tcp_rexmit_interval_min
| Description | 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.
| | Default | 400 milliseconds
| | Range | 1 millisecond to 20 seconds
| | Dynamic? | Yes
| | When to Change | 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.
| | Commitment Level | Unstable
|
tcp_rexmit_interval_extra
| Description | A constant added to
the calculated retransmission time-out value (RTO) in milliseconds.
| | Default | 0 milliseconds
| | Range | 0 to 2 hours
| | Dynamic? | Yes
| | When to Change | 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.
| | Commitment Level | Unstable
|
tcp_tstamp_if_wscale
| Description | 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.
| | Default | 1 (enabled)
| | Range | 0 (disabled), 1 (enabled)
| | Dynamic? | Yes
| | When to Change | 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.
| | Commitment Level | Unstable
|
tcp_recv_hiwat_minmss
| Description | 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.
| | Default | 4
| | Range | 1 to 65,536
| | Dynamic? | Yes
| | When to Change | Do not change the
value. If changing it is necessary, do not change the value lower than 4.
| | Commitment Level | Unstable
|
tcp_compression_enabled
| Description | 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.
| | Default | 1 (enabled)
| | Range | 0 (disabled), 1 (enabled)
| | Dynamic? | Yes
| | When to Change | Do not turn off the
compression mechanism.
| | Commitment Level | Unstable
|
UDP Tunable Parameters
This section describes some of the UDP tunable parameters.
udp_xmit_hiwat
| Description | The default maximum
UDP socket datagram size in bytes. For more information, see udp_max_buf.
| | Default | 8192 bytes
| | Range | 4096 to 65,536
| | Dynamic? | Yes
| | When to Change | Note that an application
can use setsockopt(3XNET) SO_SNDBUF to change the size for an individual socket. In general,
you do not need to change the default value.
| | Commitment Level | Unstable
|
udp_recv_hiwat
| Description | The default maximum
UDP socket receive buffer size in bytes. For more information, see udp_max_buf.
| | Default | 8192 bytes
| | Range | 4096 to 65,536
| | Dynamic? | Yes
| | When to Change | Note that an application
can use setsockopt(3XNET) SO_RCVBUF to change the size for an individual socket. In general,
you do not need to change the default value.
| | Commitment Level | Unstable
|
UDP Parameters with Additional Cautions
Changing the following parameters is not recommended unless there are
extenuating circumstances that are described with each parameter.
|
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