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Linux 2.6 - man page for tc-bfifo (linux section 8)

PBFIFO(8)				      Linux					PBFIFO(8)

       pfifo - Packet limited First In, First Out queue

       bfifo - Byte limited First In, First Out queue

       tc qdisc ... add pfifo [ limit packets ]

       tc qdisc ... add bfifo [ limit bytes ]

       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  mea-
       sured 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.

       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'.

       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.

       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.


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

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

iproute2				 10 January 2002				PBFIFO(8)

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