Hardware manual

80-001113 SysLINK Administrator’s Guide Page 33
TCP Keep-Alive
TCP keep-alive is a standard feature of TCP/IP that can be configured to automatically
monitor the state of TCP connections. If one end of an idle TCP connection is severed (like
by a network or power failure), it is possible for the other end to remain open indefinitely. If
a network host fails while it has an open TCP connection to one of the gateway’s serial ports,
that serial port might remain unavailable until it is manually reset.
The optional TCP keep-alive feature sends special “keep-alive” packets to the remote TCP
host in order to detect the situation where the remote host fails. If a failure is detected, the
TCP connection is reset to allow other hosts to access the serial port.
To enable TCP keep-alives on serial-related network connections, enter the total time (in
seconds) that you will allow TCP connections to remain idle before resetting them. The first
keep-alive packet will be sent after the connection has been idle for half of this total time.
After that, four more TCP keep-alive packets will be sent at regular intervals until a TCP
response is received from the remote host. If no response is received before the total keep-
alive time runs out, the TCP connection will be reset.
CAUTION: Enabling TCP keep-alives will increase the amount of network traffic on
your network. Unless you have a specific need for this feature, it is best to leave it
disabled. If you do enable it, it is best to make the keep-alive timeout larger to
reduce network traffic.
HTTP Server Configuration
You may specify the HTTP and HTTPS ports that the gateway will listen on for
configuration settings.