RMON 5-23About the RMON GroupsThe IETF define nine groups of Ethernet RMON sta-tistics. This section describes these groups, anddetails how they can be used.StatisticsThe Statistics group provides traffic and error statis-tics showing packets, bytes, broadcasts, multicastsand errors on a LAN segment or VLAN.Information from the Statistics group is used todetect changes in traffic and error patterns in criticalareas of your network.HistoryThe History group provides historical views of net-work performance by taking periodic samples ofthe counters supplied by the Statistics group. Thegroup features user-defined sample intervals andbucket counters for complete customization of trendanalysis.The group is useful for analysis of traffic patternsand trends on a LAN segment or VLAN, and toestablish baseline information indicating normaloperating parameters.AlarmsThe Alarms group provides a versatile, generalmechanism for setting thresholds and samplingintervals to generate events on any RMON variable.Both rising and falling thresholds are supported, andthresholds can be on the absolute value of a vari-able or its delta value. In addition, alarm thresholdsmay be autocalibrated or set manually.Alarms are used to inform you of a network perfor-mance problem and they can trigger automatedaction responses through the Events group.HostsThe Hosts group specifies a table of traffic anderror statistics for each host on a LAN segment orVLAN. Statistics include packets sent and received,octets sent and received, as well as broadcasts, mul-ticasts, and error packets sent.The group supplies a simple discovery mechanismlisting all hosts that have transmitted. The nextgroup, Hosts Top N, requires implementation of theHosts group.Hosts Top NThe Hosts Top N group extends the Hosts table byproviding sorted host statistics, such as the top 20nodes sending packets or an ordered list of allnodes according to the errors they sent over the last24 hours.
