3Com CoreBuilder 2500 User Manual - page 219
RMON Groups
15-5
History and
axFDDIHistory
Groups
The history and axFDDIHistory groups record periodic statistical samples
for Ethernet and FDDI interfaces and store them for later retrieval. The
information available per interface for each time interval includes these
statistics:
■
Number of received octets
■
Number of received packets
■
Number of received broadcast packets
■
Number of received multicast packets
■
Number of received packets with CRC or alignment errors
■
Number of received packets that are undersized but otherwise
well-formed
■
Number of received packets that are oversized but otherwise
well-formed
■
Number of detected transmit collisions
■
Estimate of the mean physical layer network utilization
Alarm Group
The CoreBuilder 2500 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.