draft-ietf-opsawg-oam-overview-05.txt   draft-ietf-opsawg-oam-overview-06.txt 
Operations and Management Area Working Group T. Mizrahi Operations and Management Area Working Group T. Mizrahi
Internet Draft Marvell Internet Draft Marvell
Intended status: Informational N. Sprecher Intended status: Informational N. Sprecher
Expires: November 2011 Nokia Siemens Networks Expires: September 2012 Nokia Siemens Networks
E. Bellagamba E. Bellagamba
Ericsson Ericsson
Y. Weingarten Y. Weingarten
Nokia Siemens Networks Nokia Siemens Networks
May 16, 2011 March 12, 2012
An Overview of An Overview of
Operations, Administration, and Maintenance (OAM) Mechanisms Operations, Administration, and Maintenance (OAM) Mechanisms
draft-ietf-opsawg-oam-overview-05.txt draft-ietf-opsawg-oam-overview-06.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 Status of this Memo
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Abstract
Operations, Administration, and Maintenance (OAM) is a general term
that refers to a toolset that can be used for fault detection and
localization, 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, as well as
a comparison to other OAM mechanisms that have been defined by the
IEEE and ITU-T.
Table of Contents Table of Contents
1. Introduction................................................4 1. Introduction ................................................. 3
2. Conventions used in this document............................8 1.1. Background .............................................. 3
3. Basic Terminology...........................................8 1.2. The OAM toolsets ........................................ 4
3.1. Abbreviations..........................................8 1.3. IETF OAM Standards ...................................... 5
3.2. Terminology used in OAM Standards.......................9 1.4. Non-IETF OAM Standards .................................. 8
3.2.1. General Terms......................................9 2. Basic Terminology ............................................ 9
3.2.2. OAM Maintenance Entities and Communication Links...10 2.1. Abbreviations ........................................... 9
3.2.3. OAM Maintenance Points............................10 2.2. Terminology used in OAM Standards ...................... 10
3.2.4. Connectivity Verification and Continuity Checks....11 2.2.1. General Terms ..................................... 10
3.2.5. Link Failures.....................................11 2.2.2. OAM Maintenance Entities .......................... 11
3.2.6. Summary of OAM Terms used in the Standards.........12 2.2.3. OAM Maintenance Points ............................ 11
4. OAM Functions..............................................13 2.2.4. Proactive and On-demand activation ................ 12
4.1. ICMP Ping.............................................13 2.2.5. Connectivity Verification and Continuity Checks ... 12
4.2. Bidirectional Forwarding Detection (BFD)...............14 2.2.6. Failures .......................................... 13
4.2.1. Overview.........................................14 3. OAM Tools ................................................... 13
4.2.2. BFD Control.......................................14 3.1. ICMP Ping .............................................. 13
4.2.3. BFD Echo.........................................15 3.2. Traceroute ............................................. 13
4.3. LSP Ping..............................................15 3.3. Bidirectional Forwarding Detection (BFD) ............... 14
4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV)...16 3.3.1. Overview .......................................... 14
4.5. IP Performance Metrics (IPPM)..........................16 3.3.2. BFD Control ....................................... 14
4.5.1. Overview.........................................16 3.3.3. BFD Echo .......................................... 15
4.5.2. Control and Test Protocols........................17 3.4. LSP Ping ............................................... 15
4.5.3. OWAMP............................................17 3.5. PWE3 Virtual Circuit Connectivity Verification (VCCV) .. 16
4.5.4. TWAMP............................................18 3.6. IP Performance Metrics (IPPM) .......................... 17
4.6. ITU-T Y.1711..........................................18 3.6.1. Overview .......................................... 17
4.6.1. Overview.........................................18 3.6.2. Control and Test Protocols ........................ 17
4.6.2. Connectivity Verification (CV)....................19 3.6.3. OWAMP ............................................. 18
4.6.3. Fast Failure Detection (FFD)......................19 3.6.4. TWAMP ............................................. 18
4.6.4. Forward Defect Indication (FDI)...................19 3.7. MPLS-TP OAM ............................................ 19
4.6.5. Backward Defect Indication (BDI)..................20 3.7.1. Overview .......................................... 19
4.7. ITU-T Y.1731..........................................20 3.7.2. Generic Associated Channel ........................ 19
4.7.1. Overview.........................................20 3.7.3. MPLS-TP OAM Toolset ............................... 20
4.7.2. ETH-CC...........................................20 3.7.3.1. Continuity Check and Connectivity Verification 20
4.7.3. ETH-LB...........................................21 3.7.3.2. Route Tracing ................................ 21
4.7.4. ETH-TST..........................................21 3.7.3.3. Lock Instruct ................................ 21
4.7.5. ETH-LT...........................................21 3.7.3.4. Lock Reporting ............................... 21
4.7.6. ETH-AIS..........................................21 3.7.3.5. Alarm Reporting .............................. 21
4.7.7. ETH-LCK..........................................21 3.7.3.6. Remote Defect Indication ..................... 22
4.7.8. ETH-RDI..........................................22 3.7.3.7. Client Failure Indication .................... 22
4.7.9. ETH-APS..........................................22 3.7.3.8. Packet Loss Measurement ...................... 22
4.7.10. ETH-LM..........................................22 3.7.3.9. Packet Delay Measurement ..................... 22
4.7.11. ETH-DM..........................................22 3.8. Summary of OAM Functions ............................... 23
4.8. IEEE 802.1ag..........................................23 4. Security Considerations ..................................... 24
4.8.1. Overview.........................................23 5. IANA Considerations ......................................... 24
4.8.2. Continuity Check..................................23 6. Acknowledgments ............................................. 24
4.8.3. Loopback.........................................23 7. References .................................................. 24
4.8.4. Linktrace........................................24 7.1. Normative References ................................... 24
4.9. IEEE 802.3ah..........................................24 7.2. Informative References ................................. 27
4.9.1. Overview.........................................24
4.9.2. Remote Failure Indication.........................24
4.9.3. Remote Loopback...................................24
4.9.4. Link Monitoring...................................24
4.10. MPLS-TP OAM..........................................24
4.10.1. Overview........................................24
4.10.2. Generic Associated Channel.......................25
4.10.3. MPLS-TP OAM Toolset..............................25
4.10.3.1. Continuity Check and Connectivity Verification26
4.10.3.2. Diagnostic Tests............................26
4.10.3.3. Route Tracing...............................26
4.10.3.4. Lock Instruct...............................27
4.10.3.5. Lock Reporting..............................27
4.10.3.6. Alarm Reporting.............................27
4.10.3.7. Remote Defect Indication....................27
4.10.3.8. Client Failure Indication...................27
4.10.3.9. Packet Loss Measurement.....................27
4.10.3.10. Packet Delay Measurement...................28
4.11. Summary of OAM Functions..............................28
4.12. Summary of Continuity Check Mechanisms................30
5. Security Considerations.....................................31
6. IANA Considerations........................................31
7. Acknowledgments............................................31
8. References.................................................31
8.1. Normative References...................................31
8.2. Informative References.................................33
1. Introduction 1. Introduction
OAM is a general term that refers to a toolset that can be used for OAM is a general term that refers to a toolset that can be used for
detecting, isolating and reporting connection failures or measurement detecting, isolating and reporting connection failures or measurement
of connection performance parameters. The term OAM has been used over of connection performance parameters. The term OAM has been used over
the years in several different contexts, as discussed in [OAM Soup]. the years in several different contexts, as discussed in [OAM Def].
In the context of this document OAM refers to Operations, This term as been associated with the 3 logical abstraction layers:
Administration, and Maintenance, i.e., this document refers to OAM in the forwarding plane, the control plane, and the management plane. In
the context of monitoring communication entities, e.g., nodes, paths, the context of this document OAM refers to Operations,
physical links, or logical links. Other aspects associated with the Administration, and Maintenance. Hence, management aspects are
OAM acronym, such as management, are outside the scope of this outside the scope of this document.
document.
OAM was originally used in the world of telephony, and has been 1.1. Background
adopted in packet based networks. OAM mechanisms are used in various
layers in the protocol stack, and are applied to a variety of
different protocols.
The IETF has defined OAM for several protocols, and is currently The communication of a network may be configured and maintained by
working on defining several new OAM protocols. A summary of these use of various tools at different layers - these include use of a
protocols, old and new, is listed below: control plane or management plane to configure and maintain the
connectivity of the network from the outside - looking in - and
controlling the connections when the need arises. OAM, on the other
hand, traditionally has been used to maintain the connectivity in-
band with the actual data traffic, i.e. in the data plane.
o MPLS LSP Ping, as defined in [LSP Ping] is an OAM mechanism for While the OAM tools may, and quite often do, work in conjunction with
point to point MPLS LSPs. The IETF is currently working on an a control-plane or management plane, they are usually defined to be
extension to the LSP Ping for point to multipoint MPLS - [P2MP independent of the control-plane. The OAM tools communicate with the
Ping]. management plane to raise alarms, and often the on-demand tools may
be activated by the management, e.g. to locate and localize problems.
o Virtual Circuit Connectivity Check (VCCV) for Pseudowires, as The considerations of the control-plane maintenance tools or the
defined in [VCCV]. functionality of the management-plane are out of scope for this
document, which will concentrate on presenting the data-plane tools
that are used for OAM.
o ICMP Echo request, also known as Ping, as defined in [ICMPv4], and 1.2. 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
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 ICMP Ping:
ICMP Echo request, also known as Ping, as defined in [ICMPv4], and
[ICMPv6]. ICMP Ping is a very simple and basic mechanism in [ICMPv6]. ICMP Ping is a very simple and basic mechanism in
failure diagnosis, and is not traditionally associated with OAM, failure diagnosis. LSP Ping is to some extent based on ICMP Ping.
but it is presented in this document for the sake of completeness,
since both LSP Ping and VCCV are to some extent based on ICMP
Ping.
o Bidirectional Forwarding Detection (BFD) is defined in [BFD] as a o IPPM:
IP Performance Metrics (IPPM) is a working group in the IETF that
defined common metrics for performance measurement, as well as a
protocol for measuring delay and packet loss in IP networks.
o MPLS:
MPLS LSP Ping, as defined in [MPLS OAM], [MPLS OAM FW] and [LSP
Ping], is an OAM mechanism for point to point MPLS LSPs.
o MPLS-TP:
The OAM requirements for MPLS Transport Profile (MPLS-TP) are
defined in [MPLS-TP OAM], and the toolset is described in [TP OAM
FW].
o BFD:
Bidirectional Forwarding Detection (BFD) is defined in [BFD] as a
framework for a lightweight generic OAM mechanism. The intention framework for a lightweight generic OAM mechanism. The intention
is to define a base mechanism that can be used with various is to define a base mechanism that can be used with various
encapsulation types, network environments, and in various medium encapsulation types, network environments, and in various medium
types. types.
o The OAM requirements for MPLS Transport Profile (MPLS-TP) are This document summarizes the OAM mechanisms defined by the IETF. We
defined in [MPLS-TP OAM], and the toolset is described in [MPLS-TP first present a comparison of the terminology used in various OAM
OAM FW]. The OAM toolset for MPLS-TP is currently being defined in standards, and then summarize the OAM functions that each OAM
the MPLS working group. standard provides.
o IP Performance Metrics (IPPM) is a working group in the IETF that 1.3. IETF OAM Standards
defined common metrics for performance measurement, as well as a
protocol for measuring delay and packet loss in IP networks. Table 1 summarizes the IETF OAM standards discussed in this document.
