3Com CoreBuilder 3500, Implementation Manual, Page: 551 / 592

Remote Monitoring (RMON) 551
RMON Hysteresis Mechanism The RMON hysteresis mechanism
prevents small fluctuations in counter values from causing alarms. Alarms
occur only when either:
■
The counter value exceeds the high threshold after previously falling
below the low threshold. (An alarm does not occur if the value has not
fallen below the low threshold before rising above the high threshold.)
■
The counter value falls below the low threshold after previously
exceeding the high threshold. (An alarm does not occur if the value
has not first risen above the high threshold.)
For example, in Figure 97, an alarm occurs the first time that the counter
exceeds the high threshold, but not the second time. At the first instance,
the counter is rising from below the low threshold. In the second
instance, the counter is not rising from below the low threshold.
Host Group
The host group records the following statistics for each host (the host
group detects hosts on the network by their physical MAC addresses):
■
Number of received packets
■
Number of transmitted packets
■
Number of received octets
■
Number of transmitted octets
■
Number of transmitted broadcast packets
■
Number of transmitted multicast packets
These statistics, indexed by relative order in which the hosts are
discovered, appear in
hostTimeTable .
HostTopN Group
The HostTopN group reports on hosts that top a list that is sorted in order
of one of their statistics. Information from this group includes:
■
Number of received packets
■
Number of transmitted packets
■
Number of received octets
■
Number of transmitted octets
■
Number of transmitted broadcast packets
■
Number of transmitted multicast packets