draft-ietf-opsawg-oam-overview-07.txt   draft-ietf-opsawg-oam-overview-08.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: March 2013 Nokia Siemens Networks Expires: July 2013 Nokia Siemens Networks
E. Bellagamba E. Bellagamba
Ericsson Ericsson
Y. Weingarten Y. Weingarten
September 12, 2012 January 9, 2013
An Overview of An Overview of
Operations, Administration, and Maintenance (OAM) Mechanisms Operations, Administration, and Maintenance (OAM) Mechanisms
draft-ietf-opsawg-oam-overview-07.txt draft-ietf-opsawg-oam-overview-08.txt
Abstract Abstract
Operations, Administration, and Maintenance (OAM) is a general term Operations, Administration, and Maintenance (OAM) is a general term
that refers to a toolset that can be used for fault detection and that refers to a toolset that can be used for fault detection and
isolation, and for performance measurement. OAM mechanisms have been isolation, and for performance measurement. OAM mechanisms have been
defined for various layers in the protocol stack, and are used with a defined for various layers in the protocol stack, and are used with a
variety of protocols. 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
skipping to change at page 1, line 48 skipping to change at page 1, line 48
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on March 12, 2013. This Internet-Draft will expire on July 9, 2013.
Copyright Notice Copyright Notice
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction ................................................. 3 1. Introduction ................................................. 3
1.1. Background .............................................. 3 1.1. The Building Blocks of OAM .............................. 3
1.2. The OAM toolsets ........................................ 4 1.2. Forwarding Plane vs. Management Plane ................... 4
1.3. IETF OAM Standards ...................................... 5 1.3. The OAM toolsets ........................................ 4
1.4. Non-IETF OAM Standards .................................. 8 1.4. IETF OAM Documents ...................................... 6
2. Basic Terminology ............................................ 9 1.5. Non-IETF OAM Documents ................................. 10
2.1. Abbreviations ........................................... 9 2. Basic Terminology ........................................... 12
2.2. Terminology used in OAM Standards ...................... 10 2.1. Abbreviations .......................................... 12
2.2.1. General Terms ..................................... 10 2.2. Terminology used in OAM Standards ...................... 13
2.2.2. OAM Maintenance Entities .......................... 11 2.2.1. General Terms ..................................... 13
2.2.3. OAM Maintenance Points ............................ 11 2.2.2. OAM Maintenance Entities .......................... 13
2.2.4. Proactive and On-demand activation ................ 12 2.2.3. OAM Maintenance Points ............................ 14
2.2.5. Connectivity Verification and Continuity Checks ... 12 2.2.4. Proactive and On-demand activation ................ 15
2.2.6. Failures .......................................... 13 2.2.5. Connectivity Verification and Continuity Checks ... 15
3. OAM Tools ................................................... 13 2.2.6. Failures .......................................... 15
3.1. ICMP Ping .............................................. 13 3. OAM Tools ................................................... 16
3.2. Traceroute ............................................. 13 3.1. IP Ping and Traceroute ................................. 16
3.3. Bidirectional Forwarding Detection (BFD) ............... 14 3.1.1. Ping .............................................. 16
3.3.1. Overview .......................................... 14 3.1.2. Traceroute......................................... 16
3.3.2. BFD Control ....................................... 14 3.2. Bidirectional Forwarding Detection (BFD) ............... 17
3.3.3. BFD Echo .......................................... 15 3.2.1. Overview .......................................... 17
3.4. LSP Ping ............................................... 15 3.2.2. BFD Control ....................................... 17
3.5. PWE3 Virtual Circuit Connectivity Verification (VCCV) .. 16 3.2.3. BFD Echo .......................................... 18
3.6. IP Performance Metrics (IPPM) .......................... 17 3.3. MPLS OAM ............................................... 18
3.6.1. Overview .......................................... 17 3.4. MPLS-TP OAM ............................................ 19
3.6.2. Control and Test Protocols ........................ 17 3.4.1. Overview .......................................... 19
3.6.3. OWAMP ............................................. 18 3.4.2. Generic Associated Channel ........................ 19
3.6.4. TWAMP ............................................. 18 3.4.3. MPLS-TP OAM Toolset ............................... 20
3.7. MPLS-TP OAM ............................................ 19 3.4.3.1. Continuity Check and Connectivity Verification 20
3.7.1. Overview .......................................... 19 3.4.3.2. Route Tracing ................................ 21
3.7.2. Generic Associated Channel ........................ 19 3.4.3.3. Lock Instruct ................................ 21
3.7.3. MPLS-TP OAM Toolset ............................... 20 3.4.3.4. Lock Reporting ............................... 21
3.7.3.1. Continuity Check and Connectivity Verification 20 3.4.3.5. Alarm Reporting .............................. 21
3.7.3.2. Route Tracing ................................ 21 3.4.3.6. Remote Defect Indication ..................... 22
3.7.3.3. Lock Instruct ................................ 21 3.4.3.7. Client Failure Indication .................... 22
3.7.3.4. Lock Reporting ............................... 21 3.4.3.8. Packet Loss Measurement (LM) ................. 22
3.7.3.5. Alarm Reporting .............................. 21 3.4.3.9. Packet Delay Measurement (DM) ................ 22
3.7.3.6. Remote Defect Indication ..................... 22 3.5. PWE3 OAM ............................................... 23
3.7.3.7. Client Failure Indication .................... 22 3.5.1. PWE3 OAM using Virtual Circuit Connectivity Verification
3.7.3.8. Packet Loss Measurement ...................... 22 (VCCV) ................................................... 23
3.7.3.9. Packet Delay Measurement ..................... 22 3.5.2. PWE3 OAM using G-ACh .............................. 24
3.8. Summary of OAM Functions ............................... 23 3.6. OWAMP and TWAMP......................................... 24
4. Security Considerations ..................................... 24 3.6.1. Overview .......................................... 24
5. IANA Considerations ......................................... 24 3.6.2. Control and Test Protocols ........................ 24
6. Acknowledgments ............................................. 24 3.6.3. OWAMP ............................................. 25
7. References .................................................. 24 3.6.4. TWAMP ............................................. 26
7.1. Normative References ................................... 24 3.7. Summary of OAM Functions ............................... 26
7.2. Informative References ................................. 27 4. Security Considerations ..................................... 27
5. IANA Considerations ......................................... 27
6. Acknowledgments ............................................. 27
7. References .................................................. 28
7.1. Normative References ................................... 28
7.2. Informative References ................................. 31
1. Introduction 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 for detecting,
detecting, isolating and reporting connection failures or measurement isolating and reporting connection failures and performance
of connection performance parameters. The term OAM has been used over degradation.
the years in several different contexts, as discussed in [OAM-Def].
This term as been associated with the 3 logical abstraction layers:
the forwarding plane, the control plane, and the management plane. In
the context of this document OAM refers to Operations,
Administration, and Maintenance. Hence, management aspects are
outside the scope of this document.
1.1. Background This document summarizes the OAM tools and mechanisms defined in the
IETF.
The communication of a network may be configured and maintained by The term OAM in this document refers to Operations, Administration
use of various tools at different layers - these include use of a and Maintenance [OAM-Def], focusing on the forwarding plane of OAM.
control plane or management plane to configure and maintain the Hence, management aspects are outside the scope of this document.
connectivity of the network from the outside - looking in - and
controlling the connections when the need arises. OAM, on the other 1.1. The Building Blocks of OAM
hand, traditionally has been used to maintain the connectivity in-
band with the actual data traffic, i.e. in the data plane. An OAM protocol is run in the context of a Maintenance Domain,
consisting of two or more nodes that run the OAM protocol, referred
to as Maintenance Points (MP).
This subsection provides a brief summary of the common tools used by
OAM protocols. An OAM protocol typically supports one or more of the
tools described below.
o Continuity Checking (CC):
Used for verifying the liveness of a connection between two MPs.
o Connectivity Verification (CV):
Allows an MP to check whether it is connected to a peer MP, and to
verify that messages from the peer MP are received through the
expected path.
o Path Discovery / Fault Localization:
An MP uses this mechanism to trace the route to a peer MP, i.e.,
to identify the nodes along the path to the peer MP. When a
connection fails, this mechanism also allows the MP to detect the
location of the failure.
o Performance Monitoring:
Consists of 3 main functions
o Loss Measurement (LM) - monitors the packet loss rate of a
connection.
o Delay Measurement (DM) - monitors the delay and delay
variation between MPs.
o Throughput measurement - monitors the throughput of a
connection.
