Software Queue
The software queuing strategy is configurable, and the next sections deal
with various techniques to do this. This is where you can influence the order
in which packets are scheduled into the TxQ and the number of packets sent.
When using queuing mechanisms, several different logical queues are
created, and traffic is placed into the appropriate software queue when it
arrives at the interface. Each software queue has size limits, and packets
above that limit are dropped.
Remember that fast-switched or CEF-switched traffic enters the software
queue only if the hardware queue is congested. Process-switched traffic
always goes into the software queue.