--- 1/draft-ietf-roll-p2p-measurement-06.txt 2012-12-24 05:09:47.027708384 +0100 +++ 2/draft-ietf-roll-p2p-measurement-07.txt 2012-12-24 05:09:47.079708366 +0100 @@ -1,49 +1,50 @@ Internet Engineering Task Force M. Goyal, Ed. Internet-Draft University of Wisconsin Intended status: Experimental Milwaukee -Expires: March 21, 2013 E. Baccelli +Expires: June 27, 2013 E. Baccelli INRIA A. Brandt Sigma Designs J. Martocci Johnson Controls - September 17, 2012 + December 24, 2012 - A Mechanism to Measure the Quality of a Point-to-point Route in a Low - Power and Lossy Network - draft-ietf-roll-p2p-measurement-06 +A Mechanism to Measure the Routing Metrics along a Point-to-point Route + in a Low Power and Lossy Network + draft-ietf-roll-p2p-measurement-07 Abstract This document specifies a mechanism that enables an RPL router to - measure the quality of an existing route towards another RPL router - in a low power and lossy network, thereby allowing the router to - decide if it wants to initiate the discovery of a better route. + measure the aggregated values of given routing metrics along an + existing route towards another RPL router in a low power and lossy + network, thereby allowing the router to decide if 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 provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on March 21, 2013. + This Internet-Draft will expire on June 27, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -52,48 +53,56 @@ include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. The Measurement Object (MO) . . . . . . . . . . . . . . . . . 5 - 3.1. Format of the base MO . . . . . . . . . . . . . . . . . . 5 - 3.2. Secure MO . . . . . . . . . . . . . . . . . . . . . . . . 9 - 4. Originating a Measurement Request . . . . . . . . . . . . . . 9 - 4.1. To Measure A Hop-by-hop Route with a Global - RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10 - 4.2. To Measure A Hop-by-hop Route with a Local - RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 10 - 4.3. To Measure A Source Route . . . . . . . . . . . . . . . . 11 - 5. Processing a Measurement Request at an Intermediate Router . . 12 - 5.1. Determining Next Hop For An MO Measuring A Source Route . 14 - 5.2. Determining Next Hop For An MO Measuring A Hop-by-hop - Route . . . . . . . . . . . . . . . . . . . . . . . . . . 14 - 6. Processing a Measurement Request at the Target . . . . . . . . 15 - 7. Processing a Measurement Reply at the Origin . . . . . . . . . 16 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 - 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 - 11.1. Normative References . . . . . . . . . . . . . . . . . . . 18 - 11.2. Informative References . . . . . . . . . . . . . . . . . . 18 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 + 3.1. Format of the base MO . . . . . . . . . . . . . . . . . . 6 + 3.2. Secure MO . . . . . . . . . . . . . . . . . . . . . . . . 10 + 4. Originating a Measurement Request . . . . . . . . . . . . . . 10 + 4.1. When Measuring A Hop-by-hop Route with a Global + RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 11 + 4.2. When Measuring A Hop-by-hop Route with a Local + RPLInstanceID With Route Accumulation Off . . . . . . . . 12 + 4.3. When Measuring A Hop-by-hop Route with a Local + RPLInstanceID With Route Accumulation On . . . . . . . . . 13 + 4.4. When Measuring A Source Route . . . . . . . . . . . . . . 14 + 5. Processing a Measurement Request at an Intermediate Point . . 15 + 5.1. When Measuring A Hop-by-hop Route with a Global + RPLInstanceID . . . . . . . . . . . . . . . . . . . . . . 16 + 5.2. When Measuring A Hop-by-hop Route with a Local + RPLInstanceID With Route Accumulation Off . . . . . . . . 17 + 5.3. When Measuring A Hop-by-hop Route with a Local + RPLInstanceID With Route Accumulation On . . . . . . . . . 18 + 5.4. When Measuring A Source Route . . . . . . . . . . . . . . 19 + 5.5. Final Processing . . . . . . . . . . . . . . . . . . . . . 19 + 6. Processing a Measurement Request at the End Point . . . . . . 20 + 6.1. Generating the Measurement Reply . . . . . . . . . . . . . 20 + 7. Processing a Measurement Reply at the Start Point . . . . . . 21 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 + 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 + 11.1. Normative References . . . . . . . . . . . . . . . . . . . 23 + 11.2. Informative References . . . . . . . . . . . . . . . . . . 24 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 1. Introduction Point to point (P2P) communication between arbitrary routers in a Low power and Lossy Network (LLN) is a key requirement for many - applications [RFC5826][RFC5867]. RPL [RFC6550], the IPv6 Routing - Protocol for LLNs, constrains the LLN topology to a Directed Acyclic + applications [RFC5826][RFC5867]. The IPv6 Routing Protocol for LLNs + (RPL) [RFC6550] constrains the LLN topology to a Directed Acyclic Graph (DAG) built to optimize the routing costs to reach the DAG's root. The P2P routing functionality, available under RPL, has the following key limitations: o The P2P routes are restricted to use the DAG links only. Such P2P routes may potentially be suboptimal and may lead to traffic congestion near the DAG root. o RPL is a proactive routing protocol and hence requires all P2P routes to be established ahead of the time they are used. Many @@ -124,670 +133,899 @@ discovery. Note that it is important that the routing constraints are not overly strict; otherwise the P2P-RPL route discovery may fail even though a route, much better than the one currently being used, exists. This document specifies a mechanism that enables an RPL router to measure the aggregated values of the routing metrics along an 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 and determine the routing constraints to be used for this purpose. + Thus, the utility of this mechanism is dependent on the existence of + P2P-RPL, which is targeting publication as an Experimental RFC. It + makes sense, therefore, for this document also to target publication + as an Experimental RFC. As more operational experience is gained + using P2P-RPL, it is hoped that the mechanism described in this + document will also be used, and feedback will be provided to the ROLL + working group on the utility and benefits of this document. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. - Additionally, this document uses terminology from [RFC6550] and - [I-D.ietf-roll-p2p-rpl]. The following terms, originally defined in - [I-D.ietf-roll-p2p-rpl], are redefined in the following manner. + This document uses terminology from [RFC6550] and + [I-D.ietf-roll-p2p-rpl]. Additionally, this document defines the + following terms. - Origin: The Origin refers to the RPL router that initiates the - measurement process defined in this document and is the start point - of the P2P route being measured. + Start Point: The Start Point refers to the RPL router that initiates + the measurement process defined in this document and is the start + point of the P2P route being measured. - Target: The Target refers to the RPL router at the end point of the - P2P route being measured. + End Point: The End Point refers to the RPL router at the end point of + the P2P route being measured. - Intermediate Router: An RPL router, other than the Origin and the - Target, on the P2P route being measured. + Intermediate Point: An RPL router, other than the Start Point and the + End Point, on the P2P route being measured. + + The following terms, already defined in [I-D.ietf-roll-p2p-rpl], have + been redefined in this document in the following manner. + + Forward direction: The direction from the Start Point to the End + Point. + + Backward direction: The direction from the End Point to the Start + Point. 