ZyXEL Communications Plumbing Product metrogigabit switch User Manual

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Chapter 22 Queuing Method
MGS3700-12C User’s Guide
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22.1.3  Weighted Round Robin Scheduling (WRR) 
Round Robin Scheduling services queues on a rotating basis and is activated only 
when a port has more traffic than it can handle. A queue is a given an amount of 
bandwidth irrespective of the incoming traffic on that port. This queue then moves 
to the back of the list. The next queue is given an equal amount of bandwidth, and 
then moves to the end of the list; and so on, depending on the number of queues 
being used. This works in a looping fashion until a queue is empty. 
Weighted Round Robin Scheduling (WRR) uses the same algorithm as round robin 
scheduling, but services queues based on their priority and queue weight (the 
number you configure in the queue Weight field) rather than a fixed amount of 
bandwidth. WRR is activated only when a port has more traffic than it can handle. 
Queues with larger weights get more service than queues with smaller weights. 
This queuing mechanism is highly efficient in that it divides any available 
bandwidth across the different traffic queues and returns to queues that have not 
yet emptied.