On Sun, 3 Sep 2006 06:39:48 -0500, David Lesser <[EMAIL PROTECTED]> wrote:
>My Telnet parms are : >TIMERS > INACTIVE 28800 > KEEPINACTIVE 0 (OFF) > PRTINACTIVE 0 (OFF) > SCANINTERVAL 600 > TIMEMARK 999999 > SSLTIMEOUT 5 > >With these parms, if a Telnet device (Terminal/printer) is inactive for >3 hours or more, it does not respond. >The displays on the MF and PC show that device is active and there are >no messages of disconnect etc. > >I changed TIMEMARK to 900 and everything works fine. > >Any ideas ? Hi David, Could this be a firewall issue? TIMEMARK/SCANINTERVAL is the TN3270 equivalent to Telnet's AYT (Are You There?). As TCP allows connections to be idle forever, the TN3270 Server uses TIMEMARK/SCANINTERVAL to terminate these idle connections. If the TIMEMARK is overly long a connection can stay idle for several hours or days before it's considered for termination. The problem is that firewalls don't like idle TCP connections and will probably trash connections after 60 minutes. Unfortunately, the firewalls don't send RST packets to the TN3270 Server or Client when they do this, so as far as they are concerned the TCP connection is still established. The TN3270 Client is the first to discover the problem as they'll get a connection timeout if any 3270 command is sent to the host. On reconnection, they'll use a different local port which will be seen as a new connection with a D TCPIP,,TELNET command. The TN3270 Server will only become aware that the original connection has gone at the SCANINTERVAL following the TIMEMARK expiry - in your original case 11.5 days or so later. If you have a large network of TN3270 users, it's advisable not to set too low a value as you'll get TIMEMARK storms during periods of normal inactivity - like lunchtimes. IBM changed the defaults to 1800/10800 from 600/900 in OS/390 2.10 to alleviate this but neglected to mention that firewalls can have a major impact if their TCP disconnection timer is less than 2*SCANINTERVAL + TIMEMARK. Cheers Lee > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, >send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO >Search the archives at http://bama.ua.edu/archives/ibm-main.html >========================================================================= ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
