Working Mechanism; Rmon Groups - 3Com S7906E Configuration Manual

Working Mechanism

RMON allows multiple monitors (management devices). A monitor provides two ways of data gathering:
Using RMON probes. Management devices can obtain management information from RMON
probes directly and control network resources. In this approach, management devices can obtain
all RMON MIB information.
Embedding RMON agents in network devices such as routers, switches, and hubs to provide the
RMON probe function. Management devices exchange data with RMON agents using basic SNMP
operations to gather network management information, which, due to system resources limitation,
may not cover all MIB information but four groups of information, alarm, event, history, and
statistics, in most cases.
The 3Com device adopts the second way and realizes the RMON agent function.
function, the management device can monitor all the traffic flowing among the managed devices on all
connected LAN segments; obtain information about error statistics and performance statistics for network
management.

RMON Groups

Among the RMON groups defined by RMON specifications (RFC 2819), the realized public MIB of the
device supports the event group, alarm group, history group and statistics group. Besides, 3Com also
defines and implements the private alarm group, which enhances the functions of the alarm group. This
section describes the five kinds of groups in general.
Ethernet statistics group
The statistics group defines that the system collects statistics on various traffic information on an
interface (at present, only Ethernet interfaces are supported) and saves the statistics in the Ethernet
statistics table (ethernetStatsTable) for query convenience of the management device. It provides
statistics about network collisions, CRC alignment errors, undersize/oversize packets, broadcasts,
multicasts, bytes received, packets received, and so on.
After the creation of a statistics entry on an interface, the statistics group starts to collect traffic statistics
on the interface. The result of the statistics is a cumulative sum.
History group
The history group defines that the system periodically collects statistics on traffic information at an
interface and saves the statistics in the history record table (ethernetHistoryTable) for query
convenience of the management device. The statistics data includes bandwidth utilization, number of
error packets, and total number of packets.
A history group collects statistics on packets received on the interface during each period, which can be
configured through the command line interface (CLI).
Event group
The event group defines event indexes and controls the generation and notifications of the events
triggered by the alarms defined in the alarm group and the private alarm group. The events can be
handled in one of the following ways:
Log: Logging event related information (the occurred events, contents of the event, and so on) in
the event log table of the RMON MIB of the device, and thus the management device can check the
logs through the SNMP Get operation.
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With the RMON agent