Subject: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An Overview of Operations, Administration, and Maintenance (OAM) Mechanisms) to Informational RFC

From: The IESG <[email-masked]>
Date: Fri, 11 Jan 2013 11:36:16 -0800

The IESG has received a request from the Operations and Management Area
Working Group WG (opsawg) to consider the following document:
- 'An Overview of Operations, Administration, and Maintenance (OAM)
   Mechanisms'
  <draft-ietf-opsawg-oam-overview-08.txt> as Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
[email-masked] mailing lists by 2013-01-25. Exceptionally, comments may be
sent to [email-masked] instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

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 protocols.

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

The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-opsawg-oam-overview/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-opsawg-oam-overview/ballot/

No IPR declarations have been submitted directly on this I-D.

---

From: Benoit Claise <[email-masked]>
Date: Mon, 14 Jan 2013 17:52:15 +0100

draft-ietf-opsawg-oam-overview authors,

Here is my feedback on this document.

1.
Is this document in line with 
http://tools.ietf.org/html/draft-ietf-trill-oam-req-04?
* For example, the following definitions could be reused.

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

    Defect: The term Defect refers to an interruption in the normal
    operation, such that over a period of time no packets are delivered
    successfully.

    Failure: The term Failure refers to the termination of the required
    function over a longer period of time. Persistence of a defect for a
    period of time is interpreted as a failure.

* For example, on the basic abstract
Abstract

Abstract (draft-ietf-trill-oam-req-04)

    OAM (Operations, Administration and Maintenance) is a general term
    used to identify functions and toolsets to troubleshoot and monitor
    networks. This document presents, OAM Requirements applicable to
    TRILL.

So, as an example: does OAM include function?
I advice to review draft-ietf-trill-oam-req-04

2.
draft-ietf-trill-oam is not mentioned, while the abstract mentions:
    This document presents an overview of the OAM mechanisms that have
    been defined and are currently being defined by the IETF.
Search for OAM in the current draft names (https://datatracker.ietf.org/), and you will find many references.
Ok, I see later on:	
    This document focuses on IETF
    documents that have been published as RFCs, while other ongoing OAM-
    related work is outside the scope.
Ok, fine then: we don't need a reference to all the drafts.
However, draft-ietf-trill-oam is closed to be a RFC, and should be mentioned.

3.
Section 1
    The term OAM in this document refers to Operations, Administration
    and Maintenance [OAM-Def  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#ref-OAM-Def>], focusing on the forwarding plane of OAM.
What does it mean "focusing on the forwarding plane of OAM"?
Do you take a subset of the definition for this document?
Btw, I don't see a definition in the terminology section.
In section 2.2.3
    A Maintenance Point (MP) is a functional entity that is defined at a
    node in the network, and either initiates or reacts to OAM messages.
Which plane is MP?

4.
Section 1, Introduction
"Hence, management aspects are outside the scope of this document."
I don't understand which management aspects we speak about here.

5.
Clarifying question regarding 1.2
If speak about OWAMP or TWAMP 'synthetic traffic), is that data plane, 
control plane, or management plane?
Note that I found later on in the draft:

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

Interestingly enough, after reading the document, I reviewed 
http://datatracker.ietf.org/doc/draft-ietf-opsawg-oam-overview/ballot/, 
and saw the same feedback from Stewart Bryant:

    Provide a clear view of OAM functionality and its relationship
    to various "planes" of networking (data plane, control plane,
    management plane). In particular, the importance of
    fate-sharing of OAM and user traffic flows in packet networks
    should be explained.

6.

I see a multiplication of "plane" terms in the IETF document, and in this document in particular.
I could find: forwarding plane, management plane, control plane, data plane, user plane, and test plane.
Way too many.
Please be consistent

7.

    Table 1 summarizes the IETF OAM related RFCs discussed in this
    document.

    Table 2 summarizes the OAM standards mentioned in this document.

You need to change the Table 2 description. Do you want to say something along the lines of:
    Table 2 summarizes the OAM standards specified by other Standard Development Organization
    (SDO) than the IETF, along with IETF references where applicable.

8.
Section 2.2.1
    For a formal definition of each term, refer to the references at the end of
    this document.
Without a reference to a specific RFC, this is the type of statement which is not useful: you have 5 pages of references.
You position this document as "An Overview of  Operations, Administration, and Maintenance (OAM) Mechanisms", but you tell the reader: "if you want to know about the terms,
just read first all references!"

9.
You specify some terms and some OAM categories,
    2.2.2  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#section-2.2.2>. OAM Maintenance Entities ..........................13  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#page-13>
          2.2.3  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#section-2.2.3>. OAM Maintenance Points ............................14  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#page-14>
          2.2.4  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#section-2.2.4>. Proactive and On-demand activation ................15  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#page-15>
          2.2.5  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#section-2.2.5>. Connectivity Verification and Continuity Checks ...15  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#page-15>
          2.2.6  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#section-2.2.6>. Failures ..........................................15  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#page-15>
... but you don't use them in the section 3

Just_one_example with section 3.2.2
-
    o Demand mode: 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
Instead of liveness, you have defined Connectivity Verification and Continuity Checks  in section 2.2.5
- OLD:
    Each of the end-points of the monitored path maintains its own
    session identification
NEW:
    Each of the MEP maintains its own session identification
OR NEW (actually I don't know)
    Each of the MP maintains its own session identification
- OLD
	A BFD echo packet is sent to a peer system
Peer system = MEP, MP, or something else?
- etc...

10.
This document is composed of a list of OAM content and references, but I'm really missing the document "scope and target audience".
When we did RFC 6632, which is the companion document, we hadhttp://tools.ietf.org/html/rfc6632#section-1.1
  
    The target audience of the document is, on the one hand, IETF working
    groups, which aim to select appropriate standard management protocols
    and data models to address their needs concerning network management.
    On the other hand, the document can be used as an overview and
    guideline by non-IETF Standards Development Organizations (SDOs)
    planning to use IETF management technologies and data models for the
    realization of management applications.  The document can also be
    used to initiate a discussion between the bodies with the goal to
    gather new requirements and to detect possible gaps.  Finally, this
    document is directed to all interested parties that seek to get an
    overview of the current set of the IETF network management protocols
    such as network administrators or newcomers to the IETF.

You should have something similar.

