draft-ietf-roll-p2p-measurement-03.txt   draft-ietf-roll-p2p-measurement-04.txt 
Internet Engineering Task Force M. Goyal, Ed. Internet Engineering Task Force M. Goyal, Ed.
Internet-Draft University of Wisconsin Internet-Draft University of Wisconsin
Intended status: Experimental Milwaukee Intended status: Experimental Milwaukee
Expires: September 5, 2012 E. Baccelli Expires: September 8, 2012 E. Baccelli
INRIA INRIA
A. Brandt A. Brandt
Sigma Designs Sigma Designs
J. Martocci J. Martocci
Johnson Controls Johnson Controls
March 4, 2012 March 7, 2012
A Mechanism to Measure the Quality of a Point-to-point Route in a Low A Mechanism to Measure the Quality of a Point-to-point Route in a Low
Power and Lossy Network Power and Lossy Network
draft-ietf-roll-p2p-measurement-03 draft-ietf-roll-p2p-measurement-04
Abstract Abstract
This document specifies a mechanism that enables an RPL router to This document specifies a mechanism that enables an RPL router to
measure the quality of an existing route towards another RPL router measure the quality of an existing route towards another RPL router
in a low power and lossy network, thereby allowing the router to in a low power and lossy network, thereby allowing the router to
decide if it wants to initiate the discovery of a better route. decide if it wants to initiate the discovery of a better route.
Status of this Memo Status of this Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 5, 2012. This Internet-Draft will expire on September 8, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.2. Secure MO . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2. Secure MO . . . . . . . . . . . . . . . . . . . . . . . . 9
4. Originating a Measurement Request . . . . . . . . . . . . . . 9 4. Originating a Measurement Request . . . . . . . . . . . . . . 9
4.1. To Measure A Hop-by-hop Route with a Global 4.1. To Measure A Hop-by-hop Route with a Global
RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10 RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10
4.2. To Measure A Hop-by-hop Route with a Local 4.2. To Measure A Hop-by-hop Route with a Local
RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10 RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10
4.3. To Measure A Source Route . . . . . . . . . . . . . . . . 11 4.3. To Measure A Source Route . . . . . . . . . . . . . . . . 11
5. Processing a Measurement Request at an Intermediate Router . . 12 5. Processing a Measurement Request at an Intermediate Router . . 12
5.1. Determining Next Hop For An MO Measuring A Source Route . 13 5.1. Determining Next Hop For An MO Measuring A Source Route . 13
5.2. Determining Next Hop For An MO Measuring A Hop-by-hop 5.2. Determining Next Hop For An MO Measuring A Hop-by-hop
Route . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Route . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6. Processing a Measurement Request at the Target . . . . . . . . 14 6. Processing a Measurement Request at the Target . . . . . . . . 15
7. Processing a Measurement Reply at the Origin . . . . . . . . . 15 7. Processing a Measurement Reply at the Origin . . . . . . . . . 16
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
11.1. Normative References . . . . . . . . . . . . . . . . . . . 17 11.1. Normative References . . . . . . . . . . . . . . . . . . . 18
11.2. Informative References . . . . . . . . . . . . . . . . . . 17 11.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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 Low
power and Lossy Network (LLN) is a key requirement for many power and Lossy Network (LLN) is a key requirement for many
applications [RFC5826][RFC5867]. RPL [I-D.ietf-roll-rpl], the IPv6 applications [RFC5826][RFC5867]. RPL [I-D.ietf-roll-rpl], the IPv6
Routing Protocol for LLNs, constrains the LLN topology to a Directed Routing Protocol for LLNs, constrains the LLN topology to a Directed
Acyclic Graph (DAG) built to optimize the routing costs to reach the Acyclic Graph (DAG) built to optimize the routing costs to reach the
DAG's root. The P2P routing functionality, available under RPL, has DAG's root. The P2P routing functionality, available under RPL, has
the following key limitations: the following key limitations:
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. 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: The origin sets this field to indicate the o RPLInstanceID: This field is relevant only if a hop-by-hop route
RPLInstanceID of the route being measured. An intermediate router is being measured, i.e., the H flag, described subsequently, is
MUST discard the received MO message if it is not aware of the RPL set to one. In this case, the origin MUST set this field to the
Instance specified by the RPLInstanceID value. If the RPLInstanceID of the hop-by-hop route being measured. If a source
RPLInstanceID is a local value, the RPL Instance is identified by route is being measured, the origin MUST set this field to binary
both the RPLInstanceID and the Origin Address fields. An value 10000000. An intermediate router MUST set the RPLInstanceID
intermediate router MUST set the RPLInstanceID field in the field in the outgoing MO packet to the same value that it had in
outgoing MO packet to the same value that it had in the the corresponding incoming MO packet unless it is the root of a
corresponding incoming MO packet. non-storing global DAG, identified by the RPLInstanceID, along
which the MO packet had been traveling so far and the router
intends to insert a source route inside the Address vector to
direct it towards the target. In that case, the router MUST set
the RPLInstanceID field in the outgoing MO packet to binary value
10000000.
