





Internet Engineering Task Force (IETF)                            K. Lam
Request for Comments: 5951                                Alcatel-Lucent
Category: Standards Track                                   S. Mansfield
ISSN: 2070-1721                                                  E. Gray
                                                                Ericsson
                                                          September 2010


   Network Management Requirements for MPLS-based Transport Networks

Abstract

   This document specifies the requirements for the management of
   equipment used in networks supporting an MPLS Transport Profile
   (MPLS-TP).  The requirements are defined for specification of
   network management aspects of protocol mechanisms and procedures
   that constitute the building blocks out of which the MPLS
   Transport Profile is constructed.  That is, these requirements
   indicate what management capabilities need to be available in
   MPLS for use in managing the MPLS-TP.  This document is intended
   to identify essential network management capabilities, not to
   specify what functions any particular MPLS implementation
   supports.

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/rfc5951.













Lam, et al.                  Standards Track                    [Page 1]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


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.





































Lam, et al.                  Standards Track                    [Page 2]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


Table of Contents

   1. Introduction ....................................................4
      1.1. Terminology ................................................5
   2. Management Interface Requirements ...............................7
   3. Management Communication Channel (MCC) Requirements .............7
   4. Management Communication Network (MCN) Requirements .............7
   5. Fault Management Requirements ...................................9
      5.1. Supervision Function .......................................9
      5.2. Validation Function .......................................10
      5.3. Alarm Handling Function ...................................11
           5.3.1. Alarm Severity Assignment ..........................11
           5.3.2. Alarm Suppression ..................................11
           5.3.3. Alarm Reporting ....................................11
           5.3.4. Alarm Reporting Control ............................12
   6. Configuration Management Requirements ..........................12
      6.1. System Configuration ......................................12
      6.2. Control Plane Configuration ...............................13
      6.3. Path Configuration ........................................13
      6.4. Protection Configuration ..................................14
      6.5. OAM Configuration .........................................14
   7. Performance Management Requirements ............................15
      7.1. Path Characterization Performance Metrics .................15
      7.2. Performance Measurement Instrumentation ...................16
           7.2.1. Measurement Frequency ..............................16
           7.2.2. Measurement Scope ..................................17
   8. Security Management Requirements ...............................17
      8.1. Management Communication Channel Security .................17
      8.2. Signaling Communication Channel Security ..................18
      8.3. Distributed Denial of Service .............................18
   9. Security Considerations ........................................19
   10. Acknowledgments ...............................................19
   11. References ....................................................19
      11.1. Normative References .....................................19
      12.2. Informative References ...................................20
   Appendix A.  Communication Channel (CCh) Examples..................22
   Contributor's Address .............................................24














Lam, et al.                  Standards Track                    [Page 3]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


1.  Introduction

   This document specifies the requirements for the management of
   equipment used in networks supporting an MPLS Transport Profile
   (MPLS-TP).  The requirements are defined for specification of network
   management aspects of protocol mechanisms and procedures that
   constitute the building blocks out of which the MPLS Transport
   Profile is constructed.  That is, these requirements indicate what
   management capabilities need to be available in MPLS for use in
   managing the MPLS-TP.  This document is intended to identify
   essential network management capabilities, not to specify what
   functions any particular MPLS implementation supports.

   This document also leverages management requirements specified in
   ITU-T G.7710/Y.1701 [1] and RFC 4377 [2], and attempts to comply with
   the guidelines defined in RFC 5706 [15].

   ITU-T G.7710/Y.1701 defines generic management requirements for
   transport networks.  RFC 4377 specifies the operations and management
   requirements, including operations-and-management-related network
   management requirements, for MPLS networks.

   This document is a product of a joint ITU-T and IETF effort to
   include an MPLS Transport Profile (MPLS-TP) within the IETF MPLS and
   Pseudowire Emulation Edge-to-Edge (PWE3) architectures to support
   capabilities and functionality of a transport network as defined by
   the ITU-T.

   The requirements in this document derive from two sources:

   1) MPLS and PWE3 architectures as defined by the IETF, and

   2) packet transport networks as defined by the ITU-T.

   Requirements for management of equipment in MPLS-TP networks are
   defined herein.  Related functions of MPLS and PWE3 are defined
   elsewhere (and are out of scope in this document).

   This document expands on the requirements in ITU-T G.7710/Y.1701 [1]
   and RFC 4377 [2] to cover fault, configuration, performance, and
   security management for MPLS-TP networks, and the requirements for
   object and information models needed to manage MPLS-TP networks and
   network elements.

   In writing this document, the authors assume the reader is familiar
   with RFCs 5921 [8] and 5950 [9].





Lam, et al.                  Standards Track                    [Page 4]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


1.1.  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 [5].
   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.

   Anomaly: The smallest discrepancy that can be observed between actual
   and desired characteristics of an item.  The occurrence of a single
   anomaly does not constitute an interruption in ability to perform a
   required function.  Anomalies are used as the input for the
   Performance Monitoring (PM) process and for detection of defects
   (from [21], Section 3.7).