11.
Section 3.6.1, put the paragraph 2 at the end of the section. The "alternative" in the following sentence would then make sense
    Alternative protocols for performance measurement are defined, for
    example, in MPLS-TP OAM ([MPLS-LM-DM  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#ref-MPLS-LM-DM>], [TP-LM-DM  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#ref-TP-LM-DM>]), and in Ethernet
    OAM [ITU-T-Y1731  <http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-08#ref-ITU-T-Y1731>].

My conclusions: this document still needs some work

Regards, Benoit

---

From: Benoit Claise <[email-masked]>
Date: Tue, 15 Jan 2013 15:48:41 +0100

Some more feedback, send on behalf of Al Morton.

Regards, Benoit

=================================================
Hi Benoit,

Here are some additional comments, just checking a few things
I know a little about.

Al

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

1.1. The Building Blocks of OAM
...
    o Performance Monitoring:
       Consists of 3 main functions

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

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

         o Throughput measurement - monitors the throughput of a
           connection.

>>> Apparently, no OAM tool  currently measures Throughput,
     because no such tool is cited in the memo (and the term "throughput"
     never appears again).  my guess is that there was some reference to
     RFC 2544 that has now been removed. Remove Throughput from the list.

1.3 OAM Toolsets
...
    o OWAMP and TWAMP:
       The One Way Active Measurement Protocol (OWAMP) and the Two Way
       Active Measurement Protocols (TWAMP) are two protocols defined in
       the IP Performance Metrics (IPPM) working group in the IETF. These
       protocols allow delay and packet loss measurement in IP networks.

>>> and Delay variation,  duplication, reordering, etc. (all the metrics limited tools
     completely ignore).

1.4 IETF OAM Documents

>>> Expand Table 1 as noted  above, to include all the metrics they missed.

3.6.1
...
    TWAMP [TWAMP] is a similar protocol that enables measurement of
>>> both one-way and
    two-way (round trip) characteristics.

>>> sentence below is  simply not true, because the authors did not understand
    the one-way measurement capability:
    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.
>>> go back and read the  memo...

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.

+-----------+-------+--------+--------+-----------+-------+--------+
    | Standard |Continu|Connecti|Path    |Defect     |Perform|Other   |
    |           |ity    |vity |Discover|Indications|ance   |Function|
    |           |Check |Verifica|y       |           |Monitor|s       |
    |           |       |tion |        |           |ing    |        |
+-----------+-------+--------+--------+-----------+-------+--------+
...
    + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
    |OWAMP and  |       | |        |           |-Delay |        |
    |TWAMP      |  Yes  |  Yes |        |           | measur|        |
    |           |       | |        |           | ement |        |
    |           |       | |        |           |-Packet|        |
    |           |       | |        |           | loss  |        |
    |           |       | |        |           | measur|        |
    |           |       | |        |           | ement |        |
+-----------+-------+--------+--------+-----------+-------+--------+
                      Table 3 Summary of OAM Functions

>>> Both Continuity Check  and Connectivity Verification are tested and
confirmed by establishing the *WAMP Control Protocol TCP connection,
so this should be indicated the table.

> http://datatracker.ietf.org/doc/draft-ietf-opsawg-oam-overview/ballot/, and 
> saw the same feedback from Stewart Bryant:
>
>> sent [email-masked]  instead. In either case, please retain the

---

From: Benoit Claise <[email-masked]>
Date: Fri, 18 Jan 2013 17:06:20 +0100

Here is Tom Nadeau's feedback, forwarded with permission:

Regards, Benoit

==============

Some general comments:

 1. I did not find any discussion around use of configuration within OAM
    mechanisms. This is clearly something that is happening in groups
    like PWE3 and CCAMP. The motivation for this should be explained and
    documented to at least guide these efforts.

2. There is no real discussion around the security aspects of these 
tools. Should there be?

3. While the document provides a nice taxonomy of various OAM tools, it 
does not really discuss the techniques for using them. I do not expect 
anything in detail, but it is not obvious that many of these tools can 
be orchestrated to form a "toolset" that can be used to do multi-layer 
OAM functions for services such as carrier Ethernet over VPLS over MPLS, 
for example.

4. It might be useful to at least mention in the performance metrics 
section, a discussion around the accuracy of these tools and how it 
depends on scale, implementation and network configurations.

My detailed comments inline starting with TOM:

--Tom

    Expires: July 2013                                Nokia Siemens Networks
        E. Bellagamba
             Ericsson
        Y. Weingarten

      January 9, 2013

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

    Abstract

        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 protocols.

    Status of this Memo

        This Internet-Draft is submitted to IETF in full conformance
    with the
        provisions of BCP 78 and BCP 79.

        Internet-Drafts are working documents of the Internet Engineering
        Task Force (IETF), its areas, and its working groups.  Note that
        other groups may also distribute working documents as Internet-
        Drafts.

        Internet-Drafts are draft documents valid for a maximum of six
    months
        and may be updated, replaced, or obsoleted by other documents at any
        time.  It is inappropriate to use Internet-Drafts as reference
        material or to cite them other than as "work in progress."

        The list of current Internet-Drafts can be accessed at
        http://www.ietf.org/ietf/1id-abstracts.txt.

        The list of Internet-Draft Shadow Directories can be accessed at
        http://www.ietf.org/shadow.html.

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

    Mizrahi, et al.         Expires July 9, 2013        [Page 1]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    Copyright Notice

        Copyright (c) 2013 IETF Trust and the persons identified as the
        document authors. All rights reserved.

        This document is subject to BCP 78 and the IETF Trust's Legal
        Provisions Relating to IETF Documents
        (http://trustee.ietf.org/license-info) in effect on the date of
        publication of this document. Please review these documents
        carefully, as they describe your rights and restrictions with
    respect
        to this document. Code Components extracted from this document must
        include Simplified BSD License text as described in Section 4.e of
        the Trust Legal Provisions and are provided without warranty as
        described in the Simplified BSD License.