Alternative protocols for performance measurement are defined, for
example, in MPLS-TP OAM [MPLS-TP OAM], and in Ethernet OAM [ITU-T The table includes a "Type" column, specifying the nature of each of
Y.1731]. 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 |
+-----------+--------------------------------------+-----+----------+
|ICMPv4 Ping| Internet Control Message Protocol |Tool | RFC 792 |
| | | | |
+-----------+--------------------------------------+-----+----------+
|ICMPv6 Ping| Internet Control Message Protocol |Tool | RFC 4443 |
| | (ICMPv6) for the Internet Protocol | | |
| | Version 6 (IPv6) Specification | | |
+-----------+--------------------------------------+-----+----------+
|Traceroute | A Primer On Internet and TCP/IP |Tool | RFC 2151 |
| | Tools and Utilities | | |
+-----------+--------------------------------------+-----+----------+
|BFD | Bidirectional Forwarding Detection |Tool | RFC 5880 |
| +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5881 |
| | (BFD) for IPv4 and IPv6 (Single Hop) | | |
| +--------------------------------------+-----+----------+
| | Generic Application of Bidirectional |Misc.| RFC 5882 |
| | Forwarding Detection | | |
| +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5883 |
| | (BFD) for Multihop Paths | | |
| +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5884 |
| | for MPLS Label Switched Paths (LSPs) | | |
| +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5885 |
| | for the Pseudowire Virtual Circuit | | |
| | Connectivity Verification (VCCV) | | |
+-----------+--------------------------------------+-----+----------+
|IETF MPLS | Operations and Management (OAM) |Misc.| RFC 4377 |
|OAM | Requirements for Multi-Protocol Label| | |
|(LSP Ping) | Switched (MPLS) Networks | | |
| +--------------------------------------+-----+----------+
| | A Framework for Multi-Protocol |Misc.| RFC 4378 |
| | Label Switching (MPLS) Operations | | |
| | and Management (OAM) | | |
| +--------------------------------------+-----+----------+
| | Detecting Multi-Protocol Label |Tool | RFC 4379 |
| | Switched (MPLS) Data Plane Failures | | |
| +--------------------------------------+-----+----------+
| | Operations and Management (OAM) |Misc.| RFC 4687 |
| | Requirements for Point-to-Multipoint | | |
| | MPLS Networks | | |
| +--------------------------------------+-----+----------+
| | ICMP Extensions for Multiprotocol |Tool | RFC 4950 |
| | Label Switching | | |
+-----------+--------------------------------------+-----+----------+
|MPLS-TP | Requirements for OAM in MPLS-TP |Misc.| RFC 5860 |
|OAM +--------------------------------------+-----+----------+
| | MPLS Generic Associated Channel |Inf. | RFC 5586 |
| +--------------------------------------+-----+----------+
| | MPLS-TP OAM Framework |Misc.| RFC 6371 |
| +--------------------------------------+-----+----------+
| | Proactive Connectivity Verification, |Tool | RFC 6428 |
| | Continuity Check, and Remote Defect | | |
| | Indication for the MPLS Transport | | |
| | Profile | | |
| +--------------------------------------+-----+----------+
| | MPLS On-Demand Connectivity |Tool | RFC 6426 |
| | Verification and Route Tracing | | |
| +--------------------------------------+-----+----------+
| | MPLS Fault Management Operations, |Tool | RFC 6427 |
| | Administration, and Maintenance (OAM)| | |
| +--------------------------------------+-----+----------+
| | MPLS Transport Profile Lock Instruct |Tool | RFC 6435 |
| | and Loopback Functions | | |
| +--------------------------------------+-----+----------+
| | Packet Loss and Delay Measurement for|Tool | RFC 6374 |
| | MPLS Networks | | |
| +--------------------------------------+-----+----------+
| | A Packet Loss and Delay Measurement |Prof.| RFC 6375 |
| | Profile for MPLS-Based Transport | | |
| | Networks | | |
+-----------+--------------------------------------+-----+----------+
|PW VCCV | Pseudowire Virtual Circuit |Inf. | RFC 5085 |
| | Connectivity Verification (VCCV): | | |
| | A Control Channel for Pseudowires | | |
+-----------+--------------------------------------+-----+----------+
|IPPM | Framework for IP Performance Metrics |Misc.| RFC 2330 |
| +--------------------------------------+-----+----------+
| | IPPM Metrics for Measuring |Misc.| RFC 2678 |
| | Connectivity | | |
| +--------------------------------------+-----+----------+
| | A One-way Delay Metric for IPPM |Misc.| RFC 2679 |
| +--------------------------------------+-----+----------+
| | A One-way Packet Loss Metric for IPPM|Misc.| RFC 2680 |
| +--------------------------------------+-----+----------+
| | A Round-trip Delay Metric for IPPM |Misc.| RFC 2681 |
| +--------------------------------------+-----+----------+
| | A One-way Active Measurement Protocol|Tool | RFC 4656 |
| | (OWAMP) | | |
| +--------------------------------------+-----+----------+
| | A Two-Way Active Measurement Protocol|Tool | RFC 5357 |
| | (TWAMP) | | |
+-----------+--------------------------------------+-----+----------+
Table 1 Summary of IETF OAM Related Standards
1.4. Non-IETF OAM Standards
In addition to the OAM mechanisms defined by the IETF, the IEEE and In addition to the OAM mechanisms defined by the IETF, the IEEE and
ITU-T have also defined various OAM mechanisms. These various ITU-T have also defined various OAM mechanisms that focus on
mechanisms defined by the three standard organizations are often Ethernet, and various other transport network environments. These
tightly coupled, and have had a mutual effect on each other. The ITU- various mechanisms, defined by the three standard organizations, are
T and IETF have both defined OAM mechanisms for MPLS LSPs, [ITU-T often tightly coupled, and have had a mutual effect on each other.
Y.1711] and [LSP Ping]. The following OAM standards by the IEEE and The ITU-T and IETF have both defined OAM mechanisms for MPLS LSPs,
ITU-T are to some extent linked to IETF OAM mechanisms listed above, [ITU-T Y.1711] and [LSP Ping]. The following OAM standards by the
and are also discussed in this document: 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 o OAM mechanisms for Ethernet based networks have been defined by
both the ITU-T in [ITU-T Y.1731], and by the IEEE in [IEEE both the ITU-T in [ITU-T Y.1731], and by the IEEE in [IEEE
802.1ag]. The IEEE 802.3 standard defines OAM for one-hop Ethernet 802.1ag]. The IEEE 802.3 standard defines OAM for one-hop Ethernet
links [IEEE 802.3ah]. links [IEEE 802.3ah].
o The ITU-T has defined OAM for MPLS LSPs in [ITU-T Y.1711]. o The ITU-T has defined OAM for MPLS LSPs in [ITU-T Y.1711].
This document summarizes the OAM mechanisms defined in the standards Table 2 summarizes the OAM standards mentioned in this document. This
above. The focus is on OAM mechanisms defined by the IETF. These document focuses on IETF OAM standards, but these non-IETF standards
mechanisms will be compared with the relevant OAM mechanisms defined are referenced where relevant.
by the ITU-T and IEEE, where applicable. We first present a
comparison of the terminology used in various OAM standards, and then
summarize the OAM functions that each OAM standard provides.
Table 1 summarizes the OAM standards discussed in this document.
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
| | Title |Standard/Draft | | | Title |Standard/Draft |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|ICMPv4 Ping| Internet Control Message Protocol | RFC 792 |
| | | |
+-----------+--------------------------------------+---------------+
|ICMPv6 Ping| Internet Control Message Protocol | RFC 4443 |
| | (ICMPv6) for the Internet Protocol | |
| | Version 6 (IPv6) Specification | |
+-----------+--------------------------------------+---------------+
|BFD | Bidirectional Forwarding Detection | RFC 5880 |
| +--------------------------------------+---------------+
| | Bidirectional Forwarding Detection | RFC 5881 |
| | (BFD) for IPv4 and IPv6 (Single Hop) | |
| +--------------------------------------+---------------+
| | Generic Application of Bidirectional | RFC 5882 |
| | Forwarding Detection | |
| +--------------------------------------+---------------+
| | Bidirectional Forwarding Detection | RFC 5883 |
| | (BFD) for Multihop Paths | |
| +--------------------------------------+---------------+
| | Bidirectional Forwarding Detection | RFC 5884 |
| | for MPLS Label Switched Paths (LSPs) | |
| +--------------------------------------+---------------+
| | Bidirectional Forwarding Detection | RFC 5885 |
| | for the Pseudowire Virtual Circuit | |
| | Connectivity Verification (VCCV) | |
+-----------+--------------------------------------+---------------+
|IETF MPLS | Operations and Management (OAM) | RFC 4377 |
|OAM | Requirements for Multi-Protocol Label| |
|(LSP Ping) | Switched (MPLS) Networks | |
| +--------------------------------------+---------------+
| | A Framework for Multi-Protocol | RFC 4378 |
| | Label Switching (MPLS) Operations | |
| | and Management (OAM) | |
| +--------------------------------------+---------------+
| | Detecting Multi-Protocol Label | RFC 4379 |
| | Switched (MPLS) Data Plane Failures | |
| +--------------------------------------+---------------+
| | Operations and Management (OAM) | RFC 4687 |
| | Requirements for Point-to-Multipoint | |
| | MPLS Networks | |
+-----------+--------------------------------------+---------------+
|MPLS-TP | Requirements for OAM in MPLS-TP | RFC 5860 |
|OAM +--------------------------------------+---------------+
| | MPLS Generic Associated Channel | RFC 5586 |
| +--------------------------------------+---------------+
| | MPLS-TP OAM Framework |[MPLS-TP OAM FW|
| | |] - work in |
| | |progress |
| +--------------------------------------+---------------+
| | MPLS-TP OAM Analysis |[OAM Analysis] |
| | | - work in |
| | |progress |
+-----------+--------------------------------------+---------------+
|PW VCCV | Pseudowire Virtual Circuit | RFC 5085 |
| | Connectivity Verification (VCCV): | |
| | A Control Channel for Pseudowires | |
+-----------+--------------------------------------+---------------+
|IPPM | Framework for IP Performance Metrics | RFC 2330 |
| +--------------------------------------+---------------+
| | IPPM Metrics for Measuring | RFC 2678 |
| | Connectivity | |
| +--------------------------------------+---------------+
| | A One-way Delay Metric for IPPM | RFC 2679 |
| +--------------------------------------+---------------+
| | A One-way Packet Loss Metric for IPPM| RFC 2680 |
| +--------------------------------------+---------------+
| | A Round-trip Delay Metric for IPPM | RFC 2681 |
| +--------------------------------------+---------------+
| | A One-way Active Measurement Protocol| RFC 4656 |
| | (OWAMP) | |
| +--------------------------------------+---------------+
| | A Two-Way Active Measurement Protocol| RFC 5357 |
| | (TWAMP) | |
+-----------+--------------------------------------+---------------+
|ITU-T | Operation & Maintenance mechanism |[ITU-T Y.1711] | |ITU-T | Operation & Maintenance mechanism |[ITU-T Y.1711] |
|MPLS OAM | for MPLS networks | | |MPLS OAM | for MPLS networks | |
| +--------------------------------------+---------------+ | +--------------------------------------+---------------+
| | Assignment of the 'OAM Alert Label' | RFC 3429 | | | Assignment of the 'OAM Alert Label' | RFC 3429 |
| | for Multiprotocol Label Switching | | | | for Multiprotocol Label Switching | |
| | Architecture (MPLS) Operation and | | | | Architecture (MPLS) Operation and | |
| | Maintenance (OAM) Functions | | | | Maintenance (OAM) Functions | |
| | | |
| | 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 Y.1711. | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|ITU-T | OAM Functions and Mechanisms for |[ITU-T Y.1731] | |ITU-T | OAM Functions and Mechanisms for |[ITU-T Y.1731] |
|Ethernet | Ethernet-based Networks | | |Ethernet | Ethernet-based Networks | |
|OAM | | | |OAM | | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|IEEE | Connectivity Fault Management |[IEEE 802.1ag] | |IEEE | Connectivity Fault Management |[IEEE 802.1ag] |
|CFM | | | |CFM | | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|IEEE | Media Access Control Parameters, |[IEEE 802.3ah] | |IEEE | Media Access Control Parameters, |[IEEE 802.3ah] |
|802.3 | Physical Layers, and Management | | |802.3 | Physical Layers, and Management | |
|link level | Parameters for Subscriber Access | | |link level | Parameters for Subscriber Access | |
|OAM | Networks | | |OAM | Networks | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
Table 1 Summary of OAM Standards Table 2 Non-IETF OAM Standards Mentioned in this Document
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 2. Basic Terminology
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [KEYWORDS].
