draft-ietf-roll-aodv-rpl-07.txt   draft-ietf-roll-aodv-rpl-08.txt 
ROLL S. Anamalamudi ROLL S. Anamalamudi
Internet-Draft SRM University-AP Internet-Draft SRM University-AP
Intended status: Standards Track M. Zhang Intended status: Standards Track M. Zhang
Expires: October 14, 2019 Huawei Technologies Expires: November 8, 2020 Huawei Technologies
C. Perkins C. Perkins
Futurewei Deep Blue Sky Networks
S.V.R.Anand S.V.R.Anand
Indian Institute of Science Indian Institute of Science
B. Liu B. Liu
Huawei Technologies Huawei Technologies
April 12, 2019 May 7, 2020
Asymmetric AODV-P2P-RPL in Low-Power and Lossy Networks (LLNs) AODV based RPL Extensions for Supporting Asymmetric P2P Links in Low-
draft-ietf-roll-aodv-rpl-07 Power and Lossy Networks
draft-ietf-roll-aodv-rpl-08
Abstract Abstract
Route discovery for symmetric and asymmetric Point-to-Point (P2P) Route discovery for symmetric and asymmetric Point-to-Point (P2P)
traffic flows is a desirable feature in Low power and Lossy Networks traffic flows is a desirable feature in Low power and Lossy Networks
(LLNs). For that purpose, this document specifies a reactive P2P (LLNs). For that purpose, this document specifies a reactive P2P
route discovery mechanism for both hop-by-hop routing and source route discovery mechanism for both hop-by-hop routing and source
routing: Ad Hoc On-demand Distance Vector Routing (AODV) based RPL routing: Ad Hoc On-demand Distance Vector Routing (AODV) based RPL
protocol. Paired Instances are used to construct directional paths, protocol (AODV-RPL). Paired Instances are used to construct
in case some of the links between source and target node are directional paths, in case some of the links between source and
asymmetric. target node are asymmetric.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 14, 2019. This Internet-Draft will expire on November 8, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of AODV-RPL . . . . . . . . . . . . . . . . . . . . 6 3. Overview of AODV-RPL . . . . . . . . . . . . . . . . . . . . 5
4. AODV-RPL DIO Options . . . . . . . . . . . . . . . . . . . . 7 4. AODV-RPL DIO Options . . . . . . . . . . . . . . . . . . . . 6
4.1. AODV-RPL DIO RREQ Option . . . . . . . . . . . . . . . . 7 4.1. AODV-RPL RREQ Option . . . . . . . . . . . . . . . . . . 6
4.2. AODV-RPL DIO RREP Option . . . . . . . . . . . . . . . . 9 4.2. AODV-RPL RREP Option . . . . . . . . . . . . . . . . . . 8
4.3. AODV-RPL DIO Target Option . . . . . . . . . . . . . . . 10 4.3. AODV-RPL Target Option . . . . . . . . . . . . . . . . . 10
5. Symmetric and Asymmetric Routes . . . . . . . . . . . . . . . 11 5. Symmetric and Asymmetric Routes . . . . . . . . . . . . . . . 11
6. AODV-RPL Operation . . . . . . . . . . . . . . . . . . . . . 13 6. AODV-RPL Operation . . . . . . . . . . . . . . . . . . . . . 13
6.1. Route Request Generation . . . . . . . . . . . . . . . . 13 6.1. Route Request Generation . . . . . . . . . . . . . . . . 13
6.2. Receiving and Forwarding RREQ messages . . . . . . . . . 14 6.2. Receiving and Forwarding RREQ messages . . . . . . . . . 14
6.2.1. General Processing . . . . . . . . . . . . . . . . . 14 6.2.1. General Processing . . . . . . . . . . . . . . . . . 14
6.2.2. Additional Processing for Multiple Targets . . . . . 15 6.2.2. Additional Processing for Multiple Targets . . . . . 15
6.3. Generating Route Reply (RREP) at TargNode . . . . . . . . 16 6.3. Generating Route Reply (RREP) at TargNode . . . . . . . . 16
6.3.1. RREP-DIO for Symmetric route . . . . . . . . . . . . 16 6.3.1. RREP-DIO for Symmetric route . . . . . . . . . . . . 16
6.3.2. RREP-DIO for Asymmetric Route . . . . . . . . . . . . 16 6.3.2. RREP-DIO for Asymmetric Route . . . . . . . . . . . . 16
6.3.3. RPLInstanceID Pairing . . . . . . . . . . . . . . . . 16 6.3.3. RPLInstanceID Pairing . . . . . . . . . . . . . . . . 17
6.4. Receiving and Forwarding Route Reply . . . . . . . . . . 17 6.4. Receiving and Forwarding Route Reply . . . . . . . . . . 17
7. Gratuitous RREP . . . . . . . . . . . . . . . . . . . . . . . 18 7. Gratuitous RREP . . . . . . . . . . . . . . . . . . . . . . . 19
8. Operation of Trickle Timer . . . . . . . . . . . . . . . . . 19 8. Operation of Trickle Timer . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9.1. New Mode of Operation: AODV-RPL . . . . . . . . . . . . . 19 9.1. New Mode of Operation: AODV-RPL . . . . . . . . . . . . . 20
9.2. AODV-RPL Options: RREQ, RREP, and Target . . . . . . . . 19 9.2. AODV-RPL Options: RREQ, RREP, and Target . . . . . . . . 20
10. Security Considerations . . . . . . . . . . . . . . . . . . . 20 10. Security Considerations . . . . . . . . . . . . . . . . . . . 20
11. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 21 11. Link State Determination . . . . . . . . . . . . . . . . . . 21
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 12.1. Normative References . . . . . . . . . . . . . . . . . . 21
13.1. Normative References . . . . . . . . . . . . . . . . . . 21 12.2. Informative References . . . . . . . . . . . . . . . . . 22
13.2. Informative References . . . . . . . . . . . . . . . . . 22
Appendix A. Example: ETX/RSSI Values to select S bit . . . . . . 23 Appendix A. Example: ETX/RSSI Values to select S bit . . . . . . 23
Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . 24 Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . 24
B.1. Changes from version 06 to version 07 . . . . . . . . . . 24 B.1. Changes from version 07 to version 08 . . . . . . . . . . 24
B.2. Changes from version 05 to version 06 . . . . . . . . . . 24 B.2. Changes from version 06 to version 07 . . . . . . . . . . 24
B.3. Changes from version 04 to version 05 . . . . . . . . . . 24 B.3. Changes from version 05 to version 06 . . . . . . . . . . 25
B.4. Changes from version 03 to version 04 . . . . . . . . . . 24 B.4. Changes from version 04 to version 05 . . . . . . . . . . 25
B.5. Changes from version 02 to version 03 . . . . . . . . . . 25 B.5. Changes from version 03 to version 04 . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 B.6. Changes from version 02 to version 03 . . . . . . . . . . 25
Appendix C. Contributors . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction 1. Introduction
RPL[RFC6550] (Routing Protocol for LLNs (Low-Power and Lossy RPL [RFC6550] (Routing Protocol for Low-Power and Lossy Networks) is
Networks)) is a IPv6 distance vector routing protocol designed to an IPv6 distance vector routing protocol designed to support multiple
support multiple traffic flows through a root-based Destination- traffic flows through a root-based Destination-Oriented Directed
Oriented Directed Acyclic Graph (DODAG). Typically, a router does Acyclic Graph (DODAG). Typically, a router does not have routing
not have routing information for most other routers. Consequently, information for most other routers. Consequently, for traffic
for traffic between routers within the DODAG (i.e., Point-to-Point between routers within the DODAG (i.e., Point-to-Point (P2P) traffic)
(P2P) traffic) data packets either have to traverse the root in non- data packets either have to traverse the root in non-storing mode, or
storing mode, or traverse a common ancestor in storing mode. Such traverse a common ancestor in storing mode. Such P2P traffic is
P2P traffic is thereby likely to traverse longer routes and may thereby likely to traverse longer routes and may suffer severe
suffer severe congestion near the DAG root (for more information see congestion near the DAG root (for more information see [RFC6997],
[RFC6997], [RFC6998]). [RFC6998]).
To discover better paths for P2P traffic flows in RPL, P2P-RPL
[RFC6997] specifies a temporary DODAG where the source acts as a
temporary root. The source initiates DIOs encapsulating the P2P
Route Discovery option (P2P-RDO) with an address vector for both hop-
by-hop mode (H=1) and source routing mode (H=0). Subsequently, each
intermediate router adds its IP address and multicasts the P2P mode
DIOs, until the message reaches the Target Node, which then sends the
"Discovery Reply" object. P2P-RPL is efficient for source routing,
but much less efficient for hop-by-hop routing due to the extra
address vector overhead. However, for symmetric links, when the P2P
mode DIO message is being multicast from the source hop-by-hop,
receiving nodes can infer a next hop towards the source. When the
Target Node subsequently replies to the source along the established
forward route, receiving nodes determine the next hop towards the
Target Node. For hop-by-hop routes (H=1) over symmetric links, this
would allow efficient use of routing tables for P2P-RDO messages
instead of the "Address Vector".
RPL and P2P-RPL both specify the use of a single DODAG in networks of
symmetric links, where the two directions of a link MUST both satisfy
the constraints of the objective function. This disallows the use of
asymmetric links which are qualified in one direction. But,
application-specific routing requirements as defined in IETF ROLL
Working Group [RFC5548], [RFC5673], [RFC5826] and [RFC5867] may be
satisfied by routing paths using bidirectional asymmetric links. For
this purpose, [I-D.thubert-roll-asymlink] described bidirectional
asymmetric links for RPL [RFC6550] with Paired DODAGs, for which the
DAG root (DODAGID) is common for two Instances. This can satisfy
application-specific routing requirements for bidirectional
asymmetric links in core RPL [RFC6550]. Using P2P-RPL twice with
Paired DODAGs, on the other hand, requires two roots: one for the
source and another for the target node due to temporary DODAG
formation. For networks composed of bidirectional asymmetric links
(see Section 5), AODV-RPL specifies P2P route discovery, utilizing
RPL with a new MoP. AODV-RPL makes use of two multicast messages to
discover possibly asymmetric routes. This provides higher route
diversity and can find suitable routes that might otherwise go
undetected by RPL. AODV-RPL eliminates the need for address vector
overhead in hop-by-hop mode. This significantly reduces the control
packet size, which is important for Constrained LLN networks. Both
discovered routes (upward and downward) meet the application specific
metrics and constraints that are defined in the Objective Function
for each Instance [RFC6552]. On the other hand, the point-to-point
nature of routes discovered by AODV-RPL can reduce interference near
the root nodes and also provide routes with fewer hops, likely
improving performance in the network.