    Table of Contents

        1. Introduction ................................................. 3
           1.1. The Building Blocks of OAM .............................. 3
           1.2. Forwarding Plane vs. Management Plane ................... 4
           1.3. The OAM toolsets ........................................ 4
           1.4. IETF OAM Documents ...................................... 6
           1.5. Non-IETF OAM Documents ................................. 10
        2. Basic Terminology ........................................... 12
           2.1. Abbreviations .......................................... 12
           2.2. Terminology used in OAM Standards ...................... 13
              2.2.1. General Terms ..................................... 13
              2.2.2. OAM Maintenance Entities .......................... 13
              2.2.3. OAM Maintenance Points ............................ 14
              2.2.4. Proactive and On-demand activation ................ 15
              2.2.5. Connectivity Verification and Continuity Checks ... 15
              2.2.6. Failures .......................................... 15
        3. OAM Tools ................................................... 16
           3.1. IP Ping and Traceroute ................................. 16
              3.1.1. Ping .............................................. 16
              3.1.2. Traceroute......................................... 16
           3.2. Bidirectional Forwarding Detection (BFD) ............... 17
              3.2.1. Overview .......................................... 17
              3.2.2. BFD Control ....................................... 17
              3.2.3. BFD Echo .......................................... 18
           3.3. MPLS OAM ............................................... 18
           3.4. MPLS-TP OAM ............................................ 19
              3.4.1. Overview .......................................... 19
              3.4.2. Generic Associated Channel ........................ 19
              3.4.3. MPLS-TP OAM Toolset ............................... 20
                 3.4.3.1. Continuity Check and Connectivity Verification 20

    Mizrahi, et al.         Expires July 9, 2013        [Page 2]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

                 3.4.3.2. Route Tracing ................................ 21
                 3.4.3.3. Lock Instruct ................................ 21
                 3.4.3.4. Lock Reporting ............................... 21
                 3.4.3.5. Alarm Reporting .............................. 21
                 3.4.3.6. Remote Defect Indication ..................... 22
                 3.4.3.7. Client Failure Indication .................... 22
                 3.4.3.8. Packet Loss Measurement (LM) ................. 22
                 3.4.3.9. Packet Delay Measurement (DM) ................ 22
           3.5. PWE3 OAM ............................................... 23
              3.5.1. PWE3 OAM using Virtual Circuit Connectivity
    Verification
              (VCCV) ................................................... 23
              3.5.2. PWE3 OAM using G-ACh .............................. 24
           3.6. OWAMP and TWAMP......................................... 24
              3.6.1. Overview .......................................... 24
              3.6.2. Control and Test Protocols ........................ 24
              3.6.3. OWAMP ............................................. 25
              3.6.4. TWAMP ............................................. 26
           3.7. Summary of OAM Functions ............................... 26
        4. Security Considerations ..................................... 27
        5. IANA Considerations ......................................... 27
        6. Acknowledgments ............................................. 27
        7. References .................................................. 28
           7.1. Normative References ................................... 28
           7.2. Informative References ................................. 31

    1. Introduction

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

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

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

TOM: This is a curious sentence to me since to me, OAM is management, or 
a subset of it.   Also, if you look at the referenced documents, there 
are many indirect references to MIBs, Netconf, etc... making this 
sentence further confusing. It might be helpful to explain more clearly 
that the authors here intended to not cover those things explicitly 
rather than grouping them arbitrarily under the definition of 
"management aspects"  Further, to clarify, it might be useful to expand 
on what "forwarding plane" is here just to be clear.   That is, is this 
"in band" or "out-of band" or both? Some of the tools referred to here 
also are part of the control AND data planes.

        An OAM protocol is run in the context of a Maintenance Domain,
        consisting of two or more nodes that run the OAM protocol, referred
        to as Maintenance Points (MP).

        This subsection provides a brief summary of the common tools used by
        OAM protocols. An OAM protocol typically supports one or more of the
        tools described below.

    Mizrahi, et al.         Expires July 9, 2013        [Page 3]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        o Continuity Checking (CC):
           Used for verifying the liveness of a connection between two MPs.

        o Connectivity Verification (CV):
           Allows an MP to check whether it 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 the path to the peer MP. When a
           connection fails, this mechanism also allows the MP to detect the
           location of the failure.

TOM: The definition calls this "path discovery" but then talks about 
tracing routes. A better way of describing this in the paragraph would 
be that there I a use of path tracing in order to discover (or 
re-discover) paths that have been changed, created or destroyed.

TOM: Along with the discussion above around path trace/discovery, it is 
imperative that paths be discovered (one way or another) in order to 
successfully d performance monitoring on those paths.

    1.2. Forwarding Plane vs. Management Plane

        While the OAM tools may, and quite often do, work in conjunction
    with
        a control-plane or management plane, they are usually defined to be
        independent of the control-plane.  The OAM tools communicate
    with the
        management plane to raise alarms, and often the on-demand tools may
        be activated by the management, e.g. to locate 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 that are used for OAM.

TOM: What about the data plane? For example, the GACH OAM type is such 
an example. VCCV also operates within the data plane after its 
configuration capabilities have been signaled.  It should also be 
mentioned that it is imperative that when required, OAM tools are 
capable of testing the actual data plane in as much accuracy as 
possible, but that they all should note how accurate.   Not all OAM 
tools are created equal.

    1.3. The OAM toolsets

        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). While
        OAM mechanisms that are applicable to other technologies exist, they

    Mizrahi, et al.         Expires July 9, 2013        [Page 4]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        are beyond the scope of this memo. This document focuses on IETF
        documents that have been published as RFCs, while other ongoing 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 a very simple and common application for failure
    diagnosis

TOM: I am not sure the term "common" is necessary.

           that uses ICMP Echo requests, as defined in [ICMPv4], and
           [ICMPv6].
           Traceroute ([TCPIP-Tools], [NetTools]) is 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.

        o BFD:
           Bidirectional Forwarding Detection (BFD) 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.

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

        o MPLS-TP OAM:
           MPLS-TP OAM is defined in a set of RFCs. 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 1.4.

        o PWE3 OAM:
           The PWE3 OAM architecture defines control channels that support
           the use of existing IETF OAM tools to be used for a pseudowire
           (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.

        o OWAMP and TWAMP:
           The One Way Active Measurement Protocol (OWAMP) and the Two Way
           Active Measurement Protocols (TWAMP) are two protocols defined in
           the IP Performance Metrics (IPPM) working group in the IETF.
    These
           protocols allow delay and packet loss measurement in IP networks.

    Mizrahi, et al.         Expires July 9, 2013        [Page 5]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        This document summarizes the OAM mechanisms defined by the IETF. We
        first present a comparison of the terminology used in various OAM
        standards, and then summarize the OAM functions that each OAM
        standard provides.