3. Basic Terminology 2.1. Abbreviations
3.1. Abbreviations ACH Associated Channel Header
AIS Alarm Indication Signal AIS Alarm Indication Signal
APS Automatic Protection Switching
BDI Backward Defect Indication
BFD Bidirectional Forwarding Detection BFD Bidirectional Forwarding Detection
CC Continuity Check CC Continuity Check
CCM Continuity Check Message CCM Continuity Check Message
CV Connectivity Verification CV Connectivity Verification
DM Delay Measurement DM Delay Measurement
DTE Data Terminal Equipment FEC Forwarding Equivalence Class
FDI Forward Defect Indication
FFD Fast Failure Detection GAL Generic Associated Label
ICMP Internet Control Message Protocol ICMP Internet Control Message Protocol
L2TP Layer Two Tunneling Protocol L2TP Layer Two Tunneling Protocol
LCCE L2TP Control Connection Endpoint LCCE L2TP Control Connection Endpoint
LDP Label Distribution Protocol
LM Loss Measurement LM Loss Measurement
LSP Label Switching Path LOC Loss Of Continuity
LSP Label Switched Path
LSR Label Switching Router LSR Label Switching Router
MA Maintenance Association
ME Maintenance Entity ME Maintenance Entity
MEG Maintenance Entity Group MEG Maintenance Entity Group
MEP Maintenance End Point MEP MEG End Point
MHF MIP Half Function
MIP Maintenance Intermediate Point MIP MEG Intermediate Point
MP Maintenance Point MP Maintenance Point
MPLS Multiprotocol Label Switching MPLS Multiprotocol Label Switching
MPLS-TP MPLS Transport Profile MPLS-TP MPLS Transport Profile
MTU Maximum Transmission Unit
OAM Operations, Administration, and Maintenance OAM Operations, Administration, and Maintenance
PE Provider Edge PE Provider Edge
PW Pseudowire PW Pseudowire
PWE3 Pseudowire Emulation Edge-to-Edge PWE3 Pseudowire Emulation Edge-to-Edge
RDI Remote Defect Indication RDI Remote Defect Indication
TTL Time To Live TTL Time To Live
TTSI Trail Termination Source Identifier
VCCV Virtual Circuit Connectivity Verification VCCV Virtual Circuit Connectivity Verification
3.2. Terminology used in OAM Standards 2.2. Terminology used in OAM Standards
3.2.1. General Terms 2.2.1. General Terms
A wide variety of terms is used in various OAM standards. Each of the 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 OAM standards listed in the reference section includes a section that
defines the relevant terms. A thesaurus of terminology for MPLS-TP defines terms relevant to that tool. A thesaurus of terminology for
terms is presented in [MPLS-TP Term], and provides a good summary of MPLS-TP terms is presented in [MPLS-TP Term], and provides a good
some of the OAM related terminology. summary of some of the OAM related terminology.
This section presents a comparison of the terms used in various OAM This section presents a comparison of the terms used in various OAM
standards, without fully quoting the definition of each term. For a standards, without fully quoting the definition of each term. For a
formal definition of each term, refer to the references at the end of formal definition of each term, refer to the references at the end of
this document. The comparison focuses on three basic terms, and is this document.
summarized in section 3.2.6.
3.2.2. OAM Maintenance Entities and Communication Links 2.2.2. OAM Maintenance Entities
A Maintenance Entity (ME) is a point-to-point relationship between OAM tools are designed to monitor and manage a Maintenance Entity
two Maintenance Points (MP). The connectivity between these (ME). An ME, as defined in [TP OAM FW], defines a relationship
Maintenance Points is managed and monitored by the OAM protocol. between two points of a transport path to which maintenance and
monitoring operations apply.
A pair of MPs engaged in an ME are connected by a communication Link. The following related terms are also quoted from [TP OAM FW]:
The term "Link" in this context is a generic term that may refer to
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 Link is used throughout this document to refer
to the connection between the MPs that is monitored by an OAM
protocol.
The term Maintenance Entity (ME) is defined in ITU-T standards (e.g. o MEP: The two points that define a maintenance entity.
[ITU-T Y.1731]). Various terms are used to refer to an ME. For
example, in MPLS LSP Ping ([LSP Ping]) terminology, an ME is simply o MEG: The collection of one or more MEs that belongs to the same
referred to as an LSP. BFD does not explicitly use a term that is transport path and that are maintained and monitored as a group
equivalent to ME, but rather uses the term "session", referring to are known as a Maintenance Entity Group (MEG).
the relationship between two nodes using a BFD protocol.
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 Y.1731]), 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) MPLS-TP has defined the terms ME and Maintenance Entity Group (MEG)
in [MPLS-TP OAM FW], similar to the terms defined by ITU-T. 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.
3.2.3. OAM Maintenance Points 2.2.3. OAM Maintenance Points
A Maintenance Point (MP) is a functional entity that is defined at a 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. 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 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 can initiate OAM messages and respond to them. A Maintenance
Intermediate Point (MIP) is an intermediate point between two MEPs, Intermediate Point (MIP) is an intermediate point between two MEPs,
that does not initiate OAM frames, but is able to respond to OAM that does not generally initiate OAM frames (one exception to this is
frames that are destined to it, and to forward others. 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
The terms MEP and MIP are defined in ITU-T standards (e.g. [ITU-T destined to it by the value of the TTL field in the OAM packet. The
Y.1731]). The term Maintenance Point is a general term for MEPs and term Maintenance Point is a general term for MEPs and MIPs.
MIPs, and is used in [IEEE 802.1ag].
The 802.1ag defines a finer distinction between Up MPs and Down MPs. 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 An MP is a bridge interface, that is monitored by an OAM protocol
either in the direction facing the network, or in the direction 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, 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 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 OAM packets from, and transmits them to the direction of the bridging
entity. entity.
MPLS-TP has defined the terms MEP and MIP and their functional MPLS-TP ([TP OAM FW]) uses a similar distinction on the placement of
characteristics in [MPLS-TP OAM FW], similar to the terms defined by the MP - either at the ingress, egress, or forwarding function of the
ITU-T. node (Down / Up MPs). This placement is important for localization
of a connection failure.
3.2.4. Connectivity Verification and Continuity Checks 2.2.4. Proactive and On-demand activation
The different OAM tools may be used in one of two basic types of
activation:
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.
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 Two distinct classes of failure management functions are used in OAM
protocols, connectivity verification and continuity checks. The protocols, connectivity verification and continuity checks. The
distinction between these terms is defined in [MPLS-TP OAM], and is distinction between these terms is defined in [MPLS-TP OAM], and is
used similarly in this document. used similarly in this document.
Continuity checks are used to verify the liveness of a link, and are Continuity checks are used to verify the liveness of a connection or
typically sent proactively, though they can be invoked on-demand as a path between two MPs, and are typically sent proactively, though
well. they can be invoked on-demand as well.
A connectivity verification function allows an MP to check whether it A connectivity verification function allows an MP to check whether it
is connected to a peer MP or not. A connectivity verification (CV) is connected to a peer MP or not. This function also allows the MP to
protocol typically uses a CV message, followed by a CV reply that is verify that messages from the peer MP are received through the
sent back to the originator. A CV function can be applied proactively correct path, thereby verifying not only that the two MPs are
or on-demand. 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 Connectivity verification and continuity checks are considered
complementary mechanisms, and are often used in conjunction with each complementary mechanisms, and are often used in conjunction with each
other. other.
3.2.5. Link Failures 2.2.6. Failures
The terms Failure, Fault, and Defect are intermittently used in the The terms Failure, Fault, and Defect are used interchangeably in the
standards, referring to a malfunction that can be detected by a standards, referring to a malfunction that can be detected by a
connectivity or a continuity check. In some standards, such as [IEEE connectivity or a continuity check. In some standards, such as [IEEE
802.1ag], there is no distinction between these terms, while in other 802.1ag], there is no distinction between these terms, while in other
standards each of these terms refers to a different type of standards each of these terms refers to a different type of
malfunction. malfunction.
The ITU-T distinguishes between these terms in [ITU-T G.806]. The The terminology used in IETF MPLS-TP OAM takes after the ITU-T, which
term Fault refers to an inability to perform a required action, e.g., distinguishes between these terms in [ITU-T G.806]; The term Fault
an unsuccessful attempt to deliver a packet. The term Defect refers refers to an inability to perform a required action, e.g., an
to an interruption in the normal operation, such as a consecutive unsuccessful attempt to deliver a packet. The term Defect refers to
period of time where no packets are delivered successfully. The term an interruption in the normal operation, such as a consecutive period
Failure refers to the termination of the required function. While a of time where no packets are delivered successfully. The term Failure
Defect typically refers to a limited period of time, a failure refers refers to the termination of the required function. While a Defect
to a long period of time. typically refers to a limited period of time, a failure refers to a
long period of time.
3.2.6. Summary of OAM Terms used in the Standards
Table 2 provides a comparison of the terminology used in different
OAM standards.
