| Rfc | 6639 |
|---|
| Title | Multiprotocol Label Switching Transport Profile (MPLS-TP) MIB-Based
Management Overview |
|---|
| Author | D. King, Ed., M. Venkatesan, Ed. |
|---|
| Date | June 2012 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | INFORMATIONAL |
|---|
|
Internet Engineering Task Force (IETF) D. King, Ed.
Request for Comments: 6639 Old Dog Consulting
Category: Informational M. Venkatesan, Ed.
ISSN: 2070-1721 Aricent
June 2012
Multiprotocol Label Switching Transport Profile (MPLS-TP)
MIB-Based Management Overview
Abstract
A range of Management Information Base (MIB) modules has been
developed to help model and manage the various aspects of
Multiprotocol Label Switching (MPLS) networks. These MIB modules are
defined in separate documents that focus on the specific areas of
responsibility of the modules that they describe.
The MPLS Transport Profile (MPLS-TP) is a profile of MPLS
functionality specific to the construction of packet-switched
transport networks.
This document describes the MIB-based architecture for MPLS-TP,
indicates the interrelationships between different existing MIB
modules that can be leveraged for MPLS-TP network management, and
identifies areas where additional MIB modules are required.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6639.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................4
1.1. MPLS-TP Management Function ................................5
2. Terminology .....................................................5
3. The SNMP Management Framework ...................................5
4. Overview of Existing Work .......................................6
4.1. MPLS Management Overview and Requirements ..................6
4.2. An Introduction to the MPLS and Pseudowire MIB Modules .....6
4.2.1. Structure of the MPLS MIB OID Tree ..................6
4.2.2. Textual Convention Modules ..........................8
4.2.3. Label Switched Path (LSP) Modules ...................8
4.2.4. Label Edge Router (LER) Modules .....................8
4.2.5. Label Switching Router (LSR) Modules ................9
4.2.6. Pseudowire Modules ..................................9
4.2.7. Routing and Traffic Engineering ....................10
4.2.8. Resiliency .........................................11
4.2.9. Fault Management and Performance Management ........11
4.2.10. MIB Module Interdependencies ......................13
4.2.11. Dependencies on External MIB Modules ..............15
5. Applicability of MPLS MIB Modules to MPLS-TP ...................16
5.1. MPLS-TP Tunnel ............................................17
5.1.1. Gap Analysis .......................................17
5.1.2. Recommendations ....................................17
5.2. MPLS-TP Pseudowire ........................................17
5.2.1. Gap Analysis .......................................17
5.2.2. Recommendations ....................................18
5.3. MPLS-TP Sections ..........................................18
5.3.1. Gap Analysis .......................................18
5.3.2. Recommendations ....................................18
5.4. MPLS-TP OAM ...............................................18
5.4.1. Gap Analysis .......................................18
5.4.2. Recommendations ....................................19
5.5. MPLS-TP Protection Switching and Recovery .................19
5.5.1. Gap Analysis .......................................19
5.5.2. Recommendations ....................................19
5.6. MPLS-TP Interfaces ........................................19
5.6.1. Gap Analysis .......................................19
5.6.2. Recommendations ....................................19
6. An Introduction to the MPLS-TP MIB Modules .....................20
6.1. MPLS-TP MIB Modules .......................................20
6.1.1. New MIB Modules for MPLS-TP ........................20
6.1.2. Textual Conventions for MPLS-TP ....................20
6.1.3. Identifiers for MPLS-TP ............................21
6.1.4. LSR MIB Extensions for MPLS-TP .....................21
6.1.5. Tunnel Extensions for MPLS-TP ......................21
6.2. PWE3 MIB Modules for MPLS-TP ..............................21
6.2.1. New MIB Modules for MPLS-TP Pseudowires ............21
6.2.2. Pseudowire Textual Conventions for MPLS-TP .........21
6.2.3. Pseudowire Extensions for MPLS-TP ..................22
6.2.4. Pseudowire MPLS Extensions for MPLS-TP .............22
6.3. OAM MIB Modules for MPLS-TP ...............................22
6.3.1. New MIB Modules for OAM for MPLS-TP ................22
6.3.2. BFD MIB Module .....................................22
6.3.3. OAM MIB Module .....................................23
6.4. Protection Switching and Recovery MIB Modules for MPLS-TP .23
6.4.1. New MIB Modules for MPLS Protection
Switching and Recovery .............................23
6.4.2. Linear Protection Switching MIB Module .............23
6.4.3. Ring Protection Switching MIB Module ...............23
6.4.4. Mesh Protection Switching MIB Module ...............23
7. Management Options .............................................23
8. Security Considerations ........................................24
9. IANA Considerations ............................................24
10. Acknowledgements ..............................................24
11. Contributors' Addresses .......................................25
12. References ....................................................26
12.1. Normative References .....................................26
12.2. Informative References ...................................27
1. Introduction
The MPLS Transport Profile (MPLS-TP) is a packet transport technology
based on a profile of the MPLS functionality specific to the
construction of packet-switched transport networks. MPLS is
described in [RFC3031], and requirements for MPLS-TP are specified in
[RFC5654].
A range of Management Information Base (MIB) modules has been
developed to help model and manage the various aspects of
Multiprotocol Label Switching (MPLS) networks. These MIB modules are
defined in separate documents that focus on the specific areas of
responsibility for the modules that they describe.
An MPLS-TP network can be operated via static provisioning of
transport paths, Label Switched Paths (LSPs) and pseudowires (PWs),
or the elective use of a Generalized MPLS (GMPLS) control plane to
support dynamic provisioning of transport paths, LSPs, and PWs.
This document describes the MIB-based management architecture for
MPLS, as extended for MPLS-TP. The document also indicates the
interrelationships between existing MIB modules that should be
leveraged for MPLS-TP network management and identifies areas where
additional MIB modules are required.