   Communication Channel (CCh): A logical channel between network
   elements (NEs) that can be used (for example) for management or
   control plane applications.  The physical channel supporting the CCh
   is technology specific.  See Appendix A.

   Data Communication Network (DCN): A network that supports Layer 1
   (physical layer), Layer 2 (data-link layer), and Layer 3 (network
   layer) functionality for distributed management communications
   related to the management plane, for distributed signaling
   communications related to the control plane, and other operations
   communications (e.g., order-wire/voice communications, software
   downloads, etc.).

   Defect: The density of anomalies has reached a level where the
   ability to perform a required function has been interrupted.  Defects
   are used as input for performance monitoring, the control of
   consequent actions, and the determination of fault cause (from [21],
   Section 3.24).

   Failure: The fault cause persisted long enough to consider the
   ability of an item to perform a required function to be terminated.
   The item may be considered as failed; a fault has now been detected
   (from [21], Section 3.25).

   Fault: A fault is the inability of a function to perform a required
   action.  This does not include an inability due to preventive
   maintenance, lack of external resources, or planned actions (from
   [21], Section 3.26).






Lam, et al.                  Standards Track                    [Page 5]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   Fault Cause: A single disturbance or fault may lead to the detection
   of multiple defects.  A fault cause is the result of a correlation
   process that is intended to identify the defect that is
   representative of the disturbance or fault that is causing the
   problem (from [21], Section 3.27).

   Fault Cause Indication (FCI): An indication of a fault cause.

   Management Communication Channel (MCC): A CCh dedicated for
   management plane communications.

   Management Communication Network (MCN): A DCN supporting management
   plane communication is referred to as a Management Communication
   Network (MCN).

   MPLS-TP NE: A network element (NE) that supports the functions of
   MPLS necessary to participate in an MPLS-TP based transport service.
   See RFC 5645 [7] for further information on functionality required to
   support MPLS-TP.

   MPLS-TP network: a network in which MPLS-TP NEs are deployed.

   Operations, Administration and Maintenance (OAM), On-Demand and
   Proactive: One feature of OAM that is largely a management issue is
   control of OAM; on-demand and proactive are modes of OAM mechanism
   operation defined in (for example) Y.1731 ([22] - Sections 3.45 and
   3.44, respectively) as:

   o  On-demand OAM - OAM actions that are initiated via manual
      intervention for a limited time to carry out diagnostics.
      On-demand OAM can result in singular or periodic OAM actions
      during the diagnostic time interval.

   o  Proactive OAM - OAM actions that are carried on continuously to
      permit timely reporting of fault and/or performance status.

   (Note that it is possible for specific OAM mechanisms to only have a
   sensible use in either on-demand or proactive mode.)

   Operations System (OS): A system that performs the functions that
   support processing of information related to operations,
   administration, maintenance, and provisioning (OAM&P) for the
   networks, including surveillance and testing functions to support
   customer access maintenance.







Lam, et al.                  Standards Track                    [Page 6]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   Signaling Communication Channel (SCC): A CCh dedicated for control
   plane communications.  The SCC can be used for GMPLS/ASON signaling
   and/or other control plane messages (e.g., routing messages).

   Signaling Communication Network (SCN): A DCN supporting control plane
   communication is referred to as a Signaling Communication Network
   (SCN).

2.  Management Interface Requirements

   This document does not specify a preferred management interface
   protocol to be used as the standard protocol for managing MPLS-TP
   networks.  Managing an end-to-end connection across multiple operator
   domains where one domain is managed (for example) via NETCONF [16] or
   SNMP [17], and another domain via CORBA [18], is allowed.

   1) For the management interface to the management system, an MPLS-TP
      NE MAY actively support more than one management protocol in any
      given deployment.

   For example, an operator can use one protocol for configuration of an
   MPLS-TP NE and another for monitoring.  The protocols to be supported
   are at the discretion of the operator.

3.  Management Communication Channel (MCC) Requirements

   1) Specifications SHOULD define support for management connectivity
      with remote MPLS-TP domains and NEs, as well as with termination
      points located in NEs under the control of a third party network
      operator.  See ITU-T G.8601 [23] for example scenarios in multi-
      carrier, multi-transport technology environments.

   2) For management purposes, every MPLS-TP NE MUST connect to an OS.
      The connection MAY be direct (e.g., via a software, hardware, or
      proprietary protocol connection) or indirect (via another MPLS-TP
      NE).  In this document, any management connection that is not via
      another MPLS-TP NE is a direct management connection.  When an
      MPLS-TP NE is connected indirectly to an OS, an MCC MUST be
      supported between that MPLS-TP NE and any MPLS-TP NE(s) used to
      provide the connection to an OS.

