The adaptation rule provides the QoS provisioning system with the ability to adapt defined CIR and PIR administrative rates to the underlying capabilities of the hardware where the queue will be created on to derive the operational rates. The administrative CIR and PIR rates are translated to actual operational rates enforced by the hardware queue. The rule provides a constraint used when the exact rate is not available.
For the CIR and PIR parameters individually, the system attempts to find the best operational rate, depending on the defined constraint. The following constraints are supported:
minimum
The system finds the hardware supported rate that is greater than or equal to the specified rate.
maximum
The system finds the hardware supported rate that is less than or equal to the specified rate.
closest
The system finds the hardware supported rate that is closest to the specified rate.
Depending on the platform where the queue is provisioned, the actual operational CIR and PIR settings used by the queue depend on the method the hardware uses to implement and represent the mechanisms that enforce the CIR and PIR rates. The adaptation rule controls the method the system uses to choose the rate step based on the administrative rates defined by the rate command.
On 7210 SAS-D devices, for the supported CIR and PIR range values 0 to 1 Gb, the hardware rates are listed in the following table.
Hardware rate steps (kb/s) |
Rate range (kb/s) |
|---|---|
0 to 16770 kb/s |
|
16 kb/s |
16780 to 33540 kb/s |
32 kb/s |
33550 to 67090 kb/s |
64 kb/s |
67100 to 134180 kb/s |
128 kb/s |
134190 to 268360 kb/s |
256 kb/s |
268370 to 536730 kb/s |
512 kb/s |
536740 to 1000000 kb/s |
On 7210 SAS-Dxp devices, for supported CIR and PIR range values 0 to 10 Gb, the hardware rates are listed in the following table.
Hardware rate steps (kb/s) |
Rate range (kb/s) |
|---|---|
64 kb/s |
0 to 134144 kb/s |
256 kb/s |
134145 kb/s and above |
To illustrate how the adaptation rule constraints of minimum, maximum, and closest are evaluated in determining the operational CIR or PIR for the 7210 SAS, assume there is a queue where the administrative CIR and PIR values are 90 kb/s and 150 kb/s respectively.
If the adaptation rule is minimum, the operational CIR and PIR values are 128 kb/s and 192 kb/s respectively, as it is the native hardware rate greater than or equal to the administrative CIR and PIR values.
If the adaptation rule is maximum, the operational CIR and PIR values are 64 kb/s and 128 kb/s.
If the adaptation rule is closest, the operational CIR and PIR values are 64 kb/s and 128 kb/s, respectively, because those are the closest matches for the administrative values that are even multiples of the 64 kb/s rate step.