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 Origin/Target Address fields when specifying IPv6 addresses in the Origin/Target Address fields
and the Address vector. The "Compr" field, a 4-bit unsigned and the Address vector. The "Compr" field, a 4-bit unsigned
integer, is set by the origin to specify the number of prefix integer, is set by the origin to specify the number of prefix
octets that are elided from the IPv6 addresses in Origin/Target octets that are elided from the IPv6 addresses in Origin/Target
Address fields and the Address vector. An intermediate router Address fields and the Address vector. An intermediate router
MUST set the Compr field in the outgoing MO packet to the same MUST set the Compr field in the outgoing MO packet to the same
value that it had in the corresponding incoming MO packet. The value that it had in the corresponding incoming MO packet. The
Compr value will be 0 if full IPv6 addresses are carried in the intermediate router MUST drop the received MO message if the Compr
Origin/Target Address fields and the Address vector. value specified in the message does not match what the router
considers the length of the common prefix to be. The origin will
set the Compr value to zero if full IPv6 addresses are to be
carried in the Origin Address/Target Address fields and the
Address vector.
o Type (T): This flag is set to 1 if the MO represents a Measurement o Type (T): This flag is set to one if the MO represents a
Request. The flag is cleared to 0 if the MO is a Measurement Measurement Request. The flag is set to zero if the MO is a
Reply. Measurement Reply.
o Hop-by-hop (H): The origin sets this flag to 1 if the route being o Hop-by-hop (H): The origin MUST set this flag to one if the route
measured is a hop-by-hop route. In that case, the hop-by-hop being measured is a hop-by-hop route. In that case, the hop-by-
route is identified by the RPLInstanceID and, if the RPLInstanceID hop route is identified by the RPLInstanceID and, if the
is a local value, the Origin Address serving as the DODAGID. The RPLInstanceID is a local value, the Origin Address and Target
origin resets this flag to 0 if the route being measured is a Address fields inside the message. The origin MUST set this flag
source route specified in the Address vector. An intermediate to zero if the route being measured is a source route specified in
router MUST set the H flag in an outgoing MO packet to the same the Address vector. An intermediate router MUST set the H flag in
value that it had in the corresponding incoming MO packet unless an outgoing MO packet to the same value that it had in the
the router is the root of the non-storing global DAG, identified corresponding incoming MO packet unless the router is the root of
by the RPLInstanceID, along which the MO packet had been traveling the non-storing global DAG, identified by the RPLInstanceID, along
so far. In that case, the DAG root MUST reset the H flag to 0 in which the MO packet had been traveling so far and the router
the outgoing MO packet if it intends to insert a source route in intends to insert a source route inside the Address vector to
the Address vector to direct the MO packet towards the target. direct it towards the target. In that case, the router MUST reset
the H flag to zero in the outgoing MO packet.
o Accumulate Route (A): This flag is relevant only if the MO o Accumulate Route (A): This flag is relevant only if the MO
represents a Measurement Request that travels along a hop-by-hop represents a Measurement Request that travels along a hop-by-hop
route represented by a local RPLInstanceID. In other words, this route represented by a local RPLInstanceID. In other words, this
flag MAY be set to 1 only if T = 1, H = 1 and the RPLInstanceID flag MAY be set to one only if T = 1, H = 1 and the RPLInstanceID
field has a local value. Otherwise, this flag MUST be cleared to field has a local value. Otherwise, this flag MUST be set to
0. A value 1 in this flag indicates that the Measurement Request zero. A value 1 in this flag indicates that the Measurement
MUST accumulate a source route for use by the target to send the Request MUST accumulate a source route for use by the target to
Measurement Reply back to the origin. In this case, an send the Measurement Reply back to the origin. In this case, an
intermediate router MUST add its unicast IPv6 address (after intermediate router MUST add its unicast IPv6 address (after
eliding Compr number of prefix octets) to the Address vector in eliding Compr number of prefix octets) to the Address vector in
the manner specified later. Route accumulation is not allowed the manner specified later. Route accumulation is not allowed
when the Measurement Request travels along a hop-by-hop route with when the Measurement Request travels along a hop-by-hop route with
a global RPLInstanceID, i.e., along a global DAG, because: a global 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 target; and route to the target; and
* The target can presumably reach the origin along this global * The target can presumably reach the origin along this global
DAG. DAG.
o Reverse (R): This flag is relevant only if the MO represents a o Reverse (R): This flag is relevant only if the MO represents a
Measurement Request that travels along a source route, specified Measurement Request that travels along a source route, specified
in the Address vector, to the target. In other words, this flag in the Address vector, to the target. In other words, this flag
MAY be set to 1 only if T = 1 and H = 0. Otherwise, this flag MAY be set to one only if T = 1 and H = 0. Otherwise, this flag
MUST be cleared to 0. A value 1 in the flag indicates that the MUST be set to zero. A value 1 in the flag indicates that the
Address vector contains a complete source route from the origin to Address vector contains a complete source route from the origin to
the target, which can be used, after reversal, by the target to the target, which can be used, after reversal, by the target to
source route the Measurement Reply message back to the origin. source route the Measurement Reply message back to the origin.
