To properly understand more complicated configurations it is
necessary to explain a few concepts first. Because of the
complexity and the relative youth of the subject, a lot of
different words are used when people in fact mean the same
thing. The following is loosely based on draft-ietf-diffserv-
model-06.txt, An Informal Management Model for Diffserv Routers.
It can currently be found at http://www.ietf.org/internet-
drafts/draft-ietf-diffserv-model-06.txt. Read it for the strict
definitions of the terms used. An algorithm that manages the
queue of a device, either incoming (ingress) or outgoing
(egress). The root qdisc is the qdisc attached to the device. A
qdisc with no configurable internal subdivisions. A classful
qdisc contains multiple classes. Some of these classes contains
a further qdisc, which may again be classful, but need not be.
According to the strict definition, pfifo_fast *is* classful,
because it contains three bands which are, in fact, classes.
However, from the user's configuration perspec