The route discovery process in AODV-RPL is modeled on the analogous The route discovery process in AODV-RPL is modeled on the analogous
procedure specified in AODV [RFC3561]. The on-demand nature of AODV procedure specified in AODV [RFC3561]. The on-demand nature of AODV
route discovery is natural for the needs of peer-to-peer routing in route discovery is natural for the needs of peer-to-peer routing in
RPL-based LLNs. AODV terminology has been adapted for use with AODV- RPL-based LLNs. AODV terminology has been adapted for use with AODV-
RPL messages, namely RREQ for Route Request, and RREP for Route RPL messages, namely RREQ for Route Request, and RREP for Route
Reply. AODV-RPL currently omits some features compared to AODV -- in Reply. AODV-RPL currently omits some features compared to AODV -- in
particular, flagging Route Errors, blacklisting unidirectional links, particular, flagging Route Errors, blacklisting unidirectional links,
multihoming, and handling unnumbered interfaces. multihoming, and handling unnumbered interfaces.
AODV-RPL reuses and provides a natural extension to the core RPL
functionality to support routes with birectional asymmetric links.
It retains RPL's DODAG formation, RPL Instance and the associated
Objective Function, trickle timers, and support for storing and non-
storing modes. AODV adds basic messages RREQ and RREP as part of RPL
DIO (DODAG Information Object) control messages, and does not utilize
the DAO message of RPL. AODV-RPL specifies a new MOP running in a
seperate instance dedicating to discover P2P routes, which may differ
from the P2MP routes discoverable by native RPL. AODV-RPL can be
operated whether or not native RPL is running otherwise.
2. Terminology 2. 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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in BCP
[RFC2119], [RFC8174]. This document uses the following terms: 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
AODV AODV
Ad Hoc On-demand Distance Vector Routing[RFC3561]. Ad Hoc On-demand Distance Vector Routing[RFC3561].
AODV-RPL Instance AODV-RPL Instance
Either the RREQ-Instance or RREP-Instance Either the RREQ-Instance or RREP-Instance
Asymmetric Route Asymmetric Route
The route from the OrigNode to the TargNode can traverse different The route from the OrigNode to the TargNode can traverse different
nodes than the route from the TargNode to the OrigNode. An nodes than the route from the TargNode to the OrigNode. An
asymmetric route may result from the asymmetry of links, such that asymmetric route may result from the asymmetry of links, such that
only one direction of the series of links fulfills the constraints only one direction of the series of links satisfies the Objective
in route discovery. Function during route discovery.
Bi-directional Asymmetric Link Bi-directional Asymmetric Link
A link that can be used in both directions but with different link A link that can be used in both directions but with different link
characteristics. characteristics.
DIO DIO
DODAG Information Object DODAG Information Object
DODAG RREQ-Instance (or simply RREQ-Instance) DODAG RREQ-Instance (or simply RREQ-Instance)
RPL Instance built using the DIO with RREQ option; used for RPL Instance built using the DIO with RREQ option; used for
skipping to change at page 5, line 51 skipping to change at page 5, line 19
and TargNode. and TargNode.
P2P P2P
Point-to-Point -- in other words, not constrained a priori to Point-to-Point -- in other words, not constrained a priori to
traverse a common ancestor. traverse a common ancestor.
reactive routing reactive routing
Same as "on-demand" routing. Same as "on-demand" routing.
RREQ-DIO message RREQ-DIO message
An AODV-RPL MoP DIO message containing the RREQ option. The An AODV-RPL MOP DIO message containing the RREQ option. The
RPLInstanceID in RREQ-DIO is assigned locally by the OrigNode. RPLInstanceID in RREQ-DIO is assigned locally by the OrigNode.
RREP-DIO message RREP-DIO message
An AODV-RPL MoP DIO message containing the RREP option. The An AODV-RPL MOP DIO message containing the RREP option. The
RPLInstanceID in RREP-DIO is typically paired to the one in the RPLInstanceID in RREP-DIO is typically paired to the one in the
associated RREQ-DIO message. associated RREQ-DIO message.
Source routing Source routing
A mechanism by which the source supplies the complete route A mechanism by which the source supplies the complete route
towards the target node along with each data packet [RFC6550]. towards the target node along with each data packet [RFC6550].
Symmetric route Symmetric route
The upstream and downstream routes traverse the same routers. The upstream and downstream routes traverse the same routers.
skipping to change at page 6, line 36 skipping to change at page 6, line 5
ART option ART option
AODV-RPL Target option: a target option defined in this document. AODV-RPL Target option: a target option defined in this document.
3. Overview of AODV-RPL 3. Overview of AODV-RPL
With AODV-RPL, routes from OrigNode to TargNode within the LLN With AODV-RPL, routes from OrigNode to TargNode within the LLN
network are established "on-demand". In other words, the route network are established "on-demand". In other words, the route
discovery mechanism in AODV-RPL is invoked reactively when OrigNode discovery mechanism in AODV-RPL is invoked reactively when OrigNode
has data for delivery to the TargNode but existing routes do not has data for delivery to the TargNode but existing routes do not
satisfy the application's requirements. The routes discovered by satisfy the application's requirements. AODV-RPL is thus functional
AODV-RPL are not constrained to traverse a common ancestor. Unlike without requiring the use of RPL or any other routing protocol.
RPL [RFC6550] and P2P-RPL [RFC6997], AODV-RPL can enable asymmetric
communication paths in networks with bidirectional asymmetric links. The routes discovered by AODV-RPL are not constrained to traverse a
For this purpose, AODV-RPL enables discovery of two routes: namely, common ancestor. AODV-RPL can enable asymmetric communication paths
one from OrigNode to TargNode, and another from TargNode to OrigNode. in networks with bidirectional asymmetric links. For this purpose,
When possible, AODV-RPL also enables symmetric route discovery along AODV-RPL enables discovery of two routes: namely, one from OrigNode
Paired DODAGs (see Section 5). to TargNode, and another from TargNode to OrigNode. When possible,
AODV-RPL also enables symmetric route discovery along Paired DODAGs
(see Section 5).
In AODV-RPL, routes are discovered by first forming a temporary DAG In AODV-RPL, routes are discovered by first forming a temporary DAG
rooted at the OrigNode. Paired DODAGs (Instances) are constructed rooted at the OrigNode. Paired DODAGs (Instances) are constructed
according to the AODV-RPL Mode of Operation (MoP) during route according to the AODV-RPL Mode of Operation (MOP) during route
formation between the OrigNode and TargNode. The RREQ-Instance is formation between the OrigNode and TargNode. The RREQ-Instance is
formed by route control messages from OrigNode to TargNode whereas formed by route control messages from OrigNode to TargNode whereas
the RREP-Instance is formed by route control messages from TargNode the RREP-Instance is formed by route control messages from TargNode
to OrigNode. Intermediate routers join the Paired DODAGs based on to OrigNode. Intermediate routers join the Paired DODAGs based on
the rank as calculated from the DIO message. Henceforth in this the Rank as calculated from the DIO message. Henceforth in this
document, the RREQ-DIO message means the AODV-RPL mode DIO message document, the RREQ-DIO message means the AODV-RPL mode DIO message
from OrigNode to TargNode, containing the RREQ option (see from OrigNode to TargNode, containing the RREQ option (see
Section 4.1). Similarly, the RREP-DIO message means the AODV-RPL Section 4.1). Similarly, the RREP-DIO message means the AODV-RPL
mode DIO message from TargNode to OrigNode, containing the RREP mode DIO message from TargNode to OrigNode, containing the RREP
option (see Section 4.2). The route discovered in the RREQ-Instance option (see Section 4.2). The route discovered in the RREQ-Instance
is used for transmitting data from TargNode to OrigNode, and the is used for transmitting data from TargNode to OrigNode, and the
route discovered in RREP-Instance is used for transmitting data from route discovered in RREP-Instance is used for transmitting data from
OrigNode to TargNode. OrigNode to TargNode.
4. AODV-RPL DIO Options 4. AODV-RPL DIO Options
4.1. AODV-RPL DIO RREQ Option 4.1. AODV-RPL RREQ Option
OrigNode sets its IPv6 address in the DODAGID field of the RREQ-DIO OrigNode sets its IPv6 address in the DODAGID field of the RREQ-DIO
message. A RREQ-DIO message MUST carry exactly one RREQ option. message. A RREQ-DIO message MUST carry exactly one RREQ option,
otherwise it SHOULD be dropped.
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 | Option Length |S|H|X| Compr | L | MaxRank | | Option Type | Option Length |S|H|X| Compr | L | MaxRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Orig SeqNo | | | Orig SeqNo | |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
| | | |
| | | |
| Address Vector (Optional, Variable Length) | | Address Vector (Optional, Variable Length) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DIO RREQ option format for AODV-RPL MoP Figure 1: Format for AODV-RPL RREQ Option
OrigNode supplies the following information in the RREQ option: OrigNode supplies the following information in the RREQ option:
Type Option Type
The type assigned to the RREQ option (see Section 9.2). TBD2
Option Length Option Length
The length of the option in octets, excluding the Type and Length The length of the option in octets, excluding the Type and Length
fields. Variable due to the presence of the address vector and fields. Variable due to the presence of the address vector and
the number of octets elided according to the Compr value. the number of octets elided according to the Compr value.
S S
Symmetric bit indicating a symmetric route from the OrigNode to Symmetric bit indicating a symmetric route from the OrigNode to
the router transmitting this RREQ-DIO. the router transmitting this RREQ-DIO.
skipping to change at page 8, line 19 skipping to change at page 8, line 4
Reserved. Reserved.
