Zilog EZ80F91GA - Manual (Page 51)

UM024502-1012 ZGATE Threshold Filtering Configuration Page
ZGATE Embedded Security Development Kit
User Manual
39
The Threshold Filtering Configuration page lists the Interval parameter, which represents
the number of seconds during which ZGATE tracks the number of packets originating
from a particular source IP address. The minimum interval is 10 seconds and the maxi-
mum interval is 1800 seconds (30 minutes).
Upper Threshold marks the point at which ZGATE will start discarding packets from a
particular node. In Figure 10, this Upper Threshold is set to 2000 and the interval is 240
seconds. Therefore, if a node attempts to send ZTP more than 2000 packets within 240
seconds, ZGATE will start filtering packets from that source.
When the upper threshold is crossed, ZGATE will continue to filter packets from the
source IP address until the source lowers its transmission rate to less than the lower thresh-
old. In Figure 10, this lower threshold is 500, meaning that after threshold filtering for a
particular source IP address has been engaged, it will remain engaged until the source
sends ZTP fewer than 500 packets in a 240-second interval.
The Lower and Upper thresholds are related, and values entered must follow the restric-
tions displayed on the page; i.e., the Lower threshold must contain a value of 20 or greater,
Figure 10. The Threshold Filtering Configuration Page