    1.4. IETF OAM Documents

        The table includes a "Type" column, specifying the nature of each of
        the listed documents:

        o Tool: documents that define an OAM tool or mechanism.

        o Prof.: documents that define a profile or a variant for an OAM
           tool that is defined in other documents.

        o Inf.: documents that define an infrastructure that is used by OAM
           tools.

        o Misc.: other OAM related documents, e.g., OAM requirement and
           framework documents.

      +-----------+--------------------------------------+-----+----------+
        |           | Title  |Type | RFC      |
      +-----------+--------------------------------------+-----+----------+
        |IP Ping and| Internet Control Message Protocol  |Tool | RFC 792  |
        |Traceroute | [ICMPv4]                             |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Internet Control Message Protocol  |Tool | RFC 4443 |
        |           | (ICMPv6) for the Internet Protocol   |     |      
        |
        |           | Version 6 (IPv6) Specification       |     |      
        |
        |           | [ICMPv6]                             |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | A Primer On Internet and TCP/IP  |Tool | RFC 2151 |
        |           | Tools and Utilities [TCPIP-Tools]    |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | FYI on a Network Management Tool |Tool | RFC 1147 |
        |           | Catalog: Tools for Monitoring and    |     |      
        |
        |           | Debugging TCP/IP Internets and       |     |      
        |
        |           | Interconnected Devices [NetTools]    |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Extended ICMP to Support Multi-Part  |Tool | RFC
    4884 |

    Mizrahi, et al.         Expires July 9, 2013        [Page 6]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        |           | Messages [ICMP-MP]                   |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | ICMP Extensions for Multiprotocol  |Tool | RFC 4950 |
        |           | Label Switching [ICMP-Ext]           |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Extending ICMP for Interface 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 and IPv6 (Single Hop) |     |      
        |
        |           | [BFD-IP]                             |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Generic Application 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 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    |     |      
        |
        |           | and Management (OAM) [MPLS-OAM-FW]   |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Detecting Multi-Protocol Label |Tool | RFC 4379 |
        |           | Switched (MPLS) Data Plane Failures  |     |      
        |
        |           | [LSP-Ping]                           |     |      
        |

    Mizrahi, et al.         Expires July 9, 2013        [Page 7]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        | +--------------------------------------+-----+----------+
        |           | Operations and Management (OAM)  |Misc.| RFC 4687 |
        |           | Requirements for Point-to-Multipoint |     |      
        |
        |           | MPLS Networks [MPLS-P2MP]            |     |      
        |
      +-----------+--------------------------------------+-----+----------+
        |MPLS-TP    | Requirements for OAM 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 |
        |           | 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 and Delay Measurement  |Prof.| RFC
    6375 |
        |           | Profile for MPLS-Based Transport     |     |      
        |
        |           | Networks [TP-LM-DM]                  |     |      
        |
      +-----------+--------------------------------------+-----+----------+
        |PWE3 OAM   | Pseudowire Virtual Circuit |Inf. | RFC 5085 |
        |           | Connectivity Verification (VCCV):    |     |      
        |
        |           | A Control Channel for Pseudowires    |     |      
        |
        |           | [VCCV]                               |     |      
        |

    Mizrahi, et al.         Expires July 9, 2013        [Page 8]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        | +--------------------------------------+-----+----------+
        |           | Bidirectional Forwarding Detection |Prof.| RFC 5885 |
        |           | for the Pseudowire Virtual Circuit   |     |      
        |
        |           | Connectivity Verification (VCCV)     |     |      
        |
        |           | [BFD-VCCV]                           |     |      
        |
        | +--------------------------------------+-----+----------+
        |           | Using the Generic Associated Channel |Inf. | RFC
    6423 |
        |           | Label for Pseudowire in 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 of IETF OAM Related RFCs

    Mizrahi, et al.         Expires July 9, 2013        [Page 9]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    1.5. 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 Ethernet based networks have been defined by
           both the ITU-T in [ITU-T-Y1731], and by the IEEE in
    [IEEE802.1ag].
           The IEEE 802.3 standard defines OAM for one-hop Ethernet links
           [IEEE802.3ah].

        o The ITU-T has defined OAM for MPLS LSPs in [ITU-T-Y1711], and
           MPLS-TP OAM in [ITU-G8113.1] and [ITU-G8113.2].

        Table 2 summarizes the OAM standards mentioned in this document.
    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 of the 'OAM Alert Label'  | RFC 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 mechanisms for MPLS-TP   |               |

    Mizrahi, et al.         Expires July 9, 2013       [Page 10]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        |           | networks using the tools defined for |               |
        |           | MPLS [ITU-G8113.2]                   |               |
        |           |                                      |               |
        |           |  Note: this document describes the   |               |
        |           |  OAM toolset defined by the IETF for |               |
        |           |  MPLS-TP, whereas ITU-T G.8113.1     |               |
        |           |  describes the OAM toolset defined   |               |
        |           |  by the ITU-T.                       |               |
        | +--------------------------------------+---------------+
        |           | Operations, Administration and |ITU-T G.8113.1 |
        |           | Maintenance mechanism for MPLS-TP in |               |
        |           | Packet Transport Network (PTN)       |               |
        | +--------------------------------------+---------------+
        |           | Allocation of a Generic Associated   | RFC 6671      |
        |           | Channel Type for ITU-T MPLS Transport|               |
        |           | Profile Operation, Maintenance, and  |               |
        |           | Administration (MPLS-TP OAM)         |               |
        |           | [ITU-T-CT]                           |               |
        |           |                                      |               |
        |           |  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 G.8113.1.                  |               |
      +-----------+--------------------------------------+---------------+
        |ITU-T      | OAM Functions and Mechanisms for |[ITU-T-Y1731]  |
        |Ethernet   | Ethernet-based Networks              |               |
        |OAM        |                                      |               |
      +-----------+--------------------------------------+---------------+
        |IEEE       | Connectivity Fault Management        | IEEE 802.1ag  |
        |CFM        | [IEEE802.1ag]                        |               |
        |           |                                      |               |
        |           |  Note: CFM was originally published  |               |
        |           |  as IEEE 802.1ag, but is now         |               |
        |           |  incorporated in the 802.1Q standard.|               |
      +-----------+--------------------------------------+---------------+
        |IEEE       | Media Access Control Parameters,     | IEEE 802.3ah  |
        |802.3      | Physical Layers, and Management      |               |
        |link level | Parameters for Subscriber Access     |               |
        |OAM        | Networks [IEEE802.3ah]               |               |
        |           |                                      |               |

    Mizrahi, et al.         Expires July 9, 2013       [Page 11]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        |           |  Note: link level OAM was originally |               |
        |           |  defined in IEEE 802.3ah, and is now |               |
        |           |  incorporated 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

    Mizrahi, et al.         Expires July 9, 2013       [Page 12]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        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

TOM: Why is this section not at the top of this document, as is 
customary for RFCs?