Compr Compr
4-bit unsigned integer. Number of prefix octets that are elided 4-bit unsigned integer. Number of prefix octets that are elided
from the Address Vector. The octets elided are shared with the from the Address Vector. The octets elided are shared with the
IPv6 address in the DODAGID. This field is only used in source IPv6 address in the DODAGID. This field is only used in source
routing mode (H=0). In hop-by-hop mode (H=1), this field MUST be routing mode (H=0). In hop-by-hop mode (H=1), this field MUST be
set to zero and ignored upon reception. set to zero and ignored upon reception.
L L
2-bit unsigned integer determining the duration that a node is 2-bit unsigned integer determining the duration that a node is
able to belong to the temporary DAG in RREQ-Instance, including able to belong to the temporary DAG in RREQ-Instance, including
the OrigNode and the TargNode. Once the time is reached, a node the OrigNode and the TargNode. Once the time is reached, a node
MUST leave the DAG and stop sending or receiving any more DIOs for MUST leave the DAG and stop sending or receiving any more DIOs for
the temporary DODAG. The definition for the "L" bit is similar to the temporary DODAG.
that found in [RFC6997], except that the values are adjusted to
enable arbitrarily long route lifetime.
* 0x00: No time limit imposed. * 0x00: No time limit imposed.
* 0x01: 16 seconds * 0x01: 16 seconds
* 0x02: 64 seconds * 0x02: 64 seconds
* 0x03: 256 seconds * 0x03: 256 seconds
L is independent from the route lifetime, which is defined in the L is independent from the route lifetime, which is defined in the
DODAG configuration option. The route entries in hop-by-hop DODAG configuration option. The route entries in hop-by-hop
routing and states of source routing can still be maintained even routing and states of source routing can still be maintained even
after the DAG expires. after the node no longer maintains DAG connectivity or messaging.
MaxRank MaxRank
This field indicates the upper limit on the integer portion of the This field indicates the upper limit on the integer portion of the
rank (calculated using the DAGRank() macro defined in [RFC6550]). Rank (calculated using the DAGRank() macro defined in [RFC6550]).
A value of 0 in this field indicates the limit is infinity. A value of 0 in this field indicates the limit is infinity.
Orig SeqNo Orig SeqNo
Sequence Number of OrigNode, defined similarly as in AODV Sequence Number of OrigNode. See Section 6.1.
[RFC3561].
Address Vector Address Vector
A vector of IPv6 addresses representing the route that the RREQ- A vector of IPv6 addresses representing the route that the RREQ-
DIO has passed. It is only present when the 'H' bit is set to 0. DIO has passed. It is only present when the H bit is set to 0.
The prefix of each address is elided according to the Compr field. The prefix of each address is elided according to the Compr field.
A node MUST NOT join a RREQ instance if its own rank would equal to TargNode can join the RREQ instance at a Rank whose integer portion
or higher than MaxRank. Targnode can join the RREQ instance at a is equal to the MaxRank. Other nodes MUST NOT join a RREQ instance
rank whose integer portion is equal to the MaxRank. A router MUST if its own Rank would be equal to or higher than MaxRank. A router
discard a received RREQ if the integer part of the advertised rank MUST discard a received RREQ if the integer part of the advertised
equals or exceeds the MaxRank limit. This definition of MaxRank is Rank equals or exceeds the MaxRank limit.
the same as that found in [RFC6997].
4.2. AODV-RPL DIO RREP Option 4.2. AODV-RPL RREP Option
TargNode sets its IPv6 address in the DODAGID field of the RREP-DIO TargNode sets its IPv6 address in the DODAGID field of the RREP-DIO
message. A RREP-DIO message MUST carry exactly one RREP option. message. A RREP-DIO message MUST carry exactly one RREP option,
TargNode supplies the following information in the RREP option: otherwise the message SHOULD be dropped. TargNode supplies the
following information in the RREP 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 | Option Length |G|H|X| Compr | L | MaxRank | | Option Type | Option Length |G|H|X| Compr | L | MaxRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shift |Rsv| | | Shift |Rsv| |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
| | | |
| | | |
| Address Vector (Optional, Variable Length) | | Address Vector (Optional, Variable Length) |
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DIO RREP option format for AODV-RPL MoP Figure 2: Format for AODV-RPL RREP option
Type Option Type
The type assigned to the RREP option (see Section 9.2) TBD3
Option Length Option Length
The length of the option in octets, excluding the Type and Length The length of the option in octets, excluding the Type and Length
fields. Variable due to the presence of the address vector and fields. Variable due to the presence of the address vector and
the number of octets elided according to the Compr value. the number of octets elided according to the Compr value.
G G
Gratuitous route (see Section 7). Gratuitous route (see Section 7).
H H
Requests either source routing (H=0) or hop-by-hop (H=1) for the Requests either source routing (H=0) or hop-by-hop (H=1) for the
downstream route. It MUST be set to be the same as the 'H' bit in downstream route. It MUST be set to be the same as the H bit in
RREQ option. RREQ option.
X X
Reserved. Reserved.
Compr Compr
4-bit unsigned integer. Same definition as in RREQ option. 4-bit unsigned integer. Same definition as in RREQ option.
L L
2-bit unsigned integer defined as in RREQ option. 2-bit unsigned integer defined as in RREQ option.
MaxRank MaxRank
Similarly to MaxRank in the RREQ message, this field indicates the Similarly to MaxRank in the RREQ message, this field indicates the
upper limit on the integer portion of the rank. A value of 0 in upper limit on the integer portion of the Rank. A value of 0 in
this field indicates the limit is infinity. this field indicates the limit is infinity.
Shift Shift
6-bit unsigned integer. This field is used to recover the 6-bit unsigned integer. This field is used to recover the
original InstanceID (see Section 6.3.3); 0 indicates that the original RPLInstanceID (see Section 6.3.3); 0 indicates that the
original InstanceID is used. original RPLInstanceID is used.
Rsv Rsv
MUST be initialized to zero and ignored upon reception. MUST be initialized to zero and ignored upon reception.
Address Vector Address Vector
Only present when the 'H' bit is set to 0. For an asymmetric Only present when the H bit is set to 0. For an asymmetric route,
route, the Address Vector represents the IPv6 addresses of the the Address Vector represents the IPv6 addresses of the route that
route that the RREP-DIO has passed. For a symmetric route, it is the RREP-DIO has passed. For a symmetric route, it is the Address
the Address Vector when the RREQ-DIO arrives at the TargNode, Vector when the RREQ-DIO arrives at the TargNode, unchanged during
unchanged during the transmission to the OrigNode. the transmission to the OrigNode.
4.3. AODV-RPL DIO Target Option 4.3. AODV-RPL Target Option
The AODV-RPL Target (ART) Option is based on the Target Option in The AODV-RPL Target (ART) Option is based on the Target Option in
core RPL [RFC6550]. The Flags field is replaced by the Destination core RPL [RFC6550]. The Flags field is replaced by the Destination
Sequence Number of the TargNode and the Prefix Length field is Sequence Number of the TargNode and the Prefix Length field is
reduced to 7 bits so that the value is limited to be no greater than reduced to 7 bits so that the value is limited to be no greater than
127. 127.
A RREQ-DIO message MUST carry at least one ART Option. A RREP-DIO A RREQ-DIO message MUST carry at least one ART Option. A RREP-DIO
message MUST carry exactly one ART Option. message MUST carry exactly one ART Option. Otherwise, the message
SHOULD be dropped.
OrigNode can include multiple TargNode addresses via multiple AODV- OrigNode can include multiple TargNode addresses via multiple AODV-
RPL Target Options in the RREQ-DIO, for routes that share the same RPL Target Options in the RREQ-DIO, for routes that share the same
constraints. This reduces the cost to building only one DODAG. requirement on metrics. This reduces the cost to building only one
Furthermore, a single Target Option can be used for different DODAG.
TargNode addresses if they share the same prefix; in that case the
use of the destination sequence number is not defined in this
document.
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 | Option Length | Dest SeqNo |r|Prefix Length| | Option Type | Option Length | Dest SeqNo |r|Prefix Length|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ | + |
| Target Prefix / Address (Variable Length) | | Target Prefix / Address (Variable Length) |
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Target option format for AODV-RPL MoP Figure 3: Target option format for AODV-RPL MOP
Type Option Type
The type assigned to the ART Option TBD4
Option Length Option Length
Length of the option in octets excluding the Type and Length Length of the option in octets excluding the Type and Length
fields fields
Dest SeqNo Dest SeqNo
In RREQ-DIO, if nonzero, it is the last known Sequence Number for In RREQ-DIO, if nonzero, it is the last known Sequence Number for
TargNode for which a route is desired. In RREP-DIO, it is the TargNode for which a route is desired. In RREP-DIO, it is the
destination sequence number associated to the route. destination sequence number associated to the route.
skipping to change at page 11, line 44 skipping to change at page 11, line 27
by the sender and MUST be ignored by the receiver. by the sender and MUST be ignored by the receiver.
Prefix Length Prefix Length
7-bit unsigned integer. Number of valid leading bits in the IPv6 7-bit unsigned integer. Number of valid leading bits in the IPv6
Prefix. If Prefix Length is 0, then the value in the Target Prefix. If Prefix Length is 0, then the value in the Target
Prefix / Address field represents an IPv6 address, not a prefix. Prefix / Address field represents an IPv6 address, not a prefix.
Target Prefix / Address Target Prefix / Address
(variable-length field) An IPv6 destination address or prefix. (variable-length field) An IPv6 destination address or prefix.
The Prefix Length field contains the number of valid leading bits The Prefix Length field contains the number of valid leading bits
in the prefix. The bits in the Target Prefix / Address field in the prefix. The length of the field is the least number of
after the prefix length (if any) MUST be set to zero on octets that can contain all of the bits of the Prefix, in other
transmission and MUST be ignored on receipt. words Floor((7+(Prefix Length))/8) octets. The remaining bits in
the Target Prefix / Address field after the prefix length (if any)
MUST be set to zero on transmission and MUST be ignored on
receipt.
