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rfc:rfc7759

Internet Engineering Task Force (IETF) E. Bellagamba Request for Comments: 7759 Category: Standards Track G. Mirsky ISSN: 2070-1721 Ericsson

                                                          L. Andersson
                                                   Huawei Technologies
                                                         P. Skoldstrom
                                                              Acreo AB
                                                               D. Ward
                                                                 Cisco
                                                              J. Drake
                                                               Juniper
                                                         February 2016
               Configuration of Proactive Operations,
   Administration, and Maintenance (OAM) Functions for MPLS-Based
      Transport Networks Using Label Switched Path (LSP) Ping

Abstract

 This specification describes the configuration of proactive MPLS-TP
 Operations, Administration, and Maintenance (OAM) functions for a
 given Label Switched Path (LSP) using a set of TLVs that are carried
 by the LSP Ping protocol.

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/rfc7759.

Bellagamba, et al. Standards Track [Page 1] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

Copyright Notice

 Copyright (c) 2016 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.

Table of Contents

 1. Introduction ....................................................3
    1.1. Conventions Used in This Document ..........................4
         1.1.1. Terminology .........................................4
         1.1.2. Requirements Language ...............................5
 2. Theory of Operations ............................................5
    2.1. MPLS OAM Configuration Operation Overview ..................5
         2.1.1. Configuration of BFD Sessions .......................5
         2.1.2. Configuration of Performance Monitoring .............6
         2.1.3. Configuration of Fault Management Signals ...........6
    2.2. MPLS OAM Functions TLV .....................................7
         2.2.1. BFD Configuration Sub-TLV ...........................9
         2.2.2. BFD Local Discriminator Sub-TLV ....................11
         2.2.3. BFD Negotiation Timer Parameters Sub-TLV ...........11
         2.2.4. BFD Authentication Sub-TLV .........................13
         2.2.5. Traffic Class Sub-TLV ..............................14
         2.2.6. Performance Monitoring Sub-TLV .....................14
         2.2.7. PM Loss Measurement Sub-TLV ........................17
         2.2.8. PM Delay Measurement Sub-TLV .......................18
         2.2.9. Fault Management Signal Sub-TLV ....................20
         2.2.10. Source MEP-ID Sub-TLV .............................21
 3. Summary of MPLS OAM Configuration Errors .......................22
 4. IANA Considerations ............................................23
    4.1. TLV and Sub-TLV Allocation ................................23
    4.2. MPLS OAM Function Flags Allocation ........................24
    4.3. OAM Configuration Errors ..................................25
 5. Security Considerations ........................................26
 6. References .....................................................26
    6.1. Normative References ......................................26
    6.2. Informative References ....................................27
 Acknowledgements  .................................................28
 Authors' Addresses ................................................29

Bellagamba, et al. Standards Track [Page 2] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

1. Introduction

 The MPLS Transport Profile (MPLS-TP) describes a profile of MPLS that
 enables operational models typical in transport networks while
 providing additional Operations, Administration, and Maintenance
 (OAM), survivability, and other maintenance functions not currently
 supported by MPLS.  [RFC5860] defines the requirements for the OAM
 functionality of MPLS-TP.
 This document describes the configuration of proactive MPLS-TP OAM
 functions for a given Label Switched Path (LSP) using TLVs carried in
 LSP Ping [RFC4379].  In particular, it specifies the mechanisms
 necessary to establish MPLS-TP OAM entities at the maintenance points
 for monitoring and performing measurements on an LSP, as well as
 defining information elements and procedures to configure proactive
 MPLS-TP OAM functions running between Label Edge Routers (LERs).
 Initialization and control of on-demand MPLS-TP OAM functions are
 expected to be carried out by directly accessing network nodes via a
 management interface; hence, configuration and control of on-demand
 OAM functions are out of scope for this document.
 The Transport Profile of MPLS must, by definition [RFC5654], be
 capable of operating without a control plane.  Therefore, there are a
 few options for configuring MPLS-TP OAM: without a control plane
 using a Network Management System (NMS), implementing LSP Ping
 instead or with a control plane implementing extensions to signaling
 protocols RSVP Traffic Engineering (RSVP-TE) [RFC3209] and/or
 Targeted LDP [RFC5036].
 Proactive MPLS-TP OAM is performed by a set of protocols:
 Bidirectional Forwarding Detection (BFD) [RFC6428] for Continuity
 Check/Connectivity Verification, the Delay Measurement (DM) protocol
 [RFC6374], [RFC6375] for delay and delay variation (jitter)
 measurements, and the Loss Measurement (LM) protocol [RFC6374],
 [RFC6375] for packet loss and throughput measurements.  Additionally,
 there are a number of Fault Management Signals that can be configured
 [RFC6427].
 BFD is a protocol that provides low-overhead, fast detection of
 failures in the path between two forwarding engines, including the
 interfaces, data link(s), and to the extent possible, the forwarding
 engines themselves.  BFD can be used to detect the continuity and
 mis-connection defects of MPLS-TP point-to-point and might also be
 extended to support point-to-multipoint LSPs.
 The delay and loss measurements protocols [RFC6374] and [RFC6375] use
 a simple query/response model for performing both unidirectional and
 bidirectional measurements that allow the originating node to measure

Bellagamba, et al. Standards Track [Page 3] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 packet loss and delay in forward, or forward and reverse directions.
 By timestamping and/or writing current packet counters to the
 measurement packets (four times, Transmit and Receive in both
 directions), current delays and packet losses can be calculated.  By
 performing successive delay measurements, the delay and/or inter-
 packet delay variation (jitter) can be calculated.  Current
 throughput can be calculated from the packet loss measurements by
 dividing the number of packets sent/received with the time it took to
 perform the measurement, given by the timestamp in the LM header.
 Combined with a packet generator, the throughput measurement can be
 used to measure the maximum capacity of a particular LSP.  It should
 be noted that this document does not specify how to configure
 on-demand throughput estimates based on saturating the connection as
 defined in [RFC6371]; rather, it only specifies how to enable the
 estimation of the current throughput based on loss measurements.

