NAME

       pfifo_fast - three-band first in, first out queue

DESCRIPTION

       pfifo_fast is the default qdisc of each interface.

       Whenever an interface is created, the pfifo_fast qdisc is automatically used as a queue. If another qdisc
       is attached, it preempts the default pfifo_fast, which automatically returns to function when an existing
       qdisc is detached.

       In this sense this qdisc is magic, and unlike other qdiscs.

ALGORITHM

       The  algorithm  is  very  similar to that of the classful tc-prio(8) qdisc.  pfifo_fast is like three tc-
       pfifo(8) queues side by side, where packets can be enqueued in any of the three bands based on their Type
       of Service bits or assigned priority.

       Not  all  three bands are dequeued simultaneously - as long as lower bands have traffic, higher bands are
       never dequeued. This can be used to prioritize interactive traffic or penalize 'lowest cost' traffic.

       Each band can be txqueuelen packets long, as configured with ip(8).  Additional packets coming in are not
       enqueued but are instead dropped.

       See tc-prio(8) for complete details on how TOS bits are translated into bands.

PARAMETERS

       txqueuelen
              The length of the three bands depends on the interface txqueuelen, as specified with ip(8).

BUGS

       Does  not  maintain  statistics  and does not show up in tc qdisc ls. This is because it is the automatic
       default in the absence of a configured qdisc.

SEE ALSO

       tc(8)

AUTHORS

       Alexey N. Kuznetsov, <kuznet@ms2.inr.ac.ru>

       This manpage maintained by bert hubert <ahu@ds9a.nl>