3Com 4210 PWR Configuration Manual page 364

362 C 34: RMON C
HAPTER
Commonly Used RMON
Groups
ONFIGURATION
managed network devices are connected. Thus, the NMS can further manage the
networks.
Event group
Event group is used to define the indexes of events and the processing methods of
the events. The events defined in an event group are mainly used by entries in the
alarm group and extended alarm group to trigger alarms.
You can specify a network device to act in one of the following ways in response
to an event:
Logging the event
■
Sending trap messages to the NMS
■
Logging the event and sending trap messages to the NMS
■
No processing
■
Alarm group
RMON alarm management enables monitoring on specific alarm variables (such as
the statistics of a port). When the value of a monitored variable exceeds the
threshold, an alarm event is generated, which then triggers the network device to
act in the way defined in the events. Events are defined in event groups.
With an alarm entry defined in an alarm group, a network device performs the
following operations accordingly:
Sampling the defined alarm variables periodically
■
Comparing the samples with the threshold and triggering the corresponding
■
events if the former exceed the latter
Extended alarm group
With extended alarm entry, you can perform operations on the samples of alarm
variables and then compare the operation results with the thresholds, thus
implement more flexible alarm functions.
With an extended alarm entry defined in an extended alarm group, the network
devices perform the following operations accordingly:
Sampling the alarm variables referenced in the defined extended alarm
■
expressions periodically
Performing operations on the samples according to the defined expressions
■
Comparing the operation results with the thresholds and triggering
■
corresponding events if the operation result exceeds the thresholds.
History group
After a history group is configured, the Ethernet switch collects network statistics
information periodically and stores the statistics information temporarily for later
use. A history group can provide the history data of the statistics on network
segment traffic, error packets, broadcast packets, and bandwidth utilization.