1.1. Conventions Used in This Document

1.1.1. Terminology

 BFD - Bidirectional Forwarding Detection
 DM - Delay Measurement
 FMS - Fault Management Signal
 G-ACh - Generic Associated Channel
 LSP - Label Switched Path
 LM - Loss Measurement
 MEP - Maintenance Entity Group End Point
 MPLS - Multi-Protocol Label Switching
 MPLS-TP - MPLS Transport Profile
 NMS - Network Management System
 PM - Performance Monitoring
 RSVP-TE - RSVP Traffic Engineering
 TC - Traffic Class

Bellagamba, et al. Standards Track [Page 4] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

1.1.2. Requirements Language

 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 [RFC2119].

2. Theory of Operations

2.1. MPLS OAM Configuration Operation Overview

 The MPLS-TP OAM tool set is described in [RFC6669].
 LSP Ping, or alternatively RSVP-TE [RFC7487], can be used to easily
 enable the different OAM functions by setting the corresponding flags
 in the MPLS OAM Functions TLV (refer to Section 2.2).  For a more
 detailed configuration, one may include sub-TLVs for the different
 OAM functions in order to specify various parameters in detail.
 Typically, intermediate nodes simply forward OAM configuration TLVs
 to the end node without any processing or modification.  At least one
 exception to this is if the FMS sub-TLV (refer to Section 2.2.9 ) is
 present.  This sub-TLV MUST be examined even by intermediate nodes
 that support this extension.  The sub-TLV MAY be present if a flag is
 set in the MPLS OAM Functions TLV.

2.1.1. Configuration of BFD Sessions

 For this specification, BFD MUST run in either one of the two modes:
 o  Asynchronous mode, where both sides are in active mode
 o  Unidirectional mode
 In the simplest scenario, LSP Ping [RFC5884], or alternatively RSVP-
 TE [RFC7487], is used only to bootstrap a BFD session for an LSP,
 without any timer negotiation.
 Timer negotiation can be performed either in subsequent BFD control
 messages (in this case the operation is similar to bootstrapping
 based on LSP Ping described in [RFC5884]), or directly in the LSP
 Ping configuration messages.
 When BFD Control packets are transported in the Associated Channel
 Header (ACH) encapsulation, they are not protected by any end-to-end
 checksum; only lower layers provide error detection/correction.  A
 single bit error, e.g., a flipped bit in the BFD State field, could
 cause the receiving end to wrongly conclude that the link is down and
 in turn trigger protection switching.  To prevent this from

Bellagamba, et al. Standards Track [Page 5] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 happening, the BFD Configuration sub-TLV (refer to Section 2.2.1) has
 an Integrity flag that, when set, enables BFD Authentication using
 Keyed SHA1 with an empty key (all 0s) [RFC5880].  This would make
 every BFD Control packet carry a SHA1 hash of itself that can be used
 to detect errors.
 If BFD Authentication using a pre-shared key/password is desired
 (i.e., authentication and not only error detection), the BFD
 Authentication sub-TLV (refer to Section 2.2.4) MUST be included in
 the BFD Configuration sub-TLV.  The BFD Authentication sub-TLV is
 used to specify which authentication method that should be used and
 which pre-shared key/password that should be used for this particular
 session.  How the key exchange is performed is out of scope of this
 document.

2.1.2. Configuration of Performance Monitoring

 It is possible to configure Performance Monitoring functionalities
 such as Loss, Delay, Delay/Interpacket Delay variation (jitter), and
 throughput as described in [RFC6374].
 When configuring Performance Monitoring functionalities, it is
 possible to choose either the default configuration, by only setting
 the respective flags in the MPLS OAM functions TLV, or a customized
 configuration.  To customize the configuration, one would set the
 respective flags in the MPLS OAM functions TLV and include the
 respective Loss and/or Delay sub-TLVs.
 By setting the PM Loss flag in the MPLS OAM Functions TLV and
 including the PM Loss sub-TLV (refer to Section 2.2.7), one can
 configure the measurement interval and loss threshold values for
 triggering protection.
 Delay measurements are configured by setting the PM Delay flag in the
 MPLS OAM Functions TLV and by including the PM Delay sub-TLV (refer
 to Section 2.2.8), one can configure the measurement interval and the
 delay threshold values for triggering protection.

2.1.3. Configuration of Fault Management Signals

 To configure Fault Management Signals (FMSs) and their refresh time,
 the FMS Flag in the MPLS OAM Functions TLV MUST be set and the FMS
 sub-TLV MUST be included.  When configuring an FMS, an implementation
 can enable the default configuration by setting the FMS Flag in the
 OAM Function Flags sub-TLV.  In order to modify the default
 configuration, the MPLS OAM FMS sub-TLV MUST be included.

Bellagamba, et al. Standards Track [Page 6] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 If an intermediate point is meant to originate FMS messages, this
 means that such an intermediate point is associated with a Server MEP
 through a co-located MPLS-TP client/server adaptation function, and
 the Fault Management subscription flag in the MPLS OAM FMS sub-TLV
 has been set as an indication of the request to create the
 association at each intermediate node of the client LSP.  The
 corresponding Server MEP needs to be configured by its own LSP Ping
 session or, alternatively, via a Network Management System (NMS) or
 RSVP-TE.

2.2. MPLS OAM Functions TLV

 The MPLS OAM Functions TLV presented in Figure 1 is carried as a TLV
 of the MPLS Echo Request/Reply messages [RFC4379].
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  MPLS OAM Func. Type (27)     |           Length              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                    MPLS OAM Function Flags                    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 ~                           sub-TLVs                            ~
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                Figure 1: MPLS OAM Functions TLV Format
 The MPLS OAM Functions TLV contains the MPLS OAM Function Flags
 field.  The MPLS OAM Function Flags indicate which OAM functions
 should be activated as well as OAM function-specific sub-TLVs with
 configuration parameters for the particular function.
 Type: Indicates the MPLS OAM Functions TLV (Section 4).
 Length: The length of the MPLS OAM Function Flags field including the
 total length of the sub-TLVs in octets.
 MPLS OAM Function Flags: A bitmap numbered from left to right as
 shown in Figure 2.  These flags are managed by IANA (refer to
 Section 4.2).  Flags defined in this document are presented in
 Table 2.  Undefined flags MUST be set to zero and unknown flags MUST
 be ignored.  The flags indicate what OAM is being configured and
 direct the presence of optional sub-TLVs as set out below.

