draft-ietf-opsawg-oam-overview-00.txt   draft-ietf-opsawg-oam-overview-01.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 January 17, 2010 Intended status: Informational July 12, 2010
Expires: July 2010 Expires: January 2011
An Overview of An Overview of
Operations, Administration, and Maintenance (OAM) Mechanisms Operations, Administration, and Maintenance (OAM) Mechanisms
draft-ietf-opsawg-oam-overview-00.txt draft-ietf-opsawg-oam-overview-01.txt
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Abstract Abstract
Operations, Administration, and Maintenance (OAM) is a general term Operations, Administration, and Maintenance (OAM) is a general term
that refers to detecting and reporting link failures. OAM mechanisms that refers to detecting and reporting link failures. OAM mechanisms
have been defined for various layers in the protocol stack, and are have been defined for various layers in the protocol stack, and are
used with a variety of protocols. used with a variety of protocols.
This document presents an overview of the OAM mechanisms that have This document presents an overview of the OAM mechanisms that have
been defined and are currently being defined by the IETF, as well as 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 a comparison to other OAM mechanisms that have been defined by the
IEEE and ITU-T. IEEE and ITU-T.
Table of Contents Table of Contents
1. Introduction................................................3 1. Introduction................................................4
2. Conventions used in this document............................5 2. Conventions used in this document............................8
3. Basic Terminology...........................................5 3. Basic Terminology...........................................8
3.1. Abbreviations..........................................5 3.1. Abbreviations..........................................8
3.2. Terminology used in OAM Standards.......................6 3.2. Terminology used in OAM Standards.......................9
3.2.1. General Terms......................................6 3.2.1. General Terms......................................9
3.2.2. OAM Maintenance Entities...........................7 3.2.2. OAM Maintenance Entities...........................9
3.2.3. OAM Maintenance Points.............................7 3.2.3. OAM Maintenance Points............................10
3.2.4. OAM Link Failures..................................7 3.2.4. OAM Link Failures.................................10
3.2.5. Summary of OAM Terms used in the Standards..........7 3.2.5. Summary of OAM Terms used in the Standards.........10
4. OAM Functions...............................................9 4. OAM Functions..............................................12
4.1. ICMP Ping..............................................9 4.1. ICMP Ping.............................................12
4.2. Bidirectional Forwarding Detection (BFD)................9 4.2. Bidirectional Forwarding Detection (BFD)...............12
4.2.1. Overview..........................................9 4.2.1. Overview.........................................12
4.2.2. BFD Control........................................9 4.2.2. BFD Control.......................................12
4.2.3. BFD Echo.........................................10 4.2.3. BFD Echo.........................................13
4.3. LSP Ping..............................................10 4.3. LSP Ping..............................................13
4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV)...10 4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV)...13
4.5. ITU-T Y.1711..........................................10 4.5. IP Performance Metrics (IPPM)..........................14
4.5.1. Overview.........................................10 4.5.1. Overview.........................................14
4.5.2. Connectivity Verification (CV)....................11 4.5.2. OWAMP/TWAMP Control...............................14
4.5.3. Fast Failure Detection (FFD)......................11 4.5.3. OWAMP/TWAMP Test..................................14
4.5.4. Forward Defect Indication (FDI)...................11 4.6. ITU-T Y.1711..........................................14
4.5.5. Backward Defect Indication (BDI)..................12 4.6.1. Overview.........................................14
4.6. ITU-T Y.1731..........................................12 4.6.2. Connectivity Verification (CV)....................15
4.6.1. Overview.........................................12 4.6.3. Fast Failure Detection (FFD)......................15
4.6.2. ETH-CC...........................................12 4.6.4. Forward Defect Indication (FDI)...................15
4.6.3. ETH-LB...........................................13 4.6.5. Backward Defect Indication (BDI)..................15
4.6.4. ETH-TST..........................................13
4.6.5. ETH-LT...........................................13 4.7. ITU-T Y.1731..........................................16
4.6.6. ETH-AIS..........................................13 4.7.1. Overview.........................................16
4.6.7. ETH-LCK..........................................14 4.7.2. ETH-CC...........................................16
4.6.8. ETH-RDI..........................................14 4.7.3. ETH-LB...........................................17
4.6.9. ETH-APS..........................................14 4.7.4. ETH-TST..........................................17
4.6.10. ETH-LM..........................................14 4.7.5. ETH-LT...........................................17
4.6.11. ETH-DM..........................................15 4.7.6. ETH-AIS..........................................17
4.7. IEEE 802.1ag..........................................15 4.7.7. ETH-LCK..........................................17
4.7.1. Overview.........................................15 4.7.8. ETH-RDI..........................................18
4.7.2. Continuity Check..................................16 4.7.9. ETH-APS..........................................18
4.7.3. Loopback.........................................16 4.7.10. ETH-LM..........................................18
4.7.4. Linktrace........................................16 4.7.11. ETH-DM..........................................18
4.8. IEEE 802.3ah..........................................16 4.8. IEEE 802.1ag..........................................19
4.8.1. Overview.........................................16 4.8.1. Overview.........................................19
4.8.2. Remote Failure Indication.........................16 4.8.2. Continuity Check..................................19
4.8.3. Remote Loopback...................................16 4.8.3. Loopback.........................................19
4.8.4. Link Monitoring...................................16 4.8.4. Linktrace........................................20
4.9. MPLS-TP OAM...........................................16 4.9. IEEE 802.3ah..........................................20
4.9.1. Overview.........................................16 4.9.1. Overview.........................................20
4.9.2. Continuity Checks.................................17 4.9.2. Remote Failure Indication.........................20
4.9.3. Connectivity Verification.........................17 4.9.3. Remote Loopback...................................20
4.9.4. Diagnostic Tests..................................17 4.9.4. Link Monitoring...................................20
4.9.5. Route Tracing.....................................17 4.10. MPLS-TP OAM..........................................20
4.9.6. Lock Instruct.....................................17 4.10.1. Overview........................................20
4.9.7. Lock Reporting....................................17 4.10.2. Continuity Checks................................21
4.9.8. Alarm Reporting...................................17 4.10.3. Connectivity Verification........................21
4.9.9. Remote Defect Indication..........................18 4.10.4. Diagnostic Tests.................................21
4.9.10. Client Failure Indication........................18 4.10.5. Route Tracing....................................22
4.9.11. Packet Loss Measurement..........................18 4.10.6. Lock Instruct....................................22
4.9.12. Packet Delay Measurement.........................18 4.10.7. Lock Reporting...................................22
4.10. Summary of OAM Functions..............................18 4.10.8. Alarm Reporting..................................22
4.11. Summary of Unidirectional Connectivity Check Mechanisms19 4.10.9. Remote Defect Indication.........................22
5. Security Considerations.....................................20 4.10.10. Client Failure Indication.......................22
6. IANA Considerations........................................20 4.10.11. Packet Loss Measurement.........................22
7. Acknowledgments............................................20 4.10.12. Packet Delay Measurement........................22
8. References.................................................21 4.11. Summary of OAM Functions..............................22
8.1. Normative References...................................21 4.12. Summary of Unidirectional Connectivity Check Mechanisms24
8.2. Informative References.................................21 5. Security Considerations.....................................25
6. IANA Considerations........................................25
7. Acknowledgments............................................25
8. References.................................................25
8.1. Normative References...................................25
8.2. Informative References.................................28
1. Introduction 1. Introduction
OAM is a general term that refers to detecting and reporting link OAM is a general term that refers to detecting and reporting link
failures and defects. The term OAM has been used over the years in failures and defects. The term OAM has been used over the years in
several different contexts, as discussed in [OAM Soup]. In the several different contexts, as discussed in [OAM Soup]. In the
context of this document OAM refers to Operations, Administration, context of this document OAM refers to Operations, Administration,
and Maintenance. OAM was originally used in the world of telephony, and Maintenance, i.e., this document refers to OAM in the context of
and has been adopted in packet based networks. OAM mechanisms are monitoring communication links. Other aspects associated with the OAM
used in various layers in the protocol stack, and are applied to a acronym, such as management, are not described in this document.
