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rfc:rfc5860

Internet Engineering Task Force (IETF) M. Vigoureux, Ed. Request for Comments: 5860 Alcatel-Lucent Category: Standards Track D. Ward, Ed. ISSN: 2070-1721 Juniper Networks

                                                         M. Betts, Ed.
                                           M. C. Betts Consulting Ltd.
                                                              May 2010
 Requirements for Operations, Administration, and Maintenance (OAM)
                     in MPLS Transport Networks

Abstract

 This document lists architectural and functional requirements for the
 Operations, Administration, and Maintenance of MPLS Transport
 Profile.  These requirements apply to pseudowires, Label Switched
 Paths, and Sections.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc5860.

Copyright Notice

 Copyright (c) 2010 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
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 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.

Vigoureux, et al. Standards Track [Page 1] RFC 5860 OAM Requirements for MPLS-TP May 2010

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1.  Scope of This Document . . . . . . . . . . . . . . . . . .  3
   1.2.  Requirements Language and Terminology  . . . . . . . . . .  4
 2.  OAM Requirements . . . . . . . . . . . . . . . . . . . . . . .  5
   2.1.  Architectural Requirements . . . . . . . . . . . . . . . .  6
     2.1.1.  Scope of OAM . . . . . . . . . . . . . . . . . . . . .  6
     2.1.2.  Independence . . . . . . . . . . . . . . . . . . . . .  6
     2.1.3.  Data Plane . . . . . . . . . . . . . . . . . . . . . .  7
     2.1.4.  OAM and IP Capabilities  . . . . . . . . . . . . . . .  7
     2.1.5.  Interoperability and Interworking  . . . . . . . . . .  8
     2.1.6.  Configuration  . . . . . . . . . . . . . . . . . . . .  8
   2.2.  Functional Requirements  . . . . . . . . . . . . . . . . .  9
     2.2.1.  General Requirements . . . . . . . . . . . . . . . . .  9
     2.2.2.  Continuity Checks  . . . . . . . . . . . . . . . . . . 10
     2.2.3.  Connectivity Verifications . . . . . . . . . . . . . . 10
     2.2.4.  Route Tracing  . . . . . . . . . . . . . . . . . . . . 11
     2.2.5.  Diagnostic Tests . . . . . . . . . . . . . . . . . . . 11
     2.2.6.  Lock Instruct  . . . . . . . . . . . . . . . . . . . . 11
     2.2.7.  Lock Reporting . . . . . . . . . . . . . . . . . . . . 12
     2.2.8.  Alarm Reporting  . . . . . . . . . . . . . . . . . . . 12
     2.2.9.  Remote Defect Indication . . . . . . . . . . . . . . . 13
     2.2.10. Client Failure Indication  . . . . . . . . . . . . . . 13
     2.2.11. Packet Loss Measurement  . . . . . . . . . . . . . . . 13
     2.2.12. Packet Delay Measurement . . . . . . . . . . . . . . . 14
 3.  Congestion Considerations  . . . . . . . . . . . . . . . . . . 15
 4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
 5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
 6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
   6.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
   6.2.  Informative References . . . . . . . . . . . . . . . . . . 16

Vigoureux, et al. Standards Track [Page 2] RFC 5860 OAM Requirements for MPLS-TP May 2010

1. Introduction

 In the context of MPLS Transport Profile (MPLS-TP, see [9] and [1]),
 the rationales for Operations, Administration, and Maintenance (OAM)
 are twofold as it can serve:
 o  as a network-oriented functionality, used by a transport network
    operator to monitor his network infrastructure and to implement
    internal mechanisms in order to enhance the general behavior and
    the level of performance of his network (e.g., protection
    mechanism in case of node or link failure).  As an example, fault
    localization is typically associated with this use case.
 o  as a service-oriented functionality, used by a transport service
    provider to monitor services offered to end customers in order to
    be able to react rapidly in case of a problem and to be able to
    verify some of the Service Level Agreement (SLA) parameters (e.g.,
    using performance monitoring) negotiated with the end customers.
    Note that a transport service could be provided over several
    networks or administrative domains that may not all be owned and
    managed by the same transport service provider.
 More generally, OAM is an important and fundamental functionality in
 transport networks as it contributes to:
 o  the reduction of operational complexity and costs, by allowing for
    efficient and automatic detection, localization, and handling and
    diagnosis of defects, as well as by minimizing service
    interruptions and operational repair times.
 o  the enhancement of network availability, by ensuring that defects
    (for example, those resulting in misdirected customer traffic) and
    faults are detected, diagnosed, and dealt with before a customer
    reports the problem.
 o  meeting service and performance objectives, as the OAM
    functionality allows for SLA verification in a multi-maintenance
    domain environment and allows for the determination of service
    degradation due, for example, to packet delay or packet loss.