Note that [RFC5951] does not specify a preferred management interface
protocol to be used as the standard protocol for managing MPLS-TP
networks.
1.1. MPLS-TP Management Function
The management of the MPLS-TP networks is separable from that of its
client networks so that the same means of management can be used
regardless of the client. The management function of MPLS-TP
includes fault management, configuration management, performance
monitoring, and security management.
The purpose of the management function is to provide control and
monitoring of the MPLS transport profile protocol mechanisms and
procedures. The requirements for the network management
functionality are found in [RFC5951]. A description of the network
and element management architectures that can be applied to the
management of MPLS-based transport networks is found in [RFC5950].
2. Terminology
This document also uses terminology from the MPLS architecture
document [RFC3031], Pseudowire Emulation Edge-to-Edge (PWE3)
architecture [RFC3985], and the following MPLS-related MIB modules:
the MPLS-TC-STD-MIB [RFC3811], MPLS-LSR-STD-MIB [RFC3813],
MPLS-TE-STD-MIB [RFC3812], MPLS-LDP-STD-MIB [RFC3815],
MPLS-FTN-STD-MIB [RFC3814], and TE-LINK-STD-MIB [RFC4220].
3. The SNMP Management Framework
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI).
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to Section 7 of
[RFC3410].
This document discusses MIB modules that are compliant to the SMIv2,
which is described in [RFC2578], [RFC2579], and [RFC2580].
4. Overview of Existing Work
This section describes the existing tools and techniques for managing
and modeling MPLS networks, devices, and protocols. It is intended
to provide a description of the tool kit that is already available.
Section 5 of this document outlines the applicability of existing
MPLS MIB modules to MPLS-TP, describes the optional use of GMPLS MIB
modules in MPLS-TP networks, and examines the additional MIB modules
and objects that would be required for managing an MPLS-TP network.
4.1. MPLS Management Overview and Requirements
[RFC4378] outlines how data-plane protocols can assist in providing
the Operations, Administration, and Maintenance (OAM) requirements
outlined in [RFC4377] and how it is applied to the management
functions of fault, configuration, accounting, performance, and
security (commonly known as FCAPS) for MPLS networks.
[RFC4221] describes the management architecture for MPLS. In
particular, it describes how the managed objects defined in various
MPLS-related MIB modules model different aspects of MPLS, as well as
the interactions and dependencies between each of these MIB modules.
[RFC4377] describes the requirements for user- and data-plane OAM and
applications for MPLS.
[RFC5654] describes the requirements for the optional use of a
control plane to support dynamic provisioning of MPLS-TP transport
paths. The MPLS-TP LSP control plane is based on GMPLS and is
described in [RFC3945].
4.2. An Introduction to the MPLS and Pseudowire MIB Modules
4.2.1. Structure of the MPLS MIB OID Tree
The MPLS MIB Object Identifier (OID) tree has the following
structure. It is based on the tree originally set out in Section 4.1
of [RFC4221] and has been enhanced to include other relevant MIB
modules.
mib-2 -- RFC 2578 [RFC2578]
|
+-transmission
| |
| +- mplsStdMIB
| | |
| | +- mplsTCStdMIB -- MPLS-TC-STD-MIB [RFC3811]
| | |
| | +- mplsLsrStdMIB -- MPLS-LSR-STD-MIB [RFC3813]
| | |
| | +- mplsTeStdMIB -- MPLS-TE-STD-MIB [RFC3812]
| | |
| | +- mplsLdpStdMIB -- MPLS-LDP-STD-MIB [RFC3815]
| | |
| | +- mplsLdpGenericStdMIB
| | | -- MPLS-LDP-GENERIC-STD-MIB [RFC3815]
| | |
| | +- mplsFTNStdMIB -- MPLS-FTN-STD-MIB [RFC3814]
| | |
| | +- gmplsTCStdMIB -- GMPLS-TC-STD-MIB [RFC4801]
| | |
| | +- gmplsTeStdMIB -- GMPLS-TE-STD-MIB [RFC4802]
| | |
| | +- gmplsLsrStdMIB -- GMPLS-LSR-STD-MIB [RFC4803]
| | |
| | +- gmplsLabelStdMIB -- GMPLS-LABEL-STD-MIB [RFC4803]
| |
| +- teLinkStdMIB -- TE-LINK-STD-MIB [RFC4220]
| |
| +- pwStdMIB -- PW-STD-MIB [RFC5601]
|
+- ianaGmpls -- IANA-GMPLS-TC-MIB [RFC4802]
|
+- ianaPwe3MIB -- IANA-PWE3-MIB [RFC5601]
|
+- pwEnetStdMIB -- PW-ENET-STD-MIB [RFC5603]
|
+- pwMplsStdMIB -- PW-MPLS-STD-MIB [RFC5602]
|
+- pwTDMMIB -- PW-TDM-MIB [RFC5604]
|
+- pwTcStdMIB -- PW-TC-STD-MIB [RFC5542]
Note: The OIDs for MIB modules are assigned and managed by IANA.
They can be found in the referenced MIB documents.
4.2.2. Textual Convention Modules
The MPLS-TC-STD-MIB [RFC3811], GMPLS-TC-STD-MIB [RFC4801],
IANA-GMPLS-TC-MIB [RFC4802], and PW-TC-STD-MIB [RFC5542] contain the
Textual Conventions for MPLS and GMPLS networks. These Textual
Conventions should be imported by MIB modules that manage MPLS and
GMPLS networks. Section 4.2.11 highlights dependencies on additional
external MIB modules.
