draft-ietf-roll-p2p-measurement-10.txt   rfc6998.txt 
Internet Engineering Task Force M. Goyal, Ed. Internet Engineering Task Force (IETF) M. Goyal, Ed.
Internet-Draft University of Wisconsin Request for Comments: 6998 Univ. of Wisconsin Milwaukee
Intended status: Experimental Milwaukee Category: Experimental E. Baccelli
Expires: October 3, 2013 E. Baccelli ISSN: 2070-1721 INRIA
INRIA
A. Brandt A. Brandt
Sigma Designs Sigma Designs
J. Martocci J. Martocci
Johnson Controls Johnson Controls
April 1, 2013 August 2013
A Mechanism to Measure the Routing Metrics along a Point-to-point Route A Mechanism to Measure the Routing Metrics along a Point-to-Point Route
in a Low Power and Lossy Network in a Low-Power and Lossy Network
draft-ietf-roll-p2p-measurement-10
Abstract Abstract
This document specifies a mechanism that enables an RPL router to This document specifies a mechanism that enables a Routing Protocol
measure the aggregated values of given routing metrics along an for Low-power and Lossy Networks (RPL) router to measure the
existing route towards another RPL router, thereby allowing the aggregated values of given routing metrics along an existing route
router to decide if it wants to initiate the discovery of a better towards another RPL router, thereby allowing the router to decide if
route. it wants to initiate the discovery of a better route.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is not an Internet Standards Track specification; it is
Task Force (IETF). Note that other groups may also distribute published for examination, experimental implementation, and
working documents as Internet-Drafts. The list of current Internet- evaluation.
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document defines an Experimental Protocol for the Internet
and may be updated, replaced, or obsoleted by other documents at any community. This document is a product of the Internet Engineering
time. It is inappropriate to use Internet-Drafts as reference Task Force (IETF). It represents the consensus of the IETF
material or to cite them other than as "work in progress." community. It has received public review and has been approved for
publication by the Internet Engineering Steering Group (IESG). Not
all documents approved by the IESG are a candidate for any level of
Internet Standard; see Section 2 of RFC 5741.
This Internet-Draft will expire on October 3, 2013. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6998.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology ................................................5
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview ........................................................6
3. The Measurement Object (MO) . . . . . . . . . . . . . . . . . 6 3. The Measurement Object (MO) .....................................7
3.1. Format of the base MO . . . . . . . . . . . . . . . . . . 6 3.1. Format of the Base MO ......................................8
3.2. Secure MO . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2. Secure MO .................................................12
4. Originating a Measurement Request . . . . . . . . . . . . . . 11 4. Originating a Measurement Request ..............................13
4.1. When Measuring A Hop-by-hop Route with a Global 4.1. When Measuring a Hop-by-Hop Route with a Global
RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 12 RPLInstanceID .............................................14
4.2. When Measuring A Hop-by-hop Route with a Local 4.2. When Measuring a Hop-by-Hop Route with a Local
RPLInstanceID With Route Accumulation Off . . . . . . . . 13 RPLInstanceID with Route Accumulation Off .................15
4.3. When Measuring A Hop-by-hop Route with a Local 4.3. When Measuring a Hop-by-Hop Route with a Local
RPLInstanceID With Route Accumulation On . . . . . . . . . 14 RPLInstanceID with Route Accumulation On ..................16
4.4. When Measuring A Source Route . . . . . . . . . . . . . . 16 4.4. When Measuring a Source Route .............................17
5. Processing a Measurement Request at an Intermediate Point . . 17 5. Processing a Measurement Request at an Intermediate Point ......19
5.1. When Measuring A Hop-by-hop Route with a Global 5.1. When Measuring a Hop-by-Hop Route with a Global
RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 18 RPLInstanceID .............................................19
5.2. When Measuring A Hop-by-hop Route with a Local 5.2. When Measuring a Hop-by-Hop Route with a Local
RPLInstanceID With Route Accumulation Off . . . . . . . . 19 RPLInstanceID with Route Accumulation Off .................21
5.3. When Measuring A Hop-by-hop Route with a Local 5.3. When Measuring a Hop-by-Hop Route with a Local
RPLInstanceID With Route Accumulation On . . . . . . . . . 20 RPLInstanceID with Route Accumulation On ..................21
5.4. When Measuring A Source Route . . . . . . . . . . . . . . 21 5.4. When Measuring a Source Route .............................22
5.5. Final Processing . . . . . . . . . . . . . . . . . . . . . 21 5.5. Final Processing ..........................................23
6. Processing a Measurement Request at the End Point . . . . . . 22 6. Processing a Measurement Request at the End Point ..............23
6.1. Generating the Measurement Reply . . . . . . . . . . . . . 23 6.1. Generating the Measurement Reply ..........................24
7. Processing a Measurement Reply at the Start Point . . . . . . 23 7. Processing a Measurement Reply at the Start Point ..............25
8. Security Considerations . . . . . . . . . . . . . . . . . . . 24 8. Security Considerations ........................................25
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 9. IANA Considerations ............................................27
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 10. Acknowledgements ..............................................27
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 11. References ....................................................28
11.1. Normative References . . . . . . . . . . . . . . . . . . . 26 11.1. Normative References .....................................28
11.2. Informative References . . . . . . . . . . . . . . . . . . 27 11.2. Informative References ...................................28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction 1. Introduction
Point to point (P2P) communication between arbitrary routers in a Low Point-to-point (P2P) communication between arbitrary routers in a
power and Lossy Network (LLN) is a key requirement for many Low-power and Lossy Network (LLN) is a key requirement for many home
applications [RFC5826][RFC5867]. The IPv6 Routing Protocol for LLNs and commercial building automation applications [RFC5826] [RFC5867].
(RPL) [RFC6550] constrains the LLN topology to a Directed Acyclic The IPv6 Routing Protocol for LLNs (RPL) [RFC6550] constrains the LLN
Graph (DAG) built to optimize the routing costs to reach the DAG's topology to a Directed Acyclic Graph (DAG) built to optimize the
root. The P2P routing functionality, available under RPL, has the routing costs to reach the DAG's root. The P2P routing
following key limitations: functionality, available under RPL, has the following key
limitations:
o The P2P routes are restricted to use the DAG links only. Such P2P o The P2P routes are restricted to use the DAG links only. Such P2P
routes may potentially be suboptimal and may lead to traffic routes may potentially be suboptimal and may lead to traffic
congestion near the DAG root. congestion near the DAG root.
o RPL is a proactive routing protocol and hence requires all P2P o RPL is a proactive routing protocol and hence requires that all
routes to be established ahead of the time they are used. Many P2P routes be established ahead of the time they are used. Many
LLN applications require the ability to establish P2P routes "on LLN applications require the ability to establish P2P routes "on
demand". demand".
To ameliorate situations where the core RPL's P2P routing To ameliorate situations where the core RPL's P2P routing
functionality does not meet the application requirements functionality does not meet an application's requirements, [RFC6997]
[I-D.ietf-roll-p2p-rpl] describes P2P-RPL, an extension to core RPL. describes P2P-RPL, an extension to core RPL. P2P-RPL provides a
P2P-RPL provides a reactive mechanism to discover P2P routes that reactive mechanism to discover P2P routes that meet the specified
meet the specified routing constraints [RFC6551]. In some cases, the routing constraints [RFC6551]. In some cases, the application's
application requirements or the LLN's topological features allow a requirements or the LLN's topological features allow a router to
router to infer these routing constraints implicitly. For example, infer these routing constraints implicitly. For example, the
the application may require the end-to-end loss rate and/or latency application may require that the end-to-end loss rate and/or latency
along the route to be below certain thresholds or the LLN topology along the route be below certain thresholds, or the LLN topology may
may be such that a router can safely assume its destination to be be such that a router can safely assume that its destination is less
less than a certain number of hops away from itself. than a certain number of hops away from itself.
When the existing routes are deemed unsatisfactory but the router When the existing routes are deemed unsatisfactory but the router
does not implicitly know the routing constraints to be used in P2P- does not implicitly know the routing constraints to be used in
RPL route discovery, it may be necessary for the router to measure P2P-RPL route discovery, it may be necessary for the router to
the aggregated values of the routing metrics along the existing measure the aggregated values of the routing metrics along the
route. This knowledge will allow the router to frame reasonable existing route. This knowledge will allow the router to frame
routing constraints to discover a better route using P2P-RPL. For reasonable routing constraints to discover a better route using
example, if the router determines the aggregate ETX (Expected Number P2P-RPL. For example, if the router determines the aggregate ETX
of Transmissions) [RFC6551] along an existing route to be "x", it can (expected transmission count) [RFC6551] along an existing route to be
use "ETX < x*y", where y is a certain fraction, as the routing "x", it can use "ETX < x*y", where y is a certain fraction, as the
constraint for use in P2P-RPL route discovery. Note that it is routing constraint for use in P2P-RPL route discovery. Note that it
important that the routing constraints not be overly strict; is important that the routing constraints not be overly strict;
otherwise, the P2P-RPL route discovery may fail even though a route otherwise, the P2P-RPL route discovery may fail even though a route
exists that is much better than the one currently being used. exists that is much better than the one currently being used.
This document specifies a mechanism that enables an RPL router to This document specifies a mechanism that enables a RPL router to
measure the aggregated values of the routing metrics along an measure the aggregated values of the routing metrics along an
existing route to another RPL router in an LLN, thereby allowing the existing route to another RPL router in an LLN, thereby allowing the
router to decide if it wants to discover a better route using P2P-RPL router to decide if it wants to discover a better route using P2P-RPL
and determine the routing constraints to be used for this purpose. and determine the routing constraints to be used for this purpose.
Thus, the utility of this mechanism is dependent on the existence of Thus, the utility of this mechanism is dependent on the existence of
P2P-RPL, which is targeting publication as an Experimental RFC. It P2P-RPL [RFC6997]. The hope is that experiments with P2P-RPL and the
makes sense, therefore, for this document also to target publication mechanism defined in this document will result in feedback on the
as an Experimental RFC. The hope is that experiments with P2P-RPL utility and benefits of this document, so that a Standards Track
and the mechanism defined in this document will result in feedback on version of this document can then be developed.
the utility and benefits of this document and it will be revised and
progressed on the Standards Track based on this feedback.
1.1. Terminology 1.1. 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
[RFC2119]. [RFC2119].
This document uses terminology from [RFC6550], Additionally, this document uses terminology from [RFC6550],
[I-D.ietf-roll-terminology] and [I-D.ietf-roll-p2p-rpl]. [RFC6554], and [RFC6997]. Further terminology may be found in
Additionally, this document defines the following terms. [ROLL-TERMS]. This document defines the following terms:
Start Point: The Start Point refers to the RPL router that initiates Start Point: The RPL router that initiates the measurement process
the measurement process defined in this document and is the start defined in this document and that is the start point of the P2P
point of the P2P route being measured. route being measured.
End Point: The End Point refers to the RPL router at the end point of End Point: The RPL router at the end point of the P2P route being
the P2P route being measured. measured.
Intermediate Point: An RPL router, other than the Start Point and the Intermediate Point: A RPL router, other than the Start Point and the
End Point, on the P2P route being measured. End Point, on the P2P route being measured.
