- Airlink+ Network Router User Manual

Host RJ-11 IP Gateway User Guide, version 26
Configuration Settings and Commands
In one type of configuration, the Host RJ-11 IP Gateway has been designed to work in conjunction
with an AirLink Raven-E. The IP address for the Host RJ-11 IP Gateway and the IP address for the
Raven-E need to be on the same network. If you need to set a specific IP address for the Raven-E
and the Host RJ-11 IP Gateway, you will need to use Private Mode for the Raven-E. Setting Private
Mode is covered in the Raven-E User Guide.
FIGURE 9. Host RJ-11 IP Gateway: Network Interface Settings
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 device server’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 con
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nection 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 time-out larger to
reduce network traffic.