Operations and Management Area Working Group                  T. Mizrahi
Internet Draft                                                   Marvell
Intended status: Informational                               N. Sprecher
Expires: July 2013 January 2014                             Nokia Siemens Networks
                                                           E. Bellagamba
                                                                Ericsson
                                                           Y. Weingarten

                                                         January

                                                            July 9, 2013

                              An Overview of
        Operations, Administration, and Maintenance (OAM) Mechanisms
                   draft-ietf-opsawg-oam-overview-08.txt
                   draft-ietf-opsawg-oam-overview-09.txt

Abstract

   Operations, Administration, and Maintenance (OAM) is a general term
   that refers to a toolset that can be used for fault detection and isolation, and for
   performance measurement. OAM mechanisms have been defined for various
   layers in the protocol stack, and are used with a variety of
   transport protocols.

   This document presents an overview of the data plane OAM mechanisms tools that
   have been defined and are currently being defined by the IETF.

Status of this Memo

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   This Internet-Draft will expire on July January 9, 2013. 2014.

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Table of Contents

   1. Introduction ................................................. 3
      1.1. The Building Blocks of OAM .............................. 3 Background .............................................. 4
      1.2. Forwarding Plane vs. Management Plane ................... Target Audience.......................................... 4
      1.3. The OAM toolsets ........................................ 4
      1.4. OAM-related Work in the IETF ............................ 5
      1.4. Focusing on Data Plane OAM Documents ...................................... Tools ........................ 6
      1.5. Non-IETF OAM Documents ................................. 10
   2. Basic Terminology ........................................... 12 .................................................. 6
      2.1. Abbreviations .......................................... 12 ........................................... 6
      2.2. Terminology used in OAM Standards ...................... 13 ....................... 8
         2.2.1. General Terms ..................................... 13 ...................................... 8
         2.2.2. OAM Maintenance Entities .......................... 13 Functions, Mechanisms, Tools and Protocols ......... 8
         2.2.3. OAM Maintenance Points ............................ 14 Data Plane, Control Plane and Management Plane ..... 9
         2.2.4. The Players ....................................... 10
         2.2.5. Proactive and On-demand activation Activation ................ 15
         2.2.5. 11
         2.2.6. Connectivity Verification and Continuity Checks ... 15
         2.2.6. 11
         2.2.7. Failures .......................................... 15 12
   3. OAM Tools ................................................... 16
      3.1. Functions ............................................... 12
   4. OAM Mechanisms in the IETF - a Detailed Description.......... 13
      4.1. IP Ping and ................................................ 13
      4.2. IP Traceroute ................................. 16
         3.1.1. Ping .............................................. 16
         3.1.2. Traceroute......................................... 16
      3.2. .......................................... 14
      4.3. Bidirectional Forwarding Detection (BFD) ............... 17
         3.2.1. 15
         4.3.1. Overview .......................................... 17
         3.2.2. 15
         4.3.2. Terminology ....................................... 15
         4.3.3. BFD Control ....................................... 17
         3.2.3. 15
         4.3.4. BFD Echo .......................................... 18
      3.3. 16
      4.4. MPLS OAM ............................................... 18
      3.4. 16
      4.5. MPLS-TP OAM ............................................ 19
         3.4.1. 17
         4.5.1. Overview .......................................... 19
         3.4.2. 17
         4.5.2. Terminology ....................................... 17
         4.5.3. Generic Associated Channel ........................ 19
         3.4.3.
         4.5.4. MPLS-TP OAM Toolset ............................... 20
            3.4.3.1. 19
            4.5.4.1. Continuity Check and Connectivity Verification 20
            3.4.3.2.
            4.5.4.2. Route Tracing ................................ 21
            3.4.3.3. 20
            4.5.4.3. Lock Instruct ................................ 21
            3.4.3.4. 20
            4.5.4.4. Lock Reporting ............................... 21
            3.4.3.5.
            4.5.4.5. Alarm Reporting .............................. 21
            3.4.3.6.
            4.5.4.6. Remote Defect Indication ..................... 22
            3.4.3.7. 21
            4.5.4.7. Client Failure Indication .................... 22
            3.4.3.8. 21
            4.5.4.8. Performance Monitoring ....................... 21
               4.5.4.8.1. Packet Loss Measurement (LM) ................. ............ 22
            3.4.3.9.
               4.5.4.8.2. Packet Delay Measurement (DM) ................ ........... 22
      3.5. PWE3
      4.6. Pseudowire OAM ............................................... ......................................... 23
         3.5.1. PWE3
         4.6.1. Pseudowire OAM using Virtual Circuit Connectivity
         Verification (VCCV) ................................................... ...................................... 23
         3.5.2. PWE3
         4.6.2. Pseudowire OAM using G-ACh .............................. ........................ 24
         4.6.3. Attachment Circuit - Pseudowire Mapping ........... 24
      3.6.
      4.7. OWAMP and TWAMP......................................... 24
         3.6.1.
         4.7.1. Overview .......................................... 24
         3.6.2.
         4.7.2. Control and Test Protocols ........................ 24
         3.6.3. 25
         4.7.3. OWAMP ............................................. 25
         3.6.4.
         4.7.4. TWAMP ............................................. 26
      3.7.
      4.8. TRILL .................................................. 26
      4.9. Summary of OAM Mechanisms .............................. 27
      4.10. Summary of OAM Functions ............................... 26
   4. .............................. 29
   5. Security Considerations ..................................... 27
   5. 30
   6. IANA Considerations ......................................... 27
   6. 31
   7. Acknowledgments ............................................. 27
   7. 31
   8. References .................................................. 28
      7.1. Normative References ................................... 28
      7.2. 31
      8.1. Informative References ................................. 31
   Appendix A. List of OAM Documents .............................. 36
      A.1. List of IETF OAM Documents ............................. 36
      A.2. List of Selected Non-IETF OAM Documents ................ 41

1. Introduction

   OAM is a general term that refers to a toolset for detecting,
   isolating and reporting connection failures and performance
   degradation. for monitoring the network
   performance.

   There are several different interpretations to the "OAM" acronym.
   This document refers to Operations, Administration and Maintenance,
   as recommended in [OAM-Def].

   This document summarizes the OAM tools and mechanisms defined in the
   IETF.

   The term OAM in this This document refers to Operations, Administration
   and Maintenance [OAM-Def], focusing focuses on the forwarding data plane of OAM. OAM tools. Hence, control
   and management aspects of OAM are outside the scope of this document.

1.1. The Building Blocks of Background

   OAM

   An OAM protocol is run was originally used in traditional transport technologies such as
   E1 and T1, evolving into PDH and then later in SONET/SDH. ATM was
   probably the context of a Maintenance Domain,
   consisting of two or more nodes that run the OAM protocol, referred first technology to include inherent OAM mechanisms from
   day one, while in other transport technologies OAM was typically
   defined in an ad hoc manner after the technology was already defined
   and deployed. Packet-based networks were traditionally considered
   unreliable and best-effort, but as Maintenance Points (MP).

   This subsection provides a brief summary of packet-based networks evolved,
   they have become the common tools used by
   OAM transport for both data and telephony,
   replacing traditional transport protocols. An Consequently, packet-based
   networks were expected to provide a similar "carrier grade"
   experience, and specifically to support OAM.

   OAM protocol typically supports one or more has a multi-layer architecture; each transport
   technology has its own OAM mechanisms. Moreover, OAM can be used at
   different levels of hierarchy in the
   tools described below.

   o Continuity Checking (CC):
      Used for verifying network to form a multi-layer
   OAM solution, as shown in the liveness of example in Figure 1.

   Figure 1 illustrates a connection network in which IP traffic between two MPs.

   o Connectivity Verification (CV):
      Allows
   customer edges is transported over an MP to check whether it MPLS provider network. MPLS OAM
   is connected to a peer MP, and to
      verify that messages from the peer MP are received through the
      expected path.

   o Path Discovery / Fault Localization:
      An MP uses this mechanism to trace the route to a peer MP, i.e.,
      to identify the nodes along used at the path to provider-level for monitoring the peer MP. When a connection fails, this mechanism also allows the MP to detect between
   the
      location of two provider edges, while IP OAM is used at the failure.

   o Performance Monitoring:
      Consists of 3 main functions

        o Loss Measurement (LM) - monitors customer-level
   for monitoring the packet loss rate of a
          connection.

        o Delay Measurement (DM) - monitors end-to-end connection between the delay and delay
          variation between MPs. two customer
   edges.

           |<-------------- Customer-level OAM -------------->|
                 IP OAM (Ping, Traceroute, OWAMP, TWAMP)

                        |<- Provider-level OAM ->|
                            MPLS OAM (LSP Ping)

     +-----+       +----+                        +----+       +-----+
     |     |       |    |========================|    |       |     |
     |     |-------|    |          MPLS          |    |-------|     |
     |     |  IP   |    |                        |    |  IP   |     |
     +-----+       +----+                        +----+       +-----+
     Customer     Provider                      Provider      Customer
       Edge         Edge                          Edge          Edge

                     Figure 1 Example: Multi-layer OAM

1.2. Target Audience

   The target audience of this document includes:

   o Throughput measurement Standard development organizations - monitors the throughput of a
          connection.

1.2. Forwarding Plane vs. Management Plane

   While the OAM tools may, both IETF working groups and quite often do, work in conjunction with
   a control-plane
      non-IETF organizations can benefit from this document when
      designing new OAM protocols, or management plane, they are usually defined when looking to be
   independent of the control-plane.  The reuse existing OAM tools communicate with the
   management plane to raise alarms,
      mechanisms for new transport technologies.

   o Network equipment vendors and often the on-demand tools may
   be activated by the management, e.g. network operators - can use this
      document as an index to locate existing IETF OAM mechanisms, and localize problems.

   The considerations of the control-plane maintenance tools or the
   functionality of the management-plane are out of scope for this
   document, which will concentrate on presenting the forwarding-plane
   tools their
      connection to various transport technologies.

   It should be noted that are used this document is not necessarily suitable for
   beginners without any background in OAM.

1.3. The OAM toolsets OAM-related Work in the IETF

   This memo provides an overview of the different sets of OAM
   mechanisms defined by the IETF. It is intended for those with little
   or no familiarity with the described mechanisms. The set of OAM mechanisms described
   in this memo are applicable to IP unicast, MPLS, pseudowires, and MPLS
   for the transport environment (MPLS-TP). profile (MPLS-TP), and TRILL. While OAM mechanisms
   that are applicable to other technologies exist, they are beyond the
   scope of this memo.

   This document focuses on IETF documents that have been published as
   RFCs, while other ongoing OAM-
   related OAM-related work is outside the scope.

   The IETF has defined OAM protocols and mechanisms in several
   different fronts:

   o IP Ping and Traceroute:
      Ping is contexts. We roughly categorize these efforts into a very simple and common application for failure diagnosis
      that uses ICMP Echo requests, as defined few
   sets of OAM-related RFCs, listed in Table 1. Each category defines a
   logically-coupled set of RFCs, although the sets are in [ICMPv4], some cases
   intertwined by common tools and
      [ICMPv6].
      Traceroute ([TCPIP-Tools], [NetTools]) protocols.

   The discussion in this document is an application that
      allows users ordered according to trace the path between an IP source and an IP
      destination, i.e., to identify the nodes along the path.

   o BFD:
      Bidirectional Forwarding Detection (BFD) is defined in [BFD] as a
      framework for a lightweight these
   categories.

                     +--------------+------------+
                     | Category     | Transport  |
                     |              | Technology |
                     +--------------+------------+
                     |IP Ping       | IPv4/IPv6  |
                     +--------------+------------+
                     |IP Traceroute | IPv4/IPv6  |
                     +--------------+------------+
                     |BFD           | generic    |
                     +--------------+------------+
                     |MPLS OAM mechanism.  The intention
      is to define a base mechanism that can be used with various
      encapsulation types, network environments, and in various medium
      types.

   o MPLS OAM:      | MPLS LSP Ping, as defined in [MPLS-OAM], [MPLS-OAM-FW] and [LSP-
      Ping], is an       |
                     +--------------+------------+
                     |MPLS-TP OAM mechanism for point to point MPLS LSPs. It
      includes two main functions: Ping and Traceroute.

   o MPLS-TP OAM:   | MPLS-TP    |
                     +--------------+------------+
                     |Pseudowire OAM| Pseudowires|
                     +--------------+------------+
                     |OWAMP and     | IPv4/IPv6  |
                     |TWAMP         |            |
                     +--------------+------------+
                     |TRILL OAM is defined     | TRILL      |
                     +--------------+------------+
              Table 1 Categories of OAM-related IETF Documents

1.4. Focusing on Data Plane OAM Tools

   OAM tools may, and quite often do, work in conjunction with a set of RFCs. control
   plane and/or management plane.  The OAM requirements for
      MPLS Transport Profile (MPLS-TP) are defined in [MPLS-TP-OAM].
      Each of the tools in communicate with the
   management plane to raise alarms, and often OAM toolset is defined in its own RFC, tools may be
   activated by the management (as well as
      specified in Section 1.4.

   o PWE3 OAM: by the control plane), e.g.
   to locate and localize problems.

   The PWE3 OAM architecture defines considerations of the control channels that support plane maintenance tools and the use
   functionality of existing IETF OAM the management plane are out of scope for this
   document, which concentrates on presenting the data plane tools to be that
   are used for a pseudowire
      (PW).  The control channels that OAM.

   Since OAM protocols are defined in [VCCV] and [PW-G-
      ACH] may be used in conjunction with ICMP Ping, LSP Ping, and BFD
      to perform CC and CV functionality.  In addition the channels
      support use of any of for monitoring the MPLS-TP based data plane, it is
   imperative for OAM tools for completing
      their respective to be capable of testing the actual data
   plane in as much accuracy as possible. Thus, it is important to
   enforce fate-sharing between OAM functionality for a PW.

   o OWAMP traffic and TWAMP:
      The One Way Active the user-traffic it
   monitors.

2. Terminology

2.1. Abbreviations

   ACH    Associated Channel Header

   AIS    Alarm Indication Signal

   ATM    Asynchronous Transfer Mode

   BFD    Bidirectional Forwarding Detection

   CC     Continuity Check

   CV     Connectivity Verification
   DM     Delay Measurement

   FEC    Forwarding Equivalence Class

   G-ACh   Generic Associated Channel

   GAL    Generic Associated Label

   ICMP   Internet Control Message Protocol (OWAMP) and the

   L2TP   Layer Two Way
      Active Tunneling Protocol

   LCCE   L2TP Control Connection Endpoint

   LDP    Label Distribution Protocol

   LER    Label Edge Router

   LM     Loss Measurement Protocols (TWAMP) are two protocols defined in
      the IP Performance Metrics (IPPM) working group in the IETF. These
      protocols allow delay

   LSP    Label Switched Path

   LSR    Label Switched Router

   ME     Maintenance Entity

   MEG    Maintenance Entity Group

   MEP    MEG End Point

   MIP    MEG Intermediate Point

   MP     Maintenance Point

   MPLS   Multiprotocol Label Switching

   MPLS-TP MPLS Transport Profile

   MTU    Maximum Transmission Unit

   OAM    Operations, Administration, and packet loss measurement Maintenance

   PDH    Plesiochronous Digital Hierarchy

   PE     Provider Edge

   PW     Pseudowire
   PWE3   Pseudowire Emulation Edge-to-Edge

   RBridge Routing Bridge

   RDI    Remote Defect Indication

   SDH    Synchronous Digital Hierarchy

   SONET   Synchronous Optical Networking

   TRILL   Transparent Interconnection of Lots of Links

   TTL    Time To Live

   VCCV   Virtual Circuit Connectivity Verification

2.2. Terminology used in IP networks.

   This document summarizes the OAM mechanisms defined by the IETF. We
   first present Standards

2.2.1. General Terms

   A wide variety of terms is used in various OAM standards. This
   section presents a comparison of the terminology terms used in various OAM
   standards, and then summarize without fully quoting the OAM functions that definition of each term.

   An interesting overview of the term OAM
   standard provides.

1.4. IETF OAM Documents

   Table 1 summarizes and its derivatives is
   presented in [OAM-Def]. A thesaurus of terminology for MPLS-TP terms
   is presented in [TP-Term], and provides a good summary of some of the IETF
   OAM related RFCs discussed in this
   document.

   The table includes terminology.

