Changing the following parameters is not recommended unless there are extenuating circumstances that are described with each parameter.
The default total retransmission timeout value for a TCP connection in milliseconds. For a given TCP connection, if TCP has been retransmitting for tcp_ip_abort_interval period of time and it has not received any acknowledgment from the other endpoint during this period, TCP closes this connection.
For TCP retransmission timeout (RTO) calculation, refer to RFC 1122, 4.2.3. See also tcp_rexmit_interval_max.
8 minutes
500 millisecond to 1193 hours
Yes
Do not change this value. See tcp_rexmit_interval_max for exceptions.
Unstable
The default initial retransmission timeout (RTO) value for a TCP connection in milliseconds. Refer to the following discussion of per route metrics for setting a different value on a per-route basis.
3 seconds
1 millisecond to 20 seconds
Yes
Do not change this value. Lowering the value can result in unnecessary retransmissions.
Unstable
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.
60 seconds
1 millisecond to 20 seconds
Yes
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.
Unstable
The default minimum retransmission time-out (RTO) value in milliseconds. The calculated RTO for all TCP connections cannot be lower than this value. See also tcp_rexmit_interval_max.
400 milliseconds
1 millisecond to 20 seconds
Yes
Do not change the value in a normal network environment.
TCP's RTO calculation should be able to cope with most RTT fluctuations. If in some very special circumstances such that the round trip time (RTT) for a connection is in the order of 10 seconds, change to a higher value. If you change this value, you should change the tcp_rexmit_interval_max parameter to match it. You should change the value of tcp_rexmit_interval_max to at least eight times the value of tcp_rexmit_interval_min.
Unstable
A constant added to the calculated retransmission time-out value (RTO) in milliseconds.
0 milliseconds
0 to 2 hours
Yes
Do not change the value.
When the RTO calculation fails to obtain a good value for a connection in some circumstances, you can change this value to avoid unnecessary retransmissions.
Unstable
If this parameter is set to 1, and the window scale option is enabled for a connection, TCP also enables the timestamp option for that connection.
1 (enabled)
0 (disabled), 1 (enabled)
Yes
Do not change this value. In general, when TCP is used in high-speed network, protection against sequence number wraparound is essential, thus you need the timestamp option.
Unstable
Controls the default minimum receive window size. The minimum is tcp_recv_hiwat_minmss times the size of maximum segment size (MSS) of a connection.
4
1 to 65,536
Yes
Do not change the value. If changing it is necessary, do not change the value lower than 4.
Unstable
If set to 1, protocol control blocks of TCP connections in TIME-WAIT state are compressed to reduce memory usage. If set to 0, no compression is done. See tcp_time_wait_interval also.
1 (enabled)
0 (disabled), 1 (enabled)
Yes
Do not turn off the compression mechanism.
Unstable