The following terms, already defined in [I-D.ietf-roll-p2p-rpl], have The following terms, as already defined in [RFC6997], are redefined
been redefined in this document in the following manner. in this document in the following manner:
Forward direction: The direction from the Start Point to the End Forward direction: The direction from the Start Point to the
Point. End Point.
Reverse direction: The direction from the End Point to the Start Reverse direction: The direction from the End Point to the
Point. Start Point.
2. Overview 2. Overview
The mechanism described in this document can be used by a Start Point The mechanism described in this document can be used by a Start Point
in an LLN to measure the aggregated values of selected routing in an LLN to measure the aggregated values of selected routing
metrics along a P2P route to an End Point within the LLN. The route metrics along a P2P route to an End Point within the LLN. The route
is measured in the Forward direction. Such a route could be a Source is measured in the Forward direction. Such a route could be a Source
Route or a Hop-by-hop Route established using RPL [RFC6550] or P2P- Route or a Hop-by-hop Route established using RPL [RFC6550] or
RPL [I-D.ietf-roll-p2p-rpl]. Such a route could also be a "mixed" P2P-RPL [RFC6997]. Such a route could also be a "mixed" route, with
route with the initial part consisting of hop-by-hop ascent to the the initial part consisting of hop-by-hop ascent to the root of a
root of a non-storing DAG [RFC6550] and the final part consisting of non-storing DAG [RFC6550] and the final part consisting of a source-
a source-routed descent to the End Point. The Start Point decides routed descent to the End Point. The Start Point decides what
what metrics to measure and sends a Measurement Request message, metrics to measure and sends a Measurement Request message, carrying
carrying the desired routing metric objects, along the route. If a the desired routing metric objects, along the route. If a Source
Source Route is being measured, the Measurement Request carries the Route is being measured, the Measurement Request carries the route
route inside an Address vector. If a Hop-by-hop Route is being inside an Address vector. If a Hop-by-hop Route is being measured,
measured, the Measurement Request identifies the route by its the Measurement Request identifies the route by its RPLInstanceID
RPLInstanceID [RFC6550] (and, in case the RPLInstanceID is a local [RFC6550] (and, if the RPLInstanceID is a local value, the
value, the Start Point's IPv6 address associated with the route). On Start Point's IPv6 address associated with the route). On receiving
receiving a Measurement Request, an Intermediate Point updates the a Measurement Request, an Intermediate Point updates the routing
routing metric values inside the message and forwards it to the next metric values inside the message and forwards it to the next hop on
hop on the route. Thus, the Measurement Request accumulates the the route. Thus, the Measurement Request accumulates the values of
values of the routing metrics for the complete route as it travels the routing metrics for the complete route as it travels towards the
towards the End Point. Upon receiving the Measurement Request, the End Point. Upon receiving the Measurement Request, the End Point
End Point unicasts a Measurement Reply message, carrying the unicasts a Measurement Reply message, carrying the accumulated values
accumulated values of the routing metrics, back to the Start Point. of the routing metrics, back to the Start Point. Optionally, the
Optionally, the Start Point may allow an Intermediate Point to Start Point may allow an Intermediate Point to generate the
generate the Measurement Reply if the Intermediate Point already Measurement Reply if the Intermediate Point already knows the
knows the relevant routing metric values along rest of the route. relevant routing metric values along the rest of the route.
The Measurement Request may include an Address vector that serves one The Measurement Request may include an Address vector that serves one
of the following functions: of the following functions:
o To accumulate a Source Route for End Point's use: If a Hop-by-hop o To accumulate a Source Route for the End Point's use: If a Hop-by-
Route with a local RPLInstanceID is being measured, the Start hop Route with a local RPLInstanceID is being measured, the
Point may require each Intermediate Point to add its global or Start Point may require that each Intermediate Point add its
unique local IPv6 address to an Address vector inside the global or unique-local IPv6 address to an Address vector inside
Measurement Request. The Source Route, thus accumulated, can be the Measurement Request. The Source Route, thus accumulated, can
used by the End Point to reach the Start Point. In particular, be used by the End Point to reach the Start Point. In particular,
the End Point may use the accumulated Source Route to send the the End Point may use the accumulated Source Route to send the
Measurement Reply back to the Start Point. In this case, the Measurement Reply back to the Start Point. In this case, the
Start Point includes a suitably-sized Address vector in the Start Point includes a suitably sized Address vector in the
Measurement Request. The size of the Address vector puts a hard Measurement Request. The size of the Address vector puts a hard
limit on the length of the accumulated route. An Intermediate limit on the length of the accumulated route. An Intermediate
Point is not allowed to modify the size of the Address vector and Point is not allowed to modify the size of the Address vector and
must discard a received Measurement Request if the Address vector must discard a received Measurement Request if the Address vector
is not large enough to contain the complete route. is not large enough to contain the complete route.
o To carry the Source Route being measured: The Start Point may o To carry the Source Route being measured: The Start Point may
insert an Address vector inside the Measurement Request to carry insert an Address vector inside the Measurement Request to carry
the Source Route being measured. Also, the root of a global non- the Source Route being measured. Also, the root of a global
storing DAG may insert an Address vector, carrying a Source Route non-storing DAG may insert an Address vector, carrying a Source
from itself to the End Point, inside a Measurement Request message Route from itself to the End Point, inside a Measurement Request
if this message had been traveling along this DAG so far. This message if this message had been traveling along this DAG so far.
Source Route must consist of global or unique local IPv6 This Source Route must consist of global or unique-local IPv6
addresses. An Intermediate Point is not allowed to modify an addresses. An Intermediate Point is not allowed to modify an
existing Address vector before forwarding the Measurement Request existing Address vector before forwarding the Measurement Request
further. In other words, an Intermediate Point must not modify further. In other words, an Intermediate Point must not modify
the Source Route along which the Measurement Request is currently the Source Route along which the Measurement Request is currently
traveling. traveling.
3. The Measurement Object (MO) 3. The Measurement Object (MO)
This document defines two new RPL Control Message types, the This document defines two new RPL control message types: the
Measurement Object (MO), with code TBD1, and the Secure MO, with code Measurement Object (MO), with code 0x06; and the Secure MO, with
TBD2. An MO serves as both Measurement Request and Measurement code 0x86. An MO serves as both Measurement Request and
Reply. Measurement Reply.
3.1. Format of the base MO 3.1. Format of the Base MO
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RPLInstanceID | Compr |T|H|A|R|B|I| SeqNo | Num | Index | | RPLInstanceID | Compr |T|H|A|R|B|I| SeqNo | Num | Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Start Point Address . . Start Point Address .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. End Point Address . . End Point Address .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Address[0..Num-1] . . Address[0..Num-1] .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Metric Container Option(s) . . Metric Container Option(s) .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Format of the base Measurement Object (MO) Figure 1: Format of the Base Measurement Object (MO)
The format of a base MO is shown in Figure 1. A base MO consists of The format of a base MO is shown in Figure 1. A base MO consists of
the following fields: the following fields:
o RPLInstanceID: This field specifies the RPLInstanceID of the Hop- o RPLInstanceID: This field specifies the RPLInstanceID of the
by-hop Route along which the Measurement Request travels (or Hop-by-hop Route along which the Measurement Request travels
traveled initially until it switched over to a Source Route). (or traveled initially until it switched over to a Source Route).
o Compr: In many LLN deployments, IPv6 addresses share a well known, o Compr: In many LLN deployments, IPv6 addresses share a well-known,
common prefix. In such cases, the common prefix can be elided common prefix. In such cases, the common prefix can be elided
when specifying IPv6 addresses in the Start Point/End Point when specifying IPv6 addresses in the Start Point/End Point
Address fields and the Address vector. The "Compr" field, a 4-bit Address fields and the Address vector. The "Compr" field, a 4-bit
unsigned integer, is set by the Start Point to specify the number unsigned integer, is set by the Start Point to specify the number
of prefix octets that are elided from the IPv6 addresses in Start of prefix octets that are elided from the IPv6 addresses in
Point/End Point Address fields and the Address vector. The Start Start Point/End Point Address fields and the Address vector. The
Point will set the Compr value to zero if full IPv6 addresses are Start Point will set the Compr value to zero if full IPv6
to be carried in the Start Point Address/End Point Address fields addresses are to be carried in the Start Point Address/End Point
and the Address vector. Address fields and the Address vector.
o Type (T): This flag is set to one if the MO represents a o Type (T): This flag is set to one if the MO represents a
Measurement Request. The flag is set to zero if the MO is a Measurement Request. The flag is set to zero if the MO is a
Measurement Reply. Measurement Reply.
o Hop-by-hop (H): The Start Point MUST set this flag to one if (at o Hop-by-hop (H): The Start Point MUST set this flag to one if (at
least the initial part of) the route being measured is hop-by-hop. least the initial part of) the route being measured is hop by hop.
In that case, the Hop-by-hop Route is identified by the In that case, the Hop-by-hop Route is identified by the
RPLInstanceID, the End Point Address and, if the RPLInstanceID is RPLInstanceID, the End Point Address, and, if the RPLInstanceID is
a local value, the Start Point Address fields inside the a local value, the Start Point Address fields inside the
Measurement Request. Here, the Start Point Address field is Measurement Request. Here, the Start Point Address field is
required to be same as the DODAGID (the identifier of the required to be the same as the DODAGID (the identifier of the
destination-oritented DAG root) [RFC6550] of the route being Destination-Oriented DAG (DODAG) root) [RFC6550] of the route
measured. The Start Point MUST set the H flag to zero if the being measured. The Start Point MUST set the H flag to zero if
route being measured is a Source Route specified in the Address the route being measured is a Source Route specified in the
vector. An Intermediate Point MUST set the H flag in an outgoing Address vector. An Intermediate Point MUST set the H flag in an
Measurement Request to the same value that it had in the outgoing Measurement Request to the same value that it had in the
corresponding incoming Measurement Request unless it is the root corresponding incoming Measurement Request, except under the
of the non-storing global DAG, identified by the RPLInstanceID, following circumstance: If the Intermediate Point is the root of
along which the Measurement Request had been traveling so far and the non-storing global DAG along which the Measurement Request had
the Intermediate Point intends to insert a Source Route inside the been traveling so far and it intends to insert a Source Route
Address vector to direct it towards the End Point. In that case, inside the Address vector to direct the Measurement Request
the Intermediate Point MUST set the H flag to zero. towards the End Point, then it MUST set the H flag to zero.
o Accumulate Route (A): A value 1 in this flag indicates that the o Accumulate Route (A): A value of 1 in this flag indicates that the
Measurement Request is accumulating a Source Route for use by the Measurement Request is accumulating a Source Route for use by the
End Point to send the Measurement Reply back to the Start Point. End Point to send the Measurement Reply back to the Start Point.
