Originally posted by: bsobel
The people claiming that their is a TCP/IP connection limit in SP2 are spreading FUD (this isn't directed at you elkinm, I'll explain what MS did in a second). I've seen this 'limit' quoted on a zillion sites, and it simply not true.
What was added was a queue (not a limit) of the number of uncompleted TCP connection outstanding. The default queue size is 10. Which means you can attempt to establish 10 TCP connection at once and their is no change in the behaviour. If you try to establish 20 at once, the first 10 are put on the wire while the next 10 are queued and released as those first 10 either complete or fail (e.g. first connection is built, #11 is put on the wire, #4 fails, #12 is put on the wire, and so on).
In 'normal' usage, TCP connection establish quickly and you simply won't notice any difference. Where you will see a difference is if you try to create a large number of connections to sites which are not listening/responding to your requests (so in your examples "Multiple IE or other active browsers, multiple downloads, multiple email, telnet, ftp, ssh clients and others may run. Norton update, weatherbug, VPN, terminal services, and a telnet and web server on my PC, and possibly multiple multisource download clients and programs, by own or something like steam or fileplanet." there are all services which will respond quickly and even if you tried really hard, I do not believe you would ever be able to determine if the queuing happened.)
So, why the change? Flash worms that utilize TCP connections typically sit and loop while connecting to a random IP (they then attempt to infect that machine and they go back to picking another random target). Some of these worms can literally eat up your entire connection while they sit and pump packets out, since many of the destinations are not going to be valid targets (since the selection was random) this queue will kick in and help throttle how quickly the worm can leave the box.
Even throttled the worm will still spread quickly, but more importantly (and the reason for this feature), your connection will not become so unusable that you will be unable to access updates/repair tools/patches/etc.
Bill