IP Application Services

Document ID: 13502

Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Detect Change of Frame Relay PVC States
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Introduction

There are three possible permanent virtual connection (PVC) states:

• Invalid

• Active

• Inactive

This document explains how you can detect Frame Relay PVC state changes using Simple Network Management Protocol (SNMP).

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document applies to all devices that support the RFC 1315 MIB.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Detect Change of Frame Relay PVC States

Use the frDLCIStatusChange trap (from RFC 1315 MIB). This trap is generated whenever a PVC changes state.

.1.3.6.1.2.1.10.32.0.1 
frDLCIStatusChange OBJECT-TYPE 
        -- FROM RFC1315-MIB 
        TRAP 
        VARBINDS        { frCircuitIfIndex, frCircuitDlci, frCircuitState } 
        DESCRIPTION    "This trap indicates that the indicated Virtual Circuit has changed state.  
                        It has either been created or invalidated, or has toggled between the 
                        active and inactive states." 
::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) transmission(10) frame-relay(32) 
frame-relay#(0) 1 } cfrCircuitEntry(1) 3 }

You can also get the current state by polling the frCircuitState variable from RFC 1315 MIB. Keep in mind that in most service provider networks, Frame Relay Local Management Interface (LMI) is not end-to-end, and that the service provider's switch may not accurately report loss of a PVC.

.1.3.6.1.2.1.10.32.2.1.3 
frCircuitState OBJECT-TYPE 
        -- FROM RFC1315-MIB 
        SYNTAX          Integer { invalid(1), active(2), inactive(3) } 
        MAX-ACCESS      read-write 
        STATUS          Mandatory 
        DESCRIPTION    "Indicates whether the particular virtual  circuit is operational.  In the absence 
                        of a Data Link Connection Management Interface, virtual circuit entries (rows) 
                        may be created by setting virtual circuit state  to 'active',  or deleted by 
                        changing Circuit state to 'invalid'. Whether or not the row actually disappears  
                        is left  to the implementation, so this object may actually read as 'invalid' 
                        for some arbitrary length of time. It is also legal to set the state of a virtual 
                        circuit to 'inactive' to temporarily disable a given circuit." 
::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) transmission(10) frame-relay(32) frCircuitTable(2) 
frCircuitEntry(1) 3 }

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