Route accumulation MUST NOT be used (i.e., this flag MUST NOT be Route accumulation MUST NOT be used (i.e., this flag MUST NOT be
set to 1) inside a Measurement Request unless it travels along a set to one) inside a Measurement Request, unless it travels along
Hop-by-hop Route represented by a local RPLInstanceID (i.e., H = a Hop-by-hop Route represented by a local RPLInstanceID (i.e., H =
1, RPLInstanceID has a local value). Route accumulation MAY be 1 and RPLInstanceID has a local value). Route accumulation MAY be
used (i.e., this flag MAY be set to 1) if the Measurement Request used (i.e., this flag MAY be set to one) if the Measurement
is traveling along a Hop-by-hop Route with a local RPLInstanceID. Request is traveling along a Hop-by-hop Route with a local
In this case if the route accumulation is on, an Intermediate RPLInstanceID. In this case, if the route accumulation is on, an
Point adds its unicast global/unique-local IPv6 address (after Intermediate Point adds its unicast global/unique-local IPv6
eliding Compr number of prefix octets) to the Address vector in address (after eliding Compr number of prefix octets) to the
the manner specified in Section 5.3. In other cases, this flag Address vector in the manner specified in Section 5.3. In other
MUST be set to zero on transmission and ignored on reception. cases, this flag MUST be set to zero on transmission and ignored
Route accumulation is not allowed when the Measurement Request on reception. Route accumulation is not allowed when the
travels along a Hop-by-hop Route with a global RPLInstanceID, Measurement Request travels along a Hop-by-hop Route with a global
i.e., along a global DAG, because: RPLInstanceID, i.e., along a global DAG, because:
* The DAG's root may need the Address vector to insert a Source * The DAG's root may need the Address vector to insert a Source
Route to the End Point; and Route to the End Point; and
* The End Point can presumably reach the Start Point along this * The End Point can presumably reach the Start Point along this
global DAG (identified by the RPLInstanceID field). global DAG (identified by the RPLInstanceID field).
o Reverse (R): A value 1 in this flag inside a Measurement Request o Reverse (R): A value of 1 in this flag inside a Measurement
indicates that the Address vector contains a complete Source Route Request indicates that the Address vector contains a complete
from the Start Point to the End Point, which can be used, after Source Route from the Start Point to the End Point, which can be
reversal, by the End Point to send the Measurement Reply back to used, after reversal, by the End Point to send the Measurement
the Start Point. This flag MAY be set to one inside a Measurement Reply back to the Start Point. This flag MAY be set to one inside
Request only if a Source Route, from the Start Point to the End a Measurement Request only if a Source Route, from the Start Point
Point, is being measured. Otherwise, this flag MUST be set to to the End Point, is being measured. Otherwise, this flag MUST be
zero on transmission and ignored on reception. set to zero on transmission and ignored on reception.
o Back Request (B): A value 1 in this flag serves as a request to o Back Request (B): A value of 1 in this flag serves as a request to
the End Point to send a Measurement Request towards the Start the End Point to send a Measurement Request towards the
Point. On receiving a Measurement Request with the B flag set to Start Point. On receiving a Measurement Request with the B flag
one, the End Point SHOULD generate a Measurement Request to set to one, the End Point SHOULD generate a Measurement Request to
measure the cost of its current (or the most preferred) route to measure the cost of its current (or the most preferred) route to
the Start Point. Receipt of this Measurement Request would allow the Start Point. Receipt of this Measurement Request would allow
the Start Point to know the cost of the back route from the End the Start Point to know the cost of the back route from the
Point to itself and thus determine the round-trip cost of reaching End Point to itself and thus determine the round-trip cost of
the End Point. reaching the End Point.
o Intermediate Reply (I): A value 1 in this flag serves as a o Intermediate Reply (I): A value of 1 in this flag serves as
permission to an Intermediate Point to generate a Measurement permission to an Intermediate Point to generate a Measurement
Reply if it knows the aggregated values of the routing metrics Reply if it knows the aggregated values of the routing metrics
being measured for the rest of the route. Setting this flag to being measured for the rest of the route. Setting this flag to
one may be useful in scenarios where the Hop Count [RFC6551] is one may be useful in scenarios where the Hop Count [RFC6551] is
the routing metric of interest and an Intermediate Point (e.g. the the routing metric of interest and an Intermediate Point (e.g.,
root of a non-storing global DAG or a common ancestor of the Start the root of a non-storing global DAG or a common ancestor of the
Point and the End Point in a storing global DAG) may know the Hop Start Point and the End Point in a storing global DAG) may know
Count of the remainder of the route to the End Point. This flag the Hop Count of the remainder of the route to the End Point.
MAY be set to one only if a Hop-by-hop Route with a global This flag MAY be set to one only if a Hop-by-hop Route with a
RPLInstanceID is being measured (i.e., H = 1, RPLInstanceID has a global RPLInstanceID is being measured (i.e., H = 1 and
global value). Otherwise, this flag MUST be set to zero on RPLInstanceID has a global value). Otherwise, this flag MUST be
transmission and ignored on reception. set to zero on transmission and ignored on reception.
o SeqNo: A 6-bit sequence number, assigned by the Start Point, that o SeqNo: This is a 6-bit sequence number, assigned by the
allows the Start Point to uniquely identify a Measurement Request Start Point, that allows the Start Point to uniquely identify a
and the corresponding Measurement Reply. Measurement Request and the corresponding Measurement Reply.
o Num: This field indicates the number of elements, each (16 - o Num: This field indicates the number of elements, each
Compr) octets in size, inside the Address vector. If the value of (16 - Compr) octets in size, inside the Address vector. If the
this field is zero, the Address vector is not present in the MO. value of this field is zero, the Address vector is not present in
the MO.
o Index: If the Measurement Request is traveling along a Source o Index: If the Measurement Request is traveling along a Source
Route contained in the Address vector (i.e., H = 0), this field Route contained in the Address vector (i.e., H = 0), this field
indicates the index in the Address vector of the next hop on the indicates the index in the Address vector of the next hop on the
route. If the Measurement Request is traveling along a Hop-by-hop route. If the Measurement Request is traveling along a Hop-by-hop
Route with a local RPLInstanceID and the Route Accumulation is on Route with a local RPLInstanceID and the route accumulation is on
(i.e., H = 1, RPLInstanceID has a local value, A = 1), this field (i.e., H = 1, RPLInstanceID has a local value, and A = 1), this
indicates the index in the Address vector where an Intermediate field indicates the index in the Address vector where an
Point receiving the Measurement Request must store its IPv6 Intermediate Point receiving the Measurement Request must store
address. Otherwise, this field MUST be set to zero on its IPv6 address. Otherwise, this field MUST be set to zero on
transmission and ignored on reception. transmission and ignored on reception.
o Start Point Address: A unicast global or unique local IPv6 address o Start Point Address: This is a unicast global or unique-local IPv6
of the Start Point after eliding Compr number of prefix octets. address of the Start Point after eliding Compr number of prefix
If the Measurement Request is traveling along a Hop-by-hop Route octets. If the Measurement Request is traveling along a Hop-by-
and the RPLInstanceID field indicates a local value, the Start hop Route and the RPLInstanceID field indicates a local value, the
Point Address field MUST specify the DODAGID value that, along Start Point Address field MUST specify the DODAGID value that,
with the RPLInstanceID and the End Point Address, uniquely along with the RPLInstanceID and the End Point Address, uniquely
identifies the Hop-by-hop Route being measured. identifies the Hop-by-hop Route being measured.
o End Point Address: A unicast global or unique local IPv6 address o End Point Address: This is a unicast global or unique-local IPv6
of the End Point after eliding Compr number of prefix octets. address of the End Point after eliding Compr number of prefix
octets.
o Address[0..Num-1]: A vector of unicast global or unique local IPv6 o Address[0..Num-1]: This field is a vector of unicast global or
addresses (with Compr number of prefix octets elided) representing unique-local IPv6 addresses (with Compr number of prefix octets
a Source Route: elided) representing a Source Route:
* Each element in the vector has size (16 - Compr) octets. * Each element in the vector has size (16 - Compr) octets.
* The total number of elements inside the Address vector is given * The total number of elements inside the Address vector is given
by the Num field. by the Num field.
* The Start Point and End Point addresses MUST NOT be included in * The Start Point and End Point addresses MUST NOT be included in
the Address vector. the Address vector.
* The Address vector MUST NOT contain any multicast addresses. * The Address vector MUST NOT contain any multicast addresses.
* If the Start Point wants to measure a Hop-by-hop Route with a * If the Start Point wants to measure a Hop-by-hop Route with a
local RPLInstanceID and accumulate a Source Route for the End local RPLInstanceID and accumulate a Source Route for the
Point's use (i.e., the Measurement Request has the H flag set End Point's use (i.e., the Measurement Request has the H flag
to 1, RPLInstanceID set to a local value and the A flag set to set to one, RPLInstanceID set to a local value, and the A flag
1), it MUST include a suitably-sized Address vector in the set to one), it MUST include a suitably sized Address vector in
Measurement Request. As the Measurement Request travels over the Measurement Request. As the Measurement Request travels
the route being measured, the Address vector accumulates a over the route being measured, the Address vector accumulates a
Source Route that can be used by the End Point, after reversal, Source Route that can be used by the End Point, after reversal,
to reach (and, in particular, to send the Measurement Reply to reach (and, in particular, to send the Measurement Reply
back to) the Start Point. The route MUST be accumulated in the back to) the Start Point. The route MUST be accumulated in the
Forward direction but the IPv6 addresses in the accumulated Forward direction, but the IPv6 addresses in the accumulated
route MUST be reachable in the Reverse direction. An route MUST be reachable in the Reverse direction. An
Intermediate Point MUST add only a global or unique local IPv6 Intermediate Point MUST add only a global or unique-local IPv6
address to the Address vector and MUST NOT modify the size of address to the Address vector and MUST NOT modify the size of
the Address vector. the Address vector.
* If the Start Point wants to measure a Source Route, it MUST * If the Start Point wants to measure a Source Route, it MUST
include an Address vector, containing the route being measured, include an Address vector, containing the route being measured,
inside the Measurement Request. Similarly, if the Measurement inside the Measurement Request. Similarly, if the Measurement
Request had been traveling along a global non-storing DAG so Request had been traveling along a global non-storing DAG so
far, the root of this DAG may insert an Address vector, far, the root of this DAG may insert an Address vector,
containing a Source Route from itself to the End Point, inside containing a Source Route from itself to the End Point, inside
the Measurement Request. In both cases, the Source Route the Measurement Request. In both cases, the Source Route
inside the Address vector MUST consist only of global or unique inside the Address vector MUST consist only of global or
local IPv6 addresses that are reachable in the Forward unique-local IPv6 addresses that are reachable in the Forward
direction. Further, in both cases, an Intermediate Point MUST direction. Further, in both cases, an Intermediate Point MUST
NOT modify the contents of the existing Address vector before NOT modify the contents of the existing Address vector before
forwarding the Measurement Request further. In other words, an forwarding the Measurement Request further. In other words, an
Intermediate Point MUST NOT modify the Source Route along which Intermediate Point MUST NOT modify the Source Route along which
the Measurement Request is currently traveling. The Start the Measurement Request is currently traveling. The
Point MAY set the R flag in the Measurement Request to one if Start Point MAY set the R flag in the Measurement Request to
the Source Route inside the Address vector can be used by the one if the Source Route inside the Address vector can be used
End Point, after reversal, to reach (and, in particular, to by the End Point, after reversal, to reach (and, in particular,
send the Measurement Reply back to) the Start Point. In other to send the Measurement Reply back to) the Start Point. In
words, the Start Point MAY set the R flag to one only if all other words, the Start Point MAY set the R flag to one only if
the IPv6 addresses in the Address vector are reachable in the all the IPv6 addresses in the Address vector are reachable in
Reverse direction. the Reverse direction.
o Metric Container Options: A Measurement Request MUST contain one o Metric Container Options: A Measurement Request MUST contain one
or more Metric Container options [RFC6550] to accumulate the or more Metric Container options [RFC6550] to accumulate the
values of the selected routing metrics in the manner described in values of the selected routing metrics in the manner described in
[RFC6551] for the route being measured. [RFC6551] for the route being measured.
