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rfc:rfc4221

Network Working Group T. Nadeau Request for Comments: 4221 Cisco Systems, Inc. Category: Informational C. Srinivasan

                                                        Bloomberg L.P.
                                                             A. Farrel
                                                    Old Dog Consulting
                                                         November 2005
      Multiprotocol Label Switching (MPLS) Management Overview

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2005).

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.
 This document describes the management architecture for MPLS and
 indicates the interrelationships between the different MIB modules
 used for MPLS network management.

Table of Contents

 1. Introduction ....................................................3
 2. Terminology .....................................................3
 3. The SNMP Management Framework ...................................3
 4. An Introduction to the MPLS Working Group MIB Modules ...........4
    4.1. Structure of the MPLS MIB OID Tree .........................5
    4.2. MPLS-TC-STD-MIB ............................................5
    4.3. MPLS-LSR-STD-MIB ...........................................5
    4.4. MPLS-LDP-STD-MIB ...........................................6
    4.5. MPLS-LDP-GENERIC-STD-MIB ...................................6
    4.6. MPLS-LDP-ATM-STD-MIB .......................................6
    4.7. MPLS-LDP-FRAME-RELAY-STD-MIB ...............................7
    4.8. MPLS-TE-STD-MIB ............................................7
    4.9. MPLS-FTN-STD-MIB ...........................................7

Nadeau, et al. Informational [Page 1] RFC 4221 MPLS Management Overview November 2005

    4.10. TE-LINK-STD-MIB ...........................................7
    4.11. MIB Module Interdependencies ..............................8
    4.12. Dependencies on External MIB Modules ......................9
 5. Tables, Scalars, and Notifications in MPLS-LSR-STD-MIB .........10
    5.1. Tables ....................................................10
    5.2. Scalars ...................................................10
    5.3. Indexing ..................................................11
    5.4. Notifications .............................................12
    5.5. Dependencies between MIB Module Tables ....................12
 6. Tables, Scalars, and Notifications in the LDP MIB ..............13
    6.1. MIB Modules ...............................................13
    6.2. Tables ....................................................14
    6.3. Scalars ...................................................15
    6.4. Notifications .............................................15
    6.5. Dependencies between MIB Module Tables ....................15
 7. Tables, Scalars, and Notifications in MPLS-TE-STD-MIB ..........16
    7.1. Tables ....................................................16
    7.2. Scalars ...................................................17
    7.3. Notifications .............................................18
    7.4. Dependencies between MIB Module Tables ....................18
 8. Tables, Scalars, and Notifications in MPLS-FTN-STD-MIB .........18
    8.1. Tables ....................................................18
    8.2. Scalars ...................................................19
    8.3. Notifications .............................................19
    8.4. Dependencies between MIB Module Tables ....................19
 9. Tables and Objects in TE-LINK-STD-MIB ..........................19
    9.1. Tables ....................................................19
    9.2. Scalars ...................................................20
    9.3. Notifications .............................................20
    9.4. Dependencies between MIB Module Tables ....................20
 10. Table Dependencies between MPLS MIB Modules ...................21
 11. A Note on Interfaces ..........................................21
    11.1. MPLS Tunnels as Interfaces ...............................21
    11.2. Application of the Interfaces Group to TE Links ..........22
    11.3. References to Interface MIB Objects from MPLS MIB
          Modules ..................................................23
 12. Management Options ............................................24
 13. Related IETF MIB Modules ......................................25
    13.1. PWE3 Working Group MIB Modules ...........................26
    13.2. PPVPN Working Group MIB Modules ..........................26
         13.2.1. PPVPN-MPLS-VPN-STD-MIB ............................26
    13.3. CCAMP Working Group MIB Modules ..........................26
 14. Traffic Engineering Working Group TE MIB ......................27
    14.1. Choosing between TE MIB Modules ..........................27
 15. Security Considerations .......................................28
 16. Acknowledgements ..............................................28
 17. Normative References ..........................................29
 18. Informative References ........................................30

Nadeau, et al. Informational [Page 2] RFC 4221 MPLS Management Overview November 2005

1. Introduction

 This document describes the Management Architecture for Multi-
 Protocol Label Switching (MPLS) [RFC3031].  In particular, it
 describes how the managed objects defined in various MPLS-related
 Management Information Base (MIB) documents model different aspects
 of MPLS.  Furthermore, this document explains the interactions and
 dependencies between each of these MIB modules.
 For additional information, this document also includes a brief note
 on MIB modules produced by the Pseudo Wire Emulation Edge to Edge
 (PWE3), Provider Provisioned Virtual Private Network (PPVPN), Common
 Control and Measurement Plane (CCAMP), and Internet Traffic
 Engineering (TEWG) working groups.
 The document begins with a brief outline of the SNMP framework.  This
 is not intended to be a complete reference on SNMP, but is provided
 to give context to the rest of the document and to indicate reference
 material for readers that need to know more about SNMP.
 This document does not propose any additions to the MPLS MIB
 framework, nor define any standards for the Internet community.  It
 is an informational document.  In all cases, the reader is advised to
 turn to the document that defines the MIB module in question for
 further information.
 Comments should be made directly to the MPLS mailing list at
 mpls@uu.net.

2. Terminology

 This document uses terminology from the MPLS architecture document
 [RFC3031] and the following MPLS related MIB modules: MPLS TC MIB
 [TCMIB], MPLS LSR MIB [LSRMIB], MPLS TE MIB [TEMIB], MPLS LDP MIB
 [LDPMIB], MPLS FTN MIB [FTNMIB], TE LINK MIB [TELMIB], and PPVPN MPLS
 VPN MIB [VPNMIB].
 Throughout this document hyphenated MIB names (such as MPLS-TE-STD-
 MIB) should be taken to refer to specific MIB modules.  Non-
 hyphenated MIB names (such as MPLS LDP MIB) indicate MIB documents.

3. The SNMP Management Framework

 For a detailed overview of the documents that describe the current
 Internet-Standard Management Framework, please refer to section 7 of
 RFC 3410 [RFC3410].

Nadeau, et al. Informational [Page 3] RFC 4221 MPLS Management Overview November 2005

 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).  This document specifies a
 MIB module that is compliant to the SMIv2, which is described in STD
 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC
 2580 [RFC2580].

4. An Introduction to the MPLS Working Group MIB Modules

 This section addresses the MIB documents produced by the MPLS working
 group, namely MPLS TC MIB, MPLS LSR MIB, MPLS TE MIB, MPLS LDP MIB,
 MPLS FTN MIB, and TE LINK MIB.  The rest of this section briefly
 describes the following:
  1. the MPLS Object Identifier (OID) tree structure and the position

of different MPLS related MIB modules on this tree;

  1. the purpose of each of the MIB modules within the MIB documents,

what it can be used for, and how it relates to the other MIB

    modules.
 Note that each MIB document contains one or more compliance
 statements for the modules and objects that it defines.  Therefore,
 the support for the different MIB modules and objects is beyond the
 scope of this document, although some recommendations are included in
 the sections that follow.