1.1. Scope of This Document

 This document lists architectural and functional requirements for the
 OAM functionality of MPLS-TP.  These requirements apply to
 pseudowires (PWs), Label Switched Paths (LSPs), and Sections.
 These requirements are derived from the set of requirements specified
 by ITU-T and published in the ITU-T Supplement Y.Sup4 [10].

Vigoureux, et al. Standards Track [Page 3] RFC 5860 OAM Requirements for MPLS-TP May 2010

 By covering transport specificities, these requirements complement
 those identified in RFC 4377 [11]; yet, some requirements may be
 similar.
 This document only lists architectural and functional OAM
 requirements.  It does not detail the implications of their
 applicability to the various types (e.g., point-to-point, point-to-
 multipoint, unidirectional, bidirectional, etc.) of PWs, LSPs, and
 Sections.  Furthermore, this document does not provide requirements
 on how the protocol solution(s) should behave to achieve the
 functional objectives.  Please see [12] for further information.
 Note that the OAM functions identified in this document may be used
 for fault-management, performance-monitoring, and/or protection-
 switching applications.  For example, connectivity verification can
 be used for fault management by detecting failure conditions, but may
 also be used for performance monitoring through its contribution to
 the evaluation of performance metrics (e.g., unavailability time).
 Nevertheless, it is outside the scope of this document to specify
 which function should be used for which application.
 Note also that it is anticipated that implementers may wish to
 implement OAM message handling in hardware.  Although not a
 requirement, this fact could be taken as a design consideration.

1.2. Requirements Language and Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [2].
 Although this document is not a protocol specification, the use of
 this language clarifies the instructions to protocol designers
 producing solutions that satisfy the requirements set out in this
 document.
 In this document, we:
 o  refer to the inability of a function to perform a required action
    as a fault.  This does not include an inability due to preventive
    maintenance, lack of external resources, or planned actions.  See
    also ITU-T G.806 [3].
 o  refer to the situation in which the density of anomalies has
    reached a level where the ability to perform a required function
    has been interrupted as a defect.  See also ITU-T G.806 [3].

Vigoureux, et al. Standards Track [Page 4] RFC 5860 OAM Requirements for MPLS-TP May 2010

 o  refer to OAM actions that are carried out continuously or at least
    over long periods of time, permitting proactive reporting of fault
    and/or performance results as proactive OAM.
 o  refer to OAM actions that are initiated via manual intervention
    for a limited time to carry out troubleshooting as on-demand OAM.
 o  refer to a Label Edge Router (LER), for a given LSP or Section,
    and to a PW Terminating Provider Edge (T-PE), for a given PW, as
    an End Point.  Further, we refer to a Label Switching Router
    (LSR), for a given LSP, and to a PW Switching Provider Edge
    (S-PE), for a given PW, as an Intermediate Point.  This document
    does not make a distinction between End Points (e.g., source and
    destination) as it can be inferred from the context of the
    sentences.
 o  use the term "node" as a general reference to End Points and
    Intermediate Points.
 o  refer to both segment and concatenated segments as segments (see
    [1] for definitions relating to the term "segment" as well as for
    other definitions relating to MPLS-TP).
 o  refer to both single segment PWs and multi-segment PWs as PWs.
 o  refer to both bidirectional associated LSPs and bidirectional co-
    routed LSPs as bidirectional LSPs.

