Send Keep Alive Packets
In some cases, Host Integrator may become aware of Telnet communication problems only after a significant delay or when it attempts to send data to the host. This can cause problems if you enter a large amount of data on one screen or if you keep your connection open during periods of inactivity.
To become aware of connection problems as they occur, you can configure your
model to send Keep Alive packets. Four methods are available:
- When Send Keep Alive Packets is set to None, Host Integrator
does not send any keep alive packets to the host. This is the default value.
- Send NOP Packets
- When Send Keep Alive Packets is set to Send NOP Packets, Host
Integrator periodically sends a No Operation (NOP) command to the host. The
gateway and host are not required to respond to these commands, but the TCP/IP
stack can detect if there was a problem delivering the packet.
- When Send Keep Alive Packets is set to System, the TCP/IP
stack keeps track of the host connection. This method requires less system
resources than Send Timing Mark Packets or Send NOP Packets, but most TCP/IP
stacks send Keep Alive packets infrequently.
- Send Timing Mark Packets
- When Send Keep Alive Packets is set to Send Timing Mark Packets,
Host Integrator periodically sends a Timing Mark Command to the host to determine
if the connection is still active. The gateway or host should respond to these
commands. If a response is not received or there is an error sending the packet,
it will shut down the connection. To view the average amount of time has waited
for a response to a Timing Mark Command in the Design Tool, open the View
Settings dialog box and select the Telnet Average Keep Alive Roundtrip setting.