4.2.3. Label Switched Path (LSP) Modules
An LSP is a path over which a labeled packet travels across the
sequence of Label Switching Routers (LSRs) for a given Forward
Equivalence Class (FEC). When a packet, with or without a label,
arrives at an ingress Label Edge Router (LER) of an LSP, it is
encapsulated with the label corresponding to the FEC and sent across
the LSP. The labeled packet traverses the LSRs and arrives at the
egress LER of the LSP, where it gets forwarded, depending on the
packet type it came with. LSPs could be nested using label stacking,
such that an LSP could traverse another LSP. A more detailed
description of an LSP can be found in [RFC3031].
The MPLS-LSR-STD-MIB [RFC3813] describes the objects required to
define the LSP.
4.2.4. Label Edge Router (LER) Modules
Ingress and egress LSRs of an LSP are known as Label Edge Routers
(LERs). An ingress LER takes each incoming unlabeled or labeled
packet and encapsulates it with the corresponding label of the LSP it
represents, and then forwards it to the adjacent LSR of the LSP.
Each FEC is mapped to a label-forwarding entry, so that a packet
could be encapsulated with one or more label entries; this is
referred to as a label stack.
The packet traverses the LSP. Upon reaching the egress LER, further
action will be taken to handle the packet, depending on the type of
packet received. MPLS Architecture [RFC3031] details the
functionality of ingress and egress LERs.
The MPLS-FTN-STD-MIB [RFC3814] describes the managed objects for
mapping FEC to label bindings.
4.2.5. Label Switching Router (LSR) Modules
A router that performs MPLS forwarding is known as an LSR. An LSR
receives a labeled packet and performs forwarding action based on the
label received.
The LSR maintains a mapping of an incoming label and incoming
interface to one or more outgoing labels and outgoing interfaces in
its forwarding database. When a labeled packet is received, the LSR
examines the topmost label in the label stack and then does a 'swap',
'push', or 'pop' operation based on the contents.
The MPLS-LSR-STD-MIB [RFC3813] describes the managed objects for
modeling an MPLS [RFC3031] LSR. The MPLS-LSR-STD-MIB [RFC3813]
contains the managed objects to maintain mapping of in-segments to
out-segments.
4.2.6. Pseudowire Modules
The pseudowire (PW) MIB architecture provides a layered modular model
into which any supported emulated service such as Frame Relay, ATM,
Ethernet, Time-Division Multiplexing (TDM), and Synchronous Optical
Network/Synchronous Digital Hierarchy (SONET/SDH) can be connected to
any supported Packet Switched Network (PSN) type. This MIB
architecture is modeled based on PW3 architecture [RFC3985].
The emulated service layer, generic PW layer, and PSN Virtual Circuit
(VC) layer constitute the different layers of the model. A
combination of the MIB modules belonging to each layer provides the
glue for mapping the emulated service onto the native PSN service.
At least three MIB modules, each belonging to a different layer, are
required to define a PW emulated service.
- The service-specific module is dependent on the emulated signal
type and helps in modeling the emulated service layer.
The PW-ENET-STD-MIB [RFC5603] describes a model for managing Ethernet
pseudowire services for transmission over a PSN. This MIB module is
generic and common to all types of PSNs supported in the PWE3
Architecture [RFC3985], which describes the transport and
encapsulation of L1 and L2 services over supported PSN types.
In particular, the MIB module associates a port or specific VLANs on
top of a physical Ethernet port or a virtual Ethernet interface (for
the Virtual Private LAN Service (VPLS)) to a point-to-point PW. It
is complementary to the PW-STD-MIB [RFC5601], which manages the
generic PW parameters common to all services, including all supported
PSN types.
The PW-TDM-MIB [RFC5604] describes a model for managing TDM
pseudowires, i.e., TDM data encapsulated for transmission over a PSN.
The term "TDM" in this document is limited to the scope of
Plesiochronous Digital Hierarchy (PDH). It is currently specified to
carry any TDM signals in either Structure Agnostic Transport mode
(E1, T1, E3, and T3) or Structure Aware Transport mode (E1, T1, and
NxDS0) as defined in the PWE3 TDM Requirements document [RFC4197].
- The generic PW module configures general parameters of the PW that
are common to all types of emulated services and PSN types.
The PW-STD-MIB [RFC5601] defines a MIB module that can be used to
manage PW services for transmission over a PSN [RFC3931] [RFC4447].
This MIB module provides generic management of PWs that is common to
all types of PSN and PW services defined by the IETF PWE3 Working
Group.
- The PSN-specific module associates the PW with one or more
"tunnels" that carry the service over the PSN. There is a
different module for each type of PSN.
The PW-MPLS-STD-MIB [RFC5602] describes a model for managing
pseudowire services for transmission over different flavors of MPLS
tunnels. The generic PW MIB module [RFC5601] defines the parameters
global to the PW, regardless of the underlying PSN and emulated
service. This document is applicable for PWs that use the MPLS PSN
type in the PW-STD-MIB. Additionally, this document describes the
MIB objects that define pseudowire association to the MPLS PSN that
is not specific to the carried service.
Together, [RFC3811], [RFC3812], and [RFC3813] describe the modeling
of an MPLS tunnel and a tunnel's underlying cross-connects. This MIB
module supports MPLS Traffic Engineering (MPLS-TE) PSNs, non-TE MPLS
PSNs (an outer tunnel created by the Label Distribution Protocol
(LDP) or manually), and MPLS PW labels only (no outer tunnel).
4.2.7. Routing and Traffic Engineering
In MPLS traffic engineering, it's possible to specify explicit routes
or choose routes based on QoS metrics in setting up a path such that
some specific data can be routed around network hot spots. TE LSPs
can be set up through a management plane or a control plane.