1.2. Forwarding Plane vs. Management Plane
While the OAM tools may, and quite often do, work in conjunction with While the OAM tools may, and quite often do, work in conjunction with
a control-plane or management plane, they are usually defined to be a control-plane or management plane, they are usually defined to be
independent of the control-plane. The OAM tools communicate with the independent of the control-plane. The OAM tools communicate with the
management plane to raise alarms, and often the on-demand tools may management plane to raise alarms, and often the on-demand tools may
be activated by the management, e.g. to locate and localize problems. be activated by the management, e.g. to locate and localize problems.
The considerations of the control-plane maintenance tools or the The considerations of the control-plane maintenance tools or the
functionality of the management-plane are out of scope for this functionality of the management-plane are out of scope for this
document, which will concentrate on presenting the data-plane tools document, which will concentrate on presenting the forwarding-plane
that are used for OAM. tools that are used for OAM.
1.2. The OAM toolsets 1.3. The OAM toolsets
This memo provides an overview of the different sets of OAM This memo provides an overview of the different sets of OAM
mechanisms defined by the IETF. It is intended for those with little mechanisms defined by the IETF. It is intended for those with little
or no familiarity with the described mechanisms. The set of OAM or no familiarity with the described mechanisms. The set of OAM
mechanisms described in this memo are applicable to IP unicast, MPLS, mechanisms described in this memo are applicable to IP unicast, MPLS,
pseudowires, and MPLS for the transport environment (MPLS-TP). While pseudowires, and MPLS for the transport environment (MPLS-TP). While
OAM mechanisms that are applicable to other technologies exist, they OAM mechanisms that are applicable to other technologies exist, they
are beyond the scope of this memo. This document focuses on IETF are beyond the scope of this memo. This document focuses on IETF
documents that have been published as RFCs, while other ongoing OAM- documents that have been published as RFCs, while other ongoing OAM-
related work is outside the scope. related work is outside the scope.
The IETF has defined OAM protocols and mechanisms in several The IETF has defined OAM protocols and mechanisms in several
different fronts: different fronts:
o ICMP Ping: o IP Ping and Traceroute:
ICMP Echo request, also known as Ping, as defined in [ICMPv4], and Ping is a very simple and common application for failure diagnosis
[ICMPv6]. ICMP Ping is a very simple and basic mechanism in that uses ICMP Echo requests, as defined in [ICMPv4], and
failure diagnosis. LSP Ping is to some extent based on ICMP Ping. [ICMPv6].
Traceroute ([TCPIP-Tools], [NetTools]) is an application that
o IPPM: allows users to trace the path between an IP source and an IP
IP Performance Metrics (IPPM) is a working group in the IETF that destination, i.e., to identify the nodes along the path.
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: o BFD:
Bidirectional Forwarding Detection (BFD) is defined in [BFD] as a 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 MPLS OAM:
MPLS LSP Ping, as defined in [MPLS-OAM], [MPLS-OAM-FW] and [LSP-
Ping], is an OAM mechanism for point to point MPLS LSPs. It
includes two main functions: Ping and Traceroute.
o MPLS-TP OAM:
MPLS-TP OAM is defined in a set of RFCs. The OAM requirements for
MPLS Transport Profile (MPLS-TP) are defined in [MPLS-TP-OAM].
Each of the tools in the OAM toolset is defined in its own RFC, as
specified in Section 1.4.
o PWE3 OAM:
The PWE3 OAM architecture defines control channels that support
the use of existing IETF OAM tools to be used for a pseudowire
(PW). The control channels that are defined in [VCCV] and [PW-G-
ACH] may be used in conjunction with ICMP Ping, LSP Ping, and BFD
to perform CC and CV functionality. In addition the channels
support use of any of the MPLS-TP based OAM tools for completing
their respective OAM functionality for a PW.
o OWAMP and TWAMP:
The One Way Active Measurement Protocol (OWAMP) and the Two Way
Active Measurement Protocols (TWAMP) are two protocols defined in
the IP Performance Metrics (IPPM) working group in the IETF. These
protocols allow delay and packet loss measurement in IP networks.
This document summarizes the OAM mechanisms defined by the IETF. We This document summarizes the OAM mechanisms defined by the IETF. 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.
1.3. IETF OAM Standards 1.4. IETF OAM Documents
Table 1 summarizes the IETF OAM standards discussed in this document. Table 1 summarizes the IETF OAM related RFCs discussed in this
document.
The table includes a "Type" column, specifying the nature of each of The table includes a "Type" column, specifying the nature of each of
the listed documents: the listed documents:
o Tool: documents that define an OAM tool or mechanism. o Tool: documents that define an OAM tool or mechanism.
o Prof.: documents that define a profile or a variant for an OAM o Prof.: documents that define a profile or a variant for an OAM
tool that is defined in other documents. tool that is defined in other documents.
o Inf.: documents that define an infrastructure that is used by OAM o Inf.: documents that define an infrastructure that is used by OAM
tools. tools.
o Misc.: other OAM related documents, e.g., OAM requirement and o Misc.: other OAM related documents, e.g., OAM requirement and
framework documents. framework documents.
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
| | Title |Type | RFC | | | Title |Type | RFC |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|ICMPv4 Ping| Internet Control Message Protocol |Tool | RFC 792 | |IP Ping and| Internet Control Message Protocol |Tool | RFC 792 |
| | | | | |Traceroute | [ICMPv4] | | |
+-----------+--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
|ICMPv6 Ping| Internet Control Message Protocol |Tool | RFC 4443 | | | Internet Control Message Protocol |Tool | RFC 4443 |
| | (ICMPv6) for the Internet Protocol | | | | | (ICMPv6) for the Internet Protocol | | |
| | Version 6 (IPv6) Specification | | | | | Version 6 (IPv6) Specification | | |
+-----------+--------------------------------------+-----+----------+ | | [ICMPv6] | | |
|Traceroute | A Primer On Internet and TCP/IP |Tool | RFC 2151 | | +--------------------------------------+-----+----------+
| | Tools and Utilities | | | | | A Primer On Internet and TCP/IP |Tool | RFC 2151 |
| | Tools and Utilities [TCPIP-Tools] | | |
| +--------------------------------------+-----+----------+
| | FYI on a Network Management Tool |Tool | RFC 1147 |
| | Catalog: Tools for Monitoring and | | |
| | Debugging TCP/IP Internets and | | |
| | Interconnected Devices [NetTools] | | |
| +--------------------------------------+-----+----------+
| | Extended ICMP to Support Multi-Part |Tool | RFC 4884 |
| | Messages [ICMP-MP] | | |
| +--------------------------------------+-----+----------+
| | ICMP Extensions for Multiprotocol |Tool | RFC 4950 |
| | Label Switching [ICMP-Ext] | | |
| +--------------------------------------+-----+----------+
| | Extending ICMP for Interface and |Tool | RFC 5837 |
| | Next-Hop Identification [ICMP-Int] | | |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|BFD | Bidirectional Forwarding Detection |Tool | RFC 5880 | |BFD | Bidirectional Forwarding Detection |Tool | RFC 5880 |
| | [BFD] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5881 | | | Bidirectional Forwarding Detection |Prof.| RFC 5881 |
| | (BFD) for IPv4 and IPv6 (Single Hop) | | | | | (BFD) for IPv4 and IPv6 (Single Hop) | | |
| | [BFD-IP] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Generic Application of Bidirectional |Misc.| RFC 5882 | | | Generic Application of Bidirectional |Misc.| RFC 5882 |
