Gerrit Renker 113ced1f52 dccp ccid-2: Perform congestion-window validation ... CCID-2's cwnd increases like TCP during slow-start, which has implications for * the local Sequence Window value (should be > cwnd), * the Ack Ratio value. Hence an exponential growth, if it does not reflect the actual network conditions, can quickly lead to instability. This patch adds congestion-window validation (RFC2861) to CCID-2: * cwnd is constrained if the sender is application limited; * cwnd is reduced after a long idle period, as suggested in the '90 paper by Van Jacobson, in RFC 2581 (sec. 4.1); * cwnd is never reduced below the RFC 3390 initial window. As marked in the comments, the code is actually almost a direct copy of the TCP congestion-window-validation algorithms. By continuing this work, it may in future be possible to use the TCP code (not possible at the moment). The mechanism can be turned off using a module parameter. Sampling of the currently-used window (moving-maximum) is however done constantly; this is used to determine the expected window, which can be exploited to regulate DCCP's Sequence Window value. This patch also sets slow-start-after-idle (RFC 4341, 5.1), i.e. it behaves like TCP when net.ipv4.tcp_slow_start_after_idle = 1. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>		2011-07-04 12:37:49 -06:00
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lib
ccid2.c
ccid2.h
ccid3.c
ccid3.h
Kconfig