Section 4 describes how a Start Point sets various fields inside a Section 4 describes how a Start Point sets various fields inside a
Measurement Request in different cases. Section 5 describes how an Measurement Request in different cases. Section 5 describes how an
Intermediate Point processes a received Measurement Request before Intermediate Point processes a received Measurement Request before
forwarding it further. Section 6 describes how the End Point forwarding it further. Section 6 describes how the End Point
processes a received Measurement Request and generate a Measurement processes a received Measurement Request and generates a Measurement
Reply. Finally, Section 7 describes how the Start Point processes a Reply. Finally, Section 7 describes how the Start Point processes a
received Measurement Reply. In the following discussion, any received Measurement Reply. In the following discussion, any
reference to discarding a received Measurement Request/Reply with "no reference to discarding a received Measurement Request/Reply with "no
further processing" does not preclude updating the appropriate error further processing" does not preclude updating the appropriate error
counters or any similar actions. counters or any similar actions.
3.2. Secure MO 3.2. Secure MO
A Secure MO follows the format in Figure 7 of [RFC6550], where the A Secure MO follows the format shown in Figure 7 of [RFC6550], where
base format is the base MO shown in Figure 1. Sections 6.1, 10 and the base format is the base MO shown in Figure 1. Sections 6.1, 10,
19 of [RFC6550] describe RPL security framework. These sections are and 19 of [RFC6550] describe the RPL security framework. These
applicable to the use of Secure MO messages as well except as sections are applicable to the use of Secure MO messages as well,
constrained in this section. An LLN deployment MUST support the use except as constrained in this section. An LLN deployment MUST
of Secure MO messages so that it has the ability to invoke RPL- support the use of Secure MO messages so that it has the ability to
provided security mechanisms and prevent misuse of the measurement invoke RPL-provided security mechanisms and prevent misuse of the
mechanism by unauthorized routers. measurement mechanism by unauthorized routers.
The Start Point determines whether Secure MO messages are to be used The Start Point determines whether Secure MO messages are to be used
in a particular route measurement and if yes the Security in a particular route measurement and, if yes, the Security
Configuration (see definition in [I-D.ietf-roll-p2p-rpl]) to be used Configuration (see definition in [RFC6997]) to be used for that
for the purpose. The Start Point MUST NOT set the "Key Identifier purpose. The Start Point MUST NOT set the "Key Identifier Mode"
Mode" field to value 1 inside this Security Configuration since this field to a value of 1 inside this Security Configuration, since this
setting indicates the use of a per-pair key which is not suitable for setting indicates the use of a per-pair key, which is not suitable
securing the Measurement Request messages that travel over multiple for securing the Measurement Request messages that travel over
hops. A router (an Intermediate Point or the End Point), multiple hops. A router (an Intermediate Point or the End Point)
participating in a particular route measurement, participating in a particular route measurement
o MUST generate a Secure MO message (a Measurement Request or a o MUST generate a Secure MO message (a Measurement Request or a
Measurement Reply) if the received Measurement Request is a Secure Measurement Reply) if the received Measurement Request is a Secure
MO. The Security Configuration used in generating a Secure MO MO. The Security Configuration used in generating a Secure MO
message MUST be same as the one used in the received message. message MUST be the same as the one used in the received message.
o MUST NOT generate a Secure MO message if the received Measurement o MUST NOT generate a Secure MO message if the received Measurement
Request is not a Secure MO. Request is not a Secure MO.
A router MUST discard a received Measurement Request if it cannot A router MUST discard a received Measurement Request if it cannot
follow the above mentioned rules. If the Start Point sends a follow the above-mentioned rules. If the Start Point sends a
Measurement Request in a Secure MO message using a particular Measurement Request in a Secure MO message using a particular
Security Configuration, it MUST discard the corresponding Measurement Security Configuration, it MUST discard the corresponding Measurement
Reply it receives with no further processing unless the Measurement Reply it receives with no further processing, unless the Measurement
Reply is received in a Secure MO message generated with same Security Reply is received in a Secure MO message generated with the same
Configuration as the one used in the Measurement Request. Security Configuration as the one used in the Measurement Request.
In the following discussion, any reference to an MO message is also In the following discussion, any reference to an MO message is also
applicable to a Secure MO message unless noted otherwise. applicable to a Secure MO message, unless noted otherwise.
4. Originating a Measurement Request 4. Originating a Measurement Request
A Start Point sets various fields inside the Measurement Request it A Start Point sets various fields inside the Measurement Request it
generates in the manner described below. The Start Point MUST also generates in the manner described below. The Start Point MUST also
include the routing metric objects [RFC6551] of interest inside one include the routing metric objects [RFC6551] of interest inside one
or more Metric Container options inside the Measurement Request. The or more Metric Container options inside the Measurement Request. The
Start Point then determines the next hop on the route being measured. Start Point then determines the next hop on the route being measured.
If a Hop-by-hop route is being measured (i.e., H = 1), the next hop If a Hop-by-hop Route is being measured (i.e., H = 1), the next hop
is determined using the RPLInstanceID, the End Point Address and, if is determined using the RPLInstanceID, the End Point Address, and, if
RPLInstanceID is a local value, the Start Point Address fields in the RPLInstanceID is a local value, the Start Point Address fields in the
Measurement Request. If a Source Route is being measured (i.e., H = Measurement Request. If a Source Route is being measured (i.e.,
0), the Address[0] element inside the Measurement Request contains H = 0), the Address[0] element inside the Measurement Request
the next hop address. The Start Point MUST ensure that contains the next-hop address. The Start Point MUST ensure that
o the next hop address is a unicast address; and
o the next hop is on-link; and o the next-hop address is a unicast address, and
o the next hop is in the same RPL routing domain o the next hop is on-link, and
[I-D.ietf-roll-terminology] as the Start Point; o the next hop is in the same RPL routing domain [RFC6554] as the
Start Point,
failing which the Start Point MUST discard the Measurement Request failing which the Start Point MUST discard the Measurement Request
without sending. Depending on the routing metrics, the Start Point without sending. Depending on the routing metrics, the Start Point
must initiate the routing metric objects inside the Metric Container must initiate the routing metric objects inside the Metric Container
options by including the routing metric values for the first hop on options by including the routing metric values for the first hop on
the route being measured. Finally, the Start Point MUST unicast the the route being measured. Finally, the Start Point MUST unicast the
Measurement Request to the next hop on the route being measured. Measurement Request to the next hop on the route being measured.
The Start Point MUST maintain state for just transmitted Measurement The Start Point MUST maintain state for a just-transmitted
Request for a life time duration that is large enough to allow the Measurement Request, for a lifetime duration that is large enough to
corresponding Measurement Reply to return. This state consists of allow the corresponding Measurement Reply to return. This state
the RPLInstanceID, the SeqNo and the End Point Address fields of the consists of the RPLInstanceID, the SeqNo, and the End Point Address
Measurement Request. The life time duration for this state is fields of the Measurement Request. The lifetime duration for this
locally determined by the Start Point and may be deployment specific. state is locally determined by the Start Point and may be deployment
This state expires when the corresponding Measurement Reply is specific. This state expires when the corresponding Measurement
received or when the life time is over, whichever occurs first. Reply is received or when the lifetime is over, whichever occurs
Failure to receive the corresponding Measurement Reply before the first. Failure to receive the corresponding Measurement Reply before
expiry of a state may occur due to a number of reasons including the expiry of a state may occur due to a number of reasons, including
unwillingness on part of an Intermediate Point or the End Point to the unwillingness on the part of an Intermediate Point or the
process the Measurement Request. The Start Point should take such End Point to process the Measurement Request. The Start Point should
possibilities in account when deciding whether to generate another take such possibilities into account when deciding whether to
Measurement Request for this route. The Start Point MUST discard a generate another Measurement Request for this route. The Start Point
received Measurement Reply with no further processing if the state MUST discard a received Measurement Reply with no further processing
for the corresponding Measurement Request has already expired. if the state for the corresponding Measurement Request has already
expired.
4.1. When Measuring A Hop-by-hop Route with a Global RPLInstanceID 4.1. When Measuring a Hop-by-Hop Route with a Global RPLInstanceID
If a Hop-by-hop Route with a global RPLInstanceID is being measured If a Hop-by-hop Route with a global RPLInstanceID is being measured
(i.e., H = 1, RPLInstanceID has a global value), the MO MUST NOT (i.e., H = 1 and RPLInstanceID has a global value), the MO MUST NOT
contain an Address vector and various MO fields MUST be set in the contain an Address vector, and various MO fields MUST be set in the
following manner: following manner:
o RPLInstanceID: MUST be set to the RPLInstanceID of the route being o RPLInstanceID: This field MUST be set to the RPLInstanceID of the
measured. route being measured.
o Compr: MUST be set to specify the number of prefix octets that are o Compr: This field MUST be set to specify the number of prefix
elided from the IPv6 addresses in Start Point/End Point Address octets that are elided from the IPv6 addresses in Start Point/
fields. End Point Address fields.
o Type (T): MUST be set to one since the MO represents a Measurement o Type (T): This flag MUST be set to one, since the MO represents a
Request. Measurement Request.
o Hop-by-hop (H): MUST be set to one. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be set to zero. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag MUST be set to zero. o Reverse (R): This flag MUST be set to zero.
o Back Request (B): This flag MAY be set to one to request the End o Back Request (B): This flag MAY be set to one to request that the
Point to send a Measurement Request to the Start Point. End Point send a Measurement Request to the Start Point.
o Intermediate Reply (I): This flag MAY be set to one if the Start o Intermediate Reply (I): This flag MAY be set to one if the
Point expects an Intermediate Point to know the values of the Start Point expects an Intermediate Point to know the values of
routing metrics being measured for the remainder of the route. the routing metrics being measured for the remainder of the route.
o SeqNo: Assigned by the Start Point so that it can uniquely o SeqNo: This is assigned by the Start Point so that it can uniquely
identify the Measurement Request and the corresponding Measurement identify the Measurement Request and the corresponding
Reply. Measurement Reply.
o Num: This field MUST be set to zero. o Num: This field MUST be set to zero.
o Index: This field MUST be set to zero. o Index: This field MUST be set to zero.
o Start Point Address: MUST be set to a unicast global/unique-local o Start Point Address: This field MUST be set to a unicast
IPv6 address of the Start Point after eliding Compr number of global/unique-local IPv6 address of the Start Point after eliding
prefix octets. Compr number of prefix octets.
o End Point Address: MUST be set to a unicast global/unique-local o End Point Address: This field MUST be set to a unicast
IPv6 address of the End Point after eliding Compr number of prefix global/unique-local IPv6 address of the End Point after eliding
octets. Compr number of prefix octets.
