204 C HAPTER 10: RMONWhat is RMON? RMON is the common abbreviation for Remote Monitoring, a systemdefined by the IETF that allows you to monitor the traffic of LANs orVLANs remotely.A typical RMON setup consists of two components: The RMON probe — An intelligent, remotely-controlled device orsoftware agent that continually collects statistics about a LANsegment or VLAN, and transfers the information to a managementworkstation on request or when a pre-defined threshold is crossed. The management workstation — Communicates with the RMONprobe and collects the statistics from it. The workstation does not haveto be on the same network as the probe and can manage the probeby in-band or out-of-band connections.The RMON Groups The IETF define nine groups of Ethernet RMON statistics. This sectiondescribes these groups, and details how they can be used.StatisticsThe Statistics group provides traffic and error statistics showing packets,bytes, broadcasts, multicasts and errors on a LAN segment or VLAN.Information from the Statistics group is used to detect changes in trafficand error patterns in critical areas of your network.HistoryThe History group provides historical views of network performance bytaking periodic samples of the counters supplied by the Statistics group.The group is useful for analyzing the traffic patterns and trends on a LANsegment or VLAN, and for establishing the normal operating parametersof your network.AlarmsThe Alarms group provides a mechanism for setting thresholds andsampling intervals to generate events on any RMON variable.Alarms are used to inform you of network performance problems andthey can trigger automated responses through the Events group.