Nadeau, et al. Informational [Page 4] RFC 4221 MPLS Management Overview November 2005

4.1. Structure of the MPLS MIB OID Tree

 The MPLS MIB OID tree has the following structure.
    transmission -- RFC 2578 [RFC2578]
      |
      +- mplsStdMIB -- MPLS-TC-STD-MIB
      |    |
      |    +- mplsTCStdMIB -- MPLS-TC-STD-MIB
      |    |
      |    +- mplsLsrStdMIB -- MPLS-LSR-STD-MIB
      |    |
      |    +- mplsTeStdMIB -- MPLS-TE-STD-MIB
      |    |
      |    +- mplsLdpStdMIB -- MPLS-LDP-STD-MIB
      |    |
      |    +- mplsLdpAtmStdMIB -- MPLS-LDP-ATM-STD-MIB
      |    |
      |    +- mplsLdpFrameRelayStdMIB -- MPLS-LDP-FRAME-RELAY-STD-MIB
      |    |
      |    +- mplsLdpGenericStdMIB -- MPLS-LDP-GENERIC-STD-MIB
      |    |
      |    +- mplsFTNStdMIB -- MPLS-FTN-STD-MIB
      |
      +- teLinkStdMIB -- TE-LINK-STD-MIB
 Note: The OIDs for MIB modules are assigned and managed by IANA.
 They can be found in the referenced MIB documents.

4.2. MPLS-TC-STD-MIB

 MPLS-TC-STD-MIB defines textual conventions [RFC2579] that may be
 common to MPLS-related MIB modules.  These conventions allow multiple
 MIB modules to use the same syntax and format for a concept that is
 shared between the MIB modules.
 For example, labels are a central part of MPLS and need to be
 presented in many of the MIB modules.  The textual convention for
 representing an MPLS label is defined in MPLS-TC-STD-MIB.
 All of the other MPLS MIB modules import textual conventions from
 this MIB module.

4.3. MPLS-LSR-STD-MIB

 MPLS-LSR-STD-MIB describes managed objects for modeling an MPLS Label
 Switching Router (LSR).  This puts it at the heart of the management
 architecture for MPLS.

Nadeau, et al. Informational [Page 5] RFC 4221 MPLS Management Overview November 2005

 This MIB module is used to model and manage the basic label switching
 behavior of an MPLS LSR.  It represents the label forwarding
 information base (LFIB) of the LSR and provides a view of the LSPs
 that are being switched by the LSR in question.
 Since basic MPLS label switching is common to all MPLS applications,
 this MIB module is referenced by many of the other MPLS MIB modules.
 In general, MPLS-LSR-STD-MIB provides a model of incoming labels on
 MPLS-enabled interfaces being mapped to outgoing labels on MPLS-
 enabled interfaces via a conceptual object called an MPLS cross-
 connect.  MPLS cross-connect entries and their properties are
 represented in MPLS-LSR-STD-MIB and are typically referenced by other
 MIB modules in order to refer to the underlying MPLS LSP.
 For example, MPLS-TE-STD-MIB models traffic-engineered tunnels.
 These tunnels map to one or more underlying MPLS LSPs.  MPLS-TE-STD-
 MIB refers to the underlying LSPs by pointing to cross-connect
 entries in MPLS-LSR-STD-MIB.

4.4. MPLS-LDP-STD-MIB

 MPLS-LDP-STD-MIB describes managed objects used to model and manage
 the MPLS Label Distribution Protocol (LDP) [RFC3036].  LDP is one of
 the MPLS protocols used to distribute labels and establish LSPs.
 This MIB module contains objects common to all LDP implementations.
 For an LDP implementation that provides standard MIB support, this
 MIB module provides the core set of objects that are needed, along
 with one or more of the other LDP MIB modules from the following
 sections.

4.5. MPLS-LDP-GENERIC-STD-MIB

 This MIB module provides objects for managing the LDP Per Platform
 Label Space and is typically implemented along with the MPLS-LDP-
 STD-MIB module.  This MIB Module contains tables for configuring MPLS
 Generic Label Ranges.  Although the LDP Specification does not
 provide a way to configure Label Ranges for Generic Labels, the MIB
 module does provide a way to reserve a range of generic labels
 because the working group thought this was useful.

4.6. MPLS-LDP-ATM-STD-MIB

 This MIB module is typically supported along with MPLS-LDP-STD-MIB by
 LDP implementations if LDP uses ATM as the Layer 2 medium.  Tables in
 this MIB module allow for configuring LDP to use ATM.

Nadeau, et al. Informational [Page 6] RFC 4221 MPLS Management Overview November 2005

4.7. MPLS-LDP-FRAME-RELAY-STD-MIB

 This MIB module is typically supported along with MPLS-LDP-STD-MIB by
 LDP implementations if LDP uses Frame Relay as the Layer 2 medium.
 Tables in this MIB module allow for configuration of LDP to use Frame
 Relay.

4.8. MPLS-TE-STD-MIB

 MPLS-TE-STD-MIB describes managed objects that are used to model and
 manage MPLS Traffic Engineered (TE) Tunnels.
 This MIB module is based on a table that represents TE tunnels that
 either originate from, traverse via, or terminate on the LSR in
 question.  The MIB module provides configuration and statistics
 objects needed for TE tunnels.

4.9. MPLS-FTN-STD-MIB

 MPLS-FTN-STD-MIB describes managed objects that are used to model and
 manage the MPLS FEC-to-NHLFE (FTN) mappings that take place at an
 ingress Label Edge Router (LER).
 An LER is an LSR placed at the edge of an MPLS domain, and it passes
 traffic into and out of the MPLS domain.  An ingress LER is
 responsible for classifying data and assigning it to a suitable LSP
 or tunnel.
 This classification is done using Forwarding Equivalence Classes
 (FECs) that define the common attributes of data (usually packets)
 that will be treated in the same way.  Once data has been classified,
 it can be handed off to an LSP or tunnel through the Next Hop Label
 Forwarding Entry (NHLFE).
 In the case of an IP-to-MPLS mapping, the FEC objects describe IP
 6-tuples that represent source and destination address ranges, source
 and destination port ranges, the IPv4 Protocol field or IPv6 next-
 header field, and the DiffServ Code Point (DSCP).

4.10. TE-LINK-STD-MIB

 TE-LINK-STD-MIB describes managed objects that are used to model and
 manage TE links, including bundled links, in an MPLS network.
 The TE link feature is designed to aggregate one or more similar data
 channels or TE links between a pair of LSRs.  A TE link is a sub-
 interface capable of carrying traffic-engineered MPLS traffic.

Nadeau, et al. Informational [Page 7] RFC 4221 MPLS Management Overview November 2005

 A bundled link is a sub-interface that bonds the traffic of a group
 of one or more TE links.

4.11. MIB Module Interdependencies

 This section provides an overview of the relationship between the
 MPLS MIB modules described above.  More details of these
 relationships are given below after the MIB modules have been
 discussed in more detail.
 The arrows in the following diagram show a 'depends on' relationship.
 A relationship "MIB module A depends on MIB module B" means 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-LDP-ATM-STD-MIB ---------->+        |
 |                                    |        |
 +<-- MPLS-LDP-FRAME-RELAY-STD-MIB -->+        |
 |                                             |
 +<------- MPLS-TE-STD-MIB ------------------->+
 |            ^                                |
 |            |                                |
 +<------- MPLS-FTN-STD-MIB ------------------>+
 Thus:
  1. All the MPLS MIB modules depend on MPLS-TC-STD-MIB.
  1. MPLS-LDP-STD-MIB, MPLS-TE-STD-MIB, and MPLS-FTN-STD-MIB contain

references to objects in MPLS-LSR-STD-MIB.