| | Forwarding Detection | | | | | Forwarding Detection [BFD-Gen] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5883 | | | Bidirectional Forwarding Detection |Prof.| RFC 5883 |
| | (BFD) for Multihop Paths | | | | | (BFD) for Multihop Paths [BFD-Multi] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5884 | | | Bidirectional Forwarding Detection |Prof.| RFC 5884 |
| | for MPLS Label Switched Paths (LSPs) | | | | | for MPLS Label Switched Paths (LSPs) | | |
| | [BFD-LSP] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5885 | | | Bidirectional Forwarding Detection |Prof.| RFC 5885 |
| | for the Pseudowire Virtual Circuit | | | | | for the Pseudowire Virtual Circuit | | |
| | Connectivity Verification (VCCV) | | | | | Connectivity Verification (VCCV) | | |
| | [BFD-VCCV] | | |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|IETF MPLS | Operations and Management (OAM) |Misc.| RFC 4377 | |MPLS OAM | Operations and Management (OAM) |Misc.| RFC 4377 |
|OAM | Requirements for Multi-Protocol Label| | | | | Requirements for Multi-Protocol Label| | |
|(LSP Ping) | Switched (MPLS) Networks | | | | | Switched (MPLS) Networks [MPLS-OAM] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | A Framework for Multi-Protocol |Misc.| RFC 4378 | | | A Framework for Multi-Protocol |Misc.| RFC 4378 |
| | Label Switching (MPLS) Operations | | | | | Label Switching (MPLS) Operations | | |
| | and Management (OAM) | | | | | and Management (OAM) [MPLS-OAM-FW] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Detecting Multi-Protocol Label |Tool | RFC 4379 | | | Detecting Multi-Protocol Label |Tool | RFC 4379 |
| | Switched (MPLS) Data Plane Failures | | | | | Switched (MPLS) Data Plane Failures | | |
| | [LSP-Ping] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Operations and Management (OAM) |Misc.| RFC 4687 | | | Operations and Management (OAM) |Misc.| RFC 4687 |
| | Requirements for Point-to-Multipoint | | | | | Requirements for Point-to-Multipoint | | |
| | MPLS Networks | | | | | MPLS Networks [MPLS-P2MP] | | |
| +--------------------------------------+-----+----------+
| | ICMP Extensions for Multiprotocol |Tool | RFC 4950 |
| | Label Switching | | |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|MPLS-TP | Requirements for OAM in MPLS-TP |Misc.| RFC 5860 | |MPLS-TP | Requirements for OAM in MPLS-TP |Misc.| RFC 5860 |
|OAM +--------------------------------------+-----+----------+ |OAM | [MPLS-TP-OAM] | | |
| +--------------------------------------+-----+----------+
| | MPLS Generic Associated Channel |Inf. | RFC 5586 | | | MPLS Generic Associated Channel |Inf. | RFC 5586 |
| | [G-ACh] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | MPLS-TP OAM Framework |Misc.| RFC 6371 | | | MPLS-TP OAM Framework |Misc.| RFC 6371 |
| | [TP-OAM-FW] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Proactive Connectivity Verification, |Tool | RFC 6428 | | | Proactive Connectivity Verification, |Tool | RFC 6428 |
| | Continuity Check, and Remote Defect | | | | | Continuity Check, and Remote Defect | | |
| | Indication for the MPLS Transport | | | | | Indication for the MPLS Transport | | |
| | Profile | | | | | Profile [TP-CC-CV] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | MPLS On-Demand Connectivity |Tool | RFC 6426 | | | MPLS On-Demand Connectivity |Tool | RFC 6426 |
| | Verification and Route Tracing | | | | | Verification and Route Tracing | | |
| | [OnDemand-CV] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | MPLS Fault Management Operations, |Tool | RFC 6427 | | | MPLS Fault Management Operations, |Tool | RFC 6427 |
| | Administration, and Maintenance (OAM)| | | | | Administration, and Maintenance (OAM)| | |
| | [TP-Fault] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | MPLS Transport Profile Lock Instruct |Tool | RFC 6435 | | | MPLS Transport Profile Lock Instruct |Tool | RFC 6435 |
| | and Loopback Functions | | | | | and Loopback Functions [Lock-Loop] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | Packet Loss and Delay Measurement for|Tool | RFC 6374 | | | Packet Loss and Delay Measurement for|Tool | RFC 6374 |
| | MPLS Networks | | | | | MPLS Networks [MPLS-LM-DM] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | A Packet Loss and Delay Measurement |Prof.| RFC 6375 | | | A Packet Loss and Delay Measurement |Prof.| RFC 6375 |
| | Profile for MPLS-Based Transport | | | | | Profile for MPLS-Based Transport | | |
| | Networks | | | | | Networks [TP-LM-DM] | | |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|PW VCCV | Pseudowire Virtual Circuit |Inf. | RFC 5085 | |PWE3 OAM | Pseudowire Virtual Circuit |Inf. | RFC 5085 |
| | Connectivity Verification (VCCV): | | | | | Connectivity Verification (VCCV): | | |
| | A Control Channel for Pseudowires | | | | | A Control Channel for Pseudowires | | |
| | [VCCV] | | |
| +--------------------------------------+-----+----------+
| | Bidirectional Forwarding Detection |Prof.| RFC 5885 |
| | for the Pseudowire Virtual Circuit | | |
| | Connectivity Verification (VCCV) | | |
| | [BFD-VCCV] | | |
| +--------------------------------------+-----+----------+
| | Using the Generic Associated Channel |Inf. | RFC 6423 |
| | Label for Pseudowire in the MPLS | | |
| | Transport Profile (MPLS-TP) | | |
| | [PW-G-ACh] | | |
| +--------------------------------------+-----+----------+
| | Pseudowire (PW) Operations, |Misc.| RFC 6310 |
| | Administration, and Maintenance (OAM)| | |
| | Message Mapping [PW-Map] | | |
+-----------+--------------------------------------+-----+----------+ +-----------+--------------------------------------+-----+----------+
|IPPM | Framework for IP Performance Metrics |Misc.| RFC 2330 | |OWAMP and | A One-way Active Measurement Protocol|Tool | RFC 4656 |
|TWAMP | [OWAMP] | | |
| +--------------------------------------+-----+----------+
| | A Two-Way Active Measurement Protocol|Tool | RFC 5357 |
| | [TWAMP] | | |
| +--------------------------------------+-----+----------+
| | Framework for IP Performance Metrics |Misc.| RFC 2330 |
| | [IPPM-FW] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | IPPM Metrics for Measuring |Misc.| RFC 2678 | | | IPPM Metrics for Measuring |Misc.| RFC 2678 |
| | Connectivity | | | | | Connectivity [IPPM-Con] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | A One-way Delay Metric for IPPM |Misc.| RFC 2679 | | | A One-way Delay Metric for IPPM |Misc.| RFC 2679 |
| | [IPPM-1DM] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | A One-way Packet Loss Metric for IPPM|Misc.| RFC 2680 | | | A One-way Packet Loss Metric for IPPM|Misc.| RFC 2680 |
| | [IPPM-1LM] | | |
| +--------------------------------------+-----+----------+ | +--------------------------------------+-----+----------+
| | A Round-trip Delay Metric for IPPM |Misc.| RFC 2681 | | | A Round-trip Delay Metric for IPPM |Misc.| RFC 2681 |
| +--------------------------------------+-----+----------+ | | [IPPM-2DM] | | |
| | 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 Table 1 Summary of IETF OAM Related RFCs
1.4. Non-IETF OAM Standards 1.5. Non-IETF OAM Documents
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 that focus on ITU-T have also defined various OAM mechanisms that focus on
Ethernet, and various other transport network environments. These Ethernet, and various other transport network environments. These
various mechanisms, defined by the three standard organizations, are various mechanisms, defined by the three standard organizations, are
often tightly coupled, and have had a mutual effect on each other. often tightly coupled, and have had a mutual effect on each other.
The ITU-T and IETF have both defined OAM mechanisms for MPLS LSPs, 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 the [ITU-T-Y1711] and [LSP-Ping]. The following OAM standards by the IEEE
IEEE and ITU-T are to some extent linked to IETF OAM mechanisms and ITU-T are to some extent linked to IETF OAM mechanisms listed
listed above and are mentioned here only as reference material: 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-Y1731], and by the IEEE in [IEEE802.1ag].