2. Overview - The mechanism described in this document can be used by an Origin in - an LLN to measure the aggregated values of some routing metrics along - a P2P route to a Target within the LLN. The route is measured in the - direction from the Origin to the Target. Such a route could be a - source route or a hop-by-hop route established using RPL [RFC6550] or - P2P-RPL [I-D.ietf-roll-p2p-rpl]. The Origin decides what metrics to - measure and sends a Measurement Request message, carrying the desired - routing metric objects, along the route. On receiving a Measurement - Request, an Intermediate Router updates the routing metric values - inside the message and forwards it to the next hop on the route. - Thus, the Measurement Request accumulates the values of the routing - metrics for the complete route as it travels towards the Target. - Upon receiving the Measurement Request, the Target unicasts a - Measurement Reply message, carrying the accumulated values of the - routing metrics, back to the Origin. Optionally, the Origin may - allow an Intermediate Router to generate the Measurement Reply if it - already knows the relevant routing metric values along rest of the - route. + The mechanism described in this document can be used by a Start Point + 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 + is measured in the Forward direction. Such a route could be a Source + Route [I-D.ietf-roll-p2p-rpl] or a Hop-by-hop Route + + [I-D.ietf-roll-p2p-rpl] established using RPL [RFC6550] or P2P-RPL + [I-D.ietf-roll-p2p-rpl]. Such a route could also be a "mixed" route + with the initial part consisting of hop-by-hop ascent to the root of + a non-storing DAG [RFC6550] and the final part consisting of a + source-routed descent to the End Point. The Start Point decides what + metrics to measure and sends a Measurement Request message, carrying + the desired routing metric objects, along the route. On receiving a + Measurement Request, an Intermediate Point updates the routing metric + values inside the message and forwards it to the next hop on the + route. Thus, the Measurement Request accumulates the values of the + routing metrics for the complete route as it travels towards the End + Point. The Measurement Request may also accumulate a Source Route + that the End Point may use to reach the Start Point. Upon receiving + the Measurement Request, the End Point unicasts a Measurement Reply + message, carrying the accumulated values of the routing metrics, back + to the Start Point. Optionally, the Start Point may allow an + Intermediate Point to generate the Measurement Reply if the + Intermediate Point already knows the relevant routing metric values + along rest of the route. 3. The Measurement Object (MO) This document defines two new RPL Control Message types, the Measurement Object (MO), with code TBD1, and the Secure MO, with code TBD2. An MO serves as both Measurement Request and Measurement Reply. 3.1. Format of the base MO 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RPLInstanceID | Compr |T|H|A|R|B|I| SequenceNo| Num | Index | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | - | Origin Address | + | Start Point Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | - | Target Address | + | End Point Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Address[1..Num] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Metric Container Option(s) . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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 following fields: - o RPLInstanceID: This field is relevant only if a hop-by-hop route - is being measured, i.e., the H flag, described subsequently, is - set to one. In this case, the Origin MUST set this field to the - RPLInstanceID of the hop-by-hop route being measured. If a source - route is being measured, the Origin MUST set this field to binary - value 10000000. An Intermediate Router MUST set the RPLInstanceID - field in the outgoing MO packet to the same value that it had in - the corresponding incoming MO packet unless it is the root of a - 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 RPLInstanceID: This field specifies the RPLInstanceID of the Hop- + by-hop Route along which the Measurement Request travels (or + traveled initially until it switched over to a Source Route). o Compr: In many LLN deployments, IPv6 addresses share a well known, common prefix. In such cases, the common prefix can be elided - when specifying IPv6 addresses in the Origin/Target Address fields - and the Address vector. The "Compr" field, a 4-bit unsigned - integer, is set by the Origin to specify the number of prefix - octets that are elided from the IPv6 addresses in Origin/Target - Address fields and the Address vector. An Intermediate Router - MUST set the Compr field in the outgoing MO packet to the same - value that it had in the corresponding incoming MO packet. The - Intermediate Router MUST drop the received MO message if the Compr - 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. + when specifying IPv6 addresses in the Start Point/End Point + Address fields and the Address vector. The "Compr" field, a 4-bit + unsigned integer, is set by the Start Point to specify the number + of prefix octets that are elided from the IPv6 addresses in Start + Point/End Point Address fields and the Address vector. The Start + Point will set the Compr value to zero if full IPv6 addresses are + to be carried in the Start Point Address/End Point Address fields + and the Address vector. 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 Reply. - o Hop-by-hop (H): The Origin MUST set this flag to one if the route - being measured is a hop-by-hop route. In that case, the hop-by- - hop route is identified by the RPLInstanceID and, if the - RPLInstanceID is a local value, the Origin Address and Target - Address fields inside the message. The Origin MUST set this flag - to zero if the route being measured is a source route specified in - the Address vector. An Intermediate Router MUST set the H flag in - an outgoing MO packet to the same value that it had in the - corresponding incoming MO packet unless the router is the root of - the 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 reset - the H flag to zero in the outgoing MO packet. + 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. + In that case, the Hop-by-hop Route is identified by the + RPLInstanceID, the End Point Address and, if the RPLInstanceID is + a local value, the Start Point Address (required to be same as the + DODAGID of the route being measured) fields inside the Measurement + Request. The Start Point MUST set this flag to zero if the route + being measured is a Source Route specified in the Address vector. + An Intermediate Point MUST set the H flag in an outgoing + Measurement Request to the same value that it had in the + corresponding incoming Measurement Request unless it is the root + of the non-storing global DAG, identified by the RPLInstanceID, + along which the Measurement Request had been traveling so far and + the Intermediate Point intends to insert a Source Route inside the + Address vector to direct it towards the End Point. In that case, + the Intermediate Point MUST set the H flag to zero. - o Accumulate Route (A): This flag is relevant only if the MO - represents a Measurement Request that travels along a hop-by-hop - route represented by a local RPLInstanceID. In other words, this - 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 set to - zero. A value 1 in this flag indicates that the Measurement - Request MUST accumulate a source route for use by the Target to - send the Measurement Reply back to the Origin. In this case, an - Intermediate Router MUST add its unicast IPv6 address (after - eliding Compr number of prefix octets) to the Address vector in - the manner specified later. Route accumulation is not allowed - when the Measurement Request travels along a hop-by-hop route with - a global RPLInstanceID, i.e., along a global DAG, because: + o Accumulate Route (A): A value 1 in this flag indicates that the + Measurement Request is accumulating a Source Route for use by the + End