SNMP Trap Support for the Virtual Switch Interface Master MIB

This feature module explains how to use the virtual switch interface (VSI) Master MIB to monitor and manage ATM switches that are connected to routers through the virtual switch interface.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for SNMP Trap Support for the VSI Master MIB

Memory Requirements

  • The VSI Master MIB requires 75K of space.

  • The runtime dynamic random-access memory (DRAM) is approximately 5K times the number of logical/slave interfaces the VSI controller manages.

Performance

The VSI cross-connect error messages can be invoked hundreds of times every second. To prevent a performance impact on the label switch controller (LSC), enable rate-limiting to control the amount of traffic that passes into or out of an interface.

Restrictions for SNMP Trap Support for the VSI Master MIB

The VSI Master MIB is for ATM-LSRs running Multiprotocol Label Switching (MPLS).

Information About SNMP Trap Support for the VSI Master MIB

VSI Master and Slave

The VSI master is a software module that resides on a router. The VSI master enables an application to control an ATM switch that is connected to the router. The VSI protocol runs between the VSI master and a VSI slave. The VSI master can communicate with more than one slave across a control interface that connects the router to the switch. Each master/slave connection is called a VSI session. The figure below illustrates VSI sessions between a VSI master and slaves.

Figure 1. VSI Master and VSI Slaves

VSI Components That You Can Monitor with the VSI Master MIB

The VSI Master MIB allows you to monitor the operation of the switch. It also displays the results of the operations. Specifically, the VSI Master MIB allows you to monitor:

  • Connections between the router and the controlled switch.

  • The status of the interfaces in the switch

  • Virtual circuits (VCs) that are maintained across the interfaces.

MIB Traps

The VSI Master MIB allows you to enable traps on the following components:

  • Controllers--When VSI controllers are added or deleted

  • VSI sessions--When VSI sessions are established or disconnected

  • Logical interfaces--When logical interfaces become active or fail.

  • Cross-connects--When a cross-connect cannot be established.

  • Virtual circuits--When cross-connect resource thresholds are below configured thresholds.

MIB Objects

The following is a partial list of the supported MIB objects.

Controllers

You can obtain the following information about the controller:

  • Controller identifier

  • Number of cross-connects maintained in the switch

  • Protocol version

  • Controller interface index

  • Slave interface identifiers

  • Controller IP address

Sessions

You can obtain the following information about the VSI sessions:

  • Virtual path identifiers (VPIs) for session connections

  • Virtual circuit identifiers (VCIs) for the sessions

  • Switch identifier

  • Switch name

  • Session state

  • Protocol session monitoring

Logical Interfaces

Logical interfaces represent external interfaces that are available for connections. When you pair two external interfaces (represented by two logical interfaces), they provide a physical path through the switch. These physical paths support cross-connects. You can gather the following information about each logical interface:

  • Interface name

  • Operational state

  • Administrative state

  • Operational statistics

  • Cross-connect usage

  • Cross-connect availability

  • Cross-connect capacity

  • Interface capabilities

  • VC ranges

  • Interface index

  • IP address

Cross-Connects

Cross-connects are virtual links across two interfaces. The participating interfaces that support these links are listed in the MIB’s vsiLogicalIfTable entries. You can gather the following information about the cross-connects:

  • Interface associations

  • State

  • Identifiers

  • VPI/VCI identifiers for supporting interfaces

How to Configure SNMP Trap Support for the VSI Master MIB

Enabling the SNMP Agent

The SNMP agent for the VSI Master MIB is disabled by default. To enable the SNMP agent, perform the steps in this section.

SUMMARY STEPS

    1.    enable

    2.    show running-configuration

    3.    configure terminal

    4.    snmp-server community string RO

    5.    exit

    6.    write memory


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 show running-configuration


    Example:
    Router# show running-configuration
     

    Displays the running configuration to see if the SNMP agent is already running.

    If no SNMP information is present, continue with the steps below. If any SNMP commands are listed, you can modify them or leave them as they are.

     
    Step 3 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 4 snmp-server community string RO

    Example:
    router(config)# snmp-server community string RO
     

    Enables the read-only community string, where string is the read-only community string.

     
    Step 5 exit


    Example:
    router(config)# exit
     

    Exits the configuration mode and returns to the main prompt.

     
    Step 6 write memory

    Example:
    router# write memory
     

    Writes the modified configuration to nonvolatile memory (NVRAM) so that the settings stay permanently.

     

    Verifying That the SNMP Agent Has Been Enabled

    To verify that the SNMP agent has been enabled, perform the steps in this section.

    SUMMARY STEPS

      1.    enable

      2.    show running-configuration


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Router> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 show running-configuration


      Example:
      Router# show running-configuration
       

      Displays the running configuration to see if the SNMP agent is already running.

      If you see any "snmp-server" statements, SNMP has been enabled on the router.