The MPLS-TE-STD-MIB [RFC3812] describes managed objects for modeling
MPLS [RFC3031]-based traffic engineering. This MIB module should be
used in conjunction with the companion document [RFC3813] for MPLS-
based traffic engineering configuration and management.
4.2.8. Resiliency
The purpose of MPLS resiliency is to ensure minimal interruption to
traffic when a failure occurs within the system or network.
Various components of MPLS resiliency solutions are as follows:
1) Graceful restart in LDP and RSVP-TE modules
2) Make before break
3) Protection switching for LSPs
4) Fast reroute for LSPs
5) PW redundancy
The MIB modules below only support MIB-based management for MPLS
resiliency.
MPLS Fast Reroute (FRR) is a restoration network resiliency mechanism
used in MPLS TE to redirect traffic onto the backup LSPs in tens of
milliseconds in case of link or node failure across the LSP.
The MPLS-FRR-GENERAL-STD-MIB [RFC6445] contains objects that apply to
any MPLS LSR implementing MPLS TE fast-reroute functionality.
The MPLS-FRR-ONE2ONE-STD-MIB [RFC6445] contains objects that apply to
the one-to-one backup method.
The MPLS-FRR-FACILITY-STD-MIB [RFC6445] contains objects that apply
to the facility backup method.
Protection switching mechanisms have been designed to provide network
resiliency for MPLS networks. Different types of protection
switching mechanisms, such as 1:1, 1:N, and 1+1, have been designed.
4.2.9. Fault Management and Performance Management
MPLS manages LSP and pseudowire faults through the use of LSP ping
[RFC4379], Virtual Circuit Connectivity Verification (VCCV)
[RFC5085], Bidirectional Forwarding Detection (BFD) for LSPs
[RFC5884], and BFD for VCCV [RFC5885] tools.
MPLS currently focuses on in and/or out packet counters, errored
packets, and discontinuity time.
Some of the MPLS and pseudowire performance tables used for
performance management are given below.
The mplsTunnelPerfTable [RFC3812] provides several counters (e.g.,
packets forwarded, packets dropped because of errors) to measure the
performance of the MPLS tunnels.
The mplsInterfacePerfTable [RFC3813] provides performance information
(incoming and outgoing labels in use, and lookup failures) on a
per-interface basis.
The mplsInSegmentPerfTable [RFC3813] contains statistical information
(total packets received by the in-segment, total errored packets
received, total packets discarded, discontinuity time) for incoming
MPLS segments to an LSR.
The mplsOutSegmentPerfTable [RFC3813] contains statistical
information (total packets received, total errored packets received,
total packets discarded, discontinuity time) for outgoing MPLS
segments from an LSR.
The mplsFTNPerfTable [RFC3814] contains performance information for
the specified interface and an FTN entry mapped to this interface.
The mplsLdpEntityStatsTable [RFC3815] and mplsLdpSessionStatsTable
[RFC3815] contain statistical information (session attempts, errored
packets, notifications) about an LDP entity.
The pwPerfCurrentTable [RFC5601], pwPerfIntervalTable [RFC5601], and
pwPerf1DayIntervalTable [RFC5601] provide pseudowire performance
information (in and/or out packets) based on time (current interval,
preconfigured specific interval, 1-day interval).
The pwEnetStatsTable [RFC5603] contains statistical counters specific
for Ethernet PW.
The pwTDMPerfCurrentTable [RFC5604], pwTDMPerfIntervalTable
[RFC5604], and pwTDMPerf1DayIntervalTable [RFC5604] contain
statistical information accumulated per 15-minute, 24-hour, and 1-day
periods, respectively.
The gmplsTunnelErrorTable [RFC4802] and gmplsTunnelReversePerfTable
[RFC4802] provide information about performance, errored packets, and
in/out packet counters.
4.2.10. MIB Module Interdependencies
This section provides an overview of the relationship between the
MPLS MIB modules for managing MPLS networks. More details of these
relationships are given below.
[RFC4221] mainly focuses on MPLS MIB module interdependencies. This
section also highlights GMPLS and PW MIB module interdependencies.
The relationship "A --> B" means that A depends on B and that MIB
module A uses an object, object identifier, or Textual Convention
defined in MIB module B, or that MIB module A contains a pointer
(index or RowPointer) to an object in MIB module B.
+-------> MPLS-TC-STD-MIB <-----------------------------------------+
^ ^ ^
| | |
| MPLS-LSR-STD-MIB <--------------------------------+ |
| ^ |
| | |
+<----------------------- MPLS-LDP-STD-MIB ---------------->+ |
^ ^ ^ |
| | | |
+<-- MPLS-LDP-GENERIC-STD-MIB ------>+ | |
^ | |
| | |
+<------ MPLS-FTN-STD-MIB --------------------------------->+ |
^ | ^ |
| V | |
+<------------- MPLS-TE-STD-MIB -->+----------------------->+ |
^ GMPLS-TC-STD-MIB ------------>+
| ^ ^
| | |
+---+ +<-- GMPLS-LABEL-STD-MIB -->+
^ ^ ^ ^ ^
| | | | |
+----> PW-TC-STD-MIB | GMPLS-LSR-STD-MIB --------------->+
^ | ^ ^ ^
| | | | |
| IANA-PWE3-MIB | | | IANA-GMPLS-TC-MIB |
| ^ | | | ^ |
| | | | | | |
| | +<--- GMPLS-TE-STD-MIB ------------->+
| | ^ ^
+<--- PW-STD-MIB <------+ | |
^ ^ | |
| | | |
+<--- PW-ENET-STD-MIB ->+ | |
^ ^ | |
| | | |
| | | |
+<---------------- PW-MPLS-STD-MIB--------------------------------->+
Thus,
- All the MPLS MIB modules depend on the MPLS-TC-STD-MIB.