4.2. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With 4.2. When Measuring a Hop-by-Hop Route with a Local RPLInstanceID with
Route Accumulation Off Route Accumulation Off
If a Hop-by-hop Route with a local RPLInstanceID is being measured If a Hop-by-hop Route with a local RPLInstanceID is being measured
and the Start Point does not want the MO to accumulate a Source Route and the Start Point does not want the MO to accumulate a Source Route
for the End Point's use, the MO MUST NOT contain the Address vector for the End Point's use, the MO MUST NOT contain the Address vector,
and various MO fields MUST be set in the following manner: and various MO fields MUST be set in the following manner:
o RPLInstanceID: MUST be set to the RPLInstanceID of the route being o RPLInstanceID: This field MUST be set to the RPLInstanceID of the
measured. route being measured.
o Compr: MUST be set to specify the number of prefix octets that are o Compr: This field MUST be set to specify the number of prefix
elided from the IPv6 addresses in Start Point/End Point Address octets that are elided from the IPv6 addresses in Start Point/
fields. End Point Address fields.
o Type (T): MUST be set to one since the MO represents a Measurement o Type (T): This flag MUST be set to one, since the MO represents a
Request. Measurement Request.
o Hop-by-hop (H): MUST be set to one. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be set to zero. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag MUST be set to zero. o Reverse (R): This flag MUST be set to zero.
o Back Request (B): This flag MAY be set to one to request the End o Back Request (B): This flag MAY be set to one to request that the
Point to send a Measurement Request to the Start Point. End Point send a Measurement Request to the Start Point.
o Intermediate Reply (I): This flag MUST be set to zero. o Intermediate Reply (I): This flag MUST be set to zero.
o SeqNo: Assigned by the Start Point so that it can uniquely o SeqNo: This is assigned by the Start Point so that it can uniquely
identify the Measurement Request and the corresponding Measurement identify the Measurement Request and the corresponding
Reply. Measurement Reply.
o Num: This field MUST be set to zero. o Num: This field MUST be set to zero.
o Index: This field MUST be set to zero. o Index: This field MUST be set to zero.
o Start Point Address: This field MUST contain the DODAGID value o Start Point Address: This field MUST contain the DODAGID value
(after eliding Compr number of prefix octets) associated with the (after eliding Compr number of prefix octets) associated with the
route being measured. This DODAGID MUST also be a global or route being measured. This DODAGID MUST also be a global or
unique local IPv6 address of the Start Point. unique-local IPv6 address of the Start Point.
o End Point Address: MUST be set to a unicast global or unique local o End Point Address: This field MUST be set to a unicast global or
IPv6 address of the End Point after eliding Compr number of prefix unique-local IPv6 address of the End Point after eliding Compr
octets. number of prefix octets.
4.3. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With 4.3. When Measuring a Hop-by-Hop Route with a Local RPLInstanceID with
Route Accumulation On Route Accumulation On
If a Hop-by-hop Route with a local RPLInstanceID is being measured If a Hop-by-hop Route with a local RPLInstanceID is being measured
and the Start Point desires the MO to accumulate a Source Route for and the Start Point desires the MO to accumulate a Source Route for
the End Point to send the Measurement Reply message back, the MO MUST the End Point to send the Measurement Reply message back, the MO MUST
contain a suitably-sized Address vector and various MO fields MUST be contain a suitably sized Address vector, and various MO fields MUST
set in the following manner: be set in the following manner:
o RPLInstanceID: MUST be set to the RPLInstanceID of the route being o RPLInstanceID: This field MUST be set to the RPLInstanceID of the
measured. route being measured.
o Compr: MUST be set to specify the number of prefix octets that are o Compr: This field MUST be set to specify the number of prefix
elided from the IPv6 addresses in Start Point/End Point Address octets that are elided from the IPv6 addresses in Start Point/
fields and the Address vector. End Point Address fields and the Address vector.
o Type (T): MUST be set to one since the MO represents a Measurement o Type (T): This flag MUST be set to one, since the MO represents a
Request. Measurement Request.
o Hop-by-hop (H): MUST be set to one. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be set to one. o Accumulate Route (A): This flag MUST be set to one.
o Reverse (R): This flag MUST be set to zero. o Reverse (R): This flag MUST be set to zero.
o Back Request (B): This flag MAY be set to one to request the End o Back Request (B): This flag MAY be set to one to request that the
Point to send a Measurement Request to the Start Point. End Point send a Measurement Request to the Start Point.
o Intermediate Reply (I): This flag MUST be set to zero. o Intermediate Reply (I): This flag MUST be set to zero.
o SeqNo: Assigned by the Start Point so that it can uniquely o SeqNo: This is assigned by the Start Point so that it can uniquely
identify the Measurement Request and the corresponding Measurement identify the Measurement Request and the corresponding
Reply. Measurement Reply.
o Num: This field MUST specify the number of address elements, each o Num: This field MUST specify the number of address elements, each
(16 - Compr) octets in size, that can fit inside the Address (16 - Compr) octets in size, that can fit inside the Address
vector. vector.
o Index: This field MUST be set to zero to indicate the position in o Index: This field MUST be set to zero to indicate the position in
the Address vector where the next hop must store its IPv6 address. the Address vector where the next hop must store its IPv6 address.
o Start Point Address: This field MUST contain the DODAGID value o Start Point Address: This field MUST contain the DODAGID value
(after eliding Compr number of prefix octets) associated with the (after eliding Compr number of prefix octets) associated with the
route being measured. This DODAGID MUST also be a global or route being measured. This DODAGID MUST also be a global or
unique local IPv6 address of the Start Point. unique-local IPv6 address of the Start Point.
o End Point Address: MUST be set to a unicast global or unique local o End Point Address: This field MUST be set to a unicast global or
IPv6 address of the End Point after eliding Compr number of prefix unique-local IPv6 address of the End Point after eliding Compr
octets. number of prefix octets.
o Address vector: The Address vector must be large enough to o Address vector: The Address vector must be large enough to
accomodate a complete Source Route from the End Point to the Start accommodate a complete Source Route from the End Point to the
Point. All the bits in the Address vector field MUST be set to Start Point. All the bits in the Address vector field MUST be set
zero. to zero.
4.4. When Measuring A Source Route 4.4. When Measuring a Source Route
If a Source Route is being measured, the Start Point MUST set various If a Source Route is being measured, the Start Point MUST set various
MO fields in the following manner: MO fields in the following manner:
o RPLInstanceID: This field does not have any significance when a o RPLInstanceID: This field does not have any significance when a
Source Route is being measured and hence can be set to any value. Source Route is being measured and hence can be set to any value.
o Compr: MUST be set to specify the number of prefix octets that are o Compr: This field MUST be set to specify the number of prefix
elided from the IPv6 addresses in Start Point/End Point Address octets that are elided from the IPv6 addresses in Start Point/
fields and the Address vector. End Point Address fields and the Address vector.
o Type (T): MUST be set to one since the MO represents a Measurement o Type (T): This flag MUST be set to one, since the MO represents a
Request. Measurement Request.
o Hop-by-hop (H): MUST be set to zero. o Hop-by-hop (H): This flag MUST be set to zero.
o Accumulate Route (A): This flag MUST be set to zero. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag SHOULD be set to one if the Source Route in o Reverse (R): This flag SHOULD be set to one if the Source Route in
the Address vector can be reversed and used by the End Point to the Address vector can be reversed and used by the End Point to
send the Measurement Reply message back to the Start Point. send the Measurement Reply message back to the Start Point.
Otherwise, this flag MUST be set to zero. Otherwise, this flag MUST be set to zero.
o Back Request (B): This flag MAY be set to one to request the End o Back Request (B): This flag MAY be set to one to request that the
Point to send a Measurement Request to the Start Point. End Point send a Measurement Request to the Start Point.
o Intermediate Reply (I): This flag MUST be set to zero. o Intermediate Reply (I): This flag MUST be set to zero.
o SeqNo: Assigned by the Start Point so that it can uniquely o SeqNo: This is assigned by the Start Point so that it can uniquely
identify the Measurement Request and the corresponding Measurement identify the Measurement Request and the corresponding
Reply. Measurement Reply.
o Num: This field MUST specify the number of address elements, each o Num: This field MUST specify the number of address elements, each
(16 - Compr) octets in size, inside the Address vector. (16 - Compr) octets in size, inside the Address vector.
o Index: This field MUST be set to zero to indicate the position in o Index: This field MUST be set to zero to indicate the position in
the Address vector of the next hop on the route. the Address vector of the next hop on the route.
o Start Point Address: MUST be set to a unicast global or unique o Start Point Address: This field MUST be set to a unicast global or
local IPv6 address of the Start Point after eliding Compr number unique-local IPv6 address of the Start Point after eliding Compr
of prefix octets. number of prefix octets.
o End Point Address: MUST be set to a unicast global or unique local o End Point Address: This field MUST be set to a unicast global or
IPv6 address of the End Point after eliding Compr number of prefix unique-local IPv6 address of the End Point after eliding Compr
octets. number of prefix octets.
o Address vector: o Address vector:
* The Address vector MUST contain a complete Source Route from * The Address vector MUST contain a complete Source Route from
the Start Point to the End Point (excluding the Start Point and the Start Point to the End Point (excluding the Start Point and
the End Point). the End Point).
* Each address appearing in the Address vector MUST be a unicast * Each address appearing in the Address vector MUST be a unicast
global or unique local IPv6 address. Further, each address global or unique-local IPv6 address. Further, each address
MUST have the same prefix as the Start Point Address and the MUST have the same prefix as the Start Point Address and the
End Point Address. This prefix, whose length in octets is End Point Address. This prefix, whose length in octets is
specified in the Compr field, MUST be elided from each address. specified in the Compr field, MUST be elided from each address.
* The IPv6 addresses in the Address vector MUST be reachable in * The IPv6 addresses in the Address vector MUST be reachable in
the Forward direction. the Forward direction.
* If the R flag is set to one, the IPv6 addresses in the Address * If the R flag is set to one, the IPv6 addresses in the Address
vector MUST also be reachable in the Reverse direction. vector MUST also be reachable in the Reverse direction.
5. Processing a Measurement Request at an Intermediate Point 5. Processing a Measurement Request at an Intermediate Point
A router (an Intermediate Point or the End Point) MAY discard a A router (an Intermediate Point or the End Point) MAY discard a
received MO with no processing to meet any policy-related goal. Such received MO with no processing, in order to meet any policy-related
policy goals may include the need to reduce the router's CPU load or goals. Such policy goals may include the need to reduce the router's
to enhance its battery life or to prevent misuse of this mechanism by CPU load, or to enhance its battery life, or to prevent the misuse of
unauthorized nodes. this mechanism by unauthorized nodes.
A router MUST discard a received MO with no further processing if the A router MUST discard a received MO with no further processing if the
value in the Compr field inside the received message is more than value in the Compr field inside the received message is more than
what the router considers the length of the common prefix used in what the router considers to be the length of the common prefix used
IPv6 addresses in the LLN to be. in IPv6 addresses in the LLN.
On receiving an MO, if a router chooses to process the packet On receiving an MO, if a router chooses to process the packet
further, it MUST check if one of its IPv6 addresses is listed as further, it MUST determine whether or not one of its IPv6 addresses
either the Start Point or the End Point Address. If neither, the is listed as either the Start Point or the End Point Address. If
router considers itself an Intermediate Point and MUST process the not, the router considers itself an Intermediate Point and MUST
received MO in the following manner. process the received MO in the following manner.