Bellagamba, et al. Standards Track [Page 7] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |C|V|F|L|D|T|Unassigned MUST be zero (MBZ)                    |R|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               Figure 2: MPLS OAM Function Flags Format
 Sub-TLVs corresponding to the different flags are as follows.  No
 meaning should be attached to the order of sub-TLVs.
 o  If a flag in the MPLS OAM Function Flags is set and the
    corresponding sub-TLVs listed below are absent, then this MPLS OAM
    function MUST be initialized according to its default settings.
    Default settings of MPLS OAM functions are outside the scope of
    this document.
 o  If any sub-TLV is present without the corresponding flag being
    set, the sub-TLV SHOULD be ignored.
 o  BFD Configuration sub-TLV, which MUST be included if either the
    CC, the CV, or both MPLS OAM Function flags are being set in the
    MPLS OAM Functions TLV.
 o  Performance Monitoring sub-TLV MUST be used to carry PM Loss sub-
    TLV and/or PM Delay sub-TLV.  If neither one of these sub-TLVs is
    present, then Performance Monitoring sub-TLV SHOULD NOT be
    included.  Empty, i.e., no enclosed sub-TLVs, Performance
    Monitoring sub-TLV SHOULD be ignored.
 o  PM Loss sub-TLV MAY be included if the PM/Loss OAM Function flag
    is set.  If the "PM Loss sub-TLV" is not included, default
    configuration values are used.  Such sub-TLV MAY also be included
    in case the Throughput function flag is set and there is the need
    to specify a measurement interval different from the default ones.
    In fact, the throughput measurement makes use of the same tool as
    the loss measurement; hence, the same TLV is used.
 o  PM Delay sub-TLV MAY be included if the PM/Delay OAM Function flag
    is set.  If the "PM Delay sub-TLV" is not included, default
    configuration values are used.
 o  FMS sub-TLV, that MAY be included if the FMS OAM Function flag is
    set.  If the "FMS sub-TLV" is not included, default configuration
    values are used.

Bellagamba, et al. Standards Track [Page 8] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 If all flags in the MPLS OAM Function Flags field have the same value
 of zero, that MUST be interpreted as meaning that the MPLS OAM
 Functions TLV is not present in the MPLS Echo Request.  If more than
 one MPLS OAM Functions TLV is present in the MPLS Echo request
 packet, then the first TLV SHOULD be processed and the rest ignored.
 Any parsing error within nested sub-TLVs that is not specified in
 Section 3 SHOULD be treated as described in [RFC4379].

2.2.1. BFD Configuration Sub-TLV

 The BFD Configuration sub-TLV, depicted in Figure 3, is defined for
 BFD OAM-specific configuration parameters.  The "BFD Configuration
 sub-TLV" is carried as a sub-TLV of the "OAM Functions TLV".
 This TLV accommodates generic BFD OAM information and carries sub-
 TLVs.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | BFD Conf. Sub-type    (100)   |           Length              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |Vers.|N|S|I|G|U|B|         Reserved (set to all 0s)            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 ~                           sub-TLVs                            ~
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Figure 3: BFD Configuration Sub-TLV Format
 Sub-type: Indicates a new sub-type, the BFD Configuration sub-TLV
 (value 100).
 Length: Indicates the length of the Value field in octets.
 Version: Identifies the BFD protocol version.  If a node does not
 support a specific BFD version, an error must be generated: "OAM
 Problem/Unsupported BFD Version".
 BFD Negotiation (N): If set, timer negotiation/renegotiation via BFD
 Control Messages is enabled.  When cleared, it is disabled and timer
 configuration is achieved using the BFD Negotiation Timer Parameters
 sub-TLV as described in Section 2.2.3.
 Symmetric session (S): If set, the BFD session MUST use symmetric
 timing values.  If cleared, the BFD session MAY use any timing values
 either negotiated or explicitly configured.

Bellagamba, et al. Standards Track [Page 9] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 Integrity (I): If set, BFD Authentication MUST be enabled.  If the
 BFD Configuration sub-TLV does not include a BFD Authentication sub-
 TLV, the authentication MUST use Keyed SHA1 with an empty pre-shared
 key (all 0s).  If the egress LSR does not support BFD Authentication,
 an error MUST be generated: "OAM Problem/BFD Authentication
 unsupported".  If the Integrity flag is clear, then Authentication
 MUST NOT be used.
 Encapsulation Capability (G): If set, it shows the capability of
 encapsulating BFD messages into the G-ACh channel.  If both the G bit
 and U bit are set, configuration gives precedence to the G bit.
 Encapsulation Capability (U): If set, it shows the capability of
 encapsulating BFD messages into IP/UDP packets.  If both the G bit
 and U bit are set, configuration gives precedence to the G bit.
 If the egress LSR does not support any of the ingress LSR
 Encapsulation Capabilities, an error MUST be generated: "OAM Problem/
 Unsupported BFD Encapsulation format".
 Bidirectional (B): If set, it configures BFD in the Bidirectional
 mode.  If it is not set, it configures BFD in the unidirectional
 mode.  In the second case, the source node does not expect any
 Discriminator values back from the destination node.
 Reserved: Reserved for future specification; set to 0 on transmission
 and ignored when received.
 The BFD Configuration sub-TLV MUST include the following sub-TLVs in
 the MPLS Echo Request message:
 o  BFD Local Discriminator sub-TLV, if the B flag is set in the MPLS
    Echo Request;
 o  BFD Negotiation Timer Parameters sub-TLV, if the N flag is
    cleared.
 The BFD Configuration sub-TLV MUST include the following sub-TLVs in
 the MPLS Echo Reply message:
 o  BFD Local Discriminator sub-TLV;
 o  BFD Negotiation Timer Parameters sub-TLV if:
  • The N and S flags are cleared, or if:
  • The N flag is cleared and the S flag is set, and the BFD

Negotiation Timer Parameters sub-TLV received by the egress

Bellagamba, et al. Standards Track [Page 10] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

       contains unsupported values.  In this case, an updated BFD
       Negotiation Timer Parameters sub-TLV, containing values
       supported by the egress node [RFC7419], is returned to the
       ingress.

2.2.2. BFD Local Discriminator Sub-TLV

 The BFD Local Discriminator sub-TLV is carried as a sub-TLV of the
 "BFD Configuration sub-TLV" and is depicted in Figure 4.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  Locl. Discr. Sub-type (101)  |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       Local Discriminator                     |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Figure 4: BFD Local Discriminator Sub-TLV Format
 Sub-type: Indicates a new sub-type, the "BFD Local Discriminator sub-
 TLV" (value 101).
 Length: Indicates the length of the Value field in octets (4).
 Local Discriminator: A nonzero discriminator value that is unique in
 the context of the transmitting system that generates it.  It is used
 to demultiplex multiple BFD sessions between the same pair of
 systems.

