The benefits described in the following paragraphs are available to you with the MPLS-LSR-STD-MIB.

The MPLS-LSR-STD-MIB contains managed objects that support the retrieval of label switching information from a router. The MIB is based on RFC 3813. This implementation enables a network administrator to get information on the status, character, and performance of the following:

• MPLS-capable interfaces on the LSR
• Incoming MPLS segments (labels) at an LSR and their associated parameters
• Outgoing segments (labels) at an LSR and their associated parameters

In addition, the network administrator can retrieve the status of cross-connect table entries that associate MPLS segments with each other.

The figure below shows the association of the cross-connect table with incoming and outgoing segments (labels).

Figure 1. Label Forwarding with the Cross-Connect Table

Note	The out-segment table does not display “no label” entries. Labels that are displayed as “POP” are the special MPLS label 3.

The notation used in the MPLS-LSR-STD-MIB follows the conventions defined in Abstract System Notation One (ASN.1). ASN.1 defines an Open Systems Interconnection (OSI) language used to describe data types independently from particular computer structures and presentation techniques. Each object in the MIB incorporates a DESCRIPTION field that includes an explanation of the object’s meaning and usage, which, together with the other characteristics of the object (SYNTAX, MAX-ACCESS, and INDEX) provides sufficient information for management application development, as well as for documentation and testing.

The MPLS-LSR-STD-MIB represents an ASN.1 notation that represents an idealized MPLS LSR.

A network administrator can access the entries (objects) in the MPLS-LSR-STD-MIB by means of any SNMP-based network management system (NMS). The network administrator can retrieve information in the MPLS-LSR-STD-MIB using standard SNMP get and getnext commands.

Typically, SNMP runs as a low-priority process. The response time for the MPLS-LSR-STD-MIB is expected to be similar to that for other MIBs. The size and structure of the MIB and other MIBs in the system influence response time when you retrieve information from the management database. Traffic through the LSR also affects SNMP performance. The busier the switch is with forwarding activities, the greater the possibility of lower SNMP performance.

The top-level components of the MPLS-LSR-STD-MIB are:

• Tables and scalars (mplsLsrObjects)
• Notifications (mplsLsrNotifications)
• Conformance (mplsLsrConformance)

This section lists and briefly describes of the main and supplementary tables in the MPLS-LSR-STD-MIB.

The Cisco implementation of the MPLS-LSR-STD-MIB supports four main tables:

• MPLS interface table (mplsInterfaceTable)—Contains entries for all MPLS-capable interfaces on the LSR.
• MPLS in-segment table (mplsInSegmentTable)—Contains a description of incoming labels on the LSR.
• Mpls out-segment table (mplsOutSegmentTable)—Contains a description of outgoing labels on the LSR.
• MPLS cross-connect table (mplsXCTable)—Contains the connections between the in-segments and out-segments on the LSR. A single cross-connect entry is equivalent to a single entry in the Label Forwarding Information Base (LFIB), showing an in-label being switched to an out-label. A cross-connect entry can exist where no corresponding in-segment exists. For example, only the outgoing label exists at the head end of a traffic engineering (TE) tunnel.

Three tables manage labels, the MPLS in-segment table, the MPLS out-segment table, and the MPLS cross-connect tables.

The MIB contains three supplementary tables to supply performance information:

• MPLS interface performance table (mplsInterfacePerfTable)—Augments the MPLS interface table. Provides objects to measure performance for MPLS-capable interfaces on the LSR.
• MPLS in-segment performance table (mplsInSegmentPerfTable)—Augments the MPLS in-segment table. Provides performance information and counters for incoming segments on the LSR.
• MPLS out-segment performance table (mplsOutSegmentPerfTable)—Augments the MPLS out-segment table. Provides performance information and counters for outgoing segments on the LSR.

You can use SNMP getand getnextcommands to gather label switching information for an MPLS LSR available through the MPLS-LSR-STD-MIB tables. This section describes the MPLS LSR information available from each table:

The MPLS-LSR-STD-MIB supports several scalar objects. In the Cisco implementation of the MIB for Cisco IOS Releases 12.2(33)SRB and 12.2(33(SB), the following scalar objects are hard-coded to the value indicated and are read-only objects. This symbol (“ ”) indicates an empty string.