2.2.2. Functions, Mechanisms, Tools and Protocols

OAM Function

   OAM is a "Type" column, specifying the nature group of each functions that provide network fault indication,
   performance information, and data and diagnosis functions (based on
   the definition of OAM in the listed documents:

   o Tool: documents ATM Forum Glossary).

   This definition implies that define OAM functions are the atomic building
   blocks of OAM, where each function defines an OAM tool or mechanism.

   o Prof.: documents that define a profile or a variant capability.

   Typical examples of OAM functions are presented in Section 3.

OAM Protocol

   A protocol used for implementing one or more OAM functions.

   The OWAMP-Test [OWAMP] is an example of an OAM
      tool that protocol.

OAM Mechanism

   An OAM Mechanism, sometimes referred to as an OAM tool, is defined in other documents.

   o Inf.: documents a
   mechanism that define implements one or more OAM functions.

   In some cases an infrastructure that is used by OAM
      tools.

   o Misc.: other protocol *is* an OAM related documents, mechanism, e.g., OWAMP-
   Test. In other cases an OAM requirement mechanism uses a set of protocols that
   are not strictly OAM-related; for example, Traceroute (Section 4.2.)
   can be implemented using UDP and
      framework documents.

   +-----------+--------------------------------------+-----+----------+
   |           | Title                                |Type | RFC      |
   +-----------+--------------------------------------+-----+----------+
   |IP Ping and| Internet Control Message Protocol    |Tool | RFC 792  |
   |Traceroute | [ICMPv4]                             |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Internet ICMP messages, without using an OAM
   protocol per se.

   The terms tool and mechanism are used interchangeably in this
   document.

2.2.3. Data Plane, Control Message Protocol    |Tool | RFC 4443 |
   |           | (ICMPv6) Plane and Management Plane

Data Plane

   The Data Plane is typically described as the hardware and software
   components responsible for receiving a packet, performing lookups to
   identify the Internet Protocol   |     | packet's destination and possible actions that need to
   be performed on the packet, and forwarding the packet out through the
   appropriate outgoing interface (based on [Cont]).

   The Data Plane is also known as the Forwarding Plane or the User
   Plane.

Control Plane

   The Control Plane, as described in [Cont], is generally described as
   the hardware and software components for handling packets destined to
   the device itself as well as building and sending packets originated
   locally on the device.

Management Plane

   This term Management Plane, as described in [Mgmt], is used to
   describe the exchange of management messages through management
   protocols (often transported by IP and by IP transport protocols)
   between management applications and the managed entities such as
   network nodes.

Data Plane vs. Control Plane vs. Management Plane

   The distinction between the planes is at times a bit vague. For
   example, the definition of "Control Plane" above may imply that OAM
   tools such as ping, BFD and others are in fact in the control plane.

   This document focuses on data plane OAM tools, i.e., tools used for
   monitoring the data plane. While these tools could arguably be
   considered to be in the control plane, these tools monitor the data
   plane, and hence it is imperative to have fate-sharing between OAM
   traffic and the data plane traffic it monitors.

   Another potentially vague distinction is between the management plane
   and control plane. The management plane should be seen as separate
   from, but possibly overlapping with, the control plane (based on
   [Mgmt]).

2.2.4. The Players

   An OAM mechanism is used between two (or more) "players". Various
   terms are used in IETF documents to refer to the players that take
   part in OAM. Table 2 summarizes the terms used in each of the
   categories discussed in this document.

          +--------------------------+--------------------------+
          | Category                 | Terms                    | Version 6 (IPv6) Specification
          +--------------------------+--------------------------+
          | Ping / Traceroute        |-Host                     |
          | ([ICMPv4], [ICMPv6],     |-Node                     |
          | [ICMPv6]  [TCPIP-Tools])          |-Interface                |
          |                          |-Gateway                  |
          + ------------------------ + ------------------------ +
          |           +--------------------------------------+-----+----------+ BFD [BFD]                | System                   | A Primer On Internet and TCP/IP      |Tool | RFC 2151 |
          + ------------------------ + ------------------------ +
          | MPLS OAM [MPLS-OAM-FW]   | Tools and Utilities [TCPIP-Tools] LSR                      |
          + ------------------------ + ------------------------ +
          | MPLS-TP OAM [TP-OAM-FW]  |-End Point - MEP          |
          |           +--------------------------------------+-----+----------+                          |-Intermediate Point - MIP |
          + ------------------------ + ------------------------ +
          | FYI on a Network Management Tool     |Tool Pseudowire OAM [VCCV]    |-PE                       | RFC 1147
          |                          |-LCCE                     |
          + ------------------------ + ------------------------ +
          | Catalog: Tools for Monitoring OWAMP and TWAMP          |-Host                     |
          | ([OWAMP], [TWAMP])       |-End system               |
          + ------------------------ + ------------------------ +
          | TRILL OAM [TRILL-OAM]    |-RBridge                  | Debugging TCP/IP Internets
          +--------------------------+--------------------------+
                   Table 2 Maintenance Point Terminology

2.2.5. Proactive and       |     |          |
   |           | Interconnected Devices [NetTools]    |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Extended ICMP to Support Multi-Part  |Tool | RFC 4884 |
   |           | Messages [ICMP-MP]                   |     |          |
   |           +--------------------------------------+-----+----------+
   |           | ICMP Extensions for Multiprotocol    |Tool | RFC 4950 |
   |           | Label Switching [ICMP-Ext]           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Extending ICMP for Interface On-demand Activation

   The different OAM tools may be used in one of two basic types of
   activation:

Proactive

   Proactive activation - indicates that the tool is activated on a
   continual basis, where messages are sent periodically, and     |Tool | RFC 5837 |
   |           | Next-Hop Identification [ICMP-Int]   |     |          |
   +-----------+--------------------------------------+-----+----------+
   |BFD        | Bidirectional Forwarding Detection   |Tool | RFC 5880 |
   |           | [BFD]                                |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Bidirectional Forwarding Detection   |Prof.| RFC 5881 |
   |           | (BFD) for IPv4 errors are
   detected when a certain number of expected messages are not received.

On-demand

   On-demand activation - indicates that the tool is activated
   "manually" to detect a specific anomaly.

2.2.6. Connectivity Verification and IPv6 (Single Hop) |     |          |
   |           | [BFD-IP]                             |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Generic Application Continuity Checks

   Two distinct classes of Bidirectional |Misc.| RFC 5882 |
   |           | Forwarding Detection [BFD-Gen]       |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Bidirectional Forwarding Detection   |Prof.| RFC 5883 |
   |           | (BFD) for Multihop Paths [BFD-Multi] |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Bidirectional Forwarding Detection   |Prof.| RFC 5884 |
   |           | for MPLS Label Switched Paths (LSPs) |     |          |
   |           | [BFD-LSP]                            |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Bidirectional Forwarding Detection   |Prof.| RFC 5885 |
   |           | for the Pseudowire Virtual Circuit   |     |          |
   |           | Connectivity Verification (VCCV)     |     |          |
   |           | [BFD-VCCV]                           |     |          |
   +-----------+--------------------------------------+-----+----------+
   |MPLS failure management functions are used in OAM   | Operations and Management (OAM)      |Misc.| RFC 4377 |
   |           | Requirements for Multi-Protocol Label|     |          |
   |           | Switched (MPLS) Networks [MPLS-OAM]  |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A Framework for Multi-Protocol       |Misc.| RFC 4378 |
   |           | Label Switching (MPLS) Operations    |     |          |
   |           |
   protocols, connectivity verification and Management (OAM) [MPLS-OAM-FW]   |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Detecting Multi-Protocol Label       |Tool | RFC 4379 |
   |           | Switched (MPLS) Data Plane Failures  |     |          |
   |           | [LSP-Ping]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Operations continuity checks. The
   distinction between these terms is defined in [MPLS-TP-OAM], and Management (OAM)      |Misc.| RFC 4687 |
   |           | Requirements for Point-to-Multipoint |     |          |
   |           | MPLS Networks [MPLS-P2MP]            |     |          |
   +-----------+--------------------------------------+-----+----------+
   |MPLS-TP    | Requirements for OAM is
   used similarly in MPLS-TP      |Misc.| RFC 5860 |
   |OAM        | [MPLS-TP-OAM]                        |     |          |
   |           +--------------------------------------+-----+----------+
   |           | MPLS Generic Associated Channel      |Inf. | RFC 5586 |
   |           | [G-ACh]                              |     |          |
   |           +--------------------------------------+-----+----------+
   |           | MPLS-TP OAM Framework                |Misc.| RFC 6371 |
   |           | [TP-OAM-FW]                          |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Proactive Connectivity Verification, |Tool | RFC 6428 |
   |           | this document.

Continuity Check, and Remote Defect  |     |          |
   |           | Indication for the MPLS Transport    |     |          |
   |           | Profile [TP-CC-CV]                   |     |          |
   |           +--------------------------------------+-----+----------+
   |           | MPLS On-Demand Connectivity          |Tool | RFC 6426 |
   |           | Verification and Route Tracing       |     |          |
   |           | [OnDemand-CV]                        |     |          |
   |           +--------------------------------------+-----+----------+
   |           | MPLS Fault Management Operations,    |Tool | RFC 6427 |
   |           | Administration, and Maintenance (OAM)|     |          |
   |           | [TP-Fault]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | MPLS Transport Profile Lock Instruct |Tool | RFC 6435 |
   |           | and Loopback Functions [Lock-Loop]   |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Packet Loss and Delay Measurement for|Tool | RFC 6374 |
   |           | MPLS Networks [MPLS-LM-DM]           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A Packet Loss Check

   Continuity checks are used to verify that a destination is reachable,
   and Delay Measurement  |Prof.| RFC 6375 |
   |           | Profile for MPLS-Based Transport     |     |          |
   |           | Networks [TP-LM-DM]                  |     |          |
   +-----------+--------------------------------------+-----+----------+
   |PWE3 OAM   | Pseudowire Virtual Circuit           |Inf. | RFC 5085 |
   |           | are typically sent proactively, though they can be invoked on-
   demand as well.

Connectivity Verification (VCCV):    |     |          |
   |           |

   A Control Channel for Pseudowires    |     |          |
   |           | [VCCV]                               |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Bidirectional Forwarding Detection   |Prof.| RFC 5885 |
   |           | for connectivity verification function allows Alice to check whether
   she is connected to Bob or not. This function also allows Alice to
   verify that messages from Bob are received through the Pseudowire Virtual Circuit   |     |          |
   |           | Connectivity Verification (VCCV)     |     |          |
   |           | [BFD-VCCV]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Using correct path,
   thereby verifying not only that the Generic Associated Channel |Inf. | RFC 6423 |
   |           | Label for Pseudowire in two MPs are connected, but also
   that they are connected through the MPLS     |     |          |
   |           | Transport Profile (MPLS-TP)          |     |          |
   |           | [PW-G-ACh]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Pseudowire (PW) Operations,          |Misc.| RFC 6310 |
   |           | Administration, and Maintenance (OAM)|     |          |
   |           | Message Mapping [PW-Map]             |     |          |
   +-----------+--------------------------------------+-----+----------+
   |OWAMP and  | A One-way Active Measurement Protocol|Tool | RFC 4656 |
   |TWAMP      | [OWAMP]                              |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A Two-Way Active Measurement Protocol|Tool | RFC 5357 |
   |           | [TWAMP]                              |     |          |
   |           +--------------------------------------+-----+----------+
   |           | Framework for IP Performance Metrics |Misc.| RFC 2330 |
   |           | [IPPM-FW]                            |     |          |
   |           +--------------------------------------+-----+----------+
   |           | IPPM Metrics for Measuring           |Misc.| RFC 2678 |
   |           | Connectivity [IPPM-Con]              |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A One-way Delay Metric for IPPM      |Misc.| RFC 2679 |
   |           | [IPPM-1DM]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A One-way Packet Loss Metric for IPPM|Misc.| RFC 2680 |
   |           | [IPPM-1LM]                           |     |          |
   |           +--------------------------------------+-----+----------+
   |           | A Round-trip Delay Metric for IPPM   |Misc.| RFC 2681 |
   |           | [IPPM-2DM]                           |     |          |
   +-----------+--------------------------------------+-----+----------+
                 Table 1 Summary expected path, allowing detection
   of IETF OAM Related RFCs

1.5. Non-IETF OAM Documents

   In addition to unexpected topology changes. It is noted that while the OAM mechanisms defined by CV
   function is performed in the IETF, data plane, the IEEE and
   ITU-T have also defined various OAM mechanisms "expected path" is
   predetermined either in the control plane or in the management plane.
   A connectivity verification (CV) protocol typically uses a CV
   message, followed by a CV reply that focus on
   Ethernet, is sent back to the originator.
   A CV function can be applied proactively or on-demand.

   Connectivity verification and various other transport network environments. These
   various continuity checks are considered
   complementary mechanisms, defined by the three standard organizations, and are often tightly coupled, and have had a mutual effect on used in conjunction with each
   other.

2.2.7. Failures

   The ITU-T and IETF have both defined OAM mechanisms for MPLS LSPs,
   [ITU-T-Y1711] and [LSP-Ping]. The following OAM standards by the IEEE terms Failure, Fault, and ITU-T Defect are used interchangeably in the
   standards, referring to a malfunction that can be detected by a
   connectivity or a continuity check. In some extent linked standards, such as
   802.1ag [IEEE802.1Q] , there is no distinction between these terms,
   while in other standards each of these terms refers to a different
   type of malfunction.

   The terminology used in IETF MPLS-TP OAM mechanisms listed
   above and are mentioned here only as reference material:

   o OAM mechanisms for Ethernet based networks have been defined by
      both the ITU-T in [ITU-T-Y1731], and by takes after the IEEE ITU-T, which
   distinguishes between these terms in [IEEE802.1ag]. [ITU-T-G.806];

Fault

   The IEEE 802.3 standard defines OAM for one-hop Ethernet links
      [IEEE802.3ah].

   o term Fault refers to an inability to perform a required action,
   e.g., an unsuccessful attempt to deliver a packet.

Defect

   The ITU-T has defined OAM for MPLS LSPs in [ITU-T-Y1711], and
      MPLS-TP OAM term Defect refers to an interruption in the normal operation,
   such as a consecutive period of time where no packets are delivered
   successfully.

Failure

   The term Failure refers to the termination of the required function.
   While a Defect typically refers to a limited period of time, a
   failure refers to a long period of time.

3. OAM Functions

   This subsection provides a brief summary of the common OAM functions
   used in OAM-related standards. These functions are used as building
   blocks in [ITU-G8113.1] and [ITU-G8113.2].

   Table 2 summarizes the OAM standards mentioned described in this document.

   o Connectivity Verification (CV) and/or Continuity Checks (CC):
      As defined in Section 2.2.6.

   o Path Discovery / Fault Localization:
      This
   document focuses on IETF OAM standards, but these non-IETF standards
   are referenced where relevant.

   +-----------+--------------------------------------+---------------+
   |           | Title                                |Standard/Draft |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | Operation & Maintenance mechanism    | ITU-T Y.1711  |
   |MPLS OAM   | for MPLS networks [ITU-T-Y1711]      |               |
   |           +--------------------------------------+---------------+
   |           | Assignment can be used to trace the route to a destination,
      i.e., to identify the nodes along the route to the destination.
      When more than one route is available to a specific destination,
      this mechanism traces one of the 'OAM Alert Label'  | RFC 3429      |
   |           | for Multiprotocol Label Switching    |               |
   |           | Architecture (MPLS) Operation and    |               |
   |           | Maintenance (OAM) Functions          |               |
   |           | [OAM-Label]                          |               |
   |           |                                      |               |
   |           |  Note: although available routes. When a failure
      occurs, this mechanism also allows to detect the location of the
      failure.
      Note that the term route tracing (or Traceroute) that is an IETF      |               |
   |           |  document, it used in
      the context of IP and MPLS, is listed sometimes referred to as one of the|               |
   |           |  non-IETF OAM standards, since it    |               |
   |           |  was defined path
      tracing in other transport technologies, such as a complementary part |               |
   |           |  of ITU-T Y.1711.                    |               |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | Operations, administration and       |ITU-T G.8113.2 |
   |MPLS-TP OAM| Maintenance mechanisms for MPLS-TP   |               |
   |           | networks using TRILL.

   o Performance Monitoring:
      Typically refers to:

        o Loss Measurement (LM) - monitors the tools defined for |               |
   |           | MPLS [ITU-G8113.2]                   |               |
   |           |                                      |               |
   |           |  Note: this document describes packet loss rate.

        o Delay Measurement (DM) - monitors the   |               |
   |           | delay and delay
          variation.

