Legacy Queuing Techniques
Queuing mechanisms allow you to control the way congested traffic is
buffered and send out the interface by placing each type of traffic in its own
queue. The router or switch then services each queue, scheduling transmittal
of its traffic, according to a configured policy.
FIFO Queuing
By default, most interfaces use FIFO queuing—there is just one software
queue, and traffic is buffered and then scheduled onto the interface in the
order it is received.
Note
Serial interfaces of E1 speed and below use weighted fair queuing by default, rather than FIFO
queuing.