+-----------+-------------+-----------+----------------------------+
| |Maintenance |Maintenance|Link Failure Terminology |
| |Point |Entity | |
| |Terminology |Terminology| |
+-----------+-------------+-----------+----------------------------+
|ICMPv4 Ping|-Host | | |
| |-Gateway | | |
+ --------- + ----------- + --------- + -------------------------- +
|ICMPv6 Ping| Node | | |
+ --------- + ----------- + --------- + -------------------------- +
|BFD | System | Session |-Failure |
| | | |-Session is declared down |
+ --------- + ----------- + --------- + -------------------------- +
|LSP Ping | LSR | LSP |-Failure |
| | | |-Fault = typically a local |
| | | | isolated failure |
+ --------- + ----------- + --------- + -------------------------- +
|PW VCCV |-PE | PW |-Failure |
| |-LCCE | |-Fault |
+ --------- + ----------- + --------- + -------------------------- +
|IPPM |-Host |-Path | Connectivity is indicated |
| |-End system |-Measuremen| by a Boolean value. Thus, |
| | | t session | a failure is referred to as|
| | | | a path with a measurement |
| | | | value "false". |
+ --------- + ----------- + --------- + -------------------------- +
|ITU-T | LSR | LSP |-Fault, Defect, Failure: as |
|Y.1711 | | | defined in [ITU-T G.806] |
+ --------- + ----------- + --------- + -------------------------- +
|ITU-T |-MEP | ME |-Fault, Defect, Failure: as |
|Y.1731 |-MIP | | defined in [ITU-T G.806] |
| | | | |
+ --------- + ----------- + --------- + -------------------------- +
|MPLS-TP |-End Point, |-LSP |-Fault, Defect, Failure: as |
|OAM | MEP |-PW | defined in [ITU-T G.806] |
| |-Intermediate|-Section | |
| | Point, MIP | | |
+ --------- + ----------- + --------- + -------------------------- +
|IEEE |-MP (Down,Up)| ME |-Failure |
|802.1ag | -MEP | |-Fault |
| | -MIP | |-Defect |
| | -MHF | | |
+ --------- + ----------- + --------- + -------------------------- +
|IEEE | DTE | Link |-Failure |
|802.3ah | | |-Fault |
+-----------+-------------+-----------+----------------------------+
Table 2 Summary of OAM Terms
4. OAM Functions 3. OAM Tools
4.1. ICMP Ping 3.1. ICMP Ping
ICMP provides a connectivity verification function for the Internet ICMP provides a connectivity verification function for the Internet
Protocol. The originator transmits an echo request packet, and the Protocol. The originator transmits an ICMP Echo request packet, and
receiver replies with an echo reply. ICMP ping is defined in two 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. variants, [ICMPv4] is used for IPv4, and [ICMPv6] is used for IPv6.
ICMP is also used in Traceroute for path discovery. Traceroute allows 3.2. Traceroute
a host to detect the path to a destination host, as follows:
o The originator host repeatedly transmits an ICMP message to the Traceroute ([TCPIP Tools]) is an application that allows users to
destination host. At first, the value of the Time To Live (TTL) discover the path between an IP source and an IP destination.
field in the ICMP message is 1, and is then repeatedly incremented Traceroute sends a sequence of UDP packets to UDP port 33434 at the
by 1. destination. By default, Traceroute begins by sending three packets,
each with an IP Time-To-Live (TTL) value of one to the destination.
o In turn, each router on the traversing path returns an ICMP These packets expire as soon as they reach the first router in the
message to the originator with an ICMP Time Exceeded error path. That router responds by sending three ICMP Time Exceeded
message. 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.
o Finally, the destination router replies with an ICMP Echo Reply. Note that IP routing may be asymmetric. While Traceroute reveals the
path between a source and destination, it may not reveal the reverse
path.
4.2. Bidirectional Forwarding Detection (BFD) 3.3. Bidirectional Forwarding Detection (BFD)
4.2.1. Overview 3.3.1. Overview
While multiple OAM mechanisms have been defined for various protocols While multiple OAM mechanisms have been defined for various protocols
in the protocol stack, Bidirectional Forwarding Detection [BFD], in the protocol stack, Bidirectional Forwarding Detection [BFD],
defined by the IETF BFD working group, is a generic OAM mechanism defined by the IETF BFD working group, is a generic OAM mechanism
that can be deployed over various encapsulating protocols, and in that can be deployed over various encapsulating protocols, and in
various medium types. The IETF has defined variants of the protocol 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 for IP ([BFD IP], [BFD Multi]), for MPLS LSPs [BFD LSP], and for PWE3
[BFD VCCV]. BFD for MPLS-TP is currently evolving in the MPLS working [BFD VCCV]. The usage of BFD in MPLS-TP is defined in [MPLS-TP CC
group (e.g. [MPLS-TP Ping BFD]). CV].
BFD includes two main OAM functions, using two types of BFD packets: BFD includes two main OAM functions, using two types of BFD packets:
BFD Control packets, and BFD Echo packets. BFD Control packets, and BFD Echo packets.
4.2.2. BFD Control 3.3.2. BFD Control
BFD supports a bidirectional continuity check, using BFD control BFD supports a bidirectional continuity check, using BFD control
packets, that are exchanged within a BFD session. BFD sessions packets, that are exchanged within a BFD session. BFD sessions
operate in one of two modes: operate in one of two modes:
o Asynchronous mode: in this mode BFD control packets are sent o Asynchronous mode (i.e. proactive): in this mode BFD control
periodically. When the receiver detects that no BFD control packet packets are sent periodically. When the receiver detects that no
have been received during a predetermined period of time, a BFD control packet have been received during a predetermined
failure is detected. period of time, a failure is detected.
o Demand mode: in this mode, BFD control packets are sent on-demand. 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 Upon need, a system initiates a series of BFD control packets to
verify the link. BFD control packets are sent independently in verify the liveness of the session. BFD control packets are sent
each direction of the link. independently in each direction.
Each of the end-points of the monitored path maintains its own Each of the end-points of the monitored path maintains its own
session identification, called a Discriminator, both of which are session identification, called a Discriminator, both of which are
included in the BFD Control Packets that are exchanged between the included in the BFD Control Packets that are exchanged between the
end-points. At the time of session establishment, the Discriminators end-points. At the time of session establishment, the Discriminators
are exchanged between the two-end points. In addition, the are exchanged between the two-end points. In addition, the
transmission (and reception) rate is negotiated between the two end- transmission (and reception) rate is negotiated between the two end-
points, based on information included in the control packets. These points, based on information included in the control packets. These
transmission rates may be renegotiated during the session. transmission rates may be renegotiated during the session.
During normal operation of the session, i.e. no failures are During normal operation of the session, i.e. no failures are
detected, the BFD session is in the Up state. If no BFD Control detected, the BFD session is in the Up state. If no BFD Control
packets are received during a fixed period of time, called the packets are received during a fixed period of time, called the
Detection Time, the session is declared to be Down. The detection Detection Time, the session is declared to be Down. The detection
time is a function of the negotiated transmission time, and a time is a function of the negotiated transmission time, and a
parameter called Detect Mult. Detect Mult determines the number of parameter called Detect Mult. Detect Mult determines the number of
missing BFD Control packets that cause the session to be declared as missing BFD Control packets that cause the session to be declared as
Down. This parameter is included in the BFD Control packet. Down. This parameter is included in the BFD Control packet.
4.2.3. BFD Echo 3.3.3. BFD Echo
The echo function is used for connectivity verification. A BFD echo A BFD echo packet is sent to a peer system, and is looped back to the
packet is sent to a peer system, and is looped back to the
originator. The echo function can be used proactively, or on-demand. originator. The echo function can be used proactively, or on-demand.
4.3. LSP Ping 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.
3.4. LSP Ping
The IETF MPLS working group has defined OAM for MPLS LSPs. The The IETF MPLS working group has defined OAM for MPLS LSPs. The
requirements and framework of this effort was defined in [MPLS OAM requirements and framework of this effort are defined in [MPLS OAM
FW] and [MPLS OAM], respectively. The corresponding OAM mechanism FW] and [MPLS OAM], respectively. The corresponding OAM mechanism
defined, in this context, is LSP Ping [LSP Ping]. defined, in this context, is LSP Ping [LSP Ping].
LSP Ping is based on ICMP Ping and just like its predecessor may be LSP Ping is based on ICMP Ping and just like its predecessor may be
used in one of two modes: used in one of two modes:
o "Ping" mode: In this mode LSP ping is used for end-to-end o "Ping" mode: In this mode LSP ping is used for end-to-end
connectivity verification between two LSRs. connectivity verification between two LERs.
o "Traceroute" mode: This mode is used for hop-by-hop fault o "Traceroute" mode: This mode is used for hop-by-hop fault
localization. isolation.
LSP Ping extends the basic ICMP Ping operation (of data-plane LSP Ping extends the basic ICMP Ping operation (of data-plane
connectivity and continuity check) with functionality to verify connectivity verification) with functionality to verify data-plane
data-plane vs. control-plane consistency for a Forwarding Equivalence vs. control-plane consistency for a Forwarding Equivalence Class
Class (FEC) and also Maximum Transmission Unit (MTU) problems. The (FEC) and also Maximum Transmission Unit (MTU) problems. The
traceroute functionality may be used to isolate and localize the MPLS traceroute functionality may be used to isolate and localize the MPLS
faults, using the Time-to-live (TTL) indicator to incrementally faults, using the Time-to-live (TTL) indicator to incrementally
identify the sub-path of the LSP that is successfully traversed identify the sub-path of the LSP that is successfully traversed
before the faulty link or node. before the faulty link or node.
It should be noted that LSP Ping does support unique identification It should be noted that LSP Ping supports unique identification of
of the LSP within an addressing domain. The identification is checked the LSP within an addressing domain. The identification is checked
using the full FEC identification. LSP Ping is easily extensible to using the full FEC identification. LSP Ping is easily extensible to
include additional information needed to support new functionality, include additional information needed to support new functionality,
by use of Type-Length-Value (TLV) constructs. The usage of TLVs is by use of Type-Length-Value (TLV) constructs. The usage of TLVs is
typically not easy to perform in hardware, and is thus typically typically not easy to perform in hardware, and is thus typically
handled by the control plane. handled by the control plane.
LSP Ping supports both asynchronous, as well as, on-demand LSP Ping supports both asynchronous, as well as, on-demand
activation. In addition, extensions for LSP Ping are being defined activation.
for point-to-multipoint LSPs in [P2MP LSP Ping] and for MPLS Tunnels
in [MPLS LSP Ping].
