3Com corebuilder 3500 Implementation Manual page 549

Number of received packets that are undersized but otherwise
well-formed
Number of received packets that are oversized but otherwise
well-formed
Number of received undersized packets with either a CRC or an
alignment error
Number of detected transmit collisions
Estimate of the mean physical layer network utilization
Alarm Group
The system supports the following RMON alarm mechanisms:
Counters
Gauges
Integers
Timeticks
These RMON MIB objects yield alarms when the network exceeds
predefined limits. The most frequently used objects are counters,
although the other objects may be used in much the same way. The
balance of this chapter illustrates RMON functions using counters.
Counters hold and update the number of times an event occurs on a
port, module, or switch. Alarms monitor the counters and report when
counters exceed their set threshold.
Counters are useful when you compare their values at specific time
intervals to determine rates of change. The time intervals can be short or
long, depending on what you measure.
Occasionally, counters can produce misleading results. Because counters
are finite, they are useful for comparing rates. When counters reach a
predetermined limit, they roll over (that is, return to 0). A single low
counter value may accurately represent a condition on the network. On
the other hand, the same value may simply indicate a rollover.
When you disable a port, the application may not update some of its
associated statistics counters.
Remote Monitoring (RMON) 549