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Message-ID: <520AC82A.5040303@gmail.com>
Date: Tue, 13 Aug 2013 19:58:34 -0400
From: Dong Fang <yp.fangdong@...il.com>
To: netdev@...r.kernel.org, Dong Fang <yp.fangdong@...il.com>
Subject: the congestion window rfc2001
-------- Original Message --------
Subject: the congestion window rfc2001
Date: Tue, 13 Aug 2013 19:35:09 -0400
From: Dong Fang <yp.fangdong@...il.com>
To: netdev@...r.kernel.org
hi, all
http://tools.ietf.org/html/rfc2001
1. When the third duplicate ACK in a row is received, set ssthresh
to one-half the current congestion window, cwnd, but no less
than two segments. Retransmit the missing segment. Set cwnd =
ssthresh + 3 times the segment size. This inflates the
-- what is the meaning of '3'
congestion window by the number of segments that have left the
network and which the other end has cached (3).
2. Each time another duplicate ACK arrives, increment cwnd by the
segment size. This inflates the congestion window for the
additional segment that has left the network.
-- why do this
Transmit a packet, if allowed by the new value of cwnd.
3. When the next ACK arrives that acknowledges new data, set cwnd
to ssthresh (the value set in step 1). This ACK should be the
acknowledgment of the retransmission from step 1, one round-trip
time after the retransmission. Additionally, this ACK should
acknowledge all the intermediate segments sent between the lost
packet and the receipt of the first duplicate ACK. This step is
congestion avoidance, since TCP is down to one-half the rate it
was at when the packet was lost.
--
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