802.1ag]. The IEEE 802.3 standard defines OAM for one-hop Ethernet The IEEE 802.3 standard defines OAM for one-hop Ethernet links
links [IEEE-802.3ah]. [IEEE802.3ah].
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-Y1711], and
MPLS-TP OAM in [ITU-G8113.1] and [ITU-G8113.2].
Table 2 summarizes the OAM standards mentioned in this document. This Table 2 summarizes the OAM standards mentioned in this document. This
document focuses on IETF OAM standards, but these non-IETF standards document focuses on IETF OAM standards, but these non-IETF standards
are referenced where relevant. are referenced where relevant.
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
| | Title |Standard/Draft | | | Title |Standard/Draft |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|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 [ITU-T-Y1711] | |
| +--------------------------------------+---------------+ | +--------------------------------------+---------------+
| | 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 | |
| | [OAM-Label] | |
| | | | | | | |
| | Note: although this is an IETF | | | | Note: although this is an IETF | |
| | document, it is listed as one of the| | | | document, it is listed as one of the| |
| | non-IETF OAM standards, since it | | | | non-IETF OAM standards, since it | |
| | was defined as a complementary part | | | | was defined as a complementary part | |
| | of Y.1711. | | | | of ITU-T Y.1711. | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|ITU-T | OAM Functions and Mechanisms for |[ITU-T-Y.1731] | |ITU-T | Operations, administration and |ITU-T G.8113.2 |
|MPLS-TP OAM| Maintenance mechanisms for MPLS-TP | |
| | networks using the tools defined for | |
| | MPLS [ITU-G8113.2] | |
| | | |
| | Note: this document describes the | |
| | OAM toolset defined by the IETF for | |
| | MPLS-TP, whereas ITU-T G.8113.1 | |
| | describes the OAM toolset defined | |
| | by the ITU-T. | |
| +--------------------------------------+---------------+
| | Operations, Administration and |ITU-T G.8113.1 |
| | Maintenance mechanism for MPLS-TP in | |
| | Packet Transport Network (PTN) | |
| +--------------------------------------+---------------+
| | Allocation of a Generic Associated | RFC 6671 |
| | Channel Type for ITU-T MPLS Transport| |
| | Profile Operation, Maintenance, and | |
| | Administration (MPLS-TP OAM) | |
| | [ITU-T-CT] | |
| | | |
| | Note: although this is an IETF | |
| | document, it is listed as one of the| |
| | non-IETF OAM standards, since it | |
| | was defined as a complementary part | |
| | of ITU-T G.8113.1. | |
+-----------+--------------------------------------+---------------+
|ITU-T | OAM Functions and Mechanisms for |[ITU-T-Y1731] |
|Ethernet | Ethernet-based Networks | | |Ethernet | Ethernet-based Networks | |
|OAM | | | |OAM | | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|IEEE | Connectivity Fault Management |[IEEE-802.1ag] | |IEEE | Connectivity Fault Management | IEEE 802.1ag |
|CFM | | | |CFM | [IEEE802.1ag] | |
| | | |
| | Note: CFM was originally published | |
| | as IEEE 802.1ag, but is now | |
| | incorporated in the 802.1Q standard.| |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
|IEEE | Media Access Control Parameters, |[IEEE-802.3ah] | |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 [IEEE802.3ah] | |
| | | |
| | Note: link level OAM was originally | |
| | defined in IEEE 802.3ah, and is now | |
| | incorporated in the 802.3 standard. | |
+-----------+--------------------------------------+---------------+ +-----------+--------------------------------------+---------------+
Table 2 Non-IETF OAM Standards Mentioned in this Document Table 2 Non-IETF OAM Standards Mentioned in this Document
2. Basic Terminology 2. Basic Terminology
2.1. Abbreviations 2.1. Abbreviations
ACH Associated Channel Header ACH Associated Channel Header
AIS Alarm Indication Signal AIS Alarm Indication Signal
BFD Bidirectional Forwarding Detection BFD Bidirectional Forwarding Detection
CC Continuity Check CC Continuity Check
CCM Continuity Check Message
CV Connectivity Verification CV Connectivity Verification
DM Delay Measurement DM Delay Measurement
FEC Forwarding Equivalence Class FEC Forwarding Equivalence Class
GAL Generic Associated Label GAL Generic Associated Label
ICMP Internet Control Message Protocol ICMP Internet Control Message Protocol
L2TP Layer Two Tunneling Protocol
LCCE L2TP Control Connection Endpoint
LDP Label Distribution Protocol LDP Label Distribution Protocol
LM Loss Measurement LM Loss Measurement
LOC Loss Of Continuity
LSP Label Switched Path LSP Label Switched Path
LSR Label Switching Router
ME Maintenance Entity ME Maintenance Entity
MEG Maintenance Entity Group MEG Maintenance Entity Group
MEP MEG End Point MEP MEG End Point
MIP MEG Intermediate Point MIP MEG Intermediate Point
MP Maintenance Point MP Maintenance Point
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MEG Maintenance Entity Group MEG Maintenance Entity Group
MEP MEG End Point MEP MEG End Point
MIP MEG 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 MTU Maximum Transmission Unit
OAM Operations, Administration, and Maintenance OAM Operations, Administration, and Maintenance
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
VCCV Virtual Circuit Connectivity Verification VCCV Virtual Circuit Connectivity Verification
2.2. Terminology used in OAM Standards 2.2. Terminology used in OAM Standards
2.2.1. 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 terms relevant to that tool. A thesaurus of terminology for defines terms relevant to that tool. A thesaurus of terminology for
MPLS-TP terms is presented in [MPLS-TP-Term], and provides a good MPLS-TP terms is presented in [TP-Term], and provides a good summary
summary of some of the OAM related terminology. 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. this document.
2.2.2. OAM Maintenance Entities 2.2.2. OAM Maintenance Entities
OAM tools are designed to monitor and manage a Maintenance Entity OAM tools are designed to monitor and manage a Maintenance Entity
(ME). An ME, as defined in [TP-OAM-FW], defines a relationship (ME). An ME, as defined in [TP-OAM-FW], defines a relationship
skipping to change at page 11, line 31 skipping to change at page 14, line 14
o MIP: In between MEPs, there are zero or more intermediate points, o MIP: In between MEPs, there are zero or more intermediate points,
called Maintenance Entity Group Intermediate Points (MIPs). called Maintenance Entity Group Intermediate Points (MIPs).
A pair of MEPs engaged in an ME are connected by a communication 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 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 physical connection, a set of physical connections, or a virtual link
such as an MPLS LSP. such as an MPLS LSP.
The term Maintenance Entity (ME) is used in ITU-T Recommendations 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- (e.g. [ITU-T-Y1731]), as well as in the MPLS-TP terminology ([TP-OAM-
OAM-FW]). Various terms are used to refer to an ME. For example, BFD FW]). Various terms are used to refer to an ME. For example, BFD does
does not explicitly use a term that is equivalent to ME, but rather not explicitly use a term that is equivalent to ME, but rather uses
uses the term "session", referring to the relationship between two the term "session", referring to the relationship between two nodes
nodes using a BFD protocol. The MPLS LSP Ping ([LSP-Ping]) using a BFD protocol. The MPLS LSP Ping ([LSP-Ping]) terminology
terminology simply uses the term "LSP" in this context. 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 [TP-OAM-FW], similar to the terms defined by ITU-T. A MEG allows 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 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 a p2mp MEG that is considered to be the set of MEs between the root
and each individual destination MEP. and each individual destination MEP.
2.2.3. 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
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function can be applied proactively or on-demand. 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.
2.2.6. Failures 2.2.6. Failures
The terms Failure, Fault, and Defect are used interchangeably 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
802.1ag], there is no distinction between these terms, while in other [IEEE802.1ag], there is no distinction between these terms, while in
standards each of these terms refers to a different type of other standards each of these terms refers to a different type of
malfunction. malfunction.
