Scalability and performance are driven by the number of entities for which congestion monitoring is enabled on each line card.
Each statistics-gathering operation requires a show or read followed by a clear. The shorter the time between the two, the more accurate the information about the congestion state of the EPS is.
If the clear operation is not executed after the show or read operation, the external statistics gathering entity (external server) would need to perform additional operations (such as, subtract statistics between the two consecutive reads) to obtain the delta between the two reads.
The recommended minimum polling interval at a higher scale (high number of monitoring entities) is 15 minutes per monitoring entity.
If statistics are obtained via SNMP, the relevant MIB entries corresponding to the show command are:
tPortEgrVPortMonThrEntry
tPortEgrMonThrEntry
Clearing of the statistics can also be performed through a common MIB entry, corresponding to a clear command: tmnxClearEntry.