4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV) 3.5. PWE3 Virtual Circuit Connectivity Verification (VCCV)
VCCV, as defined in [VCCV], provides end-to-end fault detection VCCV, as defined in [VCCV], provides a means for end-to-end fault
and diagnostics for PWs (regardless of the underlying tunneling detection and diagnostics tools to be extended for PWs (regardless of
technology). The VCCV switching function provides a control channel the underlying tunneling technology). The VCCV switching function
associated with each PW (based on the PW Associated Channel Header provides a control channel associated with each PW (based on the PW
(ACH) which is defined in [PW ACH]), and allows sending OAM packets Associated Channel Header (ACH) which is defined in [PW ACH]), and
in-band with PW data (using CC Type 1: In-band VCCV). 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 VCCV currently supports the following OAM mechanisms: ICMP Ping, LSP
Ping, and BFD. ICMP and LSP Ping are IP encapsulated before being Ping, and BFD. ICMP and LSP Ping are IP encapsulated before being
sent over the PW ACH. BFD for VCCV supports two modes of sent over the PW ACH. BFD for VCCV supports two modes of
encapsulation - either IP/UDP encapsulated (with IP/UDP header) or encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
PW-ACH encapsulated (with no IP/UDP header) and provides support to PW-ACH encapsulated (with no IP/UDP header) and provides support to
signal the AC status. The use of the VCCV control channel provides signal the AC status. The use of the VCCV control channel provides
the context, based on the MPLS-PW label, required to bind and the context, based on the MPLS-PW label, required to bind and
bootstrap the BFD session to a particular pseudo wire (FEC), bootstrap the BFD session to a particular pseudo wire (FEC),
eliminating the need to exchange Discriminator values. eliminating the need to exchange Discriminator values.
skipping to change at page 16, line 34 skipping to change at page 17, line 7
VCCV consists of two components: (1) signaled component to VCCV consists of two components: (1) signaled component to
communicate VCCV capabilities as part of VC label, and (2) switching communicate VCCV capabilities as part of VC label, and (2) switching
component to cause the PW payload to be treated as a control packet. 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. VCCV is not directly dependent upon the presence of a control plane.
The VCCV capability negotiation may be performed as part of the PW The VCCV capability negotiation may be performed as part of the PW
signaling when LDP is used. In case of manual configuration of the signaling when LDP is used. In case of manual configuration of the
PW, it is the responsibility of the operator to set consistent PW, it is the responsibility of the operator to set consistent
options at both ends. options at both ends.
4.5. IP Performance Metrics (IPPM) 3.6. IP Performance Metrics (IPPM)
4.5.1. Overview 3.6.1. Overview
The IPPM working group [IPPM FW] in the IETF defines common criteria The IPPM working group in the IETF defines common criteria and
and metrics for measuring performance of IP traffic. Some of the key metrics for measuring performance of IP traffic ([IPPM FW]). Some of
RFCs published by this working group have defined metrics for the key RFCs published by this working group have defined metrics for
measuring connectivity [IPPM Con], delay ([IPPM 1DM], [IPPM 2DM]), measuring connectivity [IPPM Con], delay ([IPPM 1DM], [IPPM 2DM]),
and packet loss [IPPM 1LM]. 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 Y.1731].
The IPPM working group has defined not only metrics for performance The IPPM working group has defined not only metrics for performance
measurement, but also protocols that define how the measurement is measurement, but also protocols that define how the measurement is
carried out. The One-way Active Measurement Protocol [OWAMP] and the carried out. The One-way Active Measurement Protocol [OWAMP] and the
Two-Way Active Measurement Protocol [TWAMP] define a method and Two-Way Active Measurement Protocol [TWAMP] define a method and
protocol for measuring delay and packet loss in IP networks. protocol for measuring delay and packet loss in IP networks.
OWAMP [OWAMP] enables measurement of one-way characteristics of IP OWAMP [OWAMP] enables measurement of one-way characteristics of IP
networks, such as one-way packet loss and one-way delay. For its networks, such as one-way packet loss and one-way delay. For its
proper operation OWAMP requires accurate time of day setting at its proper operation OWAMP requires accurate time of day setting at its
end points. end points.
TWAMP [TWAMP] is a similar protocol that enables measurement of two- TWAMP [TWAMP] is a similar protocol that enables measurement of two-
way (round trip) characteristics. TWAMP does not require accurate way (round trip) characteristics. TWAMP does not require accurate
time of day, and, furthermore, allows the use of a simple session time of day, and, furthermore, allows the use of a simple session
reflector, making it an attractive alternative to OWAMP. reflector, making it an attractive alternative to OWAMP.
OWAMP and TWAMP use two separate protocols: a Control plane protocol, OWAMP and TWAMP use two separate protocols: a Control plane protocol,
and a Test plane protocol. and a Test plane protocol.
4.5.2. Control and Test Protocols 3.6.2. Control and Test Protocols
OWAMP and TWAMP control protocols run over TCP, while the test OWAMP and TWAMP control protocols run over TCP, while the test
protocols run over UDP. The purpose of the control protocols is to protocols run over UDP. The purpose of the control protocols is to
initiate, start, and stop test sessions, and for OWAMP to fetch initiate, start, and stop test sessions, and for OWAMP to fetch
results. The test protocols introduce test packets (which contain results. The test protocols introduce test packets (which contain
sequence numbers and timestamps) along the IP path under test sequence numbers and timestamps) along the IP path under test
according to a schedule, and record statistics of packet arrival. according to a schedule, and record statistics of packet arrival.
Multiple sessions may be simultaneously defined, each with a session Multiple sessions may be simultaneously defined, each with a session
identifier, and defining the number of packets to be sent, the amount 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, 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 and the send schedule (which can be either a constant time between
test packets or exponentially distributed pseudo-random). Statistics test packets or exponentially distributed pseudo-random). Statistics
recorded conform to the relevant IPPM RFCs. recorded conform to the relevant IPPM RFCs.
OWAMP and TWAMP test traffic is designed with security in mind. Test OWAMP and TWAMP test traffic is designed with security in mind. Test
packets are hard to detect because they are simply UDP streams packets are hard to detect because they are simply UDP streams
between negotiated port numbers, with potentially nothing static in between negotiated port numbers, with potentially nothing static in
the packets. OWAMP and TWAMP also include optional authentication the packets. OWAMP and TWAMP also include optional authentication
and encryption for both control and test packets. and encryption for both control and test packets.
4.5.3. OWAMP 3.6.3. OWAMP
OWAMP defines the following logical roles: Session-Sender, Session- OWAMP defines the following logical roles: Session-Sender, Session-
Receiver, Server, Control-Client, and Fetch-Client. The Session- Receiver, Server, Control-Client, and Fetch-Client. The Session-
Sender originates test traffic that is received by the Session- Sender originates test traffic that is received by the Session-
Receiver. The Server configures and manages the session, as well as Receiver. The Server configures and manages the session, as well as
returning the results. The Control-Client initiates requests for returning the results. The Control-Client initiates requests for
test sessions, triggers their start, and may trigger their test sessions, triggers their start, and may trigger their
termination. The Fetch-Client requests the results of a completed termination. The Fetch-Client requests the results of a completed
session. Multiple roles may be combined in a single host - for session. Multiple roles may be combined in a single host - for
example, one host may play the roles of Control-Client, Fetch-Client, example, one host may play the roles of Control-Client, Fetch-Client,
skipping to change at page 18, line 20 skipping to change at page 18, line 43
describes a test session to which the Server responds with its describes a test session to which the Server responds with its
acceptance and supporting information. More than one test session acceptance and supporting information. More than one test session
may be requested with additional messages. The Control-Client then may be requested with additional messages. The Control-Client then
starts a test session and the Server acknowledges. The Session- starts a test session and the Server acknowledges. The Session-
Sender then sends test packets with pseudorandom padding to the Sender then sends test packets with pseudorandom padding to the
Session-Receiver until the session is complete or until the Control- Session-Receiver until the session is complete or until the Control-
client stops the session. Once finished, the Fetch-Client sends a client stops the session. Once finished, the Fetch-Client sends a
fetch request to the server, which responds with an acknowledgement fetch request to the server, which responds with an acknowledgement
and immediately thereafter the result data. and immediately thereafter the result data.
4.5.4. TWAMP 3.6.4. TWAMP
TWAMP defines the following logical roles: session-sender, session- TWAMP defines the following logical roles: session-sender, session-
reflector, server, and control-client. These are similar to the reflector, server, and control-client. These are similar to the
OWAMP roles, except that the Session-Reflector does not collect any OWAMP roles, except that the Session-Reflector does not collect any
packet information, and there is no need for a Fetch-Client. packet information, and there is no need for a Fetch-Client.
In a typical TWAMP session the Control-Client establishes a TCP In a typical TWAMP session the Control-Client establishes a TCP
connection to port 862 of the Server, and mode is negotiated as in connection to port 862 of the Server, and mode is negotiated as in
OWAMP. The Control-Client then requests sessions and starts them. OWAMP. The Control-Client then requests sessions and starts them.
The Session-Sender sends test packets with pseudorandom padding to The Session-Sender sends test packets with pseudorandom padding to
the Session-Reflector which returns them with insertion of the Session-Reflector which returns them with insertion of
timestamps. timestamps.
4.6. ITU-T Y.1711 3.7. MPLS-TP OAM
4.6.1. Overview
As mentioned above (4.3.), the IETF defined LSP Ping as an OAM
mechanism for MPLS. The ITU-T has also defined an OAM protocol for
MPLS, defined in recommendation [ITU-T Y.1711]. This recommendation
defines mechanisms for connectivity verification and fast failure
detection, as well as mechanism for reporting defects that have been
identified in an LSP.
MPLS OAM packets per Y.1711 are detected by a reserved MPLS label
value. The reserved value is 14, and is defined in [OAM Label] as the
'OAM Alert Label'.
4.6.2. Connectivity Verification (CV)
The CV function is used to detect connectivity defects in an LSP. CV
frames are sent proactively at a rate of 1 per second. Each frame
contains the Trail-Termination Source Identifier (TTSI), indicating
the identity of the transmitting LSR.
The CV function can detect any of the following defect conditions.
o Loss of Connectivity Verification (LOCV): A loss of connectivity
is detected when no CV OAM packets are received in a period of 3
consecutive transmission periods.
It should be noted that the LOCV defect is in fact loss of
continuity when using the terminology defined in 3.2.4.
o TTSI Mismatch: A TTSI mismatch is detected when a CV frame with an
unexpected TTSI is received.
o TTSI Mismerge: A TTSI mismerge is detected when the CV frames
received in a given LSP contain some frame with an expected TTSI,
and some frames with an unexpected TTSI.
o Excess: An excess is detected when at least 5 CV frames are
received during a period of 3 consecutive transmission periods.
4.6.3. Fast Failure Detection (FFD)
The FFD function is a proactive function, used for fast detection of
connectivity defects. While CV is typically sufficient for path
failure detection and reporting, protection switching mechanisms
typically require faster detection. FFD is very similar to CV in
terms of the packet format, and the possible defect conditions, but
FFD allows a configurable transmission frequency. The default
transmission rate of FFD frames is 20 per second, i.e., every 50 ms,
allowing fast detection for protection switching applications.
4.6.4. Forward Defect Indication (FDI)
The FDI function is used by an LSR to report a defect to affected
client layers, allowing them to suppress alarms about this defect.
In MPLS-TP OAM this function is referred to as Client Failure
Indication.
FDI packets are sent at a rate of 1 per second.
4.6.5. Backward Defect Indication (BDI)
The BDI function is used by an LSR to inform a peer LSR about a
defect condition on an LSP for which they are the end points of.
In MPLS-TP OAM this function is referred to as Remote Defect
Indication.