The terminology used in IETF MPLS-TP OAM takes after the ITU-T, which The terminology used in IETF MPLS-TP OAM takes after the ITU-T, which
distinguishes between these terms in [ITU-T-G.806]; The term Fault distinguishes between these terms in [ITU-T-G.806]; The term Fault
refers to an inability to perform a required action, e.g., an refers to an inability to perform a required action, e.g., an
unsuccessful attempt to deliver a packet. The term Defect refers to unsuccessful attempt to deliver a packet. The term Defect refers to
an interruption in the normal operation, such as a consecutive period an interruption in the normal operation, such as a consecutive period
of time where no packets are delivered successfully. The term Failure of time where no packets are delivered successfully. The term Failure
refers to the termination of the required function. While a Defect refers to the termination of the required function. While a Defect
typically refers to a limited period of time, a failure refers to a typically refers to a limited period of time, a failure refers to a
long period of time. long period of time.
3. OAM Tools 3. OAM Tools
3.1. ICMP Ping 3.1. IP Ping and Traceroute
ICMP provides a connectivity verification function for the Internet 3.1.1. Ping
Protocol. The originator transmits an ICMP Echo request packet, and
the receiver replies with an echo reply. ICMP ping is defined in two
variants, [ICMPv4] is used for IPv4, and [ICMPv6] is used for IPv6.
3.2. Traceroute Ping is a common network diagnosis application for IP networks that
uses ICMP. The ICMP Echo request/reply exchange is a connectivity
verification function for the Internet Protocol. The originator
transmits an ICMP Echo request packet, and the receiver replies with
an Echo reply. ICMP ping is defined in two variants, [ICMPv4] is used
for IPv4, and [ICMPv6] is used for IPv6.
Traceroute ([TCPIP-Tools]) is an application that allows users to 3.1.2. Traceroute
discover the path between an IP source and an IP destination.
Traceroute sends a sequence of UDP packets to UDP port 33434 at the
destination. By default, Traceroute begins by sending three packets,
each with an IP Time-To-Live (TTL) value of one to the destination.
These packets expire as soon as they reach the first router in the Traceroute ([TCPIP-Tools], [NetTools]) is an application that allows
path. That router responds by sending three ICMP Time Exceeded users to discover the path between an IP source and an IP
Messages to the Traceroute application. Traceroute now sends another destination. Traceroute sends a sequence of UDP packets to UDP port
three UDP packets, each with the TTL value of 2. These messages cause 33434 at the destination. By default, Traceroute begins by sending
the second router to return ICMP messages. This process continues, three packets (the number of packets is configurable in most
with ever increasing values for the TTL field, until the packets Traceroute implementations), each with an IP Time-To-Live (TTL) value
actually reach the destination. Because no application listens to of one to the destination. These packets expire as soon as they reach
port 33434 at the destination, the destination returns ICMP the first router in the path. That router responds by sending three
Destination Unreachable Messages indicating an unreachable port. This ICMP Time Exceeded Messages to the Traceroute application. Traceroute
event indicates to the Traceroute application that it is finished. now sends another three UDP packets, each with the TTL value of 2.
The Traceroute program displays the round-trip delay associated with These messages cause the second router to return ICMP messages. This
each of the attempts. 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.
Note that IP routing may be asymmetric. While Traceroute reveals the Note that IP routing may be asymmetric. While Traceroute reveals the
path between a source and destination, it may not reveal the reverse path between a source and destination, it may not reveal the reverse
path. path.
3.3. Bidirectional Forwarding Detection (BFD) A few ICMP extensions ([ICMP-Ext], [ICMP-MP], [ICMP-Int]) have been
defined in the context of Traceroute. These extensions augment the
ICMP Destination Unreachable message, and can be used by Traceroute
applications.
3.3.1. Overview 3.2. Bidirectional Forwarding Detection (BFD)
3.2.1. 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],
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]. The usage of BFD in MPLS-TP is defined in [MPLS-TP-CC- [BFD-VCCV]. The usage of BFD in MPLS-TP is defined in [MPLS-TP-CC-
CV]. 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.
3.3.2. BFD Control 3.2.2. 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 (i.e. proactive): in this mode BFD control o Asynchronous mode (i.e. proactive): in this mode BFD control
packets are sent periodically. When the receiver detects that no packets are sent periodically. When the receiver detects that no
BFD control packet have been received during a predetermined BFD control packet have been received during a predetermined
period of time, a failure is detected. period of time, a failure is detected.
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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.
3.3.3. BFD Echo 3.2.3. BFD Echo
A BFD echo packet is sent to a peer system, and is looped back to the A BFD echo packet is sent to a peer system, and is looped back to the
originator. The echo function can be used proactively, or on-demand. originator. The echo function can be used proactively, or on-demand.
The BFD echo function has been defined in BFD for IPv4 and IPv6 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 ([BFD-IP]), but is not used in BFD for MPLS LSPs, PWs, or in BFD for
MPLS-TP. MPLS-TP.
3.4. LSP Ping 3.3. MPLS OAM
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 are 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
skipping to change at page 16, line 25 skipping to change at page 19, line 16
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. activation.
3.5. PWE3 Virtual Circuit Connectivity Verification (VCCV) 3.4. MPLS-TP OAM
VCCV, as defined in [VCCV], provides a means for end-to-end fault
detection and diagnostics tools to be extended for PWs (regardless of
the underlying tunneling technology). The VCCV switching function
provides a control channel associated with each PW (based on the PW
Associated Channel Header (ACH) which is defined in [PW-ACH]), and
allows transmitting the OAM packets in-band with PW data (using CC
Type 1: In-band VCCV).
VCCV currently supports the following OAM mechanisms: ICMP Ping, LSP
Ping, and BFD. ICMP and LSP Ping are IP encapsulated before being
sent over the PW ACH. BFD for VCCV supports two modes of
encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
PW-ACH encapsulated (with no IP/UDP header) and provides support to
signal the AC status. The use of the VCCV control channel provides
the context, based on the MPLS-PW label, required to bind and
bootstrap the BFD session to a particular pseudo wire (FEC),
eliminating the need to exchange Discriminator values.
VCCV consists of two components: (1) signaled component to
communicate VCCV capabilities as part of VC label, and (2) switching
component to cause the PW payload to be treated as a control packet.
VCCV is not directly dependent upon the presence of a control plane.
The VCCV capability negotiation may be performed as part of the PW
signaling when LDP is used. In case of manual configuration of the
PW, it is the responsibility of the operator to set consistent
options at both ends.
3.6. IP Performance Metrics (IPPM)
3.6.1. Overview
The IPPM working group in the IETF defines common criteria and
metrics for measuring performance of IP traffic ([IPPM-FW]). Some of
the key RFCs published by this working group have defined metrics for
measuring connectivity [IPPM-Con], delay ([IPPM-1DM], [IPPM-2DM]),
and packet loss [IPPM-1LM].
Alternative protocols for performance measurement are defined, for
example, in MPLS-TP OAM ([MPLS-LM-DM], [TP-LM-DM]), and in Ethernet
OAM [ITU-T-Y.1731].
The IPPM working group has defined not only metrics for performance
measurement, but also protocols that define how the measurement is
carried out. The One-way Active Measurement Protocol [OWAMP] and the
Two-Way Active Measurement Protocol [TWAMP] define a method and
protocol for measuring delay and packet loss in IP networks.
OWAMP [OWAMP] enables measurement of one-way characteristics of IP
networks, such as one-way packet loss and one-way delay. For its
proper operation OWAMP requires accurate time of day setting at its
end points.
TWAMP [TWAMP] is a similar protocol that enables measurement of two-
way (round trip) characteristics. TWAMP does not require accurate
time of day, and, furthermore, allows the use of a simple session
reflector, making it an attractive alternative to OWAMP.
OWAMP and TWAMP use two separate protocols: a Control plane protocol,
and a Test plane protocol.
3.6.2. Control and Test Protocols
OWAMP and TWAMP control protocols run over TCP, while the test
protocols run over UDP. The purpose of the control protocols is to
initiate, start, and stop test sessions, and for OWAMP to fetch
results. The test protocols introduce test packets (which contain
sequence numbers and timestamps) along the IP path under test
according to a schedule, and record statistics of packet arrival.
