Sierra Wireless RJ-11 - Manual (Page 36)

Rev 3.0 B 2/15/08 31
Figure 2-8: 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 connec‐
tions. 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 connec‐
tions, 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.