variety of different protocols.
OAM was originally used in the world of telephony, and has been
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 IETF has defined OAM for several protocols, and is currently
working on defining several new OAM protocols. These protocols are working on defining several new OAM protocols. A summary of these
listed below. protocols, old and new, is listed below:
o MPLS LSP Ping, as defined in [LSP Ping] is an OAM mechanism for o MPLS LSP Ping, as defined in [LSP Ping] is an OAM mechanism for
point to point MPLS LSPs. The IETF is currently working on an point to point MPLS LSPs. The IETF is currently working on an
extension to the LSP Ping for point to multipoint MPLS - [P2MP extension to the LSP Ping for point to multipoint MPLS - [P2MP
Ping]. Ping].
o Virtual Circuit Connectivity Check (VCCV) for Pseudowires, as o Virtual Circuit Connectivity Check (VCCV) for Pseudowires, as
defined in [VCCV]. defined in [VCCV].
o ICMP Echo request, also known as Ping, as defined in [ICMPv4], and o 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 typically associated with OAM, but failure diagnosis, and is not traditionally associated with OAM,
it is presented in this document for the sake of completeness, 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 since both LSP Ping and VCCV are to some extent based on ICMP
Ping. Ping.
o Bidirectional Forwarding Detection (BFD) is a family of standards o Bidirectional Forwarding Detection (BFD) is a family of standards
that are currently being defined by the IETF. BFD is intended to that are currently being defined by the IETF. BFD is intended to
be a generic OAM mechanism that can be used with various be a generic OAM mechanism that can be used with various
encapsulation types, and in various medium types. encapsulation types, and in various medium types.
o OAM for MPLS-TP is currently being defined in the MPLS workgroup. o OAM for MPLS-TP is currently being defined in the MPLS working
group.
o 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.
While performance measurement is not directly related to link
failures, it is often associated with OAM. Alternative protocols
for performance measurement are defined, for example, in MPLS-TP
OAM [MPLS-TP OAM], and in Ethernet OAM [ITU-T Y.1731].
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. These various
mechanisms defined by the three standard organizations are often mechanisms defined by the three standard organizations are often
tightly coupled, and have had a mutual effect on each other. For tightly coupled, and have had a mutual effect on each other. For
example, the emerging MPLS-TP OAM is in many ways based on [ITU-T example, the emerging MPLS-TP OAM is in many ways based on [ITU-T
Y.1731]. The ITU-T and IETF have both defined OAM mechanisms for MPLS Y.1731]. The ITU-T and IETF have both defined OAM mechanisms for MPLS
LSPs, [ITU-T Y.1711] and [LSP Ping]. The following OAM standards by LSPs, [ITU-T Y.1711] and [LSP Ping]. The following OAM standards by
the IEEE and ITU-T are to some extent linked to IETF OAM mechanisms the IEEE and ITU-T are to some extent linked to IETF OAM mechanisms
listed above, and are also discussed in this document: listed above, and are also discussed in this document:
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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 This document summarizes the OAM mechanisms defined in the standards
above. The focus is on OAM mechanisms defined by the IETF, compared above. The focus is on OAM mechanisms defined by the IETF, compared
with the relevant OAM mechanisms defined by the ITU-T and IEEE. We with the relevant OAM mechanisms defined by the ITU-T and IEEE. We
first present a comparison of the terminology used in various OAM first present a comparison of the terminology used in various OAM
standards, and then summarize the OAM functions that each OAM standards, and then summarize the OAM functions that each OAM
standard provides. standard provides.
Table 1 summarizes the OAM standards discussed in this document.
+-----------+--------------------------------------+---------------+
| | Title |Standard |
+-----------+--------------------------------------+---------------+
|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 | |
+-----------+--------------------------------------+---------------+
|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] |
|MPLS OAM | for MPLS networks | |
| +--------------------------------------+---------------+
| | Assignment of the 'OAM Alert Label' | RFC 3429 |
| | for Multiprotocol Label Switching | |
| | Architecture (MPLS) Operation and | |
| | Maintenance (OAM) Functions | |
+-----------+--------------------------------------+---------------+
|ITU-T | OAM Functions and Mechanisms for |[ITU-T Y.1731] |
|Ethernet | Ethernet-based Networks | |
|OAM | | |
+-----------+--------------------------------------+---------------+
|MPLS-TP | Requirements for OAM in MPLS | RFC 5860 |
|OAM +--------------------------------------+---------------+
| | MPLS Generic Associated Channel | RFC 5586 |
+-----------+--------------------------------------+---------------+
|IEEE | Connectivity Fault Management |[IEEE 802.1ag] |
|CFM | | |
+-----------+--------------------------------------+---------------+
|IEEE | Media Access Control Parameters, |[IEEE 802.3ah] |
|802.3 | Physical Layers, and Management | |
|link level | Parameters for Subscriber Access | |
|OAM | Networks | |
+-----------+--------------------------------------+---------------+
Table 1 Summary of OAM Standards
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [KEYWORDS]. document are to be interpreted as described in [KEYWORDS].