o Back Request (B): This flag serves as a request to the target to o Back Request (B): This flag serves as a request to the target to
send a Measurement Request towards the origin. The origin MAY set send a Measurement Request towards the origin. The origin MAY set
this flag to 1 if it wants to make such a request to the target. this flag to one to make such a request to the target. An
An intermediate router MUST set the B flag in an outgoing MO intermediate router MUST set the B flag in an outgoing MO packet
packet to the same value that it had in the corresponding incoming to the same value that it had in the corresponding incoming MO
MO packet. On receiving a Measurement Request with the B flag set packet. On receiving a Measurement Request with the B flag set to
to 1, the target SHOULD generate a Measurement Request to measure one, the target SHOULD generate a Measurement Request to measure
the cost of its current (or the most preferred) route to the the cost of its current (or the most preferred) route to the
origin. Receipt of this Measurement Request would allow the origin. Receipt of this Measurement Request would allow the
origin to know the cost of the back route from the target to origin to know the cost of the back route from the target to
itself and thus determine the round-trip cost of reaching the itself and thus determine the round-trip cost of reaching the
target. target.
o Intermediate Reply (I): Relevant only if a hop-by-hop route is o Intermediate Reply (I): Relevant only if a hop-by-hop route is
being measured, this flag serves as a permission to an being measured, this flag serves as a permission to an
intermediate router to generate a Measurement Reply if it knows intermediate router to generate a Measurement Reply if it knows
the cost of the rest of the route being measured. The origin MAY the cost of the rest of the route being measured. The origin MAY
set this flag to 1 if a hop-by-hop route is being measured (i.e., set this flag to one if a hop-by-hop route is being measured
H = 1) and the origin wants to allow an intermediate router to (i.e., H = 1) and the origin wants to allow an intermediate router
generate the Measurement Reply in response to this Measurement to generate the Measurement Reply in response to this Measurement
Request. Setting this flag may be useful in scenarios where the Request. Setting this flag to one may be useful in scenarios
Hop Count [I-D.ietf-roll-routing-metrics] is the routing metric of where the Hop Count [I-D.ietf-roll-routing-metrics] is the routing
interest and the origin expects an intermediate router (e.g. the metric of interest and the origin expects an intermediate router
root of a non-storing DAG or a common ancestor of the origin and (e.g. the root of a non-storing DAG or a common ancestor of the
the target in a storing DAG) to know the Hop Count of the origin and the target in a storing DAG) to know the Hop Count of
remainder of the route to the target. This flag MUST be cleared the remainder of the route to the target. This flag MUST be set
to 0 if the route being measured is a source route (i.e., H = 0). to zero if the route being measured is a source route (i.e., H =
0).
o SequenceNo: A 6-bit sequence number, assigned by the origin, that o SequenceNo: A 6-bit sequence number, assigned by the origin, that
allows the origin to uniquely identify a Measurement Request and allows the origin to uniquely identify a Measurement Request and
the corresponding Measurement Reply. An intermediate router MUST the corresponding Measurement Reply. An intermediate router MUST
set this field in the outgoing MO packet to the same value that it set this field in the outgoing MO packet to the same value that it
had in the corresponding incoming MO packet. The target MUST set had in the corresponding incoming MO packet. The target MUST set
this field in a Measurement Reply message to the same value that this field in a Measurement Reply message to the same value that
it had in the corresponding Measurement Request message. it had in the corresponding Measurement Request message.
o Num: The origin sets this field to indicate the number of fields o Num: This field indicates the number of elements, each (16 -
in the Address vector. If the value of this field is zero, the Compr) octets in size, inside the Address vector. If the value of
Address vector is not present in the MO. 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 (T=1,H=0), this field route contained in the Address vector (T=1,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 A flag is set route with a local RPLInstanceID and the A flag is set
(T=1,H=1,A=1 and RPLInstanceID field has a local value), this (T=1,H=1,A=1 and RPLInstanceID field has a local value), this
field indicates the index in the Address vector where an field indicates the index in the Address vector where an
intermediate router receiving the MO message must store its IPv6 intermediate router receiving the MO message must store its IPv6
address. Otherwise, this field MUST be set to zero on address. Otherwise, this field MUST be set to zero on
transmission and ignored on reception. transmission and ignored on reception.
o Origin Address: A unicast IPv6 address of the origin after eliding o Origin Address: A unicast IPv6 address of the origin after eliding
Compr number of prefix octets. If the MO is traveling along a Compr number of prefix octets. If the MO is traveling along a
hop-by-hop route and the RPLInstanceID field indicates a local hop-by-hop route and the RPLInstanceID field indicates a local
value, the Origin Address field MUST specify the DODAGID value value, the Origin Address field MUST specify the DODAGID value
that, along with the RPLInstanceID, uniquely identifies the hop- that, along with the RPLInstanceID and the Target Address,
by-hop route being measured. uniquely identifies the hop-by-hop route being measured.
o Target Address: A unicast IPv6 address of the target after eliding o Target Address: A unicast IPv6 address of the target after eliding
Compr number of prefix octets. Compr number of prefix octets.
o Address[1..Num]: A vector of unicast IPv6 addresses (with Compr o Address[1..Num]: A vector of unicast IPv6 addresses (with Compr
number of prefix octets elided) representing a source route to the number of prefix octets elided) representing a source route to the
target: target:
* Each element in the vector has size (16 - Compr) octets. * Each element in the vector has size (16 - Compr) octets.