4. OAM toolset defined by Mechanisms in the IETF for |               |
   |           |  MPLS-TP, whereas ITU-T G.8113.1     |               |
   |           |  describes the OAM toolset defined   |               |
   |           |  by - a Detailed Description

   This section presents a detailed description of the ITU-T.                       |               |
   |           +--------------------------------------+---------------+
   |           | Operations, Administration and       |ITU-T G.8113.1 |
   |           | Maintenance mechanism for MPLS-TP sets of OAM-
   related mechanisms in |               |
   |           | Packet Transport Network (PTN)       |               |
   |           +--------------------------------------+---------------+
   |           | Allocation each of the categories in Table 1.

4.1. IP Ping

   Ping is a Generic Associated   | RFC 6671      |
   |           | Channel Type common network diagnosis application for ITU-T MPLS Transport|               |
   |           | Profile Operation, Maintenance, and  |               |
   |           | Administration (MPLS-TP OAM)         |               |
   |           | [ITU-T-CT]                           |               |
   |           |                                      |               |
   |           |  Note: although this IP networks that
   uses ICMP. 'Ping' is an IETF      |               |
   |           |  document, abbreviation for Packet internet groper
   [NetTerms].  As defined in [NetTerms], it is listed as one a program used to test
   reachability of the|               |
   |           |  non-IETF OAM standards, since it    |               |
   |           |  was defined as a complementary part |               |
   |           |  of ITU-T G.8113.1.                  |               |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | OAM Functions destinations by sending them an ICMP echo request and Mechanisms
   waiting for     |[ITU-T-Y1731]  |
   |Ethernet   | Ethernet-based Networks              |               |
   |OAM        |                                      |               |
   +-----------+--------------------------------------+---------------+
   |IEEE       | Connectivity Fault Management        | IEEE 802.1ag  |
   |CFM        | [IEEE802.1ag]                        |               |
   |           |                                      |               |
   |           |  Note: CFM was originally published  |               |
   |           | a reply.

   The ICMP Echo request/reply exchange in Ping is used as IEEE 802.1ag, but a continuity
   check function for the Internet Protocol. The originator transmits an
   ICMP Echo request packet, and the receiver replies with an Echo
   reply. ICMP ping is now         |               |
   |           |  incorporated defined in the 802.1Q standard.|               |
   +-----------+--------------------------------------+---------------+
   |IEEE       | Media Access Control Parameters,     | IEEE 802.3ah  |
   |802.3      | Physical Layers, two variants, [ICMPv4] is used for
   IPv4, and Management      |               |
   |link level | Parameters [ICMPv6] is used for Subscriber Access     |               |
   |OAM        | Networks [IEEE802.3ah]               |               |
   |           |                                      |               |
   |           |  Note: link level OAM was originally |               |
   |           |  defined IPv6.

   Ping implementations typically use ICMP messages. UDP Ping is a
   variant that uses UDP messages instead of ICMP echo messages.

   Ping is a single-ended continuity check, i.e., it allows the
   *initiator* of the Echo request to test the reachability. If it is
   desirable for both ends to test the reachability, both ends have to
   invoke Ping independently.

   Note that since ICMP filtering is deployed in IEEE 802.3ah, some routers and
   firewalls, the usefulness of Ping is now |               |
   |           |  incorporated sometimes limited in the 802.3 standard. |               |
   +-----------+--------------------------------------+---------------+
         Table 2 Non-IETF OAM Standards Mentioned in this Document

2. Basic Terminology

2.1. Abbreviations

   ACH    Associated Channel Header

   AIS    Alarm Indication Signal

   BFD    Bidirectional Forwarding Detection

   CC     Continuity Check

   CV     Connectivity Verification

   DM     Delay Measurement

   FEC    Forwarding Equivalence Class

   GAL    Generic Associated Label

   ICMP   Internet Control Message Protocol

   LDP    Label Distribution Protocol

   LM     Loss Measurement

   LSP    Label Switched Path

   ME     Maintenance Entity

   MEG    Maintenance Entity Group

   MEP    MEG End Point

   MIP    MEG Intermediate Point

   MP     Maintenance Point

   MPLS   Multiprotocol Label Switching
   MPLS-TP MPLS Transport Profile

   MTU    Maximum Transmission Unit

   OAM    Operations, Administration, and Maintenance

   PW     Pseudowire

   PWE3   Pseudowire Emulation Edge-to-Edge

   RDI    Remote Defect Indication

   TTL    Time To Live

   VCCV   Virtual Circuit Connectivity Verification

2.2. Terminology used in OAM Standards

2.2.1. General Terms

   A wide variety of terms wider
   internet. This limitation is used in various OAM standards. Each of the
   OAM standards listed in the reference section includes a section that
   defines terms equally relevant to that tool. A thesaurus of terminology for
   MPLS-TP terms Traceroute.

4.2. IP Traceroute

   Traceroute ([TCPIP-Tools], [NetTools]) is presented in [TP-Term], and provides a good summary
   of some of the OAM related terminology.

   This section presents an application that allows
   users to discover a comparison of the terms used in various OAM
   standards, without fully quoting the definition of each term. For path between an IP source and an IP destination.

   The most common way to implement Traceroute [TCPIP-Tools] is
   described as follows. Traceroute sends a
   formal definition sequence of each term, refer UDP packets to the references
   UDP port 33434 at the end destination. By default, Traceroute begins by
   sending three packets (the number of
   this document.

2.2.2. OAM Maintenance Entities

   OAM tools are designed to monitor and manage a Maintenance Entity
   (ME).  An ME, as defined packets is configurable in [TP-OAM-FW], defines a relationship
   between two points of a transport path to which maintenance and
   monitoring operations apply.

   The following related terms are also quoted from [TP-OAM-FW]:

   o MEP: The two points that define a maintenance entity.

   o MEG: The collection most
   Traceroute implementations), each with an IP Time-To-Live (or Hop
   Limit in IPv6) value of one or more MEs that belongs to the same
      transport path and that are maintained and monitored as a group
      are known as a Maintenance Entity Group (MEG).

   o MIP: In between MEPs, there are zero or more intermediate points,
      called Maintenance Entity Group Intermediate Points (MIPs).

   A pair of MEPs engaged in an ME are connected by a communication
   link, which may be one of several types of connection, e.g. a single
   physical connection, a set of physical connections, or a virtual link
   such as an MPLS LSP.

   The term Maintenance Entity (ME) is used in ITU-T Recommendations
   (e.g. [ITU-T-Y1731]), destination. These packets expire
   as well soon as they reach the first router in the MPLS-TP terminology ([TP-OAM-
   FW]). Various terms are used to refer to an ME. For example, BFD does
   not explicitly use a term path. Consequently,
   that is equivalent to ME, but rather uses
   the term "session", referring router sends three ICMP Time Exceeded Messages back to the relationship between two nodes
   using a BFD protocol. The MPLS LSP Ping ([LSP-Ping]) terminology
   simply uses
   Traceroute application. Traceroute now sends another three UDP
   packets, each with the term "LSP" in this context.

   MPLS-TP has defined TTL value of 2. These messages cause the terms ME and Maintenance Entity Group (MEG)
   in [TP-OAM-FW], similar
   second router to the terms defined by ITU-T.  A MEG allows
   the monitoring of a compound set of MEs, return ICMP messages. This process continues, with
   ever increasing values for example when monitoring
   a p2mp MEG that is considered the TTL field, until the packets actually
   reach the destination. Because no application listens to be port 33434
   at the set of MEs between destination, the root
   and each individual destination MEP.

2.2.3. OAM Maintenance Points

   A Maintenance Point (MP) is a functional entity returns ICMP Destination
   Unreachable Messages indicating an unreachable port. This event
   indicates to the Traceroute application that it is defined at a
   node in finished.  The
   Traceroute program displays the network, and either initiates or reacts to OAM messages.
   A Maintenance End Point (MEP) is one round-trip delay associated with each
   of the end points of an ME, and
   can initiate OAM messages and respond to them. A Maintenance
   Intermediate Point (MIP) attempts.

   It is an intermediate point between two MEPs, noted that does not generally initiate OAM frames (one exception to this Traceroute is an application, and not a protocol. As
   such, it has various different implementations. One of the most
   common ones uses UDP probe packets, as described above. Other
   implementations exist that use other types of AIS notifications), but is able to respond to OAM frames probe messages, such as
   ICMP or TCP.

   Note that are destined to it. IP routing may be asymmetric. While Traceroute discovers a
   path between a source and destination, it does not reveal the reverse
   path.

   A MIP few ICMP extensions ([ICMP-MP], [ICMP-Int]) have been defined in MPLS-TP identifies OAM packets
   destined to it by
   the value context of Traceroute. These documents define several extensions,
   including extensions to the TTL field in the OAM packet. The
   term Maintenance Point is a general term for MEPs and MIPs.

   The 802.1ag defines a finer distinction between Up MPs and Down MPs.
   An MP is a bridge interface, ICMP Destination Unreachable message,
   that is monitored can be used by an Traceroute applications.

4.3. Bidirectional Forwarding Detection (BFD)

4.3.1. Overview

   While multiple OAM protocol
   either in the direction facing the network, or mechanisms have been defined for various protocols
   in the direction
   facing protocol stack, Bidirectional Forwarding Detection [BFD],
   defined by the bridge. A Down MP IETF BFD working group, is an MP that receives a generic OAM packets from, mechanism
   that can be deployed over various encapsulating protocols, and transmits them to the direction in
   various medium types. The IETF has defined variants of the network. An Up MP receives
   OAM packets from, protocol
   for IP ([BFD-IP], [BFD-Multi]), for MPLS LSPs [BFD-LSP], and transmits them to the direction for
   pseudowires [BFD-VCCV]. The usage of the bridging
   entity. BFD in MPLS-TP ([TP-OAM-FW]) uses a similar distinction on the placement of
   the MP - either at the ingress, egress, or forwarding function of the
   node (Down / Up MPs).  This placement is important for localization
   of a connection failure.

2.2.4. Proactive and On-demand activation

   The different OAM tools may be used defined in one of
   [TP-CC-CV].

   BFD includes two main OAM functions, using two basic types of
   activation:

   o Proactive activation - indicates that the tool BFD packets:
   BFD Control packets, and BFD Echo packets.

4.3.2. Terminology

   BFD operates between two *systems*. The BFD protocol is activated on a
      continual basis periodically, where messages are sent run between the
   two MEPs, and errors are detected when systems after establishing a certain number of
      expected messages *session*.

4.3.3. BFD Control

   BFD supports a bidirectional continuity check, using BFD control
   packets, that are not received.

   o On-demand activation - indicates that the tool is activated
      "manually" to detect a specific anomaly.  In this activation exchanged within a
      small number BFD session. BFD sessions
   operate in one of OAM messages two modes:

   o Asynchronous mode (i.e. proactive): in this mode BFD control
      packets are sent by a MEP and periodically. When the reply
      message is received.

2.2.5. Connectivity Verification and Continuity Checks

   Two distinct classes receiver detects that no
      BFD control packets have been received during a predetermined
      period of time, a failure management functions are used in OAM
   protocols, connectivity verification and continuity checks. The
   distinction between these terms is defined in [MPLS-TP-OAM], and is
   used similarly detected.

   o Demand mode: in this document.

   Continuity checks mode, BFD control packets are used to verify the liveness of sent on-demand.
      Upon need, a connection or system initiates a path between two MPs, and are typically sent proactively, though
   they can be invoked on-demand as well.

   A connectivity verification function allows an MP series of BFD control packets to
      check whether it
   is connected to a peer MP or not. This function also allows the MP to
   verify that messages from continuity of the peer MP session. BFD control packets are received through sent
      independently in each direction.

   Each of the
   correct path, thereby verifying not only that end-points (referred to as systems) of the two MPs monitored path
   maintains its own session identification, called a Discriminator,
   both of which are
   connected, but also included in the BFD Control Packets that they are connected through
   exchanged between the expected
   path. This allows detection end-points.  At the time of unexpected topology changes. A
   connectivity verification (CV) protocol typically uses a CV message,
   followed by a CV reply that is sent back to session
   establishment, the originator. A CV
   function can be applied proactively or on-demand.

   Connectivity verification and continuity checks are considered
   complementary mechanisms, and are often used in conjunction with each
   other.

2.2.6. Failures

   The terms Failure, Fault, and Defect Discriminators are used interchangeably in exchanged between the
   standards, referring to a malfunction that can be detected by a
   connectivity or a continuity check. two-end
   points.  In some standards, such as
   [IEEE802.1ag], there addition, the transmission (and reception) rate is no distinction
   negotiated between these terms, while in
   other standards each of these terms refers to a different type of
   malfunction.

   The terminology used in IETF MPLS-TP OAM takes after the ITU-T, which
   distinguishes between these terms in [ITU-T-G.806]; The term Fault
   refers to an inability to perform a required action, e.g., an
   unsuccessful attempt to deliver a packet. The term Defect refers to
   an interruption two end-points, based on information included
   in the control packets.  These transmission rates may be renegotiated
   during the session.

   During normal operation, such as a consecutive period operation of time where the session, i.e. no packets failures are delivered successfully. The term Failure
   refers to
   detected, the termination of BFD session is in the required function. While a Defect
   typically refers to Up state.  If no BFD Control
   packets are received during a limited period of time, a failure refers time called the Detection
   Time, the session is declared to be Down. The detection time is a
   long period
   function of time.

3. OAM Tools

3.1. IP Ping the pre-configured or negotiated transmission time, and Traceroute

3.1.1. Ping

   Ping is a common network diagnosis application for IP networks that
   uses ICMP. The ICMP
   parameter called Detect Mult. Detect Mult determines the number of
   missing BFD Control packets that cause the session to be declared as
   Down. This parameter is included in the BFD Control packet.

4.3.4. BFD Echo request/reply exchange

   A BFD echo packet is sent to a connectivity
   verification function for peer system, and is looped back to the Internet Protocol.
   originator. The originator
   transmits an ICMP Echo request packet, echo function can be used proactively, or on-demand.

   The BFD echo function has been defined in BFD for IPv4 and the receiver replies with
   an Echo reply. ICMP ping IPv6
   ([BFD-IP]), but is not used in BFD for MPLS LSPs, PWs, or in BFD for
   MPLS-TP.

4.4. MPLS OAM

   The IETF MPLS working group has defined OAM for MPLS LSPs. The
   requirements and framework of this effort are defined in
   [MPLS-OAM-FW] and [MPLS-OAM], respectively. The corresponding OAM
   mechanism defined, in this context, is LSP Ping [LSP-Ping].

   LSP Ping is modeled after the Ping/Traceroute paradigm and thus it
   may be used in one of two variants, [ICMPv4] modes:

   o "Ping" mode: In this mode LSP Ping is used for IPv4, and [ICMPv6] end-to-end
      connectivity verification between two LERs.

   o "Traceroute" mode: This mode is used for IPv6.

3.1.2. Traceroute

   Traceroute ([TCPIP-Tools], [NetTools]) is an application that allows
   users to discover hop-by-hop fault
      isolation.

   LSP Ping extends the path between an IP source basic ICMP Ping operation (of data-plane
   connectivity verification) with functionality to verify data-plane
   vs. control-plane consistency for a Forwarding Equivalence Class
   (FEC) and an IP
   destination. also Maximum Transmission Unit (MTU) problems. The
   Traceroute sends a sequence of UDP packets functionality may be used to UDP port
   33434 at isolate and localize the destination. By default, Traceroute begins by sending
   three packets (the number MPLS
   faults, using the Time-to-live (TTL) indicator to incrementally
   identify the sub-path of packets the LSP that is configurable in most
   Traceroute implementations), each with successfully traversed
   before the faulty link or node.

   It should be noted that LSP Ping supports unique identification of
   the LSP within an IP Time-To-Live (TTL) value addressing domain. The identification is checked
   using the full FEC identification. LSP Ping is easily extensible to
   include additional information needed to support new functionality,
   by use of one Type-Length-Value (TLV) constructs. The usage of TLVs is
   typically not easy to perform in hardware, and is thus typically
   handled by the destination. These packets expire as soon control plane.

   LSP Ping supports both asynchronous, as they reach well as, on-demand
   activation.