3. Basic Terminology 3. Basic Terminology
3.1. Abbreviations 3.1. Abbreviations
skipping to change at page 7, line 48 skipping to change at page 10, line 44
term Fault refers to an inability to perform a required action, e.g., term Fault refers to an inability to perform a required action, e.g.,
an unsuccessful attempt to deliver a packet. The term Defect refers an unsuccessful attempt to deliver a packet. The term Defect refers
to an interruption in the normal operation, such as a consecutive to an interruption in the normal operation, such as a consecutive
period of time where no packets are delivered successfully. The term period of time where no packets are delivered successfully. The term
Failure refers to the termination of the required function. While a Failure refers to the termination of the required function. While a
Defect typically refers to a limited period of time, a failure refers Defect typically refers to a limited period of time, a failure refers
to a long period of time. to a long period of time.
3.2.5. Summary of OAM Terms used in the Standards 3.2.5. Summary of OAM Terms used in the Standards
Table 1 provides a comparison of the terminology used in different Table 2 provides a comparison of the terminology used in different
OAM standards. OAM standards.
+-----------+-------------+-----------+----------------------------+ +-----------+-------------+-----------+----------------------------+
| |Maintenance |Maintenance|Link Failure Terminology | | |Maintenance |Maintenance|Link Failure Terminology |
| |Point |Entity | | | |Point |Entity | |
| |Terminology |Terminology| | | |Terminology |Terminology| |
+-----------+-------------+-----------+----------------------------+ +-----------+-------------+-----------+----------------------------+
|ICMPv4 Ping|-Host | | | |ICMPv4 Ping|-Host | | |
| |-Gateway | | | | |-Gateway | | |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
skipping to change at page 8, line 25 skipping to change at page 11, line 20
|BFD | System | Session |-Failure | |BFD | System | Session |-Failure |
| | | |-Session is declared down | | | | |-Session is declared down |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|LSP Ping | LSR | LSP |-Failure | |LSP Ping | LSR | LSP |-Failure |
| | | |-Fault = typically a local | | | | |-Fault = typically a local |
| | | | isolated failure | | | | | isolated failure |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|PW VCCV |-PE | PW |-Failure | |PW VCCV |-PE | PW |-Failure |
| |-LCCE | |-Fault | | |-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 | |ITU-T | LSR | LSP |-Fault, Defect, Failure: as |
|Y.1711 | | | defined in [ITU-T G.806] | |Y.1711 | | | defined in [ITU-T G.806] |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|ITU-T |-MEP | ME |-Fault, Defect, Failure: as | |ITU-T |-MEP | ME |-Fault, Defect, Failure: as |
|Y.1731 |-MIP | | defined in [ITU-T G.806] | |Y.1731 |-MIP | | defined in [ITU-T G.806] |
| | | | | | | | | |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|MPLS-TP |-End Point |-LSP |-Fault, Defect, Failure: as | |MPLS-TP |-End Point |-LSP |-Fault, Defect, Failure: as |
|OAM |-Intermediate|-PW | defined in [ITU-T G.806] | |OAM |-Intermediate|-PW | defined in [ITU-T G.806] |
| |Point |-Section | | | |Point |-Section | |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|IEEE |-MEP | ME |-Failure | |IEEE |-MEP | ME |-Failure |
|802.1ag |-MIP | |-Fault | |802.1ag |-MIP | |-Fault |
| |-MP | |-Defect | | |-MP | |-Defect |
+ --------- + ----------- + --------- + -------------------------- + + --------- + ----------- + --------- + -------------------------- +
|IEEE | DTE | Link |-Failure | |IEEE | DTE | Link |-Failure |
|802.3ah | | |-Fault | |802.3ah | | |-Fault |
+-----------+-------------+-----------+----------------------------+ +-----------+-------------+-----------+----------------------------+
Table 1 Summary of OAM Terms Table 2 Summary of OAM Terms
4. OAM Functions 4. OAM Functions
4.1. ICMP Ping 4.1. ICMP Ping
ICMP provides a bidirectional connectivity check for the Internet ICMP provides a bidirectional connectivity check for the Internet
Protocol. The originator transmits an echo request packet, and the Protocol. The originator transmits an echo request packet, and the
receiver replies with an echo reply. ICMP ping is defined in two 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.
4.2. Bidirectional Forwarding Detection (BFD) 4.2. Bidirectional Forwarding Detection (BFD)
4.2.1. Overview 4.2.1. 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],
currently being defined by the IETF [BFD], defines a generic OAM defined by the IETF BFD working group, is a generic OAM mechanism
mechanism that can be run over various encapsulating protocols, and that can be deployed over various encapsulating protocols, and in
in various medium types. The IETF is working on defining variants of various medium types. The IETF has defined variants of the protocol
the protocol for IP, for MPLS LSPs, 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
group (e.g. [MPLS-TP Ping BFD]).
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 4.2.2. BFD Control
BFD supports a unidirectional connectivity check, using BFD control BFD supports a unidirectional connectivity check, using BFD control
packets. BFD control packets are be sent in one of two modes: packets. BFD control packets are be sent in one of two modes:
o Asynchronous mode: in this mode BFD control packets are sent o Asynchronous mode: in this mode BFD control packets are sent
skipping to change at page 10, line 20 skipping to change at page 13, line 24
Discriminator, respectively. Discriminator, respectively.
4.2.3. BFD Echo 4.2.3. BFD Echo
The echo function is a bidirectional connectivity check. A BFD echo The echo function is a bidirectional connectivity check. 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 4.3. LSP Ping
The IETF defined an OAM mechanisms for MPLS LSPs in [LSP Ping]. LSP The IETF MPLS working group has defined OAM for MPLS LSPs. The
ping is used to detect data plain failures in MPLS LSPs. The requirements and framework of this effort was defined in [MPLS OAM
transmitting LSR sends an echo request to a remote LSR, and in turn FW] and [MPLS OAM], respectively. The corresponding OAM mechanism
receives an echo reply. LSP ping is used in one of two modes: that was defined in this context is LSP Ping [LSP Ping]. LSP ping is
used to detect data plain failures in MPLS LSPs. The transmitting LSR
sends an echo request to a remote LSR, and in turn receives an echo
reply. LSP ping is 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 LSRs.
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. localization.
4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV) 4.4. PWE3 Virtual Circuit Connectivity Verification (VCCV)
VCCV, as defined in [VCCV], maintains the connectivity status of a VCCV, as defined in [VCCV], maintains the connectivity status of a
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VCCV supports two possible Connectivity Verification (CV) types, VCCV supports two possible Connectivity Verification (CV) types,
i.e., two modes of operation: i.e., two modes of operation:
o ICMP Ping: In this mode the CV is performed using an ICMP ping o ICMP Ping: In this mode the CV is performed using an ICMP ping
packet format, as defined in [ICMPv4] or [ICMPv6]. packet format, as defined in [ICMPv4] or [ICMPv6].
o LSP Ping: In this mode the LSP Ping packet format, as defined in o LSP Ping: In this mode the LSP Ping packet format, as defined in
[LSP Ping] is used for CV. [LSP Ping] is used for CV.
