tc-pbfifo

PBFIFO(8)			    Linux			    PBFIFO(8)



NAME
       pfifo - Packet limited First In, First Out queue

       bfifo - Byte limited First In, First Out queue


SYNOPSIS
       tc qdisc ... add pfifo [ limit packets ]

       tc qdisc ... add bfifo [ limit bytes ]


DESCRIPTION
       The  pfifo  and bfifo qdiscs are unadorned First In, First Out queues.
       They are the simplest queues possible and therefore have no  overhead.
       pfifo constrains the queue size as measured in packets.	bfifo does so
       as measured in bytes.

       Like all non-default qdiscs, they maintain statistics. This might be a
       reason to prefer pfifo or bfifo over the default.


ALGORITHM
       A  list	of  packets  is maintained, when a packet is enqueued it gets
       inserted at the tail of a list. When a packet needs to be sent out  to
       the network, it is taken from the head of the list.

       If  the	list  is too long, no further packets are allowed on. This is
       called ’tail drop’.


PARAMETERS
       limit  Maximum queue size. Specified in bytes for  bfifo,  in  packets
	      for  pfifo. For pfifo, defaults to the interface txqueuelen, as
	      specified with ifconfig(8) or ip(8).

	      For bfifo, it defaults to	 the  txqueuelen  multiplied  by  the
	      interface MTU.


OUTPUT
       The  output of tc -s qdisc ls contains the limit, either in packets or
       in bytes, and the number of bytes and packets actually sent. An unsent
       and  dropped  packet only appears between braces and is not counted as
       ’Sent’.

       In this example, the queue length is 100	 packets,  45894  bytes	 were
       sent  over  681	packets.   No  packets were dropped, and as the pfifo
       queue does not slow down packets, there were also no overlimits:

       # tc -s qdisc ls dev eth0
       qdisc pfifo 8001: dev eth0 limit 100p
	Sent 45894 bytes 681 pkts (dropped 0, overlimits 0)

       If a backlog occurs, this is displayed as well.

SEE ALSO
       tc(8)


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

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





iproute2		       10 January 2002			    PBFIFO(8)