Connection persistence
Several timers are available in Telnet to control how long connections
stay up. The list includes:
- INACTIVE - How long a terminal connection can be idle with no SNA data traffic before the connection is dropped.
- PRTINACTIVE - How long a printer connection can be idle with no SNA data traffic before the connection is dropped.
- PROFILEINACTIVE - How long a Telnet connection can be active with no active SNA session, while it is associated with a Telnet profile that is not the current profile.
- KEEPINACTIVE - How long a KEEPOPEN connection can be idle with no SNA session before the connection is dropped. When a KEEPOPEN connection is in session with a SNA application the INACTIVE timer is used instead of the KEEPINACTIVE timer.
- SCANINTERVAL - How often Telnet runs the list of connections looking for potentially lost connections. Because of the methodology, it also determines how long Telnet will wait for a TIMEMARK response before assuming the connection is lost.
- TIMEMARK - How long a connection is active without receiving any data before Telnet sends a TIMEMARK command which acts as an "are you there".
- SSLTIMEOUT - How long Telnet will wait for an SSL handshake initiation from the client before the request is dropped.
To facilitate these timers, Telnet records the time at which data is received from the client, received from VTAM®, or sent to VTAM. Data received from the client is used by SCANINTERVAL/TIMEMARK to measure idle time on the connection. Data received from or sent to VTAM is used by the INACTIVE family of timers to measure idle time without SNA data traffic.
SSLTIMEOUT is different than the other timers. Telnet does not run this timer. The time value is passed to the SSL handshake process. If SSL does not get a response from the client within SSLTIMEOUT period of time, the handshake request fails. Telnet will then proceed to the next available connection negotiation method or drop the connection.