4.  Management Communication Network (MCN) Requirements

   Entities of the MPLS-TP management plane communicate via a DCN, or
   more specifically via the MCN.  The MCN connects management systems
   with management systems, management systems with MPLS-TP NEs, and (in
   the indirect connectivity case discussed in section 3) MPLS-TP NEs
   with MPLS-TP NEs.



Lam, et al.                  Standards Track                    [Page 7]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   RFC 5586 [14] defines a Generic Associated Channel (G-ACh) to enable
   the realization of a communication channel (CCh) between adjacent
   MPLS-TP NEs for management and control.  RFC 5718 [10] describes how
   the G-ACh can be used to provide infrastructure that forms part of
   the MCN and SCN.  It also explains how MCN and SCN messages are
   encapsulated, carried on the G-ACh, and decapsulated for delivery to
   management or signaling/routing control plane components on a label
   switching router (LSR).

   Section 7 of ITU-T G.7712/Y.1703 [6] describes the transport DCN
   architecture and requirements as follows:

   1) The MPLS-TP MCN MUST support the requirements for:

      a) CCh access functions specified in Section 7.1.1;

      b) MPLS-TP SCC data-link layer termination functions specified in
         Section 7.1.2.3;

      c) MPLS-TP MCC data-link layer termination functions specified in
         Section 7.1.2.4;

      d) Network layer PDU into CCh data-link frame encapsulation
         functions specified in Section 7.1.3;

      e) Network layer PDU forwarding (Section 7.1.6), interworking
         (Section 7.1.7), and encapsulation (Section 7.1.8) functions,
         as well as tunneling (Section 7.1.9) and routing (Section
         7.1.10) functions.

   As a practical matter, MCN connections will typically have addresses.
   See the section on Identifiers in RFC 5921 [8] for further
   information.

   In order to have the MCN operate properly, a number of management
   functions for the MCN are needed, including:

   o  Retrieval of DCN network parameters to ensure compatible
      functioning, e.g., packet size, timeouts, quality of service,
      window size, etc.;

   o  Establishment of message routing between DCN nodes;

   o  Management of DCN network addresses;

   o  Retrieval of operational status of the DCN at a given node;





Lam, et al.                  Standards Track                    [Page 8]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   o  Capability to enable/disable access by an NE to the DCN.  Note
      that this is to allow the isolation of a malfunctioning NE to keep
      it from impacting the rest of the network.

5.  Fault Management Requirements

   The Fault Management functions within an MPLS-TP NE enable the
   supervision, detection, validation, isolation, correction, and
   reporting of abnormal operation of the MPLS-TP network and its
   environment.

5.1.  Supervision Function

   The supervision function analyzes the actual occurrence of a
   disturbance or fault for the purpose of providing an appropriate
   indication of performance and/or detected fault condition to
   maintenance personnel and operations systems.

   1) The MPLS-TP NE MUST support supervision of the OAM mechanisms that
      are deployed for supporting the OAM requirements defined in RFC
      5860 [3].

   2) The MPLS-TP NE MUST support the following data-plane forwarding
      path supervision functions:

      a) Supervision of loop-checking functions used to detect loops in
         the data-plane forwarding path (which result in non-delivery of
         traffic, wasting of forwarding resources, and unintended self-
         replication of traffic);

      b) Supervision of failure detection;

   3) The MPLS-TP NE MUST support the capability to configure data-plane
      forwarding path related supervision mechanisms to perform
      on-demand or proactively.

   4) The MPLS-TP NE MUST support supervision for software processing --
      e.g., processing faults, storage capacity, version mismatch,
      corrupted data, and out of memory problems, etc.

   5) The MPLS-TP NE MUST support hardware-related supervision for
      interchangeable and non-interchangeable unit, cable, and power
      problems.

   6) The MPLS-TP NE SHOULD support environment-related supervision for
      temperature, humidity, etc.





Lam, et al.                  Standards Track                    [Page 9]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


5.2.  Validation Function

   Validation is the process of integrating Fault Cause indications into
   Failures.  A Fault Cause Indication (FCI) indicates a limited
   interruption of the required transport function.  A Fault Cause is
   not reported to maintenance personnel because it might exist only for
   a very short period of time.  Note that some of these events are
   summed up in the Performance Monitoring process (see Section 7), and
   when this sum exceeds a configured value, a threshold crossing alert
   (report) can be generated.

   When the Fault Cause lasts long enough, an inability to perform the
   required transport function arises.  This failure condition is
   subject to reporting to maintenance personnel and/or an OS because
   corrective action might be required.  Conversely, when the Fault
   Cause ceases after a certain time, clearing of the Failure condition
   is also subject to reporting.

   1) The MPLS-TP NE MUST perform persistency checks on fault causes
      before it declares a fault cause a failure.

   2) The MPLS-TP NE SHOULD provide a configuration capability for
      control parameters associated with performing the persistency
      checks described above.

   3) An MPLS-TP NE MAY provide configuration parameters to control
      reporting and clearing of failure conditions.