2. OAM Requirements

 This section lists the requirements by which the OAM functionality of
 MPLS-TP should abide.
 The requirements listed below may be met by one or more OAM
 protocols; the definition or selection of these protocols is outside
 the scope of this document.
 RFC 5654 [1] states (Requirement #2) that the MPLS-TP design, SHOULD
 as far as reasonably possible, reuse existing MPLS standards.  This
 general requirement applies to MPLS-TP OAM.  MPLS-TP OAM is defined
 in this document through a set of functional requirements.  These
 requirements will be met by protocol solutions defined in other
 documents.  The way in which those protocols are operated and the way
 in which a network operator can control and use the MPLS-TP OAM
 functions SHOULD be as similar as possible to the mechanisms and
 techniques used to operate OAM in other transport technologies.

Vigoureux, et al. Standards Track [Page 5] RFC 5860 OAM Requirements for MPLS-TP May 2010

2.1. Architectural Requirements

2.1.1. Scope of OAM

 The protocol solution(s) developed to meet the requirements
 identified in this document MUST at least be applicable to point-to-
 point bidirectional PWs, point-to-point co-routed bidirectional LSPs,
 and point-to-point bidirectional Sections.  Section 2.2 provides
 additional information with regard to the applicability to point-to-
 point associated bidirectional LSPs, point-to-point unidirectional
 LSPs, and point-to-multipoint LSPs.
 The service emulated by a PW may span multiple domains.  An LSP may
 also span multiple domains.  The protocol solution(s) MUST be
 applicable to end-to-end and to segments.  More generally, it MUST be
 possible to operate OAM functions on a per-domain basis and across
 multiple domains.
 Since LSPs may be stacked, the protocol solution(s) MUST be
 applicable on any LSP, regardless of the label stack depth.
 Furthermore, it MUST be possible to estimate OAM fault and
 performance metrics of a single PW or LSP segment or of an aggregate
 of PW or LSP segments.

2.1.2. Independence

 The protocol solution(s) SHOULD be independent of the underlying
 tunneling or point-to-point technology or transmission media.
 The protocol solution(s) SHOULD be independent of the service a PW
 may emulate.
 Any OAM function operated on a PW, LSP, or Section SHOULD be
 independent of the OAM function(s) operated on a different PW, LSP,
 or Section.  In other words, only the OAM functions operated on a
 given LSP (for example) should be used to achieve the OAM objectives
 for that LSP.
 The protocol solution(s) MUST support the capability to be
 concurrently and independently operated end-to-end and on segments.
 Therefore, any OAM function applied to segment(s) of a PW or LSP
 SHOULD be independent of the OAM function(s) operated on the end-to-
 end PW or LSP.  It SHOULD also be possible to distinguish an OAM
 packet running over a segment of a PW or LSP from another OAM packet
 running on the end-to-end PW or LSP.

Vigoureux, et al. Standards Track [Page 6] RFC 5860 OAM Requirements for MPLS-TP May 2010

 Furthermore, any OAM function applied to segment(s) of a PW or LSP
 SHOULD be independent of the OAM function(s) applied to other
 segment(s) of the same PW or LSP.
    Note: Independence should not be understood in terms of isolation
    as there can be interactions between OAM functions operated, for
    example, on two different LSPs.

2.1.3. Data Plane

 OAM functions operate in the data plane.  OAM packets MUST run in-
 band; that is, OAM packets for a specific PW, LSP, or Section MUST
 follow the exact same data path as user traffic of that PW, LSP, or
 Section.  This is often referred to as fate sharing.
 It MUST be possible to discriminate user traffic from OAM packets.
 This includes a means to differentiate OAM packets from user traffic
 as well as the capability to apply specific treatment to OAM packets,
 at the nodes processing these OAM packets.
 As part of the design of OAM protocol solution(s) for MPLS-TP, a
 mechanism for enabling the encapsulation and differentiation of OAM
 messages on a PW, LSP, or Section, MUST be provided.  Such mechanism
 SHOULD also support the encapsulation and differentiation of existing
 IP/MPLS and PW OAM messages.