2.2.3. BFD Negotiation Timer Parameters Sub-TLV

 The BFD Negotiation Timer Parameters sub-TLV is carried as a sub-TLV
 of the BFD Configuration sub-TLV and is depicted in Figure 5.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Nego. Timer Sub-type (102)    |             Length            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |         Acceptable Min. Asynchronous TX interval              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |         Acceptable Min. Asynchronous RX interval              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |               Required Echo TX Interval                       |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       Figure 5: BFD Negotiation Timer Parameters Sub-TLV Format

Bellagamba, et al. Standards Track [Page 11] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 Sub-type: Indicates a new sub-type, the BFD Negotiation Timer
 Parameters sub-TLV (value 102).
 Length: Indicates the length of the Value field in octets (12).
 Acceptable Min. Asynchronous TX interval: If the S (symmetric) flag
 is set in the BFD Configuration sub-TLV, defined in Section 2.2.1, it
 expresses the desired time interval (in microseconds) at which the
 ingress LER intends to both transmit and receive BFD periodic control
 packets.  If the receiving edge LSR cannot support such a value, it
 SHOULD reply with an interval greater than the one proposed.
 If the S (symmetric) flag is cleared in the BFD Configuration sub-
 TLV, this field expresses the desired time interval (in microseconds)
 at which an edge LSR intends to transmit BFD periodic control packets
 in its transmitting direction.
 Acceptable Min. Asynchronous RX interval: If the S (symmetric) flag
 is set in the BFD Configuration sub-TLV, Figure 3, this field MUST be
 equal to Acceptable Min. Asynchronous TX interval and has no
 additional meaning respect to the one described for "Acceptable Min.
 Asynchronous TX interval".
 If the S (symmetric) flag is cleared in the BFD Configuration sub-
 TLV, it expresses the minimum time interval (in microseconds) at
 which edge LSRs can receive BFD periodic control packets.  If this
 value is greater than the value of Acceptable Min. Asynchronous TX
 interval received from the other edge LSR, such an edge LSR MUST
 adopt the interval expressed in this Acceptable Min. Asynchronous RX
 interval.
 Required Echo TX Interval: The minimum interval (in microseconds)
 between received BFD Echo packets that this system is capable of
 supporting, less any jitter applied by the sender as described in
 Section 6.8.9 of [RFC5880].  This value is also an indication for the
 receiving system of the minimum interval between transmitted BFD Echo
 packets.  If this value is zero, the transmitting system does not
 support the receipt of BFD Echo packets.  If the receiving system
 cannot support this value, the "Unsupported BFD TX Echo rate
 interval" error MUST be generated.  By default, the value is set to
 0.

Bellagamba, et al. Standards Track [Page 12] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

2.2.4. BFD Authentication Sub-TLV

 The "BFD Authentication sub-TLV" is carried as a sub-TLV of the "BFD
 Configuration sub-TLV" and is depicted in Figure 6.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |    BFD Auth. Sub-type (103)   |             Length            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |   Auth Type   |  Auth Key ID  |         Reserved (0s)         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Figure 6: BFD Authentication Sub-TLV Format
 Sub-type: Indicates a new sub-type, the BFD Authentication sub-TLV
 (value 103).
 Length: Indicates the length of the Value field in octets (4).
 Auth Type: Indicates which type of authentication to use.  The same
 values as are defined in Section 4.1 of [RFC5880] are used.  Simple
 Password SHOULD NOT be used if other authentication types are
 available.
 Auth Key ID: Indicates which authentication key or password
 (depending on Auth Type) should be used.  How the key exchange is
 performed is out of scope of this document.  If the egress LSR does
 not support this Auth Key ID, an "OAM Problem/Mismatch of BFD
 Authentication Key ID" error MUST be generated.
 Reserved: Reserved for future specification; set to 0 on transmission
 and ignored when received.
 An implementation MAY change the mode of authentication if an
 operator re-evaluates the security situation in and around the
 administrative domain.  If the BFD Authentication sub-TLV is used for
 a BFD session in Up state, then the Sender of the MPLS LSP Echo
 Request SHOULD ensure that old and new modes of authentication, i.e.,
 a combination of Auth.Type and Auth.  Key ID, are used to send and
 receive BFD control packets, until the Sender can confirm that its
 peer has switched to the new authentication.

Bellagamba, et al. Standards Track [Page 13] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

2.2.5. Traffic Class Sub-TLV

 The Traffic Class sub-TLV is carried as a sub-TLV of the "BFD
 Configuration sub-TLV" and "Fault Management Signal Sub-TLV"
 (Section 2.2.9) and is depicted in Figure 7.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Traffic Class Sub-type (104)  |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  TC |                 Reserved (set to all 0s)                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                Figure 7: Traffic Class Sub-TLV Format
 Sub-type: Indicates a new sub-type, the "Traffic Class sub-TLV"
 (value 104).
 Length: Indicates the length of the Value field in octets (4).
 TC: Identifies the Traffic Class (TC) [RFC5462] for periodic
 continuity monitoring messages or packets with fault management
 information.
 If the TC sub-TLV is present, then the sender of any periodic
 continuity monitoring messages or packets with fault management
 information on the LSP, with a Forwarding Equivalence Class (FEC)
 that corresponds to the FEC for which fault detection is being
 performed, MUST use the value contained in the TC field of the sub-
 TLV as the value of the TC field in the top label stack entry of the
 MPLS label stack.  If the TC sub-TLV is absent from either "BFD
 Configuration sub-TLV" or "Fault Management Signal sub-TLV", then
 selection of the TC value is a local decision.