BDI packets are sent at the same transmission rate as FDI.
4.7. ITU-T Y.1731
4.7.1. Overview
The [ITU-T Y.1731] defines a protocol for Ethernet OAM. It is
presented in this document as a reference point. Y.1731 defines
various OAM functions, including continuity and connectivity
verification, and functions for performance monitoring.
4.7.2. ETH-CC
The Ethernet Continuity Check function is a proactive function that
allows a MEP to detect loss of continuity with any of the other MEPs
in the MEG. This function also allows detection of other defect
conditions, such as unintended connectivity between two MEGs (also
known as a mismerge). The ETH-CC function is used for one of three
possible applications: fault management, performance monitoring (see
4.6.10.), and protection switching.
Continuity Check Messages (CCM) are transmitted periodically at a
constant rate. There are 7 possible transmission periods, from 3.33
ms to 10 min. When the ETH-CC function detects a defect, it reports
one of the following defect conditions:
o Loss of continuity (LOC): Occurs when at least when no CCM
messages have been received from a peer MEP during a period of 3.5
times the configured transmission period.
o Unexpected MEG level: The MEG level is a 3-bit number that defines
the level of hierarchy of the MEG. This defect condition occurs
when a CCM is received from a peer MEP with a MEG level that is
lower than the expected MEG level.
o Mismerge: Occurs when a CCM is received from a peer MEP with an
unexpected MEG ID.
o Unexpected MEP: Occurs when a CCM is received from a peer MEP with
an unexpected transmitting MEP ID.
o Unexpected period: Occurs when the transmission period field in
the CCM does not match the expected transmission period value.
4.7.3. ETH-LB
The Ethernet loopback function verifies connectivity with a peer MEP
or MIP. The loopback function is performed on-demand, by sending a
loopback message (LBM) to the peer MEP or MIP. The peer node then
responds with a loopback reply (LBR).
More precisely, it is used for one of two purposes:
o Bidirectional connectivity test.
o Bidirectional in-service / out-of-service test. The in-service
mode refers to a test that is run under traffic, while the out-of-
service test requires other traffic to be halted.
4.7.4. ETH-TST
The test function is very similar to the loopback function, but is
unidirectional, i.e., the ETH-TST PDUs are terminated by the receiver
rather than being looped back to the sender.
4.7.5. ETH-LT
The Ethernet linktrace is an on-demand function that is used for path
discovery to a given target, or for locating a failure in a broken
path.
4.7.6. ETH-AIS
The Alarm Indication Signal indicates that a MEG should suppress
alarms about a defect condition at a lower MEG level, i.e., since a
defect has occurred in a lower hierarchy in the network, it should
not be reported by the current node.
A MEP that detects a failure periodically sends AIS messages to
higher hierarchies. AIS messages are sent periodically at a
recommended rate of 1 packet per second, until the defect condition
is resolved.
4.7.7. ETH-LCK
The lock function is used for administrative locking. A MEP can
initiate administrative locking, resulting in interruption of data,
e.g., for out-of-service ETH-LB or ETH-TST.
A MEP that initiates an administrative locking notifies its peer MEPs
to halt all relevant traffic until administrative/diagnostic
condition is removed. ETH-LCK frames are used to report to higher MEG
levels about the lock. The LCK frame, much like an AIS frame,
indicates to the receiving MEP that it should suppress alarms about
the locked link.
4.7.8. ETH-RDI
The Remote Defect Indication allows the sender to indicate that it
encountered a defect conditions. The receiving MEPs are then aware
that there is a defect condition in the MEG.
4.7.9. ETH-APS
The Y.1731 standard defines the frame format for Automatic Protection
Switching frames. The protection switching operations are defined in
other ITU-T standards.
4.7.10. ETH-LM
The loss measurement function allows a MEP to measure the packet loss
rate from/to a given MEP in the MEG. Each MEP maintains counters of
transmitted and received in-profile packets to/from each of its peer
MEPs. These counters are incorporated in the ETH-LM frames, allowing
the MEPs to compute the packet loss rate.
The ETH-LM function measures the far-end loss, referring to traffic
FROM the MEP to its peer, as well as the near-end loss, referring to
traffic from the peer MEP TO the local MEP.
ETH-LM is performed in one of two possible modes:
o Single-ended LM: in this mode loss measurement is performed on-
demand. The initiator sends an LM message (LMM) to its peer MEP,
and the peer responds with an LM reply (LMR).
o Dual-ended LM: in this mode loss measurement is performed
proactively. The continuity check message (CCM) is used for
proactive LM. The LM counters are piggy-backed into the CCM, and
allow proactive loss measurement.
4.7.11. ETH-DM
The delay measurement function is an on-demand function that allows a
MEP to measure the frame delay and frame delay variation to a peer
MEP.
ETH-DM can be performed in one of two modes of operation:
o One-way DM: in this mode, a MEP transmits a 1DM frame containing
the time of its transmission, TxTimeStampf. The receiving MEP
receives the 1DM frame and records the time of reception, RxTimef.
The receiving MEP can then compute the one-way delay by: RxTimef -
TxTimeStampf.
o Two-way DM: in this mode, a MEP transmits a delay measurement
message (DMM) containing its transmission time, TxTimeStampf. The
peer MEP receives the DMM and responds with a delay measurement
reply (DMR). Upon receiving the DMR, the initiating MEP records
the time of its reception, RxTimef, and computes the round trip
delay by: RxTimef - TxTimeStampf.
Each MEP maintains a time-of-day clock that is used for timestamping
delay measurement frames. It should be noted that in one-way DM it is
implicitly assumed that the clocks of the two peer MEPs are
synchronized by a time synchronization protocol.
4.8. IEEE 802.1ag
4.8.1. Overview
While the [ITU-T Y.1731] was defined in the ITU-T, the IEEE defined
the [IEEE 802.1ag] as a standard for connectivity fault management in
Ethernet based networks. While the two standards are to some extent
overlapping, they can also be viewed as two complementary parts of a
single Ethernet OAM picture. The two standards use a common packet
format. There are a few differences between the two standards in
terms of terminology: the term MEG level, used in Y.1731, as referred
to as Maintenance Domain level in 802.1ag; the Y.1731 standard uses
the term MEG, while the 802.1ag equivalent is Maintenance Association
(MA).
While Y.1731 defines multiple OAM functions (see section 4.6), the
802.1ag standard focuses on three main OAM functions: continuity
check, loopback, and linktrace, and defines them with great detail.
4.8.2. Continuity Check
See 4.6.2.
4.8.3. Loopback
See 4.6.3.
4.8.4. Linktrace
See 4.6.5.
4.9. IEEE 802.3ah
4.9.1. Overview
The [IEEE 802.3ah] defines Ethernet for the Last Mile (EFM). With
respect to OAM, this standard was designed as an Ethernet link-layer
OAM, for single-hop Ethernet links, allowing to monitor remote
networking devices that are not managed by a centralized management
system. The OAM functions in this standard are described below.
4.9.2. Remote Failure Indication
This function allows a node to notify a peer about a defect in the
receive path. Some physical interfaces allow unidirectional traffic,
where even if one direction of the link fails, the reverse direction
can still be used to convey the remote failure indication.
4.9.3. Remote Loopback
The remote loopback function provides a diagnostic mode that is used
to verify the link connectivity, and to measure the packet loss rate.
When a bridge interface is configured to loopback mode, all incoming
traffic through the interface is looped and sent back to the
originator.
4.9.4. Link Monitoring
Link monitoring provides an event notification function, allowing
peer devices to communicate defect conditions and diagnostic
information.
4.10. MPLS-TP OAM
4.10.1. Overview 3.7.1. Overview
The MPLS working group is currently working on defining the OAM The MPLS working group is currently working on defining the OAM
toolset that fulfill the requirements for MPLS-TP OAM. The full set 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 of requirements for MPLS-TP OAM are defined in [MPLS-TP OAM], and
include both general requirements for the behavior of the OAM include both general requirements for the behavior of the OAM
mechanisms and a set of operations that should be supported by the mechanisms and a set of operations that should be supported by the
OAM toolset. The set of mechanisms required are further elaborated OAM toolset. The set of mechanisms required are further elaborated
in [MPLS-TP OAM FW], that describes the general architecture of the in [TP OAM FW], which describes the general architecture of the OAM
OAM system as well as giving overviews of the functionality of the system as well as giving overviews of the functionality of the OAM
OAM toolset. toolset.
Some of the basic requirements for the OAM toolset for MPLS-TP are: 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 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 based environment. If the network is IP based, i.e. IP routing and
forwarding are available, then the MPLS-TP OAM toolset should rely forwarding are available, then the MPLS-TP OAM toolset should rely
on the IP routing and forwarding capabilities. On the other hand, on the IP routing and forwarding capabilities. On the other hand,
in environments where IP functionality is not available, the OAM in environments where IP functionality is not available, the OAM
tools must still be able to operate without dependence on IP tools must still be able to operate without dependence on IP
forwarding and routing. forwarding and routing.
o OAM packets and the user traffic are required to be congruent 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 (i.e. OAM packets are transmitted in-band) and there is a need to
differentiate OAM packets from user-plane ones. Inherent in this differentiate OAM packets from user-plane ones. Inherent in this
requirement is the principle that MPLS-TP OAM be independent of requirement is the principle that MPLS-TP OAM be independent of
any existing control-plane, although it should not preclude use of any existing control-plane, although it should not preclude use of
the control-plane functionality. the control-plane functionality.
4.10.2. Generic Associated Channel 3.7.2. Generic Associated Channel
In order to address the requirement for in-band transmission of MPLS- In order to address the requirement for in-band transmission of MPLS-
TP OAM traffic, MPLS-TP uses a Generic Associated Channel (G-ACh), 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 defined in [G-ACh] for LSP-based OAM traffic. This mechanism is based
on the same concepts as the PWE3 ACH and VCCV mechanisms. However, on the same concepts as the PWE3 ACH and VCCV mechanisms. However,
to address the needs of LSPs as differentiated from PW, the following to address the needs of LSPs as differentiated from PW, the following
concepts were defined for [G-ACh]: concepts were defined for [G-ACh]:
o An Associated Channel Header (ACH), that uses a format similar to o An Associated Channel Header (ACH), that uses a format similar to
the PW Control Word, is a 4-byte header that is added to OAM the PW Control Word, is a 4-byte header that is prepended to OAM
packets. packets.
o A Generic Associated Label (GAL). The GAL is a reserved MPLS label o A Generic Associated Label (GAL). The GAL is a reserved MPLS label
value. The reserved value is 13, and indicates the existence of value (13) that indicates that the packet is an ACH packet and the
the ACH immediately after it. payload follows immediately after the label stack.
4.10.3. MPLS-TP OAM Toolset 3.7.3. MPLS-TP OAM Toolset
To address the functionality that is required of the OAM toolset, the 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 MPLS WG conducted an analysis of the existing IETF and ITU-T OAM
mechanisms and their ability to fulfill the required functionality. mechanisms and their ability to fulfill the required functionality.
The conclusions of this analysis are documented in [OAM Analysis]. The conclusions of this analysis are documented in [OAM Analysis].