2.1.4. OAM and IP Capabilities

 There are environments where IP capabilities are present in the data
 plane.  IP/MPLS environments are examples of such environments.
 There are also environments where IP capabilities may not be present
 in the data plane.  MPLS-TP environments are examples of environments
 where IP capabilities might or might not be present.
    Note: Presence or absence of IP capabilities is deployment
    scenario dependent.
 It MUST be possible to deploy the OAM functionality in any of these
 environments.  As a result, it MUST be possible to operate OAM
 functions with or without relying on IP capabilities, and it MUST be
 possible to choose to make use of IP capabilities when these are
 present.
 Furthermore, the mechanism required for enabling the encapsulation
 and differentiation of OAM messages (see Section 2.1.3) MUST support
 the capability to differentiate OAM messages of an OAM function

Vigoureux, et al. Standards Track [Page 7] RFC 5860 OAM Requirements for MPLS-TP May 2010

 operated by relying on IP capabilities (e.g., using encapsulation in
 an IP header) from OAM messages of an OAM function operated without
 relying on any IP capability.
 Note that IP capabilities include the capability to form a standard
 IP header, to encapsulate a payload in an IP header, to parse and
 analyze the fields of an IP header, and to take actions based on the
 content of these fields.
 For certain functions, OAM messages need to incorporate
 identification information (e.g., of source and/or destination
 nodes).  The protocol solution(s) MUST at least support
 identification information in the form of an IP addressing structure
 and MUST also be extensible to support additional identification
 schemes.

2.1.5. Interoperability and Interworking

 It is REQUIRED that OAM interoperability is achieved between distinct
 domains materializing the environments described in Section 2.1.4.
 It is also REQUIRED that the first two requirements of Section 2.1.4
 still hold and MUST still be met when interoperability is achieved.
 When MPLS-TP is run with IP routing and forwarding capabilities, it
 MUST be possible to operate any of the existing IP/MPLS and PW OAM
 protocols (e.g., LSP-Ping [4], MPLS-BFD [13], VCCV [5], and VCCV-BFD
 [14]).

2.1.6. Configuration

 OAM functions MUST operate and be configurable even in the absence of
 a control plane.  Conversely, it SHOULD be possible to configure as
 well as enable/disable the capability to operate OAM functions as
 part of connectivity management, and it SHOULD also be possible to
 configure as well as enable/disable the capability to operate OAM
 functions after connectivity has been established.
 In the latter case, the customer MUST NOT perceive service
 degradation as a result of OAM enabling/disabling.  Ideally, OAM
 enabling/disabling should take place without introducing any customer
 impairments (e.g., no customer packet losses).  Procedures aimed to
 prevent any traffic impairment MUST be defined for the enabling/
 disabling of OAM functions.
 Means for configuring OAM functions and for connectivity management
 are outside the scope of this document.

Vigoureux, et al. Standards Track [Page 8] RFC 5860 OAM Requirements for MPLS-TP May 2010

2.2. Functional Requirements

 Hereafter are listed the required functionalities composing the
 MPLS-TP OAM toolset.  The list may not be exhaustive and as such the
 OAM mechanisms developed in support of the identified requirements
 SHALL be extensible and thus SHALL NOT preclude the definition of
 additional OAM functionalities, in the future.
 The design of OAM mechanisms for MPLS-TP, MUST allow for the ability
 to support experimental OAM functions.  These functions MUST be
 disabled by default.
 The use of any OAM function MUST be optional and it MUST be possible
 to select the set of OAM function(s) to use on any PW, LSP, or
 Section.
 It is RECOMMENDED that any protocol solution, meeting one or more
 functional requirement(s), be the same for PWs, LSPs, and Sections.
 It is RECOMMENDED that any protocol solution, meeting one or more
 functional requirement(s), effectively provides a fully featured
 function; that is, a function that is applicable to all the cases
 identified for that functionality.  In that context, protocol
 solution(s) MUST state their applicability.
 Unless otherwise stated, the OAM functionalities MUST NOT rely on
 user traffic; that is, only OAM messages MUST be used to achieve the
 objectives.
 For the on-demand OAM functions, the result of which may vary
 depending on packet size, it SHOULD be possible to perform these
 functions using different packet sizes.

2.2.1. General Requirements

 If a defect or fault occurs on a PW, LSP, or Section, mechanisms MUST
 be provided to detect it, diagnose it, localize it, and notify the
 appropriate nodes.  Mechanisms SHOULD exist such that corrective
 actions can be taken.
 Furthermore, mechanisms MUST be available for a service provider to
 be aware of a fault or defect affecting the service(s) he provides,
 even if the fault or defect is located outside of his domain.