       

      Enabling Traps

      SNMP notifications can be sent as traps or inform requests. A trap is an unsolicited message sent by an SNMP agent to an SNMP manager, indicating that some event has occurred. You can enable SNMP traps for the VSI Master MIB through the command line interface (CLI) or through an SNMP MIB object. The following sections explain these options.

      Enabling the VSI Master MIB Traps by Using Commands

      To enable SNMP traps, use the snmp-server enable traps command. An SNMP agent can be configured to send traps when one of the VSI Master MIB objects changes.

      The table below lists the CLI commands for enabling traps of specific VSI components.

      Table 1 CLI Commands that Control the Type of Traps You Receive

      To Receive Traps About

      Use This Command

      All components

      snmp server enable traps vsimaster

      Controllers being added or deleted

      snmp server enable traps vsimaster controller

      Sessions that connect or disconnect

      snmp server enable traps vsimaster session

      Logical interfaces that connect or disconnect

      snmp server enable traps vsimaster logical-interface

      Cross-connects that fail

      snmp server enable traps vsimaster cross-connect

      To enable VSI Master MIB traps to be sent from the agent to the manager, perform the following tasks in global configuration mode:

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    snmp-server enable traps vsimaster

        4.    snmp-server host hostname community-string vsimaster

        5.    exit


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 configure terminal


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 snmp-server enable traps vsimaster


        Example:
        router(config)# snmp-server enable traps vsimaster
         

        Enables the router to send VSI Master MIB traps.

         
        Step 4 snmp-server host hostname community-string vsimaster


        Example:
        router(config)# snmp-server host cisco.com restricted vsimaster
         

        Specifies the recipient of the trap message

         
        Step 5 exit


        Example:
        router(config)# exit
         

        Exits the configuration mode and returns to the main prompt.

         

        Enabling the VSI Master MIB Traps by Using SNMP MIB Objects

        You can also use MIB objects to specify which VSI components should send traps. To enable all VSI Master traps, use the vsiVSITrapEnable MIB object.

        Controller Traps

        To enable traps about the status of the controller, use the vsiControllerTrapEnable MIB object. The table below lists the MIB objects that are specific to the controller.

        Table 2 Controller Traps

        To Receive Traps When

        Use This MIB Object

        A controller is added

        vsiControllerAdded

        A controller is deleted

        vsiControllerDeleted

        VSI Session Traps

        To enable traps about the status of the VSI sessions, use the vsiSessionTrapEnable MIB object. The table below lists the MIB objects that are specific to the VSI sessions.

        Table 3 VSI Session Traps

        To Receive Traps When

        Use This MIB Object

        A VSI session is established

        vsiSessionUp

        A VSI session is disconnected

        vsiSessionDown

        Logical Interfaces

        To enable traps about the status of the logical interfaces, use the vsiLogicalIfTrapEnable MIB object. The table below lists the MIB objects that are specific to the logical interfaces.

        Table 4 Logical Interface Traps

        To Receive Traps When

        Use This MIB Object

        A logical interface is active

        vsiLogicalIfUp

        A logical interface fails

        vsiLogicalIfDown

        Cross-Connects

        To enable traps about the status of the cross-connects, use the vsiXCTrapEnable MIB object. The table below lists the MIB objects that are specific to the cross-connects.

        Table 5 Cross-Connect Traps

        To Receive Traps When

        Use This MIB Object

        A cross-connect cannot be established

        vsiXCFailed

        The LCN resources drop, possibly causing resource exhaustion.

        vsiLcnExhaustionNotice

        Setting Thresholds for Cross-Connects

        When cross-connects on XtagATM interfaces are created or deleted, a counter keeps a tally of the available logical channel number (LCN) resources. If the LCN resources become too low, the MIB sends messages to alert you of the possibility of resource exhaustion.

        You must first set the warning and alarm thresholds for the number of LCNs. To set the warning threshold, use the vsiAvailableChnlWarnThreshold MIB object. To set the alarm threshold, use the vsiAvailableChnlAlarmThreshold MIB object. The following list explains the usage guidelines of these MIB objects:

        • The threshold range is 1 to 100.

        • The warning threshold value must be greater than or equal to the value of the alarm threshold. Likewise, the alarm threshold value must be less than or equal to the value of the warning threshold.

        • If you only set one threshold, the MIB automatically sets the other threshold value to the same value as the threshold value you set.

        • By default, the threshold functionality is disabled.

        The following list explains the conditions under which warnings, alarms, and other messages are sent. The figure below illustrates the thresholds.

        • If the number of LCNs falls below the the warning threshold, a warning is sent. This message indicates that the potential for resource exhaustion is possible.

        • If the number of LCNs falls below the alarm threshold, an alarm is generated. This message indicates that the potential for resource exhaustion is imminent. If resource exhaustion occurs, cross-connects cannot be set up.

        • If the number of LCNs returns to above the warning threshold, a recovery message is generated. This message means that the potential for resource exhaustion no longer exists.

        • If the number of LCNs never crosses any threshold during the polling period, a normal message is generated.

