SNMP Reference Guide

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SNMP Traps
SNMP is frequently used to monitor systems for fault conditions such as temperature violations, hard drive failures, and
so on. Management applications can monitor for these conditions by polling the appropriate OIDs with the Get command
and analyzing the returned data. This method has its drawbacks. If it is done frequently, significant amounts of network
bandwidth can be consumed. If it is done infrequently, the response to the fault condition may not occur in a timely
fashion. SNMP traps avoid these limitations of the polling method.
An SNMP trap is an asynchronous event indicating that something significant has occurred. This is analogous to a
pager receiving an important message, except that the SNMP trap frequently contains all the information needed to
diagnose a fault.
Two drawbacks to SNMP traps are that they are sent using UDP, which is not a guaranteed delivery mechanism, and
that they are not acknowledged by the receiver.
An SNMP trap message contains the trap’s enterprise OID, the agent IP address, a generic trap ID, the specific trap ID,
a time stamp, and zero or more variable bindings (varbinds). The combination of an enterprise OID and a specific trap ID
uniquely identifies each Server Administrator-defined trap. A varbind consists of an OID and its value and provides
additional information about the trap.
In order for a management system to receive SNMP traps from a managed system, the node must be configured to send
traps to the management system. Trap destination configuration is dependent on the operating system. When this
configuration is done, a management application on the management system can wait for traps and act on them when
received.
For a list of traps supported by the Server Administrator Instrumentation Service, see Instrumentation Traps. For
information on Server Administrator Storage Management traps, see Storage Management Alert Reference.
For a list of traps supported by the Remote Access Controller, see RAC Traps, BMC Traps and iDRAC7 Traps.
Trap Variables
This section describes the variables both on Traditional and Enhanced varbinds that are sent to the management
console to provide additional information about a trap or alert generated by some event on your system. The trap
variables presented here apply to all Instrumentation and RAC traps. Trap variables are sent in the order listed and are
reserved for use only in traps. When a varbind is created for a trap variable, a zero is appended to the object ID (OID) to
create the OID for the varbind.
The messages associated with each alertMessage varbind are available in the Message Reference Guide and can be
found by matching the alert ID in the MIB to the event ID in the Message Reference Guide .
Table 1913. Trap Variables
Variable Name
alertSystem
Object ID 1.3.6.1.4.1.674.10892.1.5000.10.1
Description Identifies the system generating the alert.
Syntax DisplayString
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