GDCCMN-MIB

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Category: Textual Conventions and Registries, Vendor: GDC

Description: General DataComm common MIB providing shared textual conventions and base objects for GDC product MIBs.

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What Is GDCCMN-MIB?

GDCCMN-MIB is a General DataComm (GDC) common MIB module providing shared textual conventions and base alarm-management objects reused across GDC's family of telecom/datacom product-specific MIBs. It centers on a generic alarm status and alarm masking framework, with tables tracking current alarm status and per-alarm enable/mask settings. This makes it directly relevant to monitoring hardware status — the alarm status table reports live fault conditions on the device, while the mask table controls which alarms are actively reported, and a trap object notifies management stations of alarm-state changes. Because object names in this legacy module are sparsely documented, engineers often rely on a GDCCMN-MIB MIB Browser session to enumerate the alarm status and mask tables directly, given that as a shared "common" module it is depended upon by other GDC product-specific MIBs that extend its alarm framework rather than duplicating it. It is typically deployed on General DataComm telecom access and transmission equipment (e.g. modems, muxes, network access devices) in carrier and enterprise networks.

IPNetwork Monitor allows you to monitor SNMP objects defined in GDCCMN-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

General DataComm (GDC) telecom access/transmission equipment
modems and multiplexers

Monitoring Examples

An admin polling cmnAlarmStatusTable/cmnAlarmStatusEntry indexed by cmnAlarmStatusIndex can read cmnAlarmCurrentStatus for each cmnAlarmStatusIdentifier to see which alarms are currently active on the device. Cross-referencing cmnAlarmMaskTable/cmnAlarmMaskEntry (cmnAlarmMask keyed by cmnAlarmMaskIndex) confirms whether a given alarm is enabled for trap notification, explaining why an active fault may not have generated a cmnTrap. cmnMIBVersion and cmnCommName help identify the specific module/firmware baseline in use.

What Can Be Monitored

active alarm status per alarm point
alarm mask/enable configuration
alarm trap notifications
MIB/firmware version identification

