tcp.7p (2010 09)

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TCP(7P) TCP(7P)
This option is the same as TCP_ABORT_THRESHOLD
, except that this value is used
during connection establishment. When it must retransmit the SYN packet because
a timer has expired, TCP first compares the total time it has waited against the two
thresholds. If it has waited longer than the second threshold, TCP terminates the
connection. The default value for this option is the current value of the ndd tunable
tcp_ip_abort_cinterval
. See ndd(1M) online help for details on the
tcp_ip_abort_cinterval
default value.
TCP_KEEPCNT
(non-boolean option) When the SO_KEEPALIVE option is enabled, TCP probes a
connection that has been idle for some amount of time. If the remote system does
not respond to a keepalive probe, TCP retransmits the probe for a certain number of
times before a connection is considered to be broken. Use the
TCP_KEEPCNT
option with the TCP_KEEPINTVL
option to affect this value for a given socket. If
the remote system does not respond to a keepalive probe, TCP retransmits the
probe after some amount of time. The time interval between each keepalive probe
is decided by the TCP’s normal retransmission algorithm. Users do not have direct
control of the algorithm. For a given socket, the expression
(
TCP_KEEPINTVL
*TCP_KEEPCNT) determines when the retransmission attempts
will time out and the connection is broken. If both
TCP_KEEPINTVL and
TCP_KEEPCNT are not specified or if either one of them is not specified, then the
retransmission algorithm will run up to
tcp_ip_abort_interval. This option
takes an
int value, with a range of 1 to 32767.
TCP_KEEPIDLE
(non-boolean option) When the SO_KEEPALIVE option is enabled, TCP probes a
connection that has been idle for some amount of time. The default value for this
idle period is 2 hours. The TCP_KEEPIDLE option can be used to affect this value
for a given socket, and specifies the number of seconds of idle time between
keepalive probes. This option takes an int value, with a range of 1 to 32767.
TCP_KEEPINIT
(non-boolean option) If a TCP connection cannot be established within some
amount of time, TCP will time out the connect attempt. The default value for this
initial connection establishment timeout is 75 seconds. The
TCP_KEEPINIT option
can be used to affect this initial timeout period for a given socket, and specifies the
number of seconds to wait before the connect attempt is timed out. For passive con-
nections, the
TCP_KEEPINIT option value is inherited from the listening socket.
This option takes an int value, with a range of 1 to 32767.
TCP_KEEPINTVL
(non-boolean option) When the SO_KEEPALIVE option is enabled, TCP probes a
connection that has been idle for some amount of time. This option is used with the
TCP_KEEPCNT option. Refer to the description of TCP_KEEPCNT option above.
This option takes an int value, with a range of 1 to 32767.
TCP_TSOPTENA
(boolean option) When this option is enabled, the sender places a timestamp in each
data segment. The receiver, if configured to accept them, sends these timestamps
back in ACK segments. This provides the sender with a mechanism with which to
measure round-trip time. TCP provides a Boolean option, TCP_TSOPTENA (from
the <netinet/tcp.h> header file) to enable or disable this option. This option
takes an int value. When this option is enabled, the TCP_PAWS option is also
enabled.
TCP_PAWS (boolean option) When the PAWS (Protect Against Wrapped Sequence numbers)
option is enabled, the receiver rejects any old duplicate segments that are received.
This option is used on synchronized TCP connections only. TCP provides a Boolean
option, TCP_PAWS (from the <netinet/tcp.h> header file) to enable or disable
this option. This option takes an int value. This option automatically turns the
TCP_TSOPTENA option on.
TCP_SACKENA
(boolean option) When the Selective Acknowledgment (SACK) option is enabled, the
data receiver can inform the sender about all segments that have arrived success-
fully. In this way, the sender need retransmit only those segments that have
2 Hewlett-Packard Company − 2 − HP-UX 11i Version 3: September 2010