4.5. ITU-T Y.1711 4.5. IP Performance Metrics (IPPM)
4.5.1. Overview 4.5.1. Overview
The IPPM working group [IPPM FW] in the IETF defines common criteria
and metrics for measuring performance of IP traffic. Some of the key
RFCs published by this working group have defined metrics for
measuring connectivity [rfc2678], delay [RFC2679, RFC 2681], and
packet loss [RFC2681].
The IPPM working group has defined not only metrics for performance
measurement, but also protocols that define how the measurement is
carried out. The One-way Active Measurement Protocol [OWAMP] and the
Two-Way Active Measurement Protocol [TWAMP] define a method and
protocol for measuring delay and packet loss in IP networks.
OWAMP and TWAMP use two separate protocols: a Control plane protocol,
and a Test plane protocol.
4.5.2. OWAMP/TWAMP Control
Each of these standards defines a Control protocol. This protocol is
layered over TCP, and is used to initiate measurement sessions, and
to communicate their results.
4.5.3. OWAMP/TWAMP Test
The Test protocol is layered over UDP, and is used to measure delay
and packet loss between the session endpoints. The Test session is
initiated by a Request/Response negotiation, followed by a set of
active test packets that are used for the measurement.
4.6. ITU-T Y.1711
4.6.1. Overview
As mentioned above (4.3.), the IETF defined LSP Ping as an OAM 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 mechanism for MPLS. The ITU-T has also defined an OAM protocol for
MPLS, defined in [ITU-T Y.1711]. The standard defines mechanisms for MPLS, defined in [ITU-T Y.1711]. The standard defines mechanisms for
connectivity verification and fast failure detection, as well as connectivity verification and fast failure detection, as well as
mechanism for reporting defects that have been identified in an LSP. mechanism for reporting defects that have been identified in an LSP.
4.5.2. Connectivity Verification (CV) 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 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 frames are sent proactively at a rate of 1 per second. Each frame
contains the Trail-Termination Source Identifier (TTSI), indicating contains the Trail-Termination Source Identifier (TTSI), indicating
the identity of the transmitting LSR. the identity of the transmitting LSR.
The CV function can detect any of the following defect conditions. The CV function can detect any of the following defect conditions.
o Loss of Connectivity Verification (LOCV): A loss of connectivity o Loss of Connectivity Verification (LOCV): A loss of connectivity
is detected when no CV OAM packets are received in a period of 3 is detected when no CV OAM packets are received in a period of 3
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o TTSI Mismatch: A TTSI mismatch is detected when a CV frame with an o TTSI Mismatch: A TTSI mismatch is detected when a CV frame with an
unexpected TTSI is received. unexpected TTSI is received.
o TTSI Mismerge: A TTSI mismerge is detected when the CV frames o TTSI Mismerge: A TTSI mismerge is detected when the CV frames
received in a given LSP contain some frame with an expected TTSI, received in a given LSP contain some frame with an expected TTSI,
and some frames with an unexpected TTSI. and some frames with an unexpected TTSI.
o Excess: An excess is detected when at least 5 CV frames are o Excess: An excess is detected when at least 5 CV frames are
received during a period of 3 consecutive transmission periods. received during a period of 3 consecutive transmission periods.
4.5.3. Fast Failure Detection (FFD) 4.6.3. Fast Failure Detection (FFD)
The FFD function is a proactive function, used for fast detection of The FFD function is a proactive function, used for fast detection of
connectivity defects. While CV is typically sufficient for path connectivity defects. While CV is typically sufficient for path
failure detection and reporting, protection switching mechanisms failure detection and reporting, protection switching mechanisms
typically require faster detection. FFD is very similar to CV in typically require faster detection. FFD is very similar to CV in
terms of the packet format, and the possible defect conditions, but terms of the packet format, and the possible defect conditions, but
FFD allows a configurable transmission frequency. The default FFD allows a configurable transmission frequency. The default
transmission rate of FFD frames is 20 per second, i.e., every 50 ms, transmission rate of FFD frames is 20 per second, i.e., every 50 ms,
allowing fast detection for protection switching applications. allowing fast detection for protection switching applications.
4.5.4. Forward Defect Indication (FDI) 4.6.4. Forward Defect Indication (FDI)
The FDI function is used by an LSR to report a defect to affected The FDI function is used by an LSR to report a defect to affected
client layers, allowing them to suppress alarms about this defect. An client layers, allowing them to suppress alarms about this defect. An
FDI packets are sent at a rate of 1 per second. FDI packets are sent at a rate of 1 per second.
4.5.5. Backward Defect Indication (BDI) 4.6.5. Backward Defect Indication (BDI)
The BDI function is used to inform the LSR at an LSP trail The BDI function is used to inform the LSR at an LSP trail
termination source point about a defect condition in the forward termination source point about a defect condition in the forward
direction of an LSP. The LSR at the LSP trail termination sink point direction of an LSP. The LSR at the LSP trail termination sink point
transmits the BDI to the upstream LSR through the return path. BDI transmits the BDI to the upstream LSR through the return path. BDI
packets are sent at the same transmission rate as FDI. packets are sent at the same transmission rate as FDI.
4.6. ITU-T Y.1731 4.7. ITU-T Y.1731
4.6.1. Overview 4.7.1. Overview
The [ITU-T Y.1731] is a protocol for Ethernet OAM. It is presented in The [ITU-T Y.1731] is a protocol for Ethernet OAM. It is presented in
this document as a reference point, since the OAM mechanisms that are this document as a reference point, since the OAM mechanisms that are
currently being defined by the IETF for MPLS-TP are in many ways currently being defined by the IETF for MPLS-TP are in many ways
based on this standard. The standard defines various OAM functions, based on this standard. The standard defines various OAM functions,
including unidirectional and bidirectional continuity check, and including unidirectional and bidirectional continuity check, and
functions for performance monitoring. functions for performance monitoring.
4.6.2. ETH-CC 4.7.2. ETH-CC
The Ethernet Continuity Check function is a proactive function that The Ethernet Continuity Check function is a proactive function that
allows a MEP to detect loss of continuity with any of the other MEPs 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 in the MEG. This function also allows detection of other defect
conditions, such as unintended connectivity between two MEGs. The conditions, such as unintended connectivity between two MEGs. The
ETH-CC function is used for one of three possible applications: fault ETH-CC function is used for one of three possible applications: fault
management, performance monitoring (see 4.6.10.), and protection management, performance monitoring (see 4.6.10.), and protection
switching. switching.