  1. MPLS-LDP-GENERIC-STD-MIB, MPLS-LDP-ATM-STD-MIB, and MPLS-LDP-

FRAME-RELAY-STD-MIB contain references to objects in MPLS-LDP-

    STD-MIB.
  1. MPLS-FTN-STD-MIB contains references to objects in MPLS-TE-STD-

MIB.

Nadeau, et al. Informational [Page 8] RFC 4221 MPLS Management Overview November 2005

 Note that there is a textual convention (MplsIndexType) defined in
 MPLS-LSR-STD-MIB that is imported by MPLS-LDP-STD-MIB.

4.12. Dependencies on External MIB Modules

 With the exception of MPLS-TC-STD-MIB, all the MPLS MIB modules have
 dependencies on the Interfaces MIB [RFC2863].  MPLS-FTN-STD-MIB
 references IP-capable interfaces on which received traffic is to be
 classified using indexes in the Interface Table (ifTable) of IF-MIB
 [RFC2863].  The other MPLS MIB modules reference MPLS-capable
 interfaces in ifTable.
 The Interfaces Group of 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 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 ifTable.
 The interrelation of entries in ifTable is defined by the Interfaces
 Stack Group defined in [RFC2863].
 Additionally, MPLS-LDP-ATM-STD-MIB imports the textual convention
 AtmVpIdentifier from ATM-TC-MIB to represent an ATM virtual path
 identifier, whereas MPLS-LDP-FRAME-RELAY-STD-MIB imports the textual
 convention DLCI from FRAME-RELAY-DTE-MIB to represent a Data Link
 Channel identifier.
 MPLS-LDP-STD-MIB imports the textual conventions IndexInteger and
 IndexIntegerNextFree from [RFC3289], and MPLS-TE-STD-MIB imports
 IndexIntegerNextFree.  IndexInteger provides a standard arbitrary
 index, whereas IndexIntegerNextFree is used by a management agent
 that needs to select an appropriate value for an arbitrary index.
 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.  This is business as usual for a MIB module
 and is not discussed further in this document.

Nadeau, et al. Informational [Page 9] RFC 4221 MPLS Management Overview November 2005

5. Tables, Scalars, and Notifications in MPLS-LSR-STD-MIB

5.1. Tables

 MPLS-LSR-STD-MIB contains the following tables.
  1. The interface configuration table (mplsInterfaceTable) is used for

enabling MPLS on MPLS-capable interfaces.

  1. The in-segment (mplsInSegmentTable) and out-segment

(mplsOutSegmentTable) tables are used to configure and monitor LSP

    segments carrying data into and out of the LSR, respectively.
  1. The in-segment mapping table (mplsInSegmentMapTable) provides a

look-up table that enables the discovery of an in-segment in

    mplsInSegmentTable from the known incoming interface and incoming
    label.
  1. The cross-connect table (mplsXCTable) is used to associate in and

out segments in order to form a cross-connect (i.e., to represent

    an LSP transiting the LSR).
  1. The label stack table (mplsLabelStackTable) allows the

specification of multi-label stacks to be imposed on a given LSP

    at this LSR.
  1. The MPLS in-segment (mplsInSegmentPerfTable) and out-segment

(mplsOutSegmentPerfTable) performance tables contain objects to

    measure the performance of LSPs.
  1. The MPLS interface performance table (mplsInterfacePerfTable) has

objects to measure MPLS performance on a per-interface basis.

5.2. Scalars

 Where tables in the MIB module have arbitrary indexes, scalars are
 provided to supply the next available index.  This applies to
 mplsInSegmentTable, mplsOutSegmentTable, mplsXCTable, and
 mplsLabelStackTable, but see the section on indexing, below.
 mplsMaxLabelStackDepth defines the maximum size of a imposed label
 stack supported at this LSR (and not, as the description in MPLS-
 LSR-STD-MIB states, the maximum label stack depth supported by the
 LSR).
 mplsXCNotificationsEnable is used to enable and disable notifications
 from MPLS-LSR-STD-MIB.

Nadeau, et al. Informational [Page 10] RFC 4221 MPLS Management Overview November 2005

5.3. Indexing

 Note that the indexing used by the tables in MPLS-LSR-STD-MIB is
 unusual.  A specific textual convention, MplsIndexType, is defined in
 the MIB module and is used as the type for indexes to
 mplsInSegmentTable, mplsOutSegmentTable, mplsXCTable, and
 mplsLabelStackTable.  The textual convention is defined as an octet
 string of between one and twenty-four octets, inclusive.
 Although this convention can be used to map simple integers and so
 preserve the normal indexing techniques, it may also be used to
 encode more complex indexing rules that may be useful to
 implementations that subdivide their label spaces according to
 physical or implementation constraints (such as placing the
 responsibility for a subset of labels with a line card).
 Note that it would be unusual, but not impossible, to make
 sophisticated use of these indexes in a write-access MIB since the
 'next' index value would be hard to determine.  Thus, non-simple
 values are likely only to be used in read-only MIBs in which the
 indexes are generated as a result of signaling protocol
 implementations or other configuration means.  The formatting and
 interpretation of non-simple indexes is out of the scope of the MIB
 module definition and is expected to be part of the manageability
 statement for a particular device.  When the formatting is not known
 by an agent, it should treat the index as a plain octet string
 containing an integer of between one and twenty-four octets.
 As described in the previous section, scalars are provided to allow
 agents to discover a suitable value to use as an index when creating
 a new row in one of these tables.  These scalars all use a second
 textual convention, MplsIndexNextType, also defined within MPLS-LSR-
 STD-MIB.  This textual convention allows the 'null string', (that is,
 a string of length one octet with value 0x00).  The null string is
 used to indicate that either write access is not supported or no more
 indexes are currently available.
 Note that the usage of the nextIndex scalars is such that at any time
 a scalar supplies a value that is currently unused as an index to the
 specific table.  In order to avoid lacunae in the indexing of a table
 under normal usage, implementations are recommended to change the
 value in an nextIndex scalar only when the index is used (that is,
 when a row is created) and not when the nextIndex scalar is read.  In
 a 'busy' table, this may result in row creation attempts failing and
 agents having to re-read the scalar before making a second row
 creation attempt.  The desire to avoid this issue is in opposition to
 the desire to avoid lacunae.

Nadeau, et al. Informational [Page 11] RFC 4221 MPLS Management Overview November 2005

5.4. Notifications

 MPLS-LSR-STD-MIB can issue two notifications (if notifications are
 enabled).
  1. mplsXCUp reports when a cross-connect becomes active.
  1. mplsXCDown reports when a cross-connect becomes

inactive.