• mplsInSegmentIndexNext (“ ”)—The value for the in-segment index when the LSR creates an entry in the MPLS in-segment table. The “ ” indicates that this is not implemented because modifications to this table are not allowed.
• mplsOutSegmentIndexNext (“ ”)—The value for the out-segment index when an LSR creates a new entry in the MPLS out-segment table. The “ ” indicates that this is not implemented because modifications to this table are not allowed.
• mplsXCTIndexNext (“ ”)—The value for the cross-connect index when an LSR creates an entry in the MPLS cross-connect table. The “ ” indicates that no unassigned values are available.
• mplsMaxLabelStackDepth (6)—The value for the maximum stack depth.
• mplsLabelStackIndexNext (“ ”)—The value for the label stack index when an LSR creates entries in the MPLS label stack table. The “ ” indicates that no unassigned values are available.
• mplsXCNotificationEnable (false)—Cross-connect notifications are not sent when this value is false.

The following notifications are not supported:

• mplsXCUp
• mplsXCDown

In the MPLS cross-connect table, cross-connect entries associate incoming segments with outgoing segments. The following objects index the cross-connect entry:

• Cross-connect index (mplsXCIndex)—A unique identifier for a group of cross-connect entries in the cross-connect table.
• In-segment index (mplsXCInSegmentIndex)—The value of this object is the same value as for the mplsInSegmentIndex in the in-segment table.

The in-segment table (mplsInSegmentTable) is indexed by the incoming label. The mplsInSegmentIndex is a 4-byte octet string containing the local label.

• Out-segment index (mplsXCOutSegmentIndex)—The value of this object is the same value as for the mplsOutSegmentIndex in the out-segment table.

The following figure shows the relationship among the indexes of the mplsInSegmentTable, the mplsXCTable, and the mplsOutSegmentTable.

Figure 2. MPLS-LSR-STD-MIB Indexing

The mplsInSegmentIndex, mplsXCindex, and mplsOutSegmentIndex values are defined as an MplsIndexType, which is a variable-length octet string that can be used to specify an interface index, a physical card or device, or an application ID.

MPLS Cross-Connect Table Index

The mplsXCIndex is a variable-length octet string, the size of which depends on the application type that is represented and the amount of information needed to represent the label for that application type. The application type is based on a forwarding path identifier (FPI) type that is supported by the MFI. The Cisco implementation of the MPLS-LSR-STD-MIB for Cisco IOS Release xx.x(x)X supports the following FPI types: LABEL, TE, and IPV4.

The figure below shows how the MPLS-LSR-STD-MIB represents the application types for the cross-connect mplsXCIndex object.

Figure 3. MPLS-LSR-STD-MIB Application Type Representation for mplsXCIndex Object

The MPLS interface configuration table lists interfaces that support MPLS technology. An LSR creates an entry dynamically in this table for each MPLS-capable interface. An interface becomes MPLS-capable when MPLS is enabled on that interface. A nonzero index for an entry in this table points to the ifIndex for the corresponding interface entry in the MPLS-layer in the ifTable of the Interfaces Group MIB.

The ifTable contains information on each interface in the network. Its definition of an interface includes any sublayers of the internetwork layer of the interface. MPLS interfaces fit into this definition of an interface. Therefore, each MPLS-enabled interface is represented by an entry in the ifTable.

The interrelation of entries in the ifTable is defined by the interfaces stack group of the Interfaces Group MIB. The figure below shows how the stack table might appear for MPLS interfaces. The underlying layer refers to any interface that is defined for MPLS internetworking, for example, ATM, Frame Relay, or Ethernet.

Figure 4. Interface Group MIB Stack Table for MPLS Interfaces

Note	Tunnel interfaces are included in the MPLS list for the current implementation.

MIB structure is represented by a tree hierarchy. Branches along the tree have short text strings and integers to identify them. Text strings describe object names, and integers allow computer software to encode compact representations of the names.