    2.2. Terminology used in OAM Standards

    2.2.1. General Terms

        A wide variety of terms is used in various OAM standards. Each
    of the
        OAM standards listed in the reference section includes a section
    that
        defines terms relevant to that tool. A thesaurus of terminology for
        MPLS-TP terms is presented in [TP-Term], and provides a good summary
        of some of the OAM related terminology.

        This section presents a comparison of the terms used in various OAM
        standards, without fully quoting the definition of each term. For a
        formal definition of each term, refer to the references at the
    end 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 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 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).

    Mizrahi, et al.         Expires July 9, 2013       [Page 13]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        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]), as well as 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 that is equivalent to ME, but rather uses
        the term "session", referring to the relationship between two nodes
        using a BFD protocol. The MPLS LSP Ping ([LSP-Ping]) terminology
        simply uses the term "LSP" in this context.

        MPLS-TP has defined the terms ME and Maintenance Entity Group (MEG)
        in [TP-OAM-FW], similar to the terms defined by ITU-T.  A MEG allows
        the monitoring of a compound set of MEs, for example when monitoring
        a p2mp MEG that is considered to be the set of MEs between the root
        and each individual destination MEP.

    2.2.3. OAM Maintenance Points

        A Maintenance Point (MP) is a functional entity that is defined at a
        node in the network, and either initiates or reacts to OAM messages.
        A Maintenance End Point (MEP) is one of the end points of an ME, and
        can initiate OAM messages and respond to them. A Maintenance
        Intermediate Point (MIP) is an intermediate point between two MEPs,
        that does not generally initiate OAM frames (one exception to
    this is
        the use of AIS notifications), but is able to respond to OAM frames
        that are destined to it. A MIP in MPLS-TP identifies OAM packets
        destined to it by the value of 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, that is monitored by an OAM protocol
        either in the direction facing the network, or in the direction
        facing the bridge. A Down MP is an MP that receives OAM packets
    from,
        and transmits them to the direction of the network. An Up MP
    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 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.

    Mizrahi, et al.         Expires July 9, 2013       [Page 14]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    2.2.4. Proactive and On-demand activation

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

        o Proactive activation - indicates that the tool is activated on a
           continual basis periodically, where messages are sent between the
           two MEPs, and errors are detected when a certain number of
           expected messages are not received.

        o On-demand activation - indicates that the tool is activated
           "manually" to detect a specific anomaly.  In this activation a
           small number of OAM messages are sent by a MEP and the reply
           message is received.

    2.2.5. Connectivity Verification and Continuity Checks

        Two distinct classes of 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 in this document.

        Continuity checks are used to verify the liveness of a connection or
        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 to check
    whether it
        is connected to a peer MP or not. This function also allows the
    MP to
        verify that messages from the peer MP are received through the
        correct path, thereby verifying not only that the two MPs are
        connected, but also that they are connected through the expected
        path. This allows detection of unexpected topology changes. A
        connectivity verification (CV) protocol typically uses a CV message,
        followed by a CV reply that is sent back to 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 are used interchangeably in the
        standards, referring to a malfunction that can be detected by a
        connectivity or a continuity check. In some standards, such as
        [IEEE802.1ag], there is no distinction between these terms, while in

    Mizrahi, et al.         Expires July 9, 2013       [Page 15]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        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 in the normal operation, such as a consecutive
    period
        of time where no packets are delivered successfully. 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 Tools

    3.1. IP Ping and Traceroute

    3.1.1. Ping

        Ping is a common network diagnosis application for IP networks that
        uses ICMP. The ICMP Echo request/reply exchange is a connectivity
        verification function for the Internet Protocol. The originator
        transmits an ICMP Echo request packet, and the receiver replies with
        an Echo reply. ICMP ping is defined in two variants, [ICMPv4] is
    used
        for IPv4, and [ICMPv6] is used for IPv6.

    3.1.2. Traceroute

        Traceroute ([TCPIP-Tools], [NetTools]) is an application that allows
        users to discover the path between an IP source and an IP
        destination. Traceroute sends a sequence of UDP packets to UDP port
        33434 at the destination. By default, Traceroute begins by sending
        three packets (the number of packets is configurable in most
        Traceroute implementations), each with an IP Time-To-Live (TTL)
    value
        of one to the destination. These packets expire as soon as they
    reach
        the first router in the path. That router responds by sending three
        ICMP Time Exceeded Messages to the Traceroute application.
    Traceroute
        now sends another three UDP packets, each with the TTL value of 2.
        These messages cause the second router to return ICMP messages. This
        process continues, with ever increasing values for the TTL field,
        until the packets actually reach the destination. Because no
        application listens to port 33434 at the destination, the
    destination
        returns ICMP Destination Unreachable Messages indicating an
        unreachable port. This event indicates to the Traceroute application
        that it is finished.  The Traceroute program displays the round-trip
        delay associated with each of the attempts.

    Mizrahi, et al.         Expires July 9, 2013       [Page 16]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

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

        A few ICMP extensions ([ICMP-Ext], [ICMP-MP], [ICMP-Int]) have been
        defined in the context of Traceroute. These extensions augment the
        ICMP Destination Unreachable message, and can be used by Traceroute
        applications.

    3.2. Bidirectional Forwarding Detection (BFD)

    3.2.1. Overview

        While multiple OAM mechanisms have been defined for various
    protocols
        in the protocol stack, Bidirectional Forwarding Detection [BFD],
        defined by the IETF BFD working group, is a generic OAM mechanism
        that can be deployed over various encapsulating protocols, and in
        various medium types. The IETF has defined variants of the protocol
        for IP ([BFD-IP], [BFD-Multi]), for MPLS LSPs [BFD-LSP], and for
    PWE3
        [BFD-VCCV]. The usage of BFD in MPLS-TP is defined in [MPLS-TP-CC-
        CV].

        BFD includes two main OAM functions, using two types 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 are exchanged within a BFD session. BFD sessions
        operate in one of two modes:

        o Asynchronous mode (i.e. proactive): in this mode BFD control
           packets are sent periodically. When the receiver detects that no
           BFD control packet have been received during a predetermined
           period of time, a failure is detected.

        o Demand mode: 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 in each direction.

        Each of the end-points of the monitored path maintains its own
        session identification, called a Discriminator, both of which are
        included in the BFD Control Packets that are exchanged between the
        end-points.  At the time 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-

    Mizrahi, et al.         Expires July 9, 2013       [Page 17]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        points, based on information included in the control packets.  These
        transmission rates may be renegotiated during the session.

        During normal operation of the session, i.e. no failures are
        detected, the BFD session is in the Up state.  If no BFD Control
        packets are received during a fixed period of time, called the

TOM: Fixed, pre-configured or negotiated period of time (i.e.: BFD interval)

        Detection Time, the session is declared to be Down. The detection
        time is a function of the negotiated transmission time, and a
        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.

    3.2.3. BFD Echo

        A BFD echo packet is sent to a peer system, and is looped back
    to the
        originator. The echo function can be used proactively, or on-demand.

        The BFD echo function has been defined in BFD for IPv4 and IPv6
        ([BFD-IP]), but is not used in BFD for MPLS LSPs, PWs, or in BFD for
        MPLS-TP.

    3.3. 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 based on ICMP Ping and just like its predecessor may be
        used in one of two modes:

        o "Ping" mode: In this mode LSP ping is used for end-to-end
           connectivity verification between two LERs.

        o "Traceroute" mode: This mode is used for hop-by-hop fault
           isolation.

        LSP Ping extends the 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 also Maximum Transmission Unit (MTU) problems. The
        traceroute functionality may be used to isolate and localize the
    MPLS
        faults, using the Time-to-live (TTL) indicator to incrementally
        identify the sub-path of the LSP that is successfully traversed
        before the faulty link or node.

    Mizrahi, et al.         Expires July 9, 2013       [Page 18]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        It should be noted that LSP Ping supports unique identification of
        the LSP within an 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 Type-Length-Value (TLV) constructs. The usage of TLVs is
        typically not easy to perform in hardware, and is thus typically
        handled by the control plane.

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

    3.4. MPLS-TP OAM

    3.4.1. Overview

        The MPLS working group is currently working on defining the 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 behavior of the OAM
        mechanisms and a set of operations that should be supported by the
        OAM toolset.  The set of mechanisms required are further elaborated
        in [TP-OAM-FW], which describes the general architecture of the OAM
        system as well as giving overviews of the functionality of the OAM
        toolset.

        Some of the basic requirements for the 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 network is IP based, i.e. IP
    routing and
           forwarding are available, then the MPLS-TP OAM toolset should
    rely
           on the IP routing and forwarding capabilities. On the other hand,
           in environments where IP functionality is not available, the OAM
           tools must still be able to operate without dependence on IP
           forwarding and routing.

        o OAM packets and the user traffic are required to be congruent
           (i.e. OAM packets are transmitted in-band) and there is a need to
           differentiate OAM packets from user-plane ones. Inherent in this
           requirement is the principle that MPLS-TP OAM be independent of
           any existing control-plane, although it should not preclude
    use of
           the control-plane functionality.

    3.4.2. 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 [G-ACh] for LSP-based OAM traffic. This mechanism is
    based

    Mizrahi, et al.         Expires July 9, 2013       [Page 19]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        on the same concepts as the PWE3 ACH and VCCV mechanisms.  However,
        to address the needs of LSPs as differentiated from PW, the
    following
        concepts were defined for [G-ACh]:

        o An Associated Channel Header (ACH), that uses a format similar to
           the PW Control Word, is a 4-byte header that is prepended to OAM
           packets.

        o A Generic Associated Label (GAL). The GAL is a reserved MPLS label
           value (13) that indicates that the packet is an ACH packet
    and the
           payload follows immediately after the label stack.

    3.4.3. MPLS-TP OAM Toolset

        To address the functionality that is required of the OAM
    toolset, the
        MPLS WG conducted an analysis of the existing IETF and ITU-T OAM
        mechanisms and their ability to fulfill the required functionality.
        The conclusions of this analysis are documented in [OAM-Analys]. The
        MPLS working group currently plans to use a mixture of OAM
    mechanisms
        that are based on various existing standards, and adapt them to the
        requirements of [MPLS-TP-OAM]. Some of the main building blocks of
        this solution are based on:

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

        o LSP Ping 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 that are based on the
           functionality that is described in [ITU-T-Y1731].

        The following sub-sections describe the OAM tools defined for
    MPLS-TP
        as described 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 this 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 on-demand tool is defined in

    Mizrahi, et al.         Expires July 9, 2013       [Page 20]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        [OnDemand-CV].Proactively [MPLS-TP-OAM] states that the function
        should allow the MEPs to monitor the liveness and connectivity of a
        transport path. In on-demand mode, this function should support
        monitoring between the MEPs and, in addition, between a MEP and MIP.
        [TP-OAM-FW] highlights,  when performing Connectivity Verification,
        the need for the CC-V messages to include unique identification of
        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 3.2. ) with the additional limitation that the transmission
        and receiving rates are based on configuration by the operator.  The
        on-demand tool [OnDemand-CV] is an adaptation of LSP Ping (see
        Section 3.3. ) for the required behavior of MPLS-TP.

    3.4.3.2. Route Tracing

        [MPLS-TP-OAM] defines that there is a need for functionality that
        would allow a path end-point to identify the intermediate and end-
        points of the 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 3.3. ) functionality and is described in [OnDemand-CV].

    3.4.3.3. 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 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 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 is a function used by an intermediate point of a
        path, that becomes aware of a fault on the path, to report to the
        end-points of the path. [TP-OAM-FW] states that this may occur as a
        result of a defect condition discovered at a server sub-layer. This
        generates an Alarm Indication Signal (AIS) that continues until the

    Mizrahi, et al.         Expires July 9, 2013       [Page 21]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        fault is cleared. The consequent action of this 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 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 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 defined in [MPLS-TP-OAM] to allow
        the propagation information from one edge of the network to the
        other. The information concerns a defect to a client, in the case
        that the client does not support alarm notification.

    3.4.3.8. Packet Loss Measurement (LM)

        Packet Loss Measurement is a function used to verify the quality of
        the service. This function indicates the ratio of packets that are
        not delivered out of all packets that are transmitted by the path
        source.