5.5. Dependencies between MIB Module Tables

 The tables in MPLS-LSR-STD-MIB are related as shown on the diagram
 below.  The arrows indicate a reference from one table to another.
 Note that the various MIB tables contain two instances of pointers to
 external tables that are not currently defined.  Entries in an
 external Traffic Parameters Table (external_Traffic_Table) are
 pointed to using RowPointers from the mplsInSegmentTable
 (mplsInSegmentTrafficParamPtr) and from the mplsOutSegmentTable
 (mplsOutSegmentTrafficParamPtr) to allow representation of the
 traffic parameters for the MPLS segment.  Alternatively, the pointers
 may indicate an entry in the Tunnel Resource Table
 (mplsTunnelResourceTable) in MPLS-TE-STD-MIB.  Similarly, an external
 label table may be used to store label values if, for some reason,
 they are not stored in place within the LSR MIB tables.  This might
 occur if extra per-label space information needs to be stored, and it
 paves the way for GMPLS where labels cannot always be stored in a
 32-bit value.  RowPointers are used from the mplsInSegmentTable
 (mplsInSegmentLabelPtr), the mplsOutSegmentTable
 (mplsOutSegmentTopLabelPtr), and from the mplsLabelStackTable
 (mplsLabelStackLabelPtr).

Nadeau, et al. Informational [Page 12] RFC 4221 MPLS Management Overview November 2005

                    mplsInterfacePerfTable
                               ^
                               |
                               V
                      mplsInterfaceTable
                       ^              ^
 mplsInSegmentMapTable |              | mplsLabelStackTable
           |           |              |           ^     |
           |      +----+              +----+      |     |
           |      |                        |      |     |
           |      | external_Traffic_Table |      |     |
           |      |   ^                ^   |      |     |
           V      |   |                |   |      |     |
          mplsInSegmentTable        mplsOutSegmentTable |
           |  ^   ^                        ^   ^     |  |
           |  |   |                        |   |     |  V
    +------+  |   +----> mplsXCTable  <----+   |     +--+
    |         V                                V        |
    | mplsInSegmentPerfTable    mplsOutSegmentPerfTable |
    |                                                   |
    +--------------> external_Label_Table <-------------+

6. Tables, Scalars, and Notifications in the LDP MIB

6.1. MIB Modules

 The MIB document for LDP contains four MIB modules.  This structure
 makes it easier for an implementation to select only those modules
 that are relevant to it.  The MIB Modules are MPLS-LDP-STD-MIB,
 MPLS-LDP-GENERIC-STD-MIB, MPLS-LDP-ATM-STD-MIB, and MPLS-LDP-FRAME-
 RELAY-STD-MIB.
 MPLS-LDP-STD-MIB defines objects that are specific to LDP without any
 Layer 2 objects.  MPLS-LDP-GENERIC-STD-MIB defines Layer 2 Per
 Platform Label Space objects for use with MPLS-LDP-STD-MIB and for
 use on Ethernet.  MPLS-LDP-ATM-STD-MIB defines Layer 2 Asynchronous
 Transfer Mode (ATM) objects for use with MPLS-LDP-STD-MIB.  MPLS-
 LDP-FRAME-RELAY-STD-MIB defines Layer 2 FRAME-RELAY objects for use
 with MPLS-LDP-STD-MIB.
 The MPLS-LDP-STD-MIB module provides the core support and is
 typically supported along with at least one of the Layer 2 MIB
 modules.

Nadeau, et al. Informational [Page 13] RFC 4221 MPLS Management Overview November 2005

6.2. Tables

 The tables in the LDP MIB for configuring the LDP behavior of an LSR
 are as follows.
  1. The LDP Entity Table (mplsLdpEntityTable) provides a way to

configure the LSR for using LDP. There must be at least one LDP

    Entity for the LSR to support LDP.  Each entry/row in this table
    represents a single LDP Entity.
  1. Several tables exist to help configure LDP's use of labels. These

are spread through the MIB modules described in the previous

    section.  They are: mplsLdpEntityGenLRTable,
    mplsLdpEntityAtmParmsTable and mplsLdpEntityAtmLRTable,
    mplsLdpEntityFrameRelayParmsTable and mplsLdpEntityFrLRTable.
    They are used to configure generic, ATM, and Frame Relay labels as
    their names suggest.
  1. The LDP Peer Table (mplsLdpPeerTable) is a read-only table that

contains information about LDP Peers known to LDP Entities.

  1. The LDP Hello Adjacencies Table (mplsLdpHelloAdjacencyTable) is a

table of all adjacencies between all LDP Entities and all LDP

    Peers.
  1. Several tables exist to monitor and control LDP sessions. The LDP

Session Table (mplsLdpSessionTable) represents sessions between an

    LDP Entity and a Peer.  mplsLdpAtmSesTable and
    mplsLdpFrameRelaySesTable contain session information specific to
    ATM.
  1. The MPLS LDP Session Peer Address Table (mplsLdpSesPeerAddrTable)

stores addresses learned after session initialization via Address

    Message advertisement.
  1. The LDP FEC Table (mplsFecTable) represents FEC (Forwarding

Equivalence Class) information that may be in use on one or more

    LSPs.  The LDP LSP FEC Table (mplsLdpLspFecTable) shows the FECs
    associated with each LSP.
  1. MPLS-LDP-STD-MIB has a mapping table (mplsLdpLspTable) that maps

the LDP MIB's representation of LDP sessions to the underlying LSR

    MIB's representation of the LSPs created by these sessions, by
    pointing to mplsInSegmentTable, mplsOutSegmentTable, and
    mplsXCTable, respectively.

Nadeau, et al. Informational [Page 14] RFC 4221 MPLS Management Overview November 2005

  1. Statistics may be gathered through the LDP Entity Statistics Table

(mplsLdpEntityStatsTable) and the LDP Session Statistics Table

    (mplsLdpSesStatsTable).

6.3. Scalars

 Where tables in the MIB modules have arbitrary indexes, scalars are
 provided to supply the next available index.  This applies to
 mplsLdpEntityTable and mplsFecTable.
 Two scalars exist to configure the LSR.  The LSR ID is set in
 mplsLdpLsrId, and the loop detection capabilities are reported in
 mplsLdpLsrLoopDetectionCapable.

6.4. Notifications

 MPLS-LDP-STD-MIB defines four notifications that a device can issue.
  1. mplsLdpInitSesThresholdExceeded is reported when the number of

Session Initialization messages exceeds a configured threshold.

  1. mplsLdpPVLMismatch is issued if the Path Vector Limit for a

configured Entity and Peer do not match.

  1. mplsLdpSessionUp and mplsLdpSessionDown report the transition of

Session state.

 No scalar object is provided to enable and disable notifications from
 MPLS-LDP-STD-MIB.  Instead, the implementer is referred to [RFC3413].

6.5. Dependencies between MIB Module Tables

 The many tables in the four LDP MIB modules are related as shown on
 the diagram below.  The arrows indicate a reference from one table to
 another.  Note that in many cases the reference is through an
 augmentation of the referenced table.

