CISCO-VOA-MIB

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Organization: Cisco Systems, Inc.

Last Updated: 2002-05-07

Category: Optical and WDM, Vendor: Cisco Devices

Description: Manages Cisco Variable Optical Attenuator (VOA) hardware for optical power level adjustment in WDM networks.

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What Is CISCO-VOA-MIB?

The CISCO-VOA-MIB is a Cisco enterprise MIB for managing Variable Optical Attenuator (VOA) hardware modules used in Cisco's DWDM/optical transport platforms to equalize per-channel or per-band optical power before multiplexing wavelengths through an EDFA. It exposes hardware configuration objects (attenuation direction, control mode, desired power target) and status objects reflecting the current attenuation level and when it last changed. This is direct hardware-status monitoring of optical components: an administrator tracks the actual attenuation level against the desired power setpoint to confirm the VOA is correctly equalizing channel power, and the last-change timestamp helps correlate optical power anomalies with a specific configuration or control event. It is used alongside Cisco's broader optical-transport and ENTITY-MIB inventory MIBs that identify the physical VOA module and its containing chassis/slot. It is deployed in Cisco DWDM optical transport network elements, such as ONS/NCS platforms, used by carriers for wavelength-division-multiplexed fiber networks. Engineers can download the CISCO-VOA-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in CISCO-VOA-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

Cisco DWDM optical transport platforms (ONS/NCS series)

Monitoring Examples

An administrator would poll cVoaTable/cVoaEntry to compare cVoaAttenuation against cVoaDesiredPower for a given channel, confirming the attenuator is holding the target power level, and check cVoaAttenuationControlMode to see whether the VOA is under automatic or manual control. A cVoaAttenuationLastChange timestamp that changes unexpectedly would prompt investigation into what triggered a re-equalization, such as a wavelength being added or removed from the multiplexed signal.

What Can Be Monitored

VOA attenuation level
desired power setpoint
attenuation control mode
attenuation last-change time
VOA direction

Imported Objects

From CISCO-OPTICAL-MONITOR-MIB

OpticalIfDirection

From CISCO-SMI

ciscoMgmt

OBJECT-IDENTITY

From IF-MIB

ifIndex

OBJECT-TYPE

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Integer32
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

TEXTUAL-CONVENTION
TimeStamp

OIDs

OID symbolic	OID numeric	Type	Access	Description
ciscoVoaMIB	1.3.6.1.4.1.9.9.262			This MIB module defines objects to configure and manage the Variable Optical Attenuator (VOA) modules. VOA modules are typically used to attenuate channels added by a network element, in order to equalize the input power of each wavelength before the multiplexed signal consisting of all wavelengths is sent through an EDFA. There may be a separate VOA per channel, one VOA per band of wavelengths, or one VOA for the pass through wavelengths. VOA modules are also often used before terminating optical wavelengths at optical receivers, in order to avoid receiver saturation. The VOAs may be present on various modules within the network element, for example, on an Optical Add/Drop Multiplexer (OADM) module, on the same module as an optical transceiver, or on a separate module of its own.
cVoaMIBObjects	1.3.6.1.4.1.9.9.262.1
cVoaBaseGroup	1.3.6.1.4.1.9.9.262.1.1
cVoaTable	1.3.6.1.4.1.9.9.262.1.1.1		not-accessible	This table provides objects to configure and control the attenuation on VOAs.
cVoaEntry	1.3.6.1.4.1.9.9.262.1.1.1.1		not-accessible	An entry in the cVoaTable provides objects to configure and control the attenuation level of a VOA at an interface, for a given direction.
OPT cVoaDirection	1.3.6.1.4.1.9.9.262.1.1.1.1.1	OpticalIfDirection	not-accessible	This is the second index into the cVoaTable and indicates the direction for which the attenuation level at this interface is being controlled, in this entry.
INT cVoaAttenuationControlMode	1.3.6.1.4.1.9.9.262.1.1.1.1.2	INTEGER	read-write	This object is used to set the mode of controlling the attenuation level of a VOA at an interface. When the mode is set to 'manual', the attenuation level is configured manually, by setting the desired attenuation level in the cVoaAttenuation object. The cVoaDesiredPower object does not apply in this case. When the mode is set to 'automatic', the attenuation level is continuously adjusted to maintain a desired power level, after attenuation. The desired optical power level after attenuation is configured using the cVoaDesiredPower object. The cVoaAttenuation object cannot be configured in this case, but it indicates the attenuation level derived from the desired power level. The automatic mode of controlling attenuation should not be used when the monitored power level includes multiple wavelengths, since the power level monitor cannot distinguish between a decrease in power across all wavelengths, versus a loss of power of some but not all wavelengths. If some but not all wavelengths go down, this would cause the attenuation level to be automatically decreased, leading to an increase in the power level of the remaining wavelengths.
OPT cVoaAttenuation	1.3.6.1.4.1.9.9.262.1.1.1.1.3	OpticalAttenInDb	read-write	This object indicates the attenuation level applied at the interface. When the cVoaAttenuationControlMode object is set to 'manual', the attenuation level may be specified by setting this object.
TIM cVoaAttenuationLastChange	1.3.6.1.4.1.9.9.262.1.1.1.1.4	TimeStamp	read-only	This object indicates the value of sysUpTime at the last time the attenuation level was adjusted at this interface, in the given direction.
OPT cVoaDesiredPower	1.3.6.1.4.1.9.9.262.1.1.1.1.5	OpticalPowerInDbm	read-write	This object indicates the desired optical power level, after attenuation, at the interface. This object applies only when the cVoaAttenuationControlMode object is set to 'automatic'. In this mode, the attenuation level is continuously adjusted to maintain the desired power level, after attenuation, as specified by this object.
cVoaMIBConformance	1.3.6.1.4.1.9.9.262.3
cVoaMIBCompliances	1.3.6.1.4.1.9.9.262.3.1
cVoaMIBCompliance	1.3.6.1.4.1.9.9.262.3.1.1			The compliance statement for platforms that provide configuration and control of VOA modules.
cVoaMIBGroups	1.3.6.1.4.1.9.9.262.3.2
cVoaMIBBaseGroup	1.3.6.1.4.1.9.9.262.3.2.1			A collection of mandatory managed objects that provide basic configuration and control of the VOA modules.

RFC description

Variable Optical Attenuator (VOA) module management for optical networks. Controls optical signal attenuation on wavelengths before EDFA amplification or optical receiver termination.

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Download CISCO-VOA-MIB

What Is CISCO-VOA-MIB?

Supported Devices

Monitoring Examples

What Can Be Monitored

This MIB depends on

Related MIBs

RFC description