Multiple sessions may be simultaneously defined, each with a session
identifier, and defining the number of packets to be sent, the amount
of padding to be added (and thus the packet size), the start time,
and the send schedule (which can be either a constant time between
test packets or exponentially distributed pseudo-random). Statistics
recorded conform to the relevant IPPM RFCs.
OWAMP and TWAMP test traffic is designed with security in mind. Test
packets are hard to detect because they are simply UDP streams
between negotiated port numbers, with potentially nothing static in
the packets. OWAMP and TWAMP also include optional authentication
and encryption for both control and test packets.
3.6.3. OWAMP
OWAMP defines the following logical roles: Session-Sender, Session-
Receiver, Server, Control-Client, and Fetch-Client. The Session-
Sender originates test traffic that is received by the Session-
Receiver. The Server configures and manages the session, as well as
returning the results. The Control-Client initiates requests for
test sessions, triggers their start, and may trigger their
termination. The Fetch-Client requests the results of a completed
session. Multiple roles may be combined in a single host - for
example, one host may play the roles of Control-Client, Fetch-Client,
and Session-Sender, and a second playing the roles of Server and
Session-Receiver.
In a typical OWAMP session the Control-Client establishes a TCP
connection to port 861 of the Server, which responds with a server
greeting message indicating supported security/integrity modes. The
Control-Client responds with the chosen communications mode and the
Server accepts the modes. The Control-Client then requests and fully
describes a test session to which the Server responds with its
acceptance and supporting information. More than one test session
may be requested with additional messages. The Control-Client then
starts a test session and the Server acknowledges. The Session-
Sender then sends test packets with pseudorandom padding to the
Session-Receiver until the session is complete or until the Control-
client stops the session. Once finished, the Fetch-Client sends a
fetch request to the server, which responds with an acknowledgement
and immediately thereafter the result data.
3.6.4. TWAMP
TWAMP defines the following logical roles: session-sender, session-
reflector, server, and control-client. These are similar to the
OWAMP roles, except that the Session-Reflector does not collect any
packet information, and there is no need for a Fetch-Client.
In a typical TWAMP session the Control-Client establishes a TCP
connection to port 862 of the Server, and mode is negotiated as in
OWAMP. The Control-Client then requests sessions and starts them.
The Session-Sender sends test packets with pseudorandom padding to
the Session-Reflector which returns them with insertion of
timestamps.
3.7. MPLS-TP OAM
3.7.1. Overview 3.4.1. 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 fulfills 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 [TP-OAM-FW], which describes the general architecture of the OAM in [TP-OAM-FW], which describes the general architecture of the OAM
system as well as giving overviews of the functionality of the OAM system as well as giving overviews of the functionality of the OAM
toolset. toolset.
skipping to change at page 19, line 43 skipping to change at page 19, line 47
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.
3.7.2. Generic Associated Channel 3.4.2. 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 prepended 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 (13) that indicates that the packet is an ACH packet and the value (13) that indicates that the packet is an ACH packet and the
payload follows immediately after the label stack. payload follows immediately after the label stack.
3.7.3. MPLS-TP OAM Toolset 3.4.3. 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-Analys]. The
The MPLS working group currently plans to use a mixture of OAM MPLS working group currently plans to use a mixture of OAM mechanisms
mechanisms that are based on various existing standards, and adapt that are based on various existing standards, and adapt them to the
them to the requirements of [MPLS-TP-OAM]. Some of the main building requirements of [MPLS-TP-OAM]. Some of the main building blocks of
blocks of this solution are based on: this solution are based on:
o Bidirectional Forwarding Detection ([BFD], [BFD-LSP]) for o Bidirectional Forwarding Detection ([BFD], [BFD-LSP]) for
proactive continuity check and connectivity verification. proactive continuity check and connectivity verification.
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-Y1731].
The following sub-sections describe the OAM tools defined for MPLS-TP The following sub-sections describe the OAM tools defined for MPLS-TP
as described in [TP-OAM-FW]. as described in [TP-OAM-FW].
3.7.3.1. Continuity Check and Connectivity Verification 3.4.3.1. Continuity Check and Connectivity Verification
Continuity Check and Connectivity Verification are presented in Continuity Check and Connectivity Verification are presented in
Section 2.2.5 of this document. As presented there, these tools may Section 2.2.5. of this document. As presented there, these tools may
be used either proactively or on-demand. When using these tools be used either proactively or on-demand. When using these tools
proactively, they are generally used in tandem. proactively, they are generally used in tandem.
For MPLS-TP there are two distinct tools, the proactive tool is 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 defined in [TP-CC-CV] while the on-demand tool is defined in
[OnDemand-CV].Proactively [MPLS-TP-OAM] states that the function [OnDemand-CV].Proactively [MPLS-TP-OAM] states that the function
should allow the MEPs to monitor the liveness and connectivity of a should allow the MEPs to monitor the liveness and connectivity of a
transport path. In on-demand mode, this function should support transport path. In on-demand mode, this function should support
monitoring between the MEPs and, in addition, between a MEP and MIP. monitoring between the MEPs and, in addition, between a MEP and MIP.
[TP-OAM-FW] highlights, when performing Connectivity Verification, [TP-OAM-FW] highlights, when performing Connectivity Verification,
the need for the CC-V messages to include unique identification of the need for the CC-V messages to include unique identification of
the MEG that is being monitored and the MEP that originated the the MEG that is being monitored and the MEP that originated the
message. message.
The proactive tool [MPLS-TP-CC-CV] is based on extensions to BFD (see The proactive tool [TP-CC-CV] is based on extensions to BFD (see
Section 3.3) with the additional limitation that the transmission and Section 3.2. ) with the additional limitation that the transmission
receiving rates are based on configuration by the operator. The on- and receiving rates are based on configuration by the operator. The
demand tool [OnDemand-CV] is an adaptation of LSP Ping (See Section on-demand tool [OnDemand-CV] is an adaptation of LSP Ping (see
3.4) for the required behavior of MPLS-TP. Section 3.3. ) for the required behavior of MPLS-TP.
3.7.3.2. Route Tracing 3.4.3.2. 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. The tool for this is based on the LSP Ping (See return path exists. The tool for this is based on the LSP Ping (see
Section 3.4) functionality and is described in [OnDemand-CV]. Section 3.3. ) functionality and is described in [OnDemand-CV].
3.7.3.3. Lock Instruct 3.4.3.3. Lock Instruct
The Lock Instruct function is used to notify a transport path end- The Lock Instruct function [Lock-Loop] is used to notify a transport
point of an administrative need to disable the transport path. This path end-point of an administrative need to disable the transport
functionality will generally be used in conjunction with some path. This functionality will generally be used in conjunction with
intrusive OAM function, e.g. Performance measurement, Diagnostic some 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.
3.7.3.4. Lock Reporting 3.4.3.4. 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.
3.7.3.5. Alarm Reporting 3.4.3.5. 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. [TP-OAM-FW] states that this may occur as a end-points of the path. [TP-OAM-FW] states that this may occur as a
result of a defect condition discovered at a server sub-layer. This result of a defect condition discovered at a server sub-layer. This
generates an Alarm Indication Signal (AIS) that continues until the generates an Alarm Indication Signal (AIS) that continues until the
fault is cleared. The consequent action of this function is detailed fault is cleared. The consequent action of this function is detailed
in [TP-OAM-FW]. in [TP-OAM-FW].
3.7.3.6. Remote Defect Indication 3.4.3.6. 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. [TP-OAM-FW] points out that this function is return path exists. [TP-OAM-FW] points out that this function is
associated with the proactive CC-V function. associated with the proactive CC-V function.
3.7.3.7. Client Failure Indication 3.4.3.7. 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.
3.7.3.8. Packet Loss Measurement 3.4.3.8. Packet Loss Measurement (LM)
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.
3.7.3.9. Packet Delay Measurement 3.4.3.9. Packet Delay Measurement (DM)
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.
