The specified lookup rate can be met in most cases, but the lookup rate decreases in cases where the average number of matches per lookup is high.
The variable rate STCAM cannot always process Lookup Requests at the
defined lookup rate. This happens if the lookup key matches more than MAX(2, TDM_FACTOR) entries. If there are many Lookup
Requests matching many entries in a short period of time, flow control applies on
the Lookup Request Interface. The defined lookup rate can also exceed if less than
MAX(2, TDM_FACTOR) entries match. This allows
the variable rate STCAM to catch up. Exceeding the defined lookup rate is possible
only if LOOKUP_INTERFACE_FREQ >
LOOKUP_RATE.
It is recommended to set the LOOKUP_INTERFACE_FREQ 10 to 20% higher than the LOOKUP_RATE. No management requests are served until
the Lookup Request FIFO is cleared. ECC scrubbing takes place only when both the
Lookup Request FIFO and the Management Request FIFO are emptied. The normal case is
when the lookup key matches few entries and the defined lookup rate is met. The
management request rate value in such cases is more than or equal to the following
value: