3Com 10002211 manual Rmon Groups

RMON Groups B-5

History and The History group records periodic statistical samples from the network axFDDI Groups and stores them for retrieval at another time. The information available

per interface for each time interval includes:

■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 undersized but otherwise well-formed packets

■Number of received oversized but otherwise well-formed packets

■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

Alarms The CoreBuilder 6000 system supports the following syntax for alarms:

■Counters

■Gauges

■Integers

■Timeticks

These mechanisms report information about the network to the network administrator. Counters, for example, hold and update the number of occurrences of a particular event through a port, module, or switch on the network. Alarms monitor the counters and report instances of 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, reading counters can give you misleading results.

Counters are not infinite, which makes rate comparisons an efficient way to use them. When counters reach a predetermined limit, they return to 0 (roll over). A single low counter value might accurately represent a condition on the network. Or it might simply indicate that a roll over has occurred.