Continuity Check Messages (CCM) are transmitted periodically at a Continuity Check Messages (CCM) are transmitted periodically at a
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o Mismerge: Occurs when a CCM is received from a peer MEP with an o Mismerge: Occurs when a CCM is received from a peer MEP with an
unexpected MEG ID. unexpected MEG ID.
o Unexpected MEP: Occurs when a CCM is received from a peer MEP with o Unexpected MEP: Occurs when a CCM is received from a peer MEP with
an unexpected transmitting MEP ID. an unexpected transmitting MEP ID.
o Unexpected period: Occurs when the transmission period field in o Unexpected period: Occurs when the transmission period field in
the CCM does not match the expected transmission period value. the CCM does not match the expected transmission period value.
4.6.3. ETH-LB 4.7.3. ETH-LB
The Ethernet loopback function verifies connectivity with a peer MEP The Ethernet loopback function verifies connectivity with a peer MEP
or MIP. The loopback function is performed on-demand, by sending a 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 loopback message (LBM) to the peer MEP or MIP. The peer node then
responds with a loopback reply (LBR). responds with a loopback reply (LBR).
More precisely, it is used for one of two purposes: More precisely, it is used for one of two purposes:
o Bidirectional connectivity test. o Bidirectional connectivity test.
o Bidirectional in-service / out-of-service test. The in-service 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- mode refers to a test that is run under traffic, while the out-of-
service test requires other traffic to be halted. service test requires other traffic to be halted.
4.6.4. ETH-TST 4.7.4. ETH-TST
The test function is very similar to the loopback function, but is The test function is very similar to the loopback function, but is
unidirectional, i.e., the ETH-TST PDUs are terminated by the receiver unidirectional, i.e., the ETH-TST PDUs are terminated by the receiver
rather than being looped back to the sender. rather than being looped back to the sender.
4.6.5. ETH-LT 4.7.5. ETH-LT
The Ethernet linktrace is an on-demand function that is used for path 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 discovery to a given target, or for locating a failure in a broken
path. path.
4.6.6. ETH-AIS 4.7.6. ETH-AIS
The Alarm Indication Signal indicates that a MEG should suppress The Alarm Indication Signal indicates that a MEG should suppress
alarms about a defect condition at a lower MEG level, i.e., since a 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 defect has occurred in a lower hierarchy in the network, it should
not be reported by the current node. not be reported by the current node.
A MEP that detects a failure periodically sends AIS messages to A MEP that detects a failure periodically sends AIS messages to
higher hierarchies. AIS messages are sent periodically at a higher hierarchies. AIS messages are sent periodically at a
recommended rate of 1 packet per second, until the defect condition recommended rate of 1 packet per second, until the defect condition
is resolved. is resolved.
4.6.7. ETH-LCK 4.7.7. ETH-LCK
The lock function is used for administrative locking. A MEP can The lock function is used for administrative locking. A MEP can
initiate administrative locking, resulting in interruption of data, initiate administrative locking, resulting in interruption of data,
e.g., for out-of-service ETH-LB or ETH-TST. e.g., for out-of-service ETH-LB or ETH-TST.
A MEP that initiates an administrative locking notifies its peer MEPs A MEP that initiates an administrative locking notifies its peer MEPs
to halt all relevant traffic until administrative/diagnostic to halt all relevant traffic until administrative/diagnostic
condition is removed. ETH-LCK frames are used to report to higher MEG 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, levels about the lock. The LCK frame, much like an AIS frame,
indicates to the receiving MEP that it should suppress alarms about indicates to the receiving MEP that it should suppress alarms about
the locked link. the locked link.
4.6.8. ETH-RDI 4.7.8. ETH-RDI
The Remote Defect Indication allows the sender to indicate that it The Remote Defect Indication allows the sender to indicate that it
encountered a defect conditions. The receiving MEPs are then aware encountered a defect conditions. The receiving MEPs are then aware
that there is a defect condition in the MEG. that there is a defect condition in the MEG.
4.6.9. ETH-APS 4.7.9. ETH-APS
The Y.1731 standard defines the frame format for Automatic Protection The Y.1731 standard defines the frame format for Automatic Protection
Switching frames. The protection switching operations are defined in Switching frames. The protection switching operations are defined in
other ITU-T standards. other ITU-T standards.
4.6.10. ETH-LM 4.7.10. ETH-LM
The loss measurement function allows a MEP to measure the packet loss 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 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 transmitted and received in-profile packets to/from each of its peer
MEPs. These counters are incorporated in the ETH-LM frames, allowing MEPs. These counters are incorporated in the ETH-LM frames, allowing
the MEPs to compute the packet loss rate. the MEPs to compute the packet loss rate.
The ETH-LM function measures the far-end loss, referring to traffic 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 FROM the MEP to its peer, as well as the near-end loss, referring to
traffic from the peer MEP TO the local MEP. traffic from the peer MEP TO the local MEP.
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o Single-ended LM: in this mode loss measurement is performed on- o Single-ended LM: in this mode loss measurement is performed on-
demand. The initiator sends an LM message (LMM) to its peer MEP, demand. The initiator sends an LM message (LMM) to its peer MEP,
and the peer responds with an LM reply (LMR). and the peer responds with an LM reply (LMR).
o Dual-ended LM: in this mode loss measurement is performed o Dual-ended LM: in this mode loss measurement is performed
proactively. The continuity check message (CCM) is used for proactively. The continuity check message (CCM) is used for
proactive LM. The LM counters are piggy-backed into the CCM, and proactive LM. The LM counters are piggy-backed into the CCM, and
allow proactive loss measurement. allow proactive loss measurement.
4.6.11. ETH-DM 4.7.11. ETH-DM
The delay measurement function is an on-demand function that allows a 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 to measure the frame delay and frame delay variation to a peer
MEP. MEP.
ETH-DM can be performed in one of two modes of operation: 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 o One-way DM: in this mode, a MEP transmits a 1DM frame containing
the time of its transmission, TxTimeStampf. The receiving MEP the time of its transmission, TxTimeStampf. The receiving MEP
receives the 1DM frame and records the time of reception, RxTimef. receives the 1DM frame and records the time of reception, RxTimef.
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peer MEP receives the DMM and responds with a delay measurement peer MEP receives the DMM and responds with a delay measurement
reply (DMR). Upon receiving the DMR, the initiating MEP records reply (DMR). Upon receiving the DMR, the initiating MEP records
the time of its reception, RxTimef, and computes the round trip the time of its reception, RxTimef, and computes the round trip
delay by: RxTimef - TxTimeStampf. delay by: RxTimef - TxTimeStampf.
