User's Manual

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Figure 4-1 ASN.1 Tree Instance
In this figure, the OID of the object A is 1.2.1.1. NMS can locate this object through this unique OID and gets
the standard variables of the object. MIB defines a set of standard variables for monitored network devices by
following this structure.
If the variable information of Agent MIB needs to be browsed, the MIB browse software needs to be run on the
NMS. MIB in the Agent usually consists of public MIB and private MIB. The public MIB contains public network
management information that can be accessed by all NMS; private MIB contains specific information which
can be viewed and controlled by the support of the manufacturers.
MIB-I [RFC1156] is the first implemented public MIB of SNMP, and is replaced by MIB-II [RFC1213]. MIB-II
expands MIB-I and keeps the OID of MIB tree in MIB-I. MIB-II contains sub-trees which are called groups.
Objects in those groups cover all the functional domains in network management. NMS obtains the network
management information by visiting the MIB of SNMP Agent.
The switch can operate as a SNMP Agent, and supports both SNMP v1/v2c and SNMP v3. The switch
supports basic MIB-II, RMON public MIB and other public MID such as BRIDGE MIB. Besides, the switch
supports self-defined private MIB.
4.4.3 Introduction to RMON
RMON is the most important expansion of the standard SNMP. RMON is a set of MIB definitions, used to
define standard network monitor functions and interfaces, enabling the communication between SNMP
management terminals and remote monitors. RMON provides a highly efficient method to monitor actions
inside the subnets.
MID of RMON consists of 10 groups. The switch supports the most frequently used group 1, 2, 3 and 9:
 Statistics: Maintain basic usage and error statistics for each subnet monitored by the Agent.
 History: Record periodical statistic samples available from Statistics.
 Alarm: Allow management console users to set any count or integer for sample intervals and alert
thresholds for RMON Agent records.
 Event: A list of all events generated by RMON Agent.