2.2.6. Performance Monitoring Sub-TLV

 If the MPLS OAM Functions TLV has any of the L (Loss), D (Delay), and
 T (Throughput) flags set, the Performance Monitoring sub-TLV MUST be
 present.  Failure to include the correct sub-TLVs MUST result in an
 "OAM Problem/PM Configuration Error" being generated.
 The Performance Monitoring sub-TLV provides the configuration
 information mentioned in Section 7 of [RFC6374].  It includes support
 for the configuration of quality thresholds and, as described in
 [RFC6374]:

Bellagamba, et al. Standards Track [Page 14] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

    ...the crossing of which will trigger warnings or alarms, and
    result in reporting and exception notification will be integrated
    into the system-wide network management and reporting framework.
 In case the values need to be different than the default ones, the
 Performance Monitoring sub-TLV MAY include the following sub-TLVs:
 o  PM Loss sub-TLV, if the L flag is set in the MPLS OAM Functions
    TLV;
 o  PM Delay sub-TLV, if the D flag is set in the MPLS OAM Functions
    TLV.
 The Performance Monitoring sub-TLV depicted in Figure 8 is carried as
 a sub-TLV of the MPLS OAM Functions TLV.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |Perf. Monitoring Sub-type (200)|          Length               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                     PM Configuration Flags                    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 ~                           sub-TLVs                            ~
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Figure 8: Performance Monitoring Sub-TLV Format
 Sub-type: Indicates a new sub-type, the Performance Monitoring sub-
 TLV (value 200).
 Length: Indicates the length of the Value field in octets, including
 PM Configuration Flags and optional sub-TLVs.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |D|L|J|Y|K|C|            Reserved (set to all 0s)               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                Figure 9: PM Configuration Flags Format

Bellagamba, et al. Standards Track [Page 15] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 The PM Configuration Flags format is presented in Figure 9.  For the
 specific function description, please refer to [RFC6374]:
 D:    Delay inferred/direct (0=INFERRED, 1=DIRECT).  If the egress
       LSR does not support the specified mode, an "OAM Problem/
       Unsupported Delay Mode" error MUST be generated.
 L:    Loss inferred/direct (0=INFERRED, 1=DIRECT).  If the egress LSR
       does not support the specified mode, an "OAM Problem/
       Unsupported Loss Mode" error MUST be generated.
 J:    Delay variation/jitter (1=ACTIVE, 0=NOT ACTIVE).  If the egress
       LSR does not support Delay variation measurements and the J
       flag is set, an "OAM Problem/Delay variation unsupported" error
       MUST be generated.
 Y:    Dyadic (1=ACTIVE, 0=NOT ACTIVE).  If the egress LSR does not
       support Dyadic mode and the Y flag is set, an "OAM Problem/
       Dyadic mode unsupported" error MUST be generated.
 K:    Loopback (1=ACTIVE, 0=NOT ACTIVE).  If the egress LSR does not
       support Loopback mode and the K flag is set, an "OAM Problem/
       Loopback mode unsupported" error MUST be generated.
 C:    Combined (1=ACTIVE, 0=NOT ACTIVE).  If the egress LSR does not
       support Combined mode and the C flag is set, an "OAM Problem/
       Combined mode unsupported" error MUST be generated.
 Reserved:  Reserved for future specification; set to 0 on
       transmission and ignored when received.

Bellagamba, et al. Standards Track [Page 16] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

2.2.7. PM Loss Measurement Sub-TLV

 The PM Loss Measurement sub-TLV depicted in Figure 10 is carried as a
 sub-TLV of the Performance Monitoring sub-TLV.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  PM Loss Sub-type (201)       |          Length               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | OTF |T|B|              Reserved (set to all 0s)               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                    Measurement Interval                       |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       Test Interval                           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      Loss Threshold                           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             Figure 10: PM Loss Measurement Sub-TLV Format
 Sub-type: Indicates a new sub-type, the PM Loss Measurement sub-TLV
 (value 201).
 Length: Indicates the length of the Value field in octets (16).
 OTF: Origin Timestamp Format of the Origin Timestamp field described
 in [RFC6374].  By default, it is set to IEEE 1588 version 1.  If the
 egress LSR cannot support this value, an "OAM Problem/Unsupported
 Timestamp Format" error MUST be generated.
 Configuration Flags, please refer to [RFC6374] for further details:
 T:    Traffic-class-specific measurement indicator.  Set to 1 when
       the measurement operation is scoped to packets of a particular
       traffic class (Differentiated Services Code Point value), and 0
       otherwise.  When set to 1, the Differentiated Services (DS)
       field of the message indicates the measured traffic class.  By
       default, it is set to 1.
 B:    Octet (byte) count.  When set to 1, indicates that the Counter
       1-4 fields represent octet counts.  When set to 0, indicates
       that the Counter 1-4 fields represent packet counts.  By
       default, it is set to 0.
 Reserved: Reserved for future specification; set to 0 on transmission
 and ignored when received.

Bellagamba, et al. Standards Track [Page 17] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 Measurement Interval: The time interval (in milliseconds) at which
 Loss Measurement query messages MUST be sent on both directions.  If
 the edge LSR receiving the Path message cannot support such a value,
 it SHOULD reply with a higher interval.  By default, it is set to
 (100) as per [RFC6375].
 Test Interval: Test messages interval in milliseconds as described in
 [RFC6374].  By default, it is set to (10) as per [RFC6375].
 Loss Threshold: The threshold value of measured lost packets per
 measurement over which action(s) SHOULD be triggered.

2.2.8. PM Delay Measurement Sub-TLV

 The "PM Delay Measurement sub-TLV" depicted in Figure 11 is carried
 as a sub-TLV of the Performance Monitoring sub-TLV.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  PM Delay Sub-type (202)      |          Length               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | OTF |T|B|             Reserved (set to all 0s)                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                    Measurement Interval                       |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       Test Interval                           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      Delay Threshold                          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Figure 11: PM Delay Measurement Sub-TLV Format
 Sub-type: Indicates a new sub-type, the "PM Delay Measurement sub-
 TLV" (value 202).
 Length: Indicates the length of the Value field in octets (16).
 OTF: Origin Timestamp Format of the Origin Timestamp field described
 in [RFC6374].  By default, it is set to IEEE 1588 version 1.  If the
 egress LSR cannot support this value, an "OAM Problem/Unsupported
 Timestamp Format" error MUST be generated.

