3com 4210 PWR 9-Port 3CR17341-91-ME 用户手册

C

HAPTER

 34: RMON C

ONFIGURATION

managed network devices are connected. Thus, the NMS can further manage the 
networks.

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

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

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.

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.