1-2z Using RMON probes. Management devices can obtain management information from RMONprobes directly and control network resources. In this approach, management devices can obtainall RMON MIB information.z Embedding RMON agents in network devices such as routers, switches, and hubs to provide theRMON probe function. Management devices exchange data with RMON agents using basic SNMPoperations to gather network management information, which, due to system resources limitation,may not cover all MIB information but four groups of information, alarm, event, history, andstatistics, in most cases.The device adopts the second way and realizes the RMON agent function. By using this function, themanagement devices can obtain information about traffic size, error statistics, and performancestatistics for network management.RMON GroupsAmong the RMON groups defined by RMON specifications (RFC 2819), the realized public MIB of thedevice supports the event group, alarm group, history group and statistics group. Besides, H3C alsodefines and implements the private alarm group, which enhances the functions of the alarm group. Thissection describes the five kinds of groups in general.Event groupThe event group defines event indexes and controls the generation and notifications of the eventstriggered by the alarms defined in the alarm group and the private alarm group. The events can behandled in one of the following ways:z Log: Logging event related information (the occurred events, contents of the event, and so on) inthe event log table of the RMON MIB of the device, and thus the management device can check thelogs through the SNMP GET operation.z Trap: Sending traps to notify the occurrence of this event to the network management stations(NMSs).z Log-Trap: Logging event information in the event log table and sending traps to NMSs.z None: No actionAlarm groupThe RMON alarm group monitors specified alarm variables, such as total number of received packets(etherStatsPkts) on a port. After you define an alarm entry the system gets the value of the monitoredalarm variable at the specified interval, when the value of the monitored variable is greater than or equalto the upper threshold, an upper event is triggered; when the value of the monitored variable is smallerthan or equal to the lower threshold, a lower event is triggered. The event is then handled as defined inthe event group.If a sampled alarm variable overpasses the same threshold multiple times, only the first one can causean alarm event. That is, the rising alarm and falling alarm are alternate.
