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tcp.7: Document /proc file tcp_frto_response (new in Linux 2.6.22)
Text taken from Documentation/networking/ip-sysctl.txt Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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@ -357,6 +357,39 @@ where packet loss is typically due to random radio interference
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rather than intermediate router congestion.
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See RFC 4138 for more details.
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.TP
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.IR tcp_frto_response " (integer; default: 0; since Linux 2.6.22)"
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When F-RTO has detected that a TCP retransmission timeout was spurious
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(i.e, the timeout would have been avoided had TCP set a
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longer retransmission timeout),
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TCP has several options concerning what to do next.
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Possible values are:
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.RS
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.IP 0 3
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Rate halving based; a smooth and conservative response,
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results in halved congestion window
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.RI ( cwnd )
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and slow-start threshold
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.RI ( ssthresh )
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after one RTT.
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.IP 1
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Very conservative response; not recommended because even
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though being valid, it interacts poorly with the rest of
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Linux TCP; halves
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.I cwnd
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and
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.I ssthresh
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immediately.
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.IP 2
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Aggressive response; undoes congestion-control measures
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that are now known to be unnecessary
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(ignoring the possibility of a lost retransmission that would require
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TCP to be more cautious);
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.I cwnd
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and
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.I ssthresh
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are restored to the values prior to timeout.
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.RE
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.TP
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.IR tcp_keepalive_intvl " (integer; default: 75; since Linux 2.4)"
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.\" Since 2.3.18
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The number of seconds between TCP keep-alive probes.
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