Each MEP maintains a time-of-day clock that is used for timestamping 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 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 implicitly assumed that the clocks of the two peer MEPs are
synchronized by a time synchronization protocol. synchronized by a time synchronization protocol.
4.7. IEEE 802.1ag 4.8. IEEE 802.1ag
4.7.1. Overview 4.8.1. Overview
While the [ITU-T Y.1731] was defined in the ITU-T, the IEEE defined 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 the [IEEE 802.1ag] as a standard for connectivity fault management in
Ethernet based networks. While the two standards are to some extent Ethernet based networks. While the two standards are to some extent
overlapping, they can also be viewed as two complementary parts of a overlapping, they can also be viewed as two complementary parts of a
single Ethernet OAM picture. The two standards use a common packet single Ethernet OAM picture. The two standards use a common packet
format. There are a few differences between the two standards in format. There are a few differences between the two standards in
terms of terminology: the term MEG level, used in Y.1731, as referred 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 to as Maintenance Domain level in 802.1ag; the Y.1731 standard uses
the term MEG, while the 802.1ag equivalent is Maintenance Association the term MEG, while the 802.1ag equivalent is Maintenance Association
(MA). (MA).
While Y.1731 defines multiple OAM functions (see section 4.6), the While Y.1731 defines multiple OAM functions (see section 4.6), the
802.1ag standard focuses on three main OAM functions: continuity 802.1ag standard focuses on three main OAM functions: continuity
check, loopback, and linktrace, and defines them with great detail. check, loopback, and linktrace, and defines them with great detail.
4.7.2. Continuity Check 4.8.2. Continuity Check
See 4.6.2. See 4.6.2.
4.7.3. Loopback 4.8.3. Loopback
See 4.6.3. See 4.6.3.
4.7.4. Linktrace 4.8.4. Linktrace
See 4.6.5. See 4.6.5.
4.8. IEEE 802.3ah 4.9. IEEE 802.3ah
4.8.1. Overview 4.9.1. Overview
The [IEEE 802.3ah] defines an Ethernet link-layer OAM, for single-hop The [IEEE 802.3ah] defines an Ethernet link-layer OAM, for single-hop
Ethernet links. The OAM functions in this standard are described Ethernet links. The OAM functions in this standard are described
below. below.
4.8.2. Remote Failure Indication 4.9.2. Remote Failure Indication
This function allows a node to notify a peer about a defect in the This function allows a node to notify a peer about a defect in the
receive path. Some physical interfaces allow unidirectional traffic, receive path. Some physical interfaces allow unidirectional traffic,
where even if one direction of the link fails, the reverse direction where even if one direction of the link fails, the reverse direction
can still be used to convey the remote failure indication. can still be used to convey the remote failure indication.
4.8.3. Remote Loopback 4.9.3. Remote Loopback
The remote loopback function provides a diagnostic mode that is used The remote loopback function provides a diagnostic mode that is used
to verify the link connectivity, and to measure the packet loss rate. to verify the link connectivity, and to measure the packet loss rate.
When a bridge interface is configured to loopback mode, all incoming When a bridge interface is configured to loopback mode, all incoming
traffic through the interface is looped and sent back to the traffic through the interface is looped and sent back to the
originator. originator.
4.8.4. Link Monitoring 4.9.4. Link Monitoring
Link monitoring provides an event notification function, allowing Link monitoring provides an event notification function, allowing
peer devices to communicate defect conditions and diagnostic peer devices to communicate defect conditions and diagnostic
information. information.
4.9. MPLS-TP OAM 4.10. MPLS-TP OAM
4.9.1. Overview 4.10.1. Overview
The MPLS-TP is currently working on defining the OAM requirements and The MPLS working group is currently working on defining the OAM
mechanisms for MPLS-TP. The requirements of MPLS-TP OAM are defined requirements and mechanisms for MPLS-TP. The requirements of MPLS-TP
in [MPLS-TP OAM], and are described below. It is noted that these OAM are defined in [MPLS-TP OAM], and are described below.
requirements are in many ways similar to the requirement of Ethernet
OAM, as defined in [ITU-T Y.1731].
4.9.2. Continuity Checks MPLS-TP OAM traffic uses a Generic Associated Channel (G-ACh),
defined in [G-ACh]. This standard defines that MPLS-TP OAM traffic
uses:
o An Associated Channel Header (ACH), also known as a Control Word
in the PWE3 terminology, is a 4-byte header that is added to OAM
packets.
o A Generic Associated Label (GAL). The GAL is a reserved MPLS label
value. The reserved value is 13, and identifies the packet as an
MPLS-TP OAM packet. A GAL indicates the existence of the ACH
immediately after it.
The analysis in [OAM Analysis] discusses various OAM mechanism that
were considered in order to satisfy the requirements in [MPLS-TP
OAM]. The MPLS working group currently plans to use a mixture of OAM
mechanisms that are based on various existing standards, and adapt
them to the requirements of [MPLS-TP OAM]. Some of the main building
blocks of this solution are based on:
o Bidirectional Forwarding Detection ([BFD], [BFD LSP]) for
proactive connectivity verification.
o LSP Ping as defined in [LSP Ping] for on-demand connectivity
verification.
o Y.1731 per the [ITU-T Y.1731], mainly for performance measurement.
The requirements of MPLS-TP OAM are summarized below.
4.10.2. Continuity Checks
The continuity check is a proactive function that allows an End Point The continuity check is a proactive function that allows an End Point
to determine whether or not it receives traffic from its peer End to determine whether or not it receives traffic from its peer End
Points. Points.
4.9.3. Connectivity Verification 4.10.3. Connectivity Verification
The connectivity verification is a function that allows an End Point The connectivity verification is a function that allows an End Point
to verify its connectivity to a peer node. The connectivity check is to verify its connectivity to a peer node. The connectivity check is
performed by sending a connectivity verification PDU to the peer performed by sending a connectivity verification PDU to the peer
node, and receiving a reply within an expected time frame. This node, and receiving a reply within an expected time frame. This
function can be performed proactively or on-demand. function can be performed proactively or on-demand.
4.9.4. Diagnostic Tests 4.10.4. Diagnostic Tests
This function allows an End Point to perform an on-demand test, e.g., This function allows an End Point to perform an on-demand test, e.g.,
for bandwidth measurement. for bandwidth measurement.
4.9.5. Route Tracing 4.10.5. Route Tracing
This on-demand function is used for path discovery and for locating This on-demand function is used for path discovery and for locating
link failures. link failures.