Nadeau, et al. Informational [Page 15] RFC 4221 MPLS Management Overview November 2005

 mplsLdpEntityGenLRTable ------------->+
 mplsLdpEntityAtmParmsTable ---------->+
 mplsLdpEntityAtmLRTable ------------->+
 mplsLdpEntityFrameRelayParmsTable --->+
 mplsLdpEntityFrLRTable -------------->+
 mplsLdpEntityStatsTable ------------->+
                                       |
 mplsLdpHelloAdjacencyTable            |
              |                        |
              |  mplsLdpEntityTable <--+
              |      ^       ^
              V      |       |
          mplsLdpPeerTable <-+- mplsLdpSesPeerAddrTable
                     ^       |
                     |       V
               mplsLdpSessionTable
                            ^   ^
                            |   |
 mplsLdpSesStatsTable ------+   +-- mplsLdpLspFecTable
 mplsLdpAtmSesTable --------+   |    |       |
 mplsLdpFrameRelaySesTable--+   |    |       V
                                |    |    mplsFecTable
                                |    V
                                +-- mplsLdpLspTable

7. Tables, Scalars, and Notifications in MPLS-TE-STD-MIB

7.1. Tables

 MPLS-TE-STD-MIB contains the following tables.
  1. The Tunnel Table (mplsTunnelTable) is used to configure and report

MPLS tunnels. Note that reporting of tunnels in this table at

    transit LSRs is optional.
    Entries in mplsTunnelTable are indexed by four objects.  The
    source and destination LSR IDs give context to the entry, and an
    index  (mplsTunnelIndex) identifies the tunnel itself.  However,
    the fourth index (mplsTunnelInstance) may give rise to some
    confusion since its usage is not clearly explained.
    The description says: "Uniquely identifies an instance of a
    tunnel.  It is useful to identify multiple instances of tunnels
    for the purposes of backup and parallel tunnels." In the case of
    backup tunnels, multiple instances of the same tunnel may be
    defined, but only one is active at any time.  Different instances
    may have different properties (such as explicit routes), and one
    instance may be set up to protect against failure of another.

Nadeau, et al. Informational [Page 16] RFC 4221 MPLS Management Overview November 2005

    Parallel tunnels may be used to provide load sharing or
    protection.
    The mplsTunnelInstancePriority object is used to indicate the
    precedence of tunnels with the same LSR IDs and mplsTunnelIndex
    value.  The mplsTunnelPrimaryInstance object gives a quick
    reference back to the preferred instance of the tunnel.
    The mplsTunnelIndex value is typically signaled as the Tunnel ID,
    and the mplsTunnelInstance as the LSP ID, in protocols where both
    fields exist.  In protocols where there is only one identifying
    index (usually known as the LSP ID), only the mplsTunnelIndex is
    signaled.
  1. The Resource Table (mplsTunnelResourceTable) is used to configure

resources to be requested on this tunnel. The CRLDP resource

    table (mplsTunnelCRLDPResTable) is used to request additional
    resource details that are specific to tunnels signaled using CR-
    LDP.
  1. The routes requested, computed, and actually used for a tunnel are

found in the Tunnel Hop Table (mplsTunnelHopTable), Tunnel

    Computed Hop Table (mplsTunnelCHopTable), and Tunnel Actual Hop
    Table (mplsTunnelARHopTable).
  1. Statistics about the performance of tunnels may be gathered

through the Tunnel Performance Table (mplsTunnelPerfTable).

7.2. Scalars

 Where tables in the MIB module have arbitrary indexes, scalars are
 provided to supply the next available index.  This applies to
 mplsTunnelTable, mplsTunnelResourceTable, and mplsTunnelHopTable.
 Two scalars exist to configure the support for MPLS tunnels on the
 LSR.  mplsTunnelTEDistProto lists the signaling methods and protocols
 supported.  mplsTunnelMaxHops defines the size of route that may be
 configured on the LSR.
 Two further scalars enhance the statistics on the LSR by counting the
 number of configured (mplsTunnelConfigured) and active
 (mplsTunnelActive) tunnels.
 The scalar mplsTunnelNotificationMaxRate is used to control the rate
 at which notifications are issued from MPLS-TE-STD-MIB.  A rate of
 zero means that notifications must not be issued.  If notifications

Nadeau, et al. Informational [Page 17] RFC 4221 MPLS Management Overview November 2005

 would be generated faster than the configured rate, an implementation
 may choose to discard notifications or to queue them for distribution
 at a quieter time.

7.3. Notifications

 MPLS-TE-STD-MIB defines four notifications that a device can issue.
 The rate of dispatch of notifications is controlled as described in
 the previous section.
  1. mplsTunnelUp and mplsTunnelDown report the transition of Tunnel

state.

  1. Rerouting and re-optimization of Tunnels paths are reported by

mplsTunnelRerouted and mplsTunnelReoptimized.

7.4. Dependencies between MIB Module Tables

 The tables in MPLS-TE-STD-MIB are related as shown on the diagram
 below.  The arrows indicate a reference from one table to another.
                      mplsTunnelPerfTable
                              ^
                              |
                              V
                       mplsTunnelTable
                           |      |
                           V      |
      mplsTunnelResourceTable     +--> mplsTunnelHopTable
            ^                     |
            |                     +--> mplsTunnelCHopTable
            V                     |
 mplsTunnelCRLDPResTable          +--> mplsTunnelARHopTable

8. Tables, Scalars, and Notifications in MPLS-FTN-STD-MIB

8.1. Tables

 MPLS-FTN-STD-MIB contains the following tables.
  1. The FEC-to-NHLFE Table (mplsFTNTable) defines the FEC to NHLFE

rules to be applied to incoming packets, and the actions to be

    taken on matching packets.
  1. The FEC-to-NHLFE Mapping Table (mplsFTNMapTable) provides the

capability to activate FTN rules defined in the mplsFTNTable on

    specific interfaces in the system.

Nadeau, et al. Informational [Page 18] RFC 4221 MPLS Management Overview November 2005

  1. Performance statistics for FTN rules are found in the

mplsFTNPerfTable.

8.2. Scalars

 This MIB module contains the scalars mplsFTNTableLastChanged and
 mplsFTNMapTableLastChanged to indicate the last time an object
 changed in mplsFTNTable and mplsFTNMapTable, respectively.  Another
 scalar, mplsFTNIndexNext, is used to supply the next valid index for
 creating new conceptual rows in mplsFTNTable.

8.3. Notifications

 There are no notifications in this MIB module.

8.4. Dependencies between MIB Module Tables

 The tables in MPLS-FTN-STD-MIB are related as shown on the diagram
 below.  The arrows indicate a reference from one table to another.
                       mplsFTNTable
                            ^
                            |
                     mplsFTNMapTable
                            ^
                            |
                     mplsFTNPerfTable

9. Tables and Objects in TE-LINK-STD-MIB

9.1. Tables

 TE-LINK-STD-MIB contains the following tables.
  1. The TE link table (teLinkTable) is used to specify TE links,

including bundled links, and their generic traffic-engineering

    parameters.
  1. The TE link descriptor table (teLinkDescriptorTable) is used to

list the TE link descriptors.

  1. The shared risk link group (SRLG) table (teLinkSrlgTable) is used

to specify the SRLGs associated with TE links.

  1. The TE link bandwidth table (teLinkBandwidthTable) is used to

report priority-based bandwidth values associated with TE links.

