The schedulers on the network processor can only operate with a finite set of rates. These rates are called the operational rates. The configured rates for PIR and CIR do not necessarily correspond to the operational rates. In order to offer maximum flexibility to the user, the adaptation-rule command can be used to choose how an operational rate is selected based on the configured PIR or CIR rate.
The max parameter causes the network processor to be programmed at an operational rate that is less than the configured PIR or CIR rate by up to 1.0%. The min parameter causes the network processor to be programmed at an operational rate that is greater than the configured PIR or CIR rate by up to 1.0%. The closest parameter causes the network processor to be programmed at an operational rate that is closest to the configured PIR or CIR rate.
A 4-priority scheduler on the network processor of a third-generation (Gen-3) Ethernet adapter card or platform can be programmed at an operational CIR rate that exceeds 1.0% of the configured CIR rate. The PIR rate (that is, the maximum rate for the queue) and the SAP aggregate rates (CIR and PIR), maintain an accuracy of +/- 1.0% of the configured rates.
The average difference between the configured CIR rate and the programmed (operational) CIR rate is as follows:
2.0% for frame sizes that are less than 2049 bytes
4.0% for other frame sizes
The percentages in the above list are averages only; the actual values can be higher.
The Gen-3 network processor PIR rate is programmed to an operational PIR rate that is within 1.0% of the configured rate, which ensures that the FC/CoS queue does not exceed its fair share of the total bandwidth.