        There are two possible ways of determining this measurement:

        o Using OAM packets, it is possible to compute the statistics based
           on a series of OAM packets. This, however, has the
    disadvantage of
           being artificial, and may not be representative since part of the
           packet loss may be dependent upon packet sizes.

TOM: Not just packet sizes. Things like implementation (as I mentioned 
above with the comment about the accuracy or truthfulness of the data 
plane processing of OAM packets).  Doing very accurate RTT as a simple 
example, with just IP Pings, is a tricky thing to make work.  Also, it 
is important to mention that the scale in terms of number of packets, 
number of tests, etc... can and will impact these parameters too.

        o Sending delimiting messages for the start and end of a measurement
           period during which the source and sink of the path count the
           packets transmitted and received. After the end delimiter, the
           ratio would be calculated by the path OAM entity.

    3.4.3.9. Packet Delay Measurement (DM)

        Packet Delay Measurement is a function that is used to measure one-
        way or two-way delay of a packet transmission between a pair of the
        end-points of a path (PW, LSP, or Section). Where:

    Mizrahi, et al.         Expires July 9, 2013       [Page 22]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        o One-way packet delay is the time elapsed from the start of
           transmission of the first bit of the packet by a source node
    until
           the reception of the last bit of that packet by the destination
           node.

        o Two-way packet delay is the time elapsed from the start of
           transmission of the first bit of the packet by a source node
    until
           the reception of the last bit of the loop-backed packet 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 of the two ways outlined above.

    3.5. PWE3 OAM

    3.5.1. PWE3 OAM using Virtual Circuit Connectivity Verification (VCCV)

        VCCV, as defined in [VCCV], provides a means for end-to-end fault
        detection and diagnostics tools to be extended 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 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 AC status. The use of the VCCV control channel provides
        the context, based on the MPLS-PW label, required to bind 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, 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 the responsibility of the operator to set consistent
        options at both ends.

TOM: Might be helpful to note that the static mode was created 
specifically to handle the MPLS-TP cases where no control plane was a 
requirement. However, new use cases such as pure mobile backhaul, etc... 
find this functionality useful too.

    Mizrahi, et al.         Expires July 9, 2013       [Page 23]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    3.5.2. PWE3 OAM using G-ACh

        As mentioned above, VCCV enables OAM for PWs by using 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 for
        PWs is defined in [PW-G-ACh].

    3.6. OWAMP and TWAMP

    3.6.1. 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].

        Alternative protocols for performance measurement are defined, 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 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 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 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

    Mizrahi, et al.         Expires July 9, 2013       [Page 24]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        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.

    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 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.

    Mizrahi, et al.         Expires July 9, 2013       [Page 25]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    3.6.4. 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.

      +-----------+-------+--------+--------+-----------+-------+--------+
        | Standard  |Continu|Connecti|Path    |Defect |Perform|Other   |
        |           |ity    |vity  |Discover|Indications|ance   |Function|
        |           |Check  |Verifica|y       | |Monitor|s       |
        |           |       |tion    |        | |ing    |        |
      +-----------+-------+--------+--------+-----------+-------+--------+
        |IP Ping    |       |Echo    |        |           |       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |IP         |       |        |Tracerou|           |       |        |
        |Traceroute |       |        |te      |           |       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |BFD        |BFD    |BFD     |        |           |       |        |
        |           |Control|Echo    |        |           |       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |MPLS OAM   |       |"Ping"  |"Tracero|           |       |        |
        |(LSP Ping) |       |mode    |ute"    |           |       |        |
        |           |       |        |mode    |           |       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |MPLS-TP    |CC     |CV/pro- |Route   |-Alarm |-LM    |-Diagnos|
        |OAM        |       |active  |Tracing | Reporting |-DM    | tic Tes|
        |           |       |or on-  |        |-Client    |       | t      |
        |           |       |demand  |        | Failure   |       |-Lock   |
        |           |       |        |        | Indication|       |        |
        |           |       |        |        |-Remote    |       |        |

    Mizrahi, et al.         Expires July 9, 2013       [Page 26]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        |           |       |        |        | Defect    |       |        |
        |           |       |        |        | Indication|       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |PWE3 OAM   |BFD    |-BFD    |LSP-Ping|           |       |        |
        |           |       |-ICMP   |        |           |       |        |
        |           |       | Ping   |        |           |       |        |
        |           |       |-LSP-   |        |           |       |        |
        |           |       | Ping   |        |           |       |        |
        + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
        |OWAMP and  |       |        |        | |-Delay |        |
        |TWAMP      |       |        |        |           | measur|        |
        |           |       |        |        |           | ement |        |
        |           |       |        |        | |-Packet|        |
        |           |       |        |        |           | loss  |        |
        |           |       |        |        |           | measur|        |
        |           |       |        |        |           | 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.

    Mizrahi, et al.         Expires July 9, 2013       [Page 27]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

    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 and Management
                      (OAM)", RFC 4378, February 2006.

        [OAM-Label]   Ohta, H., "Assignment of the '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 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): 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,
                      RFC 792, September 1981.

        [ICMPv6]      Conta, A., Deering, S., and M. Gupta, "Internet
    Control
                      Message Protocol (ICMPv6) 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.

    Mizrahi, et al.         Expires July 9, 2013       [Page 28]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        [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 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]    Stine, R., "FYI on a Network Management Tool Catalog:
                      Tools for Monitoring and Debugging TCP/IP Internets
                      and Interconnected Devices", RFC 1147, April 1990.

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

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

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

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

        [IPPM-2DM]    Almes, G., Kalidindi, S., Zekauskas, M., "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)", RFC 4656, September 2006.

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

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

    Mizrahi, et al.         Expires July 9, 2013       [Page 29]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        [BFD-IP]      Katz, D., Ward, D., "Bidirectional Forwarding
    Detection
                      (BFD) for IPv4 and 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 Pseudowire Virtual Circuit
                      Connectivity Verification (VCCV)", RFC 5885, June
                      2010.

        [TP-OAM-FW]   Busi, I., Allan, D., "Operations, Administration and
                      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 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 for MPLS Networks", RFC 6374, September
                      2011.

        [TP-LM-DM]    Frost, D., Bryant, S., "A Packet Loss and 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
                      Maintenance (OAM)", RFC 6427, November 2011.

