
may be allocated only by an IETF review. Currently no values are may be allocated only by an IETF review. Currently no values are
defined by this document. Each value is tracked with the following defined by this document. Each value is tracked with the following
qualities: qualities:
o MOPex value o MOPex value
o Description o Description
o Defining RFC o Defining RFC
7. Security Considerations 8. Security Considerations
The options defined in this document are carried in the base message The options defined in this document are carried in the base message
objects as defined in [RFC6550]. The RPL control message options are objects as defined in [RFC6550]. The RPL control message options are
protected by the same security mechanisms that protect the base protected by the same security mechanisms that protect the base
messages. messages.
Capabilities flag can reveal that the node has been upgraded or is Capabilities flag can reveal that the node has been upgraded or is
running a old feature set. This document assumes that the base running a old feature set. This document assumes that the base
messages that carry these options are protected by RPL security messages that carry these options are protected by RPL security
mechanisms and thus are not visible to a malicious node. mechanisms and thus are not visible to a malicious node.
8. References 9. References
8.1. Normative References 9.1. 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>.
[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>.
8.2. Informative References 9.2. Informative References
[I-D.ietf-roll-capabilities] [I-D.ietf-roll-capabilities]
Jadhav, R., Thubert, P., Richardson, M., and R. Sahoo, Jadhav, R., Thubert, P., Richardson, M., and R. Sahoo,
"RPL Capabilities", draft-ietf-roll-capabilities-02 (work "RPL Capabilities", draft-ietf-roll-capabilities-06 (work
in progress), March 2020. in progress), June 2020.
Authors' Addresses Authors' Addresses
Rahul Arvind Jadhav (editor) Rahul Arvind Jadhav (editor)
Huawei Tech Huawei Tech
Kundalahalli Village, Whitefield, Kundalahalli Village, Whitefield,
Bangalore, Karnataka 560037 Bangalore, Karnataka 560037
India India
Phone: +91-080-49160700 Phone: +91-080-49160700
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