UMN:CLI
User Manual
V8102
356
9.3.10
Scheduling
To process incoming packets by the queue scheduler, the V8102 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 distin-
guished 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
7
4
1
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
7
7
6
4
4
3
3
3
1
Fig. 9.14
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.