- All the GMPLS MIB modules depend on the GMPLS-TC-STD-MIB.
- All the PW MIB modules depend on the PW-TC-STD-MIB.
- The MPLS-LDP-STD-MIB, MPLS-TE-STD-MIB, MPLS-FTN-STD-MIB,
GMPLS-LSR-STD-MIB, and PW-MPLS-STD-MIB contain references to
objects in the MPLS-LSR-STD-MIB.
- The MPLS-LDP-GENERIC-STD-MIB contains references to objects in the
MPLS-LDP-STD-MIB.
- The MPLS-FTN-STD-MIB, PW-MPLS-STD-MIB, and GMPLS-TE-STD-MIB
contain references to objects in the MPLS-TE-STD-MIB.
- The PW-MPLS-STD-MIB and PW-ENET-STD-MIB contain references to
objects in the PW-STD-MIB.
- The PW-STD-MIB contains references to objects in the
IANA-PWE3-MIB.
- The GMPLS-TE-STD-MIB contains references to objects in the
IANA-GMPLS-TC-MIB.
- The GMPLS-LSR-STD-MIB contains references to objects in the
GMPLS-LABEL-STD-MIB.
Note that there is a Textual Convention (MplsIndexType) defined in
the MPLS-LSR-STD-MIB that is imported by the MPLS-LDP-STD-MIB.
4.2.11. Dependencies on External MIB Modules
With the exception of the MPLS-TC-STD-MIB, all the MPLS MIB modules
have dependencies on the Interfaces MIB (also called the Interfaces
Group MIB or the IF-MIB) [RFC2863]. The MPLS-FTN-STD-MIB references
IP-capable interfaces on which received traffic is to be classified
using indexes in the Interfaces Table (ifTable) of the IF-MIB
[RFC2863]. The other MPLS MIB modules reference MPLS-capable
interfaces in the ifTable.
The IF-MIB [RFC2863] defines generic managed objects for managing
interfaces. The MPLS MIB modules contain media-specific extensions
to the Interfaces Group for managing MPLS interfaces.
The MPLS MIB modules assume the interpretation of the Interfaces
Group to be in accordance with [RFC2863], which states that the
ifTable contains information on the managed resource's interfaces and
that each sub-layer below the internetwork layer of a network
interface is considered an interface. Thus, the MPLS interface is
represented as an entry in the ifTable.
The interrelation of entries in the ifTable is defined by the
Interface Stack Group defined in [RFC2863].
The MPLS MIB modules have dependencies on the TE-LINK-STD-MIB for
maintaining traffic engineering information.
The MPLS MIB modules depend on the Constrained Shortest Path First
(CSPF) component to obtain the path required for an MPLS tunnel to
reach the end point of the tunnel, and on the BFD component to verify
data-plane failures of LSPs and PWs.
Finally, all of the MIB modules import standard Textual Conventions
such as integers, strings, timestamps, etc., from the MIB modules in
which they are defined.
5. Applicability of MPLS MIB Modules to MPLS-TP
This section highlights gaps in existing MPLS MIB modules in order to
determine extensions or additional MIB modules that are required to
support MPLS-TP in MPLS networks.
[RFC5951] specifies the requirements for the management of equipment
used in networks supporting MPLS-TP. It also details the essential
network management capabilities for operating networks consisting of
MPLS-TP equipment.
[RFC5950] provides the network management framework for MPLS-TP. The
document explains how network elements and networks that support
MPLS-TP can be managed using solutions that satisfy the requirements
defined in [RFC5951]. The relationship between MPLS-TP management
and OAM is described in the MPLS-TP framework document [RFC5950].
The MPLS MIB documents MPLS-TE-STD-MIB [RFC3812], PW-STD-MIB
[RFC5601], and MPLS-LSR-STD-MIB [RFC3813], and their associated MIB
modules, are reused for MPLS-based transport network management.
Fault management and performance management form key parts of the OAM
function. MPLS-TP OAM is described in [RFC6371].
5.1. MPLS-TP Tunnel
5.1.1. Gap Analysis
An MPLS-TP tunnel can be operated over IP and/or ITU-T Carrier Code
(ICC) environments. The points below capture the gaps in existing
MPLS MIB modules for managing MPLS-TP networks.
- IP-based environment
i. The MPLS-TE-STD-MIB [RFC3812] does not support the tunnel
Ingress/Egress identifier based on Global_ID and Node_ID
[RFC6370].
ii. The MPLS-TE-STD-MIB [RFC3812] does not support
co-routed/associated bidirectional tunnel configurations.
- ICC-based environment
i. The MPLS-TE-STD-MIB [RFC3812] does not support the tunnel LSR
identifier based on ICC.
5.1.2. Recommendations
- New MIB definitions may be created for Global_Node_ID and/or ICC
configurations.
- The MPLS-LSR-STD-MIB [RFC3813] module may be enhanced to identify
the next hop based on a Media Access Control (MAC) address for
environments that do not use IP. The mplsOutSegmentTable may be
extended to hold the MAC address.
- The MPLS-TE-STD-MIB [RFC3812] and MPLS-LSR-STD-MIB may be enhanced
to provide static and signaling MIB module extensions for
co-routed/associated bidirectional LSPs.
5.2. MPLS-TP Pseudowire
5.2.1. Gap Analysis
MPLS-TP pseudowire can be operated over IP and/or ICC environments.
The points below capture the gaps in existing PW MIB modules for
managing MPLS-TP networks.
[RFC6370] specifies an initial set of identifiers to be used in
MPLS-TP. These identifiers were chosen to be compatible with
existing MPLS, GMPLS, and PW definitions.
- IP-based environment
i. The PW-STD-MIB [RFC5601] does not support the PW end point
identifier based on Global_ID and Node_ID.
ii. The PW-MPLS-STD-MIB [RFC5602] does not support operation over
co-routed/associated bidirectional tunnels.