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by the Num field. by the Num field.
* When the Measurement Request is traveling along a hop-by-hop * When the Measurement Request is traveling along a hop-by-hop
route with local RPLInstanceID and has the A flag set, the route with local RPLInstanceID and has the A flag set, the
Address vector is used to accumulate a source route to be used Address vector is used to accumulate a source route to be used
by the target to send the Measurement Reply back to the origin. by the target to send the Measurement Reply back to the origin.
In this case, the route MUST be accumulated in the forward In this case, the route MUST be accumulated in the forward
direction, i.e., from the origin to the target. The target direction, i.e., from the origin to the target. The target
router would reverse this route to obtain a source route from router would reverse this route to obtain a source route from
itself to the origin. The IPv6 addresses in the accumulated itself to the origin. The IPv6 addresses in the accumulated
route MUST be accessible in the backward direction, i.e., from route MUST be reachable in the backward direction, i.e., from
the target to the origin. An intermediate router adding its the target to the origin. An intermediate router adding its
address to the Address vector MUST ensure that its address does address to the Address vector MUST ensure that its address does
not already exist in the vector. not already exist in the vector.
* When the Measurement Request is traveling along a source route, * When the Measurement Request is traveling along a source route,
the Address vector MUST contain a complete route to the target the Address vector MUST contain a complete route to the target
and the IPv6 addresses in the Address vector MUST be accessible and the IPv6 addresses in the Address vector MUST be reachable
in the forward direction, i.e., from the origin to the target. in the forward direction, i.e., from the origin to the target.
A router (origin or an intermediate router) inserting an A router (origin or an intermediate router) inserting an
Address vector inside an MO MUST ensure that no address appears Address vector inside an MO MUST ensure that no address appears
more than once inside the vector. Each router on the way MUST more than once inside the vector. Each router on the way MUST
ensure that the loops do not exist within the source route. ensure that the loops do not exist within the source route.
The origin MAY set the R flag in the MO if the route in the The origin MAY set the R flag in the MO if the route in the
Address vector represents a complete route from the origin to Address vector represents a complete route from the origin to
the target and this route can be used after reversal by the the target and this route can be used after reversal by the
target to send the Measurement Reply message back to the target to send the Measurement Reply message back to the origin
origin. (i.e., the IPv6 addresses in the Address vector are reachable
in the backward direction - from the target to the origin).
* The origin and target addresses MUST NOT be included in the * The origin and target addresses MUST NOT be included in the
Address vector. Address vector.
* The Address vector MUST NOT contain any multicast addresses. * The Address vector MUST NOT contain any multicast addresses.
o Metric Container Options: An MO MUST contain one or more Metric o Metric Container Options: An MO MUST contain one or more Metric
Container options to accumulate the routing metric values for the Container options to accumulate the routing metric values for the
route being measured. route being measured.
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A Secure MO message follows the format in Figure 7 of A Secure MO message follows the format in Figure 7 of
[I-D.ietf-roll-rpl], where the base format is the base MO shown in [I-D.ietf-roll-rpl], where the base format is the base MO shown in
Figure 1. Figure 1.
4. Originating a Measurement Request 4. Originating a Measurement Request
If an origin needs to measure the routing metric values along a P2P If an origin needs to measure the routing metric values along a P2P
route towards a target, it generates an MO message and sets its route towards a target, it generates an MO message and sets its
fields as described in Section 3.1. The setting of MO fields in fields as described in Section 3.1. The setting of MO fields in
specific cases is described below. In all cases, the origin MUST set specific cases is described below. In all cases, the origin MUST set
the T flag to 1 to indicate that the MO represents a Measurement the T flag to one to indicate that the MO represents a Measurement
Request. The origin MUST also include one or more Metric Container Request. The origin MUST also include one or more Metric Container
options inside the MO to carry the routing metric objects of options inside the MO to carry the routing metric objects of
interest. Depending on the metrics being measured, the origin must interest. Depending on the metrics being measured, the origin must
also initiate these routing metric objects by including the values of also initiate these routing metric objects by including the values of
the routing metrics for the first hop on the P2P route being the routing metrics for the first hop on the P2P route being
measured. measured.
After setting the MO fields appropriately, the origin MUST unicast After setting the MO fields appropriately, the origin determines the
the MO message to the next hop on the P2P route. next hop on the P2P route being measured. If a hop-by-hop route is
being measured (i.e., the H flag is set to one), the next hop is
determined using the RPLInstanceID, the Target Address and, if
RPLInstanceID is a local value, the Origin Address fields in the MO.
If a source route is being measured (i.e., the H flag is set to
zero), the Address[1] element contains the next hop address.
The origin MUST discard the MO message if:
o the next hop address is not a unicast address; or
o the next hop is not on-link; or
o the next hop is not in the same RPL routing domain as the origin.
Otherwise, the origin MUST unicast the MO message to the next hop on
the P2P route.