Vigoureux, et al. Standards Track [Page 9] RFC 5860 OAM Requirements for MPLS-TP May 2010

 Protocol solution(s) developed to meet these requirements may rely on
 information exchange.  Information exchange between various nodes
 involved in the operation of an OAM function SHOULD be reliable such
 that, for example, defects or faults are properly detected or that
 state changes are effectively known by the appropriate nodes.

2.2.2. Continuity Checks

 The MPLS-TP OAM toolset MUST provide a function to enable an End
 Point to monitor the liveness of a PW, LSP, or Section.
 This function SHOULD be performed between End Points of PWs, LSPs,
 and Sections.
 This function SHOULD be performed proactively.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.3. Connectivity Verifications

 The MPLS-TP OAM toolset MUST provide a function to enable an End
 Point to determine whether or not it is connected to specific End
 Point(s) by means of the expected PW, LSP, or Section.
 This function SHOULD be performed proactively between End Points of
 PWs, LSPs, and Sections.
 This function SHOULD be performed on-demand between End Points and
 Intermediate Points of PWs and LSPs, and between End Points of PWs,
 LSPs, and Sections.
 The protocol solution(s) developed to perform this function
 proactively MUST also apply to point-to-point associated
 bidirectional LSPs, point-to-point unidirectional LSPs, and point-to-
 multipoint LSPs.
 The protocol solution(s) developed to perform this function on-demand
 MAY also apply to point-to-point associated bidirectional LSPs, to
 point-to-point unidirectional LSPs, and point-to-multipoint LSPs in
 case a return path exists.

Vigoureux, et al. Standards Track [Page 10] RFC 5860 OAM Requirements for MPLS-TP May 2010

2.2.4. Route Tracing

 The MPLS-TP OAM toolset MUST provide functionality to enable an End
 Point to discover the Intermediate (if any) and End Point(s) along a
 PW, LSP, or Section, and more generally to trace the route of a PW,
 LSP, or Section.  The information collected MUST include identifiers
 related to the nodes and interfaces composing that route.
 This function SHOULD be performed on-demand.
 This function SHOULD be performed between End Points and Intermediate
 Points of PWs and LSPs, and between End Points of PWs, LSPs, and
 Sections.
 The protocol solution(s) developed to perform this function MAY also
 apply to point-to-point associated bidirectional LSPs, to point-to-
 point unidirectional LSPs, and point-to-multipoint LSPs in case a
 return path exists.

2.2.5. Diagnostic Tests

 The MPLS-TP OAM toolset MUST provide a function to enable conducting
 diagnostic tests on a PW, LSP, or Section.  An example of such a
 diagnostic test consists of performing a loop-back function at a node
 such that all OAM and data traffic are looped back to the originating
 End Point.  Another example of such diagnostic test consists in
 estimating the bandwidth of, e.g., an LSP.
 This function SHOULD be performed on-demand.
 This function SHOULD be performed between End Points and Intermediate
 Points of PWs and LSPs, and between End Points of PWs, LSPs, and
 Sections.
 The protocol solution(s) developed to perform this function MAY also
 apply to point-to-point associated bidirectional LSPs, to point-to-
 point unidirectional LSPs and point-to-multipoint LSPs, in case a
 return path exists.

2.2.6. Lock Instruct

 The MPLS-TP OAM toolset MUST provide functionality to enable an End
 Point of a PW, LSP, or Section to instruct its associated End
 Point(s) to lock the PW, LSP, or Section.  Note that lock corresponds
 to an administrative status in which it is expected that only test
 traffic, if any, and OAM (dedicated to the PW, LSP, or Section) can
 be mapped on that PW, LSP, or Section.

Vigoureux, et al. Standards Track [Page 11] RFC 5860 OAM Requirements for MPLS-TP May 2010

 This function SHOULD be performed on-demand.
 This function SHOULD be performed between End Points of PWs, LSPs,
 and Sections.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.7. Lock Reporting

 Based on the tunneling capabilities of MPLS, there are cases where
 Intermediate Point(s) of a PW or of an LSP coincide with End Point(s)
 of another LSP on which the former is mapped/tunneled.  Further, it
 may happen that the tunnel LSP is out of service as a result of a
 lock action on that tunnel LSP.  By means outside of the scope of
 this document, the Intermediate Point(s) of the PW or LSP may be
 aware of this condition.  The MPLS-TP OAM toolset MUST provide a
 function to enable an Intermediate Point of a PW or LSP to report, to
 an End Point of that same PW or LSP, a lock condition indirectly
 affecting that PW or LSP.
 This function SHOULD be performed proactively.
 This function SHOULD be performed between Intermediate Points and End
 Points of PWs and LSPs.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.8. Alarm Reporting

