know better when to cache values in the route, rather than relying on a
heuristic involving sequence numbers that broke when tcp_sendspace
was increased to 16k.
its connection parameters, we want to keep statistics on how often this
actually happens to see whether there is any work that needs to be done in
TCP itself.
Suggested by: John Wroclawski <jtw@lcs.mit.edu>
Bob Braden <braden@isi.edu>.
NB: This has not had David's TCP ACK hack re-integrated. It is not clear
what the correct solution to this problem is, if any. If a better solution
doesn't pop up in response to this message, I'll put David's code back in
(or he's welcome to do so himself).