4.1. To Measure A Hop-by-hop Route with a Global RPLInstanceID 4.1. To Measure 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,
the MO message MUST NOT contain the Address vector and the following the MO message MUST NOT contain the Address vector and the following
MO fields MUST be set in the manner specified below: MO fields MUST be set in the manner specified below:
o Hop-by-hop (H): This flag MUST be set to 1. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be cleared to 0. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag MUST be cleared to 0. o Reverse (R): This flag MUST be set to zero.
o Num: This field MUST be cleared to 0. o Num: This field MUST be set to zero.
o Index: This field MUST be cleared to 0. o Index: This field MUST be set to zero.
4.2. To Measure A Hop-by-hop Route with a Local RPLInstanceID 4.2. To Measure A Hop-by-hop Route with a Local RPLInstanceID
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 MO is not accumulating a source route for the target's use, and the MO is not accumulating a source route for the target's use,
the MO message MUST NOT contain the Address vector and the following the MO message MUST NOT contain the Address vector and the following
MO fields MUST be set in the manner specified below: MO fields MUST be set in the manner specified below:
o Hop-by-hop (H): This flag MUST be set to 1. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be cleared to 0. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag MUST be cleared to 0. o Reverse (R): This flag MUST be set to zero.
o Num: This field MUST be cleared to 0. o Num: This field MUST be set to zero.
o Index: This field MUST be cleared to 0. o Index: This field MUST be set to zero.
o Origin Address: This field MUST contain the DODAGID value (after o Origin Address: This field MUST contain the DODAGID value (after
eliding Compr number of prefix octets) associated with the route eliding Compr number of prefix octets) associated with the route
being measured. being measured.
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 origin desires the MO to accumulate a source route for the and the origin desires the MO to accumulate a source route for the
target to send the Measurement Reply message back, it MUST set the target to send the Measurement Reply message back, it MUST set the
following MO fields in the manner specified below: following MO fields in the manner specified below:
o Hop-by-hop (H): This flag MUST be set to 1. o Hop-by-hop (H): This flag MUST be set to one.
o Accumulate Route (A): This flag MUST be set to 1. o Accumulate Route (A): This flag MUST be set to one.
o Reverse (R): This flag MUST be cleared to 0. o Reverse (R): This flag MUST be set to zero.
o Intermediate Reply (I): This flag MUST be cleared to 0. o Intermediate Reply (I): This flag MUST be set to zero.
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 origin to the target. accomodate a complete source route from the origin to the target.
All the bits in the Address vector field MUST be cleared to 0. All the bits in the Address vector field MUST be set to zero.
o Num: This field MUST specify the number of address elements that o Num: This field MUST specify the number of address elements that
can fit inside the Address vector. can fit inside the Address vector.
o Index: This field MUST be set to 1. o Index: This field MUST be set to one.
o Origin Address: This field MUST contain the DODAGID value (after o Origin Address: This field MUST contain the DODAGID value (after
eliding Compr number of prefix octets) associated with the route eliding Compr number of prefix octets) associated with the route
being measured. being measured.
4.3. To Measure A Source Route 4.3. To Measure A Source Route
If a source route is being measured, the origin MUST set the If a source route is being measured, the origin MUST set the
following MO fields in the manner specified below: following MO fields in the manner specified below:
o Hop-by-hop (H): This flag MUST be cleared to 0. o Hop-by-hop (H): This flag MUST be set to zero.
o Accumulate Route (A): This flag MUST be cleared to 0. o Accumulate Route (A): This flag MUST be set to zero.
o Reverse (R): This flag SHOULD be set to 1 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 target to the Address vector can be reversed and used by the target to
source route the Measurement Reply message back to the origin. source route the Measurement Reply message back to the origin.
Otherwise, this flag MUST be cleared to 0. Otherwise, this flag MUST be set to zero.
o Intermediate Reply (I): This flag MUST be cleared to 0. o Intermediate Reply (I): This flag MUST be set to zero.
o Address vector: o Address vector:
* The Address vector MUST contain a complete route from the * The Address vector MUST contain a complete route from the
origin to the target (excluding the origin and the target). origin to the target (excluding the origin and the target).
* The IPv6 addresses (with Compr prefix octets elided) in the * The IPv6 addresses (with Compr prefix octets elided) in the
Address vector MUST be accessible in the forward direction, Address vector MUST be reachable in the forward direction,
i.e., from the origin to the target. i.e., from the origin to the target.
* If the R flag is set to one, the IPv6 addresses (with Compr
prefix octets elided) in the Address vector MUST also be
reachable in the backward direction, i.e., from the target to
the origin.
* To prevent loops in the source route, the origin MUST ensure * To prevent loops in the source route, the origin MUST ensure
compliance to the following rules: compliance to the following rules:
+ Any IPv6 address MUST NOT appear more than once in the + Any IPv6 address MUST NOT appear more than once in the
Address vector. Address vector.
+ If the Address vector includes multiple IPv6 addresses + If the Address vector includes multiple IPv6 addresses
assigned to the origin's interfaces, such addresses MUST assigned to the origin's interfaces, such addresses MUST
appear back to back inside the Address vector. appear back to back inside the Address vector.
* Each address appearing in the Address vector MUST be a unicast * Each address appearing in the Address vector MUST be a unicast
address. address.
o Num: This field MUST be set to indicate the number of elements in o Num: This field MUST be set to indicate the number of elements in
the Address vector. the Address vector.
o Index: This field MUST be set to 1. o Index: This field MUST be set to one.