5. Symmetric and Asymmetric Routes 5. Symmetric and Asymmetric Routes
In Figure 4 and Figure 5, BR is the Border Router, O is the OrigNode, In Figure 4 and Figure 5, BR is the Border Router, O is the OrigNode,
R is an intermediate router, and T is the TargNode. If the RREQ-DIO R is an intermediate router, and T is the TargNode. If the RREQ-DIO
arrives over an interface that is known to be symmetric, and the 'S' arrives over an interface that is known to be symmetric, and the S
bit is set to 1, then it remains as 1, as illustrated in Figure 4. bit is set to 1, then it remains as 1, as illustrated in Figure 4.
If an intermediate router sends out RREQ-DIO with the 'S' bit set to If an intermediate router sends out RREQ-DIO with the S bit set to 1,
1, then all the one-hop links on the route from the OrigNode O to then all the one-hop links on the route from the OrigNode O to this
this router meet the requirements of route discovery, and the route router meet the requirements of route discovery, and the route can be
can be used symmetrically. used symmetrically.
BR BR
/----+----\ /----+----\
/ | \ / | \
/ | \ / | \
R R R R R R
_/ \ | / \ _/ \ | / \
/ \ | / \ / \ | / \
/ \ | / \ / \ | / \
R -------- R --- R ----- R -------- R R -------- R --- R ----- R -------- R
skipping to change at page 12, line 33 skipping to change at page 12, line 28
/ \ / \ / \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \ / \ / \
R ----- R ----------- R ----- R ----- R ----- R ---- R----- R R ----- R ----------- R ----- R ----- R ----- R ---- R----- R
>---- RREQ-Instance (Control: O-->T; Data: T-->O) -------> >---- RREQ-Instance (Control: O-->T; Data: T-->O) ------->
<---- RREP-Instance (Control: T-->O; Data: O-->T) -------< <---- RREP-Instance (Control: T-->O; Data: O-->T) -------<
Figure 4: AODV-RPL with Symmetric Paired Instances Figure 4: AODV-RPL with Symmetric Paired Instances
Upon receiving a RREQ-DIO with the 'S' bit set to 1, a node Upon receiving a RREQ-DIO with the S bit set to 1, a node determines
determines whether this one-hop link can be used symmetrically, i.e., whether this one-hop link can be used symmetrically, i.e., both the
both the two directions meet the requirements of data transmission. two directions meet the requirements of data transmission. If the
If the RREQ-DIO arrives over an interface that is not known to be RREQ-DIO arrives over an interface that is not known to be symmetric,
symmetric, or is known to be asymmetric, the 'S' bit is set to 0. If or is known to be asymmetric, the S bit is set to 0. If the S bit
the 'S' bit arrives already set to be '0', it is set to be '0' on arrives already set to be '0', it is set to be '0' on retransmission
retransmission (Figure 5). Therefore, for asymmetric route, there is (Figure 5). For an asymmetric route, there is at least one hop which
at least one hop which doesn't fulfill the constraints in the two doesn't satisfy the Objective Function. Based on the S bit received
directions. Based on the 'S' bit received in RREQ-DIO, the TargNode in RREQ-DIO, TargNode T determines whether or not the route is
T determines whether or not the route is symmetric before symmetric before transmitting the RREP-DIO message upstream towards
transmitting the RREP-DIO message upstream towards the OrigNode O. the OrigNode O.
The criteria used to determine whether or not each link is symmetric The criteria used to determine whether or not each link is symmetric
is beyond the scope of the document, and may be implementation- is beyond the scope of the document, and may be implementation-
specific. For instance, intermediate routers MAY use local specific. For instance, intermediate routers can use local
information (e.g., bit rate, bandwidth, number of cells used in information (e.g., bit rate, bandwidth, number of cells used in
6tisch), a priori knowledge (e.g. link quality according to previous 6tisch), a priori knowledge (e.g. link quality according to previous
communication) or use averaging techniques as appropriate to the communication) or use averaging techniques as appropriate to the
application. application.
Appendix A describes an example method using the ETX and RSSI to Appendix A describes an example method using the ETX and RSSI to
estimate whether the link is symmetric in terms of link quality is estimate whether the link is symmetric in terms of link quality is
given in using an averaging technique. given in using an averaging technique.
BR BR
skipping to change at page 13, line 39 skipping to change at page 13, line 35
<---- RREP-Instance (Control: T-->O; Data: O-->T) -------< <---- RREP-Instance (Control: T-->O; Data: O-->T) -------<
Figure 5: AODV-RPL with Asymmetric Paired Instances Figure 5: AODV-RPL with Asymmetric Paired Instances
6. AODV-RPL Operation 6. AODV-RPL Operation
6.1. Route Request Generation 6.1. Route Request Generation
The route discovery process is initiated when an application at the The route discovery process is initiated when an application at the
OrigNode has data to be transmitted to the TargNode, but does not OrigNode has data to be transmitted to the TargNode, but does not
have a route for the target that fulfills the requirements of the have a route that satisfies the Objective Function for the target of
data transmission. In this case, the OrigNode builds a local the data transmission. In this case, the OrigNode builds a local
RPLInstance and a DODAG rooted at itself. Then it transmits a DIO RPLInstance and a DODAG rooted at itself. Then it transmits a DIO
message containing exactly one RREQ option (see Section 4.1) via message containing exactly one RREQ option (see Section 4.1) via
link-local multicast. The DIO MUST contain at least one ART Option link-local multicast. The DIO MUST contain at least one ART Option
(see Section 4.3). The 'S' bit in RREQ-DIO sent out by the OrigNode (see Section 4.3). The S bit in RREQ-DIO sent out by the OrigNode is
is set to 1. set to 1.
Each node maintains a sequence number, which rolls over like a Each node maintains a sequence number; the operation is specified in
lollipop counter [Perlman83]; refer to section 7.2 of [RFC6550] for section 7.2 of [RFC6550]. When the OrigNode initiates a route
detailed operation. When the OrigNode initiates a route discovery discovery process, it MUST increase its own sequence number to avoid
process, it MUST increase its own sequence number to avoid conflicts conflicts with previously established routes. The sequence number is
with previously established routes. The sequence number is carried carried in the Orig SeqNo field of the RREQ option.
in the OrigSeqNo field of the RREQ option.
The address in the ART Option can be a unicast IPv6 address or a The address in the ART Option can be a unicast IPv6 address or a
prefix. The OrigNode can initiate the route discovery process for prefix. The OrigNode can initiate the route discovery process for
multiple targets simultaneously by including multiple ART Options, multiple targets simultaneously by including multiple ART Options,
and within a RREQ-DIO the requirements for the routes to different and within a RREQ-DIO the requirements for the routes to different
TargNodes MUST be the same. TargNodes MUST be the same.
OrigNode can maintain different RPLInstances to discover routes with OrigNode can maintain different RPLInstances to discover routes with
different requirements to the same targets. Using the InstanceID different requirements to the same targets. Using the InstanceID
pairing mechanism (see Section 6.3.3), route replies (RREP-DIOs) for pairing mechanism (see Section 6.3.3), route replies (RREP-DIOs) for
different RPLInstances can be distinguished. different RPLInstances can be distinguished.
The transmission of RREQ-DIO obeys the Trickle timer. If the The transmission of RREQ-DIO obeys the Trickle timer [RFC6206]. If
duration specified by the "L" bit has elapsed, the OrigNode MUST the duration specified by the L bit has elapsed, the OrigNode MUST
leave the DODAG and stop sending RREQ-DIOs in the related leave the DODAG and stop sending RREQ-DIOs in the related
RPLInstance. RPLInstance.
6.2. Receiving and Forwarding RREQ messages 6.2. Receiving and Forwarding RREQ messages
6.2.1. General Processing 6.2.1. General Processing
Upon receiving a RREQ-DIO, a router which does not belong to the Upon receiving a RREQ-DIO, a router goes through the steps below. If
RREQ-instance goes through the following steps: the router does not belong to the RREQ-Instance, then the maximum
useful rank (MaxUseRank) is MaxRank. Otherwise, MaxUseRank is set to
be the Rank value that was stored when the router processed the best
previous RREQ for the DODAG with the given RREQ-Instance.
Step 1: Step 1:
If the 'S' bit in the received RREQ-DIO is set to 1, the router If the S bit in the received RREQ-DIO is set to 1, the router MUST
MUST check the two directions of the link by which the RREQ-DIO is determine whether each direction of the link (by which the RREQ-
received. In case that the downward (i.e. towards the TargNode) DIO is received) satisfies the Objective Function. In case that
direction of the link can't fulfill the requirements, the link the downward (i.e. towards the TargNode) direction of the link
can't be used symmetrically, thus the 'S' bit of the RREQ-DIO to does not satisfy the Objective Function, the link can't be used
be sent out MUST be set as 0. If the 'S' bit in the received symmetrically, thus the S bit of the RREQ-DIO to be sent out MUST
RREQ-DIO is set to 0, the router only checks into the upward be set as 0. If the S bit in the received RREQ-DIO is set to 0,
direction (towards the OrigNode) of the link. the router MUST only check into the upward direction (towards the
OrigNode) of the link.
If the upward direction of the link can fulfill the requirements If the upward direction of the link can satisfy the Objective
indicated in the constraint option, and the router's rank would Function (defined in [RFC6551]), and the router's Rank would not
not exceed the MaxRank limit, the router joins the DODAG of the exceed the MaxUseRank limit, the router joins the DODAG of the
RREQ-Instance. The router that transmitted the received RREQ-DIO RREQ-Instance. The router that transmitted the received RREQ-DIO
is selected as the preferred parent. Later, other RREQ-DIO is selected as the preferred parent. Otherwise, if the Objective
messages might be received. How to maintain the parent set, Function is not satisfied or the MaxUseRank limit is exceeded, the
select the preferred parent, and update the router's rank obeys router MUST discard the received RREQ-DIO and MUST NOT join the
the core RPL and the OFs defined in ROLL WG. In case that the DODAG.
constraint or the MaxRank limit is not fulfilled, the router MUST
discard the received RREQ-DIO and MUST NOT join the DODAG.
Step 2: Step 2:
Then the router checks if one of its addresses is included in one Then the router checks if one of its addresses is included in one
of the ART Options. If so, this router is one of the TargNodes. of the ART Options. If so, this router is one of the TargNodes.
Otherwise, it is an intermediate router. Otherwise, it is an intermediate router.
