Connectivity Guide
ORG(3)
DOD(6)
INTERNET(1)
MGMT(2)
MIB(1)
EXPERIMENTA
L(3)
PRIVATE(4)
ENTERPRISES(1
)
DELL (674)
SNMPv2(6)
In the preceding example, the OID prex for the Dell enterprise would be 1.3.6.1.4.1.674.
The numbers in boldface type show the categories and numbers that apply to Server Administrator. All Server Administrator-dened
OIDs consist of 1.3.6.1.4.1.674 followed by additional component values.
SNMP Security
SNMP version 1 has a very limited security mechanism. SNMP agents support the use of a community string, which is congured at
each SNMP agent and is passed as a part of all SNMP request messages. There is no verication that the requester is actually a
member of the specied community. As most system and network management data is not condential, this limited security is
acceptable for Get types of requests. On the other hand, this security is not acceptable for Set types of operations where an SNMP
request could power o a system, recongure a redundant array of independent disks (RAID) card, and so on. Dell has chosen not to
support SNMP Set operations for this reason.
NOTE: The default SNMP agent conguration usually includes a SNMP community name such as public. For security
reasons, change the SNMP community names from their default values. For information about changing SNMP
community names, see the
Dell OpenManage Server Administrator User’s Guide
available on the Dell Support website at
dell.com/openmanagemanuals.
NOTE: As of iDRAC7 rmware release r1.30.30, iDRAC7 supports SNMP query operations (GET, GETNEXT, GETBULK)
via the SNMPv3 protocol, in addition to supporting query operations via the SNMP v1 and SNMP v2c protocols. More
specically, iDRAC7 now supports the SNMP User Security Model (USM).
SNMP Traps
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, signicant 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 signicant 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 specic trap ID, a time stamp,
and zero or more variable bindings (varbinds). The combination of an enterprise OID and a specic trap ID uniquely identies each
Server Administrator-dened trap. A varbind consists of an OID and its value and provides additional information about the trap.
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