Point to send the Measurement Reply back to the Start Point. + Route accumulation is allowed (i.e., this flag MAY be set to one) + inside a Measurement Request only if it travels along a Hop-by-hop + Route represented by a local RPLInstanceID (i.e., H = 1, + RPLInstanceID has a local value). In this case, an Intermediate + Point adds its unicast IPv6 address (after eliding Compr number of + prefix octets) to the Address vector in the manner specified in + Section 5.3. In other cases, this flag MUST be set to zero on + transmission and ignored on reception. Route accumulation is not + allowed when the Measurement Request travels along a Hop-by-hop + Route with a global RPLInstanceID, i.e., along a global DAG, + because: - * The DAG's root may need the Address vector to insert a source - route to the Target; and + * The DAG's root may need the Address vector to insert a Source + Route to the End Point; and - * The Target can presumably reach the Origin along this global - DAG. + * The End Point can presumably reach the Start Point along this + global DAG (identified by the RPLInstanceID field). - o Reverse (R): This flag is relevant only if the MO represents a - Measurement Request that travels along a source route, specified - in the Address vector, to the Target. In other words, this flag - MAY be set to one only if T = 1 and H = 0. Otherwise, this flag - 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 - the Target, which can be used, after reversal, by the Target to - source route the Measurement Reply message back to the Origin. + o Reverse (R): A value 1 in this flag inside a Measurement Request + indicates that the Address vector contains a complete Source Route + from the Start Point to the End Point, which can be used, after + reversal, by the End Point to send the Measurement Reply back to + the Start Point. This flag MAY be set to one inside a Measurement + Request only if a Source Route, from the Start Point to the End + Point, is being measured. Otherwise, this flag MUST be set to + zero on transmission and ignored on reception. - 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 - this flag to one to make such a request to the Target. An - Intermediate Router MUST set the B flag in an outgoing MO packet - to the same value that it had in the corresponding incoming MO - packet. On receiving a Measurement Request with the B flag set to - one, the Target SHOULD generate a Measurement Request to measure - the cost of its current (or the most preferred) route to the - Origin. Receipt of this Measurement Request would allow the - Origin to know the cost of the back route from the Target to - itself and thus determine the round-trip cost of reaching the - Target. + o Back Request (B): A value 1 in this flag serves as a request to + the End Point to send a Measurement Request towards the Start + Point. On receiving a Measurement Request with the B flag set to + one, the End Point SHOULD generate a Measurement Request 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 to know the cost of the back route from the End + Point to itself and thus determine the round-trip cost of reaching + the End Point. - o Intermediate Reply (I): Relevant only if a hop-by-hop route is - being measured, this flag serves as a permission to an - Intermediate Router to generate a Measurement Reply if it knows - the cost of the rest of the route being measured. The Origin MAY - set this flag to one if a hop-by-hop route is being measured - (i.e., H = 1) and the Origin wants to allow an Intermediate Router - to generate the Measurement Reply in response to this Measurement - Request. Setting this flag to one may be useful in scenarios - where the Hop Count [RFC6551] is the routing metric of interest - and the Origin expects an Intermediate Router (e.g. the root of a - non-storing DAG or a common ancestor of the Origin and the Target - in a storing DAG) to know the Hop Count of the remainder of the - route to the Target. This flag MUST be set to zero if the route - being measured is a source route (i.e., H = 0). + o Intermediate Reply (I): A value 1 in this flag serves as a + permission to an Intermediate Point to generate a Measurement + Reply if it knows the aggregated values of the routing metrics + being measured for the rest of the route. Setting this flag to + one may be useful in scenarios where the Hop Count [RFC6551] is + the routing metric of interest and an Intermediate Point (e.g. the + root of a non-storing global DAG or a common ancestor of the Start + Point and the End Point in a storing global DAG) may know the Hop + Count of the remainder of the route to the End Point. This flag + MAY be set to one only if a Hop-by-hop Route with a global + RPLInstanceID is being measured (i.e., H = 1, RPLInstanceID has a + global value). Otherwise, this flag MUST be set to zero on + transmission and ignored on reception. - o SequenceNo: A 6-bit sequence number, assigned by the Origin, that - allows the Origin to uniquely identify a Measurement Request and - the corresponding Measurement Reply. An Intermediate Router MUST - 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 - this field in a Measurement Reply message to the same value that - it had in the corresponding Measurement Request message. + o SequenceNo: A 6-bit sequence number, assigned by the Start Point, + that allows the Start Point to uniquely identify a Measurement + Request and the corresponding Measurement Reply. o Num: This field indicates the number of elements, each (16 - Compr) octets in size, inside the Address vector. If the 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 - route contained in the Address vector (T=1,H=0), this field + o Index: If the Measurement Request is traveling along a Source + 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 - route. If the Measurement Request is traveling along a hop-by-hop - 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 - field indicates the index in the Address vector where an - Intermediate Router receiving the MO message must store its IPv6 + route. If the Measurement Request is traveling along a Hop-by-hop + Route with a local RPLInstanceID and the Route Accumulation is on + (i.e., H = 1, RPLInstanceID has a local value, A = 1), this field + indicates the index in the Address vector where an Intermediate + Point receiving the Measurement Request must store its IPv6 address. Otherwise, this field MUST be set to zero on transmission and ignored on reception. - o Origin Address: A unicast IPv6 address of the Origin after eliding - Compr number of prefix octets. If the MO is traveling along a - hop-by-hop route and the RPLInstanceID field indicates a local - value, the Origin Address field MUST specify the DODAGID value - that, along with the RPLInstanceID and the Target Address, - uniquely identifies the hop-by-hop route being measured. + o Start Point Address: A unicast IPv6 address of the Start Point + after eliding Compr number of prefix octets. If the Measurement + Request is traveling along a Hop-by-hop Route and the + RPLInstanceID field indicates a local value, the Start Point + Address field MUST specify the DODAGID value that, along with the + RPLInstanceID and the End Point Address, uniquely identifies the + Hop-by-hop Route being measured. - o Target Address: A unicast IPv6 address of the Target after eliding - Compr number of prefix octets. + o End Point Address: A unicast IPv6 address of the End Point after + eliding Compr number of prefix octets. - o Address[1..Num]: A vector of unicast IPv6 addresses (with Compr - number of prefix octets elided) representing a source route to the - Target: + o Address[0..Num-1]: A vector of unicast IPv6 addresses (with Compr + number of prefix octets elided) representing a Source Route: * Each element in the vector has size (16 - Compr) octets. * The total number of elements inside the Address vector is given by the Num field. - * When the Measurement Request is