The default maximum retransmission timeout value (RTO) in milliseconds. The calculated RTO for all TCP connections cannot exceed this value. See also tcp_ip_abort_interval.
1 millisecond to 20 seconds
Do not change the value in a normal network environment.
If in some special circumstances, the round trip time (RTT) for a connection is in the order of 10 seconds, you can change the value to a higher value. If you change this value, you should also change the tcp_ip_abort_interval parameter to match it. Change the value of tcp_ip_abort_interval to at least four times the value of tcp_rexmit_interval_max.