The origin MUST NOT send the packet further if the next hop address
on the source route is not on-link.
5. Processing a Measurement Request at an Intermediate Router 5. Processing a Measurement Request at an Intermediate Router
A router (an intermediate router or the target) MAY discard a A router (an intermediate router or the target) MAY discard a
received MO with no further processing to meet any policy-related received MO with no processing to meet any policy-related goal. Such
goal. Such policy goals may include the need to reduce the router's policy goals may include the need to reduce the router's CPU load or
CPU load or to enhance its battery life. to enhance its battery life.
A router MUST discard a received MO with no further processing:
o If the router is not aware of the RPL Instance identified by the
RPLInstanceID (and the Origin Address, if RPLInstanceID is a local
value) field in the message.
o If the Compr field is not same as what the router considers as the A router MUST discard a received MO with no further processing if the
length of the common prefix used in IPv6 addresses in the LLN. Compr field inside the received message is not same as what the
router considers the length of the common prefix used in IPv6
addresses in the LLN to be.
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 check if one of its IPv6 addresses is listed as
either the Origin or the Target Address. If neither, the router either the Origin or the Target Address. If neither, the router
considers itself an Intermediate Router and MUST process the received considers itself an Intermediate Router and MUST process the received
MO in the following manner. MO in the following manner.
An intermediate router MUST discard the packet with no further An intermediate router MUST discard the packet with no further
processing if the received MO is not a Measurement Request. processing if the received MO is not a Measurement Request.
If the I flag is set to 1 in the received MO and the intermediate If the H and I flags are set to one in the received MO and the
router knows the values of the routing metrics, specified in the intermediate router knows the values of the routing metrics,
Metric Container, for the remainder of the route, it MAY generate a specified in the Metric Container, for the remainder of the route, it
Measurement Reply on the target's behalf in the manner specified in MAY generate a Measurement Reply on the target's behalf in the manner
Section 6 (after including in the Measurement Reply the relevant specified in Section 6 (after including in the Measurement Reply the
routing metric values for the complete route being measured). relevant routing metric values for the complete route being
Otherwise, the intermediate router MUST process the received MO in measured). Otherwise, the intermediate router MUST process the
the following manner. received MO in the following manner.
The router MUST determine the next hop on the P2P route being The router MUST determine the next hop on the P2P route being
measured in the manner described below. The router MUST drop the MO measured in the manner described below. The router MUST drop the MO
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 message to Unreachable (with Code 0 - No Route To Destination) error message to
the source of the message if it can not determine the next hop for the source of the message if it can not determine the next hop for
the message. the message. The router MUST drop the MO with no further processing:
After determining the next hop, the router MUST update the routing o If the next hop address is not a unicast address; or
metric objects, contained in the Metric Container options inside the
MO, either by updating the aggregated value for the routing metric or o If the next hop is not on-link; or
by attaching the local values for the metric inside the object.
After updating the routing metrics, the router MUST unicast the MO to o If the next hop is not in the same RPL routing domain as the
the next hop. router.
Next, the router MUST update the routing metric objects, contained in
the Metric Container options inside the MO, either by updating the
aggregated value for the routing metric or by attaching the local
values for the metric inside the object. After updating the routing
metrics, the router MUST unicast the MO to the next hop.
5.1. Determining Next Hop For An MO Measuring A Source Route 5.1. Determining Next Hop For An MO Measuring A Source Route
In case the received MO is measuring a source route (H=0), In case the received MO is measuring a source route (H=0),
o The router MUST verify that the Address[Index] element lists one o The router MUST verify that the Address[Index] element lists one
of its unicast IPv6 addresses, failing which the router MUST of its unicast IPv6 addresses, failing which the router MUST
discard the MO packet with no further processing; discard the MO packet with no further processing;
o The router MUST then increment the Index field and use the o The router MUST then increment the Index field and use the
Address[Index] element as the next hop. If Index is greater than Address[Index] element as the next hop. If Index is greater than
Num, the router MUST use the Target Address as the next hop. Num, the router MUST use the Target Address as the next hop.
An intermediate router MUST discard the MO packet with no further To prevent loops, an intermediate router MUST discard the MO packet
processing if the next hop address is not on-link or is not a unicast with no further processing if the Address vector includes multiple
address. To prevent loops, an intermediate router MUST check if the IPv6 addresses assigned to the router's interfaces and if such
Address vector includes multiple IPv6 addresses assigned to the addresses do not appear back to back inside the Address vector.
router's interfaces and if such addresses do not appear back to back
inside the Address vector. In this case, the router MUST discard the
MO packet with no further processing.