Imported Objects

From RFC-1212

OBJECT-TYPE

From RFC-1215

TRAP-TYPE

From RFC1155-SMI

IpAddress
enterprises

From RFC1213-MIB

DisplayString

OIDs

OID symbolic	OID numeric	Type	Access	Description
cmn	1.3.6.1.4.1.498.1
cmnAlarm	1.3.6.1.4.1.498.1.4
INT cmnAlarmCurrentStatus	1.3.6.1.4.1.498.1.4.1.1.3	INTEGER	read-only	The current status of the alarm. The value inactive(1) indicates that this alarm is currently inactive. The value active(2) indicates that this alarm is currently active.
INT cmnAlarmMask	1.3.6.1.4.1.498.1.4.2.1.3	INTEGER	read-write	The alarm masking control. When the value is mask(1), then the alarm is masked and will not be reported. When the value is unmask(2), then the alarm will be reported depending on the threshold configuration.
cmnAlarmMaskEntry	1.3.6.1.4.1.498.1.4.2.1		not-accessible	An entry in the alarm mask table.
OID cmnAlarmMaskIdentifier	1.3.6.1.4.1.498.1.4.2.1.2	OBJECT IDENTIFIER	read-only	The unique alarm identifier assigned to this alarm type. The format of this identifier is an OBJECT IDENTIFIER that has the following format: {iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) gdc(498) xxx(x) alarm(z) yyy(y) where xxx(x) is the administratively assigned family object identifier (z) is the object identifier for alarms in the family defined MIB and yyy(y) is the administratively assigned alarm type identifier for this alarm.
INT cmnAlarmMaskIndex	1.3.6.1.4.1.498.1.4.2.1.1	INTEGER	read-only	The index value which uniquely identifies the interface to which this entry is applicable.
cmnAlarmMaskTable	1.3.6.1.4.1.498.1.4.2		not-accessible	The cmnAlarmMaskTable contains entries that report the current masking state of alarms. The mask of an alarm can be changed between masked(1) and unmasked(2). If an alarm is unmasked, the threshold configuration can affect the reporting of this alarm. The structure of the table is such that alarm mask is supported on a unit or interface basis, and then on an alarm type basis within the interface. For simplicity sake and to support the reporting of status of all alarms, a unit is treated as an interface in this table.
cmnAlarmStatusEntry	1.3.6.1.4.1.498.1.4.1.1		not-accessible	An entry in the Alarm Status table.
OID cmnAlarmStatusIdentifier	1.3.6.1.4.1.498.1.4.1.1.2	OBJECT IDENTIFIER	read-only	The unique alarm identifier assigned to this alarm type. The format of this identifier is an OBJECT IDENTIFIER that has the following format: {iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) gdc(498) xxx(x) alarm(z) yyy(y) where xxx(x) is the administratively assigned family object identifier (z) is the object identifier for alarms in the family defined MIB and yyy(y) is the administratively assigned alarm type identifier for this alarm.
INT cmnAlarmStatusIndex	1.3.6.1.4.1.498.1.4.1.1.1	INTEGER	read-only	The index value which uniquely identifies the interface to which this entry is applicable.
cmnAlarmStatusTable	1.3.6.1.4.1.498.1.4.1		not-accessible	The cmnAlarmStatusTable contains entries that report the status of alarms. The status of an alarm indicates whether the alarm is currently active or inactive. This information will be determined by the network element depending on the alarm threshold configuration. The structure of the table is such that alarm status is supported on a unit or interface basis, and then on an alarm type basis within the interface. For simplicity sake and to support the reporting of status of all alarms, a unit is treated as an interface in this table.
NTF cmnAlarmStatusTrap	1.3.6.1.4.1.498.1.4.0.1			The alarm status trap. This trap is set whenever an alarm status change occurs to report an alarm. The variable bindings contain the status for each alarm that changes state. Note that the OBJECT IDENTIFIER of the variable contains the interface, family type, and alarm type of the alarm encoded within. More than one alarm can be sent in the trap, if the network element indicates that more than one has changed at the same time.
cmnCommName	1.3.6.1.4.1.498.1.2
INT cmnCommunityAccess	1.3.6.1.4.1.498.1.2.2.1.3	INTEGER	read-write	The Access associated with the community name. When a new row is created by adding a new name, the default value will be noAccess(3).
cmnCommunityEntry	1.3.6.1.4.1.498.1.2.2.1		not-accessible	Information needed to deliver traps to a particular management station.
INT cmnCommunityIndex	1.3.6.1.4.1.498.1.2.2.1.1	INTEGER	read-only	The index number associated with the entry in the community name table. The range cannot be specified on the SYNTAX line since it will vary from agent to agent. The range will be 1 to the number specified by cmnCommunityNumber.
STR cmnCommunityName	1.3.6.1.4.1.498.1.2.2.1.2	DisplayString	read-write	The community name being defined.
INT cmnCommunityNumber	1.3.6.1.4.1.498.1.2.1	INTEGER	read-only	The maximum number of entries the Community table can hold.
INT cmnCommunityStatus	1.3.6.1.4.1.498.1.2.2.1.4	INTEGER	read-write	The status of the entry. If read and the entry exists, valid(1) will always be returned. Invalid entries will be removed from the table.
cmnCommunityTable	1.3.6.1.4.1.498.1.2.2		not-accessible	A table of Community Names and there defined access. To add an entry to the table, a set on the Community Name for the instance (Index) needs to be performed. To delete an entry, a set on the Status to invalid on the instance needs to be performed.
STR cmnMIBVersion	1.3.6.1.4.1.498.1.3	DisplayString	read-only	The version number of the MIB, to allow products to know which MIB is being supported. The version number will be x.yzT where x is a major revision (1-9), y is a minor revision(0-9), z is a typo revision (0-9) and T indicates the MIB is still a test revision(A-Z). When a release is complete no T should exist.
cmnTrap	1.3.6.1.4.1.498.1.1
STR cmnTrapAddrCommunity	1.3.6.1.4.1.498.1.1.3.1.3	DisplayString	read-write	The community name expected by the management station receiving traps.
cmnTrapAddrEntry	1.3.6.1.4.1.498.1.1.3.1		not-accessible	Information needed to deliver traps to a particular management station.
IP cmnTrapAddrIpDest	1.3.6.1.4.1.498.1.1.3.1.1	IpAddress	read-only	The IP address of the management agent receiving traps. The IP address of 0.0.0.0 will not be allowed.
INT cmnTrapAddrNumber	1.3.6.1.4.1.498.1.1.2	INTEGER	read-only	The maximum number of entries the TRAP table can hold.
INT cmnTrapAddrStatus	1.3.6.1.4.1.498.1.1.3.1.4	INTEGER	read-write	The status of the entry. If read and the entry exists, valid(1) will always be returned. Invalid entries will be removed from the table.
cmnTrapAddrTable	1.3.6.1.4.1.498.1.1.3		not-accessible	A table of management systems ready to accept traps generated by this node. To add an entry to the table, a set on the Community name for the instance (IP Address and UDP PORT) needs to be performed. To delete an entry, a set on the Status to invalid on the instance needs to be performed.
INT cmnTrapAddrUdpDest	1.3.6.1.4.1.498.1.1.3.1.2	INTEGER	read-only	The UDP port number used by the management station to receive traps. A value of 0 for the UDP port number will not be allowed.
INT cmnTrapGlobal	1.3.6.1.4.1.498.1.1.1	INTEGER	read-write	This globally enables and disables all TRAPs from an agent. All variables should provide a means to mask a TRAP and to provide some threshold before a TRAP is sent.
gdc	1.3.6.1.4.1.498

FAQ

How can GDCCMN-MIB be used to keep an eye on fault conditions across a fleet of General DataComm modems and multiplexers?
GDCCMN-MIB is the shared 'common' module that GDC's product-specific MIBs build on, and it centers on a generic alarm framework: a table reporting the current alarm status per alarm point on the device, a companion table showing which alarms are enabled or masked, and a trap object that fires when an alarm state changes. In a network operations context, you'd poll the alarm status table across your GDC access and transmission devices (or watch for the trap) to catch fault conditions in near real time, while using the mask table to confirm which alarms are actually being reported versus suppressed on each unit.

Why would an engineer open a MIB browser against GDCCMN-MIB instead of just reading documentation?
Because GDCCMN-MIB is a legacy module with sparsely documented object names, engineers commonly walk the alarm status and alarm mask tables directly in a MIB browser to figure out what's actually there, rather than relying on written specs. Since it's a shared base module that other GDC product MIBs extend rather than duplicate, understanding its alarm tables first also clarifies what functionality any given GDC device's specific MIB is inheriting.

RFC description

General DataComm (GDC) common MIB module defining SNMP management objects for GDC networking equipment.

Start monitoring General DataComm (GDC) telecom access/transmission equipment (shared alarm framework) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download GDCCMN-MIB

What Is GDCCMN-MIB?

Supported Devices

Monitoring Examples

What Can Be Monitored

This MIB depends on

Related MIBs

FAQ

RFC description