tcp-ip@ucbvax.ARPA (07/27/85)
From: don.provan@CMU-CS-A.ARPA The time I need to probe a connection most is not one of the three mentioned. That's when there was a user, but there isn't any more. For example, an inbound Telnet connection will sit around tieing up resources forever if the remote host goes down while nothing's happening on the connection. I implemented it as a general solution, since I can't imagine a connection where that can't happen. After all, the connection is a TCP resource. There's no way for me to determine whether the TCP connection or the network links in use for it are more valuable. In fact, I only implemented probing because TCP keep running out of connection blocks. For the curious, I probe with spontaneous ACKs.