4.5. MPLS-TP OAM

4.5.1. Overview

   The MPLS working group has defined the first router OAM toolset that fulfills the
   requirements for MPLS-TP OAM. The full set of requirements for MPLS-
   TP OAM are defined in [MPLS-TP-OAM], and include both general
   requirements for the path. That router responds behavior of the OAM mechanisms and a set of
   operations that should be supported by sending three
   ICMP Time Exceeded Messages to the Traceroute application. Traceroute
   now sends another three UDP packets, each with OAM toolset.  The set of
   mechanisms required are further elaborated in [TP-OAM-FW], which
   describes the TTL value general architecture of 2.
   These messages cause the second router to return ICMP messages. This
   process continues, with ever increasing values for OAM system as well as
   giving overviews of the TTL field,
   until functionality of the packets actually reach OAM toolset.

   Some of the destination. Because no
   application listens to port 33434 at the destination, basic requirements for the destination
   returns ICMP Destination Unreachable Messages indicating an
   unreachable port. This event indicates OAM toolset for MPLS-TP are:

   o MPLS-TP OAM must be able to support both an IP based and non-IP
      based environment. If the Traceroute application
   that it network is finished.  The Traceroute program displays IP based, i.e. IP routing and
      forwarding are available, then the round-trip
   delay associated with each of MPLS-TP OAM toolset should rely
      on the attempts.

   Note that IP routing may be asymmetric. While Traceroute reveals the
   path between a source and destination, it may not reveal forwarding capabilities. On the reverse
   path.

   A few ICMP extensions ([ICMP-Ext], [ICMP-MP], [ICMP-Int]) have been
   defined other hand,
      in environments where IP functionality is not available, the context of Traceroute. These extensions augment the
   ICMP Destination Unreachable message, and can OAM
      tools must still be used by Traceroute
   applications.

3.2. Bidirectional Forwarding Detection (BFD)

3.2.1. Overview

   While multiple able to operate without dependence on IP
      forwarding and routing.

   o OAM mechanisms have been defined for various protocols
   in the protocol stack, Bidirectional Forwarding Detection [BFD],
   defined by packets and the IETF BFD working group, user traffic are required to be congruent
      (i.e. OAM packets are transmitted in-band) and there is a generic need to
      differentiate OAM mechanism
   that can be deployed over various encapsulating protocols, and packets from data plane ones. Inherent in
   various medium types. The IETF has defined variants of this
      requirement is the protocol
   for IP ([BFD-IP], [BFD-Multi]), for MPLS LSPs [BFD-LSP], and for PWE3
   [BFD-VCCV]. The usage of BFD in principle that MPLS-TP is defined in [MPLS-TP-CC-
   CV].

   BFD includes two main OAM functions, using two types be independent of BFD packets:
   BFD Control packets, and BFD Echo packets.

3.2.2. BFD Control

   BFD supports a bidirectional continuity check, using BFD control
   packets, that
      any existing control-plane, although it should not preclude use of
      the control-plane functionality.

4.5.2. Terminology

Maintenance Entity (ME)

   The MPLS-TP OAM tools are exchanged within designed to monitor and manage a BFD session. BFD sessions
   operate in one of two modes:

   o Asynchronous mode (i.e. proactive):
   Maintenance Entity (ME).  An ME, as defined in this mode BFD control
      packets are sent periodically. When the receiver detects that no
      BFD control packet have been received during [TP-OAM-FW], defines a predetermined
      period
   relationship between two points of time, a failure transport path to which
   maintenance and monitoring operations apply.

   The term Maintenance Entity (ME) is detected.

   o Demand mode: used in this mode, BFD control packets are sent on-demand.
      Upon need, a system initiates a series of BFD control packets to
      verify the liveness of the session. BFD control packets are sent
      independently ITU-T Recommendations
   (e.g. [ITU-T-Y1731]), as well as in each direction.

   Each of the end-points MPLS-TP terminology
   ([TP-OAM-FW]).

Maintenance Entity Group (MEG)

   The collection of one or more MEs that belongs to the monitored same transport
   path maintains its own
   session identification, called and that are maintained and monitored as a Discriminator, both of which group are
   included in the BFD Control Packets known as a
   Maintenance Entity Group (based on [TP-OAM-FW]).

Maintenance Point (MP)

   A Maintenance Point (MP) is a functional entity that are exchanged between is defined at a
   node in the
   end-points.  At network, and can initiate and/or react to OAM messages.
   This document focuses on the time data-plane functionality of session establishment, the Discriminators
   are exchanged between the two-end points.  In addition, the
   transmission (and reception) rate is negotiated between the two end-
   points, based on information included in MPs, while
   MPs interact with the control packets.  These
   transmission rates may be renegotiated during the session.

   During normal operation of the session, i.e. no failures are
   detected, plane and with the BFD session management plane as
   well.

   The term MP is used in IEEE 802.1ag, and was similarly adopted in
   MPLS-TP ([TP-OAM-FW]).

Maintenance End Point (MEP)

   A Maintenance End Point (MEP) is one of the Up state.  If no BFD Control
   packets are received during a fixed period end points of time, an ME, and
   can initiate OAM messages and respond to them (based on [TP-OAM-FW]).

Maintenance Intermediate Point (MIP)

   In between MEPs, there are zero or more intermediate points, called the
   Detection Time, the session
   Maintenance Entity Group Intermediate Points  (based on [TP-OAM-FW]).

   A Maintenance Intermediate Point (MIP) is declared an intermediate point that
   does not generally initiate OAM frames (one exception to be Down. The detection
   time this is a function of the negotiated transmission time, and a
   parameter called Detect Mult. Detect Mult determines the number
   use of
   missing BFD Control packets AIS notifications), but is able to respond to OAM frames that cause the session
   are destined to be declared as
   Down. This parameter is included it. A MIP in MPLS-TP identifies OAM packets destined
   to it by the BFD Control value of the TTL field in the OAM packet.

3.2.3. BFD Echo

   A BFD echo packet The term
   Maintenance Point is sent to a peer system, general term for MEPs and is looped back to the
   originator. The echo function can be used proactively, or on-demand. MIPs.

Up and Down MEPs

   The BFD echo function has been defined in BFD for IPv4 IEEE 802.1ag [IEEE802.1Q] defines a distinction between Up MEPs
   and IPv6
   ([BFD-IP]), but Down MEPs. A MEP is not used a bridge interface that is monitored by an
   OAM protocol either in BFD for MPLS LSPs, PWs, the direction facing the network, or in BFD for
   MPLS-TP.

3.3. MPLS the
   direction facing the bridge. A Down MEP is a MEP that receives OAM

   The IETF MPLS working group has defined
   packets from, and transmits them to the direction of the network. An
   Up MEP receives OAM packets from, and transmits them to the direction
   of the bridging entity. MPLS-TP ([TP-OAM-FW]) uses a similar
   distinction on the placement of the MEP - either at the ingress,
   egress, or forwarding function of the node (Down / Up MEPs).  This
   placement is important for MPLS LSPs. localization of a failure.

   The
   requirements distinction between Up and framework Down MEPs was defined in [TP-OAM-FW],
   but has not been used in other MPLS-TP RFCs, as of the writing of
   this effort are document.

4.5.3. Generic Associated Channel

   In order to address the requirement for in-band transmission of MPLS-
   TP OAM traffic, MPLS-TP uses a Generic Associated Channel (G-ACh),
   defined in [MPLS-OAM-
   FW] and [MPLS-OAM], respectively. The corresponding [G-ACh] for LSP-based OAM traffic. This mechanism
   defined, in this context, is LSP Ping [LSP-Ping].

   LSP Ping is based
   on ICMP Ping the same concepts as the PWE3 ACH and just like its predecessor may be
   used in one VCCV mechanisms.  However,
   to address the needs of two modes: LSPs as differentiated from PW, the following
   concepts were defined for [G-ACh]:

   o "Ping" mode: In this mode LSP ping An Associated Channel Header (ACH), that uses a format similar to
      the PW Control Word, is used for end-to-end
      connectivity verification between two LERs.

   o "Traceroute" mode: This mode a 4-byte header that is used for hop-by-hop fault
      isolation.

   LSP Ping extends the basic ICMP Ping operation (of data-plane
   connectivity verification) with functionality prepended to verify data-plane
   vs. control-plane consistency for a Forwarding Equivalence Class
   (FEC) and also Maximum Transmission Unit (MTU) problems. OAM
      packets.

   o A Generic Associated Label (GAL). The
   traceroute functionality may be used to isolate and localize the GAL is a reserved MPLS
   faults, using the Time-to-live (TTL) indicator to incrementally
   identify the sub-path of the LSP label
      value (13) that indicates that the packet is successfully traversed
   before an ACH packet and the faulty link or node.
      payload follows immediately after the label stack.

   It should be noted that LSP Ping supports unique identification while the G-ACh was defined as part of the LSP within an addressing domain. The identification is checked
   using
   MPLS-TP definition effort, the full FEC identification. LSP Ping is easily extensible to
   include additional information needed to support new functionality,
   by use of Type-Length-Value (TLV) constructs. The usage of TLVs G-ACh is
   typically not easy to perform a generic tool that can be
   used in hardware, MPLS in general, and is thus typically
   handled by the control plane.

   LSP Ping supports both asynchronous, as well as, on-demand
   activation.

3.4. not only in MPLS-TP.

4.5.4. MPLS-TP OAM

3.4.1. Overview

   The MPLS working group Toolset

   To address the functionality that is currently working on defining required of the OAM
   toolset that fulfills toolset, the requirements for MPLS-TP OAM. The full set
   of requirements for MPLS-TP OAM are defined in [MPLS-TP-OAM], and
   include both general requirements for the behavior
   MPLS WG conducted an analysis of the existing IETF and ITU-T OAM
   mechanisms and a set of operations that should be supported by their ability to fulfill the
   OAM toolset. required functionality.
   The set conclusions of mechanisms required this analysis are further elaborated documented in [TP-OAM-FW], which describes the general architecture [OAM-Analys]. The
   MPLS working group currently plans to use a mixture of the OAM
   system as well as giving overviews of mechanisms
   that are based on various existing standards, and adapt them to the functionality
   requirements of the OAM
   toolset. [MPLS-TP-OAM]. Some of the basic requirements main building blocks of
   this solution are based on:

   o Bidirectional Forwarding Detection ([BFD], [BFD-LSP]) for the OAM toolset
      proactive continuity check and connectivity verification.

   o LSP Ping as defined in [LSP-Ping] for MPLS-TP are: on-demand connectivity
      verification.

   o MPLS-TP OAM must be able New protocol packets, using G-ACH, to support both an IP based and non-IP
      based environment. If the network is IP based, i.e. IP routing and
      forwarding address different
      functionality.

   o Performance measurement protocols that are available, then the MPLS-TP OAM toolset should rely based on the IP routing and forwarding capabilities. On the other hand,
      in environments where IP
      functionality that is not available, described in [ITU-T-Y1731].

   The following sub-sections describe the OAM tools must still be able to operate without dependence on IP
      forwarding defined for MPLS-TP
   as described in [TP-OAM-FW].

4.5.4.1. Continuity Check and routing.

   o OAM packets Connectivity Verification

   Continuity Check and the user traffic are required to be congruent
      (i.e. OAM packets Connectivity Verification are transmitted in-band) and there is a need to
      differentiate OAM packets from user-plane ones. Inherent presented in
   Section 2.2.6. of this
      requirement document.  As presented there, these tools may
   be used either proactively or on-demand.  When using these tools
   proactively, they are generally used in tandem.

   For MPLS-TP there are two distinct tools, the proactive tool is
   defined in [TP-CC-CV] while the principle that MPLS-TP OAM be independent of
      any existing control-plane, although it on-demand tool is defined in
   [OnDemand-CV]. In on-demand mode, this function should not preclude use of support
   monitoring between the control-plane functionality.

3.4.2. Generic Associated Channel

   In order to address MEPs and, in addition, between a MEP and MIP.
   [TP-OAM-FW] highlights,  when performing Connectivity Verification,
   the requirement need for in-band transmission the CC-V messages to include unique identification of MPLS-
   TP OAM traffic, MPLS-TP uses a Generic Associated Channel (G-ACh),
   defined in [G-ACh] for LSP-based OAM traffic. This mechanism
   the MEG that is being monitored and the MEP that originated the
   message.

   The proactive tool [TP-CC-CV] is based on extensions to BFD (see
   Section 4.3.) with the same concepts as additional limitation that the PWE3 ACH transmission
   and VCCV mechanisms.  However,
   to address receiving rates are based on configuration by the needs operator.  The
   on-demand tool [OnDemand-CV] is an adaptation of LSPs as differentiated from PW, the following
   concepts were defined LSP Ping (see
   Section 4.4.) for [G-ACh]:

   o An Associated Channel Header (ACH), that uses a format similar to the PW Control Word, is a 4-byte header required behavior of MPLS-TP.

4.5.4.2. Route Tracing

   [MPLS-TP-OAM] defines that is prepended to OAM
      packets.

   o A Generic Associated Label (GAL). The GAL there is a reserved MPLS label
      value (13) that indicates need for functionality that
   would allow a path end-point to identify the packet is an ACH packet intermediate and end-
   points of the
      payload follows immediately after the label stack.

3.4.3. MPLS-TP OAM Toolset

   To address path. This function would be used in on-demand mode.
   Normally, this path will be used for bidirectional PW, LSP, and
   sections, however, unidirectional paths may be supported only if a
   return path exists.  The tool for this is based on the LSP Ping (see
   Section 4.4.) functionality that and is required described in [OnDemand-CV].

4.5.4.3. Lock Instruct

   The Lock Instruct function [Lock-Loop] is used to notify a transport
   path end-point of an administrative need to disable the transport
   path.  This functionality will generally be used in conjunction with
   some intrusive OAM toolset, function, e.g. Performance measurement, Diagnostic
   testing, to minimize the
   MPLS WG conducted side-effect on user data traffic.

4.5.4.4. Lock Reporting

   Lock Reporting is a function used by an analysis end-point of a path to report
   to its far-end end-point that a lock condition has been affected on
   the existing IETF and ITU-T OAM
   mechanisms and their ability path.

4.5.4.5. Alarm Reporting

   Alarm Reporting [TP-Fault] provides the means to fulfill suppress alarms
   following detection of defect conditions at the required functionality.
   The conclusions server sub-layer.
   Alarm reporting is used by an intermediate point of this analysis are documented in [OAM-Analys]. The
   MPLS working group currently plans to use a mixture of OAM mechanisms path, that are based
   becomes aware of a fault on various existing standards, and adapt them the path, to report to the
   requirements of [MPLS-TP-OAM]. Some end-points of
   the main building blocks of path. [TP-OAM-FW] states that this solution are based on:

   o Bidirectional Forwarding Detection ([BFD], [BFD-LSP]) for
      proactive continuity check and connectivity verification.

   o LSP Ping may occur as defined in [LSP-Ping] for on-demand connectivity
      verification.

   o New protocol packets, using G-ACH, to address different
      functionality.

   o Performance measurement protocols a result of a
   defect condition discovered at a server sub-layer. This generates an
   Alarm Indication Signal (AIS) that are based on continues until the
      functionality that fault is described in [ITU-T-Y1731].
   cleared. The following sub-sections describe the OAM tools defined for MPLS-TP
   as described consequent action of this function is detailed in
   [TP-OAM-FW].

3.4.3.1. Continuity Check and Connectivity Verification

   Continuity Check and Connectivity Verification are presented in
   Section 2.2.5. of

4.5.4.6. Remote Defect Indication

   Remote Defect Indication (RDI) is used proactively by a path end-
   point to report to its peer end-point that a defect is detected on a
   bidirectional connection between them. [MPLS-TP-OAM] points out that
   this document.  As presented there, these tools function may be used either proactively or on-demand.  When using these tools
   proactively, they are generally used in tandem.

   For MPLS-TP applied to a unidirectional LSP only if there are two distinct tools, the proactive tool a
   return path exists.  [TP-OAM-FW] points out that this function is
   defined in [TP-CC-CV] while
   associated with the on-demand tool proactive CC-V function.

4.5.4.7. Client Failure Indication

   Client Failure Indication (CFI) is defined in

   [OnDemand-CV].Proactively [MPLS-TP-OAM] states that the function
   should to allow
   the MEPs propagation information from one edge of the network to monitor the liveness and connectivity of
   other. The information concerns a
   transport path. In on-demand mode, this function should defect to a client, in the case
   that the client does not support alarm notification.