Step 3: Step 3:
If the 'H' bit is set to 1, then the router (TargNode or If the H bit is set to 1, then the router (TargNode or
intermediate) MUST build the upward route entry accordingly. The intermediate) MUST build an upward route entry towards OrigNode
route entry MUST include at least the following items: Source which MUST include at least the following items: Source Address,
Address, InstanceID, Destination Address, Next Hop, Lifetime, and InstanceID, Destination Address, Next Hop, Lifetime, and Sequence
Sequence Number. The Destination Address and the InstanceID can Number. The Destination Address and the InstanceID respectively
be respectively learned from the DODAGID and the RPLInstanceID of can be learned from the DODAGID and the RPLInstanceID of the RREQ-
the RREQ-DIO, and the Source Address is copied from the ART DIO, and the Source Address is the address used by the local
Option. The next hop is the preferred parent. The lifetime is router to send data to the OrigNode. The Next Hop is the
set according to DODAG configuration and can be extended when the preferred parent. The lifetime is set according to DODAG
configuration (i.e., not the L bit) and can be extended when the
route is actually used. The sequence number represents the route is actually used. The sequence number represents the
freshness of the route entry, and it is copied from the Orig SeqNo freshness of the route entry, and it is copied from the Orig SeqNo
field of the RREQ option. A route entry with same source and field of the RREQ option. A route entry with the same source and
destination address, same InstanceID, but stale sequence number, destination address, same InstanceID, but stale sequence number,
SHOULD be deleted. MUST be deleted.
If the 'H' bit is set to 0, an intermediate router MUST include
the address of the interface receiving the RREQ-DIO into the
address vector.
Step 4: Step 4:
An intermediate router transmits a RREQ-DIO via link-local If the router is an intermediate router, then it transmits a RREQ-
multicast. TargNode prepares a RREP-DIO. DIO via link-local multicast; if the H bit is set to 0, the
intermediate router MUST include the address of the interface
receiving the RREQ-DIO into the address vector.. Otherwise, if
the router (i.e., TargNode) was not already associated with the
RREQ-Instance, it prepares a RREP-DIO Section 6.3. If, on the
other hand TargNode was already associated with the RREQ-Instance,
it takes no further action and does not send an RREP-DIO.
6.2.2. Additional Processing for Multiple Targets 6.2.2. Additional Processing for Multiple Targets
If the OrigNode tries to reach multiple TargNodes in a single RREQ- If the OrigNode tries to reach multiple TargNodes in a single RREQ-
instance, one of the TargNodes can be an intermediate router to the Instance, one of the TargNodes can be an intermediate router to the
others, therefore it SHOULD continue sending RREQ-DIO to reach other others, therefore it MUST continue sending RREQ-DIO to reach other
targets. In this case, before rebroadcasting the RREQ-DIO, a targets. In this case, before rebroadcasting the RREQ-DIO, a
TargNode MUST delete the Target Option encapsulating its own address, TargNode MUST delete the Target Option encapsulating its own address,
so that downstream routers with higher ranks do not try to create a so that downstream routers with higher Rank values do not try to
route to this TargetNode. create a route to this TargetNode.
An intermediate router could receive several RREQ-DIOs from routers An intermediate router could receive several RREQ-DIOs from routers
with lower ranks in the same RREQ-instance but have different lists with lower Rank values in the same RREQ-Instance but have different
of Target Options. When rebroadcasting the RREQ-DIO, the lists of Target Options. When rebroadcasting the RREQ-DIO, the
intersection of these lists SHOULD be included. For example, suppose intersection of these lists MUST be included. For example, suppose
two RREQ-DIOs are received with the same RPLInstance and OrigNode. two RREQ-DIOs are received with the same RPLInstance and OrigNode.
Suppose further that the first RREQ has (T1, T2) as the targets, and Suppose further that the first RREQ has (T1, T2) as the targets, and
the second one has (T2, T4) as targets. Then only T2 needs to be the second one has (T2, T4) as targets. Then only T2 needs to be
included in the generated RREQ-DIO. If the intersection is empty, it included in the generated RREQ-DIO. If the intersection is empty, it
means that all the targets have been reached, and the router SHOULD means that all the targets have been reached, and the router MUST NOT
NOT send out any RREQ-DIO. Any RREQ-DIO message with different ART send out any RREQ-DIO. For the purposes of determining the
Options coming from a router with higher rank is ignored. intersection with previous incoming RREQ-DIOs, the intermediate
router maintains a record of the targets that have been requested
associated with the RREQ-Instance. Any RREQ-DIO message with
different ART Options coming from a router with higher Rank is
ignored.
6.3. Generating Route Reply (RREP) at TargNode 6.3. Generating Route Reply (RREP) at TargNode
6.3.1. RREP-DIO for Symmetric route 6.3.1. RREP-DIO for Symmetric route
If a RREQ-DIO arrives at TargNode with the 'S' bit set to 1, there is If a RREQ-DIO arrives at TargNode with the S bit set to 1, there is a
a symmetric route along which both directions can fulfill the symmetric route along which both directions satisfy the Objective
requirements. Other RREQ-DIOs might later provide asymmetric upward Function. Other RREQ-DIOs might later provide asymmetric upward
routes (i.e. S=0). Selection between a qualified symmetric route routes (i.e. S=0). Selection between a qualified symmetric route
and an asymmetric route that might have better performance is and an asymmetric route that might have better performance is
implementation-specific and out of scope. If the implementation uses implementation-specific and out of scope. If the implementation
the symmetric route, the TargNode MAY delay transmitting the RREP-DIO selects the symmetric route, and the L bit is not 0, the TargNode MAY
for duration RREP_WAIT_TIME to await a better symmetric route. delay transmitting the RREP-DIO for duration RREP_WAIT_TIME to await
a symmetric route with a lower Rank. The value of RREP_WAIT_TIME is
set by default to 1/4 of the time duration determined by the L bit.
For a symmetric route, the RREP-DIO message is unicast to the next For a symmetric route, the RREP-DIO message is unicast to the next
hop according to the accumulated address vector (H=0) or the route hop according to the accumulated address vector (H=0) or the route
entry (H=1). Thus the DODAG in RREP-Instance does not need to be entry (H=1). Thus the DODAG in RREP-Instance does not need to be
built. The RPLInstanceID in the RREP-Instance is paired as defined built. The RPLInstanceID in the RREP-Instance is paired as defined
in Section 6.3.3. In case the 'H' bit is set to 0, the address in Section 6.3.3. In case the H bit is set to 0, the address vector
vector received in the RREQ-DIO MUST be included in the RREP-DIO. received in the RREQ-DIO MUST be included in the RREP-DIO. TargNode
TargNode increments its current sequence number and uses the increments its current sequence number and uses the incremented
incremented result in the Dest SeqNo in the ART option of the RREQ- result in the Dest SeqNo in the ART option of the RREQ-DIO. The
DIO. The address of the OrigNode MUST be encapsulated in the ART address of the OrigNode MUST be encapsulated in the ART Option and
Option and included in this RREP-DIO message. included in this RREP-DIO message.
6.3.2. RREP-DIO for Asymmetric Route 6.3.2. RREP-DIO for Asymmetric Route
When a RREQ-DIO arrives at a TargNode with the 'S' bit set to 0, the When a RREQ-DIO arrives at a TargNode with the S bit set to 0, the
TargNode MUST build a DODAG in the RREP-Instance rooted at itself in TargNode MUST build a DODAG in the RREP-Instance rooted at itself in
order to discover the downstream route from the OrigNode to the order to discover the downstream route from the OrigNode to the
TargNode. The RREP-DIO message MUST be re-transmitted via link-local TargNode. The RREP-DIO message MUST be re-transmitted via link-local
multicast until the OrigNode is reached or MaxRank is exceeded. multicast until the OrigNode is reached or MaxRank is exceeded. The
TargNode MAY delay transmitting the RREP-DIO for duration
RREP_WAIT_TIME to await a route with a lower Rank. The value of
RREP_WAIT_TIME is set by default to 1/4 of the time duration
determined by the L bit.
The settings of the fields in RREP option and ART option are the same The settings of the fields in RREP option and ART option are the same
as for the symmetric route, except for the 'S' bit. as for the symmetric route, except for the S bit.
6.3.3. RPLInstanceID Pairing 6.3.3. RPLInstanceID Pairing
Since the RPLInstanceID is assigned locally (i.e., there is no Since the RPLInstanceID is assigned locally (i.e., there is no
coordination between routers in the assignment of RPLInstanceID), the coordination between routers in the assignment of RPLInstanceID), the
tuple (OrigNode, TargNode, RPLInstanceID) is needed to uniquely tuple (OrigNode, TargNode, RPLInstanceID) is needed to uniquely
identify a discovered route. The upper layer applications may have identify a discovered route. It is possible that multiple route
different requirements and they can initiate the route discoveries discoveries with dissimilar Objective Functions are initiated
simultaneously. Thus between the same pair of OrigNode and TargNode, simultaneously. Thus between the same pair of OrigNode and TargNode,
there can be multiple AODV-RPL instances. To avoid any mismatch, the there can be multiple AODV-RPL route discovery instances. To avoid
RREQ-Instance and the RREP-Instance in the same route discovery MUST any mismatch, the RREQ-Instance and the RREP-Instance in the same
be paired somehow, e.g. using the RPLInstanceID. route discovery MUST be paired using the RPLInstanceID.
When preparing the RREP-DIO, a TargNode could find the RPLInstanceID When preparing the RREP-DIO, a TargNode could find the RPLInstanceID
to be used for the RREP-Instance is already occupied by another RPL to be used for the RREP-Instance is already occupied by another RPL
Instance from an earlier route discovery operation which is still Instance from an earlier route discovery operation which is still
active. In other words, it might happen that two distinct OrigNodes active. In other words, it might happen that two distinct OrigNodes
need routes to the same TargNode, and they happen to use the same need routes to the same TargNode, and they happen to use the same
RPLInstanceID for RREQ-Instance. In this case, the occupied RPLInstanceID for RREQ-Instance. In this case, the occupied
RPLInstanceID MUST NOT be used again. Then the second RPLInstanceID RPLInstanceID MUST NOT be used again. Then the second RPLInstanceID
MUST be shifted into another integer so that the two RREP-instances MUST be shifted into another integer so that the two RREP-instances
can be distinguished. In RREP option, the Shift field indicates the can be distinguished. In RREP option, the Shift field indicates the
shift to be applied to original RPLInstanceID. When the new shift to be applied to original RPLInstanceID. When the new
InstanceID after shifting exceeds 63, it rolls over starting at 0. InstanceID after shifting exceeds 63, it rolls over starting at 0.