Bellagamba, et al. Standards Track [Page 18] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 Configuration Flags, please refer to [RFC6374] for further details:
 T:    Traffic-class-specific measurement indicator.  Set to 1 when
       the measurement operation is scoped to packets of a particular
       traffic class (Differentiated Services Code Point value), and 0
       otherwise.  When set to 1, the DS field of the message
       indicates the measured traffic class.  By default, it is set to
       1.
 B:    Octet (byte) count.  When set to 1, indicates that the Counter
       1-4 fields represent octet counts.  When set to 0, indicates
       that the Counter 1-4 fields represent packet counts.  By
       default, it is set to 0.
 Reserved: Reserved for future specification; set to 0 on transmission
 and ignored when received.
 Measurement Interval: The time interval (in milliseconds) at which
 Delay Measurement query messages MUST be sent on both directions.  If
 the edge LSR receiving the Path message cannot support such a value,
 it can reply with a higher interval.  By default, it is set to (1000)
 as per [RFC6375].
 Test Interval: Test messages interval (in milliseconds) as described
 in [RFC6374].  By default, it is set to (10) as per [RFC6375].
 Delay Threshold: The threshold value of measured two-way delay (in
 milliseconds) over which action(s) SHOULD be triggered.

Bellagamba, et al. Standards Track [Page 19] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

2.2.9. Fault Management Signal Sub-TLV

 The FMS sub-TLV depicted in Figure 12 is carried as a sub-TLV of the
 MPLS OAM Configuration sub-TLV.  When both working and protection
 paths are configured, both LSPs SHOULD be configured with identical
 settings of the E flag, T flag, and the refresh timer.  An
 implementation MAY configure the working and protection LSPs with
 different settings of these fields in case of 1:N protection.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |       FMS Sub-type (300)      |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |E|S|T|            Reserved           |      Refresh Timer      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 ~                           sub-TLVs                            ~
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Figure 12: Fault Management Signal Sub-TLV Format
 Sub-type: Indicates a new sub-type, the FMS sub-TLV (value 300).
 Length: Indicates the length of the Value field in octets.
 FMS Flags are used to enable the FMS Flags at end point MEPs and the
 Server MEPs of the links over which the LSP is forwarded.  In this
 document, only the S flag pertains to Server MEPs.
 The following flags are defined:
 E:    Enable Alarm Indication Signal (AIS) and Lock Report (LKR)
       signaling as described in [RFC6427].  Default value is 1
       (enabled).  If the egress MEP does not support FMS Flag
       generation, an "OAM Problem/Fault management signaling
       unsupported" error MUST be generated.
 S:    Indicate to a Server MEP that it should transmit AIS and LKR
       signals on the client LSP.  Default value is 0 (disabled).  If
       a Server MEP that is capable of generating FMS messages is, for
       some reason, unable to do so for the LSP being signaled, an
       "OAM Problem/Unable to create fault management association"
       error MUST be generated.
 T:    Set timer value, enabled the configuration of a specific timer
       value.  Default value is 0 (disabled).

Bellagamba, et al. Standards Track [Page 20] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 Reserved: Bits 4-16 that follow the FMS Flags are reserved for future
 allocation.  These bits MUST be set to 0 on transmit and ignored on
 receipt if not allocated.
 Refresh Timer: Indicates the refresh timer of fault indication
 messages, in seconds.  The value MUST be between 1 to 20 seconds as
 specified for the Refresh Timer field in [RFC6427].  If the edge LSR
 receiving the Path message cannot support the value, it SHOULD reply
 with a higher timer value.
 FMS sub-TLV MAY include Traffic Class sub-TLV (Section 2.2.5).  If
 the TC sub-TLV is present, the value of the TC field MUST be used as
 the value of the TC field of an MPLS label stack entry for FMS
 messages.  If the TC sub-TLV is absent, then selection of the TC
 value is a local decision.

2.2.10. Source MEP-ID Sub-TLV

 The Source MEP-ID sub-TLV depicted in Figure 13 is carried as a sub-
 TLV of the MPLS OAM Functions TLV.
 Note that support of ITU IDs is out of scope.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Source MEP-ID Sub-type (400)  |           Length              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       Source Node ID                          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |           Tunnel ID           |           LSP ID              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                Figure 13: Source MEP-ID Sub-TLV Format
 Sub-type: Indicates a new sub-type, the Source MEP-ID sub-TLV (value
 400).
 Length: Indicates the length of the Value field in octets (8).
 Source Node ID: 32-bit node identifier as defined in [RFC6370].
 Tunnel ID: A 16-bit unsigned integer unique to the node as defined in
 [RFC6370].
 LSP ID: A 16-bit unsigned integer unique within the Tunnel_ID as
 defined in [RFC6370].

Bellagamba, et al. Standards Track [Page 21] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

3. Summary of MPLS OAM Configuration Errors

 This is the summary of Return Codes [RFC4379] defined in this
 document:
 o  If an egress LSR does not support the specified BFD version, an
    error MUST be generated: "OAM Problem/Unsupported BFD Version".
 o  If an egress LSR does not support the specified BFD Encapsulation
    format, an error MUST be generated: "OAM Problem/Unsupported BFD
    Encapsulation format".
 o  If an egress LSR does not support BFD Authentication, and it is
    requested, an error MUST be generated: "OAM Problem/BFD
    Authentication unsupported".
 o  If an egress LSR does not support the specified BFD Authentication
    Type, an error MUST be generated: "OAM Problem/Unsupported BFD
    Authentication Type".
 o  If an egress LSR is not able to use the specified Authentication
    Key ID, an error MUST be generated: "OAM Problem/Mismatch of BFD
    Authentication Key ID".
 o  If PM flags in MPLS OAM Functions TLV don't have corresponding PM
    sub-TLVs present, an error MUST be generated: "OAM Problem/PM
    Configuration Error".
 o  If an egress LSR does not support the specified Timestamp Format,
    an error MUST be generated: "OAM Problem/Unsupported Timestamp
    Format".
 o  If an egress LSR does not support specified Delay mode, an "OAM
    Problem/Unsupported Delay Mode" error MUST be generated.
 o  If an egress LSR does not support specified Loss mode, an "OAM
    Problem/Unsupported Loss Mode" error MUST be generated.
 o  If an egress LSR does not support Delay variation measurements,
    and it is requested, an "OAM Problem/Delay variation unsupported"
    error MUST be generated.
 o  If an egress LSR does not support Dyadic mode, and it is
    requested, an "OAM Problem/Dyadic mode unsupported" error MUST be
    generated.