   4) A data-plane forwarding path failure MUST be declared if the fault
      cause persists continuously for a configurable time (Time-D).  The
      failure MUST be cleared if the fault cause is absent continuously
      for a configurable time (Time-C).

   Note: As an example, the default time values might be as follows:

      Time-D = 2.5 +/- 0.5 seconds

      Time-C = 10 +/- 0.5 seconds

   These time values are as defined in G.7710 [1].

   5) MIBs - or other object management semantics specifications -
      defined to enable configuration of these timers SHOULD explicitly
      provide default values and MAY provide guidelines on ranges and
      value determination methods for scenarios where the default value
      chosen might be inadequate.  In addition, such specifications
      SHOULD define the level of granularity at which tables of these
      values are to be defined.



Lam, et al.                  Standards Track                   [Page 10]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   6) Implementations MUST provide the ability to configure the
      preceding set of timers and SHOULD provide default values to
      enable rapid configuration.  Suitable default values, timer
      ranges, and level of granularity are out of scope in this document
      and form part of the specification of fault management details.
      Timers SHOULD be configurable per NE for broad categories (for
      example, defects and/or fault causes), and MAY be configurable
      per-interface on an NE and/or per individual defect/fault cause.

   7) The failure declaration and clearing MUST be time stamped.  The
      time-stamp MUST indicate the time at which the fault cause is
      activated at the input of the fault cause persistency (i.e.,
      defect-to-failure integration) function, and the time at which the
      fault cause is deactivated at the input of the fault cause
      persistency function.

5.3.  Alarm Handling Function

5.3.1.  Alarm Severity Assignment

   Failures can be categorized to indicate the severity or urgency of
   the fault.

   1) An MPLS-TP NE SHOULD support the ability to assign severity (e.g.,
      Critical, Major, Minor, Warning) to alarm conditions via
      configuration.

   See G.7710 [1], Section 7.2.2 for more detail on alarm severity
   assignment.  For additional discussion of Alarm Severity management,
   see discussion of alarm severity in RFC 3877 [11].

5.3.2.  Alarm Suppression

   Alarms can be generated from many sources, including OAM, device
   status, etc.

   1) An MPLS-TP NE MUST support suppression of alarms based on
      configuration.

5.3.3.  Alarm Reporting

   Alarm Reporting is concerned with the reporting of relevant events
   and conditions, which occur in the network (including the NE,
   incoming signal, and external environment).

   Local reporting is concerned with automatic alarming by means of
   audible and visual indicators near the failed equipment.




Lam, et al.                  Standards Track                   [Page 11]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   1) An MPLS-TP NE MUST support local reporting of alarms.

   2) The MPLS-TP NE MUST support reporting of alarms to an OS.  These
      reports are either autonomous reports (notifications) or reports
      on request by maintenance personnel.  The MPLS-TP NE SHOULD report
      local (environmental) alarms to a network management system.

   3) An MPLS-TP NE supporting one or more other networking technologies
      (e.g., Ethernet, SDH/SONET, MPLS) over MPLS-TP MUST be capable of
      translating MPLS-TP defects into failure conditions that are
      meaningful to the client layer, as described in RFC 4377 [2],
      Section 4.7.

5.3.4.  Alarm Reporting Control

   Alarm Reporting Control (ARC) supports an automatic in-service
   provisioning capability.  Alarm reporting can be turned off on a per-
   managed entity basis (e.g., LSP) to allow sufficient time for
   customer service testing and other maintenance activities in an
   "alarm free" state.  Once a managed entity is ready, alarm reporting
   is automatically turned on.

   1) An MPLS-TP NE SHOULD support the Alarm Reporting Control function
      for controlling the reporting of alarm conditions.

   See G.7710 [1] (Section 7.1.3.2) and RFC 3878 [24] for more
   information about ARC.

6.  Configuration Management Requirements

   Configuration Management provides functions to identify, collect data
   from, provide data to, and control NEs.  Specific configuration tasks
   requiring network management support include hardware and software
   configuration, configuration of NEs to support transport paths
   (including required working and protection paths), and configuration
   of required path integrity/connectivity and performance monitoring
   (i.e., OAM).

6.1.  System Configuration

   1) The MPLS-TP NE MUST support the configuration requirements
      specified in G.7710 [1], Section 8.1 for hardware.

   2) The MPLS-TP NE MUST support the configuration requirements
      specified in G.7710 [1], Section 8.2 for software.






Lam, et al.                  Standards Track                   [Page 12]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   3) The MPLS-TP NE MUST support the configuration requirements
      specified in G.7710 [1], Section 8.13.2.1 for local real-time
      clock functions.

   4) The MPLS-TP NE MUST support the configuration requirements
      specified in G.7710 [1], Section 8.13.2.2 for local real-time
      clock alignment with external time reference.

   5) The MPLS-TP NE MUST support the configuration requirements
      specified in G.7710 [1], Section 8.13.2.3 for performance
      monitoring of the clock function.