5.2. Determining Next Hop For An MO Measuring A Hop-by-hop Route 5.2. Determining Next Hop For An MO Measuring A Hop-by-hop Route
If the received MO is measuring a hop-by-hop route (H=1), the router If the received MO is measuring a hop-by-hop route (H=1), the router
MUST use the RPLInstanceID, the Target Address and, if RPLInstanceID MUST use the RPLInstanceID, the Target Address and, if RPLInstanceID
is a local value, the Origin Address to determine the next hop for is a local value, the Origin Address to determine the next hop for
the MO. Moreover, the MO. Moreover,
o If the RPLInstanceID of the hop-by-hop route is a local value and o If the RPLInstanceID of the hop-by-hop route is a local value and
the A flag is set, the router MUST check if the Address vector the A flag is set, the router MUST check if the Address vector
already contains one of its IPv6 addresses. If yes, the router already contains one of its IPv6 addresses. If yes, the router
MUST discard the packet with no further processing. Otherwise, MUST discard the packet with no further processing. Otherwise,
the router MUST store one of its IPv6 addresses (after eliding the router MUST store one of its IPv6 addresses (after eliding
Compr prefix octets) at location Address[Index] and then increment Compr prefix octets) at location Address[Index] and then increment
the Index field. the Index field.
o If the router is the root of the non-storing DAG along which the o If the router is the root of the non-storing global DAG along
received MO message has been traveling so far, the router MUST do which the received MO message had been traveling so far,
the following:
* Reset the H, A and R flags. * The router discards the MO packet with no further processing if
it does not know of a source route to reach the target
(specified by the Target Address listed in the packet).
* Remove any existing Address vector inside the MO. * Otherwise, the router MUST do the following:
* Insert a new Address vector inside the MO and specify a source + Set the H, A and R flags to zero and the RPLInstanceID field
route to the target inside the Address vector as per the to binary value 10000000.
following rules:
+ The Address vector MUST contain a complete route from the + Remove any existing Address vector inside the MO.
router to the target (excluding the router and the target);
+ The IPv6 addresses (with Compr prefix octets elided) in the + Insert a new Address vector inside the MO and specify a
Address vector MUST be accessible in the forward direction, source route to the target inside the Address vector as per
i.e., towards the target; the following rules:
+ To prevent loops in the source route, the router MUST ensure - The Address vector MUST contain a complete route from the
that router to the target (excluding the router and the
target);
- Any IPv6 address MUST NOT appear more than once in the - The IPv6 addresses (with Compr prefix octets elided) in
Address vector; the Address vector MUST be reachable in the forward
direction, i.e., towards the target;
- If the Address vector includes multiple IPv6 addresses - To prevent loops in the source route, the router MUST
assigned to the router's interfaces, such addresses MUST ensure that
appear back to back inside the Address vector.
+ Each address appearing in the Address vector MUST be a o Any IPv6 address MUST NOT appear more than once in the
unicast address. Address vector;
* Specify in the Num field the number of address elements in the o If the Address vector includes multiple IPv6 addresses
Address vector. assigned to the router's interfaces, such addresses
MUST appear back to back inside the Address vector.
* Set the Index field to 1. - Each address appearing in the Address vector MUST be a
unicast address.
+ Specify in the Num field the number of address elements in
the Address vector.
+ Set the Index field to one.
6. Processing a Measurement Request at the Target 6. Processing a Measurement Request at the Target
On receiving an MO, if a router chooses to process the packet further On receiving an MO, if a router chooses to process the packet further
and finds one of its unicast IPv6 addresses listed as the Target and finds one of its unicast IPv6 addresses listed as the Target
Address, the router considers itself the target and MUST process the Address, the router considers itself the target and MUST process the
received MO in the following manner. received MO in the following manner.
The target MUST discard the packet with no further processing if the The target MUST discard the packet with no further processing if the
received MO is not a Measurement Request. received MO is not a Measurement Request.
The target MUST update the routing metric objects in the Metric The target 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 likely a response to an earlier Measurement Request that the is likely a response to an earlier Measurement Request that the
target had sent to the origin with B flag set to 1). target had sent to the origin with B flag set to one).
The target MUST generate a Measurement Reply message. The The target MUST generate a Measurement Reply message. The
Measurement Reply message MUST have the same SequenceNo field as the Measurement Reply message MUST have the same SequenceNo field as the
received Measurement Request message. The received Measurement received Measurement Request message. The received Measurement
Request message can be trivially converted into the Measurement Reply Request message can be trivially converted into the Measurement Reply
by reseting the T flag to zero. The target MAY remove the Address by setting the T flag to zero. The target MAY remove the Address
vector from the Measurement Reply if desired. The target MUST then vector from the Measurement Reply if desired. The target MUST then
unicast the Measurement Reply back to the origin: unicast the Measurement Reply back to the origin:
o If the Measurement Request traveled along a DAG with a global o If the Measurement Request traveled along a global DAG (i.e., one
RPLInstanceID, the Measurement Reply MAY be unicast back to the with a global RPLInstanceID), the Measurement Reply MAY be unicast
origin along the same DAG. back to the origin 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 the A flag inside the received message a local RPLInstanceID and the A flag inside the received message
is set to 1, the target MAY reverse the source route contained in is set to one, the target MAY reverse the source route contained
the Address vector and use it to send the Measurement Reply back in the Address vector and use it to send the Measurement Reply
to the origin. back to the origin.
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 R
flag inside the received message is set to 1, the target MAY flag inside the received message is set to one, the target MAY
reverse the source route contained in the Address vector and use reverse the source route contained in the Address vector and use
it to send the Measurement Reply back to the origin. it to send the Measurement Reply back to the origin.
