Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An Overview of Operations, Administration, and Maintenance (OAM) Mechanisms) to Informational RFC
Benoit Claise <bclaise@cisco.com> Tue, 18 February 2014 11:13 UTC
Return-Path: <bclaise@cisco.com>
X-Original-To: opsawg@ietfa.amsl.com
Delivered-To: opsawg@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2A3011A03D0 for <opsawg@ietfa.amsl.com>; Tue, 18 Feb 2014 03:13:12 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: 3.964
X-Spam-Level: ***
X-Spam-Status: No, score=3.964 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, FH_RELAY_NODNS=1.451, HELO_MISMATCH_COM=0.553, HTML_MESSAGE=0.001, HTML_TAG_BALANCE_BODY=1.157, J_CHICKENPOX_24=0.6, J_CHICKENPOX_34=0.6, J_CHICKENPOX_84=0.6, RDNS_NONE=0.793, SPF_PASS=-0.001, T_DKIM_INVALID=0.01] autolearn=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id d1ahHDFYCpgz for <opsawg@ietfa.amsl.com>; Tue, 18 Feb 2014 03:12:57 -0800 (PST)
Received: from aer-iport-4.cisco.com (unknown [173.38.203.54]) by ietfa.amsl.com (Postfix) with ESMTP id 2E9AF1A047C for <opsawg@ietf.org>; Tue, 18 Feb 2014 03:12:51 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=602244; q=dns/txt; s=iport; t=1392721968; x=1393931568; h=message-id:date:from:mime-version:to:cc:subject: references:in-reply-to; bh=HN17TtbY2sHuGpumso5At/J167+zLjbILHeUCQuomtU=; b=LhWQkCyDzppdIfF1QmZl3OGzIfXKhbffwBCAgRufB3wfvLcD1lvOcK8w Qr4zBO6LX2E/eRRfuVcH0nEOKz4EBJ+QpSKurvGot95zaY/uXzpBFHVdi FKCiri3AcVNY7xlmaJ6DOUaPtuEYQwmC8ZzpCEbzuPsAuJYXOsHle7HOv A=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: ApsEAL0/A1OQ/khL/2dsb2JhbADFag
X-IronPort-AV: E=Sophos;i="4.97,501,1389744000"; d="scan'208,217";a="630160"
Received: from ams-core-2.cisco.com ([144.254.72.75]) by aer-iport-4.cisco.com with ESMTP; 18 Feb 2014 11:12:44 +0000
Received: from [10.60.67.85] (ams-bclaise-8914.cisco.com [10.60.67.85]) by ams-core-2.cisco.com (8.14.5/8.14.5) with ESMTP id s1IBCeWm003676; Tue, 18 Feb 2014 11:12:40 GMT
Message-ID: <53034028.1080006@cisco.com>
Date: Tue, 18 Feb 2014 12:12:40 +0100
From: Benoit Claise <bclaise@cisco.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
MIME-Version: 1.0
To: Tal Mizrahi <talmi@marvell.com>, Thomas Nadeau <tnadeau@lucidvision.com>
References: <20130111193616.19158.16205.idtracker@ietfa.amsl.com> <50F437BF.8040005@cisco.com> <50F972FC.2030707@cisco.com> <6C3490D7-3727-41BA-8980-683DF84451A2@lucidvision.com> <74470498B659FA4687F0B0018C19A89C01D43919C122@IL-MB01.marvell.com> <35CAD982-D991-4BED-8F19-3CDFDADE1EB7@lucidvision.com> <74470498B659FA4687F0B0018C19A89C01D43919C2A4@IL-MB01.marvell.com>
In-Reply-To: <74470498B659FA4687F0B0018C19A89C01D43919C2A4@IL-MB01.marvell.com>
Content-Type: multipart/alternative; boundary="------------000401030308050104080508"
Archived-At: http://mailarchive.ietf.org/arch/msg/opsawg/pL_bAl6gSLYW2xlcz2gvHwmOd7s
Cc: "draft-ietf-opsawg-oam-overview@tools.ietf.org" <draft-ietf-opsawg-oam-overview@tools.ietf.org>, "opsawg@ietf.org" <opsawg@ietf.org>, "opsawg-chairs@tools.ietf.org" <opsawg-chairs@tools.ietf.org>
Subject: Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An Overview of Operations, Administration, and Maintenance (OAM) Mechanisms) to Informational RFC
X-BeenThere: opsawg@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: OPSA Working Group Mail List <opsawg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/opsawg>, <mailto:opsawg-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/opsawg/>
List-Post: <mailto:opsawg@ietf.org>
List-Help: <mailto:opsawg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/opsawg>, <mailto:opsawg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 18 Feb 2014 11:13:12 -0000
Hi Tal, AFAICT, this issue below is the only one left on the draft. The draft improved much, thanks. Please post a new version with the change, and I'll put it on the IESG table. Regards, Benoit > > Hi Tom, > > Thanks for the prompt response. > > We will apply this change in the next draft. > > Thanks, > > Tal. > > *From:*Thomas Nadeau [mailto:tnadeau@lucidvision.com] > *Sent:* Tuesday, January 28, 2014 5:38 PM > *To:* Tal Mizrahi > *Cc:* draft-ietf-opsawg-oam-overview@tools.ietf.org; opsawg@ietf.org; > opsawg-chairs@tools.ietf.org; Benoit Claise; joel jaeggli > (joelja@bogus.com); Scott O. Bradner (sob@harvard.edu) > *Subject:* Re: Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An > Overview of Operations, Administration, and Maintenance (OAM) > Mechanisms) to Informational RFC > > The changes look ok except for one minor one: > > One of the changes in 4.4.2 BFD for MPLS states the following: > > The advantage of BFD is that it can > > > > > > > > > > provide faster failure detection, and scales better to a large number > > > > > > > > > > of LSPs > > > > That is a popular misconception. When I at a previous gig we were able > to actually figure out how to make them both perform > > equally well for CV operations, but we just decided to not implement > it that way. I'd suggest removing that sentence altogether. > > They are two tools with different implementations, some more optimal > than others. > > Hi Tom, > > Thanks again for your comments. > > A link to the updated draft: > > http://tools.ietf.org/html/draft-ietf-opsawg-oam-overview-13 > > We believe the current draft addresses all the comments below. > > We have replied to every single comment below (search for [TM]). > > Please let us know if you believe something is still amiss. > > Thanks, > > Tal. > > *From:*Thomas Nadeau [mailto:tnadeau@lucidvision.com] > *Sent:* Monday, January 20, 2014 5:29 PM > *To:* Benoit Claise > *Cc:* draft-ietf-opsawg-oam-overview@tools.ietf.org > <mailto:draft-ietf-opsawg-oam-overview@tools.ietf.org>; > opsawg@ietf.org <mailto:opsawg@ietf.org>; IETF Disgust > *Subject:* Re: Last Call: <draft-ietf-opsawg-oam-overview-08.txt> > (An Overview of Operations, Administration, and Maintenance (OAM) > Mechanisms) to Informational RFC > > Reviewing the