3.8. Summary of OAM Functions 3.5. PWE3 OAM
3.5.1. PWE3 OAM using Virtual Circuit Connectivity Verification (VCCV)
VCCV, as defined in [VCCV], provides a means for end-to-end fault
detection and diagnostics tools to be extended for PWs (regardless of
the underlying tunneling technology). The VCCV switching function
provides a control channel associated with each PW (based on the PW
Associated Channel Header (ACH) which is defined in [PW-ACH]), and
allows transmitting the OAM packets in-band with PW data (using CC
Type 1: In-band VCCV).
VCCV currently supports the following OAM mechanisms: ICMP Ping, LSP
Ping, and BFD. ICMP and LSP Ping are IP encapsulated before being
sent over the PW ACH. BFD for VCCV [BFD-VCCV] supports two modes of
encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
PW-ACH encapsulated (with no IP/UDP header) and provides support to
signal the AC status. The use of the VCCV control channel provides
the context, based on the MPLS-PW label, required to bind and
bootstrap the BFD session to a particular pseudo wire (FEC),
eliminating the need to exchange Discriminator values.
VCCV consists of two components: (1) signaled component to
communicate VCCV capabilities as part of VC label, and (2) switching
component to cause the PW payload to be treated as a control packet.
VCCV is not directly dependent upon the presence of a control plane.
The VCCV capability negotiation may be performed as part of the PW
signaling when LDP is used. In case of manual configuration of the
PW, it is the responsibility of the operator to set consistent
options at both ends.
3.5.2. PWE3 OAM using G-ACh
As mentioned above, VCCV enables OAM for PWs by using a control
channel for OAM packets. When PWs are used in MPLS-TP networks,
rather than the control channels defined in VCCV, the G-ACh can be
used as an alternative control channel. The usage of the G-ACh for
PWs is defined in [PW-G-ACh].
3.6. OWAMP and TWAMP
3.6.1. Overview
The IPPM working group in the IETF defines common criteria and
metrics for measuring performance of IP traffic ([IPPM-FW]). Some of
the key RFCs published by this working group have defined metrics for
measuring connectivity [IPPM-Con], delay ([IPPM-1DM], [IPPM-2DM]),
and packet loss [IPPM-1LM].
Alternative protocols for performance measurement are defined, for
example, in MPLS-TP OAM ([MPLS-LM-DM], [TP-LM-DM]), and in Ethernet
OAM [ITU-T-Y1731].
The IPPM working group has defined not only metrics for performance
measurement, but also protocols that define how the measurement is
carried out. The One-way Active Measurement Protocol [OWAMP] and the
Two-Way Active Measurement Protocol [TWAMP] define a method and
protocol for measuring delay and packet loss in IP networks.
OWAMP [OWAMP] enables measurement of one-way characteristics of IP
networks, such as one-way packet loss and one-way delay. For its
proper operation OWAMP requires accurate time of day setting at its
end points.
TWAMP [TWAMP] is a similar protocol that enables measurement of two-
way (round trip) characteristics. TWAMP does not require accurate
time of day, and, furthermore, allows the use of a simple session
reflector, making it an attractive alternative to OWAMP.
OWAMP and TWAMP use two separate protocols: a Control plane protocol,
and a Test plane protocol.
3.6.2. Control and Test Protocols
OWAMP and TWAMP control protocols run over TCP, while the test
protocols run over UDP. The purpose of the control protocols is to
initiate, start, and stop test sessions, and for OWAMP to fetch
results. The test protocols introduce test packets (which contain
sequence numbers and timestamps) along the IP path under test
according to a schedule, and record statistics of packet arrival.
Multiple sessions may be simultaneously defined, each with a session
identifier, and defining the number of packets to be sent, the amount
of padding to be added (and thus the packet size), the start time,
and the send schedule (which can be either a constant time between
test packets or exponentially distributed pseudo-random). Statistics
recorded conform to the relevant IPPM RFCs.
OWAMP and TWAMP test traffic is designed with security in mind. Test
packets are hard to detect because they are simply UDP streams
between negotiated port numbers, with potentially nothing static in
the packets. OWAMP and TWAMP also include optional authentication
and encryption for both control and test packets.
3.6.3. OWAMP
OWAMP defines the following logical roles: Session-Sender, Session-
Receiver, Server, Control-Client, and Fetch-Client. The Session-
Sender originates test traffic that is received by the Session-
Receiver. The Server configures and manages the session, as well as
returning the results. The Control-Client initiates requests for
test sessions, triggers their start, and may trigger their
termination. The Fetch-Client requests the results of a completed
session. Multiple roles may be combined in a single host - for
example, one host may play the roles of Control-Client, Fetch-Client,
and Session-Sender, and a second playing the roles of Server and
Session-Receiver.
In a typical OWAMP session the Control-Client establishes a TCP
connection to port 861 of the Server, which responds with a server
greeting message indicating supported security/integrity modes. The
Control-Client responds with the chosen communications mode and the
Server accepts the modes. The Control-Client then requests and fully
describes a test session to which the Server responds with its
acceptance and supporting information. More than one test session
may be requested with additional messages. The Control-Client then
starts a test session and the Server acknowledges. The Session-
Sender then sends test packets with pseudorandom padding to the
Session-Receiver until the session is complete or until the Control-
client stops the session. Once finished, the Fetch-Client sends a
fetch request to the server, which responds with an acknowledgement
and immediately thereafter the result data.
3.6.4. TWAMP
TWAMP defines the following logical roles: session-sender, session-
reflector, server, and control-client. These are similar to the
OWAMP roles, except that the Session-Reflector does not collect any
packet information, and there is no need for a Fetch-Client.
In a typical TWAMP session the Control-Client establishes a TCP
connection to port 862 of the Server, and mode is negotiated as in
OWAMP. The Control-Client then requests sessions and starts them.
The Session-Sender sends test packets with pseudorandom padding to
the Session-Reflector which returns them with insertion of
timestamps.
3.7. Summary of OAM Functions
Table 3 summarizes the OAM functions that are supported in each of Table 3 summarizes the OAM functions that are supported in each of
the standards that were analyzed in this section. the categories 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 | | | | | |IP Ping | |Echo | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|Traceroute | | |Tracerou| | | | |IP | | |Tracerou| | | |
| | | |te | | | | |Traceroute | | |te | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|BFD |BFD |BFD | | | | | |BFD |BFD |BFD | | | | |
| |Control|Echo | | | | | | |Control|Echo | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|LSP Ping | |"Ping" |"Tracero| | | | |MPLS OAM | |"Ping" |"Tracero| | | |
| | |mode |ute" | | | | |(LSP Ping) | |mode |ute" | | | |
| | | |mode | | | | | | | |mode | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ + + --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|IPPM | | | | |-Delay | |
| | | | | | measur| |
| | | | | | ement | |
| | | | | |-Packet| |
| | | | | | loss | |
| | | | | | measur| |
| | | | | | ement | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|MPLS-TP |CC |CV/pro- |Route |-Alarm |-LM |-Diagnos| |MPLS-TP |CC |CV/pro- |Route |-Alarm |-LM |-Diagnos|
|OAM | |active |Tracing | Reporting |-DM | tic Tes| |OAM | |active |Tracing | Reporting |-DM | tic Tes|
| | |or on- | |-Client | | t | | | |or on- | |-Client | | t |
| | |demand | | Failure | |-Lock | | | |demand | | Failure | |-Lock |
| | | | | Indication| | | | | | | | Indication| | |
| | | | |-Remote | | | | | | | |-Remote | | |
| | | | | Defect | | | | | | | | Defect | | |
| | | | | Indication| | | | | | | | Indication| | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|PWE3 OAM |BFD |-BFD |LSP-Ping| | | |
| | |-ICMP | | | | |
| | | Ping | | | | |
| | |-LSP- | | | | |
| | | Ping | | | | |
+ --------- + ----- + ------ + ------ + --------- + ----- + ------ +
|OWAMP and | | | | |-Delay | |
|TWAMP | | | | | measur| |
| | | | | | ement | |
| | | | | |-Packet| |
| | | | | | loss | |
| | | | | | measur| |
| | | | | | ement | |
+-----------+-------+--------+--------+-----------+-------+--------+ +-----------+-------+--------+--------+-----------+-------+--------+
Table 3 Summary of OAM Functions Table 3 Summary of OAM Functions
4. Security Considerations 4. Security Considerations
This memo presents an overview of existing OAM mechanisms, and This memo presents an overview of existing OAM mechanisms, and
proposes no new OAM mechanisms. Therefore, this document introduces proposes no new OAM mechanisms. Therefore, this document introduces
no security considerations. However, the OAM mechanism reviewed in no security considerations. However, the OAM mechanism reviewed in
this document can and do present security issues. The reader is this document can and do present security issues. The reader is
encouraged to review the Security Considerations section of each encouraged to review the Security Considerations section of each
document reference by this memo. document reference by this memo.
