3Com 10002211 manual RMON Hysteresis Mechanism

RMON Groups B-7

You can associate an alarm with the high threshold, the low threshold, or both. The actions taken because of an alarm depend on the network management application.

RMON Hysteresis Mechanism

The RMON hysteresis mechanism provides a way to prevent small fluctuations in counter values from causing alarms. This mechanism generates an alarm only under the following conditions:

■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 exceeds the low threshold after previously exceeding the high threshold. (An alarm does not occur if the value has not risen above the high threshold before falling below the low threshold.)

In Figure B-1, for example, an alarm occurs the first time the counter exceeds the high threshold, but not at the second time. At the first instance, the counter is rising from below the low threshold, while in the second instance, it is not.

Host Group The Host Group records statistics for each host, denoted by the host’s physical MAC address, detected on the network. The information available from this group for each discovered host 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

■hostTimeTable that provides all these statistics in a format indexed by the relative order in which the host was discovered. Host Group adds new hosts to the end of this table.