Bellagamba, et al. Standards Track [Page 22] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 o  If an egress LSR does not support Loopback mode, and it is
    requested, an "OAM Problem/Loopback mode unsupported" error MUST
    be generated.
 o  If an egress LSR does not support Combined mode, and it is
    requested, an "OAM Problem/Combined mode unsupported" error MUST
    be generated.
 o  If an egress LSR does not support Fault Monitoring Signals, and it
    is requested, an "OAM Problem/Fault management signaling
    unsupported" error MUST be generated.
 o  If an intermediate Server MEP supports Fault Monitoring Signals,
    but is unable to create an association, when requested to do so,
    an "OAM Problem/Unable to create fault management association"
    error MUST be generated.
 Ingress LSR MAY combine multiple MPLS OAM configuration TLVs and sub-
 TLVs into single MPLS echo request.  In case an egress LSR doesn't
 support any of the requested modes, it MUST set the return code to
 report the first unsupported mode in the list of TLVs and sub-TLVs.
 And if any of the requested OAM configuration is not supported, the
 egress LSR SHOULD NOT process OAM Configuration TLVs and sub-TLVs
 listed in the MPLS echo request.

4. IANA Considerations

4.1. TLV and Sub-TLV Allocation

 IANA maintains the "Multi-Protocol Label Switching (MPLS) Label
 Switched Paths (LSPs) Ping Parameters" registry and, within that
 registry, a subregistry for TLVs and sub-TLVs.
 IANA has allocated a new MPLS OAM Functions TLV from the Standards
 Action [RFC5226] range (0-16383) and sub-TLVs as follows from
 subregistry presented in Table 1, called "Sub-TLVs for TLV Type 27".
 Registration procedures for Sub-TLVs from ranges 0-16383 and
 32768-49161 are by Standards Action.  Ranges 16384-31743 and
 49162-64511 are through Specification Required (Experimental RFC
 Needed).

Bellagamba, et al. Standards Track [Page 23] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 +------+----------+---------------------------------+---------------+
 | Type | Sub-type | Value Field                     | Reference     |
 +------+----------+---------------------------------+---------------+
 | 27   |          | MPLS OAM Functions              | This document |
 |      | 100      | BFD Configuration               | This document |
 |      | 101      | BFD Local Discriminator         | This document |
 |      | 102      | BFD Negotiation Timer           | This document |
 |      |          | Parameters                      |               |
 |      | 103      | BFD Authentication              | This document |
 |      | 104      | Traffic Class                   | This document |
 |      | 200      | Performance Monitoring          | This document |
 |      | 201      | PM Loss Measurement             | This document |
 |      | 202      | PM Delay Measurement            | This document |
 |      | 300      | Fault Management Signal         | This document |
 |      | 400      | Source MEP-ID                   | This document |
 +------+----------+---------------------------------+---------------+
                   Table 1: IANA TLV Type Allocation

4.2. MPLS OAM Function Flags Allocation

 IANA has created a new registry called the "MPLS OAM Function Flags"
 registry.  Assignments of bit positions 0 through 31 are via
 Standards Action.  The new registry is to be populated as follows.
 +------------+--------------------+---------------------------------+
 |    Bit     | MPLS OAM Function  | Description                     |
 |  Position  |        Flag        |                                 |
 +------------+--------------------+---------------------------------+
 |     0      |         C          | Continuity Check (CC)           |
 |     1      |         V          | Connectivity Verification (CV)  |
 |     2      |         F          | Fault Management Signal (FMS)   |
 |     3      |         L          | Performance Monitoring/Loss     |
 |            |                    | (PM/Loss)                       |
 |     4      |         D          | Performance Monitoring/Delay    |
 |            |                    | (PM/Delay)                      |
 |     5      |         T          | Throughput Measurement          |
 |    6-30    |                    | Unassigned (Must be zero)       |
 |     31     |                    | Reserved                        |
 +------------+--------------------+---------------------------------+
                   Table 2: MPLS OAM Function Flags

Bellagamba, et al. Standards Track [Page 24] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

4.3. OAM Configuration Errors

 IANA maintains a registry "Multi-Protocol Label Switching (MPLS)
 Label Switched Paths (LSPs) Ping Parameters", and within that
 registry a subregistry "Return Codes".
 IANA has assigned new Return Codes from the Standards Action range
 (0-191) as follows:
 +----------------+--------------------------------------+-----------+
 | Error Value    | Description                          | Reference |
 | Sub-codes      |                                      |           |
 +----------------+--------------------------------------+-----------+
 | 21             | OAM Problem/Unsupported BFD Version  | This      |
 |                |                                      | document  |
 | 22             | OAM Problem/Unsupported BFD          | This      |
 |                | Encapsulation format                 | document  |
 | 23             | OAM Problem/Unsupported BFD          | This      |
 |                | Authentication Type                  | document  |
 | 24             | OAM Problem/Mismatch of BFD          | This      |
 |                | Authentication Key ID                | document  |
 | 25             | OAM Problem/Unsupported Timestamp    | This      |
 |                | Format                               | document  |
 | 26             | OAM Problem/Unsupported Delay Mode   | This      |
 |                |                                      | document  |
 | 27             | OAM Problem/Unsupported Loss Mode    | This      |
 |                |                                      | document  |
 | 28             | OAM Problem/Delay variation          | This      |
 |                | unsupported                          | document  |
 | 29             | OAM Problem/Dyadic mode unsupported  | This      |
 |                |                                      | document  |
 | 30             | OAM Problem/Loopback mode            | This      |
 |                | unsupported                          | document  |
 | 31             | OAM Problem/Combined mode            | This      |
 |                | unsupported                          | document  |
 | 32             | OAM Problem/Fault management         | This      |
 |                | signaling unsupported                | document  |
 | 33             | OAM Problem/Unable to create fault   | This      |
 |                | management association               | document  |
 | 34             | OAM Problem/PM Configuration Error   | This      |
 |                |                                      | document  |
 +----------------+--------------------------------------+-----------+
                 Table 3: IANA Return Codes Allocation

Bellagamba, et al. Standards Track [Page 25] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

5. Security Considerations

 The signaling of OAM-related parameters and the automatic
 establishment of OAM entities introduces additional security
 considerations to those discussed in [RFC4379].  In particular, a
 network element could be overloaded if an attacker were to request
 high-frequency liveliness monitoring of a large number of LSPs,
 targeting a single network element.  Implementations must be made
 cognizant of available OAM resources and MAY refuse new OAM
 configurations that would overload a node.  Additionally, policies to
 manage OAM resources may be used to provide some fairness in OAM
 resource distribution among monitored LSPs.
 Security of OAM protocols configured with extensions to LSP Ping
 described in this document are discussed in [RFC5880], [RFC5884],
 [RFC6374], [RFC6427], and [RFC6428].
 In order that the configuration of OAM functionality can be achieved
 securely through the techniques described in this document, security
 mechanisms must already be in place and operational for LSP Ping.
 Thus, the exchange of security parameters (such as keys) for use in
 securing OAM is outside the scope of this document and is assumed to
 use an off-line mechanism or an established secure key exchange
 protocol.
 Additional discussion of security for MPLS protocols can be found in
 [RFC5920].

