rdisp/keepalive_timeout is a SAP Parameter attribute which is used to control Timeout for connection to SAPGUI information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
The dispatcher periodically checks GUI connections if no data has been
transferred. It then sends a message to the GUI and waits rdi
sp/keepalive_timeout seconds for an answer. If it does not receive an
answer in this time period, it assumes there is a network error and
terminates the connection. The frequency with which the connections are
to be checked is defined by the parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.