For example, the original InstanceID is 60, and shifted by 6, the new For example, the original InstanceID is 60, and shifted by 6, the new
InstanceID will be 2. Related operations can be found in InstanceID will be 2. Related operations can be found in
Section 6.4. Section 6.4.
6.4. Receiving and Forwarding Route Reply 6.4. Receiving and Forwarding Route Reply
Upon receiving a RREP-DIO, a router which does not belong to the Upon receiving a RREP-DIO, a router which does not belong to the
RREQ-instance goes through the following steps: RREQ-Instance goes through the following steps:
Step 1: Step 1:
If the 'S' bit is set to 1, the router proceeds to step 2. If the S bit is set to 1, the router MUST proceed to step 2.
If the 'S' bit of the RREP-DIO is set to 0, the router MUST check If the S bit of the RREP-DIO is set to 0, the router MUST check
the downward direction of the link (towards the TargNode) over the downward direction of the link (towards the TargNode) over
which the RREP-DIO is received. If the downward direction of the which the RREP-DIO is received. If the downward direction of the
link can fulfill the requirements indicated in the constraint link can satisfy the Objective Function, and the router's Rank
option, and the router's rank would not exceed the MaxRank limit, would not exceed the MaxRank limit, the router joins the DODAG of
the router joins the DODAG of the RREP-Instance. The router that the RREP-Instance. The router that transmitted the received RREP-
transmitted the received RREP-DIO is selected as the preferred DIO is selected as the preferred parent. Afterwards, other RREP-
parent. Afterwards, other RREP-DIO messages can be received. How DIO messages can be received.
to maintain the parent set, select the preferred parent, and
update the router's rank obeys the core RPL and the OFs defined in
ROLL WG.
If the constraints are not fulfilled, the router MUST NOT join the If the Objective Function is not satisfied, the router MUST NOT
DODAG; the router MUST discard the RREQ-DIO, and does not execute join the DODAG; the router MUST discard the RREQ-DIO, and does not
the remaining steps in this section. execute the remaining steps in this section.
Step 2: Step 2:
The router next checks if one of its addresses is included in the The router next checks if one of its addresses is included in the
ART Option. If so, this router is the OrigNode of the route ART Option. If so, this router is the OrigNode of the route
discovery. Otherwise, it is an intermediate router. discovery. Otherwise, it is an intermediate router.
Step 3: Step 3:
If the 'H' bit is set to 1, then the router (OrigNode or If the H bit is set to 1, then the router (OrigNode or
intermediate) MUST build a downward route entry. The route entry intermediate) MUST build a downward route entry. The route entry
SHOULD include at least the following items: OrigNode Address, MUST include at least the following items: OrigNode Address,
InstanceID, TargNode Address as destination, Next Hop, Lifetime InstanceID, TargNode Address as destination, Next Hop, Lifetime
and Sequence Number. For a symmetric route, the next hop in the and Sequence Number. For a symmetric route, the Next Hop in the
route entry is the router from which the RREP-DIO is received. route entry is the router from which the RREP-DIO is received.
For an asymmetric route, the next hop is the preferred parent in For an asymmetric route, the Next Hop is the preferred parent in
the DODAG of RREQ-Instance. The InstanceID in the route entry the DODAG of RREQ-Instance. The InstanceID in the route entry
MUST be the original RPLInstanceID (after subtracting the Shift MUST be the original RPLInstanceID (after subtracting the Shift
field value). The source address is learned from the ART Option, field value). The source address is learned from the ART Option,
and the destination address is learned from the DODAGID. The and the destination address is learned from the DODAGID. The
lifetime is set according to DODAG configuration and can be lifetime is set according to DODAG configuration and can be
extended when the route is actually used. The sequence number extended when the route is actually used. The sequence number
represents the freshness of the route entry, and is copied from represents the freshness of the route entry, and is copied from
the Dest SeqNo field of the ART option of the RREP-DIO. A route the Dest SeqNo field of the ART option of the RREP-DIO. A route
entry with same source and destination address, same InstanceID, entry with same source and destination address, same InstanceID,
but stale sequence number, SHOULD be deleted. but stale sequence number, SHOULD be deleted.
If the 'H' bit is set to 0, for an asymmetric route, an If the H bit is set to 0, for an asymmetric route, an intermediate
intermediate router MUST include the address of the interface router MUST include the address of the interface receiving the
receiving the RREP-DIO into the address vector; for a symmetric RREP-DIO into the address vector; for a symmetric route, there is
route, there is nothing to do in this step. nothing to do in this step.
Step 4: Step 4:
If the receiver is the OrigNode, it can start transmitting the If the receiver is the OrigNode, it can start transmitting the
application data to TargNode along the path as provided in RREP- application data to TargNode along the path as provided in RREP-
Instance, and processing for the RREP-DIO is complete. Otherwise, Instance, and processing for the RREP-DIO is complete. Otherwise,
in case of an asymmetric route, the intermediate router transmits in case of an asymmetric route, the intermediate router transmits
the RREP-DIO via link-local multicast. In case of a symmetric the RREP-DIO via link-local multicast. In case of a symmetric
route, the RREP-DIO message is unicast to the next hop according route, the RREP-DIO message is unicast to the Next Hop according
to the address vector in the RREP-DIO (H=0) or the local route to the address vector in the RREP-DIO (H=0) or the local route
entry (H=1). The RPLInstanceID in the transmitted RREP-DIO is the entry (H=1). The RPLInstanceID in the transmitted RREP-DIO is the
same as the value in the received RREP-DIO. The local knowledge same as the value in the received RREP-DIO. The local knowledge
for the TargNode's sequence number SHOULD be updated. for the TargNode's sequence number SHOULD be updated.
Upon receiving a RREP-DIO, a router which already belongs to the
RREQ-Instance SHOULD drop the RREP-DIO.
7. Gratuitous RREP 7. Gratuitous RREP
In some cases, an Intermediate router that receives a RREQ-DIO In some cases, an Intermediate router that receives a RREQ-DIO
message MAY transmit a "Gratuitous" RREP-DIO message back to OrigNode message MAY transmit a "Gratuitous" RREP-DIO message back to OrigNode
instead of continuing to multicast the RREQ-DIO towards TargNode. instead of continuing to multicast the RREQ-DIO towards TargNode.
The intermediate router effectively builds the RREP-Instance on The intermediate router effectively builds the RREP-Instance on
behalf of the actual TargNode. The 'G' bit of the RREP option is behalf of the actual TargNode. The G bit of the RREP option is
provided to distinguish the Gratuitous RREP-DIO (G=1) sent by the provided to distinguish the Gratuitous RREP-DIO (G=1) sent by the
Intermediate node from the RREP-DIO sent by TargNode (G=0). Intermediate node from the RREP-DIO sent by TargNode (G=0).
The gratuitous RREP-DIO can be sent out when an intermediate router R The gratuitous RREP-DIO can be sent out when an intermediate router
receives a RREQ-DIO for a TargNode T, and R happens to have a more receives a RREQ-DIO for a TargNode, and the router has a more recent
recent (larger destination sequence number) pair of downward and (larger destination sequence number) pair of downward and upward
upward routes to T which also fulfill the requirements. routes to the TargNode which also satisfy the Objective Function.
In case of source routing, the intermediate router R MUST unicast the In case of source routing, the intermediate router MUST unicast the
received RREQ-DIO to TargNode T including the address vector between received RREQ-DIO to TargNode including the address vector between
the OrigNode O and the router R. Thus T can have a complete upward the OrigNode and the router. Thus the TargNode can have a complete
route address vector from itself to O. Then R MUST send out the upward route address vector from itself to the OrigNode. Then the
gratuitous RREP-DIO including the address vector from R to T. router MUST send out the gratuitous RREP-DIO including the address
vector from the router itself to the TargNode.
In case of hop-by-hop routing, R MUST unicast the received RREQ-DIO In case of hop-by-hop routing, the intermediate router MUST unicast
hop-by-hop to T. The routers along the route SHOULD build new route the received RREQ-DIO to the Next Hop on the route. The Next Hop
entries with the related RPLInstanceID and DODAGID in the downward router along the route MUST build new route entries with the related
direction. Then T MUST unicast the RREP-DIO hop-by-hop to R, and the RPLInstanceID and DODAGID in the downward direction. The above
routers along the route SHOULD build new route entries in the upward process will happen recursively until the RREQ-DIO arrives at the
direction. Upon receiving the unicast RREP-DIO, R sends the TargNode. Then the TargNode MUST unicast recursively the RREP-DIO
hop-by-hop to the intermediate router, and the routers along the
route SHOULD build new route entries in the upward direction. Upon
receiving the unicast RREP-DIO, the intermediate router sends the
gratuitous RREP-DIO to the OrigNode as defined in Section 6.3. gratuitous RREP-DIO to the OrigNode as defined in Section 6.3.
8. Operation of Trickle Timer 8. Operation of Trickle Timer
The trickle timer operation to control RREQ-Instance/RREP-Instance The trickle timer operation to control RREQ-Instance/RREP-Instance
multicast is similar to that in P2P-RPL [RFC6997]. multicast uses [RFC6206] to control RREQ-DIO and RREP-DIO
transmissions. The Trickle control of these DIO transmissions follow
the procedures described in the Section 8.3 of [RFC6550] entitled
"DIO Transmission".
9. IANA Considerations 9. IANA Considerations
9.1. New Mode of Operation: AODV-RPL 9.1. New Mode of Operation: AODV-RPL
IANA is required to assign a new Mode of Operation, named "AODV-RPL" IANA is asked to assign a new Mode of Operation, named "AODV-RPL" for
for Point-to-Point(P2P) hop-by-hop routing under the RPL registry. Point-to-Point(P2P) hop-by-hop routing from the "Mode of Operation"
The value of TBD1 is assigned from the "Mode of Operation" space Registry [RFC6550].