6.2.  Control Plane Configuration

   1) If a control plane is supported in an implementation of MPLS-TP,
      the MPLS-TP NE MUST support the configuration of MPLS-TP control
      plane functions by the management plane.  Further detailed
      requirements will be provided along with progress in defining the
      MPLS-TP control plane in appropriate specifications.

6.3.  Path Configuration

   1) In addition to the requirement to support static provisioning of
      transport paths (defined in RFC 5645 [7], Section 2.1 -- General
      Requirements, requirement 18), an MPLS-TP NE MUST support the
      configuration of required path performance characteristic
      thresholds (e.g., Loss Measurement <LM>, Delay Measurement <DM>
      thresholds) necessary to support performance monitoring of the
      MPLS-TP service(s).

   2) In order to accomplish this, an MPLS-TP NE MUST support
      configuration of LSP information (such as an LSP identifier of
      some kind) and/or any other information needed to retrieve LSP
      status information, performance attributes, etc.

   3) If a control plane is supported, and that control plane includes
      support for control-plane/management-plane hand-off for LSP
      setup/maintenance, the MPLS-TP NE MUST support management of the
      hand-off of Path control.  For example, see RFCs 5943 [19] and
      5852 [20].

   4) Further detailed requirements SHALL be provided along with
      progress in defining the MPLS-TP control plane in appropriate
      specifications.







Lam, et al.                  Standards Track                   [Page 13]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   5) If MPLS-TP transport paths cannot be statically provisioned using
      MPLS LSP and pseudowire management tools (either already defined
      in standards or under development), further management
      specifications MUST be provided as needed.

6.4.  Protection Configuration

   1) The MPLS-TP NE MUST support configuration of required path
      protection information as follows:

      o  designate specifically identified LSPs as working or protecting
         LSPs;

      o  define associations of working and protecting paths;

      o  operate/release manual protection switching;

      o  operate/release force protection switching;

      o  operate/release protection lockout;

      o  set/retrieve Automatic Protection Switching (APS) parameters,
         including

         o  Wait to Restore time,

         o  Protection Switching threshold information.

6.5.  OAM Configuration

   1) The MPLS-TP NE MUST support configuration of the OAM entities and
      functions specified in RFC 5860 [3].

   2) The MPLS-TP NE MUST support the capability to choose which OAM
      functions are enabled.

   3) For enabled OAM functions, the MPLS-TP NE MUST support the ability
      to associate OAM functions with specific maintenance entities.

   4) The MPLS-TP NE MUST support the capability to configure the OAM
      entities/functions as part of LSP setup and tear-down, including
      co-routed bidirectional point-to-point, associated bidirectional
      point-to-point, and uni-directional (both point-to-point and
      point-to-multipoint) connections.

   5) The MPLS-TP NE MUST support the configuration of maintenance
      entity identifiers (e.g., MEP ID and MIP ID) for the purpose of
      LSP connectivity checking.



Lam, et al.                  Standards Track                   [Page 14]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   6) The MPLS-TP NE MUST support configuration of OAM parameters to
      meet their specific operational requirements, such as

      a) one-time on-demand immediately or

      b) one-time on-demand pre-scheduled or

      c) on-demand periodically based on a specified schedule or

      d) proactive on-going.

   7) The MPLS-TP NE MUST support the enabling/disabling of the
      connectivity check processing.  The connectivity check process of
      the MPLS-TP NE MUST support provisioning of the identifiers to be
      transmitted and the expected identifiers.

7.  Performance Management Requirements

   Performance Management provides functions for the purpose of
   maintenance, bring-into-service, quality of service, and statistics
   gathering.

   This information could be used, for example, to compare behavior of
   the equipment, MPLS-TP NE, or network at different moments in time to
   evaluate changes in network performance.

   ITU-T Recommendation G.7710 [1] provides transport performance
   monitoring requirements for packet-switched and circuit-switched
   transport networks with the objective of providing a coherent and
   consistent interpretation of the network behavior in a multi-
   technology environment.  The performance management requirements
   specified in this document are driven by such an objective.

7.1.  Path Characterization Performance Metrics

   1) It MUST be possible to determine when an MPLS-TP-based transport
      service is available and when it is unavailable.

   From a performance perspective, a service is unavailable if there is
   an indication that performance has degraded to the extent that a
   configurable performance threshold has been crossed and the
   degradation persists long enough (i.e., the indication persists for
   some amount of time, which is either configurable or well-known) to
   be certain it is not a measurement anomaly.

   Methods, mechanisms, and algorithms for exactly how unavailability is
   to be determined -- based on collection of raw performance data --
   are out of scope for this document.



Lam, et al.                  Standards Track                   [Page 15]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   2) The MPLS-TP NE MUST support collection and reporting of raw
      performance data that MAY be used in determining the
      unavailability of a transport service.