An Intermediate Point MUST discard the packet with no further An Intermediate Point MUST discard the packet with no further
processing if the received MO is not a Measurement Request (i.e., T = processing if the received MO is not a Measurement Request (i.e.,
0). This is because the End Point unicasts a Measurement Reply T = 0). This is because the End Point unicasts a Measurement Reply
directly to the Start Point. So, the Intermediate Point treats a directly to the Start Point. So, the Intermediate Point treats a
transiting Measurement Reply as a data packet and not an RPL control transiting Measurement Reply as a data packet and not a RPL control
message. message.
Next, the Intermediate Point determines the type of the route being Next, the Intermediate Point determines the type of the route being
measured (by checking the values of the H flag and the RPLInstanceID measured (by checking the values of the H flag and the RPLInstanceID
field) and processes the received MO accordingly in the manner field) and processes the received MO accordingly, in the manner
specified next. specified next.
5.1. When Measuring A Hop-by-hop Route with a Global RPLInstanceID 5.1. When Measuring a Hop-by-Hop Route with a Global RPLInstanceID
If a Hop-by-hop Route with a global RPLInstanceID is being measured If a Hop-by-hop Route with a global RPLInstanceID is being measured
(i.e. H = 1 and RPLInstanceID has a global value), the Intermediate (i.e., H = 1 and RPLInstanceID has a global value), the Intermediate
Point MUST process the received Measurement Request in the following Point MUST process the received Measurement Request in the following
manner. manner.
If the Num field inside the received Measurement Request is not set If the Num field inside the received Measurement Request is not set
to zero, thereby implying that an Address vector is present, the to zero, thereby implying that an Address vector is present, the
Intermediate Point MUST discard the received message with no further Intermediate Point MUST discard the received message with no further
processing. processing.
If the Intermediate Reply (I) flag is set to one in the received If the Intermediate Reply (I) flag is set to one in the received
Measurement Request and the Intermediate Point knows the values of Measurement Request and the Intermediate Point knows the values of
the routing metrics, specified in the Metric Container options, for the routing metrics (as specified in the Metric Container options)
the remainder of the route, it MAY generate a Measurement Reply on for the remainder of the route, it MAY generate a Measurement Reply
the End Point's behalf in the manner specified in Section 6.1 (after on the End Point's behalf in the manner specified in Section 6.1
including in the Measurement Reply the relevant routing metric values (after including in the Measurement Reply the relevant routing metric
for the complete route being measured). Otherwise, the Intermediate values for the complete route being measured). Otherwise, the
Point MUST process the received message in the following manner. Intermediate Point MUST process the received message in the following
manner.
The Intermediate Point MUST determine the next hop on the route being The Intermediate Point MUST determine the next hop on the route being
measured using the RPLInstanceID and the End Point Address. If the measured using the RPLInstanceID and the End Point Address. If the
Intermediate Point is the root of the non-storing global DAG along Intermediate Point is the root of the non-storing global DAG along
which the received Measurement Request had been traveling so far, it which the received Measurement Request had been traveling so far, it
MUST process the received Measurement Request in the following MUST process the received Measurement Request in the following
manner: manner:
o If the router does not know how to reach the End Point, it MUST o If the router does not know how to reach the End Point, it MUST
discard the Measurement Request with no further processing and MAY discard the Measurement Request with no further processing and MAY
send an ICMPv6 Destination Unreachable (with Code 0 - No Route To send an ICMPv6 Destination Unreachable (with Code 0 -- No Route To
Destination) error message [RFC4443] to the Start Point. Destination) error message [RFC4443] to the Start Point.
o Otherwise, unless the router determines the End Point itself to be o Otherwise, unless the router determines the End Point itself to be
the next hop, the router MUST make the following changes in the the next hop, the router MUST make the following changes in the
received Measurement Request: received Measurement Request:
* Set the H, A, R and I flags to zero (the A and R flags should * Set the H, A, R, and I flags to zero (the A and R flags should
already be zero in the received message). already be zero in the received message).
* Leave remaining fields unchanged (the Num field would be * Leave the remaining fields unchanged (the Num field would be
modified in next steps). Note that the RPLInstanceID field modified in the next steps). Note that the RPLInstanceID field
identifies the non-storing global DAG along which the identifies the non-storing global DAG along which the
Measurement Request traveled so far. This information MUST be Measurement Request traveled so far. This information MUST be
preserved so that the End Point may use this DAG to send the preserved so that the End Point may use this DAG to send the
Measurement Reply back to the Start Point. Measurement Reply back to the Start Point.
* Insert a new Address vector inside the Measurement Request and * Insert a new Address vector inside the Measurement Request, and
specify a Source Route to the End Point inside the Address specify a Source Route to the End Point inside the Address
vector as per the following rules: vector as per the following rules:
+ The Address vector MUST contain a complete route from the + The Address vector MUST contain a complete route from the
router to the End Point (excluding the router and the End router to the End Point (excluding the router and the
Point); End Point).
+ Each address appearing in the Address vector MUST be a + Each address appearing in the Address vector MUST be a
unicast global or unique local IPv6 address. Further, each unicast global or unique-local IPv6 address. Further, each
address MUST have the same prefix as the Start Point Address address MUST have the same prefix as the Start Point Address
and the End Point Address. This prefix, whose length in and the End Point Address. This prefix, whose length in
octets is specified in the Compr field, MUST be elided from octets is specified in the Compr field, MUST be elided from
each address. each address.
+ The IPv6 addresses in the Address vector MUST be reachable + The IPv6 addresses in the Address vector MUST be reachable
in the Forward direction; in the Forward direction.
If the router cannot insert an Address vector satisfying the If the router cannot insert an Address vector satisfying the
rules mentioned above, it MUST discard the Measurement Request rules mentioned above, it MUST discard the Measurement Request
with no further processing and MAY send an ICMPv6 Destination with no further processing and MAY send an ICMPv6 Destination
Unreachable (with Code 0 - No Route To Destination) error Unreachable (with Code 0 -- No Route To Destination) error
message [RFC4443] to the Start Point. message [RFC4443] to the Start Point.
* Specify in the Num field the number of address elements in the * Specify in the Num field the number of address elements in the
Address vector. Address vector.
* Set the Index field to zero to indicate the position in the * Set the Index field to zero to indicate the position in the
Address vector of the next hop on the route. Thus, Address[0] Address vector of the next hop on the route. Thus, the
element contains the address of the next hop on the route. Address[0] element contains the address of the next hop on the
route.
The Intermediate Point MUST then complete the processing of the The Intermediate Point MUST then complete the processing of the
received Measurement Request as specified in Section 5.5. received Measurement Request as specified in Section 5.5.
5.2. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With 5.2. When Measuring a Hop-by-Hop Route with a Local RPLInstanceID with
Route Accumulation Off Route Accumulation Off
If a Hop-by-hop Route with a local RPLInstanceID is being measured If a Hop-by-hop Route with a local RPLInstanceID is being measured
and the route accumulation is off (i.e., H = 1, RPLInstanceID has a and the route accumulation is off (i.e., H = 1, RPLInstanceID has a
local value, A = 0), the Intermediate Point MUST process the received local value, and A = 0), the Intermediate Point MUST process the
Measurement Request in the following manner. received Measurement Request in the following manner.
If the Num field inside the received Measurement Request is not set If the Num field inside the received Measurement Request is not set
to zero, thereby implying that an Address vector is present, the to zero, thereby implying that an Address vector is present, the
Intermediate Point MUST discard the received message with no further Intermediate Point MUST discard the received message with no further
processing. processing.
The Intermediate Point MUST then determine the next hop on the route The Intermediate Point MUST then determine the next hop on the route
being measured using the RPLInstanceID, the End Point Address and the being measured using the RPLInstanceID, the End Point Address, and
Start Point Address (which represents the DODAGID of the route being the Start Point Address (which represents the DODAGID of the route
measured). If the Intermediate Point can not determine the next hop, being measured). If the Intermediate Point cannot determine the next
it MUST discard the Measurement Request with no further processing hop, it MUST discard the Measurement Request with no further
and MAY send an ICMPv6 Destination Unreachable (with Code 0 - No processing and MAY send an ICMPv6 Destination Unreachable (with
Route To Destination) error message [RFC4443] to the Start Point. Code 0 -- No Route To Destination) error message [RFC4443] to the
Otherwise, the Intermediate Point MUST complete the processing of the Start Point. Otherwise, the Intermediate Point MUST complete the
received Measurement Request as specified in Section 5.5. processing of the received Measurement Request as specified in
Section 5.5.
5.3. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With 5.3. When Measuring a Hop-by-Hop Route with a Local RPLInstanceID with
Route Accumulation On Route Accumulation On
If a Hop-by-hop Route with a local RPLInstanceID is being measured If a Hop-by-hop Route with a local RPLInstanceID is being measured
and the route accumulation is on (i.e., H = 1, RPLInstanceID has a and the route accumulation is on (i.e., H = 1, RPLInstanceID has a
local value, A = 1), the Intermediate Point MUST process the received local value, and A = 1), the Intermediate Point MUST process the
Measurement Request in the following manner. received Measurement Request in the following manner.
If the Num field inside the received Measurement Request is set to If the Num field inside the received Measurement Request is set to
zero, thereby implying that an Address vector is not present, the zero, thereby implying that an Address vector is not present, the
Intermediate Point MUST discard the received message with no further Intermediate Point MUST discard the received message with no further
processing. processing.
The Intermediate Point MUST then determine the next hop on the route The Intermediate Point MUST then determine the next hop on the route
being measured using the RPLInstanceID, the End Point Address and the being measured using the RPLInstanceID, the End Point Address, and
Start Point Address (which represents the DODAGID of the route being the Start Point Address (which represents the DODAGID of the route
measured). If the Intermediate Point can not determine the next hop, being measured). If the Intermediate Point cannot determine the next
it MUST discard the Measurement Request with no further processing hop, it MUST discard the Measurement Request with no further
and MAY send an ICMPv6 Destination Unreachable (with Code 0 - No processing and MAY send an ICMPv6 Destination Unreachable (with
Route To Destination) error message [RFC4443] to the Start Point. If Code 0 -- No Route To Destination) error message [RFC4443] to the
the index field has value Num - 1 and the next hop is not same as the Start Point. If the index field has value Num - 1 and the next hop
End Point, the Intermediate Point MUST drop the received Measurement is not the same as the End Point, the Intermediate Point MUST drop
Request with no further processing. In this case, the next hop would the received Measurement Request with no further processing. In this
have no space left in the Address vector to store its address. case, the next hop would have no space left in the Address vector to
Otherwise, the router MUST store one of its IPv6 addresses at store its address. Otherwise, the router MUST store one of its IPv6
location Address[Index] and then increment the Index field. The IPv6 addresses at location Address[Index] and then increment the Index
address added to the Address vector MUST have the following field. The IPv6 address added to the Address vector MUST have the
properties: following properties:
o This address MUST be a unicast global or unique local address. o This address MUST be a unicast global or unique-local address.
o This address MUST have the same prefix as the Start Point Address o This address MUST have the same prefix as the Start Point Address
and the End Point Address. This prefix, whose length in octets is and the End Point Address. This prefix, whose length in octets is
specified in the Compr field, MUST be elided before the address is specified in the Compr field, MUST be elided before the address is
added to the Address vector. added to the Address vector.
o This address MUST be reachable in the Reverse direction. o This address MUST be reachable in the Reverse direction.