4.9.6. Lock Instruct 4.10.6. Lock Instruct
The lock instruct function allows an End Point to instruct its peers The lock instruct function allows an End Point to instruct its peers
to enter an administrative status where all traffic is halted except to enter an administrative status where all traffic is halted except
the test traffic and OAM PDUs. the test traffic and OAM PDUs.
4.9.7. Lock Reporting 4.10.7. Lock Reporting
This function allows an Intermediate Point to report to an End Point This function allows an Intermediate Point to report to an End Point
about a lock condition. about a lock condition.
4.9.8. Alarm Reporting 4.10.8. Alarm Reporting
This function allows an Intermediate Point to report to an End Point This function allows an Intermediate Point to report to an End Point
about a defect condition. about a defect condition.
4.9.9. Remote Defect Indication 4.10.9. Remote Defect Indication
This is a proactive function that allows the sender to indicate that This is a proactive function that allows the sender to indicate that
it encountered a defect conditions. it encountered a defect conditions.
4.9.10. Client Failure Indication 4.10.10. Client Failure Indication
This function allows the MPLS-TP network to relay information about a This function allows the MPLS-TP network to relay information about a
fault condition in a client network, allowing the failure indication fault condition in a client network, allowing the failure indication
to propagate from end to end over the MPLS-TP network. to propagate from end to end over the MPLS-TP network.
4.9.11. Packet Loss Measurement 4.10.11. Packet Loss Measurement
This function measures the packet loss ratio between two peer End This function measures the packet loss ratio between two peer End
Points. It can be performed proactively or on-demand. Points. It can be performed proactively or on-demand.
4.9.12. Packet Delay Measurement 4.10.12. Packet Delay Measurement
This function measures the frame delay between two peer End Points. This function measures the frame delay between two peer End Points.
Two modes of operation are supported, one-way DM, and two-way DM. Two modes of operation are supported, one-way DM, and two-way DM.
4.10. Summary of OAM Functions 4.11. Summary of OAM Functions
Table 2 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 |Unidire|Bidirect|Path |Defect |Perform|Other | | Standard |Unidire|Bidirect|Path |Defect |Perform|Other |
| |ctional|ional |Discover|Indications|ance |Function| | |ctional|ional |Discover|Indications|ance |Function|
| |Connect|Connecti|y | |Monitor|s | | |Connect|Connecti|y | |Monitor|s |
| |ivity |vity | | |ing | | | |ivity |vity | | |ing | |
| |Check |Check | | | | | | |Check |Check | | | | |
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
|ICMP Ping | | Echo | | | | | |ICMP Ping | | Echo | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|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 | | | | | |PW VCCV | |VCCV | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IPPM | | | | |-Delay | |
| | | | | | measur| |
| | | | | | ement | |
| | | | | |-Packet| |
| | | | | | loss | |
| | | | | | measur| |
| | | | | | ement | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|ITU-T |-CV | | | | | | |ITU-T |-CV | | | | | |
|Y.1711 |-FFD | | | | | | |Y.1711 |-FFD | | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|ITU-T |ETH-CC |ETH-LB |ETH-LT |-ETH-RDI |-ETH-LM|-ETH-LCK| |ITU-T |ETH-CC |ETH-LB |ETH-LT |-ETH-RDI |-ETH-LM|-ETH-LCK|
|Y.1731 | | | |-ETH-AIS |-ETH-DM|-ETH-APS| |Y.1731 | | | |-ETH-AIS |-ETH-DM|-ETH-APS|
| | | | | | |-ETH-TST| | | | | | | |-ETH-TST|
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IEEE |CC |Loopback|Linktrac| | | | |IEEE |CC |Loopback|Linktrac| | | |
|802.1ag | | |e | | | | |802.1ag | | |e | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
skipping to change at page 19, line 29 skipping to change at page 24, line 14
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|MPLS-TP |CC |CV |Route |-Alarm |-LM |-Diagnos| |MPLS-TP |CC |CV |Route |-Alarm |-LM |-Diagnos|
|OAM | | |Tracing | Reporting |-DM | tic Tes| |OAM | | |Tracing | Reporting |-DM | tic Tes|
| | | | |-Client | | s | | | | | |-Client | | s |
| | | | | Failure | |-Lock | | | | | | Failure | |-Lock |
| | | | | Indication| | | | | | | | Indication| | |
| | | | |-Remote | | | | | | | |-Remote | | |
| | | | | Defect | | | | | | | | Defect | | |
| | | | | Indication| | | | | | | | Indication| | |
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
Table 2 Summary of OAM Functions Table 3 Summary of OAM Functions
4.11. Summary of Unidirectional Connectivity Check Mechanisms 4.12. Summary of Unidirectional Connectivity Check Mechanisms
A key element in some of the OAM standards that are analyzed in this A key element in some of the OAM standards that are analyzed in this
document is the unidirectional connectivity check. It is thus document is the unidirectional connectivity check. It is thus
interesting to present a more detailed comparison of the connectivity interesting to present a more detailed comparison of the connectivity
check mechanisms defined in OAM standards. Table 3 can be viewed as check mechanisms defined in OAM standards. Table 4 can be viewed as
an extension of Table 2, but is presented separately for convenience. an extension of Table 3, but is presented separately for convenience.
The table compares the OAM standards that support a unidirectional The table compares the OAM standards that support a unidirectional
connectivity check. MPLS-TP is not included in the comparison, as the connectivity check. MPLS-TP is not included in the comparison, as the
continuity check mechanism in MPLS-TP has not yet been defined. continuity check mechanism in MPLS-TP has not yet been defined.
The "Tx Interval" column in the table specifies the period between The "Tx Interval" column in the table specifies the period between
two consequent message transmissions, while the "Source Identifier" two consequent message transmissions, while the "Source Identifier"
column specifies the name of the field in the OAM packet that is used column specifies the name of the field in the OAM packet that is used
as the identifier of the transmitter. The "Error Codes" column as the identifier of the transmitter. The "Error Codes" column
specifies the possible error codes when the unidirectional specifies the possible error codes when the unidirectional
connectivity check detects a failure. connectivity check detects a failure.
skipping to change at page 20, line 34 skipping to change at page 25, line 18
|Y.1731 / | |le perio|MC | |-Unexpected MEG level | |Y.1731 / | |le perio|MC | |-Unexpected MEG level |
|IEEE | |ds: | | |-Mismerge | |IEEE | |ds: | | |-Mismerge |
|802.1ag | |3 1/3 ms| | |-Unexpected MEP | |802.1ag | |3 1/3 ms| | |-Unexpected MEP |
| | |10 ms | | |-Unexpected period | | | |10 ms | | |-Unexpected period |
| | |100 ms | | | | | | |100 ms | | | |
| | |1 s | | | | | | |1 s | | | |
| | |10 s | | | | | | |10 s | | | |
| | |1 min | | | | | | |1 min | | | |
| | |10 min | | | | | | |10 min | | | |
+-----------+-------+--------+---+--------+------------------------+ +-----------+-------+--------+---+--------+------------------------+
Table 3 Summary of OAM Terms Table 4 Summary of OAM Terms
5. Security Considerations 5. Security Considerations
There are no security implications imposed by this document. There are no security implications imposed by this document.
