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History Group
The History group records periodic statistical samples from the
collision domain and stores them in an SNMP table for later
retrieval.
The History group allows the manager to set a timer to record
samples of Ethernet statistics. It allows baselining of network
activity over time.
Once samples are taken, the sample data is stored in an entry in
a media-specific table. Each such entry defines one sample and
is associated with the historyControl entry that caused the
sample to be taken. The only media-specific table defined is the
etherHistoryTable for Ethernet networks.
Alarm Group
The Alarm group periodically takes statistical samples from
variables and compares them to previously configured
thresholds. The alarm table stores configuration entries, each of
which defines a polling period and various threshold values.
If a monitored variable exceeds a threshold value, the switch
generates an event. No more events are generated for that
threshold until the opposite threshold is exceeded.
You can limit the generation of events via the MIB. When
sampling a delta value, you can increase the precision of the
sample by taking the sample twice per period and comparing
the sum of the latest two samples to the threshold. This allows
the switch to detect threshold crossings that span the sampling
boundary. This does not require any special configuration of
the threshold value.
This group requires the implementation of the Event Group.
book Page 2 Monday, March 2, 1998 4:27 PM