SNMP

This Data Transfer/Device Plugin allows LinkServer to communicate with devices supporting Simple Network Management Protocol (SNMP). These devices may be connected to the system and, like with all other types of devices, their data is converted into unified form to allow accessing them from different AggreGate facilities. See Devices article for more information about the "normalized" representation of devices in Tibbo AggreGate.

LinkServer can communicate with devices using all versions of SNMP protocol (v1, v2 and v3). It supports secure communications introduced in SNMP v3.

Connecting SNMP Devices

New SNMP device is connected to the system using Add New Device action of Devices Context. First, you have to specify unique device name and select device type (SNMP):

ls_snmp_add

Click OK to register new device. At this point, new Device Context representing this device in the system will be created. Here is how it looks like in System Tree of AggreGate Client:

ls_snmp_node

Now you will be prompted to specify connection properties. In most cases is it necessary to enter IP Address or Host Name of the device. Click OK to finish registration.

Connection Settings

Connection settings define how LinkServer communicates with a certain SNMP device. These settings may be accessed using Edit Connection Properties action of Device Context. Here is a list of available connection properties:

Setting

Description

Protocol

Communication protocol (UDP or TCP).

IP Address of Host Name

Address of SNMP Agent.

Port

Port number on SNMP Agent.

SNMP Protocol Version

Version of SNMP protocol to use.

SNMP Community

Name of SNMP Community to use during device operations. Commonly used names are public and private.

Command Retries

Number of retries to be send before SNMP command fails.

Command Timeout (seconds)

Timeout of SNMP command.

Synchronization Period (seconds)

Period of synchronization between LinkServer and SNMP device (interval between synchronizations).

Maximum PDU size (bytes)

Maximum size of Protocol Data Unit (PDU) sent by LinkServer. Commonly used values are 484 (should be supported by any SNMP device) and 1472 (supported by most devices).

Execute SNMP Walk during each synchronization

Causes LinkServer to re-read information about SNMP device objects (settings) in the beginning of every synchronization procedure. See Synchronization section for details.

Security Level

There are three available security levels:

•	Authentication disabled, privacy (encryption) disabled

•	Authentication enabled, privacy (encryption) disabled

•	Authentication enabled, privacy (encryption) enabled

User Name

User name for SNMP authentication and privacy (encryption).

Authentication Protocol

MD5-based authentication or SHA-based authentication.

Authentication Passphrase

Password for authentication.

Privacy (Encryption) Protocol

DES-based encryption or AES-based encryption.

Privacy (Encryption) Passphrase

Password for encryption.

Synchronization

SNMP devices are synchronized with LinkServer like any other Devices. Synchronization between LinkServer and SNMP device includes the following steps:

•	Execute SNMP Walk operation, to discover available device settings (SNMP Objects). This step is performed only during the first synchronization for this SNMP device of if Execute SNMP Walk during each synchronization setting is enabled.

•	Find MIB Files Directory entries matching device settings, to get more information about each setting (setting type, description etc.).

•	Convert SNMP device settings into LinkServer Context Variables and create a Settings Cache.

•	Read SNMP device settings and storing these values in settings cache.

Global Configuration

Global configuration of SNMP plugin has two settings:

•	Receive SNMP traps setting

•	MIB Files Directory tabular setting

Receive SNMP Traps

When enabled, LinkServer receives SNMP traps and generates trap events. See SNMP Traps for details.

MIB FILES Directory

MIB (Management Information Base) files contain detailed information about objects provided by SNMP devices. MIB Files Directory table allows to manage MIB files that are used by SNMP plugin to get information about SNMP device settings and traps. This table has three fields:

Field

Description

Description of a MIB file.

MIB File

MIB file data.

Variable Descriptions

Defines how descriptions of device settings are formed. There are three choices:

•	By MIB symbol name (default)

•	By first sentence of MIB symbol description (sentences are assumed to be delimited by dots)

•	By first line of MIB symbol description

Correct value of this setting depends on the structure of MIB file and may be different for MIB files of different hardware manufacturers. The default value of this setting shows names of MIB symbols in variable descriptions, but it's always possible to see the full symbol descriptions by checking variable help (detailed description). This help is usually shown in tooltips in LinkServer User Interfaces. Here is an example screenshot from AggreGate Client:

ls_snmp_variable_help

Built-In MIB Files

There are more than one hundred of MIB files that are built into SNMP plugin and bundled with LinkServer distribution. They contain information about MIB objects of frequently monitored SNMP devices, such as routers, servers, network printers etc.

SNMP Traps

SNMP plugin may receive SNMP traps from different SNMP Agent devices and convert them to context events. Receiving of traps is enabled by turning on Receive SNMP Traps global configuration option of the plugin. If this option is enabled, LinkServer listens for SNMP Traps on port 162. Traps will be received from any SNMP device that is configured to send them to the IP address of LinkServer.

When a new SNMP trap is received from the server, it generates a trap event in the Administration context:

SNMP TRAP

Event Name	trap
Permissions:	Accessible at User permission level
Records:	1

Record Format:

Field Name

Field Type

Notes

agentAddress

String

SNMP Agent Address, i.e. IP address of the object generating the trap.

enterprise

String

Enterprise. Corporation or organization that originated the trap. This is the object identifier (OID) assigned to the vendor implementing the agent. Equals to the value of the sysObjectID variable, and it is unique for each implementer of an SNMP agent.

genericTrap

Integer

Generic Trap Type ID. Integer, as follows:

Value	Name	Description
0	coldStart	The agent is reinitializing. Configuration data or MIB variable values, or both, might have changed. Restart the measurement epochs.
1	warmStart	The agent is reinitializing but configuration data or MIB variable values have not changed.
2	linkDown	The agent has detected that a known communications interface has been disabled.
3	linkUp	The agent has detected that a known communications interface has been enabled.
4	authenticationFailure	A message was received that could not be authenticated.
5	egpNeighborLoss	An Exterior Gateway Protocol (EGP) neighbor was lost.
6	enterpriseSpecific	Vendor-specific trap. Specific Trap Type ID should be defined.

specificTrap

Integer

Specific Trap Type ID. Defined when Generic Trap Type is set to Enterprise.

timeStamp

Date

Elapsed time, in hundredths of a second, from the last reinitialization of the agent to the event generating the trap.

variableBindings

Data Table

Variable Bindings. Extra information, dependent on generic-trap type.