47759e6333
1) dupseg_fix_=true from NS: do not count a segment with completely duplicate data as a duplicate ack. This can occur due to duplicate packets in the network, or due to fast retransmit from the other side. 2) dupack_reset_=false from NS: do not reset the duplicate ack counter or exit fast recovery if we happen to get data or a window update along with a duplicate ack. 3) In the "very old ack" case that itojun added, send an ACK before dropping the segment, to try to update the other side's send sequence number. 4) Check the ssthresh crossover point with >= rather than >. Otherwise we start to do "exponential" growth immediately following recovery, where we should be doing "linear". This is what NS does.