IDR Working Group Y. Tochio
Internet-Draft Fujitsu
Intended status: Standards Track H. van Helvoort
Expires: March 30, 2015 Hai Gaoming BV
L. Xia
Huawei
September 26, 2014
Gap Analysis for Layer and Technology Independent OAM Management in the
Multi-Layer Environment
draft-txh-opsawg-lime-gap-analysis-00
Abstract
This draft analyses the existing management plane OAM related works
in different SDOs, against the key objectives of Layer Independent
OAM Management (LIME), to find the gap between them. The results can
be used as the guidance for further work.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Existing OAM Related Works . . . . . . . . . . . . . . . . . 4
3.1. Management Information Models . . . . . . . . . . . . . . 5
3.2. IEEE CFM MIB . . . . . . . . . . . . . . . . . . . . . . 6
3.3. MEF SOAM FM and PM MIB . . . . . . . . . . . . . . . . . 6
3.4. IETF Technology-specific MIB Series . . . . . . . . . . . 7
3.5. MEF CFM and SOAM YANG Data Model . . . . . . . . . . . . 7
3.6. YANG Model for OAM Management and Technology-specific
extensions . . . . . . . . . . . . . . . . . . . . . . . 7
3.7. Discussion . . . . . . . . . . . . . . . . . . . . . . . 8
3.7.1. Consolidation in the Management Plane . . . . . . . . 8
3.7.2. A Generic and Reusable OAM Data Model . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Operations, Administration, and Maintenance (OAM) mechanisms are
critical building blocks in network operations that are used for
service assurance, fulfillment, or service diagnosis,
troubleshooting, and repair. The current practice is maintenance and
troubleshooting are achieved per technology and per layer. The
operation process can be very cumbersome.
Due to this fact, [LIME-PS] discusses a valuable direction in
management plane by consolidating OAM information from each layer
using centralized management entity and have a unified and consistent
OAM view of multi-layer network. Operators can rely on consolidated
OAM management to correlate different layer OAM information (e.g.,
fault, defects and network failure), and quickly identify the faulty
element with its layer information in the network path. The second
important objective of LIME is to achieve a layer and technology
independent OAM view of network and allow management application
present to the user an abstract view of this network and its
supporting layers that is strictly topological, free of any
technology specific information. This means an abstract and generic
OAM management model in management plane should be developed firstly,
and then any technology-specific OAM data model can be developed by
extending and inheriting from it. Generic OAM management model can
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provide a consistent configuration, reporting, and presentation for
the OAM mechanisms. It also can mitigate the problem related to
specific OAM technology dependency. [LIME-UC] lists the key use case
for LIME application.
This draft analyses the existing management plane OAM related works
in several SDOs, against the key objectives of LIME, to find the gap
between them. The results can be used as the guidance for further
work.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
2.1. Terminology
DM Data Model
EMS Element Management System [G.8052]
IM Information Model
NMS Network Management System [G.8052]
MP Maintenance Point [802.1Q]
MEP Maintenance Entity Group End Point [Y.1731] [RFC6371]
MIP Maintenance Entity Group Intermediate Point [Y.1731] [RFC6371]
MEG Maintenance Entity Group [Y.1731] [RFC6371]
ME Maintenance Entity [Y.1731] [RFC6371]
MD Maintenance Domain [802.1Q]
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MPLS Multiprotocol Label Switching
NE Network Element
NVO3 Network Virtualization Overlays
OAM Operations, Administration, and Maintenance [RFC6291]
LIME Layer Independent OAM Management [LIME-PS]
SF Service Function Chaining
SFF Service Function Forwarder
SDO Standard Developing Organization
3. Existing OAM Related Works
Two objectives of LIME are:
o Consolidated OAM Management
o Layer and technology independent OAM Management
To achieve these two objectives and accelerate Yang data model
development, we can use Existing Information model in ITU-T and MEF,
OAM MIB Module and CFM model as basis and directly develop Yang Data
model.
