I am running client load testing software for my server from a Windows 7 Enterprise box. The client box is able to get up to 16346 TCP connections out, and then it starts giving the error “An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full” and doesn't make any more connections. As far as I understood, Windows 7 is only limited for TCP connections by the amount of memory you have, and the usual limit on ephemeral ports. The 16346 number sounds suspiciously close to 16635, suggesting some funny limit. Any ideas?
EDIT: I figured it out. The ephemeral ports needed adjusting. There were only 16384 available. Fixed as per the instructions here: http://www.speedguide.net/read_articles.php?id=2574