PFIFO_FAST(8)           (10 January 2002)           PFIFO_FAST(8)

     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 penal-
          ize 'lowest cost' traffic.

          Each band can be txqueuelen packets long, as configured with
          ifconfig(8) or 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 ifconfig(8) or 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)

     Page 1                      iproute2            (printed 5/24/22)

     PFIFO_FAST(8)           (10 January 2002)           PFIFO_FAST(8)

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

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

     Page 2                      iproute2            (printed 5/24/22)