This Integer32 value sets the number of seconds of inactivity on a TCP session before a TCP keep-alive packet is sent to check whether the peer is still reachable. It matters operationally because a shorter interval detects a dropped remote endpoint (e.g. a crashed management session) faster, at the cost of extra probe traffic. For example, an admin might set usrTcpKeepaliveInterval to 300 so an idle Telnet session is probed every 5 minutes of silence.