[RFC6550].
+-------------+---------------+---------------+ +-------------+---------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------------+---------------+---------------+ +-------------+---------------+---------------+
| TBD1 (5) | AODV-RPL | This document | | TBD1 (5) | AODV-RPL | This document |
+-------------+---------------+---------------+ +-------------+---------------+---------------+
Figure 6: Mode of Operation Figure 6: Mode of Operation
9.2. AODV-RPL Options: RREQ, RREP, and Target 9.2. AODV-RPL Options: RREQ, RREP, and Target
Three entries are required for new AODV-RPL options "RREQ", "RREP" IANA is asked to assign three new AODV-RPL options "RREQ", "RREP" and
and "ART" with values of TBD2 (0x0A), TBD3 (0x0B) and TBD4 (0x0C) "ART", as described in Figure 7 from the "RPL Control Message
from the "RPL Control Message Options" space [RFC6550]. Options" Registry [RFC6550].
+-------------+------------------------+---------------+ +-------------+------------------------+---------------+
| Value | Meaning | Reference | | Value | Meaning | Reference |
+-------------+------------------------+---------------+ +-------------+------------------------+---------------+
| TBD2 (0x0A) | RREQ Option | This document | | TBD2 (0x0A) | RREQ Option | This document |
+-------------+------------------------+---------------+ +-------------+------------------------+---------------+
| TBD3 (0x0B) | RREP Option | This document | | TBD3 (0x0B) | RREP Option | This document |
+-------------+------------------------+---------------+ +-------------+------------------------+---------------+
| TBD3 (0x0C) | ART Option | This document | | TBD4 (0x0C) | ART Option | This document |
+-------------+------------------------+---------------+ +-------------+------------------------+---------------+
Figure 7: AODV-RPL Options Figure 7: AODV-RPL Options
10. Security Considerations 10. Security Considerations
The security mechanisms defined in section 10 of [RFC6550] and In general, the security considerations for the operation of AODV-RPL
section 11 of [RFC6997] can also be applied to the control messages are similar to those for the operation of RPL (as described in
defined in this specification. The RREQ-DIO and RREP-DIO both have a Section 19 of the RPL specification [RFC6550]). Sections 6.1 and 10
secure variant, which provide integrity and replay protection as well of [RFC6550] describe RPL's security framework, which provides data
as optional confidentiality and delay protection. confidentiality, authentication, replay protection, and delay
protection services.
AODV-RPL can operate in the three security modes defined in
[RFC6550]. AODV-RPL messages SHOULD use a security mode at least as
strong as the security mode used in RPL.
o Unsecured. In this mode, RREQ-DIO and RREP-DIO are used without
any security fields as defined in section 6.1 of [RFC6550]. The
control messages can be protected by other security mechanisms,
e.g. link-layer security. This mode SHOULD NOT be used when RPL
is using Preinstalled mode or Authenticated mode (see below).
o Preinstalled. In this mode, AODV-RPL uses secure RREQ-DIO and
RREP-DIO messages, and a node wishing to join a secured network
will have been pre-configured with a shared key. A node can use
that key to join the AODV-RPL DODAG as a host or a router.
Unsecured messages MUST be dropped. This mode SHOULD NOT be used
when RPL is using Authenticated mode.
o Authenticated. In this mode, besides the preinstalled shared key, A router can join a temporary DAG created for a secure AODV-RPL route
a node MUST obtain a second key from a key authority. The discovery only if it can support the Security Configuration in use,
interaction between a node and the key authority is out of scope which also specifies the key in use. It does not matter whether the
for this specification. Authenticated mode may be useful, for key is preinstalled or dynamically acquired. The router must have
instance, to protect against a malicious rogue router advertising the key in use before it can join the DAG being created for a secure
false information in RREQ-DIO or RREP-DIO to include itself in the P2P-RPL route discovery.
discovered route. This mode would also prevent a malicious router
from initiating route discovery operations or launching denial-of-
service attacks to impair the performance of the LLN. AODV-RPL
can use the keys established with the Authenticated mode RPL
instance. Once a router or a host has been authenticated in the
RPL instance, it can join the AODV-RPL instance without any
further authentication. The authentication in AODV-RPL can also
be independent to RPL if, before joining the AODV-RPL instance,
the node obtains another key from the key authority.
11. Future Work If a rogue router knows the key for the Security Configuration in
use, it can join the secure AODV-RPL route discovery and cause
various types of damage. Such a rogue router could advertise false
information in its DIOs in order to include itself in the discovered
route(s). It could generate bogus RREQ-DIO, and RREP-DIO messages
carrying bad routes or maliciously modify genuine RREP-DIO messages
it receives. A rogue router acting as the OrigNode could launch
denial-of-service attacks against the LLN deployment by initiating
fake AODV-RPL route discoveries. In this type of scenario, RPL's
authenticated mode of operation, where a node can obtain the key to
use for a P2P-RPL route discovery only after proper authentication,
SHOULD be used.
There has been some discussion about how to determine the initial When RREQ-DIO message uses source routing option with 'H' set to 0,
state of a link after an AODV-RPL-based network has begun operation. some of the security concerns that led to the deprecation of Type 0
The current draft operates as if the links are symmetric until routing headers [RFC5095] may apply. To avoid the possibility of a
additional metric information is collected. The means for making RREP-DIO message traveling in a routing loop, if one of its addresses
link metric information is considered out of scope for AODV-RPL. In are present as part of the Source Route listed inside the message,
the future, RREQ and RREP messages could be equipped with new fields the Intermediate Router MUST NOT forward the message.
for use in verifying link metrics. In particular, it is possible to
identify unidirectional links; an RREQ received across a
unidirectional link has to be dropped, since the destination node
cannot make use of the received DODAG to route packets back to the
source node that originated the route discovery operation. This is
roughly the same as considering a unidirectional link to present an
infinite cost metric that automatically disqualifies it for use in
the reverse direction.
12. Contributors 11. Link State Determination
Abdur Rashid Sangi This document specifies that links are considered symmetric until
Huaiyin Institute of Technology additional information is collected. Other link metric information
No.89 North Beijing Road, Qinghe District can be acquired before AODV-RPL operation, by executing evaluation
Huaian 223001 procedures; for instance test traffic can be generated between nodes
P.R. China of the deployed network. During AODV-RPL operation, OAM techniques
Email: sangi_bahrian@yahoo.com for evaluating link state (see([RFC7548], [RFC7276], [co-ioam]) MAY
be used (at regular intervals appropriate for the LLN). The
evaluation procedures are out of scope for AODV-RPL.
13. References 12. References
13.1. Normative References 12.1. 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>.
[RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On-
Demand Distance Vector (AODV) Routing", RFC 3561,
DOI 10.17487/RFC3561, July 2003,
<https://www.rfc-editor.org/info/rfc3561>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095,
DOI 10.17487/RFC5095, December 2007,
<https://www.rfc-editor.org/info/rfc5095>.
[RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko,
"The Trickle Algorithm", RFC 6206, DOI 10.17487/RFC6206,
March 2011, <https://www.rfc-editor.org/info/rfc6206>.
[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>.
[RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing [RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N.,
Protocol for Low-Power and Lossy Networks (RPL)", and D. Barthel, "Routing Metrics Used for Path Calculation
RFC 6552, DOI 10.17487/RFC6552, March 2012, in Low-Power and Lossy Networks", RFC 6551,
<https://www.rfc-editor.org/info/rfc6552>. DOI 10.17487/RFC6551, March 2012,
<https://www.rfc-editor.org/info/rfc6551>.
[RFC6998] Goyal, M., Ed., Baccelli, E., Brandt, A., and J. Martocci,
"A Mechanism to Measure the Routing Metrics along a Point-
to-Point Route in a Low-Power and Lossy Network",
RFC 6998, DOI 10.17487/RFC6998, August 2013,
<https://www.rfc-editor.org/info/rfc6998>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
13.2. Informative References 12.2. Informative References
[I-D.thubert-roll-asymlink]
Thubert, P., "RPL adaptation for asymmetrical links",
draft-thubert-roll-asymlink-02 (work in progress),
December 2011.
[Perlman83]
Perlman, R., "Fault-Tolerant Broadcast of Routing
Information", December 1983.
[RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On-
Demand Distance Vector (AODV) Routing", RFC 3561,
DOI 10.17487/RFC3561, July 2003,
<https://www.rfc-editor.org/info/rfc3561>.
[RFC5548] Dohler, M., Ed., Watteyne, T., Ed., Winter, T., Ed., and
D. Barthel, Ed., "Routing Requirements for Urban Low-Power
and Lossy Networks", RFC 5548, DOI 10.17487/RFC5548, May
2009, <https://www.rfc-editor.org/info/rfc5548>.
[RFC5673] Pister, K., Ed., Thubert, P., Ed., Dwars, S., and T.
Phinney, "Industrial Routing Requirements in Low-Power and
Lossy Networks", RFC 5673, DOI 10.17487/RFC5673, October
2009, <https://www.rfc-editor.org/info/rfc5673>.
[RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation
Routing Requirements in Low-Power and Lossy Networks",
RFC 5826, DOI 10.17487/RFC5826, April 2010,
<https://www.rfc-editor.org/info/rfc5826>.
[RFC5867] Martocci, J., Ed., De Mil, P., Riou, N., and W. Vermeylen, [co-ioam] Ballamajalu, Rashmi., S.V.R., Anand., and Malati. Hegde,
"Building Automation Routing Requirements in Low-Power and "Co-iOAM: In-situ Telemetry Metadata Transport for
Lossy Networks", RFC 5867, DOI 10.17487/RFC5867, June Resource Constrained Networks within IETF Standards
2010, <https://www.rfc-editor.org/info/rfc5867>. Framework", 2018 10th International Conference on
Communication Systems & Networks (COMSNETS) pp.573-576,
Jan 2018.
[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
J. Martocci, "Reactive Discovery of Point-to-Point Routes J. Martocci, "Reactive Discovery of Point-to-Point Routes
in Low-Power and Lossy Networks", RFC 6997, in Low-Power and Lossy Networks", RFC 6997,
DOI 10.17487/RFC6997, August 2013, DOI 10.17487/RFC6997, August 2013,
<https://www.rfc-editor.org/info/rfc6997>. <https://www.rfc-editor.org/info/rfc6997>.
