kind(1 字节) length(1 字节) info(8 个字节)
SRTT = (α * SRTT) ((1 - α) * RTT)
RTO = min(ubound, max(lbound, β * SRTT))
SRTT = (1 - α) * SRTT α * RTT
RTTVAR = (1 - β) * RTTVAR β * (|RTT - SRTT|)
RTO = µ * SRTT ∂ * RTTVAR
发送窗口大小 = min(rwnd, cwnd)
sudo sysctl -a | grep keepalive // 每隔 7200 s 检测一次net.ipv4.tcp_keepalive_time = 7200// 一次最多重传 9 个包net.ipv4.tcp_keepalive_probes = 9// 每个包的间隔重传间隔 75 snet.ipv4.tcp_keepalive_intvl = 75