UCD-DLMOD-MIB

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Organization: University of California, Davis

Last Updated: 2000-01-26

Category: Net-SNMP and Linux

Description: Defines managed objects for dynamic loadable MIB modules in the Net-SNMP agent, allowing modules to be loaded and unloaded at runtime.

IPNetwork Monitor uses several OIDs from this MIB in network discovery and polling the applicable devices. Start monitoring UCD-DLMOD-MIB with a free 30-day trial of IPNetwork Monitor.

What Is UCD-DLMOD-MIB?

UCD-DLMOD-MIB is a module associated with the open-source Net-SNMP agent (originally from the UCD-SNMP project) that defines managed objects for dynamically loading and unloading MIB modules into a running SNMP agent without restarting it. It exposes a table of loadable modules, each with a name, filesystem path, load status, and any error encountered during loading. This MIB is squarely about software status monitoring on the management agent itself: it lets an administrator confirm which optional MIB modules are currently loaded into the agent process, detect a module that failed to load (surfacing the reason via dlmodError), and manage module lifecycle (load/unload) via dlmodStatus. It has an inherent dependency on the Net-SNMP agent's internal module architecture rather than any external standard MIB. It is typically used on Linux/Unix hosts running the Net-SNMP (snmpd) agent, where administrators consult the UCD-DLMOD-MIB MIB reference to extend agent functionality by dynamically loading custom or additional MIB modules at runtime.

IPNetwork Monitor allows you to monitor SNMP objects defined in UCD-DLMOD-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

Net-SNMP (UCD-SNMP) agent host, typically Linux/Unix server

Monitoring Examples

An administrator would poll dlmodTable/dlmodEntry, checking dlmodName and dlmodPath to confirm a custom module like a monitoring extension is loaded from the expected shared-object path, and checking dlmodStatus to see if it is active. If dlmodError is non-empty for an entry, that reveals the module failed to load, e.g., due to a missing symbol or incompatible agent version, which the admin would need to fix before that module's objects become available. dlmodNextIndex is used when requesting the agent to allocate a new table row for loading an additional module.

What Can Be Monitored

loaded MIB module name and status
module file path
module load error condition
dynamic module load/unload control

Imported Objects

From SNMPv2-SMI

Integer32
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

DisplayString

From UCD-SNMP-MIB

ucdExperimental

OBJECT-IDENTITY

How to Use in IPNetwork Monitor

Example using dlmodStatus OID:

Select a Net-SNMP agent host as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type dlmodStatus into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. The current status of the loaded module. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is an INTEGER-type OID, Value bounds is the most useful condition here — trigger an alert if the value is anything other than 'loaded', since that indicates the condition this object reports has changed to one worth investigating. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
ucdDlmodMIB	1.3.6.1.4.1.2021.13.14			This file defines the MIB objects for dynamic loadable MIB modules.
I32 dlmodNextIndex	1.3.6.1.4.1.2021.13.14.1	Integer32	read-only	The index number of next appropiate unassigned entry in the dlmodTable.
dlmodTable	1.3.6.1.4.1.2021.13.14.2		not-accessible	A table of dlmodEntry.
dlmodEntry	1.3.6.1.4.1.2021.13.14.2.1		not-accessible	The parameters of dynamically loaded MIB module.
I32 dlmodIndex	1.3.6.1.4.1.2021.13.14.2.1.1	Integer32	not-accessible	An index that uniqely identifies an entry in the dlmodTable.
STR dlmodName	1.3.6.1.4.1.2021.13.14.2.1.2	DisplayString	read-write	The module name.
STR dlmodPath	1.3.6.1.4.1.2021.13.14.2.1.3	DisplayString	read-write	The path of the module executable file.
STR dlmodError	1.3.6.1.4.1.2021.13.14.2.1.4	DisplayString	read-only	The last error from dlmod_load_module.
INT dlmodStatusEx	1.3.6.1.4.1.2021.13.14.2.1.5	INTEGER	read-write	The current status of the loaded module.

RFC description

Defines MIB objects for dynamically loadable MIB modules in UCD-SNMP agents.

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Download UCD-DLMOD-MIB