Alcatel-Lucent 7950 Quality Of Service Manual page 462

Configuring Port Scheduler Policies
service level scheduler is a scheduler instance at the SAP, multi-service site
operate based on packet overhead which does not include the IFG or preamble on Ethernet
packets. In order for the port based virtual scheduling algorithm to function, it must convert the
queue and service scheduler packet based required bandwidth and bandwidth limiters (CIR and
rate PIR) to frame based values. This is accomplished by adding 20 bytes to each Ethernet frame
offered at the queue level to calculate a frame based offered load. Then the algorithm calculates
the ratio increase between the packet based offered load and the frame based offered load and uses
this ratio to adapt the CIR and rate PIR values for the queue to frame-CIR and frame-PIR values.
When a service level scheduler hierarchy is between the queues and the port based schedulers, the
ratio between the average frame-offered-load and the average packet-offered-load is used to adapt
the scheduler's packet based CIR and rate PIR to frame based values. The frame based values are
then used to distribute the port based bandwidth down to the queue level.
Page 462 7950 XRS Quality of Service Guide
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