SNMP is frequently used to monitor systems for fault
conditions such as temperature violations, hard drive failures. 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 depends 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.
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NOTE: For the list
of storage management alerts and storage management messages, see
the
Dell OpenManage Server Administrator Messages Reference Guide available on the Dell Support site at dell.com/openmanagemanuals
navigate to
OpenManage Software and select the version required.