If the router does not have an IPv6 address that satisfies the If the router does not have an IPv6 address that satisfies the
properties mentioned above, it MUST discard the Measurement Request properties mentioned above, it MUST discard the Measurement Request
with no further processing. with no further processing.
The Intermediate Point MUST then complete the processing of the The Intermediate Point MUST then complete the processing of the
received Measurement Request as specified in Section 5.5. received Measurement Request as specified in Section 5.5.
5.4. When Measuring A Source Route 5.4. When Measuring a Source Route
If a Source Route is being measured (i.e., H = 0), the Intermediate If a Source Route is being measured (i.e., H = 0), the Intermediate
Point MUST process the received Measurement Request in the following Point MUST process the received Measurement Request in the following
manner. manner.
If the Num field inside the received Measurement Request is set to If the Num field inside the received Measurement Request is set to
zero, thereby implying that an Address vector is not present, the zero, thereby implying that an Address vector is not present, the
Intermediate Point MUST discard the received message with no further Intermediate Point MUST discard the received message with no further
processing. processing.
The Intermediate Point MUST verify that the Address[Index] element The Intermediate Point MUST verify that the Address[Index] element
lists one of its unicast global or unique local IPv6 addresses (minus lists one of its unicast global or unique-local IPv6 addresses (minus
the prefix whose length in octets is specified in the Compr field), the prefix whose length in octets is specified in the Compr field),
failing which it MUST discard the Measurement Request with no further failing which it MUST discard the Measurement Request with no further
processing. The Intermediate Point MUST then increment the Index processing. The Intermediate Point MUST then increment the Index
field and use the Address[Index] element as the next hop (unless field and use the Address[Index] element as the next hop (unless the
Index value is now Num). If the Index value is now Num, the Index value is now Num). If the Index value is now Num, the
Intermediate Point MUST use the End Point Address as the next hop. Intermediate Point MUST use the End Point Address as the next hop.
The Intermediate Point MUST then complete the processing of the The Intermediate Point MUST then complete the processing of the
received Measurement Request as specified in Section 5.5. received Measurement Request as specified in Section 5.5.
5.5. Final Processing 5.5. Final Processing
The Intermediate Point MUST drop the received Measurement Request The Intermediate Point MUST drop the received Measurement Request
with no further processing: with no further processing:
o If the next hop address is not a unicast address; or o if the next-hop address is not a unicast address; or
o If the next hop is not on-link; or o if the next hop is not on-link; or
o If the next hop is not in the same RPL routing domain as the o if the next hop is not in the same RPL routing domain as the
Intermediate Point. Intermediate Point.
Next, the Intermediate Point MUST update the routing metric objects, Next, the Intermediate Point MUST update the routing metric objects,
inside the Metric Container option(s) inside the Measurement Request, inside the Metric Container option(s) inside the Measurement Request,
either by updating the aggregated value for the routing metric or by either by updating the aggregated value for the routing metric or by
attaching the local values for the metric inside the object. An attaching the local values for the metric inside the object. An
Intermediate Point can only update the existing metric objects and Intermediate Point can only update the existing metric objects and
MUST NOT add any new routing metric object to the Metric Container. MUST NOT add any new routing metric objects to the Metric Container.
An Intermediate Point MUST drop the Measurement Request with no An Intermediate Point MUST drop the Measurement Request with no
further processing if it cannot update a routing metric object further processing if it cannot update a routing metric object
specified inside the Metric Container. specified inside the Metric Container.
Finally, the Intermediate Point MUST unicast the Measurement Request Finally, the Intermediate Point MUST unicast the Measurement Request
to the next hop. to the next hop.
6. Processing a Measurement Request at the End Point 6. Processing a Measurement Request at the End Point
On receiving an MO, if a router chooses to process the message On receiving an MO, if a router chooses to process the message
further and finds one of its unicast global or unique local IPv6 further and finds one of its unicast global or unique-local IPv6
addresses (minus the prefix whose length in octets is specified in addresses (minus the prefix whose length in octets is specified in
the Compr field) listed as the End Point Address, the router the Compr field) listed as the End Point Address, the router
considers itself the End Point and MUST process the received MO in considers itself the End Point and MUST process the received MO in
the following manner. the following manner.
The End Point MUST discard the received message with no further The End Point MUST discard the received message with no further
processing if it is not a Measurement Request (i.e., T = 0). processing if it is not a Measurement Request (i.e., T = 0).
If the received Measurement Request traveled on a Hop-by-hop Route If the received Measurement Request traveled on a Hop-by-hop Route
with a local RPLInstanceID with route accumulation on (i.e., H = 1, with a local RPLInstanceID with route accumulation on (i.e., H = 1,
RPLInstanceID has a local value and A = 1), elements Address[0] RPLInstanceID has a local value, and A = 1), elements Address[0]
through Address[Index - 1] in the Address vector contain a complete through Address[Index - 1] in the Address vector contain a complete
Source Route from the Start Point to the End Point, which the End Source Route from the Start Point to the End Point, which the
Point MAY use, after reversal, to reach the Start Point. Note that End Point MAY use, after reversal, to reach the Start Point. Note
the Source Route in the Address vector does not include the Start that the Source Route in the Address vector does not include the
Point and the End Point addresses and the individual addresses do not Start Point and the End Point addresses, and that the individual
include the common prefix whose length in octets is specified in the addresses do not include the common prefix whose length in octets is
Compr field. specified in the Compr field.
If the received Measurement Request traveled on a Source Route and If the received Measurement Request traveled on a Source Route and
the Reverse flag is set to one (i.e., H = 0, R = 1), elements the Reverse flag is set to one (i.e., H = 0 and R = 1), elements
Address[0] through Address[Num - 1] in the Address vector contain a Address[0] through Address[Num - 1] in the Address vector contain a
complete Source Route from the Start Point to the End Point, which complete Source Route from the Start Point to the End Point, which
the End Point MAY use, after reversal, to reach the Start Point. the End Point MAY use, after reversal, to reach the Start Point.
Again, the Source Route in the Address vector does not include the Again, the Source Route in the Address vector does not include the
Start Point and the End Point addresses and the individual addresses Start Point and the End Point addresses, and the individual addresses
do not include the common prefix whose length in octets is specified do not include the common prefix whose length in octets is specified
in the Compr field. in the Compr field.
The End Point MUST update the routing metric objects in the Metric The End Point MUST update the routing metric objects in the Metric
Container options if required and MAY note the measured values for Container options if required and MAY note the measured values for
the complete route (especially, if the received Measurement Request the complete route (especially if the received Measurement Request is
is likely a response to an earlier Measurement Request that the End likely a response to an earlier Measurement Request that the
Point had sent to the Start Point with B flag set to one). End Point had sent to the Start Point with the B flag set to one).
The End Point MUST generate a Measurement Reply message as specified The End Point MUST generate a Measurement Reply message as specified
in Section 6.1. If the B flag is set to one in the received in Section 6.1. If the B flag is set to one in the received
Measurement Request, the End Point SHOULD generate a new Measurement Measurement Request, the End Point SHOULD generate a new Measurement
Request to measure the cost of its current (or the most preferred) Request to measure the cost of its current (or the most preferred)
route to the Start Point. The routing metrics used in the new route to the Start Point. The routing metrics used in the new
Measurement Request MUST include the routing metrics specified in the Measurement Request MUST include the routing metrics specified in the
received Measurement Request. received Measurement Request.
6.1. Generating the Measurement Reply 6.1. Generating the Measurement Reply
A Measurement Reply MUST have the Type (T) flag set to zero and need A Measurement Reply MUST have the Type (T) flag set to zero and need
not contain the Address vector. The following fields inside a not contain the Address vector. The following fields inside a
Measurement Reply MUST have the same values as they had inside the Measurement Reply MUST have the same values as they had inside the
corresponding Measurement Request: RPLInstanceID, Compr, SeqNo, Start corresponding Measurement Request: RPLInstanceID, Compr, SeqNo,
Point Address, End Point Address and Metric Container Option(s). The Start Point Address, End Point Address, and Metric Container
remaining fields inside a Measurement Reply may have any value and option(s). The remaining fields inside a Measurement Reply may have
MUST be ignored on reception at the Start Point; the received any value and MUST be ignored on reception at the Start Point; the
Measurement Request can, therefore, trivially be converted into a received Measurement Request can, therefore, trivially be converted
Measurement Reply by setting the Type (T) flag to zero. into a Measurement Reply by setting the Type (T) flag to zero.
A Measurement Reply MUST be unicast back to the Start Point: A Measurement Reply MUST be unicast back to the Start Point:
o If the Measurement Request traveled along a global DAG, identified o If the Measurement Request traveled along a global DAG, identified
by the RPLInstanceID field, the Measurement Reply MAY be unicast by the RPLInstanceID field, the Measurement Reply MAY be unicast
back to the Start Point along the same DAG. back to the Start Point along the same DAG.
o If the Measurement Request traveled along a Hop-by-hop Route with o If the Measurement Request traveled along a Hop-by-hop Route with
a local RPLInstanceID and accumulated a Source Route from the a local RPLInstanceID and accumulated a Source Route from the
Start Point to the End Point, this Source Route MAY be used after Start Point to the End Point, this Source Route MAY be used after
reversal to send the Measurement Reply back to the Start Point. reversal to send the Measurement Reply back to the Start Point.
o If the Measurement Request traveled along a Source Route and the R o If the Measurement Request traveled along a Source Route and the
flag inside the received message is set to one, the End Point MAY R flag inside the received message is set to one, the End Point
reverse the Source Route contained in the Address vector and use MAY reverse the Source Route contained in the Address vector and
it to send the Measurement Reply back to the Start Point. use it to send the Measurement Reply back to the Start Point.
7. Processing a Measurement Reply at the Start Point 7. Processing a Measurement Reply at the Start Point
When a router receives an MO, it examines if one of its unicast IPv6 When a router receives an MO, it examines the MO to see if one of its
addresses is listed as the Start Point Address. If yes, the router unicast IPv6 addresses is listed as the Start Point Address. If yes,
is the Start Point and MUST process the received message in the the router is the Start Point and MUST process the received message
following manner. in the following manner.
If the Start Point discovers that the received MO is not a If the Start Point discovers that the received MO is not a
Measurement Reply or if it no longer maintains state for the Measurement Reply, or if it no longer maintains state for the
corresponding Measurement Request, it MUST discard the received corresponding Measurement Request, it MUST discard the received
message with no further processing. message with no further processing.
The Start Point can use the routing metric objects inside the Metric The Start Point can use the routing metric objects inside the Metric
Container to evaluate the metrics for the measured P2P route. If a Container to evaluate the metrics for the measured P2P route. If a
routing metric object contains local metric values recorded by routing metric object contains local metric values recorded by
routers on the route, the Start Point can make use of these local routers on the route, the Start Point can make use of these local
values by aggregating them into an end-to-end metric according to the values by aggregating them into an end-to-end metric, according to
aggregation rules for the specific metric. A Start Point is then the aggregation rules for the specific metric. A Start Point is then
free to interpret the metrics for the route according to its local free to interpret the metrics for the route, according to its local
policy. policy.