    Mizrahi, et al.         Expires July 9, 2013       [Page 30]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        [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 Generic Associated Channel
                      Type for ITU-T MPLS 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 of the OAM
                      acronym in the IETF ", RFC 6291, June 2011.

        [OAM-Analys]  Sprecher, N., Fang, L., "An Overview of the 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 and ITU-T's Transport Network
                      Recommendations", work-in-progress, draft-ietf-mpls-
                      tp-rosetta-stone, July 2012.

        [IEEE802.1ag] IEEE 802.1Q, "IEEE Standard for Local and metropolitan
                      area networks - 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 and
                      Mechanisms for Ethernet-based Networks", July 2011.

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

    Mizrahi, et al.         Expires July 9, 2013       [Page 31]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        [IEEE802.3ah] 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 and 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.

    Authors' Addresses

        Tal Mizrahi
        Marvell
        6 Hamada St.
        Yokneam, 20692
        Israel

        Email: [email-masked]

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

        Email: [email-masked]

        Elisa Bellagamba
        Ericsson
        6 Farogatan St.
        Stockholm,   164 40
        Sweden

    Mizrahi, et al.         Expires July 9, 2013       [Page 32]
    Internet-Draft       Overview of OAM Mechanisms   January 2013

        Phone: +46 761440785
        Email: [email-masked]

        Yaacov Weingarten
        34 Hagefen St.
        Karnei Shomron,   4485500
        Israel

        Email: [email-masked]

---

From: "Romascanu, Dan (Dan)" <[email-masked]>
Date: Thu, 24 Jan 2013 16:23:04 +0000

This is a useful and well-written document and I support its publication. I have a few comments which I would be glad if they were addressed: 

1. I believe that the document must include reference to TRILL OAM, referencing draft-ietf-trill-oam-req-04 (which is close to approval) and including a section on TRILL OAM in the table in 1.4. 

2. The reference to Non-IETF documents in section 1.5 should mention the fact that non-IETF documents deal in many cases with OAM functions below the IP layer (layer 2, "2.5") and that operators use in some cases a multi-layered OAM approach function of the way their networks are architectured.

3. Section 1.5 mentions [IEEE802.1ag] under 'OAM mechanisms for Ethernet based networks'. In reality CFM as defined by IEEE 802.1ag is designed to apply for all bridged networks in IEEE 802, whatever the media protocol is being used. 

4. Together with .1ag I would recommend to also include in the table and list of references the CFM extensions defined in 802.1Qaw - Management of data-driven and data-dependent connectivity faults 

5. I am a little concerned of this document defining - once more - in sections 3.4.3.8 and 3.4.3.9 metrics and speak about measurement methods for Packet Loss and Packet Delay. I would prefer to refer to IPPM RFCs for this purpose

6. Section 1.1 mentions delay variation when describing the Delay Measurement (DM) function, but section 3.4.3.9 'forgets' it. I believe that delay variation is important and needs to be covered. 

Regards,

Dan

> -----Original Message-----
> From: [email-masked] [mailto:ietf-announce-
> [email-masked]] On Behalf Of The IESG
> Sent: Friday, January 11, 2013 9:36 PM
> To: IETF-Announce
> Cc: [email-masked]
> Subject: Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An Overview
> of Operations, Administration, and Maintenance (OAM) Mechanisms) to
> Informational RFC
> 
> 
> [email-masked] mailing lists by 2013-01-25. Exceptionally, comments may
> be sent to [email-masked] instead. In either case, please retain the

---

From: Sam Aldrin <[email-masked]>
Date: Tue, 15 Jan 2013 10:59:07 -0800

Here are my comments.

#1

   An OAM protocol is run in the context of a Maintenance Domain,
   consisting of two or more nodes that run the OAM protocol, referred
   to as Maintenance Points (MP).
%sam - I do not think that, MP, MEP, etc.,  terminology is used in OAM across different layers. It was introduced in MPLS-TP and later in TRILL, but prior to that, it is not. Is it the authors intention that this new terminology be used going forward?

#2
Sec 1.1 - An OAM protocol typically supports one or more of the
   tools described below.
%sam - what is OAM protocol? Shouldn't it be management plane OR OAM tools?

#3 
Section 1.2 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 that are used for OAM.
%sam - Why is it out of scope? For example, checking consistency of control plane to forwarding plane is part of OAM or not? 

#4
Section 1.3 The set of OAM
   mechanisms described in this memo are applicable to IP unicast, MPLS,
   pseudowires, and MPLS for the transport environment (MPLS-TP).
%sam - For ex: Is ATM OAM (RFC4717) within the scope of this draft? I did't see any mention of it or FR. I know that they are legacy, but still within IETF. One day even MPLS will be legacy protocol (just saying :D)

#5
Over all draft
%sam - I do not think this draft even considered 'multicast traffic'. There are rfc's in ever layer supporting multicast. There is no reference I could find. Ex: RFC6450, RFC6425 etc

#6
Sec 3.5 
%sam - I think it is good to add details on different types of VCCV types of CC and CV and their use. 

#7
General
%sam - Do you consider MIB part of OAM? Does Traps considered as error reporting or fault indication?

#8 
Sec 3.4.3.8 and 9
%sam - Do these consider actual packet LM and DM or synthetic packets? 

#9 
Section 4
%sam - I think this section should provide more details on what the general security issues are with OAM messages etc. And how they could be mitigated. For in-depth details, one could go into each of those documents.

#10
Sec 3.7
I do not think this is complete representation. For ex: no representation of multicast. BFD could be used for RDI, I think. 

#11
IP Ping and Traceroute
%sam - When you say IP ping, does it imply ICMP ping or IP/UDP ping?

cheers
-sam
On Jan 15, 2013, at 6:48 AM, Benoit Claise <[email-masked]> wrote:

>     because no such tool is cited in the memo (and the term “throughput”
>> Is this document in line with http://tools.ietf.org/html/draft-ietf-trill-oam-req-04? 
>> If speak about OWAMP or TWAMP 'synthetic traffic), is that data plane, control plane, or management plane?
>> Interestingly enough, after reading the document, I reviewed http://datatracker.ietf.org/doc/draft-ietf-opsawg-oam-overview/ballot/, and saw the same feedback from Stewart Bryant:
>> to various “planes” of networking (data plane, control plane,
>> Just one example with section 3.2.2
>> -
>> When we did RFC 6632, which is the companion document, we had http://tools.ietf.org/html/rfc6632#section-1.1
>>