User`s manual

Installing under OS/400
AX3000 - User's Manual 139
6.5.2 - Reconnection Problem
If an AX3000 5250 session is set with a specific DEVNAME, problems can
occur if it is not cleanly shutdown before being switched off.
If the terminal is powered off without signing off first the As/400 will be unaware
the connection is broken and will still consider the connection to be valid and in
use. If the terminal then tries to sign on with the same devname the As/400 will
refuse connection.
This problem can be solved by tuning 'keepalive' function of the OS/400 Telnet
Server. The keepalive function allows sessions to time out and die after a
certain time. Keepalive probes are automatically sent by the OS/400 host when
a connection has been idle for a specified time. If the TCP/IP peripheral does
not respond, the connection is dropped. The socket is released and applications
associated with the connection are killed.
Note: to check the status of sockets, use the OS/400 netstat command.
By default, the keepalive time out value is very high (sometimes infinite). So this
value must be decreased to allow the OS/400 to check regularly the TCP/IP
connection status. Invoke the following command to change this value (xxx are
seconds):
===> CHGTELNA TIMMRKTIMO(xxx)
This modification will take effect after restarting the telnet server:
===> ENDTCPSVR SERVER(*TELNET)
===> STRTCPSVR SERVER(*TELNET)
IMPORTANT: using a small keepalive value can prevent routers from dropping
the ISDN line and cause high connection bills.