8. Security Considerations 8. Security Considerations
In general, the security considerations for the route measurement In general, the security considerations for the route measurement
mechanism described in this document are similar to the ones for RPL mechanism described in this document are similar to those for RPL (as
(as described in Section 19 of [RFC6550]). Sections 6.1 and 10 of described in Section 19 of the RPL specification [RFC6550]).
RPL specification [RFC6550] describe RPL's security framework that Sections 6.1 and 10 of [RFC6550] describe RPL's security framework,
provides data confidentiality, authentication, replay protection and which provides data confidentiality, authentication, replay
delay protection services. This security framework is applicable to protection, and delay protection services. This security framework
the route measurement mechanism described here as well after taking is applicable to the route measurement mechanism described here as
in account the constraints specified in Section 3.2. well, after taking into account the constraints specified in
Section 3.2.
This document requires all routers participating in a secure This document requires that all routers participating in a secure
invocation of the route measurement process to use the Security invocation of the route measurement process use the Security
Configuration decided by the Start Point. The intention is to avoid Configuration chosen by the Start Point. The intention is to avoid
compromising the overall security of the route measurement due to compromising the overall security of the route measurement due to
some routers using a weaker Security Configuration. A router is some routers using a weaker Security Configuration. A router is
allowed to participate in a "secure" route measurement only if it can allowed to participate in a "secure" route measurement only if it can
support the Security Configuration in use, which also specifies the support the Security Configuration in use, which also specifies the
key in use. It does not matter whether the key is pre-installed or key in use. It does not matter whether the key is preinstalled or
dynamically acquired after proper authentication. The router must dynamically acquired after proper authentication. The router must
have the key in use before it can process or generate Secure MO have the key in use before it can process or generate Secure MO
messages. Hence, from the perspective of the route measurement messages. Hence, from the perspective of the route measurement
mechanism, there is no distinction between the "preinstalled" and mechanism, there is no distinction between the "preinstalled" and
"authenticated" security modes described in RPL specification "authenticated" security modes described in the RPL specification
[RFC6550]. Ofcourse if a compromised router has the key being used, [RFC6550]. Of course, if a compromised router has the key being
it could cause the route measurement to fail, or worse, insert wrong used, it could cause the route measurement to fail, or worse, insert
information in Secure MO messages. wrong information in Secure MO messages.
A rogue router acting as the Start Point could use the route A rogue router acting as the Start Point could use the route
measurement mechanism defined in this document to measure routes from measurement mechanism defined in this document to measure routes from
itself to other routers and thus find out key information about the itself to other routers and thus find out key information about the
LLN, e.g., the topological features of the LLN (such as the identity LLN, e.g., the topological features of the LLN (such as the identity
of the key routers in the topology) or the remaining energy levels of the key routers in the topology) or the remaining energy levels
[RFC6551] in the routers. This information can potentially be used [RFC6551] in the routers. This information can potentially be used
to attack the LLN. A rogue router could also use this mechanism to to attack the LLN. A rogue router could also use this mechanism to
send bogus Measurement Requests to arbitrary End Points. If send bogus Measurement Requests to arbitrary End Points. If
sufficient Measurement Requests are sent, then it may cause CPU sufficient Measurement Requests are sent, then it may cause CPU
overload in the routers in the network, drain their batteries and overload in the routers in the network, drain their batteries, and
cause traffic congestion in the network. Note that some of these cause traffic congestion in the network. Note that some of these
problems would occur even if the compromised router were to generate problems would occur even if the compromised router were to generate
bogus data traffic to arbitrary destinations. bogus data traffic to arbitrary destinations.
To protect against such misuse, this document allows RPL routers To protect against such misuse, this document allows RPL routers
implementing this mechanism to not process MO messages (or process implementing this mechanism to not process MO messages (or process
such messages selectively) based on a local policy. For example, an such messages selectively), based on a local policy. For example, an
LLN deployment might require the use of Secure MO messages generated LLN deployment might require the use of Secure MO messages generated
using a key that could be obtained only after proper authentication. using a key that could be obtained only after proper authentication.
Note that this document requires an LLN deployment to support Secure Note that this document requires that an LLN deployment support
MO messages so that such policies can be enforced where considered Secure MO messages so that such policies can be enforced where
essential. considered essential.
Since a Measurement Request can travel along a Source Route specified Since a Measurement Request can travel along a Source Route specified
in the Address vector, some of the security concerns that led to the in the Address vector, some of the security concerns that led to the
deprecation of Type 0 routing header [RFC5095] may be valid here. To deprecation of Type 0 routing headers [RFC5095] may be valid here.
address such concerns, the mechanism described in this document To address such concerns, the mechanism described in this document
includes several remedies: includes several remedies, in the form of the following requirements:
o This document requires that a route inserted inside the Address o A route inserted inside the Address vector must be a strict Source
vector must be a strict Source Route and must not include any Route and must not include any multicast addresses.
multicast addresses.
o This document requires that an MO message must not cross the o An MO message must not cross the boundaries of the RPL routing
boundaries of the RPL routing domain where it originated. A domain where it originated. A router must not forward a received
router must not forward a received MO message further if the next MO message further if the next hop belongs to a different RPL
hop belongs to a different RPL routing domain. Hence, any routing domain. Hence, any security problems associated with the
security problems associated with the mechanism would be limited mechanism would be limited to one RPL routing domain.
to one RPL routing domain.
o This document requires that a router must drop a received o A router must drop a received Measurement Request if the next-hop
Measurement Request if the next hop address is not on-link or if address is not on-link or if it is not a unicast address.
it is not a unicast address.
9. IANA Considerations 9. IANA Considerations
This document defines two new RPL messages: This document defines two new RPL messages:
o "Measurement Object" (see Section 3.1), assigned a value TBD1 from o "Measurement Object" (see Section 3.1), assigned a value of 0x06
the "RPL Control Codes" space [to be removed upon publication: from the "RPL Control Codes" space [RFC6550].
http://www.iana.org/assignments/rpl/rpl.xml#control-codes]
[RFC6550]. IANA is requested to allocate TBD1 from the range
0x00-0x7F to indicate a message without security enabled. The
string TBD1 in this document should be replaced by the allocated
value. These last two sentences should be removed before
publication.
o "Secure Measurement Object" (see Section 3.2), assigned a value o "Secure Measurement Object" (see Section 3.2), assigned a value of
TBD2 from the "RPL Control Codes" space [to be removed upon 0x86 from the "RPL Control Codes" space [RFC6550].
publication:
http://www.iana.org/assignments/rpl/rpl.xml#control-codes]
[RFC6550]. IANA is requested to allocate TBD2 from the range
0x80-0xFF to indicate a message with security enabled. The string
TBD2 in this document should be replaced by the allocated value.
These last two sentences should be removed before publication.
+------+---------------------------+---------------+ +------+---------------------------+---------------+
| Code | Description | Reference | | Code | Description | Reference |
+------+---------------------------+---------------+ +------+---------------------------+---------------+
| TBD1 | Measurement Object | This document | | 0x06 | Measurement Object | This document |
| TBD2 | Secure Measurement Object | This document | | 0x86 | Secure Measurement Object | This document |
+------+---------------------------+---------------+ +------+---------------------------+---------------+
RPL Control Codes RPL Control Codes
10. Acknowledgements 10. Acknowledgements
Authors gratefully acknowledge the contributions of Ralph Droms, The authors gratefully acknowledge the contributions of Ralph Droms,
Adrian Farrel, Joel Halpern, Matthias Philipp, Pascal Thubert, Adrian Farrel, Joel Halpern, Matthias Philipp, Pascal Thubert,
Richard Kelsey and Zach Shelby in the development of this document. Richard Kelsey, and Zach Shelby in the development of this document.
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-roll-p2p-rpl]
Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J.
Martocci, "Reactive Discovery of Point-to-Point Routes in
Low Power and Lossy Networks", draft-ietf-roll-p2p-rpl-17
(work in progress), March 2013.
[I-D.ietf-roll-terminology]
Vasseur, J., "Terminology in Low power And Lossy
Networks", draft-ietf-roll-terminology-12 (work in
progress), March 2013.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006. Version 6 (IPv6) Specification", RFC 4443, March 2006.
[RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R.,
Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Levis, P., Pister, K., Struik, R., Vasseur, JP., and R.
Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Alexander, "RPL: IPv6 Routing Protocol for Low-Power and
Lossy Networks", RFC 6550, March 2012. Lossy Networks", RFC 6550, March 2012.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554,
March 2012.
[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
J. Martocci, "Reactive Discovery of Point-to-Point Routes
in Low-Power and Lossy Networks", RFC 6997, August 2013.
11.2. Informative References 11.2. Informative References
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095, of Type 0 Routing Headers in IPv6", RFC 5095,
December 2007. December 2007.
[RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation
Routing Requirements in Low-Power and Lossy Networks", Routing Requirements in Low-Power and Lossy Networks",
RFC 5826, April 2010. RFC 5826, April 2010.
[RFC5867] Martocci, J., De Mil, P., Riou, N., and W. Vermeylen, [RFC5867] Martocci, J., De Mil, P., Riou, N., and W. Vermeylen,
"Building Automation Routing Requirements in Low-Power and "Building Automation Routing Requirements in Low-Power and
Lossy Networks", RFC 5867, June 2010. Lossy Networks", RFC 5867, June 2010.
[RFC6551] Vasseur, JP., Kim, M., Pister, K., Dejean, N., and D. [RFC6551] Vasseur, JP., Kim, M., Pister, K., Dejean, N., and D.
Barthel, "Routing Metrics Used for Path Calculation in Barthel, "Routing Metrics Used for Path Calculation in
Low-Power and Lossy Networks", RFC 6551, March 2012. Low-Power and Lossy Networks", RFC 6551, March 2012.
[ROLL-TERMS]
Vasseur, JP., "Terminology in Low power And Lossy
Networks", Work in Progress, March 2013.
Authors' Addresses Authors' Addresses
Mukul Goyal (editor) Mukul Goyal (editor)
University of Wisconsin Milwaukee University of Wisconsin Milwaukee
3200 N Cramer St 3200 N. Cramer St.
Milwaukee, WI 53211 Milwaukee, WI 53201
USA USA
Phone: +1 414 2295001 Phone: +1-414-229-5001
Email: mukul@uwm.edu EMail: mukul@uwm.edu
Emmanuel Baccelli Emmanuel Baccelli
INRIA INRIA
Phone: +33-169-335-511 Phone: +33-169-335-511
Email: Emmanuel.Baccelli@inria.fr EMail: Emmanuel.Baccelli@inria.fr
URI: http://www.emmanuelbaccelli.org/ URI: http://www.emmanuelbaccelli.org/
Anders Brandt Anders Brandt
Sigma Designs Sigma Designs
Emdrupvej 26A, 1. Emdrupvej 26A, 1.
Copenhagen, Dk-2100 Copenhagen, Dk-2100
Denmark Denmark
Phone: +45 29609501 Phone: +45-29609501
Email: abr@sdesigns.dk EMail: abr@sdesigns.dk
Jerald Martocci Jerald Martocci
Johnson Controls Johnson Controls
507 E Michigan Street 507 E. Michigan Street
Milwaukee 53202 Milwaukee, WI 53202
USA USA
Phone: +1 414 524 4010 Phone: +1-414-524-4010
Email: jerald.p.martocci@jci.com EMail: jerald.p.martocci@jci.com
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