The MPLS working group currently plans to use a mixture of OAM The MPLS working group currently plans to use a mixture of OAM
mechanisms that are based on various existing standards, and adapt mechanisms that are based on various existing standards, and adapt
them to the requirements of [MPLS-TP OAM]. Some of the main building them to the requirements of [MPLS-TP OAM]. Some of the main building
blocks of this solution are based on: blocks of this solution are based on:
skipping to change at page 26, line 17 skipping to change at page 20, line 36
o LSP Ping as defined in [LSP Ping] for on-demand connectivity o LSP Ping as defined in [LSP Ping] for on-demand connectivity
verification. verification.
o New protocol packets, using G-ACH, to address different o New protocol packets, using G-ACH, to address different
functionality. functionality.
o Performance measurement protocols that are based on the o Performance measurement protocols that are based on the
functionality that is described in [ITU-T Y.1731]. functionality that is described in [ITU-T Y.1731].
The following sub-sections describe the OAM tools that will be The following sub-sections describe the OAM tools defined for MPLS-TP
defined for MPLS-TP as described in [MPLS-TP OAM FW]. as described in [TP OAM FW].
4.10.3.1. Continuity Check and Connectivity Verification 3.7.3.1. Continuity Check and Connectivity Verification
Continuity Check and Connectivity Verification (CC-V) are OAM Continuity Check and Connectivity Verification are presented in
operations generally used in tandem, and compliment each other. These Section 2.2.5 of this document. As presented there, these tools may
functions are generally run proactively, but may also be used on- be used either proactively or on-demand. When using these tools
demand, either due to bandwidth considerations or for diagnoses of a proactively, they are generally used in tandem.
specific condition. 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.[MPLS-TP OAM FW] highlights 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 function, both
proactively and in on-demand mode, need to be transmitted at regular
rates pre-configured by the operator.
4.10.3.2. Diagnostic Tests For MPLS-TP there are two distinct tools, the proactive tool is
defined in [MPLS-TP CC CV] while the on-demand tool is defined in
[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.
Diagnostic testing is a protocol that allows a network to send [TP OAM FW] highlights, when performing Connectivity Verification,
special test data on a transport path. For example, this could be the need for the CC-V messages to include unique identification of
used as part of bandwidth utilization measurement. the MEG that is being monitored and the MEP that originated the
message.
4.10.3.3. Route Tracing The proactive tool [MPLS-TP CC CV] is based on extensions to BFD (see
Section 3.3) 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
3.4) for the required behavior of MPLS-TP.
3.7.3.2. Route Tracing
[MPLS-TP OAM] defines that there is a need for functionality that [MPLS-TP OAM] defines that there is a need for functionality that
would allow a path end-point to identify the intermediate and end- 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. points of the path. This function would be used in on-demand mode.
Normally, this path will be used for bidirectional PW, LSP, and Normally, this path will be used for bidirectional PW, LSP, and
sections, however, unidirectional paths may be supported only if a sections, however, unidirectional paths may be supported only if a
return path exists. return path exists. The tool for this is based on the LSP Ping (See
Section 3.4) functionality and is described in [OnDemand CV].
4.10.3.4. Lock Instruct 3.7.3.3. Lock Instruct
The Lock Instruct function is used to notify a transport path end- The Lock Instruct function is used to notify a transport path end-
point of an administrative need to disable the transport path. This point of an administrative need to disable the transport path. This
functionality will generally be used in conjunction with some functionality will generally be used in conjunction with some
intrusive OAM function, e.g. Performance measurement, Diagnostic intrusive OAM function, e.g. Performance measurement, Diagnostic
testing, to minimize the side-effect on user data traffic. testing, to minimize the side-effect on user data traffic.
4.10.3.5. Lock Reporting 3.7.3.4. Lock Reporting
Lock Reporting is a function used by an end-point of a path to report 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 to its far-end end-point that a lock condition has been affected on
the path. the path.
4.10.3.6. Alarm Reporting 3.7.3.5. Alarm Reporting
Alarm Reporting is a function used by an intermediate point of a 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 path, that becomes aware of a fault on the path, to report to the
end-points of the path. [MPLS-TP OAM FW] states that this may occur end-points of the path. [TP OAM FW] states that this may occur as a
as a result of a defect condition discovered at a server sub-layer. result of a defect condition discovered at a server sub-layer. This
This generates an Alarm Indication Signal (AIS) that continues until generates an Alarm Indication Signal (AIS) that continues until the
the fault is cleared. The consequent action of this function is fault is cleared. The consequent action of this function is detailed
detailed in [MPLS-TP OAM FW]. in [TP OAM FW].
4.10.3.7. Remote Defect Indication 3.7.3.6. Remote Defect Indication
Remote Defect Indication (RDI) is used proactively by a path end- 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 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 bidirectional connection between them. [MPLS-TP OAM] points out that
this function may be applied to a unidirectional LSP only if there a this function may be applied to a unidirectional LSP only if there a
return path exists. [MPLS-TP OAM FW] points out that this function return path exists. [TP OAM FW] points out that this function is
is associated with the proactive CC-V function. associated with the proactive CC-V function.
4.10.3.8. Client Failure Indication 3.7.3.7. Client Failure Indication
Client Failure Indication (CFI) is defined in [MPLS-TP OAM] to allow Client Failure Indication (CFI) is defined in [MPLS-TP OAM] to allow
the propagation information from one edge of the network to the the propagation information from one edge of the network to the
other. The information concerns a defect to a client, in the case other. The information concerns a defect to a client, in the case
that the client does not support alarm notification. that the client does not support alarm notification.
4.10.3.9. Packet Loss Measurement 3.7.3.8. Packet Loss Measurement
Packet Loss Measurement is a function used to verify the quality of Packet Loss Measurement is a function used to verify the quality of
the service. This function indicates the ratio of packets that are the service. This function indicates the ratio of packets that are
not delivered out of all packets that are transmitted by the path not delivered out of all packets that are transmitted by the path
source. source.
There are two possible ways of determining this measurement: There are two possible ways of determining this measurement:
o Using OAM packets, it is possible to compute the statistics based o Using OAM packets, it is possible to compute the statistics based
on a series of OAM packets. This, however, has the disadvantage of on a series of OAM packets. This, however, has the disadvantage of
being artificial, and may not be representative since part of the being artificial, and may not be representative since part of the
packet loss may be dependent upon packet sizes. packet loss may be dependent upon packet sizes.
o Sending delimiting messages for the start and end of a measurement o Sending delimiting messages for the start and end of a measurement
period during which the source and sink of the path count the period during which the source and sink of the path count the
packets transmitted and received. After the end delimiter, the packets transmitted and received. After the end delimiter, the
ratio would be calculated by the path OAM entity. ratio would be calculated by the path OAM entity.
4.10.3.10. Packet Delay Measurement 3.7.3.9. Packet Delay Measurement
Packet Delay Measurement is a function that is used to measure one- 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 way or two-way delay of a packet transmission between a pair of the
end-points of a path (PW, LSP, or Section). Where: end-points of a path (PW, LSP, or Section). Where:
o One-way packet delay is the time elapsed from the start of 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 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 the reception of the last bit of that packet by the destination
node. node.
o Two-way packet delay is the time elapsed from the start of 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 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 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 same source node, when the loopback is performed at the packet's
destination node. destination node.
Similarly to the packet loss measurement this could be performed in Similarly to the packet loss measurement this could be performed in
either of the two ways outlined above. either of the two ways outlined above.
4.11. Summary of OAM Functions 3.8. Summary of OAM Functions
Table 3 summarizes the OAM functions that are supported in each of Table 3 summarizes the OAM functions that are supported in each of
the standards that were analyzed in this section. the standards that were analyzed in this section.
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
| Standard |Continu|Connecti|Path |Defect |Perform|Other | | Standard |Continu|Connecti|Path |Defect |Perform|Other |
| |ity |vity |Discover|Indications|ance |Function| | |ity |vity |Discover|Indications|ance |Function|
| |Check |Verifica|y | |Monitor|s | | |Check |Verifica|y | |Monitor|s |
| | |tion | | |ing | | | | |tion | | |ing | |
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
|ICMP Ping | |Echo |Tracerou| | | | |ICMP Ping | |Echo | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|Traceroute | | |Tracerou| | | |
| | | |te | | | | | | | |te | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|BFD |BFD |BFD | | | | | |BFD |BFD |BFD | | | | |
| |Control|Echo | | | | | | |Control|Echo | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|LSP Ping | |"Ping" |"Tracero| | | | |LSP Ping | |"Ping" |"Tracero| | | |
| | |mode |ute" | | | | | | |mode |ute" | | | |
| | | |mode | | | | | | | |mode | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|PW VCCV | |VCCV | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IPPM | | | | |-Delay | | |IPPM | | | | |-Delay | |
| | | | | | measur| | | | | | | | measur| |
| | | | | | ement | | | | | | | | ement | |
| | | | | |-Packet| | | | | | | |-Packet| |
| | | | | | loss | | | | | | | | loss | |
| | | | | | measur| | | | | | | | measur| |
| | | | | | ement | | | | | | | | ement | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|ITU-T |-CV | | | | | | |MPLS-TP |CC |CV/pro- |Route |-Alarm |-LM |-Diagnos|
|Y.1711 |-FFD | | | | | | |OAM | |active |Tracing | Reporting |-DM | tic Tes|
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + | | |or on- | |-Client | | t |
|ITU-T |ETH-CC |ETH-LB |ETH-LT |-ETH-RDI |-ETH-LM|-ETH-LCK| | | |demand | | Failure | |-Lock |
|Y.1731 | | | |-ETH-AIS |-ETH-DM|-ETH-APS|
| | | | | | |-ETH-TST|
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IEEE |CC |Loopback|Linktrac| | | |
|802.1ag | | |e | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IEEE | |Remote | |-Remote | | |
|802.3ah | |Loopback| | Failure | | |
| | | | | Indication| | |
| | | | |-Link | | |
| | | | | Monitoring| | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|MPLS-TP |CC |CV |Route |-Alarm |-LM |-Diagnos|
|OAM | | |Tracing | Reporting |-DM | tic Tes|
| | | | |-Client | | s |
| | | | | Failure | |-Lock |
| | | | | Indication| | | | | | | | Indication| | |
| | | | |-Remote | | | | | | | |-Remote | | |
| | | | | Defect | | | | | | | | Defect | | |
| | | | | Indication| | | | | | | | Indication| | |
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
Table 3 Summary of OAM Functions Table 3 Summary of OAM Functions
4.12. Summary of Continuity Check Mechanisms 4. Security Considerations
A key element in some of the OAM standards that are analyzed in this
document is the continuity check. It is thus interesting to present a
more detailed comparison of the connectivity check mechanisms defined
in OAM standards. Table 4 can be viewed as an extension of Table 3,
but is presented separately for convenience. The table compares the
OAM standards that support a continuity check. MPLS-TP is not
included in the comparison, as the continuity check mechanism in
MPLS-TP has not yet been defined.