6. IANA Considerations 6. IANA Considerations
There are no new IANA considerations implied by this document. There are no new IANA considerations implied by this document.
7. Acknowledgments 7. Acknowledgments
skipping to change at page 21, line 16 skipping to change at page 25, line 43
8.1. Normative References 8.1. Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[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
Matsushima, S., "Operations and Management (OAM)
Requirements for Multi-Protocol Label Switched (MPLS)
Networks", RFC 4377, February 2006.
[MPLS OAM FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol
Label Switching (MPLS) Operations and Management
(OAM)", RFC 4378, February 2006.
[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
Multiprotocol Label Switching Architecture (MPLS)
Operation and Maintenance (OAM) Functions", RFC 3429,
November 2002.
[MPLS-TP OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for
OAM in MPLS Transport Networks", RFC 5860, May 2010.
[G-ACh] Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic
Associated Channel", RFC 5586, June 2009.
[VCCV] Nadeau, T., Pignataro, C., "Pseudowire Virtual Circuit [VCCV] Nadeau, T., Pignataro, C., "Pseudowire Virtual Circuit
Connectivity Verification (VCCV): A Control Channel Connectivity Verification (VCCV): A Control Channel
for Pseudowires", RFC 5085, December 2007. for Pseudowires", RFC 5085, December 2007.
[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.
[IPPM FW] Paxson, V., Almes, G., Mahdavi, J., and Mathis, M.,
"Framework for IP Performance Metrics", RFC 2330, May
1998.
[IPPM Con] Mahdavi, J., Paxson, V., "IPPM Metrics for Measuring
Connectivity", RFC 2678, September 1999.
[IPPM 1DM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
Delay Metric for IPPM", RFC 2679, September 1999.
[IPPM 1LM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
Packet Loss Metric for IPPM", RFC 2680, September
1999.
[IPPM 2DM] Almes, G., Kalidindi, S., Zekauskas, M., "A Round-trip
Delay Metric for IPPM", RFC 2681, September 1999.
[OWAMP] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and
Zekauskas, M., "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006.
[TWAMP] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and
Babiarz, J., "A Two-Way Active Measurement Protocol
(TWAMP)", RFC 5357, October 2008.
[BFD] Katz, D., Ward, D., "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
[BFD IP] Katz, D., Ward, D., "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June
2010.
[BFD Gen] Katz, D., Ward, D., "Generic Application of
Bidirectional Forwarding Detection (BFD)", RFC 5882,
June 2010.
[BFD Multi] Katz, D., Ward, D., "Bidirectional Forwarding Detection
(BFD) for Multihop Paths", RFC 5883, June 2010.
[BFD LSP] Aggarwal, R., Kompella, K., Nadeau, T., and Swallow,
G., "Bidirectional Forwarding Detection (BFD) for MPLS
Label Switched Paths (LSPs)", RFC 5884, June 2010.
[BFD VCCV] Nadeau, T., Pignataro, C., "Bidirectional Forwarding
Detection (BFD) for the Pseudowire Virtual Circuit
Connectivity Verification (VCCV)", RFC 5885, June
2010.
[IEEE 802.1ag]"Connectivity Fault Management", December 2007. [IEEE 802.1ag]"Connectivity Fault Management", December 2007.
[ITU-T Y.1731]"OAM Functions and Mechanisms for Ethernet-based [ITU-T Y.1731]"OAM Functions and Mechanisms for Ethernet-based
Networks", February 2008. Networks", February 2008.
[ITU-T Y.1711]"Operation & Maintenance mechanism for MPLS networks", [ITU-T Y.1711]"Operation & Maintenance mechanism for MPLS networks",
February 2004. February 2004.
[IEEE 802.3ah]"Media Access Control Parameters, Physical Layers, and [IEEE 802.3ah]"Media Access Control Parameters, Physical Layers, and
Management Parameters for Subscriber Access Networks", Management Parameters for Subscriber Access Networks",
clause 57, September 2004. clause 57, September 2004.
8.2. Informative References 8.2. Informative References
[MPLS-TP OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for [P2MP Ping] Saxena, S., Farrel, A. , Yasukawa, S., "Detecting Data
OAM in MPLS Transport Networks", draft-ietf-mpls-tp- Plane Failures in Point-to-Multipoint Multiprotocol
oam-requirements, August 2009. Label Switching (MPLS) - Extensions to LSP Ping",
draft-ietf-mpls-p2mp-lsp-ping, March 2010.
[BFD] Katz, D., Ward, D., "Bidirectional Forwarding
Detection", draft-ietf-bfd-base, February 2009.
[P2MP Ping] Farrel, A. , Yasukawa, S., "Detecting Data Plane
Failures in Point-to-Multipoint Multiprotocol Label
Switching (MPLS) - Extensions to LSP Ping", draft-
ietf-mpls-p2mp-lsp-ping, August 2009.
[OAM Soup] Betts, M., Van Helvoort, H., Bonica, R., Romascanu, D., [OAM Soup] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu,
"The OAM Acronym Soup", draft-ietf-opsawg-mpls-tp-oam- D., Mansfield, S., "The OAM Acronym Soup", draft-ietf-
def, September 2009. opsawg-mpls-tp-oam-def, June 2010.
[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.
[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", draft-ietf-mpls-tp-rosetta-stone, Recommendations", draft-ietf-mpls-tp-rosetta-stone,
June 2009. May 2010.
[MPLS-TP Ping BFD] Bahadur, N., Aggarwal, R., Ward, D., Nadeau, T.,
Sprecher, N., Weingarten, Y., "LSP-Ping and BFD
encapsulation over ACH", draft-ietf-mpls-tp-lsp-ping-
bfd-procedures, March 2010.
[OAM Analysis] Sprecher, N., Bellagamba, E., Weingarten, Y., "MPLS-TP
OAM Analysis", draft-ietf-mpls-tp-oam-analysis, July
2010.
Authors' Addresses Authors' Addresses
Tal Mizrahi Tal Mizrahi
Marvell Marvell
Email: talmi@marvell.com Email: talmi@marvell.com
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