6. References

6.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC4379]  Kompella, K. and G. Swallow, "Detecting Multi-Protocol
            Label Switched (MPLS) Data Plane Failures", RFC 4379,
            DOI 10.17487/RFC4379, February 2006,
            <http://www.rfc-editor.org/info/rfc4379>.
 [RFC5654]  Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
            Sprecher, N., and S. Ueno, "Requirements of an MPLS
            Transport Profile", RFC 5654, DOI 10.17487/RFC5654,
            September 2009, <http://www.rfc-editor.org/info/rfc5654>.

Bellagamba, et al. Standards Track [Page 26] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
            (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
            <http://www.rfc-editor.org/info/rfc5880>.
 [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
            "Bidirectional Forwarding Detection (BFD) for MPLS Label
            Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
            June 2010, <http://www.rfc-editor.org/info/rfc5884>.
 [RFC6370]  Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
            Profile (MPLS-TP) Identifiers", RFC 6370,
            DOI 10.17487/RFC6370, September 2011,
            <http://www.rfc-editor.org/info/rfc6370>.
 [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
            Measurement for MPLS Networks", RFC 6374,
            DOI 10.17487/RFC6374, September 2011,
            <http://www.rfc-editor.org/info/rfc6374>.
 [RFC6427]  Swallow, G., Ed., Fulignoli, A., Ed., Vigoureux, M., Ed.,
            Boutros, S., and D. Ward, "MPLS Fault Management
            Operations, Administration, and Maintenance (OAM)",
            RFC 6427, DOI 10.17487/RFC6427, November 2011,
            <http://www.rfc-editor.org/info/rfc6427>.
 [RFC6428]  Allan, D., Ed., Swallow Ed., G., and J. Drake Ed.,
            "Proactive Connectivity Verification, Continuity Check,
            and Remote Defect Indication for the MPLS Transport
            Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
            <http://www.rfc-editor.org/info/rfc6428>.

6.2. Informative References

 [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
            and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
            Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
            <http://www.rfc-editor.org/info/rfc3209>.
 [RFC5036]  Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
            "LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
            October 2007, <http://www.rfc-editor.org/info/rfc5036>.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            DOI 10.17487/RFC5226, May 2008,
            <http://www.rfc-editor.org/info/rfc5226>.

Bellagamba, et al. Standards Track [Page 27] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

 [RFC5462]  Andersson, L. and R. Asati, "Multiprotocol Label Switching
            (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
            Class" Field", RFC 5462, DOI 10.17487/RFC5462, February
            2009, <http://www.rfc-editor.org/info/rfc5462>.
 [RFC5860]  Vigoureux, M., Ed., Ward, D., Ed., and M. Betts, Ed.,
            "Requirements for Operations, Administration, and
            Maintenance (OAM) in MPLS Transport Networks", RFC 5860,
            DOI 10.17487/RFC5860, May 2010,
            <http://www.rfc-editor.org/info/rfc5860>.
 [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
            Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
            <http://www.rfc-editor.org/info/rfc5920>.
 [RFC6371]  Busi, I., Ed. and D. Allan, Ed., "Operations,
            Administration, and Maintenance Framework for MPLS-Based
            Transport Networks", RFC 6371, DOI 10.17487/RFC6371,
            September 2011, <http://www.rfc-editor.org/info/rfc6371>.
 [RFC6375]  Frost, D., Ed. and S. Bryant, Ed., "A Packet Loss and
            Delay Measurement Profile for MPLS-Based Transport
            Networks", RFC 6375, DOI 10.17487/RFC6375, September 2011,
            <http://www.rfc-editor.org/info/rfc6375>.
 [RFC6669]  Sprecher, N. and L. Fang, "An Overview of the Operations,
            Administration, and Maintenance (OAM) Toolset for MPLS-
            Based Transport Networks", RFC 6669, DOI 10.17487/RFC6669,
            July 2012, <http://www.rfc-editor.org/info/rfc6669>.
 [RFC7419]  Akiya, N., Binderberger, M., and G. Mirsky, "Common
            Interval Support in Bidirectional Forwarding Detection",
            RFC 7419, DOI 10.17487/RFC7419, December 2014,
            <http://www.rfc-editor.org/info/rfc7419>.
 [RFC7487]  Bellagamba, E., Takacs, A., Mirsky, G., Andersson, L.,
            Skoldstrom, P., and D. Ward, "Configuration of Proactive
            Operations, Administration, and Maintenance (OAM)
            Functions for MPLS-Based Transport Networks Using RSVP-
            TE", RFC 7487, DOI 10.17487/RFC7487, March 2015,
            <http://www.rfc-editor.org/info/rfc7487>.

Acknowledgements

 The authors would like to thank Nobo Akiya, David Allan, and Adrian
 Farrel for their thorough reviews and insightful comments.

Bellagamba, et al. Standards Track [Page 28] RFC 7759 Extensions for MPLS-TP OAM Config. February 2016

Authors' Addresses

 Elisa Bellagamba
 Email: elisa.bellagamba@gmail.com
 Gregory Mirsky
 Ericsson
 Email: Gregory.Mirsky@ericsson.com
 Loa Andersson
 Huawei Technologies
 Email: loa@mail01.huawei.com
 Pontus Skoldstrom
 Acreo AB
 Electrum 236
 Kista  164 40
 Sweden
 Phone: +46 8 6327731
 Email: pontus.skoldstrom@acreo.se
 Dave Ward
 Cisco
 Email: dward@cisco.com
 John Drake
 Juniper
 Email: jdrake@juniper.net

Bellagamba, et al. Standards Track [Page 29]

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