Nadeau, et al. Informational [Page 19] RFC 4221 MPLS Management Overview November 2005

  1. The component link table (componentLinkTable) is used to identify

the data-bearing component links that are associated with the TE

    links and specify the data-bearing link generic traffic
    engineering parameters.
  1. The component link descriptor table (componentLinkDescriptorTable)

is used to list the data-bearing component link descriptors.

  1. The component link bandwidth table (componentLinkBandwidthTable)

is used to report priority-based bandwidth values associated with

    data-bearing component links.

9.2. Scalars

 There are no scalars in this MIB module.

9.3. Notifications

 There are no notifications in this MIB module.

9.4. Dependencies between MIB Module Tables

 The tables in TE-LINK-STD-MIB are related as shown on the diagram
 below.  The arrows indicate a reference from one table to another.
 Note that many of the associations between tables are through a
 common index that is the ifIndex of the related interface.
                 teLinkTable
                          ^
                          |
 teLinkDescriptorTable ---+
                          |
 teLinkSrlgTable ---------+
                          |
 teLinkBandwidthTable ----+
                 componentLinkTable
                                 ^
                                 |
 componentLinkDescriptorTable ---+
                                 |
 componentLinkBandwidthTable ----+

Nadeau, et al. Informational [Page 20] RFC 4221 MPLS Management Overview November 2005

10. Table Dependencies between MPLS MIB Modules

 Section 4.11 gave an overview of how the MPLS MIB modules are
 related.  Now that the tables in the MIB modules have been
 introduced, it is possible to give a more detailed diagram of these
 relationships.
 MPLS-TC-STD-MIB is left off the diagram because many of the MIB
 module tables use textual conventions from that MIB module.
           mplsLsrXCTable   mplsLsrInSegmentTable
                       ^     ^
                       |     |
                       +---- mplsLdpLspTable
                       |     |
 mplsTunnelTable ------+     V
    ^                  |    mplsLsrOutSegmentTable
    |                  |
 mplsFTNTable ---------+

11. A Note on Interfaces

 The Interfaces Group of IF-MIB [RFC2863] defines generic managed
 objects for managing interfaces.  The MPLS MIB modules make
 references to interfaces so that it can be clearly determined where
 the procedures managed by the MIB modules should be performed.
 Additionally, the MPLS MIB modules (notably MPLS-TE-STD-MIB and TE-
 LINK-STD-MIB) utilize interface stacking within the Interface Group.

11.1. MPLS Tunnels as Interfaces

 MPLS-TE-STD-MIB builds on the concept of managing MPLS Tunnels as
 logical interfaces.  [RFC2863] states that the interfaces table
 (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, an MPLS Tunnel managed
 as an interface is represented as an entry in the ifTable.  The
 interrelation of entries in the ifTable is defined by the Interfaces
 Stack Group defined in [RFC2863].
 When using MPLS Tunnels as interfaces, the interface stack table
 might appear as follows:

Nadeau, et al. Informational [Page 21] RFC 4221 MPLS Management Overview November 2005

 +------------------------------------------------+
 | MPLS tunnel interface ifType = mplsTunnel(150) |
 +------------------------------------------------+
 |        MPLS interface ifType = mpls(166)       |
 +------------------------------------------------+
 |               Underlying layer                 |
 +------------------------------------------------+
 In the diagram above, "Underlying layer" refers to the ifIndex of any
 interface type for which MPLS internetworking has been defined.
 Examples include ATM, Frame Relay, and Ethernet.
 A detailed listing of the mapping between ifTable objects and their
 use for MPLS Tunnels is given in [TEMIB].  A few key objects are
 listed here to provide an overview of the concepts.
 Each MPLS tunnel is represented by an entry in the ifTable.  Each
 tunnel is therefore assigned a unique ifIndex.
 The type of an interface represented by an entry in the ifTable is
 indicated by the ifType object.  The value that is allocated to
 identify an MPLS tunnel is 150.
 The ifOperStatus object reflects the actual operational status of the
 MPLS tunnel and may be mapped from the mplsTunnelOperStatus object.
 It may be considered convenient and good management to set the ifName
 object to reflect the name of the MPLS tunnel as contained in the
 mplsTunnelName object.

11.2. Application of the Interfaces Group to TE Links

 TE-LINK-STD-MIB also uses interface stacking to manage TE Link
 interfaces as logical interfaces.  The TE Link interface is
 represented as an entry in the ifTable.  The interrelation of entries
 in the ifTable is defined by Interfaces Stack Group defined in
 [RFC2863].  When using TE Link interfaces, the interface stack table
 might appear as follows:

Nadeau, et al. Informational [Page 22] RFC 4221 MPLS Management Overview November 2005

 +-------------------------------------------------------------------+
 | MPLS interface ifType = mpls(166)                                 |
 | ifIndex = 1                                                       |
 +-------------------------------------------------------------------+
 | TE link (bundled link) ifType = teLink(200)                       |
 | ifIndex = 2                                                       |
 +--------------------------------+-+--------------------------------+
 | TE link ifType = teLink(200)   | | TE link ifType = teLink(200)   |
 | ifIndex = 3                    | | ifIndex = 4                    |
 +--------------------------------+ +--------------------------------+
 | Component link                 | | Component link                 |
 | ifType = opticalTransport(196) | | ifType = opticalTransport(196) |
 | ifIndex = 5                    | | ifIndex = 6                    |
 +--------------------------------+ +--------------------------------+
 In the above diagram, "opticalTransport" is an example of an
 underlying physical interface: in this case an optical transport
 interface.  TE link management and bundling can be seen in the levels
 of interface stacking.  Two TE links are defined, each managing an
 optical transport link.  These two TE links are combined into a
 bundle, which is managed as a single TE link interface.  This TE Link
 interface supports MPLS and is presented as an MPLS interface.
 A detailed listing of the mapping between ifTable objects and their
 use for TE Links is given in [TELMIB].  A few key objects are listed
 here to provide an overview of the concepts.
 Each TE Link interface is represented by a separate entry in the
 ifTable, with a unique ifIndex.
 The type of an interface represented by an entry in the ifTable is
 indicated by the ifType object.  The value that is allocated to
 identify a TE Link is 200.