5. 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.
6. Acknowledgments 6. Acknowledgments
The authors gratefully acknowledge Sasha Vainshtein, Carlos
Pignataro, David Harrington, Dan Romascanu, Ron Bonica and other
members of the OPSAWG mailing list for their helpful comments.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
7. References 7. References
7.1. 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.,
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.
[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)
skipping to change at page 25, line 26 skipping to change at page 28, line 48
"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.
[MPLS-P2MP] Yasukawa, S., Farrel, A., King, D., Nadeau, T.,
"Operations and Management (OAM) Requirements for
Point-to-Multipoint MPLS Networks", RFC 4687,
September 2006.
[ICMP-Ext] Bonica, R., Gan, D., Tappan, D., Pignataro, C., "ICMP
Extensions for Multiprotocol Label Switching", RFC
4950, August 2007.
[ICMP-MP] Bonica, R., Gan, D., Tappan, D., Pignataro, C.,
"Extended ICMP to Support Multi-Part Messages", RFC
4884, April 2007.
[ICMP-Int] Atlas, A., Bonica, R., Pignataro, C., Shen, N., Rivers,
JR., "Extending ICMP for Interface and Next-Hop
Identification", RFC 5837, April 2010.
[TCPIP-Tools] Kessler, G., Shepard, S., "A Primer On Internet and [TCPIP-Tools] Kessler, G., Shepard, S., "A Primer On Internet and
TCP/IP Tools and Utilities", RFC 2151, June 1997. TCP/IP Tools and Utilities", RFC 2151, June 1997.
[NetTools] Stine, R., "FYI on a Network Management Tool Catalog:
Tools for Monitoring and Debugging TCP/IP Internets
and Interconnected Devices", RFC 1147, April 1990.
[IPPM-FW] Paxson, V., Almes, G., Mahdavi, J., and Mathis, M., [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 26, line 36 skipping to change at page 30, line 29
[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.
[TP-OAM-FW] Busi, I., Allan, D., "Operations, Administration and [TP-OAM-FW] Busi, I., Allan, D., "Operations, Administration and
Maintenance Framework for MPLS-based Transport Maintenance Framework for MPLS-based Transport
Networks ", RFC 6371, September 2011. Networks ", RFC 6371, September 2011.
[MPLS-TP-CC-CV] Allan, D., Swallow, G., Drake, J., "Proactive [TP-CC-CV] Allan, D., Swallow, G., Drake, J., "Proactive
Connectivity Verification, Continuity Check and Remote Connectivity Verification, Continuity Check and Remote
Defect indication for MPLS Transport Profile", RFC Defect indication for MPLS Transport Profile", RFC
6428, November 2011. 6428, November 2011.
[OnDemand-CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS [OnDemand-CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS
On-Demand Connectivity Verification and Route On-Demand Connectivity Verification and Route
Tracing", RFC 6426, November 2011. Tracing", RFC 6426, November 2011.
[MPLS-LM-DM] Frost, D., Bryant, S., "Packet Loss and Delay [MPLS-LM-DM] Frost, D., Bryant, S., "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374, September Measurement for MPLS Networks", RFC 6374, September
2011. 2011.
[TP-LM-DM] Frost, D., Bryant, S., "A Packet Loss and Delay [TP-LM-DM] Frost, D., Bryant, S., "A Packet Loss and Delay
Measurement Profile for MPLS-Based Transport Measurement Profile for MPLS-Based Transport
Networks", RFC 6375, September 2011. Networks", RFC 6375, September 2011.
[MPLS-TP-Fault] Swallow, G., Fulignoli, A., Vigoureux, M., Boutros, [TP-Fault] Swallow, G., Fulignoli, A., Vigoureux, M., Boutros, S.,
S., "MPLS Fault Management Operations, Administration, "MPLS Fault Management Operations, Administration, and
and Maintenance (OAM)", RFC 6427, November 2011. Maintenance (OAM)", RFC 6427, November 2011.
[TP-Lock-Loop] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux, [Lock-Loop] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux,
M., Dai, X., "MPLS Transport Profile Lock Instruct and M., Dai, X., "MPLS Transport Profile Lock Instruct and
Loopback Functions", RFC 6435, November 2011. Loopback Functions", RFC 6435, November 2011.
[ITU-T-CT] Betts, M., "Allocation of a Generic Associated Channel
Type for ITU-T MPLS Transport Profile Operation,
Maintenance, and Administration (MPLS-TP OAM)", RFC
6671, November 2012.
[PW-Map] M. Aissaoui, P. Busschbach, L. Martini, M. Morrow, T.
Nadeau, "Pseudowire (PW) Operations, Administration,
and Maintenance (OAM) Message Mapping", RFC 6310, July
2011.
[PW-G-ACh] Li, H., Martini, L., He, J., Huang, F., "Using the
Generic Associated Channel Label for Pseudowire in the
MPLS Transport Profile (MPLS-TP)", RFC 6423, November
2011.
7.2. Informative References 7.2. Informative References
[OAM-Def] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu, [OAM-Def] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu,
D., Mansfield, S., "Guidelines for the use of the OAM D., Mansfield, S., "Guidelines for the use of the OAM
acronym in the IETF ", RFC 6291, June 2011. acronym in the IETF ", RFC 6291, June 2011.
[OAM-Analysis]Sprecher, N., Fang, L., "An Overview of the OAM Tool [OAM-Analys] Sprecher, N., Fang, L., "An Overview of the OAM Tool
Set for MPLS based Transport Networks", RFC 6669, Set for MPLS based Transport Networks", RFC 6669,
July 2012. July 2012.
[MPLS-TP-Term]Van Helvoort, H., Andersson, L., Sprecher, N., "A [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, January 2012. tp-rosetta-stone, July 2012.
[IEEE-802.1ag]"Connectivity Fault Management", December 2007. [IEEE802.1ag] IEEE 802.1Q, "IEEE Standard for Local and metropolitan
area networks - Media Access Control (MAC) Bridges and
Virtual Bridged Local Area Networks", October 2012.
[ITU-T-Y.1731]"OAM Functions and Mechanisms for Ethernet-based [ITU-T-Y1731] ITU-T Recommendation G.8013/Y.1731, "OAM Functions and
Networks", February 2008. Mechanisms for Ethernet-based Networks", July 2011.
[ITU-T-Y.1711]"Operation & Maintenance mechanism for MPLS networks", [ITU-T-Y1711] ITU-T Recommendation Y.1711, "Operation & Maintenance
February 2004. mechanism for MPLS networks", February 2004.
[IEEE-802.3ah]"Media Access Control Parameters, Physical Layers, and [IEEE802.3ah] IEEE 802.3, "IEEE Standard for Information technology -
Management Parameters for Subscriber Access Networks", Local and metropolitan area networks - Carrier sense
clause 57, September 2004. multiple access with collision detection (CSMA/CD)
access method and physical layer specifications",
clause 57, December 2008.
[ITU-T-G.806] "Characteristics of transport equipment - Description [ITU-T-G.806] ITU-T Recommendation G.806, "Characteristics of
methodology and generic functionality", January, 2009. transport equipment - Description methodology and
generic functionality", January 2009.
[ITU-G8113.2] ITU-T Recommendation G.8113.2/Y.1372.2, "Operations,
administration and maintenance mechanisms for MPLS-TP
networks using the tools defined for MPLS", November
2012.
[ITU-G8113.1] ITU-T Recommendation G.8113.1/Y.1372.1, "Operations,
Administration and Maintenance mechanism for MPLS-TP
in Packet Transport Network (PTN)", November 2012.
Authors' Addresses 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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