4.5.4.8. Performance Monitoring

   The definition of MPLS performance monitoring between was motivated by the MEPs and,
   MPLS-TP requirements [MPLS-TP-OAM], but was defined generically for
   MPLS in addition, between [MPLS-LM-DM]. An additional document [TP-LM-DM] defines a MEP and MIP.
   [TP-OAM-FW] highlights,  when performing Connectivity Verification,
   the need
   performance monitoring profile for the CC-V messages MPLS-TP.

4.5.4.8.1. Packet Loss Measurement (LM)

   Packet Loss Measurement is a function used to include unique identification verify the quality of
   the MEG that is being monitored service. Packet loss, as defined in [IPPM-1LM] and [MPLS-TP-OAM],
   indicates the MEP that originated ratio of the
   message.

   The proactive tool [TP-CC-CV] is based on extensions number of user packets lost to BFD (see
   Section 3.2. ) with the additional limitation that the transmission
   and receiving rates total
   number of user packets sent during a defined time interval.

   There are two possible ways of determining this measurement:

   o Using OAM packets, it is possible to compute the statistics based
      on configuration by a series of OAM packets. This, however, has the operator.  The
   on-demand tool [OnDemand-CV] is an adaptation disadvantage of
      being artificial, and may not be representative since part of LSP Ping (see
   Section 3.3. ) for the required behavior
      packet loss may be dependent upon packet sizes and upon the
      implementation of MPLS-TP.

3.4.3.2. Route Tracing

   [MPLS-TP-OAM] defines the MEPs that there is a need take part in the protocol.

   o Sending delimiting messages for functionality that
   would allow the start and end of a path end-point to identify measurement
      period during which the intermediate source and end-
   points sink of the path. This function would be used in on-demand mode.
   Normally, this path will be used for bidirectional PW, LSP, count the
      packets transmitted and
   sections, however, unidirectional paths may received. After the end delimiter, the
      ratio would be supported only if a
   return calculated by the path exists.  The tool for this OAM entity.

4.5.4.8.2. Packet Delay Measurement (DM)

   Packet Delay Measurement is based on the LSP Ping (see
   Section 3.3. ) functionality and is described in [OnDemand-CV].

3.4.3.3. Lock Instruct

   The Lock Instruct a function [Lock-Loop] that is used to notify measure one-
   way or two-way delay of a transport
   path end-point packet transmission between a pair of an administrative need to disable the transport
   path.  This functionality will generally be used in conjunction with
   some intrusive OAM function, e.g. Performance measurement, Diagnostic
   testing, to minimize the side-effect on user data traffic.

3.4.3.4. Lock Reporting

   Lock Reporting is a function used by an end-point
   end-points of a path to report
   to its far-end end-point that a lock condition has been affected on
   the path.

3.4.3.5. Alarm Reporting

   Alarm Reporting (PW, LSP, or Section). Where:

   o One-way packet delay, as defined in [IPPM-1DM], is a function used by an intermediate point the time
      elapsed from the start of a
   path, that becomes aware transmission of a fault on the path, to report to first bit of the
   end-points
      packet by a source node until the reception of the path. [TP-OAM-FW] states last bit of
      that this may occur packet by the destination node.

   o Two-way packet delay, as a
   result defined in [IPPM-2DM], is the time
      elapsed from the start of transmission of the first bit of the
      packet by a defect condition discovered at a server sub-layer. This
   generates an Alarm Indication Signal (AIS) that continues source node until the
   fault reception of the last bit of the
      loop-backed packet by the same source node, when the loopback is cleared. The consequent action
      performed at the packet's destination node.

   For each of this these two metrics, the DM function is detailed
   in [TP-OAM-FW].

3.4.3.6. Remote Defect Indication

   Remote Defect Indication (RDI) is used proactively by a path end-
   point allows the MEP to report to its peer end-point that a defect
   measure the delay, as well as the delay variation. Delay measurement
   is detected on a
   bidirectional connection performed by exchanging timestamped OAM packets between them. [MPLS-TP-OAM] points out that
   this function may be applied to a unidirectional LSP only if there a
   return path exists.  [TP-OAM-FW] points out that this function is
   associated with the proactive CC-V function.

3.4.3.7. Client Failure Indication

   Client Failure Indication (CFI) is
   participating MEPs.

4.6. Pseudowire OAM

4.6.1. Pseudowire OAM using Virtual Circuit Connectivity Verification
   (VCCV)

   VCCV, as defined in [MPLS-TP-OAM] [VCCV], provides a means for end-to-end fault
   detection and diagnostics tools to allow
   the propagation information from one edge be extended for PWs (regardless of
   the network to the
   other. underlying tunneling technology). The information concerns a defect to VCCV switching function
   provides a client, control channel associated with each PW. [VCCV] defines
   three Control Channel (CC) types, i.e., three possible methods for
   transmitting and identifying OAM messages:

   o CC Type 1: In-band VCCV, as described in the case
   that the client does not support alarm notification.

3.4.3.8. Packet Loss Measurement (LM)

   Packet Loss Measurement [VCCV], is a function used also referred
      to verify the quality of as "PWE3 Control Word with 0001b as first nibble".  It uses the service. This function indicates
      PW Associated Channel Header [PW-ACH].

   o CC Type 2: Out-of-band VCCV [VCCV], is also referred to as "MPLS
      Router Alert Label". In this case the ratio of packets that are
   not delivered out of all packets that are transmitted control channel is created
      by using the path
   source.

   There are two possible ways of determining this measurement: MPLS router alert label [RFC3032] immediately above
      the PW label.

   o Using OAM packets, it CC Type 3: TTL expiry VCCV [VCCV], is possible also referred to compute the statistics based
      on a series of OAM packets. This, however, has as "MPLS PW
      Label with TTL == 1", i.e., the disadvantage of
      being artificial, and may not be representative since part control channel is identified when
      the value of the
      packet loss may be dependent upon packet sizes.

   o Sending delimiting messages for TTL field in the start and end of a measurement
      period during which PW label is set to 1.

   VCCV currently supports the source following OAM mechanisms: ICMP Ping, LSP
   Ping, and sink BFD. ICMP and LSP Ping are IP encapsulated before being
   sent over the PW ACH. BFD for VCCV [BFD-VCCV] supports two modes of
   encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
   PW-ACH encapsulated (with no IP/UDP header) and provides support to
   signal the path count AC status. The use of the
      packets transmitted and received. After VCCV control channel provides
   the end delimiter, context, based on the
      ratio would be calculated by MPLS-PW label, required to bind and
   bootstrap the path OAM entity.

3.4.3.9. Packet Delay Measurement (DM)

   Packet Delay Measurement is BFD session to a function that is used particular pseudo wire (FEC),
   eliminating the need to measure one-
   way or two-way delay exchange Discriminator values.

   VCCV consists of a packet transmission between a pair two components: (1) signaled component to
   communicate VCCV capabilities as part of VC label, and (2) switching
   component to cause the
   end-points of PW payload to be treated as a path (PW, LSP, or Section). Where:

   o One-way packet delay control packet.

   VCCV is not directly dependent upon the time elapsed from the start presence of
      transmission a control plane.
   The VCCV capability negotiation may be performed as part of the first bit PW
   signaling when LDP is used. In case of manual configuration of the packet
   PW, it is the responsibility of the operator to set consistent
   options at both ends. The manual option was created specifically to
   handle MPLS-TP use cases where no control plane was a requirement.
   However, new use cases such as pure mobile backhaul find this
   functionality useful too.

4.6.2. Pseudowire OAM using G-ACh

   As mentioned above, VCCV enables OAM for PWs by using a source node until control
   channel for OAM packets. When PWs are used in MPLS-TP networks,
   rather than the reception control channels defined in VCCV, the G-ACh can be
   used as an alternative control channel. The usage of the G-ACh for
   PWs is defined in [PW-G-ACh].

4.6.3. Attachment Circuit - Pseudowire Mapping

   The PWE3 working group has defined a mapping and notification of
   defect states between a pseudowire (PW) and the Attachment Circuits
   (ACs) of the end-to-end emulated service. This mapping is of key
   importance to the end-to-end functionality. Specifically, the mapping
   is provided by [PW-MAP], by [L2TP-EC] for L2TPv3 pseudowires, and
   Section 5.3 of [ATM-L2] for ATM.

4.7. OWAMP and TWAMP

4.7.1. Overview

   The IPPM working group in the IETF defines common criteria and
   metrics for measuring performance of IP traffic ([IPPM-FW]). Some of
   the key RFCs published by this working group have defined metrics for
   measuring connectivity [IPPM-Con], delay ([IPPM-1DM], [IPPM-2DM]),
   and packet loss [IPPM-1LM]. It should be noted that the work of the
   IETF in the context of performance metrics is not limited to IP
   networks; [PM-CONS] presents general guidelines for considering new
   performance metrics.

   The IPPM working group has defined not only metrics for performance
   measurement, but also protocols that define how the measurement is
   carried out. The One-way Active Measurement Protocol [OWAMP] and the
   Two-Way Active Measurement Protocol [TWAMP] define a method and
   protocol for measuring performance metrics in IP networks.

   OWAMP [OWAMP] enables measurement of one-way characteristics of IP
   networks, such as one-way packet loss and one-way delay.  For its
   proper operation OWAMP requires accurate time of day setting at its
   end points.

   TWAMP [TWAMP] is a similar protocol that enables measurement of both
   one-way and two-way (round trip) characteristics.

   OWAMP and TWAMP are both comprised of two separate protocols:

   o OWAMP-Control/TWAMP-Control: used to initiate, start, and stop
      test sessions and to fetch their results. Continuity Check and
      Connectivity Verification are tested and confirmed by establishing
      the OWAMP/TWAMP Control Protocol TCP connection.

   o OWAMP-Test/TWAMP-Test: used to exchange test packets between two
      measurement nodes. Enables the loss and delay measurement
      functions, as well as detection of other anomalies, such as packet
      duplication and packet reordering.

   It should be noted that while [OWAMP] and [TWAMP] define tools for
   performance measurement, they do not define the accuracy of these
   tools. The accuracy depends on scale, implementation and network
   configurations.

   Alternative protocols for performance monitoring are defined, for
   example, in MPLS-TP OAM ([MPLS-LM-DM], [TP-LM-DM]), and in Ethernet
   OAM [ITU-T-Y1731].

4.7.2. Control and Test Protocols

   OWAMP and TWAMP control protocols run over TCP, while the test
   protocols run over UDP.  The purpose of the control protocols is to
   initiate, start, and stop test sessions, and for OWAMP to fetch
   results.  The test protocols introduce test packets (which contain
   sequence numbers and timestamps) along the IP path under test
   according to a schedule, and record statistics of packet arrival.
   Multiple sessions may be simultaneously defined, each with a session
   identifier, and defining the number of packets to be sent, the amount
   of padding to be added (and thus the packet size), the start time,
   and the send schedule (which can be either a constant time between
   test packets or exponentially distributed pseudo-random). Statistics
   recorded conform to the relevant IPPM RFCs.

   OWAMP and TWAMP test traffic is designed with security in mind. Test
   packets are hard to detect because they are simply UDP streams
   between negotiated port numbers, with potentially nothing static in
   the packets.  OWAMP and TWAMP also include optional authentication
   and encryption for both control and test packets.

4.7.3. OWAMP

   OWAMP defines the following logical roles: Session-Sender, Session-
   Receiver, Server, Control-Client, and Fetch-Client.  The Session-
   Sender originates test traffic that is received by the Session-
   Receiver.  The Server configures and manages the session, as well as
   returning the results.  The Control-Client initiates requests for
   test sessions, triggers their start, and may trigger their
   termination.  The Fetch-Client requests the results of a completed
   session.  Multiple roles may be combined in a single host - for
   example, one host may play the roles of Control-Client, Fetch-Client,
   and Session-Sender, and a second playing the roles of Server and
   Session-Receiver.

   In a typical OWAMP session the Control-Client establishes a TCP
   connection to port 861 of the Server, which responds with a server
   greeting message indicating supported security/integrity modes. The
   Control-Client responds with the chosen communications mode and the
   Server accepts the modes.  The Control-Client then requests and fully
   describes a test session to which the Server responds with its
   acceptance and supporting information.  More than one test session
   may be requested with additional messages.  The Control-Client then
   starts a test session and the Server acknowledges.  The Session-
   Sender then sends test packets with pseudorandom padding to the
   Session-Receiver until the session is complete or until the Control-
   client stops the session.  Once finished, the Fetch-Client sends a
   fetch request to the server, which responds with an acknowledgement
   and immediately thereafter the result data.

4.7.4. TWAMP

   TWAMP defines the following logical roles: session-sender, session-
   reflector, server, and control-client.  These are similar to the
   OWAMP roles, except that the Session-Reflector does not collect any
   packet information, and there is no need for a Fetch-Client.

   In a typical TWAMP session the Control-Client establishes a TCP
   connection to port 862 of the Server, and mode is negotiated as in
   OWAMP.  The Control-Client then requests sessions and starts them.
   The Session-Sender sends test packets with pseudorandom padding to
   the Session-Reflector which returns them with insertion of
   timestamps.

4.8. TRILL

   The requirements of OAM in TRILL are defined in [TRILL-OAM]. The main
   challenge in TRILL OAM is that traffic between RBridges RB1 and RB2
   may be forwarded through more than one path. Thus, an OAM protocol
   between RBridges RB1 and RB2 must be able to monitor all the
   available paths between the two RBridge.

   During the writing of this document the detailed definition of the
   TRILL OAM tools are still work in progress. This subsection presents
   the main requirements of TRILL OAM.

   The main requirements defined in [TRILL-OAM] are:

   o Continuity Checking (CC) - the TRILL OAM protocol must support a
      function for CC between any two RBridges RB1 and RB2.

   o Connectivity Verification (CV) - connectivity between two RBridges
      RB1 and RB2 can be verified on a per-flow basis.

   o Path Tracing - allows an RBridge to trace all the available paths
      to a peer RBridge.

   o Performance monitoring - allows an RBridge to monitor the packet
      loss and packet delay to a peer RBridge.

4.9. Summary of OAM Mechanisms

   This subsection provides a short summary of each of the OAM mechanism
   categories described in this document.

   A detailed list of the RFCs related to each category is given in
   Appendix A.1.