- ICC-based environment
i. The PW-STD-MIB [RFC5601] does not support the PW end point
identifier based on ICC.
5.2.2. Recommendations
- The PW-MPLS-STD-MIB [RFC5602] can be enhanced to operate over
co-routed/associated bidirectional tunnels.
5.3. MPLS-TP Sections
5.3.1. Gap Analysis
The existing MPLS MIB modules do not support MPLS-TP sections.
5.3.2. Recommendations
Link-specific and/or path/segment-specific sections can be supported
by enhancing the IF-MIB [RFC2863], MPLS-TE-STD-MIB [RFC3812], and
PW-STD-MIB [RFC5601] MIB modules.
5.4. MPLS-TP OAM
5.4.1. Gap Analysis
MPLS manages LSP and pseudowire faults through LSP ping [RFC4379],
VCCV [RFC5085], BFD for LSPs [RFC5884], and BFD for VCCV [RFC5885]
tools.
The MPLS MIB modules do not support the following MPLS-TP OAM
functions:
o Continuity Check and Connectivity Verification
o Remote Defect Indication
o Alarm Reporting
o Lock Reporting
o Lock Instruct
o Client Failure Indication
o Packet Loss Measurement
o Packet Delay Measurement
5.4.2. Recommendations
New MIB module for BFD can be created to address all the gaps
mentioned in Section 5.4.1.
5.5. MPLS-TP Protection Switching and Recovery
5.5.1. Gap Analysis
An important aspect that MPLS-TP technology provides is protection
switching. In general, the mechanism of protection switching can be
described as the substitution of a protection or standby facility for
a working or primary facility.
The MPLS MIB modules do not provide support for protection switching
and recovery in the following three topologies: linear, ring, and
mesh.
5.5.2. Recommendations
New MIB modules can be created to address all the gaps mentioned in
Section 5.5.1.
5.6. MPLS-TP Interfaces
5.6.1. Gap Analysis
As per [RFC6370], an LSR requires identification of the node itself
and of its interfaces. An interface is the attachment point to a
server layer MPLS-TP section or MPLS-TP tunnel.
The MPLS MIB modules do not provide support for configuring the
interfaces within the context of an operator.
5.6.2. Recommendations
New MIB definitions can be created to address the gaps mentioned in
Section 5.6.1.
6. An Introduction to the MPLS-TP MIB Modules
This section highlights new MIB modules that have been identified as
being required for MPLS-TP. This section also provides an overview
of the purpose of each MIB module within the MIB documents, what it
can be used for, and how it relates to the other MIB modules.
Note that each new MIB module (apart from Textual Conventions
modules) will contain one or more Compliance Statements to indicate
which objects must be supported in what manner to claim a specific
level of compliance. Additional text, either in the documents that
define the MIB modules or in separate Applicability Statements, will
define which Compliance Statements need to be conformed to in order
to provide specific MPLS-TP functionality. This document does not
set any requirements in that respect, although some recommendations
are included in the sections that follow.
6.1. MPLS-TP MIB Modules
6.1.1. New MIB Modules for MPLS-TP
Four new MIB modules are identified as follows:
- Textual Conventions for MPLS-TP
- Identifiers for MPLS-TP
- LSR MIB Extensions for MPLS-TP
- Tunnel Extensions for MPLS-TP
Note that the MIB modules mentioned here are applicable for MPLS
operations as well.
6.1.2. Textual Conventions for MPLS-TP
A new MIB module needs to be written that will define Textual
Conventions [RFC2579] for MPLS-TP-related MIB modules. These
conventions allow multiple MIB modules to use the same syntax and
format to provide a concept that is shared between the MIB modules.
For example, a Maintenance Entity Group End Point (MEP) identifier is
used to identify a maintenance entity group end point within MPLS-TP
networks. The Textual Convention representing the MEP identifier
should be defined in a new Textual Convention MIB module.
All new extensions related to MPLS-TP are defined in the MIB module
and will be referenced by other MIB modules to support MPLS-TP.
6.1.3. Identifiers for MPLS-TP
New identifiers describe managed objects that are used to model
common MPLS-TP identifiers [RFC6370].
6.1.4. LSR MIB Extensions for MPLS-TP
The MPLS-LSR-STD-MIB describes managed objects for modeling an MPLS
LSR. This puts it at the heart of the management architecture for
MPLS.
In the case of MPLS-TP, the MPLS-LSR-STD-MIB is extended to support
MPLS-TP LSPs, which are co-routed or associated bidirectionally.
This extended MIB is also applicable for modeling MPLS-TP tunnels.
6.1.5. Tunnel Extensions for MPLS-TP
The MPLS-TE-STD-MIB describes managed objects that are used to model
and manage MPLS-TE tunnels.
MPLS-TP tunnels are very similar to MPLS-TE tunnels but are co-routed
or associated bidirectionally.
The MPLS-TE-STD-MIB must be extended to support the MPLS-TP-specific
attributes for the tunnel.
6.2. PWE3 MIB Modules for MPLS-TP
This section provides an overview of pseudowire-extension MIB modules
used to meet MPLS-based transport network requirements.
6.2.1. New MIB Modules for MPLS-TP Pseudowires
Three new MIB modules are identified as follows:
- Pseudowire Textual Conventions for MPLS-TP
- Pseudowire Extensions for MPLS-TP
- Pseudowire MPLS Extensions for MPLS-TP
6.2.2. Pseudowire Textual Conventions for MPLS-TP
The PW-TC-STD-MIB defines Textual Conventions used for PW technology
and for PWE3 MIB modules. A new Textual Convention MIB module is
required to define textual definitions for MPLS-TP-specific
pseudowire attributes.
