5.16 CONKPALV (Console and telnet clients keep-alive option)

5.16.1 Function

The CONKPALV parameter specifies the tn3270 console and telnet client keep-alive option values that
control automatic detection of disconnected tn3270 / telnet client sessions.

This is a built-in feature of TCP/IP that allows detection of unresponsive TCP/IP connections and not idle
clients; the connection will not be terminated after the specified idle time. The 3270 sessions can remain
idle for a long time without any data being transmitted. The TCP/IP Keep-Alive feature only detects un-
responsive TCP/IP stacks. Thus, even if the 3270 client is completely idle, the systems TCP/IP stack itself
still should respond to the keep-alive probes sent from the Hercules end of the link. If it does not however,
then the TCP/IP connection is obviously down and the 3270 sessions at the Hercules end of the link are
terminated as a consequence.

Some older platforms may ignore all of the specified values and use platform specific values instead.

5.16.2 Syntax

Descriptive

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Diagram

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5.16.3 Parameter

idle

The idle value specifies the number of seconds of inactivity until the first keep-alive
probe is sent. The default for the idle value is 3 seconds.

intv

The intv value specifies the interval in seconds between the probes if no acknow-
ledgement is received from the previous probe. The default for intv is 1 second.

count

The count value specifies the number of unacknowledged keep-alive packets sent
before the connection is considered to have failed. The default value is 10.

Note: On Windows platforms the count value is ignored and cannot be changed
from its default value of 10.

5.16.4 Examples

Example 1:

Set the tn3270 console and telnet clients keep-alive option settings to the following values: 5 seconds of
inactivity until the first keep-alive probe is sent, 3 seconds for the interval between the probes and to 15
unacknowledged keep-alive packets sent before the connection is considered to have failed.

CONKPALV (5,3,15)

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