   3) MPLS-TP MUST support the determination of the unavailability of
      the transport service.  The result of this determination MUST be
      available via the MPLS-TP NE (at service termination points), and
      determination of unavailability MAY be supported by the MPLS-TP NE
      directly.  To support this requirement, the MPLS-TP NE management
      information model MUST include objects corresponding to the
      availability-state of services.

   Transport network unavailability is based on Severely Errored Seconds
   (SES) and Unavailable Seconds (UAS).  The ITU-T is establishing
   definitions of unavailability that are generically applicable to
   packet transport technologies, including MPLS-TP, based on SES and
   UAS.  Note that SES and UAS are already defined for Ethernet
   transport networks in ITU-T Recommendation Y.1563 [25].

   4) The MPLS-TP NE MUST support collection of loss measurement (LM)
      statistics.

   5) The MPLS-TP NE MUST support collection of delay measurement (DM)
      statistics.

   6) The MPLS-TP NE MUST support reporting of performance degradation
      via fault management for corrective actions.

   "Reporting" in this context could mean:

      o  reporting to an autonomous protection component to trigger
         protection switching,

      o  reporting via a craft interface to allow replacement of a
         faulty component (or similar manual intervention),

      o  etc.

   7) The MPLS-TP NE MUST support reporting of performance statistics on
      request from a management system.

7.2.  Performance Measurement Instrumentation

7.2.1.  Measurement Frequency

   1) For performance measurement mechanisms that support both proactive
      and on-demand modes, the MPLS-TP NE MUST support the capability to
      be configured to operate on-demand or proactively.



Lam, et al.                  Standards Track                   [Page 16]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


7.2.2.  Measurement Scope

   On measurement of packet loss and loss ratio:

   1) For bidirectional (both co-routed and associated) point-to-point
      (P2P) connections

      a) on-demand measurement of single-ended packet loss and loss
         ratio measurement is REQUIRED;

      b) proactive measurement of packet loss and loss ratio measurement
         for each direction is REQUIRED.

   2) For unidirectional (P2P and point-to-multipoint (P2MP))
      connection, proactive measurement of packet loss and loss ratio is
      REQUIRED.

   On Delay measurement:

   3) For a unidirectional (P2P and P2MP) connection, on-demand
      measurement of delay measurement is REQUIRED.

   4) For a co-routed bidirectional (P2P) connection, on-demand
      measurement of one-way and two-way delay is REQUIRED.

   5) For an associated bidirectional (P2P) connection, on-demand
      measurement of one-way delay is REQUIRED.

8.  Security Management Requirements

   1) The MPLS-TP NE MUST support secure management and control planes.

8.1.  Management Communication Channel Security

   1) Secure communication channels MUST be supported for all network
      traffic and protocols used to support management functions.  This
      MUST include, at least, protocols used for configuration,
      monitoring, configuration backup, logging, time synchronization,
      authentication, and routing.

   2) The MCC MUST support application protocols that provide
      confidentiality and data-integrity protection.

   3) The MPLS-TP NE MUST support the following:

      a) Use of open cryptographic algorithms (see RFC 3871 [4]).





Lam, et al.                  Standards Track                   [Page 17]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


      b) Authentication - allow management connectivity only from
         authenticated entities.

      c) Authorization - allow management activity originated by an
         authorized entity, using (for example) an Access Control List
         (ACL).

      d) Port Access Control - allow management activity received on an
         authorized (management) port.

8.2.  Signaling Communication Channel Security

   Security requirements for the SCC are driven by considerations
   similar to MCC requirements described in Section 8.1.

   Security Requirements for the control plane are out of scope for this
   document and are expected to be defined in the appropriate control
   plane specifications.

   1) Management of control plane security MUST be defined in the
      appropriate control plane specifications.

8.3.  Distributed Denial of Service

   A denial-of-service (DoS) attack is an attack that tries to prevent a
   target from performing an assigned task, or providing its intended
   service(s), through any means.  A Distributed DoS (DDoS) can multiply
   attack severity (possibly by an arbitrary amount) by using multiple
   (potentially compromised) systems to act as topologically (and
   potentially geographically) distributed attack sources.  It is
   possible to lessen the impact and potential for DoS and DDoS by using
   secure protocols, turning off unnecessary processes, logging and
   monitoring, and ingress filtering.  RFC 4732 [26] provides background
   on DoS in the context of the Internet.

   1) An MPLS-TP NE MUST support secure management protocols and SHOULD
      do so in a manner that reduces potential impact of a DoS attack.

   2) An MPLS-TP NE SHOULD support additional mechanisms that mitigate a
      DoS (or DDoS) attack against the management component while
      allowing the NE to continue to meet its primary functions.










Lam, et al.                  Standards Track                   [Page 18]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


9.  Security Considerations

   Section 8 includes a set of security requirements that apply to MPLS-
   TP network management.

   1) Solutions MUST provide mechanisms to prevent unauthorized and/or
      unauthenticated access to management capabilities and private
      information by network elements, systems, or users.

