Adaptation rule

The adaptation rule provides the QoS provisioning system with the ability to adapt specific FIR-, CIR-, and PIR-defined administrative rates to the underlying capabilities of the hardware that the queue is created on to derive the operational rates. The administrative FIR, CIR, and PIR rates are translated to operational rates enforced by the hardware queue. The adaptation rule provides a constraint used when the exact rate is not available because of hardware implementation trade-offs.

For the FIR, CIR, and PIR parameters individually, the system attempts to find the best operational rate depending on the defined constraint. The supported constraints are:

minimum

finds the hardware supported rate that is equal to or higher than the specified rate

maximum

finds the hardware supported rate that is equal to or lesser than the specified rate

closest

finds the hardware supported rate that is closest to the specified rate

Depending on the hardware on which the queue is provisioned, the operational FIR, CIR, and PIR settings used by the queue depends on the method that the hardware uses to implement and represent the mechanisms that enforce the FIR, CIR, and PIR rates.

As the hardware has a very granular set of rates, Nokia’s recommended method to determine which hardware rate is used for a queue is to configure the queue rates with the associated adaptation rule and use the show pools output command to display the rate achieved.

To illustrate how the adaptation rule constraints (minimum, maximum, and closest) are evaluated in determining the operational CIR or PIR rates, assume there is a queue on an IOM3-XP where the administrative CIR and PIR rates are 401 Mb/s and 403 Mb/s, respectively.

The following output shows the operating CIR and PIR rates achieved for the different adaptation rule settings:

*A:PE# # queue using default adaptation-rule=closest
*A:PE# show qos sap-egress 10 detail | match expression "Queue-Id|CIR Rule"
Queue-Id             : 1                Queue-Type           : auto-expedite
PIR Rule             : closest          CIR Rule             : closest
*A:PE#
*A:PE# show pools 1/1/1 access-egress service 1 | match expression "PIR|CIR"
Admin PIR        : 403000               Oper PIR         : 403200
Admin CIR        : 401000               Oper CIR         : 401600
*A:PE#
*A:PE# configure qos sap-egress 10 queue 1 adaptation-rule pir max cir max
*A:PE#
*A:PE# show qos sap-egress 10 detail | match expression "Queue-Id|CIR Rule"
Queue-Id             : 1                Queue-Type           : auto-expedite
PIR Rule             : max              CIR Rule             : max
*A:PE#
*A:PE# show pools 1/1/1 access-egress service 1 | match expression "PIR|CIR"
Admin PIR        : 403000               Oper PIR         : 401600
Admin CIR        : 401000               Oper CIR         : 400000
*A:PE#
*A:PE# configure qos sap-egress 10 queue 1 adaptation-rule pir min cir min
*A:PE#
*A:PE# show qos sap-egress 10 detail | match expression "Queue-Id|CIR Rule"
Queue-Id             : 1                Queue-Type           : auto-expedite
PIR Rule             : min              CIR Rule             : min
*A:PE#
*A:PE# show pools 1/1/1 access-egress service 1 | match expression "PIR|CIR"
Admin PIR        : 403000               Oper PIR         : 403200
Admin CIR        : 401000               Oper CIR         : 401600
*A:PE#