Manual: tc-pfifo_fast

PFIFO_FAST(8)						    Linux					       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 at‐
       tached, it preempts the default pfifo_fast, which automatically returns to function when an  existing  qdisc  is	 de‐
       tached.

       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	 de‐
       queued. 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, 

       This manpage maintained by bert hubert 

iproute2					       10 January 2002					       PFIFO_FAST(8)