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+---------------+ +---------------+ +----------+
| Existing IM | | OAM MIB Module| | CFM Model|
| in MEF, ITU-T | | (IETF, IEEE, | | Y.1731 |
| (e.g.,MEF 7.1 | | MEF) | | |
| ITU-T G.8052) | +-------|-------+ +-----|----+
+--------|------+ | |
| | |
-------------------|------------------|
+-----------------+
| Yang Data Model |
|for OAM Management
+------+----------+
| Augument/Inherit
+---------+-------------+
|Specific technology OAM|
| Data Model |
+-----------------------+
Yang Data Model Development
Following are the detailed surveys for the existing management plane
OAM works.
3.1. Management Information Models
ITU-T's Recommendation [G.8052] and [G.8152] provide the management
protocol-neutral information models for managing network elements in
the Ethernet transport network and MPLS-TP transport network as
defined in Recommendations [G.8010] and [G.8110.1] respectively.
They contain the object classes for the Ethernet and MPLS-TP NE
management. It includes the Termination Points (TP), Maintenance
Entity Group (MEG) End Point (MEP), MEG Intermediate Point (MIP),
Traffic Conditioning & Shaping (TCS), Loss Measurement (LM), Delay
Measurement (DM), and the general Performance Monitoring (PM) Current
Data (CD) and History Data (HD). [G.8052] has been published.
[G.8152] is still in progress.
[MEF-7.1] specifies the EMS-NMS interface profile identifying the
managed objects (i.e. logical UML objects) needed to support Metro
Ethernet services. This specification provides the profile of
management entities based on ITU-T [Q.840.1], and also provides a
mapping to the TMF's MTNM 3.5 Ethernet model. Specifically this
document adds management support for Service OAM. The Ethernet
Service OAM object definitions include common OAM objects (e.g.,
EthMe, EthMeg, EthMep, EthMip, EthMp, EthMd, EthMepPeerInfo), Fault
Management Objects (e.g., Continuity Check, Loopback, Link Trace,
Signal Functions), Performance Monitoring Objects (e.g., Abstract
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Performance Monitoring Objects, Loss Measurement, Delay Measurement,
Function Sets).
The above OAM information models provide the baseline for the further
definitions of OAM MIB modules and OAM YANG model. But they are
still technology-specific definitions, not abstract and generic
enough.
3.2. IEEE CFM MIB
The IEEE8021-CFM-MIB MIB Module and IEEE8021-CFM-V2-MIB MIB module
are CFM MIB modules for managing IEEE CFM in [802.1Q]. The former
document defines all the MIB objects that used to read, create,
modify, and delete OAM related information (i.e., CFM Stack Table, MD
Table, MA Table, MEP Table, LinkTrace Reply Table, MEP DB Table,
Notifications Table, etc). The latter document defines CFM V2 module
for managing IEEE CFM. It contains objects that replace those
deprecated in the IEEE8021-CFM-MIB module (i.e., CFM Stack Table, CFM
Vlan Table, CFM Default MD Level Table, etc).
These CFM MIB modules defined for Ethernet network are the input for
analyzing what the generic OAM data model should be and have.
3.3. MEF SOAM FM and PM MIB
[MEF-31] defines the MIB modules for MEF Service OAM Fault Management
(FM). This document includes two MIBs necessary to support the MEF
SOAM FM functionality: the MEF-SOAM-TC-MIB that includes the Textual
Conventions (TC) for the SOAM MIB family and the MEF-SOAM-FM-MIB that
includes extensions to Connectivity Fault Management (CFM) as
developed in IEEE [802.1Q], including MIBs found in [IEEE 802.1Q] and
[IEEE 802.1ap], and enhanced by ITU-T [Y.1731] to support the SOAM FM
functions as presented in the [MEF-30] specification. It includes
the SOAM FM MIB objects such as mefSoamNet, mefSoamMeg, mefSoamMep,
mefSoamCc, mefSoamAis, mefSoamLb, etc.