11.3. References to Interface MIB Objects from MPLS MIB Modules

 MPLS-TE-STD-MIB contains two objects that reference the management of
 an MPLS tunnel as an interface.  mplsTunnelIsIf is a TruthValue that
 indicates whether the tunnel is present in the ifTable.  If the
 tunnel is managed as an interface, the mplsTunnelIfIndex object
 contains the ifIndex that identifies the corresponding entry in the
 ifTable.
 MPLS-LSR-STD-MIB includes a table (mplsInterfaceTable) for
 configuring the support for MPLS on specific interfaces.  A
 conceptual row in this table is created automatically by an LSR for
 every interface that is capable of and configured for support of
 MPLS.  A conceptual row in this table will exist if and only if a

Nadeau, et al. Informational [Page 23] RFC 4221 MPLS Management Overview November 2005

 corresponding entry in ifTable exists with ifType = mpls(166).  The
 fate of the entries in the two tables are closely linked so that if
 the entry in the ifTable is operationally disabled, the entry in
 mplsInterfaceTable is deleted.  During the life of an entry in
 mplsInterfaceTable, a corresponding entry is managed in
 mplsInterfacePerfTable to show performance counters for the MPLS-
 capable interface.
 The ifIndex that identifies MPLS-capable interfaces also plays an
 important indexing role in MPLS-LSR-STD-MIB.  In-segments (that is,
 incoming LSP labels) are represented in mplsInSegmentTable, which is
 indexed by the mplsInSegmentIfIndex and mplsInSegmentLabel objects.
 mplsInSegmentIfIndex is set to the ifIndex of the incoming MPLS-
 capable interface.  mplsInSegmentLabel identifies the incoming MPLS
 label.  Note that the corresponding mplsOutSegmentTable contains an
 mplsOutSegmentIfIndex object to identify the outgoing MPLS-capable
 interface, but that this does not form part of the index of the
 table.
 MPLS-LDP-STD-MIB uses ifIndex extensively to identify the interface
 over which MPLS is active.
 Within MPLS-FTN-STD-MIB, mplsFTNMapTable maps entries in mplsFTNTable
 to interfaces on which mplsFTNTable entries should be activated.
 Interfaces are identified using their ifIndex values.

12. Management Options

 It is not the intention of this document to provide instructions or
 advice to implementers of Management Stations, 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.
 All MPLS LSPs may appear in MPLS-LSR-STD-MIB.  At transit nodes, they
 are seen as full cross-connects between incoming labels on incoming
 interfaces and outgoing labels on outgoing interfaces.  At ingress or
 egress points, the cross-connections are unbalanced having spoof
 upstream or downstream legs, respectively.
 Split and merge points of LSPs may be represented as more complex
 cross-connects in MPLS-LSR-STD-MIB.  Similarly, bidirectional LSPs
 can be represented by using the same cross-connect index for each of
 the forward and reverse cross-connections.
 The modules in the LDP MIB are intended solely for use with LDP and
 CR-LDP.  LSPs that are signaled through other means may conveniently
 be stored in mplsLdpLspTable for consistency with LSPs set up using

Nadeau, et al. Informational [Page 24] RFC 4221 MPLS Management Overview November 2005

 LDP, but there is little further value to this because the table
 gives only pointers into MPLS-LSR-STD-MIB.  If, however, the LSPs are
 established with associated FECs using some signaling method other
 than LDP (for example, BGP), it may be advantageous to use
 mplsLdpLspTable, mplsFecTable, and mplsLdpLspFecTable to correlate
 the LSPs.
 Note that if CR-LDP is the signaling protocol, there is no
 requirement to use the LSP-related tables in the LDP MIB since the
 LSP will be adequately represented in MPLS-TE-MIB and MPLS-LSR-STD-
 MIB.
 MPLS tunnels may be represented in MPLS-TE-STD-MIB with their cross-
 connects indicated in MPLS-LSR-STD-MIB.  Tunnels are often (although
 not always) set up with a series of constraints that may be
 represented in MPLS-TE-STD-MIB.  Note that a distinguishing feature
 of a tunnel is that it has an ingress and an egress, where LSPs
 established through LDP may be end-to-end or may be hop-by-hop.
 All LSPs (tunnels and non-tunnels) may be established as a result of
 signaling protocols already defined or for future study.  In
 addition, LSPs may be set up manually by issuing configuration
 commands to each of the LSRs on the LSP.  These commands may utilize
 SNMP by performing SET operations to the MIB module tables and
 objects described here.  Alternatively, configuration may be through
 some non-standard interface such as a Command Line or a Graphical
 User Interface.  Such configured LSPs may also be represented in the
 MIB module tables.
 Do not be misled by considerations of the "permanence" of LSPs when
 deciding which tables of which MIB modules to use.  An MPLS tunnel
 may have a very long life expectancy if it is set up by an amnesiac
 user.  Otherwise, it may have a very short lifetime if it is
 automatically provisioned to satisfy on-demand traffic requirements.
 Similarly, an LSP established in response to a routing protocol
 (sometimes known as a hop-by-hop LSP) may be equally stable or
 unstable.

13. Related IETF MIB Modules

 This section describes the broad interactions between MIB modules
 produced by the PWE3, PPVPN, and CCAMP working groups and the MPLS
 MIB modules.  This information is provided as background and is not
 central to this document.

Nadeau, et al. Informational [Page 25] RFC 4221 MPLS Management Overview November 2005

13.1. PWE3 Working Group MIB Modules

 The PWE3 working group has produced a document [PWE3FW] that includes
 a description of the framework for MIB modules within PWE3 operation.
 Since the PWE3 architecture includes the use of MPLS as an emulated
 service and as a PSN service, the MPLS MIB modules described above
 may be leveraged.  The PWE3 framework document describes the
 interactions between the MPLS MIB modules and the PWE3 MIB modules.

13.2. PPVPN Working Group MIB Modules

 At present, the PPVPN working group has not included a discussion of
 how the MPLS MIB modules interact with the MIB modules being produced
 by that working group.  The authors of this document hope to make a
 forthcoming addition to the PPVPN framework document [PPVPNFW]
 detailing these interactions.  At the moment, there are two MIB
 modules, [VPNMIB] and [VPNTCMIB], which are discussed next.

13.2.1. PPVPN-MPLS-VPN-STD-MIB

 PPVPN-MPLS-VPN-STD-MIB describes managed objects that are used to
 model and manage RFC2547bis MPLS VPNs [RFC2547Bis].  This MIB module
 contains tables that model virtual routing forwarding entries (VRFs),
 as well as the interfaces associated with those VRFs.

13.2.1.1. Position in the OID Tree

    transmission -- RFC 2578 [RFC2578]
      |
      +- vpnMIB -- PPVPN-MPLS-VPN-STD-MIB

13.2.1.2. Dependencies

 This MIB module currently has no direct dependencies on any of the
 MPLS MIB modules.  This MIB module models MPLS VPN interfaces as
 entries in the Interfaces MIB's Interfaces Table (ifTable).  This MIB
 module may be modified in the future to import textual conventions
 from MPLS-TC-STD-MIB.
 A specific textual conventions MIB module [VPNTCMIB] defines textual
 conventions that are imported into PPVPN-MPLS-VPN-STD-MIB.

13.3. CCAMP Working Group MIB Modules

 The CCAMP working group is developing MIB modules in support of GMPLS
 that interact directly with the MPLS MIB modules.  Along with any MIB
 modules produced by the CCAMP working group, a separate CCAMP-

Nadeau, et al. Informational [Page 26] RFC 4221 MPLS Management Overview November 2005

 specific Management Framework document is expected to be issued
 describing the relationship between these MIB modules and the
 existing MPLS (and other) MIB modules.