traveling along a hop-by-hop - route with local RPLInstanceID and has the A flag set, the - Address vector is used to accumulate a source route to be used - by the Target to send the Measurement Reply back to the Origin. - In this case, the route MUST be accumulated in the forward - direction, i.e., from the Origin to the Target. The Target - router would reverse this route to obtain a source route from - itself to the Origin. The IPv6 addresses in the accumulated - route MUST be reachable in the backward direction, i.e., from - the Target to the Origin. An Intermediate Router adding its - address to the Address vector MUST ensure that its address does - not already exist in the vector. + * When the Measurement Request is traveling along a Hop-by-hop + Route with local RPLInstanceID and has the A flag set to one + (i.e., H = 1, RPLInstanceID has a local value, A = 1), the + Address vector is used to accumulate a Source Route that can be + used by the End Point, after reversal, to send the Measurement + Reply back to the Start Point. The route MUST be accumulated + in the Forward direction but the IPv6 addresses in the + accumulated route MUST be reachable in the Backward direction. + An Intermediate Point adding its address to the Address vector + MUST ensure that a routing loop involving this router does not + exist in the accumulated route. - * When the Measurement Request is traveling along a source route, - the Address vector MUST contain a complete route to the Target - and the IPv6 addresses in the Address vector MUST be reachable - in the forward direction, i.e., from the Origin to the Target. - A router (Origin or an Intermediate Router) inserting an - Address vector inside an MO MUST ensure that no address appears - more than once inside the vector. Each router on the way MUST - 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 - Address vector represents a complete route from the Origin to - the Target and this route can be used after reversal by the - Target to send the Measurement Reply message back to the Origin - (i.e., the IPv6 addresses in the Address vector are reachable - in the backward direction - from the Target to the Origin). + * When the Measurement Request is traveling along a Source Route + (i.e., H = 0), the Address vector MUST contain a complete route + to the End Point and the IPv6 addresses in the Address vector + MUST be reachable in the Forward direction. A router (the + Start Point or an Intermediate Point) inserting an Address + vector inside a Measurement Request MUST ensure that no address + appears more than once inside the vector. Each router on the + way MUST ensure that a routing loop involving this router does + not exist within the Source Route. The Start Point MAY set the + R flag in the Measurement Request if the route in the Address + vector represents a complete route from the Start Point to the + End Point and this route can be used by the End Point, after + reversal, to send the Measurement Reply message back to the + Start Point (i.e., the IPv6 addresses in the Address vector are + reachable in the Backward direction). - * The Origin and Target addresses MUST NOT be included in the - Address vector. + * The Start Point and End Point addresses MUST NOT be included in + the Address vector. * The Address vector MUST NOT contain any multicast addresses. - o Metric Container Options: An MO MUST contain one or more Metric - Container options to accumulate the routing metric values for the - route being measured. + o Metric Container Options: A Measurement Request MUST contain one + or more Metric Container options [RFC6550] to accumulate the + values of the selected routing metrics in the manner described in + [RFC6551] for the route being measured. + + Section 4 describes how does a Start Point set various fields inside + a Measurement Request in different cases. Section 5 describes how + does an Intermediate Point process a received Measurement Request + before forwarding it further. Section 6 describes how does the End + Point process a received Measurement Request and generate a + Measurement Reply. Finally, Section 7 describes how does the Start + Point process a received Measurement Reply. 3.2. Secure MO - A Secure MO message follows the format in Figure 7 of [RFC6550], - where the base format is the base MO shown in Figure 1. + A Secure MO follows the format in Figure 7 of [RFC6550], where the + base format is the base MO shown in Figure 1. 4. Originating a Measurement Request - 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 - 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 - the T flag to one to indicate that the MO represents a Measurement - Request. The Origin MUST also include the routing metric objects of - interest inside one or more Metric Container options inside the MO. - Depending on the metrics being measured, the Origin must also - initiate these routing metric objects by including the values of the - routing metrics for the first hop on the P2P route being measured. - - After setting the MO fields appropriately, the Origin determines the - 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: + A Start Point sets various fields inside the Measurement Request it + generates in the manner described below. The Start Point MUST also + include the routing metric objects [RFC6551] of interest inside one + or more Metric Container options inside the Measurement Request. The + 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 + is determined using the RPLInstanceID, the End Point Address and, if + RPLInstanceID is a local value, the Start Point Address fields in the + Measurement Request. If a Source Route is being measured (i.e., H = + 0), the Address[0] element inside the Measurement Request contains + the next hop address. The Start Point MUST discard the Measurement + Request 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. + o the next hop is not in the same RPL routing domain as the Start + Point. - Otherwise, the Origin MUST unicast the MO message to the next hop on - the P2P route. + Otherwise, depending on the routing metrics, the Start Point must + initiate the routing metric objects inside the Metric Container + options by including the routing metric values for the first hop on + the route being measured. Finally, the Start Point MUST unicast the + Measurement Request to the next hop on the route being measured. -4.1. To Measure 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, - the MO message MUST NOT contain the Address vector and the following - MO fields MUST be set in the manner specified below: + 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 + contain an Address vector and various MO fields MUST be set in the + following manner: - o Hop-by-hop (H): This flag MUST be set to one. + o RPLInstanceID: MUST be set to the RPLInstanceID of the route being + measured. + + o Compr: MUST be set to specify the number of prefix octets that are + elided from the IPv6 addresses in Start Point/End Point Address + fields. + + o Type (T): MUST be set to one since the MO represents a Measurement + Request. + + o Hop-by-hop (H): MUST be set to one. o Accumulate Route (A): 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 + Point to send a Measurement Request to the Start Point. + + o Intermediate Reply (I): This flag MAY be set to one if the Start + Point expects an Intermediate Point to know the values of the + routing metrics being measured for the remainder of the route. + + o SequenceNo: Assigned by the Start Point so that it can uniquely + identify the Measurement Request and the corresponding Measurement + Reply. + o Num: This field MUST be set to zero. o Index: This field MUST be set to zero. -4.2. To Measure A Hop-by-hop Route with a Local RPLInstanceID + o Start Point Address: MUST be set to a unicast IPv6 address of the + Start Point after eliding Compr number of prefix octets. - 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, - the MO message MUST NOT contain the Address vector and the following - MO fields MUST be set in the manner specified below: + o End Point Address: MUST be set to a unicast IPv6 address of the + End Point after eliding Compr number of prefix octets. - o Hop-by-hop (H): This flag MUST be set to one. +4.2. