Re: Using tn5250

[Holger Schurig <holgerschurig@xxxxxxxxx>]

> When you press ENTER (or any function key), the data entered is
> sent to your server and then a response (display refresh) is
> sent back to the workstation from your server. If a packet is
> lost in either direction the communication is "out of sync" -
> the display waits for an answer from the server which is not
> coming because: 

That is only half-ways true. Telnet doesn't use UDP, it uses TCP. 
And here the TCP/IP-Stacks (on your box and on the AS/400) will 
automatically retry the "lost" packet when no explicit or 
implicit ACK comes back. On Linux, this retry-behavior is 
tuneable, e.g. via /proc/sys/net/ipv4. 


> answer was totally / partially lost in the network.

A totally lost answer will terminate the TCP/IP connection.

However, note that with the default settings this can take a 
looooong time (more than half-n-hour!), because of the 
exponential backup.


Just run wireshark / tshark on your client, press the ENTER key 
and observe the behavior. Now dismount the antenna on your AP 
and again press the ENTER key. And see what happens now :-)  Be 
sure to keep tshark running until the connection will be 
terminated. 



Best regards,
Holger