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Queuing Overview 307
By default, queues evenly balance traffic. There are two thresholds by which queues are
measured: queue limit and byte count. The queue limit default is 20 records. The byte count
limit default is 1500 bytes. Whichever limit is hit first signifies the end of a particular queue's
time with the processor.
Note that the router does not fragment a packet just to meet queue limit or byte count
conditions. For instance, if the byte count limit is reached during the transmission of a packet,
the entire packet is dispatched, not just cut short. Figure 10-6 illustrates the custom queuing
concept.
Figure 10-6
Custom Queuing
To provide what is in essence a higher priority to any particular traffic type, the limits for that
queue can be increased. For instance, if FTP is a high priority, the queue limit and byte count
can be increased to give it a higher percentage of bandwidth and processor time.
Queue X
Packet in
queue?
Over
service
threshold
Dispatch packet and
increment service
threshold counters
Next queue
No
Yes
Yes
No
Reset
sevice
threshold
counters