Service/Subscriber Or Multi-Service Site Egress Port Bandwidth Allocation - Alcatel-Lucent 7450 Quality Of Service Manual

Overview
When a queue is inactive or has a limited offered load that is below its fair share (fair share
is based on the bandwidth allocation a queue would receive if it was registering adequate
activity), its operational PIR must be set to some value to handle what would happen if the
queues offered load increased prior to the next iteration of the port virtual scheduling
algorithm. If an inactive queues PIR was set to zero (or near zero), the queue would throttle
its traffic until the next algorithm iteration. If the operational PIR was set to its configured
rate, the result could overrun the expected aggregate rate of the port scheduler.
To accommodate inactive queues, the system calculates a Minimum Information Rate (MIR)
for each queue. To calculate each queue's MIR, the system determines what that queue's Fair
Information Rate (FIR) would be if that queue had actually been active during the latest
iteration of the virtual scheduling algorithm. For example, if three queues are active (1, 2, and
3) and two queues are inactive (4 and 5), the system first calculates the FIR for each active
queue. Then it recalculates the FIR for queue 4 assuming queue 4 was active with queues 1,
2, and 3 and uses the result as the queue's MIR. The same is done for queue 5 using queues
1, 2, 3, and 5. The MIR for each inactive queue is used as the operational PIR for each queue.
Service/Subscriber or Multi-service Site Egress Port Bandwidth
Allocation
The port-based egress scheduler can be used to allocate bandwidth to each service or
subscriber or multi-service site associated with the port. While egress queues on the service
can have a child association with a scheduler policy on the SAP or multi-service site, all
queues must vie for bandwidth from an egress port. Two methods are supported to allocate
bandwidth to each service or subscriber or multi-service site queue:
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1. Service or subscriber or multi-service site queue association with a scheduler on the
SAP or multi-service site which is itself associated with a port-level scheduler.
2. Service or subscriber or multi-service site queue association directly with a port-level
scheduler.
Quality of Service Guide