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With + Route Accumulation Off + + 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 + 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: + + o RPLInstanceID: MUST be set to the RPLInstanceID of the route being + measured. + + o Compr: MUST be set to specify the number of prefix octets that are + elided from the IPv6 addresses in Start Point/End Point Address + fields. + + o Type (T): MUST be set to one since the MO represents a Measurement + Request. + + o Hop-by-hop (H): MUST be set to one. o Accumulate Route (A): 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 + Point to send a Measurement Request to the Start Point. + + o Intermediate Reply (I): This flag MUST be set to zero. + + o SequenceNo: Assigned by the Start Point so that it can uniquely + identify the Measurement Request and the corresponding Measurement + Reply. + o Num: This field MUST be set to zero. o Index: This field MUST be set to zero. - o Origin Address: This field MUST contain the DODAGID value (after - eliding Compr number of prefix octets) associated with the route - being measured. + o Start Point Address: This field MUST contain the DODAGID value + (after eliding Compr number of prefix octets) associated with the + route 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 - Target to send the Measurement Reply message back, it MUST set the - following MO fields in the manner specified below: + o End Point Address: MUST be set to a unicast IPv6 address of the + End Point after eliding Compr number of prefix octets. - o Hop-by-hop (H): This flag MUST be set to one. +4.3. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With + Route Accumulation On + + 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 + the End Point to send the Measurement Reply message back, the MO MUST + contain an Address vector and various MO fields MUST be set in the + following manner: + + o RPLInstanceID: MUST be set to the RPLInstanceID of the route being + measured. + + o Compr: MUST be set to specify the number of prefix octets that are + elided from the IPv6 addresses in Start Point/End Point Address + fields and the Address vector. + + o Type (T): MUST be set to one since the MO represents a Measurement + Request. + + o Hop-by-hop (H): 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 Back Request (B): This flag MAY be set to one to request the End + Point to send a Measurement Request to the Start Point. + o Intermediate Reply (I): This flag MUST be set to zero. + o SequenceNo: Assigned by the Start Point so that it can uniquely + identify the Measurement Request and the corresponding Measurement + Reply. + + o Num: This field MUST specify the number of address elements, each + (16 - Compr) octets in size, that can fit inside the Address + vector. + + 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. + + o Start Point Address: This field MUST contain the DODAGID value + (after eliding Compr number of prefix octets) associated with the + route being measured. + + o End Point Address: MUST be set to a unicast IPv6 address of the + End Point after eliding Compr number of prefix octets. + o Address vector: The Address vector must be large enough to - accomodate a complete source route from the Origin to the Target. - All the bits in the Address vector field MUST be set to zero. + accomodate a complete Source Route from the End Point to the Start + Point. 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 - can fit inside the Address vector. +4.4. When Measuring A Source Route - o Index: This field MUST be set to one. + If a Source Route is being measured, the Start Point MUST set various + MO fields in the following manner: - o Origin Address: This field MUST contain the DODAGID value (after - eliding Compr number of prefix octets) associated with the route - being measured. + o RPLInstanceID: MUST be set to the binary value 10000000. -4.3. To Measure A Source Route + o Compr: MUST be set to specify the number of prefix octets that are + elided from the IPv6 addresses in Start Point/End Point Address + fields and the Address vector. - If a source route is being measured, the Origin MUST set the - following MO fields in the manner specified below: + o Type (T): MUST be set to one since the MO represents a Measurement + Request. - o Hop-by-hop (H): This flag MUST be set to zero. + o Hop-by-hop (H): 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 - the Address vector can be reversed and used by the Target to - source route the Measurement Reply message back to the Origin. + 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 + send the Measurement Reply message back to the Start Point. Otherwise, this flag MUST be set to zero. + o Back Request (B): This flag MAY be set to one to request the End + Point to send a Measurement Request to the Start Point. + o Intermediate Reply (I): This flag MUST be set to zero. + o SequenceNo: Assigned by the Start Point so that it can uniquely + identify the Measurement Request and the corresponding Measurement + Reply. + + o Num: This field MUST specify the number of address elements, each + (16 - Compr) octets in size, inside the Address vector. + + o Index: This field MUST be set to zero to indicate the position in + the Address vector of the next hop on the route. + + o Start Point Address: MUST be set to a unicast IPv6 address of the + Start Point after eliding Compr number of prefix octets. + + o End Point Address: MUST be set to a unicast IPv6 address of the + End Point after eliding Compr number of prefix octets. + o Address vector: - * The Address vector MUST contain a complete route from the - Origin to the Target (excluding the Origin and the Target). + * The Address vector MUST contain a complete Source Route from + the Start Point to the End Point (excluding the Start Point and + the End Point). * The IPv6 addresses (with Compr prefix octets elided) in the - Address vector MUST be reachable in the forward direction, - i.e., from the Origin to the Target. + Address vector MUST be reachable in the Forward direction. * 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. + reachable in the Backward direction. - * To prevent loops in the source route, the Origin MUST ensure + * To avoid loops in the Source Route, the Start Point MUST ensure compliance to the following rules: + Any IPv6 address MUST NOT appear more than once in the Address vector. + If the Address vector includes multiple IPv6 addresses - assigned to the Origin's interfaces, such addresses MUST - appear back to back inside the Address vector. + assigned to the Start Point's interfaces, such addresses + MUST appear back to back inside the Address vector. * Each address appearing in the Address vector MUST be a unicast address. - o Num: This field MUST be set to indicate the number of elements in - the Address vector. - - o Index: This field MUST be set to one. - -5. Processing a Measurement Request at an Intermediate Router +5. Processing a Measurement Request at an Intermediate Point - A router (an Intermediate Router or the Target) 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 policy goals may include the need to reduce the router's CPU load or - to enhance its battery life. + to enhance its battery life or to prevent misuse of this mechanism by + unauthorized nodes. A router MUST discard a received MO with no further processing if the - 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. + value in the Compr field inside the received message is more than + 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 further, it MUST check if one of its IPv6 addresses is listed as - either the Origin or the Target Address. If neither, the router - considers itself an Intermediate Router and MUST process the received - MO in the following manner. + either the Start Point or the End Point Address. If neither, the + router considers itself an Intermediate Point and MUST process the + received MO in the following manner. - An Intermediate Router MUST discard the packet with no further - processing if the received MO is not a Measurement Request. + An Intermediate Point MUST discard the packet with no further + processing if the received MO is not a Measurement Request (i.e., T = + 0). - If the H and I flags are set to one in the received MO and the - Intermediate Router knows the values of the routing metrics, - specified in the Metric Container, for the remainder of the route, it - MAY generate a Measurement Reply on the Target's behalf in the manner - specified in Section 6 (after including in the Measurement Reply the - relevant routing metric values for the complete route being - measured). Otherwise, the Intermediate Router MUST process the - received MO in the following manner. + Next, the Intermediate Point determines the type of the route being + measured (by checking the values of the H flag and the RPLInstanceID + field) and processes the received MO accordingly in the manner + specified next. - The router MUST determine the next hop on the P2P route being - measured in the manner described below. The router MUST drop the MO - with no further processing and MAY send an ICMPv6 Destination - 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 message. The router MUST drop the MO with no further processing: +5.1. When Measuring A Hop-by-hop Route with a Global RPLInstanceID - o If the next hop address is not a unicast address; or + 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 + Point MUST process the received Measurement Request in the following + manner. - o If the next hop is not on-link; or + The Intermediate Point MUST discard the received Measurement Request + with no further processing if the Num field is not set to zero or if + the Address vector is present in the received message. - o If the next hop is not in the same RPL routing domain as the - router. + If the Intermediate Reply (I) flag is set to one in the received + Measurement Request and the Intermediate Point knows the values of + the routing metrics, specified in the Metric Container options, for + the remainder of the route, it MAY generate a Measurement Reply on + the End Point's behalf in the manner specified in Section 6.1 (after + including in the Measurement Reply the relevant routing metric values + for the complete route being measured). Otherwise, the Intermediate + Point MUST process the received message in the following manner. - Next, the router MUST update the routing metric objects, contained in - the Metric Container option(s) 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. An Intermediate Router can - only update the existing metric objects and MUST NOT add any new - routing metric object to the Metric Container. An Intermediate - Router MUST drop the MO if it cannot update a routing metric object - specified inside the Metric Container. + The Intermediate Point MUST then determine the next hop on the route + being measured using the RPLInstanceID and the End Point Address. If + the Intermediate Point is the root of the non-storing global DAG + along which the received Measurement Request had been traveling so + far, it MUST process the received Measurement Request in the + following manner: - After updating the routing metrics, the router MUST unicast the MO to - the next hop. + o The router MUST discard the Measurement Request with no further + processing and MAY send an ICMPv6 Destination Unreachable (with + Code 0 - No Route To Destination) error message to the Start Point + if it does not know how to reach the End Point. -5.1. Determining Next Hop For An MO Measuring A Source Route + o Otherwise, unless the router determines the End Point itself to be + the next hop, the router MUST make the following changes in the + received Measurement Request: - In case the received MO is measuring a source route (H=0), + * Set the H, A, R and I flags to zero (the A and R flags should + already be zero in the received message). - o The router MUST verify that the Address[Index] element lists one - of its unicast IPv6 addresses, failing which the router MUST - discard the MO packet with no further processing; + * Leave remaining fields unchanged (the Num field would be + modified in next steps). Note that the RPLInstanceID field + identifies the non-storing global DAG along which the + Measurement Request traveled so far. This information MUST be + preserved so that the End Point may use this DAG to send the + Measurement Reply back to the Start Point. - o The router MUST then increment the Index field and use the - Address[Index] element as the next hop. If Index is greater than - Num, the router MUST use the Target Address as the next hop. + * Insert a new Address vector inside the Measurement Request and + specify a Source Route to the End Point inside the Address + vector as per the following rules: - To prevent loops, an Intermediate Router MUST discard the MO packet - with no further processing if the Address vector includes multiple - IPv6 addresses assigned to the router's interfaces and if such - addresses do not appear back to back inside the Address vector. + + The Address vector MUST contain a complete route from the + router to the End Point (excluding the router and the End + Point); -5.2. Determining Next Hop For An MO Measuring A Hop-by-hop Route + + The IPv6 addresses (with Compr prefix octets elided) in the + Address vector MUST be reachable in the Forward direction; - 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 - is a local value, the Origin Address to determine the next hop for - the MO. Moreover, + + To avoid loops in the Source Route, the router MUST ensure + that - 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 - already contains one of its IPv6 addresses. If yes, the router - MUST discard the packet with no further processing. Otherwise, - the router MUST store one of its IPv6 addresses (after eliding - Compr prefix octets) at location Address[Index] and then increment - the Index field. + - Any IPv6 address MUST NOT appear more than once in the + Address vector; - o If the router is the root of the non-storing global DAG along - which the received MO message had been traveling so far, + - If the Address vector includes multiple IPv6 addresses + assigned to the router's interfaces, such addresses MUST + appear back to back inside the Address vector. - * 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). + + Each address appearing in the Address vector MUST be a + unicast address. - * Otherwise, the router MUST do the following: + * Specify in the Num field the number of address elements in the + Address vector. - + Set the H, A and R flags to zero and the RPLInstanceID field - to binary value 10000000. + * Set the Index field to zero to indicate the position in the + Address vector of the next hop on the route. Thus, Address[0] + element contains the address of the next hop on the route. - + Remove any existing Address vector inside the MO. + The Intermediate Point MUST then complete the processing of the + received Measurement Request as specified in Section 5.5. - + Insert a new Address vector inside the MO and specify a - source route to the Target inside the Address vector as per - the following rules: +5.2. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With + Route Accumulation Off - - The Address vector MUST contain a complete route from the - router to the Target (excluding the router and the - Target); + 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 + local value, A = 0), the Intermediate Point MUST process the received + Measurement Request in the following manner. - - The IPv6 addresses (with Compr prefix octets elided) in - the Address vector MUST be reachable in the forward - direction, i.e., towards the Target; + The Intermediate Point MUST discard the received Measurement Request + with no further processing if the Num field is not zero or if the + Address vector is present in the received message. - - To prevent loops in the source route, the router MUST - ensure that + The Intermediate Point MUST then determine the next hop on the route + being measured using the RPLInstanceID, the End Point Address and the + Start Point Address (which represents the DODAGID of the route being + measured). The Intermediate Point MUST discard the Measurement + Request with no further processing and MAY send an ICMPv6 Destination + Unreachable (with Code 0 - No Route To Destination) error message to + the Start Point if it can not determine the next hop. Otherwise, the + Intermediate Point MUST complete the processing of the received + Measurement Request as specified in Section 5.5. - o Any IPv6 address MUST NOT appear more than once in the - Address vector; +5.3. When Measuring A Hop-by-hop Route with a Local RPLInstanceID With + Route Accumulation On - o If the Address vector includes multiple IPv6 addresses - assigned to the router's interfaces, such addresses - MUST appear back to back inside the Address vector. + If a Hop-by-hop Route with a local RPLInstanceID is being measured + and the route accumulation in on (i.e., H = 1, RPLInstanceID has a + local value, A = 1), the Intermediate Point MUST process the received + Measurement Request in the following manner. - - Each address appearing in the Address vector MUST be a - unicast address. + The Intermediate Point MUST discard the received Measurement Request + with no further processing if the Num field is set to zero or if the + Address vector is not present in the received message. - + Specify in the Num field the number of address elements in - the Address vector. + The Intermediate Point MUST then determine the next hop on the route + being measured using the RPLInstanceID, the End Point Address and the + Start Point Address (which represents the DODAGID of the route being + measured). The Intermediate Point MUST discard the Measurement + Request with no further processing and MAY send an ICMPv6 Destination + Unreachable (with Code 0 - No Route To Destination) error message to + the Start Point if it can not determine the next hop. The + Intermediate Point MUST drop the received Measurement Request with no + further processing if the index field has value Num - 1 and the next + hop is not same as the End Point. In this case, the next hop would + have no space left in the Address vector to store its address. - + Set the Index field to one. + Otherwise, the Intermediate Point MUST check if adding one of its + IPv6 addresses to the the Address vector would create a routing loop + in the accumulated route. If yes, the router MUST discard the packet + with no further processing. Otherwise, the router MUST store one of + its unicast IPv6 addresses (after eliding Compr prefix octets) at + location Address[Index] and then increment the Index field. The IPv6 + address added to the Address vector MUST be reachable in the Backward + direction. -6. Processing a Measurement Request at the Target + The Intermediate Point MUST then complete the processing of the + received Measurement Request as specified in Section 5.5. - 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 - Address, the router considers itself the Target and MUST process the - received MO in the following manner. +5.4. When Measuring A Source Route - The Target MUST discard the packet with no further processing if the - received MO is not a Measurement Request. + If a Source Route is being measured (i.e., H = 0), the Intermediate + Point MUST process the received Measurement Request in the following + manner. - The Target MUST update the routing metric objects in the Metric + The Intermediate Point MUST discard the received Measurement Request + with no further processing if the Num field is set to zero or if the + Address vector is not present in the received message. + + The Intermediate Point MUST then determine the next hop on the route + being measured in the manner described below. The Intermediate Point + MUST verify that the Address[Index] element lists one of its unicast + IPv6 addresses, failing which it MUST discard the Measurement Request + with no further processing. To prevent loops, the Intermediate Point + MUST discard the Measurement Request with no further processing if + the Address vector includes multiple IPv6 addresses assigned to its + interfaces and if such addresses do not appear back to back inside + the Address vector. The Intermediate Point MUST then increment the + Index field and use the Address[Index] element as the next hop + (unless 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. + + The Intermediate Point MUST then complete the processing of the + received Measurement Request as specified in Section 5.5. + +5.5. Final Processing + + The Intermediate Point MUST drop the received Measurement Request + with no further processing: + + 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 in the same RPL routing domain as the + Intermediate Point. + + Next, the Intermediate Point MUST update the routing metric objects, + inside the Metric Container option(s) inside the Measurement Request, + either by updating the aggregated value for the routing metric or by + attaching the local values for the metric inside the object. An + Intermediate Point can only update the existing metric objects and + MUST NOT add any new routing metric object to the Metric Container. + An Intermediate Point MUST drop the Measurement Request with no + further processing if it cannot update a routing metric object + specified inside the Metric Container. + + Finally, the Intermediate Point MUST unicast the Measurement Request + to the next hop. + +6. Processing a Measurement Request at the End Point + + On receiving an MO, if a router chooses to process the message + further and finds one of its unicast IPv6 addresses listed as the End + Point Address, the router considers itself the End Point and MUST + process the received MO in the following manner. + + The End Point MUST discard the received message with no further + processing if it is not a Measurement Request (i.e., T = 0). + + If the received Measurement Request traveled on a Hop-by-hop Route + with a local RPLInstanceID with route accumulation on (i.e., H = 1, + RPLInstanceID has a local value and A = 1), elements Address[0] + through Address[Index - 1] in the Address vector contain a complete + Source Route from the Start Point to the End Point (excluding the + Start Point and the End Point), which the End Point MAY use, after + reversal, to reach the Start Point. + + 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 + Address[0] through Address[Num - 1] in the Address vector contain a + complete Source Route from the Start Point to the End Point + (excluding the Start Point and the End Point), which the End Point + MAY use, after reversal, to reach the Start Point. + + The End Point MUST update the routing metric objects in the Metric Container options if required and MAY note the measured values for the complete route (especially, if the received Measurement Request - is likely a response to an earlier Measurement Request that the - Target had sent to the Origin with B flag set to one). + is likely a response to an earlier Measurement Request that the End + Point had sent to the Start Point with B flag set to one). - The Target MUST generate a Measurement Reply message. The - Measurement Reply message MUST have the same SequenceNo field as the - received Measurement Request message. The received Measurement - Request message can be trivially converted into the Measurement Reply - by setting the T flag