[RFC6998] Goyal, M., Ed., Baccelli, E., Brandt, A., and J. Martocci, [RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y.
"A Mechanism to Measure the Routing Metrics along a Point- Weingarten, "An Overview of Operations, Administration,
to-Point Route in a Low-Power and Lossy Network", and Maintenance (OAM) Tools", RFC 7276,
RFC 6998, DOI 10.17487/RFC6998, August 2013, DOI 10.17487/RFC7276, June 2014,
<https://www.rfc-editor.org/info/rfc6998>. <https://www.rfc-editor.org/info/rfc7276>.
[RFC7548] Ersue, M., Ed., Romascanu, D., Schoenwaelder, J., and A.
Sehgal, "Management of Networks with Constrained Devices:
Use Cases", RFC 7548, DOI 10.17487/RFC7548, May 2015,
<https://www.rfc-editor.org/info/rfc7548>.
Appendix A. Example: ETX/RSSI Values to select S bit Appendix A. Example: ETX/RSSI Values to select S bit
We have tested the combination of "RSSI(downstream)" and "ETX The combination of Received Signal Strength Indication(downstream)
(upstream)" to determine whether the link is symmetric or asymmetric (RSSI) and Expected Number of Transmissions(upstream)" (ETX) has been
at the intermediate nodes. The example of how the ETX and RSSI tested to determine whether a link is symmetric or asymmetric at
values are used in conjuction is explained below: intermediate nodes. ETX and RSSI values may be used in conjunction
as explained below:
Source---------->NodeA---------->NodeB------->Destination Source---------->NodeA---------->NodeB------->Destination
Figure 8: Communication link from Source to Destination Figure 8: Communication link from Source to Destination
+-------------------------+----------------------------------------+ +-------------------------+----------------------------------------+
| RSSI at NodeA for NodeB | Expected ETX at NodeA for NodeB->NodeA | | RSSI at NodeA for NodeB | Expected ETX at NodeA for NodeB->NodeA |
+-------------------------+----------------------------------------+ +-------------------------+----------------------------------------+
| > -60 | 150 | | > -60 | 150 |
| -70 to -60 | 192 | | -70 to -60 | 192 |
| -80 to -70 | 226 | | -80 to -70 | 226 |
| -90 to -80 | 662 | | -90 to -80 | 662 |
| -100 to -90 | 993 | | -100 to -90 | 993 |
+-------------------------+----------------------------------------+ +-------------------------+----------------------------------------+
Table 1: Selection of 'S' bit based on Expected ETX value Table 1: Selection of S bit based on Expected ETX value
We tested the operations in this specification by making the We tested the operations in this specification by making the
following experiment, using the above parameters. In our experiment, following experiment, using the above parameters. In our experiment,
a communication link is considered as symmetric if the ETX value of a communication link is considered as symmetric if the ETX value of
NodeA->NodeB and NodeB->NodeA (See Figure.8) are, say, within 1:3 NodeA->NodeB and NodeB->NodeA (see Figure 8) are within, say, a 1:3
ratio. This ratio should be taken as a notional metric for deciding ratio. This ratio should be understood as determining the link's
link symmetric/asymmetric nature, and precise definition of the ratio symmetric/asymmetric nature. NodeA can typically know the ETX value
is beyond the scope of the draft. In general, NodeA can only know in the direction of NodeA -> NodeB but it has no direct way of
the ETX value in the direction of NodeA -> NodeB but it has no direct knowing the value of ETX from NodeB->NodeA. Using physical testbed
way of knowing the value of ETX from NodeB->NodeA. Using physical experiments and realistic wireless channel propagation models, one
testbed experiments and realistic wireless channel propagation can determine a relationship between RSSI and ETX representable as an
models, one can determine a relationship between RSSI and ETX expression or a mapping table. Such a relationship in turn can be
representable as an expression or a mapping table. Such a used to estimate ETX value at nodeA for link NodeB--->NodeA from the
relationship in turn can be used to estimate ETX value at nodeA for received RSSI from NodeB. Whenever nodeA determines that the link
link NodeB--->NodeA from the received RSSI from NodeB. Whenever towards the nodeB is bi-directional asymmetric then the S bit is set
nodeA determines that the link towards the nodeB is bi-directional to 0. Later on, the link from NodeA to Destination is asymmetric
asymmetric then the "S" bit is set to "S=0". Later on, the link from with S bit remains set to 0.
NodeA to Destination is asymmetric with "S" bit remains to "0".
Appendix B. Changelog Appendix B. Changelog
B.1. Changes from version 06 to version 07 Note to the RFC Editor: please remove this section before
publication.
B.1. Changes from version 07 to version 08
o Instead of describing the need for routes to "fulfill the
requirements", specify that routes need to "satisfy the Objective
Function".
o Removed all normative dependencies on [RFC6997]
o Rewrote Section 10 to avoid duplication of language in cited
specifications.
o Added Section 11 with text and citations to more fully describe
how implementations determine whether links are symmetric.
o Modified text comparing AODV-RPL to other protocols to emphasize
the need for AODV-RPL instead of the problems with the other
protocols.
o Clarified that AODV-RPL uses some of the base RPL specification
but does not require an instance of RPL to run.
o Improved capitalization, quotation, and spelling variations.
o Specified behavior upon reception of a RREQ-DIO or RREP-DIO
message for an already existing DODAGID (e.g, Section 6.4).
o Fixed numerous language issues in IANA Considerations Section 9.
o For consistency, adjusted several mandates from SHOULD to MUST and
from SHOULD NOT to MUST NOT.
o Numerous editorial improvements and clarificaions.
B.2. Changes from version 06 to version 07
o Added definitions for all fields of the ART option (see o Added definitions for all fields of the ART option (see
Section 4.3). Modified definition of Prefix Length to prohibit Section 4.3). Modified definition of Prefix Length to prohibit
Prefix Length values greater than 127. Prefix Length values greater than 127.
o Modified the language from [RFC6550] Target Option definition so o Modified the language from [RFC6550] Target Option definition so
that the trailing zero bits of the Prefix Length are no longer that the trailing zero bits of the Prefix Length are no longer
described as "reserved". described as "reserved".
o Reclassified RFC 3561 and RFC 6998 as Informative. o Reclassified [RFC3561] and [RFC6998] as Informative.
o Added citation to RFC 8174 to Terminology section. o Added citation for [RFC8174] to Terminology section.
B.2. Changes from version 05 to version 06 B.3. Changes from version 05 to version 06
o Added Security Considerations based on the security mechanisms o Added Security Considerations based on the security mechanisms
defined in RFC 6550. defined in [RFC6550].
o Clarified the nature of improvements due to P2P route discovery o Clarified the nature of improvements due to P2P route discovery
versus bidirectional asymmetric route discovery. versus bidirectional asymmetric route discovery.
o Editorial improvements and corrections. o Editorial improvements and corrections.
B.3. Changes from version 04 to version 05 B.4. Changes from version 04 to version 05
o Add description for sequence number operations. o Add description for sequence number operations.
o Extend the residence duration L in section 4.1. o Extend the residence duration L in section 4.1.
o Change AODV-RPL Target option to ART option. o Change AODV-RPL Target option to ART option.
B.4. Changes from version 03 to version 04 B.5. Changes from version 03 to version 04
o Updated RREP option format. Remove the 'T' bit in RREP option. o Updated RREP option format. Remove the T bit in RREP option.
o Using the same RPLInstanceID for RREQ and RREP, no need to update o Using the same RPLInstanceID for RREQ and RREP, no need to update
[RFC6550]. [RFC6550].
o Explanation of Shift field in RREP. o Explanation of Shift field in RREP.
o Multiple target options handling during transmission. o Multiple target options handling during transmission.
B.5. Changes from version 02 to version 03 B.6. Changes from version 02 to version 03
o Include the support for source routing. o Include the support for source routing.
o Import some features from [RFC6997], e.g., choice between hop-by- o Import some features from [RFC6997], e.g., choice between hop-by-
hop and source routing, the "L" bit which determines the duration hop and source routing, the L bit which determines the duration of
of residence in the DAG, MaxRank, etc. residence in the DAG, MaxRank, etc.
o Define new target option for AODV-RPL, including the Destination o Define new target option for AODV-RPL, including the Destination
Sequence Number in it. Move the TargNode address in RREQ option Sequence Number in it. Move the TargNode address in RREQ option
and the OrigNode address in RREP option into ADOV-RPL Target and the OrigNode address in RREP option into ADOV-RPL Target
Option. Option.
o Support route discovery for multiple targets in one RREQ-DIO. o Support route discovery for multiple targets in one RREQ-DIO.
o New InstanceID pairing mechanism. o New InstanceID pairing mechanism.
Appendix C. Contributors
Abdur Rashid Sangi
Huaiyin Institute of Technology
No.89 North Beijing Road, Qinghe District
Huaian 223001
P.R. China
Email: sangi_bahrian@yahoo.com
Authors' Addresses Authors' Addresses
Satish Anamalamudi Satish Anamalamudi
SRM University-AP SRM University-AP
Amaravati Campus Amaravati Campus
Amaravati, Andhra Pradesh 522 502 Amaravati, Andhra Pradesh 522 502
India India
Email: satishnaidu80@gmail.com Email: satishnaidu80@gmail.com
Mingui Zhang Mingui Zhang
Huawei Technologies Huawei Technologies
No. 156 Beiqing Rd. Haidian District No. 156 Beiqing Rd. Haidian District
Beijing 100095 Beijing 100095
China China
Email: zhangmingui@huawei.com Email: zhangmingui@huawei.com
Charles E. Perkins Charles E. Perkins
Futurewei Deep Blue Sky Networks
2330 Central Expressway Saratoga 95070
Santa Clara 95050
United States United States
Email: charliep@computer.org Email: charliep@computer.org
S.V.R Anand S.V.R Anand
Indian Institute of Science Indian Institute of Science
Bangalore 560012 Bangalore 560012
India India
Email: anand@ece.iisc.ernet.in Email: anand@ece.iisc.ernet.in
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