RMON configuration
RMON overview
Introduction
Remote Monitoring (RMON) is an enhancement to SNMP for remote device management and traffic
monitoring. An RMON monitor, typically the RMON agent embedded in a network device, periodically
or continuously collects traffic statistics for the network attached to a port, and when a statistic crosses a
threshold, log the crossing event and send a trap to the management station.
RMON uses SNMP traps to notify NMSs of exceptional conditions. RMON SNMP traps report various
events, including traffic events such as broadcast traffic threshold exceeded. In contrast, SNMP standard
traps report device operating status changes such as link up, link down, and module failure.
RMON enables proactive monitoring and management of remote network devices and subnets. The
managed device can automatically send a trap when a statistic crosses an alarm threshold, and the
NMS does not need to constantly poll MIB variables and compare the results. As a result, network traffic
is reduced.
Working mechanism
RMON monitors typically take one of the following forms:
• Dedicated RMON probes. NMSs can obtain management information from RMON probes
directly and control network resources. In this approach, NMSs can obtain all RMON MIB
information.
• RMON agents embedded in network devices. NMSs exchange data with RMON agents by using
basic SNMP operations to gather network management information. This approach consumes the
resources of managed network devices, and most RMON agent implementations only provide four
groups of MIB information, alarm, event, history, and statistics.
HP devices provide the embedded RMON agent function. You can configure your device to collect and
report traffic statistics, error statistics, and performance statistics.
RMON groups
Among the RMON groups defined by RMON specifications (RFC 2819), the device uses the statistics
group, history group, event group, and alarm group supported by the public MIB. HP also defines and
implements the private alarm group, which enhances the functions of the alarm group.
Ethernet statistics group
The statistics group defines that the system collects statistics of various traffic information on an Ethernet
interface and saves the statistics in the Ethernet statistics table (ethernetStatsTable) for query convenience
of the management switch. 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.
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