Alcatel-Lucent 7210 SAS E OS Quality Of Service Manual page 35

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 due to hardware implementation trade-offs.
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:
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•
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Depending on the hardware upon 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 7210 SAS uses a single rate step value of 64 kbps to define the granularity for both 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.
For the supported CIR/PIR range values 0 to 1Gb, the same hardware rate step of 64 kbps is used.
To illustrate how the adaptation rule constraints 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 90Kbps and 150 Kbps, respectively.
If the adaptation rule is minimum, the operational CIR and PIR values will be 128 Kbps and 192
Kbps 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 will be 64 Kbps and 128
Kbps.
If the adaptation rule is closest, the operational CIR and PIR values will be 64 Kbps and 128 Kbps,
respectively, as those are the closest matches for the administrative values that are even multiples
of the 64 Kbps rate step.
7210 SAS E OS Quality of Service Guide
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.
QoS Policies
Page 35