6.2.3. Pseudowire Extensions for MPLS-TP
The PW-STD-MIB describes managed objects for the modeling of
pseudowire edge-to-edge services carried over a general PSN. This
MIB module is extended to support MPLS-TP-specific attributes related
to pseudowires.
6.2.4. Pseudowire MPLS Extensions for MPLS-TP
The PW-MPLS-STD-MIB defines the managed objects for pseudowire
operations over MPLS LSRs. This MIB module supports
- manually and dynamically signaled PWs
- point-to-point connections
- the use of any emulated service
- outer tunnels provisioned using MPLS-TE
- PWs with no outer tunnel
An extended MIB module would define additional objects, extending the
PW-MPLS-STD-MIB by continuing to support configurations that operate
with or without an outer tunnel.
6.3. OAM MIB Modules for MPLS-TP
This section provides an overview of Operations, Administration, and
Maintenance (OAM) MIB modules for MPLS LSPs and pseudowires.
6.3.1. New MIB Modules for OAM for MPLS-TP
Two new MIB modules are identified as follows:
- BFD MIB module
- OAM MIB module
6.3.2. BFD MIB Module
The BFD-STD-MIB defines managed objects for performing BFD operations
in IP networks. This MIB module is modeled to support the BFD
protocol [RFC5880].
A new MIB module needs to be written that will be an extension to
BFD-STD-MIB managed objects to support BFD operations on MPLS LSPs
and PWs.
6.3.3. OAM MIB Module
A new MIB module needs to be written that will define managed objects
for OAM maintenance identifiers, i.e., Maintenance Entity Group (MEG)
identifiers, the MEP, and the Maintenance Entity Group Intermediate
Point (MIP). Maintenance points are uniquely associated with a MEG.
Within the context of a MEG, MEPs and MIPs must be uniquely
identified.
6.4. Protection Switching and Recovery MIB Modules for MPLS-TP
This section provides an overview of protection switching and
recovery MIB modules for MPLS LSPs and pseudowires.
6.4.1. New MIB Modules for MPLS Protection Switching and Recovery
Three new MIB modules are identified as follows:
- Linear Protection Switching MIB module
- Ring Protection Switching MIB module
- Mesh Protection Switching MIB module
6.4.2. Linear Protection Switching MIB Module
A new MIB module needs to be written that will define managed objects
for linear protection switching of MPLS LSPs and pseudowires.
6.4.3. Ring Protection Switching MIB Module
A new MIB module needs to be written that will define managed objects
for ring protection switching of MPLS LSPs and pseudowires.
6.4.4. Mesh Protection Switching MIB Module
A new MIB module needs to be written that will define managed objects
for mesh protection switching of MPLS LSPs and pseudowires.
7. Management Options
This document applies only to scenarios where MIB modules are used to
manage the MPLS-TP network. It is not the intention of this document
to provide instructions or advice to implementers of management
systems, management agents, or managed entities. It is, however,
useful to make some observations about how the MIB modules described
above might be used to manage MPLS systems, if SNMP is used in the
management interface.
For MPLS-specific management options, refer to [RFC4221] Section 12
("Management Options").
8. Security Considerations
This document describes the interrelationships amongst the different
MIB modules relevant to MPLS-TP management and as such does not have
any security implications in and of itself.
Each IETF MIB document that specifies MIB objects for MPLS-TP must
provide a proper Security Considerations section that explains the
security aspects of those objects.
The attention of readers is particularly drawn to the security
implications of making MIB objects available for create or write
access through an access protocol such as SNMP. SNMPv1 by itself is
an insecure environment. Even if the network itself is made secure
(for example, by using IPsec), there is no control over who on the
secure network is allowed to access the objects in the MIB module.
It is recommended that the implementers consider the security
features as provided by the SNMPv3 framework. Specifically, the use
of the User-based Security Model STD 62, RFC 3414 [RFC3414], and the
View-based Access Control Model STD 62, RFC 3415 [RFC3415], is
recommended.
It is then a customer/user responsibility to ensure that the SNMP
entity giving access to an instance of each MIB module is properly
configured to give access to only those objects, and to those
principals (users) that have legitimate rights to access them.
9. IANA Considerations
This document has identified areas where additional MIB modules are
necessary for MPLS-TP. The new MIB modules recommended by this
document will require OID assignments from IANA. However, this
document makes no specific request for IANA action.
10. Acknowledgements
The authors would like to thank Eric Gray, Thomas Nadeau, Benjamin
Niven-Jenkins, Saravanan Narasimhan, Joel Halpern, David Harrington,
and Stephen Farrell for their valuable comments.
This document also benefited from review by participants in ITU-T
Study Group 15.
11. Contributors' Addresses
Adrian Farrel
Old Dog Consulting
UK
EMail: adrian@olddog.co.uk
Scott Mansfield
Ericsson
300 Holger Way
San Jose, CA 95134
US
Phone: +1 724 931 9316
EMail: scott.mansfield@ericsson.com
Jeong-dong Ryoo
ETRI
161 Gajeong, Yuseong
Daejeon, 305-700
South Korea
Phone: +82 42 860 5384
EMail: ryoo@etri.re.kr
A S Kiran Koushik
Cisco Systems Inc.
EMail: kkoushik@cisco.com
A. Karmakar
Cisco Systems Inc.
EMail: akarmaka@cisco.com
Sam Aldrin
Huawei Technologies Co.
2330 Central Expressway
Santa Clara, CA 95051
USA
EMail: aldrin.ietf@gmail.com
12. References
12.1. Normative References
[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
MIB", RFC 2863, June 2000.