   +-----------+------------------------------------------+------------+
   | Category  | Description                              | Transport  |
   |           |                                          | Technology |
   +-----------+------------------------------------------+------------+
   |IP Ping    | Ping ([IntHost], [NetTerms]) is a simple | IPv4/IPv6  |
   |           | application for testing reachability that|            |
   |           | uses ICMP Echo messages ([ICMPv4],       |            |
   |           | [ICMPv6]).                               |            |
   +-----------+------------------------------------------+------------+
   |IP         | Traceroute ([TCPIP-Tools], [NetTools]) is| IPv4/IPv6  |
   |Traceroute | an application that allows users to trace|            |
   |           | the path between an IP source and an IP  |            |
   |           | destination, i.e., to identify the nodes |            |
   |           | along the path. If more than one path    |            |
   |           | exists between the source and destination|            |
   |           | Traceroute traces *a* path. The most     |            |
   |           | common implementation of Traceroute      |            |
   |           | uses UDP probe messages, although there  |            |
   |           | are other implementations that use       |            |
   |           | different probes, such as ICMP or TCP.   |            |
   +-----------+------------------------------------------+------------+
   |BFD        | Bidirectional Forwarding Detection (BFD) | generic    |
   |           | is defined in [BFD] as a framework for a |            |
   |           | lightweight generic OAM mechanism.  The  |            |
   |           | intention is to define a base mechanism  |            |
   |           | that can be used with various            |            |
   |           | encapsulation types, network             |            |
   |           | environments, and in various medium      |            |
   |           | types.                                   |            |
   +-----------+------------------------------------------+------------+
   |MPLS OAM   | MPLS LSP Ping, as defined in [MPLS-OAM], | MPLS       |
   |           | [MPLS-OAM-FW] and [LSP-Ping], is an OAM  |            |
   |           | mechanism for point-to-point and         |            |
   |           | point-to-multipoint MLPS LSPs.           |            |
   |           | It includes two main functions: Ping and |            |
   |           | Traceroute.                              |            |
   |           | It is noted that while this category     |            |
   |           | focuses on LSP Ping, other OAM mechanisms|            |
   |           | can be used in MPLS networks, e.g., BFD. |            |
   +-----------+------------------------------------------+------------+
   |MPLS-TP OAM| MPLS-TP OAM is defined in a set of RFCs. | MPLS-TP    |
   |           | The OAM requirements for MPLS Transport  |            |
   |           | Profile (MPLS-TP) are defined in         |            |
   |           | [MPLS-TP-OAM]. Each of the tools in the  |            |
   |           | OAM toolset is defined in its own RFC, as|            |
   |           | specified in Section A.1.                |            |
   +-----------+------------------------------------------+------------+
   |Pseudowire | The PWE3 OAM architecture defines control| Pseudowire |
   |OAM        | channels that support the use of existing|            |
   |           | IETF OAM tools to be used for a pseudo-  |            |
   |           | wire (PW).  The control channels that are|            |
   |           | defined in [VCCV] and [PW-G-ACh] may be  |            |
   |           | used in conjunction with ICMP Ping, LSP  |            |
   |           | Ping, and BFD to perform CC and CV       |            |
   |           | functionality.  In addition the channels |            |
   |           | support use of any of the MPLS-TP based  |            |
   |           | OAM tools for completing their respective|            |
   |           | OAM functionality for a PW.              |            |
   +-----------+------------------------------------------+------------+
   |OWAMP and  | The One Way Active Measurement Protocol  | IPv4/IPv6  |
   |TWAMP      | (OWAMP) and the Two Way Active Measure-  |            |
   |           | ment Protocols (TWAMP) are two protocols |            |
   |           | defined in the IP Performance Metrics    |            |
   |           | (IPPM) working group in the IETF. These  |            |
   |           | protocols allow various performance      |            |
   |           | metrics to be measured, such as packet   |            |
   |           | loss, delay and delay variation,         |            |
   |           | duplication and reordering.              |            |
   +-----------+------------------------------------------+------------+
   |TRILL OAM  | The requirements of OAM in TRILL are     | TRILL      |
   |           | defined in [TRILL-OAM]. These            |            |
   |           | requirements include continuity checking,|            |
   |           | connectivity verification, path tracing  |            |
   |           | and performance monitoring. During the   |            |
   |           | writing of this document the detailed    |            |
   |           | definition of the TRILL OAM tools        |            |
   |           | is work in progress.                     |            |
   +-----------+------------------------------------------+------------+
              Table 3 Summary of OAM-related IETF Mechanisms

4.10. Summary of OAM Functions

   Table 4 summarizes the OAM functions that are supported in each of
   the categories that were analyzed in this section. The columns of
   this tables are the typical OAM functions described in Section 1.3.

       +-----------+-------+--------+--------+-------+----------+
       |           |Continu|Connecti|Path    |Perform|Other     |
       |           |ity    |vity    |Discover|ance   |Function  |
       |           |Check  |Verifica|y       |Monitor|s         |
       | Category  |       |tion    |        |ing    |          |
       +-----------+-------+--------+--------+-------+----------+
       |IP Ping    |Echo   |        |        |       |          |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |IP         |       |        |Tracerou|       |          |
       |Traceroute |       |        |te      |       |          |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |BFD        |BFD    |BFD     |        |       |RDI usi-  |
       |           |Control|Control |        |       |ng BFD    |
       |           |/ Echo |        |        |       |Control   |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |MPLS OAM   |       |"Ping"  |"Tracero|       |          |
       |(LSP Ping) |       |mode    |ute"    |       |          |
       |           |       |        |mode    |       |          |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |MPLS-TP    |CC     |CV/pro- |Route   |-LM    |-Diagnos- |
       |OAM        |       |active  |Tracing |-DM    | tic Test |
       |           |       |or on-  |        |       |-Lock     |
       |           |       |demand  |        |       |-Alarm    |
       |           |       |        |        |       |Reporting |
       |           |       |        |        |       |-Client   |
       |           |       |        |        |       |Failure   |
       |           |       |        |        |       |Indication|
       |           |       |        |        |       |-RDI      |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |Pseudowire |BFD    |-BFD    |LSP-Ping|       |          |
       |OAM        |       |-ICMP   |        |       |          |
       |           |       | Ping   |        |       |          |
       |           |       |-LSP-   |        |       |          |
       |           |       | Ping   |        |       |          |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |OWAMP and  | - control      |        |-Delay |          |
       |TWAMP      |   protocol     |        | measur|          |
       |           |                |        | ement |          |
       |           |                |        |-Packet|          |
       |           |                |        | loss  |          |
       |           |                |        | measur|          |
       |           |                |        | ement |          |
       + --------- + ----- + ------ + ------ + ----- + -------- +
       |TRILL OAM  |CC     |CV      |Path    |-Delay |          |
       |           |       |        |tracing | measur|          |
       |           |       |        |        | ement |          |
       |           |       |        |        |-Packet|          |
       |           |       |        |        | loss  |          |
       |           |       |        |        | measur|          |
       |           |       |        |        | ement |          |
       +-----------+-------+--------+--------+-------+----------+
      Table 4 Summary of the last bit OAM Functionality in IETF OAM Mechanisms

5. Security Considerations

   This memo presents an overview of that packet by existing OAM mechanisms, and
   proposes no new OAM mechanisms. Therefore, this document introduces
   no security considerations. However, the destination
      node.

   o Two-way packet delay OAM mechanism reviewed in
   this document can and do present security issues. The reader is
   encouraged to review the time elapsed from the start of
      transmission of the first bit Security Considerations section of the packet each
   document referenced by a source node until
      the reception of the last bit of the loop-backed packet this memo.

6. IANA Considerations

   There are no new IANA considerations implied by the
      same source node, when the loopback is performed at the packet's
      destination node.

   Similarly to the packet loss measurement this could be performed in
   either document.

7. Acknowledgments

   The authors gratefully acknowledge Sasha Vainshtein, Carlos
   Pignataro, David Harrington, Dan Romascanu, Ron Bonica and other
   members of the OPSAWG mailing list for their helpful comments.

   This document was prepared using 2-Word-v2.0.template.dot.

8. References

8.1. Informative References

   [LSP-Ping]    Kompella, K., Swallow, G., "Detecting Multi-Protocol
                 Label Switched (MPLS) Data Plane Failures", RFC 4379,
                 February 2006.

   [MPLS-OAM]    Nadeau, T., Morrow, M., Swallow, G., Allan, D.,
                 Matsushima, S., "Operations and Management (OAM)
                 Requirements for Multi-Protocol Label Switched (MPLS)
                 Networks", RFC 4377, February 2006.

   [MPLS-OAM-FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol
                 Label Switching (MPLS) Operations and Management
                 (OAM)", RFC 4378, February 2006.

   [OAM-Label]   Ohta, H., "Assignment of the two ways outlined above.

3.5. PWE3 OAM

3.5.1. PWE3 'OAM Alert Label' for
                 Multiprotocol Label Switching Architecture (MPLS)
                 Operation and Maintenance (OAM) Functions", RFC 3429,
                 November 2002.

   [MPLS-TP-OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for
                 OAM using in MPLS Transport Networks", RFC 5860, May 2010.

   [G-ACh]       Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic
                 Associated Channel", RFC 5586, June 2009.

   [VCCV]        Nadeau, T., Pignataro, C., "Pseudowire Virtual Circuit
                 Connectivity Verification (VCCV)

   VCCV, as defined in [VCCV], provides a means (VCCV): A Control Channel
                 for end-to-end fault
   detection and diagnostics tools to be extended Pseudowires", RFC 5085, December 2007.

   [PW-ACH]      Bryant, S., Swallow, G., Martini, L., McPherson, D.,
                 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word
                 for PWs (regardless of
   the underlying tunneling technology). The VCCV switching function
   provides a control channel associated with each PW (based on the PW
   Associated Channel Header (ACH) which is defined in [PW-ACH]), and
   allows transmitting the OAM packets in-band with PW data (using CC
   Type 1: In-band VCCV).

   VCCV currently supports the following OAM mechanisms: ICMP Ping, LSP
   Ping, and BFD. ICMP Use over an MPLS PSN", RFC 4385, February 2006.

   [ATM-L2]      Singh, S., Townsley, M., and LSP Ping are IP encapsulated before being
   sent C. Pignataro,
                 "Asynchronous Transfer Mode (ATM) over the PW ACH. BFD for VCCV [BFD-VCCV] supports two modes of
   encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
   PW-ACH encapsulated (with no IP/UDP header) Layer 2
                 Tunneling Protocol Version 3 (L2TPv3)", RFC 4454, May
                 2006.

   [L2TP-EC]     McGill, N. and C. Pignataro, "Layer 2 Tunneling
                 Protocol Version 3 (L2TPv3) Extended Circuit Status
                 Values", RFC 5641, August 2009.

   [PW-MAP]      Aissaoui, M., Busschbach, P., Martini, L., Morrow, M.,
                 Nadeau, T., and provides support to
   signal the AC status. The use of the VCCV control channel provides
   the context, based on the MPLS-PW label, required to bind Y(J). Stein, "Pseudowire (PW)
                 Operations, Administration, and
   bootstrap the BFD session to a particular pseudo wire (FEC),
   eliminating the need to exchange Discriminator values.

   VCCV consists of two components: (1) signaled component to
   communicate VCCV capabilities as part of VC label, Maintenance (OAM)
                 Message Mapping", RFC 6310, July 2011.

   [ICMPv4]      Postel, J., "Internet Control Message Protocol", STD 5,
                 RFC 792, September 1981.

   [ICMPv6]      Conta, A., Deering, S., and (2) switching
   component to cause the PW payload to be treated as a control packet.

   VCCV is not directly dependent upon the presence of a control plane.
   The VCCV capability negotiation may be performed as part of the PW
   signaling when LDP is used. In case of manual configuration of the
   PW, it is M. Gupta, "Internet Control
                 Message Protocol (ICMPv6) for the responsibility Internet Protocol
                 Version 6 (IPv6) Specification", RFC 4443, March 2006.

   [IntHost]     Braden, R., "Requirements for Internet Hosts --
                 Communication Layers", RFC 1122, October 1989.

   [NetTerms]    Jacobsen, O., Lynch, D., "A Glossary of the operator to set consistent
   options at both ends.

3.5.2. PWE3 OAM using G-ACh

   As mentioned above, VCCV enables OAM Networking
                 Terms", RFC 1208, March 1991.

   [MPLS-P2MP]   Yasukawa, S., Farrel, A., King, D., Nadeau, T.,
                 "Operations and Management (OAM) Requirements for
                 Point-to-Multipoint MPLS Networks", RFC 4687,
                 September 2006.

   [ICMP-Ext]    Bonica, R., Gan, D., Tappan, D., Pignataro, C., "ICMP
                 Extensions for Multiprotocol Label Switching", RFC
                 4950, August 2007.

   [ICMP-MP]     Bonica, R., Gan, D., Tappan, D., Pignataro, C.,
                 "Extended ICMP to Support Multi-Part Messages", RFC
                 4884, April 2007.

   [ICMP-Int]    Atlas, A., Bonica, R., Pignataro, C., Shen, N., Rivers,
                 JR., "Extending ICMP for PWs by using Interface and Next-Hop
                 Identification", RFC 5837, April 2010.

   [TCPIP-Tools] Kessler, G., Shepard, S., "A Primer On Internet and
                 TCP/IP Tools and Utilities", RFC 2151, June 1997.

   [NetTools]    Enger, R., Reynolds, J., "FYI on a control
   channel for OAM packets. When PWs are used in MPLS-TP networks,
   rather than the control channels defined in VCCV, the G-ACh can be
   used as an alternative control channel. The usage of the G-ACh Network Management
                 Tool Catalog: Tools for
   PWs is defined in [PW-G-ACh].

3.6. OWAMP Monitoring and TWAMP

3.6.1. Overview

   The IPPM working group in the IETF defines common criteria Debugging
                 TCP/IP Internets and
   metrics Interconnected Devices", RFC
                 1470, June 1993.

   [IPPM-FW]     Paxson, V., Almes, G., Mahdavi, J., and Mathis, M.,
                 "Framework for measuring performance of IP traffic ([IPPM-FW]). Some of
   the key RFCs published by this working group have defined metrics Performance Metrics", RFC 2330, May
                 1998.

   [IPPM-Con]    Mahdavi, J., Paxson, V., "IPPM Metrics for
   measuring connectivity [IPPM-Con], delay ([IPPM-1DM], [IPPM-2DM]),
   and packet loss [IPPM-1LM].

   Alternative protocols Measuring
                 Connectivity", RFC 2678, September 1999.

   [IPPM-1DM]    Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
                 Delay Metric for performance measurement are defined, IPPM", RFC 2679, September 1999.

   [IPPM-1LM]    Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
                 Packet Loss Metric for
   example, in MPLS-TP OAM ([MPLS-LM-DM], [TP-LM-DM]), and in Ethernet
   OAM [ITU-T-Y1731].

   The IPPM working group has defined not only metrics IPPM", RFC 2680, September
                 1999.

   [IPPM-2DM]    Almes, G., Kalidindi, S., Zekauskas, M., "A Round-trip
                 Delay Metric for IPPM", RFC 2681, September 1999.

   [PM-CONS]     Clark, A. and B. Claise, "Guidelines for performance
   measurement, but also protocols that define how the measurement is
   carried out. The Considering
                 New Performance Metric Development", BCP 170, RFC
                 6390, October 2011.

   [OWAMP]       Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and
                 Zekauskas, M., "A One-way Active Measurement Protocol [OWAMP]
                 (OWAMP)", RFC 4656, September 2006.

   [TWAMP]       Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and the
                 Babiarz, J., "A Two-Way Active Measurement Protocol [TWAMP] define a method
                 (TWAMP)", RFC 5357, October 2008.

   [Reorder]     Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
                 S., and
   protocol J. Perser, "Packet Reordering Metrics", RFC
                 4737, November 2006.

   [Dup]         Uijterwaal, H., "A One-Way Packet Duplication Metric",
                 RFC 5560, May 2009.

   [BFD]         Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD)", RFC 5880, June 2010.

   [BFD-IP]      Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD) for measuring delay and packet loss in IP networks.

   OWAMP [OWAMP] enables measurement of one-way characteristics of IP
   networks, such as one-way packet loss and one-way delay.  For its
   proper operation OWAMP requires accurate time of day setting at its
   end points.

   TWAMP [TWAMP] is a similar protocol that enables measurement of two-
   way (round trip) characteristics.  TWAMP does not require accurate
   time of day, and, furthermore, allows the use of a simple session
   reflector, making it an attractive alternative to OWAMP.

   OWAMP and TWAMP use two separate protocols: a Control plane protocol,
   and a Test plane protocol.

3.6.2. Control and Test Protocols

   OWAMP IPv4 and TWAMP control protocols run over TCP, while the test
   protocols run over UDP.  The purpose IPv6 (Single Hop)", RFC 5881, June
                 2010.

   [BFD-Gen]     Katz, D., Ward, D., "Generic Application of
                 Bidirectional Forwarding Detection (BFD)", RFC 5882,
                 June 2010.

   [BFD-Multi]   Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD) for Multihop Paths", RFC 5883, June 2010.

   [BFD-LSP]     Aggarwal, R., Kompella, K., Nadeau, T., and Swallow,
                 G., "Bidirectional Forwarding Detection (BFD) for MPLS
                 Label Switched Paths (LSPs)", RFC 5884, June 2010.

   [BFD-VCCV]    Nadeau, T., Pignataro, C., "Bidirectional Forwarding
                 Detection (BFD) for the control protocols is to
   initiate, start, Pseudowire Virtual Circuit
                 Connectivity Verification (VCCV)", RFC 5885, June
                 2010.

   [TP-OAM-FW]   Busi, I., Allan, D., "Operations, Administration and stop test sessions,
                 Maintenance Framework for MPLS-based Transport
                 Networks ", RFC 6371, September 2011.

   [TP-CC-CV]    Allan, D., Swallow, G., Drake, J., "Proactive
                 Connectivity Verification, Continuity Check and Remote
                 Defect indication for OWAMP to fetch
   results.  The test protocols introduce test packets (which contain
   sequence numbers MPLS Transport Profile", RFC
                 6428, November 2011.

   [OnDemand-CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS
                 On-Demand Connectivity Verification and timestamps) along the IP path under test
   according to a schedule, Route
                 Tracing", RFC 6426, November 2011.

   [MPLS-LM-DM]  Frost, D., Bryant, S., "Packet Loss and record statistics of packet arrival.
   Multiple sessions may be simultaneously defined, each with a session
   identifier, Delay
                 Measurement for MPLS Networks", RFC 6374, September
                 2011.