current version of the draft (12), many of the > comments below are still not addressed. > > --Tom > > 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. > > */[TM] The current draft includes a significantly clearer > explanation, up front in the abstract and introduction, that > this document focuses on OAM tools, i.e., on the data plane of > OAM. That is why, for example we do not discuss configuration > contexts such as CCAMP./* > > 2. There is no real discussion around the security aspects of > these tools. Should there be? > > *//* > > */[TM] We received a similar comment from other reviewers, as > well as the SecDir review in the previous IETF last call. > After some discussion between our AD at the time (Ron Bonica) > and the Sec AD (Sean Turner), the current phrasing of the > "Security Considerations" section was agreed. It is mainly an > issue of where you draw the line between which content to > include and which content not to include in the draft, and > security is currently out of scope. /* > > 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. > > *//* > > */[TM] Following your comment, we added quite a bit of text to > the introduction to explain this multi-layer orchestration. > You can take full credit for the fact that this doll IETF > draft now includes an ASCII art figure (Figure 1). :)/* > > 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. > > */[TM] Following your comment we added a note about this in > section 4.7.1. See the paragraphs beginning with "It should be > noted that while [OWAMP]..."./* > > 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 > > 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. > > 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. > > */[TM] We significantly improved the distinction between the > different planes: data plane, control plane, management plane. > We added a definition of each of the terms, and we now > explicitly explain that the draft focuses on the data plane. > We also explain in the current draft that we adopt the OAM > acronym as recommended in RFC 6291: Operations, Administration > and Maintenance (without Management...). Please let us know if > you think something is still missing here./* > > 1.1. The Building Blocks of OAM > > 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. > > */[TM] We rephrased this paragraph, and hopefully it is > clearer and more accurate now./* > > 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. > > 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. > > */[TM] True. However this section presents a short list of > typical OAM functions, and we would rather stick with succinct > descriptions in this section. /* > > 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. > > */[TM] We rephrased this subsection, and now have a much > clearer definition of each plane in "2.2.4. Data Plane, > Control Plane and Management Plane". We also added specific > text about the importance of fate-sharing (see section 1.4), > which addresses the second part of your comment./* > > 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. > > */[TM] Removed./* > > 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 > > Table 1 summarizes the IETF OAM related RFCs discussed > in this > > document. > > 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? > > */[TM] The introduction is now significantly shorter than it > was when you sent this comment, which means that the > terminology section is now much closer to the beginning of the > document./* > > 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) > > */[TM] We rephrased this sentence./* > > 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. > > */[TM] Following your comment we rephrased this sentence./* > > 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. > > */[TM] Following your comment we added some text to explain > this./* > > 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. > > 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 | | > > +-----------+-------+--------+--------+-----------+-------+--------+ > > |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: talmi@marvell.com <mailto:talmi@marvell.com> > > Nurit Sprecher > > Nokia Siemens Networks > > 3 Hanagar St. Neve Ne'eman B > > Hod Hasharon, 45241 > > Israel > > Email: nurit.sprecher@nsn.com > <mailto:nurit.sprecher@nsn.com> > > 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: elisa.bellagamba@ericsson.com > <mailto:elisa.bellagamba@ericsson.com> > > Yaacov Weingarten > > 34 Hagefen St. > > Karnei Shomron, 4485500 > > Israel > > Email: wyaacov@gmail.com <mailto:wyaacov@gmail.com> > > 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 > > > > 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. > > > > 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 > > > > 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 > > ietf@ietf.org <mailto:ietf@ietf.org> mailing lists by 2013-01-25. Exceptionally, comments may be > > sent toiesg@ietf.org <mailto:iesg@ietf.org> 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. > > > > > > >
- [OPSAWG] Last Call: <draft-ietf-opsawg-oam-overvi… The IESG
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Benoit Claise
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Benoit Claise
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Benoit Claise
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Romascanu, Dan (Dan)
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Sam Aldrin
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Thomas Narten
- [OPSAWG] FW: Re: Last Call: <draft-ietf-opsawg-oa… MORTON, ALFRED C (AL)
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Thomas Nadeau
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Tal Mizrahi
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Tal Mizrahi
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Thomas Nadeau
- Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-ov… Benoit Claise