[RFC3811] Nadeau, T., Ed., and J. Cucchiara, Ed., "Definitions of
Textual Conventions (TCs) for Multiprotocol Label
Switching (MPLS) Management", RFC 3811, June 2004.
[RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Traffic Engineering
(TE) Management Information Base (MIB)", RFC 3812,
June 2004.
[RFC3813] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Label Switching
Router (LSR) Management Information Base (MIB)",
RFC 3813, June 2004.
[RFC3814] Nadeau, T., Srinivasan, C., and A. Viswanathan,
"Multiprotocol Label Switching (MPLS) Forwarding
Equivalence Class To Next Hop Label Forwarding Entry
(FEC-To-NHLFE) Management Information Base (MIB)",
RFC 3814, June 2004.
[RFC3815] Cucchiara, J., Sjostrand, H., and J. Luciani,
"Definitions of Managed Objects for the Multiprotocol
Label Switching (MPLS), Label Distribution Protocol
(LDP)", RFC 3815, June 2004.
[RFC4220] Dubuc, M., Nadeau, T., and J. Lang, "Traffic Engineering
Link Management Information Base", RFC 4220,
November 2005.
[RFC4221] Nadeau, T., Srinivasan, C., and A. Farrel, "Multiprotocol
Label Switching (MPLS) Management Overview", RFC 4221,
November 2005.
[RFC4801] Nadeau, T., Ed., and A. Farrel, Ed., "Definitions of
Textual Conventions for Generalized Multiprotocol Label
Switching (GMPLS) Management", RFC 4801, February 2007.
[RFC4802] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized
Multiprotocol Label Switching (GMPLS) Traffic Engineering
Management Information Base", RFC 4802, February 2007.
[RFC4803] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized
Multiprotocol Label Switching (GMPLS) Label Switching
Router (LSR) Management Information Base", RFC 4803,
February 2007.
[RFC5542] Nadeau, T., Ed., Zelig, D., Ed., and O. Nicklass, Ed.,
"Definitions of Textual Conventions for Pseudowire (PW)
Management", RFC 5542, May 2009.
[RFC5601] Nadeau, T., Ed., and D. Zelig, Ed., "Pseudowire (PW)
Management Information Base (MIB)", RFC 5601, July 2009.
[RFC5602] Zelig, D., Ed., and T. Nadeau, Ed., "Pseudowire (PW) over
MPLS PSN Management Information Base (MIB)", RFC 5602,
July 2009.
[RFC5603] Zelig, D., Ed., and T. Nadeau, Ed., "Ethernet Pseudowire
(PW) Management Information Base (MIB)", RFC 5603,
July 2009.
[RFC5604] Nicklass, O., "Managed Objects for Time Division
Multiplexing (TDM) over Packet Switched Networks (PSNs)",
RFC 5604, July 2009.
12.2. Informative References
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Textual Conventions for SMIv2",
STD 58, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Conformance Statements for SMIv2",
STD 58, RFC 2580, April 1999.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.
[RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model
(USM) for version 3 of the Simple Network Management
Protocol (SNMPv3)", STD 62, RFC 3414, December 2002.
[RFC3415] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based
Access Control Model (VACM) for the Simple Network
Management Protocol (SNMP)", STD 62, RFC 3415,
December 2002.
[RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed.,
"Layer Two Tunneling Protocol - Version 3 (L2TPv3)",
RFC 3931, March 2005.
[RFC3945] Mannie, E., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, October 2004.
[RFC3985] Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC4197] Riegel, M., Ed., "Requirements for Edge-to-Edge Emulation
of Time Division Multiplexed (TDM) Circuits over Packet
Switching Networks", RFC 4197, October 2005.
[RFC4377] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S.
Matsushima, "Operations and Management (OAM) Requirements
for Multi-Protocol Label Switched (MPLS) Networks",
RFC 4377, February 2006.
[RFC4378] Allan, D., Ed., and T. Nadeau, Ed., "A Framework for
Multi-Protocol Label Switching (MPLS) Operations and
Management (OAM)", RFC 4378, February 2006.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006.
[RFC4447] Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and
G. Heron, "Pseudowire Setup and Maintenance Using the
Label Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC5085] Nadeau, T., Ed., and C. Pignataro, Ed., "Pseudowire
Virtual Circuit Connectivity Verification (VCCV): A
Control Channel for Pseudowires", RFC 5085,
December 2007.
[RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M.,
Ed., Sprecher, N., and S. Ueno, "Requirements of an MPLS
Transport Profile", RFC 5654, September 2009.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, June 2010.
[RFC5885] Nadeau, T., Ed., and C. Pignataro, Ed., "Bidirectional
Forwarding Detection (BFD) for the Pseudowire Virtual
Circuit Connectivity Verification (VCCV)", RFC 5885,
June 2010.
[RFC5950] Mansfield, S., Ed., Gray, E., Ed., and K. Lam, Ed.,
"Network Management Framework for MPLS-based Transport
Networks", RFC 5950, September 2010.
[RFC5951] Lam, K., Mansfield, S., and E. Gray, "Network Management
Requirements for MPLS-based Transport Networks",
RFC 5951, September 2010.
[RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.
[RFC6371] Busi, I., Ed., and D. Allan, Ed., "Operations,
Administration, and Maintenance Framework for MPLS-Based
Transport Networks", RFC 6371, September 2011.
[RFC6445] Nadeau, T., Ed., Koushik, A., Ed., and R. Cetin, Ed.,
"Multiprotocol Label Switching (MPLS) Traffic Engineering
Management Information Base for Fast Reroute", RFC 6445,
November 2011.
Authors' Addresses
Daniel King (editor)
Old Dog Consulting
UK
EMail: daniel@olddog.co.uk
Venkatesan Mahalingam (editor)
Aricent
India
EMail: venkat.mahalingams@gmail.com