   Performance of diagnostic functions and path characterization
   involves extracting a significant amount of information about network
   construction that the network operator might consider private.

10.  Acknowledgments

   The authors/editors gratefully acknowledge the thoughtful review,
   comments, and explanations provided by Adrian Farrel, Alexander
   Vainshtein, Andrea Maria Mazzini, Ben Niven-Jenkins, Bernd Zeuner,
   Dan Romascanu, Daniele Ceccarelli, Diego Caviglia, Dieter Beller, He
   Jia, Leo Xiao, Maarten Vissers, Neil Harrison, Rolf Winter, Yoav
   Cohen, and Yu Liang.

11.  References

11.1.  Normative References

   [1]   ITU-T Recommendation G.7710/Y.1701, "Common equipment
         management function requirements", July, 2007.

   [2]   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.

   [3]   Vigoureux, M., Ed., Ward, D., Ed., and M. Betts, Ed.,
         "Requirements for Operations, Administration, and Maintenance
         (OAM) in MPLS Transport Networks", RFC 5860, May 2010.

   [4]   Jones, G., Ed., "Operational Security Requirements for Large
         Internet Service Provider (ISP) IP Network Infrastructure", RFC
         3871, September 2004.

   [5]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [6]   ITU-T Recommendation G.7712/Y.1703, "Architecture and
         specification of data communication network", June 2008.




Lam, et al.                  Standards Track                   [Page 19]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   [7]   Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
         Sprecher, N., and S. Ueno, "Requirements of an MPLS Transport
         Profile", RFC 5654, September 2009.

   [8]   Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, L.,
         and L. Berger, "A Framework for MPLS in Transport Networks",
         RFC 5921, July 2010.

   [9]   Mansfield, S. Ed., Gray, E., Ed., and K. Lam, Ed., "Network
         Management Framework for MPLS-based Transport Networks", RFC
         5950, September 2010.

12.2.  Informative References

   [10]  Beller, D. and A. Farrel, "An In-Band Data Communication
         Network For the MPLS Transport Profile", RFC 5718, January
         2010.

   [11]  Chisholm, S. and D. Romascanu, "Alarm Management Information
         Base (MIB)", RFC 3877, September 2004.

   [12]  ITU-T Recommendation M.20, "Maintenance philosophy for
         telecommunication networks", October 1992.

   [13]  Telcordia, "Network Maintenance: Network Element and Transport
         Surveillance Messages" (GR-833-CORE), Issue 5, August 2004.

   [14]  Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., "MPLS
         Generic Associated Channel", RFC 5586, June 2009.

   [15]  Harrington, D., "Guidelines for Considering Operations and
         Management of New Protocols and Protocol Extensions", RFC 5706,
         November 2009.

   [16]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and
         A. Bierman, Ed., "Network Configuration Protocol (NETCONF)",
         Work in Progress, July 2010.

   [17]  Presuhn, R., Ed., "Version 2 of the Protocol Operations for the
         Simple Network Management Protocol (SNMP)", STD 62, RFC 3416,
         December 2002.

   [18]  OMG Document formal/04-03-12, "The Common Object Request
         Broker: Architecture and Specification", Revision 3.0.3.  March
         12, 2004.






Lam, et al.                  Standards Track                   [Page 20]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   [19]  Caviglia, D., Bramanti, D., Li, D., and D. McDysan,
         "Requirements for the Conversion between Permanent Connections
         and Switched Connections in a Generalized Multiprotocol Label
         Switching (GMPLS) Network", RFC 5493, April 2009.

   [20]  Caviglia, D., Ceccarelli, D., Bramanti, D., Li, D., and S.
         Bardalai, "RSVP-TE Signaling Extension for LSP Handover from
         the Management Plane to the Control Plane in a GMPLS-Enabled
         Transport Network", RFC 5852, April 2010.

   [21]  ITU-T Recommendation G.806, "Characteristics of transport
         equipment - Description methodology and generic functionality",
         January, 2009.

   [22]  ITU-T Recommendation Y.1731, "OAM functions and mechanisms for
         Ethernet based networks", February, 2008.

   [23]  ITU-T Recommendation G.8601, "Architecture of service
         management in multi bearer, multi carrier environment", June
         2006.

   [24]  Lam, H., Huynh, A., and D. Perkins, "Alarm Reporting Control
         Management Information Base (MIB)", RFC 3878, September 2004.

   [25]  ITU-T Recommendation Y.1563, "Ethernet frame transfer and
         availability performance", January 2009.

   [26]  Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet Denial-
         of-Service Considerations", RFC 4732, December 2006.






















Lam, et al.                  Standards Track                   [Page 21]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


Appendix A.  Communication Channel (CCh) Examples

   A CCh can be realized in a number of ways.

   1. The CCh can be provided by a link in a physically distinct
      network, that is, a link that is not part of the transport network
      that is being managed.  For example, the nodes in the transport
      network can be interconnected in two distinct physical networks:
      the transport network and the DCN.