The MPLS-LSR-STD-MIB falls on the branch of the Internet MIB hierarchy represented by the object identifier 1.3.6.1.2.1.10.166. This branch can also be represented by its object name iso.org.dod.internet.mgmt.mib-2.transmission.mplsStdMIB. The MPLS-LSR-STD-MIB is identified by the object name mplsLsrStdMIB, which is denoted by the number 2. Therefore, objects in the MPLS-LSR-MIB can be identified in either of the following ways:

• The object identifier—1.3.6.1.2.1.10.166.2.[MIB-variable]
• The object name— iso.org.dod.internet.mgmt.mib-2.transmission.mplsStdMIB.mplsLsrStdMIB.[MIB-variable]

To display a MIB-variable, you enter an SNMP get command with an object identifier. Object identifiers are defined by the MPLS-LSR-STD-MIB.

The figure below shows the position of the MPLS-LSR-STD-MIB in the Internet MIB hierarchy.

Figure 5. MPLS-LSR-STD-MIB in the Internet MIB Hierarchy

The MPLS LFIB is the component of the Cisco MPLS subsystem that contains management information for LSRs. You can access this management information by means of either of the following:

• Using the show mpls forwarding-table CLI command
• Entering SNMP get commands on a network manager

The following examples show how you can gather LSR management information using both methods.

Router# show mpls forwarding-table 
Local  Outgoing      Prefix            Bytes Label   Outgoing   Next Hop    
Label  Label or VC   or Tunnel Id      Switched      interface              
16     Pop Label     IPv4 VRF[V]       1000          aggregate/vpn1             
17     Pop Label     10.0.0.3/32       0             PO7/1/0    point2point 
18     Pop Label     10.30.1.0/16      0             PO7/1/0    point2point 
19     17            10.0.0.1/32       0             PO7/1/0    point2point 
20     No Label      10.9.0.0/16[V]    0             GE3/1      10.30.2.2    
21     No Label      10.0.0.7/32[V]    128856        GE3/1      10.30.2.2    

MPLS-LSR-STD-MIB Output

SNMP commands on MIB objects also allow you to display the label forwarding information for a specific MPLS LSR.

You can do a walk-through of the MIB by running a command such as getmany -v2c public mplsLsrStdMIB on a network manager where getmany does repeated SNMP getnext operations to retrieve the contents of the MPLS-LSR-STD-MIB. The figure below shows index information for the mplsXCOperStatus MPLS-LSR-STD-MIB object and how to read the information in the MIB output that follows.

Figure 6. Index Information for the mplsXCOperStatus MPLS-LSR-STD-MIB Object

mplsXCOperStatus.5.0.0.0.0.0.4.0.0.0.0.7.0.0.0.0.0.0.1 = up
mplsXCOperStatus.5.0.0.0.0.1.4.0.0.0.1.1.0 = up
mplsXCOperStatus.5.0.0.0.0.2.4.0.0.0.2.7.0.0.0.0.2.0.1 = up
mplsXCOperStatus.5.0.0.0.0.3.4.0.0.0.3.1.0 = up
mplsXCOperStatus.5.0.0.0.0.16.4.0.0.0.16.7.0.0.0.0.16.0.1 = up
mplsXCOperStatus.5.0.0.0.0.17.4.0.0.0.17.7.0.0.0.0.17.0.1 = up
mplsXCOperStatus.5.0.0.0.0.18.4.0.0.0.18.7.0.0.0.0.18.0.1 = up
mplsXCOperStatus.5.0.0.0.0.19.4.0.0.0.19.7.0.0.0.0.19.0.1 = up
mplsXCOperStatus.5.0.0.0.0.20.4.0.0.0.20.1.0 = up
mplsXCOperStatus.5.0.0.0.0.21.4.0.0.0.21.1.0 = up
mplsXCOperStatus.6.2.10.0.0.3.32.1.0.8.2.10.0.0.3.32.0.1 = up
mplsXCOperStatus.6.2.10.30.0.16.1.0.8.2.30.1.0.0.16.0.1 = up

You can continue to scan the output of the getmany command for the following MIB objects from the MPLS out-segment table:

• Out-segment’s top label objects (mplsOutSegmentTopLabel)

mplsOutSegmentTopLabel.7.0.0.0.0.0.0.1 = 3
mplsOutSegmentTopLabel.7.0.0.0.0.2.0.1 = 3
mplsOutSegmentTopLabel.7.0.0.0.0.16.0.1 = 3
mplsOutSegmentTopLabel.7.0.0.0.0.17.0.1 = 3
mplsOutSegmentTopLabel.7.0.0.0.0.18.0.1 = 3
mplsOutSegmentTopLabel.7.0.0.0.0.19.0.1 = 17
mplsOutSegmentTopLabel.8.2.10.0.0.1.32.0.1 = 17
mplsOutSegmentTopLabel.8.2.10.0.0.3.32.0.1 = 3
mplsOutSegmentTopLabel.8.2.10.30.0.16.0.1 = 3

• Out-segment’s interface (mplsOutSegmentIInterface)

mplsOutSegmentInterface.7.0.0.0.0.0.0.1 = 0
mplsOutSegmentInterface.7.0.0.0.0.2.0.1 = 0
mplsOutSegmentInterface.7.0.0.0.0.16.0.1 = 0
mplsOutSegmentInterface.7.0.0.0.0.17.0.1 = 55
mplsOutSegmentInterface.7.0.0.0.0.18.0.1 = 55
mplsOutSegmentInterface.7.0.0.0.0.19.0.1 = 55
mplsOutSegmentInterface.8.2.10.0.0.1.32.0.1 = 55
mplsOutSegmentInterface.8.2.10.0.0.3.32.0.1 = 55
mplsOutSegmentInterface.8.2.10.30.0.16.0.1 = 55

For more information on how to read the indexing for MPLS-LSR-STD-MIB objects, see the MPLS-LSR-STD-MIB Indexing—Linking Table Elements.

Cisco IOS Releases 12.2(33)SRB and 12.2(33)SB include the VPN Aware LSR MIB feature that enables the MPLS-LSR-STD-MIB to get VPN context information. This feature adds support for different contexts for different MPLS VPNs. Users of the MIB can display per-VPN entries in the MPLS-LSR-STD-MIB tables. The VPN Aware LSR MIB feature does not change the syntax of the MPLS-LSR-STD-MIB. It changes the number and types of entries within the tables.

The MPLS-LSR-STD-MIB can show information about only one context at a time. You can specify either a global context or an MPLS VPN context using an SMNP security name. The security name must match the SNMP community name when an SNMP request is performed on a MIB entry.

The MPLS-LSR-STD-MIB based on RFC 3813 provides the same basic functionality as the MPLS-LSR-MIB based on Version 05 of the IETF MPLS-LSR-MIB. They both provides an interface for managing label switching through the use of SNMP.

After the implementation of the MPLS-LSR-STD-MIB (RFC 3813) in Cisco IOS Releases 12.2(33)SRB and 12.2(33)SRB, the MPLS-LSR-MIB will exist for a period of time before support is completely removed. This gives you the chance to migrate to the MPLS-LSR-STD-MIB. Both MIBs can coexist in the same image because the MPLS-LSR-STD-MIB and the MPLS-LSR-MIB have different root object identifiers (OIDs).

The following sections contain information about the major differences between the MPLS-LSR-STD-MIB and the MPLS-LSR-MIB:

The MPLS-LSR-STD-MIB requires the following:

• SNMP installed and enabled on the LSR
• MPLS enabled on the LSR
• MFI

1.    enable


2.    show running-config


3.    configure terminal


4.    snmp-server community string [view view-name] [ro | rw] [ipv6 nacl] [access-list-number]


5.    end


6.    save running-config startup-config

Router> enable

Router# show running-config

Router# configure terminal

Router(config)# snmp-server community public ro

Router(config)# end

Router# save running-config startup-config

1.    telnet device-ip-address


2.    enable


3.    show running-config


4.    exit

Prompt> telnet 10.15.230.20

Router> enable
Router#

Router# show running-config
.
.
.
snmp-server community public RO

Router# exit
Router>

The following example shows how to enable an SNMP agent.

Router# configure terminal
Router(config)# snmp-server community

In the following example, SNMPv1 and SNMPv2C are enabled. The configuration permits any SNMP manager to access all objects with read-only permissions using the community string public.

Router(config)# snmp-server community public 
 

In the following example, read-only access is allowed for all objects to members of access list 4 that specify the comaccess community string. No other SNMP managers have access to any objects.

Router(config)# snmp-server community comaccess ro 4