   [TP-LM-DM]    Frost, D., Bryant, S., "A Packet Loss and defining the number of packets to be sent, the amount
   of padding to be added (and thus the packet size), the start time, Delay
                 Measurement Profile for MPLS-Based Transport
                 Networks", RFC 6375, September 2011.

   [TP-Fault]    Swallow, G., Fulignoli, A., Vigoureux, M., Boutros, S.,
                 "MPLS Fault Management Operations, Administration, and the send schedule (which can be either
                 Maintenance (OAM)", RFC 6427, November 2011.

   [Lock-Loop]   Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux,
                 M., Dai, X., "MPLS Transport Profile Lock Instruct and
                 Loopback Functions", RFC 6435, November 2011.

   [ITU-T-CT]    Betts, M., "Allocation of a constant time between
   test packets or exponentially distributed pseudo-random). Statistics
   recorded conform to the relevant IPPM RFCs.

   OWAMP Generic Associated Channel
                 Type for ITU-T MPLS Transport Profile Operation,
                 Maintenance, and TWAMP test traffic is designed with security in mind.  Test
   packets are hard to detect because they are simply UDP streams
   between negotiated port numbers, with potentially nothing static Administration (MPLS-TP OAM)", RFC
                 6671, November 2012.

   [PW-Map]      M. Aissaoui, P. Busschbach, L. Martini, M. Morrow, T.
                 Nadeau, "Pseudowire (PW) Operations, Administration,
                 and Maintenance (OAM) Message Mapping", RFC 6310, July
                 2011.

   [PW-G-ACh]    Li, H., Martini, L., He, J., Huang, F., "Using the
                 Generic Associated Channel Label for Pseudowire in the packets.  OWAMP and TWAMP also include optional authentication
   and encryption
                 MPLS Transport Profile (MPLS-TP)", RFC 6423, November
                 2011.

   [OAM-Def]     Andersson, L., Van Helvoort, H., Bonica, R., Romascanu,
                 D., Mansfield, S., "Guidelines for both control and test packets.

3.6.3. OWAMP

   OWAMP defines the following logical roles: Session-Sender, Session-
   Receiver, Server, Control-Client, and Fetch-Client.  The Session-
   Sender originates test traffic that is received by use of the Session-
   Receiver.  The Server configures and manages OAM
                 acronym in the session, as well as
   returning IETF ", RFC 6291, June 2011.

   [OAM-Analys]  Sprecher, N., Fang, L., "An Overview of the results.  The Control-Client initiates requests OAM Tool
                 Set for
   test sessions, triggers their start, and may trigger their
   termination.  The Fetch-Client requests  MPLS based Transport Networks", RFC 6669,
                 July 2012.

   [TP-Term]     Van Helvoort, H., Andersson, L., Sprecher, N., "A
                 Thesaurus for the Terminology used in Multiprotocol
                 Label Switching Transport Profile (MPLS-TP)
                 drafts/RFCs and ITU-T's Transport Network
                 Recommendations", work-in-progress, draft-ietf-mpls-
                 tp-rosetta-stone, July 2012.

   [Cont]        Dugal, D., Pignataro, C., Dunn, R., "Protecting the results
                 Router Control Plane", RFC 6192, March 2011.

   [Mng]         Farrel, A., "Inclusion of a completed
   session.  Multiple roles may be combined Manageability Sections in a single host -
                 Path Computation Element (PCE) Working Group Drafts",
                 RFC 6123, February 2011.

   [TRILL-OAM]   Senevirathne, T., Bond, D., Aldrin, S., Li, Y., Watve,
                 R., "Requirements for
   example, one host may play the roles Operations, Administration, and
                 Maintenance (OAM) in Transparent Interconnection of Control-Client, Fetch-Client,
                 Lots of Links (TRILL)", RFC 6905, March 2013.

   [IEEE802.1Q]  IEEE 802.1Q, "IEEE Standard for Local and Session-Sender, metropolitan
                 area networks - Media Access Control (MAC) Bridges and a second playing the roles of Server
                 Virtual Bridged Local Area Networks", October 2012.

   [ITU-T-Y1731] ITU-T Recommendation G.8013/Y.1731, "OAM Functions and
   Session-Receiver.

   In a typical OWAMP session the Control-Client establishes a TCP
   connection to port 861 of the Server, which responds with a server
   greeting message indicating supported security/integrity modes. The
   Control-Client responds
                 Mechanisms for Ethernet-based Networks", July 2011.

   [ITU-T-Y1711] ITU-T Recommendation Y.1711, "Operation & Maintenance
                 mechanism for MPLS networks", February 2004.

   [IEEE802.3ah] IEEE 802.3, "IEEE Standard for Information technology -
                 Local and metropolitan area networks - Carrier sense
                 multiple access with the chosen communications mode collision detection (CSMA/CD)
                 access method and the
   Server accepts the modes.  The Control-Client then requests physical layer specifications",
                 clause 57, December 2008.

   [ITU-T-G.806] ITU-T Recommendation G.806, "Characteristics of
                 transport equipment - Description methodology and fully
   describes a test session to which the Server responds with its
   acceptance
                 generic functionality", January 2009.

   [ITU-G8113.2] ITU-T Recommendation G.8113.2/Y.1372.2, "Operations,
                 administration and supporting information.  More than one test session
   may be requested with additional messages.  The Control-Client then
   starts a test session maintenance mechanisms for MPLS-TP
                 networks using the tools defined for MPLS", November
                 2012.

   [ITU-G8113.1] ITU-T Recommendation G.8113.1/Y.1372.1, "Operations,
                 Administration and Maintenance mechanism for MPLS-TP
                 in Packet Transport Network (PTN)", November 2012.

Appendix A.                 List of OAM Documents

A.1. List of IETF OAM Documents

   Table 5 summarizes the Server acknowledges.  The Session-
   Sender then sends test packets with pseudorandom padding to the
   Session-Receiver until OAM related RFCs published by the session IETF.

   It is complete important to note that the table lists various RFCs that are
   different by nature. For example, some of these documents define OAM
   tools or until OAM protocols (or both), while others define protocols that
   are not strictly OAM-related, but are used by OAM tools. The table
   also includes memos that define the Control-
   client stops requirements or the session.  Once finished, framework of
   OAM in the Fetch-Client sends context of a
   fetch request specific transport technology, or describe
   how to use existing OAM tools in a new transport technology.

   The RFCs in the server, which responds with an acknowledgement
   and immediately thereafter the result data.

3.6.4. TWAMP

   TWAMP defines table are categorized in a few sets as defined in
   Section 1.3.

   +-----------+--------------------------------------+----------+
   | Category  | Title                                | RFC      |
   +-----------+--------------------------------------+----------+
   |IP Ping    | Requirements for Internet Hosts --   | RFC 1122 |
   |           | Communication Layers [IntHost]       |          |
   |           +--------------------------------------+----------+
   |           | A Glossary of Networking Terms       | RFC 1208 |
   |           | [NetTerms]                           |          |
   |           +--------------------------------------+----------+
   |           | Internet Control Message Protocol    | RFC 792  |
   |           | [ICMPv4]                             |          |
   |           +--------------------------------------+----------+
   |           | Internet Control Message Protocol    | RFC 4443 |
   |           | (ICMPv6) for the following logical roles: session-sender, session-
   reflector, server, Internet Protocol   |          |
   |           | Version 6 (IPv6) Specification       |          |
   |           | [ICMPv6]                             |          |
   +-----------+--------------------------------------+----------+
   |IP         | A Primer On Internet and TCP/IP      | RFC 2151 |
   |Traceroute | Tools and control-client.  These are similar to the
   OWAMP roles, except that the Session-Reflector does not collect any
   packet information, Utilities [TCPIP-Tools]    |          |
   |           +--------------------------------------+----------+
   |           | FYI on a Network Management Tool     | RFC 1470 |
   |           | Catalog: Tools for Monitoring and there is no need    |          |
   |           | Debugging TCP/IP Internets and       |          |
   |           | Interconnected Devices [NetTools]    |          |
   |           +--------------------------------------+----------+
   |           | Internet Control Message Protocol    | RFC 792  |
   |           | [ICMPv4]                             |          |
   |           +--------------------------------------+----------+
   |           | Internet Control Message Protocol    | RFC 4443 |
   |           | (ICMPv6) for a Fetch-Client.

   In a typical TWAMP session the Control-Client establishes a TCP
   connection Internet Protocol   |          |
   |           | Version 6 (IPv6) Specification       |          |
   |           | [ICMPv6]                             |          |
   |           +--------------------------------------+----------+
   |           | Extended ICMP to port 862 of the Server, Support Multi-Part  | RFC 4884 |
   |           | Messages [ICMP-MP]                   |          |
   |           +--------------------------------------+----------+
   |           | Extending ICMP for Interface and mode is negotiated as in
   OWAMP.  The Control-Client then requests sessions     | RFC 5837 |
   |           | Next-Hop Identification [ICMP-Int]   |          |
   +-----------+--------------------------------------+----------+
   |BFD        | Bidirectional Forwarding Detection   | RFC 5880 |
   |           | [BFD]                                |          |
   |           +--------------------------------------+----------+
   |           | Bidirectional Forwarding Detection   | RFC 5881 |
   |           | (BFD) for IPv4 and starts them.
   The Session-Sender sends test packets with pseudorandom padding to
   the Session-Reflector which returns them with insertion of
   timestamps.

3.7. Summary of OAM Functions

   Table 3 summarizes the OAM functions that are supported in each of
   the categories that were analyzed in this section.

   +-----------+-------+--------+--------+-----------+-------+--------+ IPv6 (Single Hop) |          |
   |           | [BFD-IP]                             |          | Standard  |Continu|Connecti|Path    |Defect     |Perform|Other
   |           +--------------------------------------+----------+
   |           |ity    |vity    |Discover|Indications|ance   |Function|           |           |Check  |Verifica|y Generic Application of Bidirectional |           |Monitor|s RFC 5882 |
   |           |       |tion Forwarding Detection [BFD-Gen]       |          |           |ing
   |           +--------------------------------------+----------+
   |
   +-----------+-------+--------+--------+-----------+-------+--------+
   |IP Ping           |       |Echo Bidirectional Forwarding Detection   | RFC 5883 |
   |           | (BFD) for Multihop Paths [BFD-Multi] |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |IP          |
   |        |Tracerou|           +--------------------------------------+----------+
   |           | Bidirectional Forwarding Detection   |
   |Traceroute RFC 5884 |
   |        |te           | for MPLS Label Switched Paths (LSPs) |          |
   |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |BFD        |BFD    |BFD           | [BFD-LSP]                            |          |
   |           +--------------------------------------+----------+
   |           |           |Control|Echo Bidirectional Forwarding Detection   | RFC 5885 |
   |           | for the Pseudowire Virtual Circuit   |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |MPLS OAM          |       |"Ping"  |"Tracero|
   |           | Connectivity Verification (VCCV)     |          |
   |(LSP Ping)
   |       |mode    |ute"           | [BFD-VCCV]                           |          |
   +-----------+--------------------------------------+----------+
   |MPLS OAM   | Operations and Management (OAM)      | RFC 4377 |
   |        |mode           | Requirements for Multi-Protocol Label|          |
   |           |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |MPLS-TP    |CC     |CV/pro- |Route   |-Alarm     |-LM    |-Diagnos|
   |OAM Switched (MPLS) Networks [MPLS-OAM]  |       |active  |Tracing          | Reporting |-DM
   | tic Tes|           +--------------------------------------+----------+
   |           |       |or on- A Framework for Multi-Protocol       |        |-Client RFC 4378 |
   |           | Label Switching (MPLS) Operations    |          | t
   |           | and Management (OAM) [MPLS-OAM-FW]   |       |demand          |
   | Failure           +--------------------------------------+----------+
   |       |-Lock           | Detecting Multi-Protocol Label       | RFC 4379 |
   |           | Switched (MPLS) Data Plane Failures  |          | Indication|
   |           | [LSP-Ping]                           |          |
   |           +--------------------------------------+----------+
   |        |-Remote           | Operations and Management (OAM)      | RFC 4687 |
   |           | Requirements for Point-to-Multipoint |          |
   | Defect           | MPLS Networks [MPLS-P2MP]            |          |
   |           +--------------------------------------+----------+
   |           | ICMP Extensions for Multiprotocol    | RFC 4950 | Indication|
   |           |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |PWE3 OAM   |BFD    |-BFD    |LSP-Ping| Label Switching [ICMP-Ext]           |          |
   +-----------+--------------------------------------+----------+
   |MPLS-TP    | Requirements for OAM in MPLS-TP      | RFC 5860 |       |-ICMP
   |OAM        | [MPLS-TP-OAM]                        |          |
   |           +--------------------------------------+----------+
   |           | MPLS Generic Associated Channel      | RFC 5586 | Ping
   |           | [G-ACh]                              |          |
   |           +--------------------------------------+----------+
   |           |       |-LSP- MPLS-TP OAM Framework                | RFC 6371 |
   |           | [TP-OAM-FW]                          |          |
   |           +--------------------------------------+----------+
   | Ping           | Proactive Connectivity Verification, | RFC 6428 |
   |           |
   + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
   |OWAMP Continuity Check, and Remote Defect  |          |
   |           |           |-Delay |        |
   |TWAMP Indication for the MPLS Transport    |          |
   |           | Profile [TP-CC-CV]                   | measur|          |
   |           +--------------------------------------+----------+
   |           | MPLS On-Demand Connectivity          | RFC 6426 |
   | ement           | Verification and Route Tracing       |          |
   |           | [OnDemand-CV]                        |          |           |-Packet|
   |           +--------------------------------------+----------+
   |           | MPLS Fault Management Operations,    | RFC 6427 |
   |           | loss Administration, and Maintenance (OAM)|          |
   |           | [TP-Fault]                           |          |
   |           +--------------------------------------+----------+
   |           | measur| MPLS Transport Profile Lock Instruct | RFC 6435 |
   |           | and Loopback Functions [Lock-Loop]   |          |
   | ement           +--------------------------------------+----------+
   |           |
   +-----------+-------+--------+--------+-----------+-------+--------+
                     Table 3 Summary of OAM Functions

4. Security Considerations

   This memo presents an overview of existing OAM mechanisms, and
   proposes no new OAM mechanisms. Therefore, this document introduces
   no security considerations. However, the OAM mechanism reviewed in
   this document can and do present security issues. The reader is
   encouraged to review the Security Considerations section of each
   document reference by this memo.

5. IANA Considerations

   There are no new IANA considerations implied by this document.

6. Acknowledgments

   The authors gratefully acknowledge Sasha Vainshtein, Carlos
   Pignataro, David Harrington, Dan Romascanu, Ron Bonica and other
   members of the OPSAWG mailing list for their helpful comments.

   This document was prepared using 2-Word-v2.0.template.dot.

7. References

7.1. Normative References

   [LSP-Ping]    Kompella, K., Swallow, G., "Detecting Multi-Protocol
                 Label Switched (MPLS) Data Plane Failures", RFC 4379,
                 February 2006.

   [MPLS-OAM]    Nadeau, T., Morrow, M., Swallow, G., Allan, D.,
                 Matsushima, S., "Operations and Management (OAM)
                 Requirements for Multi-Protocol Label Switched (MPLS)
                 Networks", RFC 4377, February 2006.

   [MPLS-OAM-FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol
                 Label Switching (MPLS) Operations Packet Loss and Management
                 (OAM)", Delay Measurement for| RFC 4378, February 2006.

   [OAM-Label]   Ohta, H., "Assignment of the 'OAM Alert Label' for
                 Multiprotocol Label Switching Architecture (MPLS)
                 Operation 6374 |
   |           | MPLS Networks [MPLS-LM-DM]           |          |
   |           +--------------------------------------+----------+
   |           | A Packet Loss and Maintenance (OAM) Functions", Delay Measurement  | RFC 3429,
                 November 2002.

   [MPLS-TP-OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements 6375 |
   |           | Profile for
                 OAM in MPLS MPLS-Based Transport Networks", RFC 5860, May 2010.

   [G-ACh]       Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic
                 Associated Channel", RFC 5586, June 2009.