If the B flag in the received Measurement Request is set to 1, the If the B flag in the received Measurement Request is set to one, the
target MAY generate a new Measurement Request to measure the cost of target SHOULD generate a new Measurement Request to measure the cost
its current (or the most preferred) route to the origin. The routing of its current (or the most preferred) route to the origin. The
metrics used in the new Measurement Request MUST include the routing routing metrics used in the new Measurement Request MUST include the
metrics specified in the received Measurement Request. routing metrics specified in the received Measurement Request.
7. Processing a Measurement Reply at the Origin 7. Processing a Measurement Reply at the Origin
When a router receives an MO, it examines if one of its unicast IPv6 When a router receives an MO, it examines if one of its unicast IPv6
addresses is listed as the Origin Address. If yes, the router is the addresses is listed as the Origin Address. If yes, the router is the
origin and MUST process the received message in the following manner. origin and MUST process the received message in the following manner.
The origin MUST discard the packet with no further processing if the The origin MUST discard the packet with no further processing if the
received MO is not a Measurement Reply or if the origin has no received MO is not a Measurement Reply or if the origin has no
recollection of sending a Measurement Request with the sequence recollection of sending a Measurement Request with the sequence
skipping to change at page 16, line 13 skipping to change at page 16, line 47
The origin MUST examine the routing metric objects inside the Metric The origin MUST examine the routing metric objects inside the Metric
Container options to evaluate the quality of the measured P2P route. Container options to evaluate the quality of the measured P2P route.
If a routing metric object contains local metric values recorded by If a routing metric object contains local metric values recorded by
routers on the route, the origin MUST aggregate these local values routers on the route, the origin MUST aggregate these local values
into an end-to-end value as per the aggregation rules for the metric. into an end-to-end value as per the aggregation rules for the metric.
8. Security Considerations 8. Security Considerations
The mechanism defined in this document can potentially be used by a The mechanism defined in this document can potentially be used by a
compromised router to generate bogus Measurement Requests to compromised router to generate bogus Measurement Requests to
arbitrary target routers. Such Measurement Requests may cause arbitrary target routers. Such Measurement Requests may cause CPU
processing overload in the routers in the network, drain their overload in the routers in the network, drain their batteries and
batteries and cause traffic congestion in the network. Note that cause traffic congestion in the network. Note that some of these
some of these problems would occur even if the compromised router problems would occur even if the compromised router were to generate
were to generate bogus data traffic to arbitrary destinations. bogus data traffic to arbitrary destinations.
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 header [RFC5095] may be valid here. To
address such concerns, the mechanism described in this document address such concerns, the mechanism described in this document
includes several remedies: includes several remedies:
o This document requires that a route inserted inside the Address o This document requires that a route inserted inside the Address
vector must be a strict source route and must not include any vector must be a strict source route and must not include any
multicast addresses. multicast addresses.
o This document requires that an MO message must not cross the o This document requires that an MO message must not cross the
boundaries of the RPL Instance where it originated. A router must boundaries of the RPL routing domain where it originated. A
drop a received MO message if it is not aware of the RPL Instance router must not forward a received MO message further if the next
referred to in the message. Hence, any security problems hop belongs to a different RPL routing domain. Hence, any
associated with the mechanism would be limited to one RPL security problems associated with the mechanism would be limited
Instance. to one RPL routing domain.
o This document requires that a router must drop a received MO o This document requires that a router must drop a received MO
message if the next hop address is not on-link or if it is not a message if the next hop address is not on-link or if it is not a
unicast address. unicast address.
o This document requires that a router must check the source route o This document requires that a router must check the source route
inside the Address vector of each received MO message to ensure inside the Address vector of each received MO message to ensure
that it does not contain a loop involving the router. The router that it does not contain a loop involving the router. The router
must drop the received packet if the source route does contain must drop the received packet if the source route does contain
such a loop. This and the previous two rules protect the network such a loop. This and the previous two rules protect the network
skipping to change at page 17, line 38 skipping to change at page 18, line 23
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
11.2. Informative References 11.2. Informative References
[I-D.ietf-roll-p2p-rpl] [I-D.ietf-roll-p2p-rpl]
Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J. Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J.
Martocci, "Reactive Discovery of Point-to-Point Routes in Martocci, "Reactive Discovery of Point-to-Point Routes in
Low Power and Lossy Networks", draft-ietf-roll-p2p-rpl-08 Low Power and Lossy Networks", draft-ietf-roll-p2p-rpl-09
(work in progress), March 2012. (work in progress), March 2012.
[I-D.ietf-roll-routing-metrics] [I-D.ietf-roll-routing-metrics]
Barthel, D., Vasseur, J., Pister, K., Kim, M., and N. Barthel, D., Vasseur, J., Pister, K., Kim, M., and N.
Dejean, "Routing Metrics used for Path Calculation in Low Dejean, "Routing Metrics used for Path Calculation in Low
Power and Lossy Networks", Power and Lossy Networks",
draft-ietf-roll-routing-metrics-19 (work in progress), draft-ietf-roll-routing-metrics-19 (work in progress),
March 2011. March 2011.
[I-D.ietf-roll-rpl] [I-D.ietf-roll-rpl]
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