 Based on the tunneling capabilities of MPLS, there are cases where
 Intermediate Point(s) of a PW or of an LSP coincide with End Point(s)
 of another LSP on which the former is mapped/tunneled.  Further, it
 may happen that the tunnel LSP be out of service as a result of a
 fault on that tunnel LSP.  By means outside of the scope of this
 document, the Intermediate Point(s) of the PW or LSP may be aware of
 this condition.  The MPLS-TP OAM toolset MUST provide functionality
 to enable an Intermediate Point of a PW or LSP to report, to an End
 Point of that same PW or LSP, a fault or defect condition indirectly
 affecting that PW or LSP.
 This function SHOULD be performed proactively.
 This function SHOULD be performed between Intermediate Points and End
 Points of PWs and LSPs.

Vigoureux, et al. Standards Track [Page 12] RFC 5860 OAM Requirements for MPLS-TP May 2010

 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.9. Remote Defect Indication

 The MPLS-TP OAM toolset MUST provide a function to enable an End
 Point to report, to its associated End Point, a fault or defect
 condition that it detects on a PW, LSP, or Section for which they are
 the End Points.
 This function SHOULD be performed proactively.
 This function SHOULD be performed between End Points of PWs, LSPs,
 and Sections.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs and MAY also
 apply to point-to-point unidirectional LSPs and point-to-multipoint
 LSPs in case a return path exists.

2.2.10. Client Failure Indication

 The MPLS-TP OAM toolset MUST provide a function to enable the
 propagation, from edge to edge of an MPLS-TP network, of information
 pertaining to a client (i.e., external to the MPLS-TP network) defect
 or fault condition detected at an End Point of a PW or LSP, if the
 client layer OAM functionality does not provide an alarm
 notification/propagation functionality.
 This function SHOULD be performed proactively.
 This function SHOULD be performed between End Points of PWs and LSPs.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.11. Packet Loss Measurement

 The MPLS-TP OAM toolset MUST provide a function to enable the
 quantification of packet loss ratio over a PW, LSP, or Section.
 The loss of a packet is defined in RFC2680 [6] (see Section 2.4).
 This definition is used here.

Vigoureux, et al. Standards Track [Page 13] RFC 5860 OAM Requirements for MPLS-TP May 2010

 Packet-loss ratio is defined here to be the ratio of the number of
 user packets lost to the total number of user packets sent during a
 defined time interval.
 This function MAY either be performed proactively or on-demand.
 This function SHOULD be performed between End Points of PWs, LSPs,
 and Sections.
 It SHOULD be possible to rely on user traffic to perform this
 functionality.
 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs.

2.2.12. Packet Delay Measurement

 The MPLS-TP OAM toolset MUST provide a function to enable the
 quantification of the one-way, and if appropriate, the two-way, delay
 of a PW, LSP, or Section.
 o  The one-way delay is defined in [7] to be the time elapsed from
    the start of transmission of the first bit of a packet by an End
    Point until the reception of the last bit of that packet by the
    other End Point.
 o  The two-way delay is defined in [8] to be the time elapsed from
    the start of transmission of the first bit of a packet by an End
    Point until the reception of the last bit of that packet by the
    same End Point.
 Two-way delay may be quantified using data traffic loopback at the
 remote End Point of the PW, LSP, or Section (see Section 2.2.5).
 Accurate quantification of one-way delay may require clock
 synchronization, the means for which are outside the scope of this
 document.
 This function SHOULD be performed on-demand and MAY be performed
 proactively.
 This function SHOULD be performed between End Points of PWs, LSPs,
 and Sections.

Vigoureux, et al. Standards Track [Page 14] RFC 5860 OAM Requirements for MPLS-TP May 2010

 The protocol solution(s) developed to perform this function MUST also
 apply to point-to-point associated bidirectional LSPs, point-to-point
 unidirectional LSPs, and point-to-multipoint LSPs, but only to enable
 the quantification of the one-way delay.

