H3C Technologies H3C MSR 50 - Manual (Page 30)

History group
The history group defines that the system periodically collects traffic statistics on interfaces and saves the
statistics in the history record table (ethernetHistoryTable). The statistics include bandwidth utilization,
number of error packets, and total number of packets.
The history statistics table record traffic statistics collected for each sampling interval. The sampling
interval is user-configurable.
Event group
The event group defines event indexes and controls the generation and notifications of the events
triggered by the alarms defined in the alarm group and the private alarm group. The events can be
handled in one of the following ways:
• Log—Logs event information (including event name and description) in the event log table of the
RMON MIB, so the management device can get the logs through the SNMP Get operation.
• Trap—Sends a trap to notify an NMS of the event.
• Log-Trap—Logs event information in the event log table and sends a trap to the NMS.
• None—No action.
Alarm group
The RMON alarm group monitors alarm variables, such as the count of incoming packets (etherStatsPkts)
on an interface. After you define an alarm entry, the system gets the value of the monitored alarm
variable at the specified interval. If the value of the monitored variable is greater than or equal to the
rising threshold, a rising event is triggered. If the value of the monitored variable is smaller than or equal
to the falling threshold, a falling event is triggered. The event is then handled as defined in the event
group.
If an alarm entry crosses a threshold multiple times in succession, the RMON agent generates an alarm
event only for the first crossing. For example, if the value of a sampled alarm variable crosses the rising
threshold multiple times before it crosses the falling threshold, only the first crossing triggers a rising alarm
event, as shown in Figure 6 .
Figure 6 Rising and falling alarm events
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