Alcatel-Lucent 7450 Quality Of Service Manual page 886

Ethernet service switch; service router; extensible routing system

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Table of Contents

Above CIR Distribution

'Above CIR' distribution is the second phase of bandwidth allocation between a parent

scheduler and its child queues and child schedulers. The bandwidth that is available to the

parent scheduler after the 'within CIR' distribution is distributed among the child members

using each child's level (to define strict priority for the above CIR distribution), Weight (the

ratio at a given level with several children) and the child's rate value. A rate value equal to

the child's CIR value results in a child not receiving any bandwidth during the 'above CIR'

distribution phase.

Available Bandwidth

Available bandwidth is the bandwidth usable by a parent scheduler to distribute to its child

queues and schedulers. The available bandwidth is limited by the parent's schedulers

association with its parent scheduler. If the parent scheduler has a parent of its own and the

parent schedulers defined rate value, then available bandwidth is distributed to the child

queues and schedulers using a 'within CIR' distribution phase and an 'above CIR'

distribution phase. Distribution in each phase is based on a combination of the strict priority

of each child and the relative weight of the child at that priority level. Separate priority and

weight controls are supported per child for each phase.

The Committed Burst Size (CBS) specifies the relative amount of reserved buffers for a

specific ingress network XMA or MDA forwarding class queue or egress network port

forwarding class queue. The value is entered as a percentage.

The Committed Information Rate (CIR) defines the amount of bandwidth committed to the

scheduler or queue.

For schedulers, the CIR value can be explicitly defined or derived from summing the

child member CIR values.

On a queue, the CIR value is explicitly defined.

Quality of Service Guide