3. Congestion Considerations

 A mechanism (e.g., rate limiting) MUST be provided to prevent OAM
 packets from causing congestion in the Packet Switched Network.

4. Security Considerations

 This document, in itself, does not imply any security consideration
 but OAM, as such, is subject to several security considerations.  OAM
 messages can reveal sensitive information such as passwords,
 performance data and details about, e.g., the network topology.
 The nature of OAM therefore suggests having some form of
 authentication, authorization, and encryption in place.  This will
 prevent unauthorized access to MPLS-TP equipment and it will prevent
 third parties from learning about sensitive information about the
 transport network.
 OAM systems (network management stations) SHOULD be designed such
 that OAM functions cannot be accessed without authorization.
 OAM protocol solutions MUST include the facility for OAM messages to
 authenticated to prove their origin and to make sure that they are
 destined for the receiving node.  The use of such facilities MUST be
 configurable.
 An OAM packet received over a PW, LSP, or Section MUST NOT be
 forwarded beyond the End Point of that PW, LSP, or Section, so as to
 avoid that the OAM packet leaves the current administrative domain.

5. Acknowledgements

 The editors gratefully acknowledge the contributions of Matthew
 Bocci, Italo Busi, Thomas Dietz, Annamaria Fulignoli, Huub van
 Helvoort, Enrique Hernandez-Valencia, Wataru Imajuku, Kam Lam, Marc
 Lasserre, Lieven Levrau, Han Li, Julien Meuric, Philippe Niger,
 Benjamin Niven-Jenkins, Jing Ruiquan, Nurit Sprecher, Yuji Tochio,
 Satoshi Ueno, and Yaacov Weingarten.
 The authors would like to thank all members of the teams (the Joint
 Working Team, the MPLS Interoperability Design Team in IETF, and the
 MPLS-TP Ad Hoc Group in ITU-T) involved in the definition and
 specification of MPLS-TP.

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6. References

6.1. Normative References

 [1]   Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
       S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,
       September 2009.
 [2]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.
 [3]   ITU-T Recommendation G.806, "Characteristics of transport
       equipment - Description methodology and generic functionality",
       2009.
 [4]   Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label
       Switched (MPLS) Data Plane Failures", RFC 4379, February 2006.
 [5]   Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit
       Connectivity Verification (VCCV): A Control Channel for
       Pseudowires", RFC 5085, December 2007.
 [6]   Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Packet
       Loss Metric for IPPM", RFC 2680, September 1999.
 [7]   Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay
       Metric for IPPM", RFC 2679, September 1999.
 [8]   Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay
       Metric for IPPM", RFC 2681, September 1999.

6.2. Informative References

 [9]   Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, L.,
       and L. Berger, "A Framework for MPLS in Transport Networks",
       Work in Progress, May 2010.
 [10]  ITU-T Supplement Y.Sup4, "ITU-T Y.1300-series: Supplement on
       transport requirements for T-MPLS OAM and considerations for
       the application of IETF MPLS technology", 2008.
 [11]  Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S.
       Matsushima, "Operations and Management (OAM) Requirements for
       Multi-Protocol Label Switched (MPLS) Networks", RFC 4377,
       February 2006.
 [12]  Busi, I., Ed., Niven-Jenkins, B., Ed., and D. Allan, Ed.,
       "MPLS-TP OAM Framework", Work in Progress, April 2010.

Vigoureux, et al. Standards Track [Page 16] RFC 5860 OAM Requirements for MPLS-TP May 2010

 [13]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, "BFD
       For MPLS LSPs", Work in Progress, June 2008.
 [14]  Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional
       Forwarding Detection (BFD) for the Pseudowire Virtual Circuit
       Connectivity Verification (VCCV)", Work in Progress, July 2009.

Authors' Addresses

 Martin Vigoureux (editor)
 Alcatel-Lucent
 Route de Villejust
 Nozay  91620
 France
 EMail: martin.vigoureux@alcatel-lucent.com
 David Ward (editor)
 Juniper Networks
 EMail: dward@juniper.net
 Malcolm Betts (editor)
 M. C. Betts Consulting Ltd.
 EMail: malcolm.betts@rogers.com

Vigoureux, et al. Standards Track [Page 17]

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