        To prevent an overwhelming number of warnings or alarms from being generated during a sampling period, only one warning or alarm is generated when the number of LCNs falls below the threshold. The number of LCNs must return to normal before another warning or alarm is generated.

        Figure 2. Warning and Alarm Thresholds


        Note

        If XtagATM interfaces share resources, the LCN does not represent the actual amount of available resources. For example, the interfaces XtagATM1 and XtagATM2 share resources. If a cross-connect is set up on XtagATM1 but not on XtagATM2, XtagATM1 takes resources away from XtagATM2. When the VSI slave reports the available resources, it only reports on the resources for XtagATM1. The resources for XtagATM2 are not reported. This is because the VSI slave provides updates only when a cross-connect is set up or torn down or when the slave’s resources are partitioned. Any interfaces that are not set up or torn down do not send updates. As a result, if XtagATM2 doesn’t have enough resources in the resource pool, the problem does not get reported.

        Configuration Examples for SNMP Trap Support for the VSI Master MIB

        Enabling the SNMP Agent Example

        In the following example, the SNMP agent is enabled.

        snmp-server community

        Enabling the SNMP Agent with a Community String Example

        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. 

        snmp-server community public

        Enabling the SNMP Agent with Read-Only Access to Access List Members Example

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

        snmp-server community comaccess ro 4

        Enabling Traps and Specifying the Trap Recipient Example

        In the following example VSI Master MIB traps are sent to the host cisco.com. The community string is restricted. The first line enables the router to send VSI Master MIB traps in addition to any traps previously enabled. The second line specifies the destination of these traps and overwrites any previous snmp-server host commands for the host cisco.com.

        snmp-server enable traps vsimaster
snmp-server host cisco.com restricted vsimaster

        Additional References for ATM Multilink PPP Support on Multiple VCs

        The following sections provide references related to the ATM Multilink PPP Support on Multiple VCs feature.

        Related Documents

        Related Topic

        Document Title

        QoS configuration tasks

        Cisco IOS Quality of Service Solutions Configuration Guide

        QoS commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

        Cisco IOS Quality of Service Solutions Command Reference

        WAN configuration tasks

        Cisco IOS Wide-Area Networking Configuration Guide

        WAN commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

        Cisco IOS Wide-Area Networking Command Reference

        Cisco IOS commands

        Cisco IOS Master Commands List, All Releases

        MIBs

        MIB

        MIBs Link

        None

        To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

        http:/​/​www.cisco.com/​go/​mibs

        RFCs

        RFC

        Title

        RFC 1990

        The PPP Multilink Protocol (MP)

        Technical Assistance

        Description

        Link

        The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

        To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

        Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

        http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

        Feature Information for SNMP Trap Support for the VSI Master MIB

        The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

        Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
        Table 6 Feature Information for SNMP Trap Support for the Virtual Switch Interface Master MIB

        Feature Name

        Releases

        Feature Information

        SNMP Trap Support for the Virtual Switch Interface Master MIB

        12.2(2)T, 12.4(20)T

        This feature module explains how to use the virtual switch interface (VSI) Master MIB to monitor and manage ATM switches that are connected to routers through the virtual switch interface.

        The following commands were introduced or modifief: snmp-server community, snmp-server enable traps, snmp-server host.

        Support was removed for this feature in Cisco IOS Release 12.4(20)T and later releases.

        Glossary

        cloning --Creating and configuring a virtual-access interface by applying a specific virtual template interface. The template is the source of the generic user information and router-dependent information. The result of cloning is a virtual-access interface configured with all the commands in the template.

        LCP --Link control protocol. Protocol that establishes, configures, and tests data-link connections for use by PPP.

        NAS --Network access server. A device providing local network access to users across a remote access network such as the Public Switched Telephone Network (PSTN).

        PPP --Point-to-Point Protocol. A protocol that encapsulates network layer protocol information over point-to-point links. PPP is defined in RFC 1661.

        PPPoA --PPP over ATM.

        PPPoE --PPP over Ethernet.

        precloning --Cloning a specified number of virtual-access interfaces from a virtual template at system startup or when the command is configured.

        PVC --Permanent virtual circuit (or connection). Virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and teardown in situations where certain virtual circuits must exist all the time. In ATM terminology, called a permanent virtual connection.

        VC --Virtual channel. Logical circuit created to ensure reliable communication between two network devices. A VC is defined by a VPI/VCI pair and can be either permanent (PVC) or switched (SVC).

        virtual-access interface --Instance of a unique virtual interface that is created dynamically and exists temporarily. Virtual-access interfaces can be created and configured differently by different applications, such as virtual profiles and virtual private dialup networks. Virtual-access interfaces are cloned from virtual template interfaces.

        virtual template interface --A logical interface configured with generic configuration information for a specific purpose or configuration common to specific users, plus router-dependent information. The template takes the form of a list of Cisco IOS interface commands that are applied to virtual-access interfaces, as needed.

        VPDN --virtual private dial-up network. A system that permits dial-in networks to exist remotely from home networks, while giving the appearance of being directly connected.