   This is a "physically distinct out-of-band CCh".

   2. The CCh can be provided by a link in the transport network that is
      terminated at the ends of the DCC and that is capable of
      encapsulating and terminating packets of the management protocols.
      For example, in MPLS-TP, a single-hop LSP might be established
      between two adjacent nodes, and that LSP might be capable of
      carrying IP traffic.  Management traffic can then be inserted into
      the link in an LSP parallel to the LSPs that carry user traffic.

   This is a "physically shared out-of-band CCh."

   3. The CCh can be supported as its native protocol on the interface
      alongside the transported traffic.  For example, if an interface
      is capable of sending and receiving both MPLS-TP and IP, the IP-
      based management traffic can be sent as native IP packets on the
      interface.

   This is a "shared interface out-of-band CCh".

   4. The CCh can use overhead bytes available on a transport
      connection.  For example, in TDM networks there are overhead bytes
      associated with a data channel, and these can be used to provide a
      CCh.  It is important to note that the use of overhead bytes does
      not reduce the capacity of the associated data channel.

   This is an "overhead-based CCh".

   This alternative is not available in MPLS-TP because there is no
   overhead available.

   5. The CCh can be provided by a dedicated channel associated with the
      data link.  For example, the generic associated label (GAL) [14]
      can be used to label DCC traffic being exchanged on a data link
      between adjacent transport nodes, potentially in the absence of
      any data LSP between those nodes.





Lam, et al.                  Standards Track                   [Page 22]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   This is a "data link associated CCh".

   It is very similar to case 2, and by its nature can only span a
   single hop in the transport network.

   6. The CCh can be provided by a dedicated channel associated with a
      data channel.  For example, in MPLS-TP, the GAL [14] can be
      imposed under the top label in the label stack for an MPLS-TP LSP
      to create a channel associated with the LSP that can carry
      management traffic.  This CCh requires the receiver to be capable
      of demultiplexing management traffic from user traffic carried on
      the same LSP by use of the GAL.

   This is a "data channel associated CCh".

   7. The CCh can be provided by mixing the management traffic with the
      user traffic such that is indistinguishable on the link without
      deep-packet inspection.  In MPLS-TP, this could arise if there is
      a data-carrying LSP between two nodes, and management traffic is
      inserted into that LSP.  This approach requires that the
      termination point of the LSP be able to demultiplex the management
      and user traffic.  This might be possible in MPLS-TP if the MPLS-
      TP LSP is carrying IP user traffic.

   This is an "in-band CCh".

   These realizations can be categorized as:

      A. Out-of-fiber, out-of-band (types 1 and 2)
      B. In-fiber, out-of-band (types 2, 3, 4, and 5)
      C. In-band (types 6 and 7)

   The MCN and SCN are logically separate networks and can be realized
   by the same DCN or as separate networks.  In practice, that means
   that, between any pair of nodes, the MCC and SCC can be the same link
   or separate links.

   It is also important to note that the MCN and SCN do not need to be
   categorised as in-band, out-of-band, etc.  This definition only
   applies to the individual links, and it is possible for some nodes to
   be connected in the MCN or SCN by one type of link, and other nodes
   by other types of link.  Furthermore, a pair of adjacent nodes can be
   connected by multiple links of different types.

   Lastly, note that the division of DCN traffic between links between a
   pair of adjacent nodes is purely an implementation choice.  Parallel
   links can be deployed for DCN resilience or load sharing.  Links can
   be designated for specific use.  For example, so that some links



Lam, et al.                  Standards Track                   [Page 23]

RFC 5951        NM Requirements for MPLS-based Transport  September 2010


   carry management traffic and some carry control plane traffic, or so
   that some links carry signaling protocol traffic while others carry
   routing protocol traffic.

   It is important to note that the DCN can be a routed network with
   forwarding capabilities, but that this is not a requirement.  The
   ability to support forwarding of management or control traffic within
   the DCN can substantially simplify the topology of the DCN and
   improve its resilience, but does increase the complexity of operating
   the DCN.

   See also RFC 3877 [11], ITU-T M.20 [12], and Telcordia document
   GR-833-CORE [13] for further information.

Contributor's Address

   Adrian Farrel
   Old Dog Consulting
   EMail: adrian@olddog.co.uk

Authors' Addresses

   Eric Gray
   Ericsson
   900 Chelmsford Street
   Lowell, MA, 01851
   Phone: +1 978 275 7470
   EMail: Eric.Gray@Ericsson.com

   Scott Mansfield
   Ericsson
   250 Holger Way
   San Jose CA, 95134
   +1 724 931 9316
   EMail: Scott.Mansfield@Ericsson.com

   Hing-Kam (Kam) Lam
   Alcatel-Lucent
   600-700 Mountain Ave
   Murray Hill, NJ, 07974
   Phone: +1 908 582 0672
   EMail: Kam.Lam@Alcatel-Lucent.com









Lam, et al.                  Standards Track                   [Page 24]