to zero. The Target MAY remove the Address - vector from the Measurement Reply if desired. The Target MUST then - unicast the Measurement Reply back to the Origin: + 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 + Measurement Request, the End Point SHOULD generate a new Measurement + Request to measure the cost of its current (or the most preferred) + route to the Start Point. The routing metrics used in the new + Measurement Request MUST include the routing metrics specified in the + received Measurement Request. - o If the Measurement Request traveled along a global DAG (i.e., one - with a global RPLInstanceID), the Measurement Reply MAY be unicast - back to the Origin along the same DAG. +6.1. Generating the Measurement Reply - o If the Measurement Request traveled along a hop-by-hop route with - a local RPLInstanceID and the A flag inside the received message - is set to one, the Target MAY reverse the source route contained - in the Address vector and use it to send the Measurement Reply - back to the Origin. + A Measurement Reply MUST have the Type (T) flag set to zero and need + not contain the Address vector. The following fields inside a + Measurement Reply MUST have the same values as they had inside the + corresponding Measurement Request: RPLInstanceID, Compr, SequenceNo, + Start Point Address, End Point Address and Metric Container + Option(s). The remaining fields inside a Measurement Reply may have + any value and MUST be ignored on reception at the Start Point. The + received Measurement Request MAY trivially be converted into a + Measurement Reply by setting the Type (T) flag to zero. - o If the Measurement Request traveled along a source route and the R - flag inside the received message is set to one, the Target MAY - reverse the source route contained in the Address vector and use - it to send the Measurement Reply back to the Origin. + A Measurement Reply MUST be unicast back to the Start Point: - If the B flag in the received Measurement Request is set to one, the - Target SHOULD generate a new Measurement Request to measure the cost - of its current (or the most preferred) route to the Origin. The - routing metrics used in the new Measurement Request MUST include the - routing metrics specified in the received Measurement Request. + o If the Measurement Request traveled along a global DAG, identified + by the RPLInstanceID field, the Measurement Reply MAY be unicast + back to the Start Point along the same DAG. -7. Processing a Measurement Reply at the Origin + o If the Measurement Request traveled along a Hop-by-hop Route with + a local RPLInstanceID and accumulated a Source Route from the + Start Point to the End Point, this Source Route MAY be used after + reversal to send the Measurement Reply back to the Start Point. + + o If the Measurement Request traveled along a Source Route and the R + flag inside the received message is set to one, the End Point MAY + reverse the Source Route contained in the Address vector and use + it to send the Measurement Reply back to 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 - addresses is listed as the Origin Address. If yes, the router is the - Origin and MUST process the received message in the following manner. + addresses is listed as the Start Point Address. If yes, the router + is the Start Point and MUST process the received message in the + following manner. - 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 - recollection of sending a Measurement Request with the sequence - number listed in the received MO. + The Start Point MUST discard the packet with no further processing if + the received MO is not a Measurement Reply or if the Start Point has + no recollection of sending the corresponding Measurement Request. - The Origin MUST examine the routing metric objects inside the Metric - Container options to evaluate the quality of the measured P2P route. - If a routing metric object contains local metric values recorded by - 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. + The Start Point can use the routing metric objects inside the Metric + Container to evaluate the metrics for the measured P2P route. If a + routing metric object contains local metric values recorded by + 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 + aggregation rules for the specific metric. A Start Point is then + free to interpret the metrics for the route according to its local + policy. 8. Security Considerations The mechanism defined in this document can potentially be used by a - compromised router to generate bogus Measurement Requests to - arbitrary Target routers. Such Measurement Requests may cause CPU - overload in the routers in the network, drain their batteries and - cause traffic congestion in the network. Note that some of these - problems would occur even if the compromised router were to generate - bogus data traffic to arbitrary destinations. + compromised router to send bogus Measurement Requests to arbitrary + End Points. Such Measurement Requests may cause CPU overload in the + routers in the network, drain their batteries and cause traffic + congestion in the network. Note that some of these problems would + occur even if the compromised router were to generate 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 deprecation of Type 0 routing header [RFC5095] may be valid here. To address such concerns, the mechanism described in this document includes several remedies: 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. o This document requires that an MO message must not cross the boundaries of the RPL routing domain where it originated. A router must not forward a received MO message further if the next hop belongs to a different RPL routing domain. Hence, any security problems associated with the mechanism would be limited to one RPL routing domain. 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 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 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 against some of the security concerns even if a compromised node inserts a malformed Address vector inside the MO message. + The measurement mechanism described in this document may potentially + be used by a rogue node to find out key information about the LLN, + e.g., the topological features of the LLN (such as the identity of + the key nodes in the topology) or the remaining energy levels + [RFC6551] in the LLN routers. This information can potentially be + used to attack the LLN. To protect against such misuse, this + document allows RPL routers implementing this mechanism to not + process MO messages (or process such messages selectively) based on a + local policy. Further, an LLN deployment may use Secure MO + Section 3.2 messages to invoke RPL-provided security mechanisms and + prevent misuse of the measurement mechanism by unauthorized nodes. + 9. IANA Considerations This document defines two new RPL messages: o "Measurement Object" (see Section 3.1), assigned a value TBD1 from the "RPL Control Codes" space [to be removed upon publication: 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 @@ -815,31 +1053,31 @@ 10. Acknowledgements Authors gratefully acknowledge the contributions of Matthias Philipp, Pascal Thubert, Richard Kelsey and Zach Shelby in the development of this document. 11. 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-15 + (work in progress), December 2012. + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 11.2. Informative 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-13 - (work in progress), June 2012. - [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation of Type 0 Routing Headers in IPv6", RFC 5095, December 2007. [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation Routing Requirements in Low-Power and Lossy Networks", RFC 5826, April 2010. [RFC5867] Martocci, J., De Mil, P., Riou, N., and W. Vermeylen, "Building Automation Routing Requirements in Low-Power and