TCP Timeout Parameters for Solaris

TCP Parameters With Additional Cautions

Changing the following parameters is not recommended unless there are extenuating circumstances that are described with each parameter.

tcp_ip_abort_interval
Description
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.
Default
8 minutes
Range
500 millisecond to 1193 hours
Dynamic?
Yes
When to Change
Do not change this value. See tcp_rexmit_interval_max for exceptions.
Commitment Level
Unstable

tcp_rexmit_interval_initial
Description
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.
Default
3 seconds
Range
1 millisecond to 20 seconds
Dynamic?
Yes
When to Change
Do not change this value. Lowering the value can result in unnecessary retransmissions.
Commitment Level
Unstable

tcp_rexmit_interval_max
Description
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.
Default
60 seconds
Range
1 millisecond to 2 hours
Dynamic?
Yes
When to Change
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.
Commitment Level
Unstable


Example Setting:
/usr/sbin/ndd -set /dev/tcp tcp_ip_abort_interval 480000