UMN:CLI User Manual
V5808
200
7.5.9 Scheduling
To process incoming packets by the queue scheduler, the V5808 provides the scheduling
algorithm as Strict Priority Queuing (SP), Weighted Round Robin (WRR) and Deficit
Round Robin (DRR).
Strict Priority Queuing (SP)
SPQ processes first more important data than the others. Since all data are processed by
their priority, data with high priority can be processed fast but data without low priority
might be delayed and piled up. This method has a strong point of providing the
distinguished service with a simple way. However, if the packets having higher priority
enter, the packets having lower priority are not processed.
3
7
6
7
741
The processing order in Strict Priority Queuing in case of entering
packets having the Queue numbers as below
3
3
4
7
Output Scheduler
Lowest priority highest priority
7 7 776443 3 31
Fig. 7.10 Strict Priority Queuing
Deficit Round Robin (DRR)
DRR is a modified WRR. This can handle packets of variable size without knowing their
mean size. A maximum packet size number is subtracted from the packet length, and
packets that exceed that number are held back until the next visit of the scheduler.
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