QoS Policies
7210 SAS D, E, K OS Quality of Service Guide Page 43
PIR for the queues of the forwarding class is defined as a percentage of the network interface
bandwidth.
When defining the PIR for a queue, the value specified is the administrative PIR for the queue.
The user has some control over how the administrative PIR is converted to an operational PIR
should the hardware not support the exact CIR and PIR values specified. The interpretation of the
administrative PIR is discussed below in Adaptation Rule for Queues on page 47
Adaptation Rule for Queues
The adaptation rule provides the QoS provisioning system with the ability to adapt specific CIR
and PIR defined administrative rates to the underlying capabilities of the hardware 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 will attempt to find the best operational
rate depending on the defined constraint. The supported constraints are:
• Minimum — Find the hardware supported rate that is equal to or higher than the specified
rate.
• Maximum — Find the hardware supported rate that is equal to or lesser than the specified
rate.
• Closest — Find the hardware supported rate that is closest to the specified rate.
Depending on the platform on which the queue is provisioned, the actual operational CIR and PIR
settings used by the queue will be dependant 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.
In 7210 SAS-E devices, for the supported CIR/PIR range values 0 to 1Gb, the same hardware rate
step of 64 kbps is used.
In 7210 SAS-D devices, for the supported CIR/PIR range values 0 to 1Gb, the hardware rate is
shown in Table 9.
Table 9:
Supported Hardware Rates and CIR/PIR Values for 7210 SAS-D and E devices
Hardware Rate Steps Rate Range (kbps)
Kb/sec 0 - 16770 kbps
16kbps
16780 - 33540 kbps
32kbps
33550 - 67090 kbps
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