The "Tx Interval" column in the table specifies the period between
two consequent message transmissions, while the "Source Identifier"
column specifies the name of the field in the OAM packet that is used
as the identifier of the transmitter. The "Error Codes" column
specifies the possible error codes when the unidirectional
connectivity check detects a failure.
+-----------+-------+--------+---+--------+------------------------+
| |Mechani|Tx |UC/|Source | Error |
| |sm |Interval|MC |Identifi| Codes |
| | | | |er | |
+-----------+-------+--------+---+--------+------------------------+
|BFD |BFD |Negotiat|UC |My Discr| Control Detection Time |
| |Control|ed durin| |iminator| Expired |
| | |g sessio| | | |
| | |n | | | |
+ --------- + ----- + ------ + - + ------ + ---------------------- +
|ITU-T |CV |CV: 1s |UC |TTSI |-Loss of CV (LOCV) |
|Y.1711 |FFD |FFD: par| | |-TTSI Mismatch |
| | |ameter, | | |-TTSI Mismerge |
| | |default:| | |-Excess |
| | |50 ms | | | |
+ --------- + ----- + ------ + - + ------ + ---------------------- +
|ITU-T |CC |7 possib|UC/|MEP ID |-Loss of Continuity(LOC)|
|Y.1731 / | |le perio|MC | |-Unexpected MEG level |
|IEEE | |ds: | | |-Mismerge |
|802.1ag | |3 1/3 ms| | |-Unexpected MEP |
| | |10 ms | | |-Unexpected period |
| | |100 ms | | | |
| | |1 s | | | |
| | |10 s | | | |
| | |1 min | | | |
| | |10 min | | | |
+-----------+-------+--------+---+--------+------------------------+
Table 4 Summary of OAM Terms
5. Security Considerations
There are no security implications imposed by this document. 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.
6. IANA Considerations 5. IANA Considerations
There are no new IANA considerations implied by this document. There are no new IANA considerations implied by this document.
7. Acknowledgments 6. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
8. References 7. References
8.1. Normative References 7.1. Normative References
[LSP Ping] Kompella, K., Swallow, G., "Detecting Multi-Protocol [LSP Ping] Kompella, K., Swallow, G., "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379, Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006. February 2006.
[MPLS OAM] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and [MPLS OAM] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and
Matsushima, S., "Operations and Management (OAM) Matsushima, S., "Operations and Management (OAM)
Requirements for Multi-Protocol Label Switched (MPLS) Requirements for Multi-Protocol Label Switched (MPLS)
Networks", RFC 4377, February 2006. Networks", RFC 4377, February 2006.
[MPLS OAM FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol [MPLS OAM FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol
Label Switching (MPLS) Operations and Management Label Switching (MPLS) Operations and Management
(OAM)", RFC 4378, February 2006. (OAM)", RFC 4378, February 2006.
[MPLS OAM P2MP] Yasukawa, S., Farrel, A., King, D., and Nadeau, T.,
"Operations and Management (OAM) Requirements for
Point-to-Multipoint MPLS Networks", RFC 4687,
September 2006.
[OAM Label] Ohta, H., "Assignment of the 'OAM Alert Label' for [OAM Label] Ohta, H., "Assignment of the 'OAM Alert Label' for
Multiprotocol Label Switching Architecture (MPLS) Multiprotocol Label Switching Architecture (MPLS)
Operation and Maintenance (OAM) Functions", RFC 3429, Operation and Maintenance (OAM) Functions", RFC 3429,
November 2002. November 2002.
[MPLS-TP OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for [MPLS-TP OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for
OAM in MPLS Transport Networks", RFC 5860, May 2010. OAM in MPLS Transport Networks", RFC 5860, May 2010.
[G-ACh] Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic [G-ACh] Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic
Associated Channel", RFC 5586, June 2009. Associated Channel", RFC 5586, June 2009.
skipping to change at page 32, line 26 skipping to change at page 25, line 26
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word
for Use over an MPLS PSN", RFC 4385, February 2006. for Use over an MPLS PSN", RFC 4385, February 2006.
[ICMPv4] Postel, J., "Internet Control Message Protocol", STD 5, [ICMPv4] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981. RFC 792, September 1981.
[ICMPv6] Conta, A., Deering, S., and M. Gupta, "Internet Control [ICMPv6] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006. Version 6 (IPv6) Specification", RFC 4443, March 2006.
[TCPIP Tools] Kessler, G., Shepard, S., "A Primer On Internet and
TCP/IP Tools and Utilities", RFC 2151, June 1997.
[IPPM FW] Paxson, V., Almes, G., Mahdavi, J., and Mathis, M., [IPPM FW] Paxson, V., Almes, G., Mahdavi, J., and Mathis, M.,
"Framework for IP Performance Metrics", RFC 2330, May "Framework for IP Performance Metrics", RFC 2330, May
1998. 1998.
[IPPM Con] Mahdavi, J., Paxson, V., "IPPM Metrics for Measuring [IPPM Con] Mahdavi, J., Paxson, V., "IPPM Metrics for Measuring
Connectivity", RFC 2678, September 1999. Connectivity", RFC 2678, September 1999.
[IPPM 1DM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way [IPPM 1DM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
Delay Metric for IPPM", RFC 2679, September 1999. Delay Metric for IPPM", RFC 2679, September 1999.
skipping to change at page 33, line 28 skipping to change at page 26, line 32
[BFD LSP] Aggarwal, R., Kompella, K., Nadeau, T., and Swallow, [BFD LSP] Aggarwal, R., Kompella, K., Nadeau, T., and Swallow,
G., "Bidirectional Forwarding Detection (BFD) for MPLS G., "Bidirectional Forwarding Detection (BFD) for MPLS
Label Switched Paths (LSPs)", RFC 5884, June 2010. Label Switched Paths (LSPs)", RFC 5884, June 2010.
[BFD VCCV] Nadeau, T., Pignataro, C., "Bidirectional Forwarding [BFD VCCV] Nadeau, T., Pignataro, C., "Bidirectional Forwarding
Detection (BFD) for the Pseudowire Virtual Circuit Detection (BFD) for the Pseudowire Virtual Circuit
Connectivity Verification (VCCV)", RFC 5885, June Connectivity Verification (VCCV)", RFC 5885, June
2010. 2010.
[IEEE 802.1ag]"Connectivity Fault Management", December 2007. [TP OAM FW] Busi, I., Allan, D., "Operations, Administration and
Maintenance Framework for MPLS-based Transport
Networks ", RFC 6371, September 2011.
[ITU-T Y.1731]"OAM Functions and Mechanisms for Ethernet-based [MPLS-TP CC CV] Allan, D., Swallow, G., Drake, J., "Proactive
Networks", February 2008. Connectivity Verification, Continuity Check and Remote
Defect indication for MPLS Transport Profile", RFC
6428, November 2011.
[ITU-T Y.1711]"Operation & Maintenance mechanism for MPLS networks", [OnDemand CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS
February 2004. On-Demand Connectivity Verification and Route
Tracing", RFC 6426, November 2011.
[IEEE 802.3ah]"Media Access Control Parameters, Physical Layers, and [MPLS LM DM] Frost, D., Bryant, S., "Packet Loss and Delay
Management Parameters for Subscriber Access Networks", Measurement for MPLS Networks", RFC 6374, September
clause 57, September 2004. 2011.
8.2. Informative References [TP LM DM] Frost, D., Bryant, S., "A Packet Loss and Delay
Measurement Profile for MPLS-Based Transport
Networks", RFC 6375, September 2011.
[OAM Soup] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu, [MPLS-TP Fault] Swallow, G., Fulignoli, A., Vigoureux, M., Boutros,
D., Mansfield, S., " Guidelines for the use of the OAM S., "MPLS Fault Management Operations, Administration,
acronym in the IETF ", work-in-progress, draft-ietf- and Maintenance (OAM)", RFC 6427, November 2011.
opsawg-mpls-tp-oam-def, September, 2010.
[OAM Analysis] Sprecher, N., Bellagamba, E., Weingarten, Y., "OAM [TP Lock Loop] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux,
functions in MPLS based transport network", work-in- M., Dai, X., "MPLS Transport Profile Lock Instruct and
progress, draft-ietf-mpls-tp-oam-analysis, January, Loopback Functions", RFC 6435, November 2011.
2011.
[MPLS-TP OAM FW] Busi, I., Niven-Jenkins, B., Allan, D., "Operations, 7.2. Informative References
Administration and Maintenance Framework for MPLS-
based Transport Networks ", work-in-progress, draft- [OAM Def] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu,
ietf-mpls-tp-oam-framework, February, 2011. D., Mansfield, S., "Guidelines for the use of the OAM
acronym in the IETF ", RFC 6291, June 2011.
[OAM Analysis]Sprecher, N., Fang, L., "An Overview of the OAM Tool
Set for MPLS based Transport Networks", work-in-
progress, draft-ietf-mpls-tp-oam-analysis, March 2012.
[MPLS-TP Term]Van Helvoort, H., Andersson, L., Sprecher, N., "A [MPLS-TP Term]Van Helvoort, H., Andersson, L., Sprecher, N., "A
Thesaurus for the Terminology used in Multiprotocol Thesaurus for the Terminology used in Multiprotocol
Label Switching Transport Profile (MPLS-TP) Label Switching Transport Profile (MPLS-TP)
drafts/RFCs and ITU-T's Transport Network drafts/RFCs and ITU-T's Transport Network
Recommendations", work-in-progress, draft-ietf-mpls- Recommendations", work-in-progress, draft-ietf-mpls-
tp-rosetta-stone, November, 2010. tp-rosetta-stone, January 2012.
[MPLS-TP Ping BFD] Bahadur, N., Aggarwal, R., Ward, D., Nadeau, T., [IEEE 802.1ag]"Connectivity Fault Management", December 2007.
Sprecher, N., Weingarten, Y., "LSP-Ping and BFD
encapsulation over ACH", draft-ietf-mpls-tp-lsp-ping-
bfd-procedures, work-in-progress, August, 2010.
[P2MP Ping] Saxena, S., Farrel, A. , Yasukawa, S., "Detecting Data [ITU-T Y.1731]"OAM Functions and Mechanisms for Ethernet-based
Plane Failures in Point-to-Multipoint Multiprotocol Networks", February 2008.
Label Switching (MPLS) - Extensions to LSP Ping",
work-in-progress, draft-ietf-mpls-p2mp-lsp-ping, [ITU-T Y.1711]"Operation & Maintenance mechanism for MPLS networks",
March, 2011. February 2004.
[IEEE 802.3ah]"Media Access Control Parameters, Physical Layers, and
Management Parameters for Subscriber Access Networks",
clause 57, September 2004.
[ITU-T G.806] "Characteristics of transport equipment - Description [ITU-T G.806] "Characteristics of transport equipment - Description
methodology and generic functionality", January 2009. methodology and generic functionality", January, 2009.
Authors' Addresses Authors' Addresses
Tal Mizrahi Tal Mizrahi
Marvell Marvell
6 Hamada St. 6 Hamada St.
Yokneam, 20692 Yokneam, 20692
Israel Israel
Email: talmi@marvell.com Email: talmi@marvell.com
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