14. Traffic Engineering Working Group TE MIB

 The TEWG has produced a traffic engineering MIB (TE-MIB) [TEWGMIB]
 containing objects for monitoring traffic-engineered tunnels at their
 ingress points.
 In many senses TE-MIB contains the same information as MPLS-TE-STD-
 MIB.  Both MIB modules can be used to monitor MPLS tunnels; however,
 TE-MIB is minimalistic and caters best to TE tunnels as tunnels, at
 the expense of not having many advanced features of MPLS-TE-STD-MIB,
 whereas MPLS-TE-STD-MIB can deconstruct tunnels into hop-by-hop
 cross-connects, at the expense of more complexity.
 The TE-MIB module imports textual conventions from the MPLS-TC-STD-
 MIB module and therefore is dependent on that document.

14.1. Choosing between TE MIB Modules

 TE-MIB is a flexible MIB module designed to manage traffic
 engineering tunnels regardless of the implementation technology.
 This flexibility and a focus on simplicity lead to some compromises.
  1. Some MPLS configuration parameters are left out. For example, the

resource management in TE-MIB is confined to bandwidth, so missing

   the full IntServ control.
  1. Other TE-MIB parameters are present but with only limited options;

for example, the ability to configure different label distribution

   methods per LSP.
 Extensibility of TE-MIB to related concepts (such as DiffServ and
 Fast Reroute) and integrations with other MIB modules (such as that
 in MPLS-LSR-STD-MIB) are not work items at the time of writing.  The
 MPLS MIB modules are more closely integrated as described in this
 document.
 Write/create access to TE-MIB is only available at the ingress, where
 it can be used to configure an ingress to signal a tunnel with
 constraints.  It cannot be used to configure hop-by-hop cross-
 connects to build a tunnel.
 The purpose of TE-MIB module is to allow a Management Agent to
 configure tunnels, and to inspect and monitor all tunnels (however
 created) at their ingress points.  It does not provide information

Nadeau, et al. Informational [Page 27] RFC 4221 MPLS Management Overview November 2005

 about tunnels at any other point in the network (that is, at transit
 or egress nodes).  This module can be used, for example, to configure
 the constraints of a tunnel, whereupon the ingress would compute the
 tunnel path and signal it.  The MIB module can then be used at the
 ingress to monitor the tunnel's path(s), their status, and the
 tunnel's uptime and counters.  This MIB module is not designed to
 configure hop-by-hop cross-connects to build a tunnel.

15. Security Considerations

 This document describes the interrelationships amongst the different
 MIB modules relevant to MPLS management and as such does not have any
 security implications in and of itself.
 Each specific MIB document specifies specific MIB objects, and such a
 document 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 and GET (read) the objects in
 this MIB.  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 this MIB is properly
 configured to give access to only those objects, and to those
 principals (users) that have legitimate rights to access them.

16. Acknowledgements

 Many small pieces of text in this document have been borrowed from
 the documents that define the MIB modules described here.  The
 authors would like to express appreciation to all who worked on those
 MIB documents.
 Thanks also to all those who attended the November 2002 MPLS MIB open
 meeting and gave constructive feedback, and in particular to Sharon
 Chisholm for her thoughts on Management Options.
 Thanks to Kireeti Kompella for revising the text on TE-MIB.

Nadeau, et al. Informational [Page 28] RFC 4221 MPLS Management Overview November 2005

 Without the consistent pressure and encouragement from Bert Wijnen,
 this document would not have been written.

17. Normative References

 [FTNMIB]      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.
 [LDPMIB]      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.
 [LSRMIB]      Srinivasan, C., Viswanathan, A., and T. Nadeau,
               "Multiprotocol Label Switching (MPLS) Label Switching
               Router (LSR) Management Information Base (MIB)", RFC
               3813, June 2004.
 [RFC2863]     McCloghrie, K. and F. Kastenholtz, "The Interfaces
               Group MIB ", RFC 2863, June 2000.
 [RFC3289]     Baker, F., Chan, K., and A. Smith, "Management
               Information Base for the Differentiated Services
               Architecture", RFC 3289, May 2002.
 [TCMIB]       Nadeau, T. and J. Cucchiara, "Definitions of Textual
               Conventions (TCs) for Multiprotocol Label Switching
               (MPLS) Management", RFC 3811, June 2004.
 [TELMIB]      Dubuc, M., Dharanikota, S., Nadeau, T., J. Lang,
               "Traffic Engineering Link Management Information Base",
               RFC 4220, November 2005.
 [TEMIB]       Srinivasan, C., Viswanathan, A., and T. Nadeau,
               "Multiprotocol Label Switching (MPLS) Traffic
               Engineering (TE) Management Information Base (MIB)",
               RFC 3812, June 2004.

Nadeau, et al. Informational [Page 29] RFC 4221 MPLS Management Overview November 2005

18. Informative References

 [PPVPNFW]     Callon, R. and M. Suzuki, "A Framework for Layer 3
               Provider-Provisioned Virtual Private Networks
               (PPVPNs)", RFC 4110, July 2005.
 [PWE3FW]      Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-
               to-Edge (PWE3) Architecture", RFC 3985, March 2005.
 [RFC2026]     Bradner, S., "The Internet Standards Process --
               Revision 3", BCP 9, RFC 2026, October 1996.
 [RFC2547Bis]  Rosen, E., et al., "MPLS/BGP VPNs", Work in Progress,
               October 2002.
 [RFC2578]     McCloghrie, K., Perkins, D., and J. Schoenwaelder,
               "Structure of Management Information Version 2
               (SMIv2)", STD 58, RFC 2578, April 1999.
 [RFC2579]     McCloghrie, K., Perkins, D., and J. Schoenwaelder,
               "Textual Conventions for SMIv2", STD 58, RFC 2579,
               April 1999.
 [RFC2580]     McCloghrie, K., Perkins, D., and J. Schoenwaelder,
               "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.
 [RFC3036]     Andersson, L., Doolan, P., Feldman, N., Fredette, A.,
               and B. Thomas, "LDP Specification", RFC 3036, 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.
 [RFC3413]     Levi, D., Meyer, P., and B. Stewart, "Simple Network
               Management Protocol (SNMP) Applications", STD 62, RFC
               3413, 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.

Nadeau, et al. Informational [Page 30] RFC 4221 MPLS Management Overview November 2005

 [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.
 [TEWGMIB]     Kompella, K., "A Traffic Engineering (TE) MIB", RFC
               3970, January 2005.
 [VPNMIB]      Nadeau, T., et al., "MPLS/BGP Virtual Private Network
               Management Information Base Using SMIv2", Work in
               Progress, November 2002.
 [VPNTCMIB]    Schliesser, B. and T. Nadeau, "Definition of Textual
               Conventions for Provider Provisioned Virtual Private
               Network (PPVPN) Management", Work in Progress, November
               2002.

Authors' Addresses

 Thomas D. Nadeau
 Cisco Systems, Inc.
 1414 Massachusetts Ave.
 Boxborough, MA 01719
 EMail: tnadeau@cisco.com
 Cheenu Srinivasan
 Bloomberg L.P.
 731 Lexington Avenue
 New York, NY 10022
 Phone: (212) 617-3682
 EMail: cheenu@bloomberg.net
 Adrian Farrel
 Old Dog Consulting
 Phone: +44 (0) 1978 860944
 EMail: adrian@olddog.co.uk

Nadeau, et al. Informational [Page 31] RFC 4221 MPLS Management Overview November 2005

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Nadeau, et al. Informational [Page 32]

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