Configuring RMON

Overview

Remote Network Monitoring (RMON) is an enhancement to SNMP. It enables proactive remote monitoring and management of network devices and subnets. An RMON monitor periodically or continuously collects traffic statistics for the network attached to a port on the managed device. The managed device can automatically send a notification when a statistic crosses an alarm threshold, so the NMS does not need to constantly poll MIB variables and compare the results.

RMON uses SNMP notifications to notify NMSs of various alarm conditions such as broadcast traffic threshold exceeded. In contrast, SNMP reports function and interface operating status changes such as link up, link down, and module failure.

HP devices provide an embedded RMON agent as the RMON monitor. An NMS can perform basic SNMP operations to access the RMON MIB.

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. NMSs can obtain all RMON MIB information by using this method.

•RMON agents embedded in network devices—NMSs exchange data with RMON agents by using basic SNMP operations to gather network management information. Because this method is resource intensive, most RMON agent implementations provide only four groups of MIB information: alarm, event, history, and statistics.

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, HP implements the statistics group, history group, event group, and alarm group supported by the public MIB. HP also implements a private alarm group, which enhances the standard alarm group.

Ethernet statistics group

The statistics group defines that the system collects various traffic statistics on an interface (only Ethernet interfaces are supported), and saves the statistics in the Ethernet statistics table (ethernetStatsTable) for future retrieval. 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.

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