H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 77)

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Configuring RMON
This chapter describes how to configure RMON.
Overview
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, logs the crossing event and sends 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. Because this approach is
resource intensive, most RMON agent implementations provide only four groups of MIB information:
alarm, event, history, and statistics.
H3C 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 RFC 2819 defined RMON groups, H3C implements the statistics group, history group, event
group, and alarm group supported by the public MIB. H3C also implements a private alarm group,
which enhances the standard alarm group.
Ethernet statistics group
The statistics group defines that the system collects traffic statistics on interfaces (only Ethernet interfaces
are supported) and saves the statistics in the Ethernet statistics table (ethernetStatsTable). The interface
traffic statistics include network collisions, CRC alignment errors, undersize/oversize packets, broadcasts,
multicasts, bytes received, and packets received.
After you create a statistics entry for an interface, the statistics group starts to collect traffic statistics on the
interface. The statistics in the Ethernet statistics table are cumulative sums.