rdisp/ms_keepalive_timeout is a SAP Parameter attribute which is used to control Timeout for connection to Message Server 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 the message server connections if no
data has been transferred. It then sends a message to the GUI and waits
rdisp/ms_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
reduces the connection.
The frequency for how often the connections are to be checked is defined
by the parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.