   [VCCV]        Nadeau, T., Pignataro, C., "Pseudowire     |          |
   |           | Networks [TP-LM-DM]                  |          |
   +-----------+--------------------------------------+----------+
   |Pseudowire | Pseudowire Virtual Circuit           | RFC 5085 |
   |OAM        | Connectivity Verification (VCCV):    |          |
   |           | A Control Channel for Pseudowires", RFC 5085, December 2007.

   [PW-ACH]      Bryant, S., Swallow, G., Martini, L., McPherson, D.,
                 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word
                 for Use over an MPLS PSN", RFC 4385, February 2006.

   [ICMPv4]      Postel, J., "Internet Control Message Protocol", STD 5, Pseudowires    |          |
   |           | [VCCV]                               |          |
   |           +--------------------------------------+----------+
   |           | Bidirectional Forwarding Detection   | RFC 792, September 1981.

   [ICMPv6]      Conta, A., Deering, S., and M. Gupta, "Internet Control
                 Message Protocol (ICMPv6) 5885 |
   |           | for the Internet Protocol
                 Version 6 (IPv6) Specification", RFC 4443, March 2006.

   [MPLS-P2MP]   Yasukawa, S., Farrel, A., King, D., Nadeau, T.,
                 "Operations and Management (OAM) Requirements for
                 Point-to-Multipoint MPLS Networks", RFC 4687,
                 September 2006.

   [ICMP-Ext]    Bonica, R., Gan, D., Tappan, D., Pignataro, C., "ICMP
                 Extensions for Multiprotocol Label Switching", RFC
                 4950, August 2007.

   [ICMP-MP]     Bonica, R., Gan, D., Tappan, D., Pignataro, C.,
                 "Extended ICMP to Support Multi-Part Messages", Pseudowire Virtual Circuit   |          |
   |           | Connectivity Verification (VCCV)     |          |
   |           | [BFD-VCCV]                           |          |
   |           +--------------------------------------+----------+
   |           | Using the Generic Associated Channel | RFC
                 4884, April 2007.

   [ICMP-Int]    Atlas, A., Bonica, R., Pignataro, C., Shen, N., Rivers,
                 JR., "Extending ICMP 6423 |
   |           | Label for Interface and Next-Hop
                 Identification", Pseudowire in the MPLS     |          |
   |           | Transport Profile (MPLS-TP)          |          |
   |           | [PW-G-ACh]                           |          |
   |           +--------------------------------------+----------+
   |           | Pseudowire (PW) Operations,          | RFC 5837, April 2010.

   [TCPIP-Tools] Kessler, G., Shepard, S., "A Primer On Internet 6310 |
   |           | Administration, and
                 TCP/IP Tools Maintenance (OAM)|          |
   |           | Message Mapping [PW-Map]             |          |
   +-----------+--------------------------------------+----------+
   |OWAMP and Utilities",  | A One-way Active Measurement Protocol| RFC 2151, June 1997.

   [NetTools]    Stine, R., "FYI on a Network Management Tool Catalog:
                 Tools for Monitoring and Debugging TCP/IP Internets
                 and Interconnected Devices", 4656 |
   |TWAMP      | [OWAMP]                              |          |
   |           +--------------------------------------+----------+
   |           | A Two-Way Active Measurement Protocol| RFC 1147, April 1990.

   [IPPM-FW]     Paxson, V., Almes, G., Mahdavi, J., and Mathis, M.,
                 "Framework 5357 |
   |           | [TWAMP]                              |          |
   |           +--------------------------------------+----------+
   |           | Framework for IP Performance Metrics", Metrics | RFC 2330, May
                 1998.

   [IPPM-Con]    Mahdavi, J., Paxson, V., "IPPM 2330 |
   |           | [IPPM-FW]                            |          |
   |           +--------------------------------------+----------+
   |           | IPPM Metrics for Measuring
                 Connectivity",           | RFC 2678, September 1999.

   [IPPM-1DM]    Almes, G., Kalidindi, S., Zekauskas, M., "A 2678 |
   |           | Connectivity [IPPM-Con]              |          |
   |           +--------------------------------------+----------+
   |           | A One-way Delay Metric for IPPM", IPPM      | RFC 2679, September 1999.

   [IPPM-1LM]    Almes, G., Kalidindi, S., Zekauskas, M., "A 2679 |
   |           | [IPPM-1DM]                           |          |
   |           +--------------------------------------+----------+
   |           | A One-way Packet Loss Metric for IPPM", IPPM| RFC 2680, September
                 1999.

   [IPPM-2DM]    Almes, G., Kalidindi, S., Zekauskas, M., "A 2680 |
   |           | [IPPM-1LM]                           |          |
   |           +--------------------------------------+----------+
   |           | A Round-trip Delay Metric for IPPM", RFC 2681, September 1999.

   [OWAMP]       Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and
                 Zekauskas, M., "A One-way Active Measurement Protocol
                 (OWAMP)", IPPM   | RFC 4656, September 2006.

   [TWAMP]       Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and
                 Babiarz, J., "A Two-Way Active Measurement Protocol
                 (TWAMP)", 2681 |
   |           | [IPPM-2DM]                           |          |
   |           +--------------------------------------+----------+
   |           | Packet Reordering Metrics            | RFC 5357, October 2008.

   [BFD]         Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD)", 4737 |
   |           | [Reorder]                            |          |
   |           +--------------------------------------+----------+
   |           | A One-Way Packet Duplication Metric  | RFC 5880, June 2010.

   [BFD-IP]      Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD) 5560 |
   |           | [Dup]                                |          |
   +-----------+--------------------------------------+----------+
   |TRILL OAM  | Requirements for IPv4 and IPv6 (Single Hop)", Operations,         | RFC 5881, June
                 2010.

   [BFD-Gen]     Katz, D., Ward, D., "Generic Application 6905 |
   |           | Administration, and Maintenance (OAM)|          |
   |           | in Transparent Interconnection of
                 Bidirectional Forwarding Detection (BFD)", RFC 5882,
                 June 2010.

   [BFD-Multi]   Katz, D., Ward, D., "Bidirectional Forwarding Detection
                 (BFD)    |          |
   |           | Lots of Links (TRILL)                |          |
   +-----------+--------------------------------------+----------+
                 Table 5 Summary of IETF OAM Related RFCs

A.2. List of Selected Non-IETF OAM Documents

   In addition to the OAM mechanisms defined by the IETF, the IEEE and
   ITU-T have also defined various OAM mechanisms that focus on
   Ethernet, and various other transport network environments. These
   various mechanisms, defined by the three standard organizations, are
   often tightly coupled, and have had a mutual effect on each other.
   The ITU-T and IETF have both defined OAM mechanisms for MPLS LSPs,
   [ITU-T-Y1711] and [LSP-Ping]. The following OAM standards by the IEEE
   and ITU-T are to some extent linked to IETF OAM mechanisms listed
   above and are mentioned here only as reference material:

   o OAM mechanisms for Multihop Paths", RFC 5883, June 2010.

   [BFD-LSP]     Aggarwal, R., Kompella, K., Nadeau, T., Layer 2 have been defined by the ITU-T in
      [ITU-T-Y1731], and Swallow,
                 G., "Bidirectional Forwarding Detection (BFD) by the IEEE in 802.1ag [IEEE802.1Q] . The IEEE
      802.3 standard defines OAM for one-hop Ethernet links
      [IEEE802.3ah].

   o The ITU-T has defined OAM for MPLS
                 Label Switched Paths (LSPs)", RFC 5884, June 2010.

   [BFD-VCCV]    Nadeau, T., Pignataro, C., "Bidirectional Forwarding
                 Detection (BFD) LSPs in [ITU-T-Y1711], and
      MPLS-TP OAM in [ITU-G8113.1] and [ITU-G8113.2].

   It should be noted that these non-IETF documents deal in many cases
   with OAM functions below the IP layer (Layer 2, Layer 2.5) and in
   some cases operators use a multi-layered OAM approach, which is a
   function of the way their networks are designed.

   Table 6 summarizes some of the main OAM standards published by non-
   IETF standard organizations. This document focuses on IETF OAM
   standards, but these non-IETF standards are referenced in this
   document where relevant.

   +-----------+--------------------------------------+---------------+
   |           | Title                                |Standard/Draft |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | Operation & Maintenance mechanism    | ITU-T Y.1711  |
   |MPLS OAM   | for MPLS networks [ITU-T-Y1711]      |               |
   |           +--------------------------------------+---------------+
   |           | Assignment of the Pseudowire Virtual Circuit
                 Connectivity Verification (VCCV)", 'OAM Alert Label'  | RFC 5885, June
                 2010.

   [TP-OAM-FW]   Busi, I., Allan, D., "Operations, Administration 3429      |
   |           | for Multiprotocol Label Switching    |               |
   |           | Architecture (MPLS) Operation and    |               |
   |           | Maintenance (OAM) Functions          |               |
   |           | [OAM-Label]                          |               |
   |           |                                      |               |
   |           |  Note: although this is an IETF      |               |
   |           |  document, it is listed as one of the|               |
   |           |  non-IETF OAM standards, since it    |               |
   |           |  was defined as a complementary part |               |
   |           |  of ITU-T Y.1711.                    |               |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | Operations, administration and       |ITU-T G.8113.2 |
   |MPLS-TP OAM| Maintenance Framework for MPLS-based Transport
                 Networks ", RFC 6371, September 2011.

   [TP-CC-CV]    Allan, D., Swallow, G., Drake, J., "Proactive
                 Connectivity Verification, Continuity Check and Remote
                 Defect indication mechanisms for MPLS Transport Profile", RFC
                 6428, November 2011.

   [OnDemand-CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS
                 On-Demand Connectivity Verification and Route
                 Tracing", RFC 6426, November 2011.

   [MPLS-LM-DM]  Frost, D., Bryant, S., "Packet Loss and Delay
                 Measurement MPLS-TP   |               |
   |           | networks using the tools defined for |               |
   |           | MPLS Networks", RFC 6374, September
                 2011.

   [TP-LM-DM]    Frost, D., Bryant, S., "A Packet Loss and Delay
                 Measurement Profile [ITU-G8113.2]                   |               |
   |           |                                      |               |
   |           |  Note: this document describes the   |               |
   |           |  OAM toolset defined by the IETF for MPLS-Based Transport
                 Networks", RFC 6375, September 2011.

   [TP-Fault]    Swallow, G., Fulignoli, A., Vigoureux, M., Boutros, S.,
                 "MPLS Fault Management |               |
   |           |  MPLS-TP, whereas ITU-T G.8113.1     |               |
   |           |  describes the OAM toolset defined   |               |
   |           |  by the ITU-T.                       |               |
   |           +--------------------------------------+---------------+
   |           | Operations, Administration, Administration and       |ITU-T G.8113.1 |
   |           | Maintenance (OAM)", RFC 6427, November 2011.

   [Lock-Loop]   Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux,
                 M., Dai, X., "MPLS mechanism for MPLS-TP in |               |
   |           | Packet Transport Profile Lock Instruct and
                 Loopback Functions", RFC 6435, November 2011.

   [ITU-T-CT]    Betts, M., "Allocation Network (PTN)       |               |
   |           +--------------------------------------+---------------+
   |           | Allocation of a Generic Associated   | RFC 6671      |
   |           | Channel Type for ITU-T MPLS Transport Transport|               |
   |           | Profile Operation, Maintenance, and  |               |
   |           | Administration (MPLS-TP OAM)", RFC
                 6671, November 2012.

   [PW-Map]      M. Aissaoui, P. Busschbach, L. Martini, M. Morrow, T.
                 Nadeau, "Pseudowire (PW) Operations, Administration,
                 and Maintenance (OAM) Message Mapping", RFC 6310, July
                 2011.

   [PW-G-ACh]    Li, H., Martini, L., He, J., Huang, F., "Using the
                 Generic Associated Channel Label for Pseudowire in the
                 MPLS Transport Profile (MPLS-TP)", RFC 6423, November
                 2011.

7.2. Informative References

   [OAM-Def]     Andersson, L., Van Helvoort, H., Bonica, R., Romascanu,
                 D., Mansfield, S., "Guidelines for the use OAM)         |               |
   |           | [ITU-T-CT]                           |               |
   |           |                                      |               |
   |           |  Note: although this is an IETF      |               |
   |           |  document, it is listed as one of the the|               |
   |           |  non-IETF OAM
                 acronym in the IETF ", RFC 6291, June 2011.

   [OAM-Analys]  Sprecher, N., Fang, L., "An Overview standards, since it    |               |
   |           |  was defined as a complementary part |               |
   |           |  of the ITU-T G.8113.1.                  |               |
   +-----------+--------------------------------------+---------------+
   |ITU-T      | OAM Tool
                 Set for  MPLS based Transport Networks", RFC 6669,
                 July 2012.

   [TP-Term]     Van Helvoort, H., Andersson, L., Sprecher, N., "A
                 Thesaurus for the Terminology used in Multiprotocol
                 Label Switching Transport Profile (MPLS-TP)
                 drafts/RFCs Functions and ITU-T's Transport Network
                 Recommendations", work-in-progress, draft-ietf-mpls-
                 tp-rosetta-stone, July 2012.

   [IEEE802.1ag] Mechanisms for     | ITU-T Y.1731  |
   |Ethernet   | Ethernet-based Networks              |               |
   |OAM        | [ITU-T-Y1731]                        |               |
   +-----------+--------------------------------------+---------------+
   |IEEE       | Connectivity Fault Management        | IEEE 802.1ag  |
   |CFM        | [IEEE802.1Q]                         |               |
   |           |                                      |               |
   |           |  Note: CFM was originally published  |               |
   |           |  as IEEE 802.1Q, "IEEE Standard for Local 802.1ag, but is now         |               |
   |           |  incorporated in the 802.1Q standard.|               |
   +-----------+--------------------------------------+---------------+
   |IEEE       | Management of Data Driven and metropolitan
                 area networks - Data   | IEEE 802.1ag  |
   |DDCFM      | Dependent Connectivity Faults        |               |
   |           | [IEEE802.1Q]                         |               |
   |           |                                      |               |
   |           |  Note: DDCFM was originally published|               |
   |           |  as IEEE 802.1Qaw, but is now        |               |
   |           |  incorporated in the 802.1Q standard.|               |
   +-----------+--------------------------------------+---------------+
   |IEEE       | Media Access Control (MAC) Bridges and
                 Virtual Bridged Local Area Networks", October 2012.

   [ITU-T-Y1731] ITU-T Recommendation G.8013/Y.1731, "OAM Functions Parameters,     | IEEE 802.3ah  |
   |802.3      | Physical Layers, and
                 Mechanisms for Ethernet-based Networks", July 2011.

   [ITU-T-Y1711] ITU-T Recommendation Y.1711, "Operation & Maintenance
                 mechanism Management      |               |
   |link level | Parameters for MPLS networks", February 2004. Subscriber Access     |               |
   |OAM        | Networks [IEEE802.3ah]               |               |
   |           |                                      |               |
   |           |  Note: link level OAM was originally |               |
   |           |  defined in IEEE 802.3, "IEEE Standard for Information technology -
                 Local and metropolitan area networks - Carrier sense
                 multiple access with collision detection (CSMA/CD)
                 access method and physical layer specifications",
                 clause 57, December 2008.

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

   [ITU-G8113.2] ITU-T Recommendation G.8113.2/Y.1372.2, "Operations,
                 administration 802.3ah, and maintenance mechanisms for MPLS-TP
                 networks using is now |               |
   |           |  incorporated in the tools defined for MPLS", November
                 2012.

   [ITU-G8113.1] ITU-T Recommendation G.8113.1/Y.1372.1, "Operations,
                 Administration and Maintenance mechanism for MPLS-TP 802.3 standard. |               |
   +-----------+--------------------------------------+---------------+
         Table 6 Non-IETF OAM Standards Mentioned in Packet Transport Network (PTN)", November 2012. this Document

Authors' Addresses

   Tal Mizrahi
   Marvell
   6 Hamada St.
   Yokneam, 20692
   Israel

   Email: talmi@marvell.com

   Nurit Sprecher
   Nokia Siemens Networks
   3 Hanagar St. Neve Ne'eman B
   Hod Hasharon,   45241
   Israel

   Email: nurit.sprecher@nsn.com

   Elisa Bellagamba
   Ericsson
   6 Farogatan St.

   Stockholm,   164 40
   Sweden

   Phone: +46 761440785
   Email: elisa.bellagamba@ericsson.com

   Yaacov Weingarten
   34 Hagefen St.
   Karnei Shomron,   4485500
   Israel

   Email: wyaacov@gmail.com