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-.TH RED 8 "13 December 2001" "iproute2" "Linux"
-.SH NAME
-red \- Random Early Detection
-.SH SYNOPSIS
-.B tc qdisc ... red
-.B limit
-bytes
-.B min
-bytes
-.B max
-bytes
-.B avpkt
-bytes
-.B burst
-packets
-.B [ ecn ] [ bandwidth
-rate
-.B ] probability
-chance
-
-.SH DESCRIPTION
-Random Early Detection is a classless qdisc which manages its queue size
-smartly. Regular queues simply drop packets from the tail when they are
-full, which may not be the optimal behaviour. RED also performs tail drop,
-but does so in a more gradual way.
-
-Once the queue hits a certain average length, packets enqueued have a
-configurable chance of being marked (which may mean dropped). This chance
-increases linearly up to a point called the
-.B max
-average queue length, although the queue might get bigger.
-
-This has a host of benefits over simple taildrop, while not being processor
-intensive. It prevents synchronous retransmits after a burst in traffic,
-which cause further retransmits, etc.
-
-The goal is the have a small queue size, which is good for interactivity
-while not disturbing TCP/IP traffic with too many sudden drops after a burst
-of traffic.
-
-Depending on if ECN is configured, marking either means dropping or
-purely marking a packet as overlimit.
-.SH ALGORITHM
-The average queue size is used for determining the marking
-probability. This is calculated using an Exponential Weighted Moving
-Average, which can be more or less sensitive to bursts.
-
-When the average queue size is below
-.B min
-bytes, no packet will ever be marked. When it exceeds
-.B min,
-the probability of doing so climbs linearly up
-to
-.B probability,
-until the average queue size hits
-.B max
-bytes. Because
-.B probability
-is normally not set to 100%, the queue size might
-conceivably rise above
-.B max
-bytes, so the
-.B limit
-parameter is provided to set a hard maximum for the size of the queue.
-
-.SH PARAMETERS
-.TP
-min
-Average queue size at which marking becomes a possibility.
-.TP
-max
-At this average queue size, the marking probability is maximal. Should be at
-least twice
-.B min
-to prevent synchronous retransmits, higher for low
-.B min.
-.TP
-probability
-Maximum probability for marking, specified as a floating point
-number from 0.0 to 1.0. Suggested values are 0.01 or 0.02 (1 or 2%,
-respectively).
-.TP
-limit
-Hard limit on the real (not average) queue size in bytes. Further packets
-are dropped. Should be set higher than max+burst. It is advised to set this
-a few times higher than
-.B max.
-.TP
-burst
-Used for determining how fast the average queue size is influenced by the
-real queue size. Larger values make the calculation more sluggish, allowing
-longer bursts of traffic before marking starts. Real life experiments
-support the following guideline: (min+min+max)/(3*avpkt).
-.TP
-avpkt
-Specified in bytes. Used with burst to determine the time constant for
-average queue size calculations. 1000 is a good value.
-.TP
-bandwidth
-This rate is used for calculating the average queue size after some
-idle time. Should be set to the bandwidth of your interface. Does not mean
-that RED will shape for you! Optional.
-.TP
-ecn
-As mentioned before, RED can either 'mark' or 'drop'. Explicit Congestion
-Notification allows RED to notify remote hosts that their rate exceeds the
-amount of bandwidth available. Non-ECN capable hosts can only be notified by
-dropping a packet. If this parameter is specified, packets which indicate
-that their hosts honor ECN will only be marked and not dropped, unless the
-queue size hits
-.B limit
-bytes. Needs a tc binary with RED support compiled in. Recommended.
-
-.SH SEE ALSO
-.BR tc (8)
-
-.SH SOURCES
-.TP
-o
-Floyd, S., and Jacobson, V., Random Early Detection gateways for
-Congestion Avoidance. http://www.aciri.org/floyd/papers/red/red.html
-.TP
-o
-Some changes to the algorithm by Alexey N. Kuznetsov.
-
-.SH AUTHORS
-Alexey N. Kuznetsov, <kuznet@ms2.inr.ac.ru>, Alexey Makarenko
-<makar@phoenix.kharkov.ua>, J Hadi Salim <hadi@nortelnetworks.com>.
-This manpage maintained by bert hubert <ahu@ds9a.nl>
-
-
git://git.onelab.eu / iproute2.git / blobdiff