[MEF-36] specifies the Performance Monitoring (PM) MIB necessary to
manage SOAM implementations that satisfy the Service OAM requirements
and framework specified by [MEF-17], the Service OAM Performance
Monitoring requirements as specified by [MEF-35], and the Service OAM
management objects as specified by [MEF-7.1] which are applicable to
Performance Monitoring functions. Two non-MEF documents serve as the
baseline documents for this work: ITU-T [Y.1731] and IEEE [802.1Q].
The SOAM PM MIB is divided into a number of different object
groupings: the PM MIB MEP Objects, PM MIB Loss Measurement Objects,
PM MIB Delay Measurement Objects, and SOAM PM Notifications.
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These documents' MIB definitions are also in the Ethernet layer and
are the input for the LIME works.
3.4. IETF Technology-specific MIB Series
IETF specifies a series MIB module for various technologies, which
includes: [RFC7331] for BFD MIB, [RFC4560] for PING MIB, [MPLS-TP OAM
ID MIB] for MPLS-TP MIB, etc.
All these documents are technology-specific and limited to layer
1/2/3. The OAM MIB definition above layer 3 (i.e., SFC service
layer) is still missing in IETF. Further study is needed to abstract
a unified and general OAM data model for any network layers from them
and other SDOs' OAM works.
3.5. MEF CFM and SOAM YANG Data Model
SOAM CFM YANG module [MEF-38] is an important work that defines the
managed objects necessary to support SOAM CFM functionality by using
the IETF YANG Module Language [RFC6020]. This YANG module contains
the management data definitions for the management of Ethernet
Services OAM for Connectivity Fault Management.
[MEF-39] provides the YANG module that supports the Ethernet Service
OAM (SOAM) Performance Monitoring functions. This YANG module
contains the management data definitions for the management of
Ethernet Services OAM for Performance Monitoring and extends the
Connectivity Fault Management (CFM) YANG modules.
These MEF OAM YANG works are important reference for the LIME works.
3.6. YANG Model for OAM Management and Technology-specific extensions
[I-D.tissa-netmod-oam] is an IETF work that creates a YANG unified
data model for OAM that is based on IEEE CFM model. This model may
be used also for IP OAM functionality. This effort is focused on the
management plane of OAM and should be complemented by an accompanying
data-plane and/or control-plane work. It may require also some
extensions to support wider variety of functions and technologies.
[I-D.tissa-nvo3-yang-oam] extends the Generic YANG model defined in
[I-D.tissa-netmod-oam] for OAM with NVO3 technology specifics and
presents Yang Module for NVO3 OAM.
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3.7. Discussion
Until now, all the OAM data models and operations in the management
plane are technology dependent and limited to one specific layer.
3.7.1. Consolidation in the Management Plane
Consolidation means here the management functions are capable of
receiving and reacting to related information from every transport
segment at every layer in the network. The reacting to related
information from every layer can include:
o Synthesize the OAM information from every layer;
o Exchange and correlation between the OAM information from every
layer;
o Orchestrating and coordinating the OAM operations among every
layer based on the above information for an end to end service.
However, there is little consolidation of OAM in management plane nor
well-documented inter-layer OAM operations within current MIB
definition works by IEEE, MEF or IETF, and YANG model definition work
by MEF. This also results in an end to end and service-level OAM
view of network is hardly generated in the management plane.
In addition to consolidation, a layer and technology independent OAM
view of network is also important for multi-layer OAM. The challenge
to get this view is to abstract in a way that retains in the
management plane as much useful information as possible while
filtering the data that is not needed to be leaked to layers in the
data plane. An important part of this effort is a clear
understanding of what information is actually needed. Current
existing OAM works in various SDOs do not consider this issue now.
3.7.2. A Generic and Reusable OAM Data Model
Another aspect is about the OAM data model specification. The
existing traditional implementations of data models in management
plane, such as MIB, YANG, are all technology-specific. They specify
the MIB module or YANG model for specific technology respectively.
There are many overlapping contents and repeated works during specify
data model for any technologies. The same condition happens each
time when a new technology needs to specify its own data model in
management plane.
So, a generic and reusable OAM data model is essential and valuable
for this kind of work. And to the extent that management operations
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are being redesigned in terms of YANG modules [RFC6020] over NETCONF
[RFC6241], the opportunity appears to use the concept of layer and
technology independent abstraction to extract the reusable parts,
simplifying the work on the remainder.
4. Security Considerations
TBD.
5. Normative References
[G.8052] "Protocol-neutral management information model for the
Ethernet transport capable network element", Draft
Recommendation ITU-T G.8052/Y.1346, August 2013.
[G.8110.1]
"Architecture of MPLS Transport Profile (MPLS-TP) layer
network", ITU-T G.8110.1/Y.1370.1, December 2011.
[G.8152] "Protocol-neutral management information model for the
MPLS-TP network element", Draft Recommendation ITU-T
G.8152/Y.1375, September 2015.
[I-D.tissa-netmod-oam]
Senevirathne, T., Finn, N., Kumar, D., Salam, S., and C.
Pignataro, "YANG Data Model for Generic Operations,
Administration, and Maintenance (OAM)", draft-tissa-
netmod-oam-01 (work in progress), June 2014.
[I-D.tissa-nvo3-yang-oam]
Senevirathne, T., "YANG Data Model for NVO3 Operations,
Administration, and Maintenance(OAM)", ID draft-tissa-
nvo3-yang-oam-00, June 2014.
[IEEE802.1Q]
"Media Access Control (MAC) Bridges and Virtual Bridged
Local Area Networks", IEEE Std 802.1Q-2011, August 2011.
[LIME-PS] Taylor, T., "Problem Statement for Layer and Technology
Independent OAM in a Multi-Layer Environment", ID draft-
edprop-opsawg-multi-layer-oam-ps, September 2014.
[LIME-UC] King, D., "Use Cases and Requirements for Layer
Independent OAM Management in multi-layer environments",
ID draft-king-opsawg-lime-multi-layer-oam-use-case,
September 2014.
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[MEF-30] "Service OAM Fault Management Implementation Agreement",
MEF 30, January 2011.
[MEF-31] "Service OAM Fault Management Definition of Managed
Objects", MEF 31, January 2011.
[MEF-35] "Service OAM Performance Monitoring Implementation
Agreement", MEF 35, January 2012.
[MEF-36] "Service OAM SNMP MIB for Performance Monitoring", MEF 36,
January 2012.
[MEF-38] "Service OAM Fault Management YANG Modules", MEF 38, April
2012.
[MEF-39] "Service OAM Performance Monitoring YANG Module", MEF 39,
April 2012.
[MEF-7.1] "EMS-NMS Information Model -Phase 2", Metro Ethernet Forum
MEF 7.1, 2009.
[Q.840.1] "Requirements and Analysis for NMS-EMS Management
Interface of Ethernet over Transport and Metro Ethernet
Network", Draft Recommendation ITU-T Q.840.1, 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC6291] Andersson, L., "Guidelines for the use of the "OAM"
Acronym in the IETF", RFC 6291, June 2011.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011.
[RFC7331] Nadeau, T., Ali, Z., and N. Akiya, "Bidirectional
Forwarding Detection (BFD) Management Information Base",
RFC 7331, August 2014.
[Y.1731] "OAM functions and mechanisms for Ethernet based
networks", ITU-T Recommendation G.8013/Y.1731, 2013.
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Authors' Addresses
Yuji Tochio
Fujitsu
Email: tochio@jp.fujitsu.com
Huub van Helvoort
Hai Gaoming BV
Email: huubatwork@gmail.com
Liang (Frank) Xia
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: Frank.xialiang@huawei.com
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